@phdthesis{Zink2023,
  author    = {Zink, Christoph},
  title     = {Biochemische und strukturbiologische Charakterisierung der Inhibition der Pyridoxal 5´-Phosphat Phosphatase durch 7,8-Dihydroxyflavon},
  doi       = {10.25972/OPUS-25151},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-251511},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {Die Pyridoxal-5'-Phosphat Phosphatase (PDXP), auch bekannt als Chronophin (CIN), ist eine HAD-Phosphatase, die beim Menschen ubiquit{\"a}r exprimiert wird und eine entscheidende Rolle im zellul{\"a}ren Vitamin-B6-Metabolismus einnimmt. PDXP ist in der Lage Pyridoxal-5'-Phosphat (PLP), die co-enzymatisch aktive Form von Vitamin B6, zu dephosphorylieren. In-vivo Studien mit M{\"a}usen zeigten, dass die Abwesenheit von PDXP mit verbesserten kognitiven Leistungen und einem verringerten Wachstum von Hirntumoren assoziiert ist. Dies begr{\"u}ndet die gezielte Suche nach einem pharmakologischen Inhibitor f{\"u}r PDXP. Ein Hochdurchsatz-Screen legte nahe, dass 7,8-Dihydroxyflavon (7,8-DHF) hierf{\"u}r ein potenzieller Kandidat ist. Zahlreiche Studien beschreiben bereits vielf{\"a}ltige positive neurologische Effekte nach in-vivo Administration von 7,8-DHF, allerdings bleibt der genaue Wirkmechanismus umstritten und wird bis dato nicht mit PDXP in Zusammenhang gebracht. Ziel dieser Arbeit ist es, die Inhibition von PDXP durch 7,8-DHF n{\"a}her zu charakterisieren und damit einen Beitrag zur Beantwortung der Frage zu leisten, ob PDXP an den 7,8-DHF-induzierten Effekten beteiligt ist. Hierzu wurde der Effekt von 7,8-DHF auf die enzymatische Aktivit{\"a}t von rekombinant hergestelltem, gereinigtem PDXP in in-vitro Phosphatase-Assays charakterisiert. Um die Selektivit{\"a}t von 7,8-DHF gegen{\"u}ber PDXP zu untersuchen, wurden f{\"u}nf weitere HAD-Phosphatasen getestet. Unter den analysierten Phosphatasen zeigte einzig die dem PDXP nah verwandte Phosphoglykolat Phosphatase (PGP) eine geringer ausgepr{\"a}gte Sensitivit{\"a}t gegen 7,8-DHF. Ein Vergleich von 7,8-DHF mit sechs strukturell verwandten, hydroxylierten Flavonen zeigte, dass 7,8-DHF unter den getesteten Substanzen die h{\"o}chste Potenz und Effektivit{\"a}t aufwies. Außerdem wurde eine Co-Kristallisation von PDXP mit 7,8-DHF durchgef{\"u}hrt, deren Struktur bis zu einer Aufl{\"o}sung von 2,0 {\AA} verfeinert werden konnte. Die in der Kristallstruktur identifizierte Bindungsstelle von 7,8-DHF an PDXP wurde mittels verschiedener, neu generierter PDXP-Mutanten enzymkinetisch best{\"a}tigt. Zusammenfassend zeigen die hier beschriebenen Ergebnisse, dass 7,8-DHF ein direkter, selektiver und vorwiegend kompetitiver Inhibitor der PDXP-Aktivit{\"a}t ist, mit einer IC50 im submikromolaren Bereich. Die Ergebnisse dieser in-vitro Untersuchungen motivieren zu weiterer Forschung bez{\"u}glich der 7,8-DHF-vermittelten Inhibition der PDXP-Aktivit{\"a}t in Zellen, um die Frage beantworten zu k{\"o}nnen, ob PDXP auch in-vivo ein relevantes Target f{\"u}r 7,8-DHF darstellt.},
  subject      = {Pyridoxalphosphat},
  language  = {de}
}
@article{NwoghaAbtewRaveendranetal.2023,
  author    = {Nwogha, Jeremiah S. and Abtew, Wosene G. and Raveendran, Muthurajan and Oselebe, Happiness O. and Obidiegwu, Jude E. and Chilaka, Cynthia A. and Amirtham, Damodarasamy D.},
  title     = {Role of non-structural sugar metabolism in regulating tuber dormancy in white yam (Dioscorea rotundata)},
  series = {Agriculture},
  volume    = {13},
  journal   = {Agriculture},
  number    = {2},
  issn      = {2077-0472},
  doi       = {10.3390/agriculture13020343},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-304486},
  year      = {2023},
  abstract  = {Changes in sugar composition occur continuously in plant tissues at different developmental stages. Tuber dormancy induction, stability, and breaking are very critical developmental transitions in yam crop production. Prolonged tuber dormancy after physiological maturity has constituted a great challenge in yam genetic improvement and productivity. In the present study, biochemical profiling of non-structural sugar in yam tubers during dormancy was performed to determine the role of non-structural sugar in yam tuber dormancy regulation. Two genotypes of the white yam species, one local genotype (Obiaoturugo) and one improved genotype (TDr1100873), were used for this study. Tubers were sampled at 42, 56, 87, 101, 115, and 143 days after physiological maturity (DAPM). Obiaoturugo exhibited a short dormant phenotype and sprouted at 101-DAPM, whereas TDr1100873 exhibited a long dormant phenotype and sprouted at 143-DAPM. Significant metabolic changes were observed in non-structural sugar parameters, dry matter, and moisture content in Obiaoturugo from 56-DAPM, whereas in TDr1100873, significant metabolic changes were observed from 101-DAPM. It was observed that the onset of these metabolic changes occurred at a point when the tubers of both genotypes exhibited a dry matter content of 60\%, indicating that a dry matter content of 60\% might be a critical threshold for white yam tuber sprouting. Non-reducing sugars increased by 9-10-fold during sprouting in both genotypes, which indicates their key role in tuber dormancy regulation in white yam. This result implicates that some key sugar metabolites can be targeted for dormancy manipulation of the yam crop.},
  language  = {en}
}
@article{HadiBankogluStopper2023,
  author    = {Hadi, Naji Said Aboud and Bankoglu, Ezgi Eyluel and Stopper, Helga},
  title     = {Genotoxicity of pyrrolizidine alkaloids in metabolically inactive human cervical cancer HeLa cells co-cultured with human hepatoma HepG2 cells},
  series = {Archives of Toxicology},
  volume    = {97},
  journal   = {Archives of Toxicology},
  number    = {1},
  doi       = {10.1007/s00204-022-03394-z},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-324708},
  pages     = {295-306},
  year      = {2023},
  abstract  = {Pyrrolizidine alkaloids (PAs) are secondary plant metabolites, which can be found as contaminant in various foods and herbal products. Several PAs can cause hepatotoxicity and liver cancer via damaging hepatic sinusoidal endothelial cells (HSECs) after hepatic metabolization. HSECs themselves do not express the required metabolic enzymes for activation of PAs. Here we applied a co-culture model to mimic the in vivo hepatic environment and to study PA-induced effects on not metabolically active neighbour cells. In this co-culture model, bioactivation of PA was enabled by metabolically capable human hepatoma cells HepG2, which excrete the toxic and mutagenic pyrrole metabolites. The human cervical epithelial HeLa cells tagged with H2B-GFP were utilized as non-metabolically active neighbours because they can be identified easily based on their green fluorescence in the co-culture. The PAs europine, riddelliine and lasiocarpine induced micronuclei in HepG2 cells, and in HeLa H2B-GFP cells co-cultured with HepG2 cells, but not in HeLa H2B-GFP cells cultured alone. Metabolic inhibition of cytochrome P450 enzymes with ketoconazole abrogated micronucleus formation. The efflux transporter inhibitors verapamil and benzbromarone reduced micronucleus formation in the co-culture model. Furthermore, mitotic disturbances as an additional genotoxic mechanism of action were observed in HepG2 cells and in HeLa H2B-GFP cells co-cultured with HepG2 cells, but not in HeLa H2B-GFP cells cultured alone. Overall, we were able to show that PAs were activated by HepG2 cells and the metabolites induced genomic damage in co-cultured HeLa cells.},
  language  = {en}
}
@article{BittnerBoonDelbancoetal.2022,
  author    = {Bittner, Nataly and Boon, Andy and Delbanco, Evert H. and Walter, Christof and Mally, Angela},
  title     = {Assessment of aromatic amides in printed food contact materials: analysis of potential cleavage to primary aromatic amines during simulated passage through the gastrointestinal tract},
  series = {Archives of Toxicology},
  volume    = {96},
  journal   = {Archives of Toxicology},
  number    = {5},
  doi       = {10.1007/s00204-022-03254-w},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-324697},
  pages     = {1423-1435},
  year      = {2022},
  abstract  = {Recent analyses conducted by German official food control reported detection of the aromatic amides N-(2,4-dimethylphenyl)acetamide (NDPA), N-acetoacetyl-m-xylidine (NAAX) and 3-hydroxy-2-naphthanilide (Naphthol AS) in cold water extracts from certain food contact materials made from paper or cardboard, including paper straws, paper napkins, and cupcake liners. Because aromatic amides may be cleaved to potentially genotoxic primary amines upon oral intake, these findings raise concern that transfer of NDPA, NAAX and Naphthol AS from food contact materials into food may present a risk to human health. The aim of the present work was to assess the stability of NDPA, NAAX and Naphthol AS and potential cleavage to 2,4-dimethylaniline (2,4-DMA) and aniline during simulated passage through the gastrointestinal tract using static in vitro digestion models. Using the digestion model established by the National Institute for Public Health and the Environment (RIVM, Bilthoven, NL) and a protocol recommended by the European Food Safety Authority, potential hydrolysis of the aromatic amides to the respective aromatic amines was assessed by LC-MS/MS following incubation of the aromatic amides with digestive fluid simulants. Time-dependent hydrolysis of NDPA and NAAX resulting in formation of the primary aromatic amine 2,4-DMA was consistently observed in both models. The highest rate of cleavage of NDPA and NAAX was recorded following 4 h incubation with 0.07 M HCl as gastric-juice simulant, and amounted to 0.21\% and 0.053\%, respectively. Incubation of Naphthol AS with digestive fluid simulants did not give rise to an increase in the concentration of aniline above the background that resulted from the presence of aniline as an impurity of the test compound. Considering the lack of evidence for aniline formation from Naphthol AS and the extremely low rate of hydrolysis of the amide bonds of NDPA and NAAX during simulated passage through the gastrointestinal tract that gives rise to only very minor amounts of the potentially mutagenic and/or carcinogenic aromatic amine 2,4-DMA, risk assessment based on assumption of 100\% cleavage to the primary aromatic amines would appear to overestimate health risks related to the presence of aromatic amides in food contact materials.},
  language  = {en}
}
@article{NaseemOthmanFathyetal.2020,
  author    = {Naseem, Muhammad and Othman, Eman M. and Fathy, Moustafa and Iqbal, Jibran and Howari, Fares M. and AlRemeithi, Fatima A. and Kodandaraman, Geema and Stopper, Helga and Bencurova, Elena and Vlachakis, Dimitrios and Dandekar, Thomas},
  title     = {Integrated structural and functional analysis of the protective effects of kinetin against oxidative stress in mammalian cellular systems},
  series = {Scientific Reports},
  volume    = {10},
  journal   = {Scientific Reports},
  doi       = {10.1038/s41598-020-70253-1},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-231317},
  year      = {2020},
  abstract  = {Metabolism and signaling of cytokinins was first established in plants, followed by cytokinin discoveries in all kingdoms of life. However, understanding of their role in mammalian cells is still scarce. Kinetin is a cytokinin that mitigates the effects of oxidative stress in mammalian cells. The effective concentrations of exogenously applied kinetin in invoking various cellular responses are not well standardized. Likewise, the metabolism of kinetin and its cellular targets within the mammalian cells are still not well studied. Applying vitality tests as well as comet assays under normal and hyper-oxidative states, our analysis suggests that kinetin concentrations of 500 nM and above cause cytotoxicity as well as genotoxicity in various cell types. However, concentrations below 100 nM do not cause any toxicity, rather in this range kinetin counteracts oxidative burst and cytotoxicity. We focus here on these effects. To get insights into the cellular targets of kinetin mediating these pro-survival functions and protective effects we applied structural and computational approaches on two previously testified targets for these effects. Our analysis deciphers vital residues in adenine phosphoribosyltransferase (APRT) and adenosine receptor (A2A-R) that facilitate the binding of kinetin to these two important human cellular proteins. We finally discuss how the therapeutic potential of kinetin against oxidative stress helps in various pathophysiological conditions.},
  language  = {en}
}
@article{MaiellaroLohseKitteetal.2016,
  author    = {Maiellaro, Isabella and Lohse, Martin J. and Kitte, Robert J. and Calebiro, Davide},
  title     = {cAMP Signals in Drosophila Motor Neurons Are Confined to Single Synaptic Boutons},
  series = {Cell Reports},
  volume    = {17},
  journal   = {Cell Reports},
  number    = {5},
  doi       = {10.1016/j.celrep.2016.09.090},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-162324},
  pages     = {1238-1246},
  year      = {2016},
  abstract  = {The second messenger cyclic AMP (cAMP) plays an important role in synaptic plasticity. Although there is evidence for local control of synaptic transmission and plasticity, it is less clear whether a similar spatial confinement of cAMP signaling exists. Here, we suggest a possible biophysical basis for the site-specific regulation of synaptic plasticity by cAMP, a highly diffusible small molecule that transforms the physiology of synapses in a local and specific manner. By exploiting the octopaminergic system of Drosophila, which mediates structural synaptic plasticity via a cAMP-dependent pathway, we demonstrate the existence of local cAMP signaling compartments of micrometer dimensions within single motor neurons. In addition, we provide evidence that heterogeneous octopamine receptor localization, coupled with local differences in phosphodiesterase activity, underlies the observed differences in cAMP signaling in the axon, cell body, and boutons.},
  language  = {en}
}
@article{WeigandRonchiVanselowetal.2021,
  author    = {Weigand, Isabel and Ronchi, Cristina L. and Vanselow, Jens T. and Bathon, Kerstin and Lenz, Kerstin and Herterich, Sabine and Schlosser, Andreas and Kroiss, Matthias and Fassnacht, Martin and Calebiro, Davide and Sbiera, Silviu},
  title     = {PKA Cα subunit mutation triggers caspase-dependent RIIβ subunit degradation via Ser\(^{114}\) phosphorylation},
  series = {Science Advances},
  volume    = {7},
  journal   = {Science Advances},
  number    = {8},
  doi       = {10.1126/sciadv.abd4176},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-270445},
  year      = {2021},
  abstract  = {Mutations in the PRKACA gene are the most frequent cause of cortisol-producing adrenocortical adenomas leading to Cushing's syndrome. PRKACA encodes for the catalytic subunit α of protein kinase A (PKA). We already showed that PRKACA mutations lead to impairment of regulatory (R) subunit binding. Furthermore, PRKACA mutations are associated with reduced RIIβ protein levels; however, the mechanisms leading to reduced RIIβ levels are presently unknown. Here, we investigate the effects of the most frequent PRKACA mutation, L206R, on regulatory subunit stability. We find that Ser\(^{114}\) phosphorylation of RIIβ is required for its degradation, mediated by caspase 16. Last, we show that the resulting reduction in RIIβ protein levels leads to increased cortisol secretion in adrenocortical cells. These findings reveal the molecular mechanisms and pathophysiological relevance of the R subunit degradation caused by PRKACA mutations, adding another dimension to the deregulation of PKA signaling caused by PRKACA mutations in adrenal Cushing's syndrome.},
  language  = {en}
}
@article{AwadOthmanStopper2017,
  author    = {Awad, Eman and Othman, Eman M. and Stopper, Helga},
  title     = {Effects of resveratrol, lovastatin and the mTOR-inhibitor RAD-001 on insulin-induced genomic damage in vitro},
  series = {Molecules},
  volume    = {22},
  journal   = {Molecules},
  number    = {12},
  doi       = {10.3390/molecules22122207},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-159260},
  pages     = {2207},
  year      = {2017},
  abstract  = {Diabetes mellitus (DM) is one of the major current health problems due to lifestyle changes. Before diagnosis and in the early years of disease, insulin blood levels are elevated. However, insulin generates low levels of reactive oxygen species (ROS) which are integral to the regulation of a variety of intracellular signaling pathways, but excess levels of insulin may also lead to DNA oxidation and DNA damage. Three pharmaceutical compounds, resveratrol, lovastatin and the mTOR-inhibitor RAD-001, were investigated due to their known beneficial effects. They showed protective properties against genotoxic damage and significantly reduced ROS after in vitro treatment of cultured cells with insulin. Therefore, the selected pharmaceuticals may be attractive candidates to be considered for support of DM therapy.},
  language  = {en}
}
@article{LohseBockMaiellaroetal.2017,
  author    = {Lohse, Christian and Bock, Andreas and Maiellaro, Isabella and Hannawacker, Annette and Schad, Lothar R. and Lohse, Martin J. and Bauer, Wolfgang R.},
  title     = {Experimental and mathematical analysis of cAMP nanodomains},
  series = {PLoS ONE},
  volume    = {12},
  journal   = {PLoS ONE},
  number    = {4},
  doi       = {10.1371/journal.pone.0174856},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170972},
  pages     = {e0174856},
  year      = {2017},
  abstract  = {In their role as second messengers, cyclic nucleotides such as cAMP have a variety of intracellular effects. These complex tasks demand a highly organized orchestration of spatially and temporally confined cAMP action which should be best achieved by compartmentalization of the latter. A great body of evidence suggests that cAMP compartments may be established and maintained by cAMP degrading enzymes, e.g. phosphodiesterases (PDEs). However, the molecular and biophysical details of how PDEs can orchestrate cAMP gradients are entirely unclear. In this paper, using fusion proteins of cAMP FRET-sensors and PDEs in living cells, we provide direct experimental evidence that the cAMP concentration in the vicinity of an individual PDE molecule is below the detection limit of our FRET sensors (<100nM). This cAMP gradient persists in crude cytosol preparations. We developed mathematical models based on diffusion-reaction equations which describe the creation of nanocompartments around a single PDE molecule and more complex spatial PDE arrangements. The analytically solvable equations derived here explicitly determine how the capability of a single PDE, or PDE complexes, to create a nanocompartment depend on the cAMP degradation rate, the diffusive mobility of cAMP, and geometrical and topological parameters. We apply these generic models to our experimental data and determine the diffusive mobility and degradation rate of cAMP. The results obtained for these parameters differ by far from data in literature for free soluble cAMP interacting with PDE. Hence, restricted cAMP diffusion in the vincinity of PDE is necessary to create cAMP nanocompartments in cells.},
  language  = {en}
}
@article{SchuppStopperHeidland2016,
  author    = {Schupp, Nicole and Stopper, Helga and Heidland, August},
  title     = {DNA Damage in Chronic Kidney Disease: Evaluation of Clinical Biomarkers},
  series = {Oxidative Medicine and Cellular Longevity},
  volume    = {2016},
  journal   = {Oxidative Medicine and Cellular Longevity},
  number    = {3592042},
  doi       = {10.1155/2016/3592042},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-166569},
  year      = {2016},
  abstract  = {Patients with chronic kidney disease (CKD) exhibit an increased cancer risk compared to a healthy control population. To be able to estimate the cancer risk of the patients and to assess the impact of interventional therapies thereon, it is of particular interest to measure the patients' burden of genomic damage. Chromosomal abnormalities, reduced DNA repair, and DNA lesions were found indeed in cells of patients with CKD. Biomarkers for DNA damage measurable in easily accessible cells like peripheral blood lymphocytes are chromosomal aberrations, structural DNA lesions, and oxidatively modified DNA bases. In this review the most common methods quantifying the three parameters mentioned above, the cytokinesis-block micronucleus assay, the comet assay, and the quantification of 8-oxo-7,8-dihydro-2′-deoxyguanosine, are evaluated concerning the feasibility of the analysis and regarding the marker's potential to predict clinical outcomes.},
  language  = {en}
}
@article{FathyFawzyHintzscheetal.2019,
  author    = {Fathy, Moustafa and Fawzy, Michael Atef and Hintzsche, Henning and Nikaido, Toshio and Dandekar, Thomas and Othman, Eman M.},
  title     = {Eugenol exerts apoptotic effect and modulates the sensitivity of HeLa cells to cisplatin and radiation},
  series = {Molecules},
  volume    = {24},
  journal   = {Molecules},
  number    = {21},
  issn      = {1420-3049},
  doi       = {10.3390/molecules24213979},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-193227},
  pages     = {3979},
  year      = {2019},
  abstract  = {Eugenol is a phytochemical present in different plant products, e.g., clove oil. Traditionally, it is used against a number of different disorders and it was suggested to have anticancer activity. In this study, the activity of eugenol was evaluated in a human cervical cancer (HeLa) cell line and cell proliferation was examined after treatment with various concentrations of eugenol and different treatment durations. Cytotoxicity was tested using lactate dehydrogenase (LDH) enzyme leakage. In order to assess eugenol's potential to act synergistically with chemotherapy and radiotherapy, cell survival was calculated after eugenol treatment in combination with cisplatin and X-rays. To elucidate its mechanism of action, caspase-3 activity was analyzed and the expression of various genes and proteins was checked by RT-PCR and western blot analyses. Eugenol clearly decreased the proliferation rate and increased LDH release in a concentration- and time-dependent manner. It showed synergistic effects with cisplatin and X-rays. Eugenol increased caspase-3 activity and the expression of Bax, cytochrome c (Cyt-c), caspase-3, and caspase-9 and decreased the expression of B-cell lymphoma (Bcl)-2, cyclooxygenase-2 (Cox-2), and interleukin-1 beta (IL-1β) indicating that eugenol mainly induced cell death by apoptosis. In conclusion, eugenol showed antiproliferative and cytotoxic effects via apoptosis and also synergism with cisplatin and ionizing radiation in the human cervical cancer cell line.},
  language  = {en}
}
@article{WoelfelSaetteleZechmeisteretal.2020,
  author    = {W{\"o}lfel, Angela and S{\"a}ttele, Mathias and Zechmeister, Christina and Nikolaev, Viacheslov O. and Lohse, Martin J. and Boege, Fritz and Jahns, Roland and Boivin-Jahns, Val{\´e}rie},
  title     = {Unmasking features of the auto-epitope essential for β\(_1\)-adrenoceptor activation by autoantibodies in chronic heart failure},
  series = {ESC Heart Failure},
  volume    = {7},
  journal   = {ESC Heart Failure},
  number    = {4},
  doi       = {10.1002/ehf2.12747},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-235974},
  pages     = {1830-1841},
  year      = {2020},
  abstract  = {Aims Chronic heart failure (CHF) can be caused by autoantibodies stimulating the heart via binding to first and/or second extracellular loops of cardiac β1-adrenoceptors. Allosteric receptor activation depends on conformational features of the autoantibody binding site. Elucidating these features will pave the way for the development of specific diagnostics and therapeutics. Our aim was (i) to fine-map the conformational epitope within the second extracellular loop of the human β\(_1\)-adrenoceptor (β1ECII) that is targeted by stimulating β\(_1\)-receptor (auto)antibodies and (ii) to generate competitive cyclopeptide inhibitors of allosteric receptor activation, which faithfully conserve the conformational auto-epitope. Methods and results Non-conserved amino acids within the β\(_1\)EC\(_{II}\) loop (compared with the amino acids constituting the ECII loop of the β\(_2\)-adrenoceptor) were one by one replaced with alanine; potential intra-loop disulfide bridges were probed by cysteine-serine exchanges. Effects on antibody binding and allosteric receptor activation were assessed (i) by (auto)antibody neutralization using cyclopeptides mimicking β1ECII ± the above replacements, and (ii) by (auto)antibody stimulation of human β\(_1\)-adrenoceptors bearing corresponding point mutations. With the use of stimulating β\(_1\)-receptor (auto)antibodies raised in mice, rats, or rabbits and isolated from exemplary dilated cardiomyopathy patients, our series of experiments unmasked two features of the β\(_1\)EC\(_{II}\) loop essential for (auto)antibody binding and allosteric receptor activation: (i) the NDPK\(^{211-214}\) motif and (ii) the intra-loop disulfide bond C\(^{209}\)↔C\(^{215}\). Of note, aberrant intra-loop disulfide bond C\(^{209}\)↔C\(^{216}\) almost fully disrupted the functional auto-epitope in cyclopeptides. Conclusions The conformational auto-epitope targeted by cardio-pathogenic β\(_1\)-receptor autoantibodies is faithfully conserved in cyclopeptide homologues of the β\(_1\)EC\(_{II}\) loop bearing the NDPK\(^{211-214}\) motif and the C\(^{209}\)↔C\(^{215}\) bridge while lacking cysteine C216. Such molecules provide promising tools for novel diagnostic and therapeutic approaches in β\(_1\)-autoantibodypositive CHF.},
  language  = {en}
}
@article{ScholzGuanNieberleretal.2017,
  author    = {Scholz, Nicole and Guan, Chonglin and Nieberler, Matthias and Grotmeyer, Alexander and Maiellaro, Isabella and Gao, Shiqiang and Beck, Sebastian and Pawlak, Matthias and Sauer, Markus and Asan, Esther and Rothemund, Sven and Winkler, Jana and Pr{\"o}mel, Simone and Nagel, Georg and Langenhan, Tobias and Kittel, Robert J},
  title     = {Mechano-dependent signaling by Latrophilin/CIRL quenches cAMP in proprioceptive neurons},
  series = {eLife},
  volume    = {6},
  journal   = {eLife},
  number    = {e28360},
  doi       = {10.7554/eLife.28360},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170520},
  year      = {2017},
  abstract  = {Adhesion-type G protein-coupled receptors (aGPCRs), a large molecule family with over 30 members in humans, operate in organ development, brain function and govern immunological responses. Correspondingly, this receptor family is linked to a multitude of diverse human diseases. aGPCRs have been suggested to possess mechanosensory properties, though their mechanism of action is fully unknown. Here we show that the Drosophila aGPCR Latrophilin/dCIRL acts in mechanosensory neurons by modulating ionotropic receptor currents, the initiating step of cellular mechanosensation. This process depends on the length of the extended ectodomain and the tethered agonist of the receptor, but not on its autoproteolysis, a characteristic biochemical feature of the aGPCR family. Intracellularly, dCIRL quenches cAMP levels upon mechanical activation thereby specifically increasing the mechanosensitivity of neurons. These results provide direct evidence that the aGPCR dCIRL acts as a molecular sensor and signal transducer that detects and converts mechanical stimuli into a metabotropic response.},
  language  = {en}
}
@article{GmachBathePetersTeluguetal.2022,
  author    = {Gmach, Philipp and Bathe-Peters, Marc and Telugu, Narasimha and Miller, Duncan C. and Annibale, Paolo},
  title     = {Fluorescence spectroscopy of low-level endogenous β-adrenergic receptor expression at the plasma membrane of differentiating human iPSC-derived cardiomyocytes},
  series = {International Journal of Molecular Sciences},
  volume    = {23},
  journal   = {International Journal of Molecular Sciences},
  number    = {18},
  issn      = {1422-0067},
  doi       = {10.3390/ijms231810405},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-288277},
  year      = {2022},
  abstract  = {The potential of human-induced pluripotent stem cells (hiPSCs) to be differentiated into cardiomyocytes (CMs) mimicking adult CMs functional morphology, marker genes and signaling characteristics has been investigated since over a decade. The evolution of the membrane localization of CM-specific G protein-coupled receptors throughout differentiation has received, however, only limited attention to date. We employ here advanced fluorescent spectroscopy, namely linescan Fluorescence Correlation Spectroscopy (FCS), to observe how the plasma membrane abundance of the β\(_1\)- and β\(_2\)-adrenergic receptors (β\(_{1/2}\)-ARs), labelled using a bright and photostable fluorescent antagonist, evolves during the long-term monolayer culture of hiPSC-derived CMs. We compare it to the kinetics of observed mRNA levels in wildtype (WT) hiPSCs and in two CRISPR/Cas9 knock-in clones. We conduct these observations against the backdrop of our recent report of cell-to-cell expression variability, as well as of the subcellular localization heterogeneity of β-ARs in adult CMs.},
  language  = {en}
}
@article{SchanbacherHermannsLorenzetal.2023,
  author    = {Schanbacher, Constanze and Hermanns, Heike M. and Lorenz, Kristina and Wajant, Harald and Lang, Isabell},
  title     = {Complement 1q/tumor necrosis factor-related proteins (CTRPs): structure, receptors and signaling},
  series = {Biomedicines},
  volume    = {11},
  journal   = {Biomedicines},
  number    = {2},
  issn      = {2227-9059},
  doi       = {10.3390/biomedicines11020559},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-304136},
  year      = {2023},
  abstract  = {Adiponectin and the other 15 members of the complement 1q (C1q)/tumor necrosis factor (TNF)-related protein (CTRP) family are secreted proteins composed of an N-terminal variable domain followed by a stalk region and a characteristic C-terminal trimerizing globular C1q (gC1q) domain originally identified in the subunits of the complement protein C1q. We performed a basic PubMed literature search for articles mentioning the various CTRPs or their receptors in the abstract or title. In this narrative review, we briefly summarize the biology of CTRPs and focus then on the structure, receptors and major signaling pathways of CTRPs. Analyses of CTRP knockout mice and CTRP transgenic mice gave overwhelming evidence for the relevance of the anti-inflammatory and insulin-sensitizing effects of CTRPs in autoimmune diseases, obesity, atherosclerosis and cardiac dysfunction. CTRPs form homo- and heterotypic trimers and oligomers which can have different activities. The receptors of some CTRPs are unknown and some receptors are redundantly targeted by several CTRPs. The way in which CTRPs activate their receptors to trigger downstream signaling pathways is largely unknown. CTRPs and their receptors are considered as promising therapeutic targets but their translational usage is still hampered by the limited knowledge of CTRP redundancy and CTRP signal transduction.},
  language  = {en}
}
@article{JanzWalzCirnuetal.2024,
  author    = {Janz, Anna and Walz, Katharina and Cirnu, Alexandra and Surjanto, Jessica and Urlaub, Daniela and Leskien, Miriam and Kohlhaas, Michael and Nickel, Alexander and Brand, Theresa and Nose, Naoko and W{\"o}rsd{\"o}rfer, Philipp and Wagner, Nicole and Higuchi, Takahiro and Maack, Christoph and Dudek, Jan and Lorenz, Kristina and Klopocki, Eva and Erg{\"u}n, S{\"u}leyman and Duff, Henry J. and Gerull, Brenda},
  title     = {Mutations in DNAJC19 cause altered mitochondrial structure and increased mitochondrial respiration in human iPSC-derived cardiomyocytes},
  series = {Molecular Metabolism},
  volume    = {79},
  journal   = {Molecular Metabolism},
  issn      = {2212-8778},
  doi       = {10.1016/j.molmet.2023.101859},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-350393},
  year      = {2024},
  abstract  = {Highlights • Loss of DNAJC19's DnaJ domain disrupts cardiac mitochondrial structure, leading to abnormal cristae formation in iPSC-CMs. • Impaired mitochondrial structures lead to an increased mitochondrial respiration, ROS and an elevated membrane potential. • Mutant iPSC-CMs show sarcomere dysfunction and a trend to more arrhythmias, resembling DCMA-associated cardiomyopathy. Background Dilated cardiomyopathy with ataxia (DCMA) is an autosomal recessive disorder arising from truncating mutations in DNAJC19, which encodes an inner mitochondrial membrane protein. Clinical features include an early onset, often life-threatening, cardiomyopathy associated with other metabolic features. Here, we aim to understand the metabolic and pathophysiological mechanisms of mutant DNAJC19 for the development of cardiomyopathy. Methods We generated induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) of two affected siblings with DCMA and a gene-edited truncation variant (tv) of DNAJC19 which all lack the conserved DnaJ interaction domain. The mutant iPSC-CMs and their respective control cells were subjected to various analyses, including assessments of morphology, metabolic function, and physiological consequences such as Ca\(^{2+}\) kinetics, contractility, and arrhythmic potential. Validation of respiration analysis was done in a gene-edited HeLa cell line (DNAJC19tv\(_{HeLa}\)). Results Structural analyses revealed mitochondrial fragmentation and abnormal cristae formation associated with an overall reduced mitochondrial protein expression in mutant iPSC-CMs. Morphological alterations were associated with higher oxygen consumption rates (OCRs) in all three mutant iPSC-CMs, indicating higher electron transport chain activity to meet cellular ATP demands. Additionally, increased extracellular acidification rates suggested an increase in overall metabolic flux, while radioactive tracer uptake studies revealed decreased fatty acid uptake and utilization of glucose. Mutant iPSC-CMs also showed increased reactive oxygen species (ROS) and an elevated mitochondrial membrane potential. Increased mitochondrial respiration with pyruvate and malate as substrates was observed in mutant DNAJC19tv HeLa cells in addition to an upregulation of respiratory chain complexes, while cellular ATP-levels remain the same. Moreover, mitochondrial alterations were associated with increased beating frequencies, elevated diastolic Ca\(^{2+}\) concentrations, reduced sarcomere shortening and an increased beat-to-beat rate variability in mutant cell lines in response to β-adrenergic stimulation. Conclusions Loss of the DnaJ domain disturbs cardiac mitochondrial structure with abnormal cristae formation and leads to mitochondrial dysfunction, suggesting that DNAJC19 plays an essential role in mitochondrial morphogenesis and biogenesis. Moreover, increased mitochondrial respiration, altered substrate utilization, increased ROS production and abnormal Ca\(^{2+}\) kinetics provide insights into the pathogenesis of DCMA-related cardiomyopathy.},
  language  = {en}
}
@article{GuthHueserRothetal.2021,
  author    = {Guth, Sabine and H{\"u}ser, Stephanie and Roth, Angelika and Degen, Gisela and Diel, Patrick and Edlund, Karolina and Eisenbrand, Gerhard and Engel, Karl-Heinz and Epe, Bernd and Grune, Tilman and Heinz, Volker and Henle, Thomas and Humpf, Hans-Ulrich and J{\"a}ger, Henry and Joost, Hans-Georg and Kulling, Sabine E. and Lampen, Alfonso and Mally, Angela and Marchan, Rosemarie and Marko, Doris and M{\"u}hle, Eva and Nitsche, Michael A. and R{\"o}hrdanz, Elke and Stadler, Richard and van Thriel, Christoph and Vieths, Stefan and Vogel, Rudi F. and Wascher, Edmund and Watzl, Carsten and N{\"o}thlings, Ute and Hengstler, Jan G.},
  title     = {Contribution to the ongoing discussion on fluoride toxicity},
  series = {Archives of Toxicology},
  volume    = {95},
  journal   = {Archives of Toxicology},
  number    = {7},
  issn      = {0340-5761},
  doi       = {10.1007/s00204-021-03072-6},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-307161},
  pages     = {2571-2587},
  year      = {2021},
  abstract  = {Since the addition of fluoride to drinking water in the 1940s, there have been frequent and sometimes heated discussions regarding its benefits and risks. In a recently published review, we addressed the question if current exposure levels in Europe represent a risk to human health. This review was discussed in an editorial asking why we did not calculate benchmark doses (BMD) of fluoride neurotoxicity for humans. Here, we address the question, why it is problematic to calculate BMDs based on the currently available data. Briefly, the conclusions of the available studies are not homogeneous, reporting negative as well as positive results; moreover, the positive studies lack control of confounding factors such as the influence of well-known neurotoxicants. We also discuss the limitations of several further epidemiological studies that did not meet the inclusion criteria of our review. Finally, it is important to not only focus on epidemiological studies. Rather, risk analysis should consider all available data, including epidemiological, animal, as well as in vitro studies. Despite remaining uncertainties, the totality of evidence does not support the notion that fluoride should be considered a human developmental neurotoxicant at current exposure levels in European countries.},
  language  = {en}
}
@article{BarileBerryBlaauboeretal.2021,
  author    = {Barile, Frank A. and Berry, Colin and Blaauboer, Bas and Boobis, Alan and Bolt, Herrmann M. and Borgert, Christopher and Dekant, Wolfgang and Dietrich, Daniel and Domingo, Jose L. and Galli, Corrado L. and Gori, Gio Batta and Greim, Helmut and Hengstler, Jan G. and Heslop-Harrison, Pat and Kacew, Sam and Marquardt, Hans and Mally, Angela and Pelkonen, Olavi and Savolainen, Kai and Testai, Emanuela and Tsatsakis, Aristides and Vermeulen, Nico P.},
  title     = {The EU chemicals strategy for sustainability: in support of the BfR position},
  series = {Archives of Toxicology},
  volume    = {95},
  journal   = {Archives of Toxicology},
  number    = {9},
  issn      = {0340-5761},
  doi       = {10.1007/s00204-021-03125-w},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-307154},
  pages     = {3133-3136},
  year      = {2021},
  abstract  = {The EU chemicals strategy for sustainability (CSS) asserts that both human health and the environment are presently threatened and that further regulation is necessary. In a recent Guest Editorial, members of the German competent authority for risk assessment, the BfR, raised concerns about the scientific justification for this strategy. The complexity and interdependence of the networks of regulation of chemical substances have ensured that public health and wellbeing in the EU have continuously improved. A continuous process of improvement in consumer protection is clearly desirable but any initiative directed towards this objective must be based on scientific knowledge. It must not confound risk with other factors in determining policy. This conclusion is fully supported in the present Commentary including the request to improve both, data collection and the time-consuming and bureaucratic procedures that delay the publication of regulations.},
  language  = {en}
}
@article{RebsStreckfussBoemeke2023,
  author    = {Rebs, Sabine and Streckfuss-B{\"o}meke, Katrin},
  title     = {How can we use stem cell-derived cardiomyocytes to understand the involvement of energetic metabolism in alterations of cardiac function?},
  series = {Frontiers in Molecular Medicine},
  volume    = {3},
  journal   = {Frontiers in Molecular Medicine},
  doi       = {10.3389/fmmed.2023.1222986},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-327344},
  year      = {2023},
  abstract  = {Mutations in the mitochondrial-DNA or mitochondria related nuclear-encoded-DNA lead to various multisystemic disorders collectively termed mitochondrial diseases. One in three cases of mitochondrial disease affects the heart muscle, which is called mitochondrial cardiomyopathy (MCM) and is associated with hypertrophic, dilated, and noncompact cardiomyopathy. The heart is an organ with high energy demand, and mitochondria occupy 30\%-40\% of its cardiomyocyte-cell volume. Mitochondrial dysfunction leads to energy depletion and has detrimental effects on cardiac performance. However, disease development and progression in the context of mitochondrial and nuclear DNA mutations, remains incompletely understood. The system of induced pluripotent stem cell (iPSC)-derived cardiomyocytes (CM) is an excellent platform to study MCM since the unique genetic identity to their donors enables a robust recapitulation of the predicted phenotypes in a dish on a patient-specific level. Here, we focus on recent insights into MCM studied by patient-specific iPSC-CM and further discuss research gaps and advances in metabolic maturation of iPSC-CM, which is crucial for the study of mitochondrial dysfunction and to develop novel therapeutic strategies.},
  language  = {en}
}
@unpublished{BrennerZinkWitzingeretal.2024,
  author    = {Brenner, Marian and Zink, Christoph and Witzinger, Linda and Keller, Angelika and Hadamek, Kerstin and Bothe, Sebastian and Neuenschwander, Martin and Villmann, Carmen and von Kries, Jens Peter and Schindelin, Hermann and Jeanclos, Elisabeth and Gohla, Antje},
  title     = {7,8-Dihydroxyflavone is a direct inhibitor of pyridoxal phosphatase},
  series = {eLife},
  journal   = {eLife},
  doi       = {10.7554/eLife.93094.2},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-350446},
  year      = {2024},
  abstract  = {Vitamin B6 deficiency has been linked to cognitive impairment in human brain disorders for decades. Still, the molecular mechanisms linking vitamin B6 to these pathologies remain poorly understood, and whether vitamin B6 supplementation improves cognition is unclear as well. Pyridoxal phosphatase (PDXP), an enzyme that controls levels of pyridoxal 5'-phosphate (PLP), the co-enzymatically active form of vitamin B6, may represent an alternative therapeutic entry point into vitamin B6-associated pathologies. However, pharmacological PDXP inhibitors to test this concept are lacking. We now identify a PDXP and age-dependent decline of PLP levels in the murine hippocampus that provides a rationale for the development of PDXP inhibitors. Using a combination of small molecule screening, protein crystallography and biolayer interferometry, we discover and analyze 7,8-dihydroxyflavone (7,8-DHF) as a direct and potent PDXP inhibitor. 7,8-DHF binds and reversibly inhibits PDXP with low micromolar affinity and sub-micromolar potency. In mouse hippocampal neurons, 7,8-DHF increases PLP in a PDXP-dependent manner. These findings validate PDXP as a druggable target. Of note, 7,8-DHF is a well-studied molecule in brain disorder models, although its mechanism of action is actively debated. Our discovery of 7,8-DHF as a PDXP inhibitor offers novel mechanistic insights into the controversy surrounding 7,8-DHF-mediated effects in the brain.},
  language  = {en}
}
@article{DjelićBorozanDimitrijevićSrećkovićetal.2022,
  author    = {Djelić, Ninoslav and Borozan, Sunčica and Dimitrijević-Srećković, Vesna and Pajović, Nevena and Mirilović, Milorad and Stopper, Helga and Stanimirović, Zoran},
  title     = {Oxidative stress and DNA damage in peripheral blood mononuclear cells from normal, obese, prediabetic and diabetic persons exposed to thyroid hormone in vitro},
  series = {International Journal of Molecular Sciences},
  volume    = {23},
  journal   = {International Journal of Molecular Sciences},
  number    = {16},
  issn      = {1422-0067},
  doi       = {10.3390/ijms23169072},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-285988},
  year      = {2022},
  abstract  = {Diabetes, a chronic group of medical disorders characterized byhyperglycemia, has become a global pandemic. Some hormones may influence the course and outcome of diabetes, especially if they potentiate the formation of reactive oxygen species (ROS). There is a close relationship between thyroid disorders and diabetes. The main objective of this investigation was to find out whether peripheral blood mononuclear cells (PBMCs) are more prone to DNA damage by triiodothyronine (T\(_3\)) (0.1, 1 and 10 μM) at various stages of progression through diabetes (obese, prediabetics, and type 2 diabetes mellitus—T2DM persons). In addition, some biochemical parameters of oxidative stress (catalase-CAT, thiobarbituric acid reactive substances—TBARS) and lactate dehydrogenase (LDH) were evaluated. PBMCs from prediabetic and diabetic patients exhibited increased sensitivity for T\(_3\) regarding elevated level of DNA damage, inhibition of catalase, and increase of TBARS and LDH. PBMCs from obese patients reacted in the same manner, except for DNA damage. The results of this study should contribute to a better understanding of the role of thyroid hormones in the progression of T2DM.},
  language  = {en}
}
@phdthesis{Horn2024,
  author    = {Horn, Daniela},
  title     = {Kardiotoxizit{\"a}t von CTRPs und das Vorkommen der CTRP-Rezeptoren in Kardiomyozyten},
  doi       = {10.25972/OPUS-34902},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-349029},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2024},
  abstract  = {Die C1q/tumor necrosis factor-related proteins (CTRPs) sind eine Ligandenfamilie aus sezernierten Plasmaproteinen, welche sich in ihrem Grundbauplan {\"a}hneln. Daten aus der Literatur deuten darauf hin, dass sie zum Teil positive Effekte auf den Stoffwechsel und das Herz-Kreislaufsystem besitzen und somit eine m{\"o}gliche therapeutische Zielstruktur darstellen. W{\"a}hrend f{\"u}r manche CTRPs bereits Rezeptoren identifiziert werden konnten, ist f{\"u}r andere immer noch nicht gekl{\"a}rt, an welche Rezeptoren sie binden oder {\"u}ber welche sie diese Wirkungen erzielen. Um die CTRPs zuk{\"u}nftig therapeutisch nutzen zu k{\"o}nnen, muss die Wirkung der CTRPs auf verschiedene Zellen weiter analysiert werden. Daf{\"u}r wurden in dieser Arbeit Zellen, auf die Expression bereits bekannter CTRP-Rezeptoren hin, untersucht. Des Weiteren wurden die durch CTRP2, CTRP3, CTRP4, CTRP9A, CTRP10, CTRP11, CTRP13 und CTRP14 induzierten {\"A}nderungen in der ATP- und Laktatproduktion als Surrogatparameter f{\"u}r Kardiotoxizit{\"a}t in den Kardiomyozytenzelllinien H9c2 und AC16 getestet, um potenziell kardiotoxische Wirkungen fr{\"u}hzeitig erkennen zu k{\"o}nnen. Es konnte gezeigt werden, dass die CTRPs sicher f{\"u}r Kardiomyozyten zu sein scheinen, was eine wichtige Grundlage f{\"u}r die therapeutische Nutzbarkeit darstellt.},
  subject      = {Herzmuskelzelle},
  language  = {de}
}
@article{EberlRebsHoppeetal.2024,
  author    = {Eberl, Hanna and Rebs, Sabine and Hoppe, Stefanie and Sedaghat-Hamedani, Farbod and Kayvanpour, Elham and Meder, Benjamin and Streckfuss-B{\"o}meke, Katrin},
  title     = {Generation of an RBM20-mutation-associated left-ventricular non-compaction cardiomyopathy iPSC line (UMGi255-A) into a DCM genetic background to investigate monogenetic cardiomyopathies},
  series = {Stem Cell Research},
  volume    = {74},
  journal   = {Stem Cell Research},
  issn      = {1873-5061},
  doi       = {10.1016/j.scr.2023.103290},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-350565},
  year      = {2024},
  abstract  = {RBM20 mutations account for 3 \% of genetic cardiomypathies and manifest with high penetrance and arrhythmogenic effects. Numerous mutations in the conserved RS domain have been described as causing dilated cardiomyopathy (DCM), whereas a particular mutation (p.R634L) drives development of a different cardiac phenotype: left-ventricular non-compaction cardiomyopathy. We generated a mutation-induced pluripotent stem cell (iPSC) line in which the RBM20-LVNC mutation p.R634L was introduced into a DCM patient line with rescued RBM20-p.R634W mutation. These DCM-634L-iPSC can be differentiated into functional cardiomyocytes to test whether this RBM20 mutation induces development of the LVNC phenotype within the genetic context of a DCM patient.},
  language  = {en}
}
@article{BankogluStippGerberetal.2021,
  author    = {Bankoglu, Ezgi Eyluel and Stipp, Franzisca and Gerber, Johanna and Seyfried, Florian and Heidland, August and Bahner, Udo and Stopper, Helga},
  title     = {Effect of cryopreservation on DNA damage and DNA repair activity in human blood samples in the comet assay},
  series = {Archives of Toxicology},
  volume    = {95},
  journal   = {Archives of Toxicology},
  number    = {5},
  doi       = {10.1007/s00204-021-03012-4},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-265326},
  pages     = {1831-1841},
  year      = {2021},
  abstract  = {The comet assay is a commonly used method to determine DNA damage and repair activity in many types of samples. In recent years, the use of the comet assay in human biomonitoring became highly attractive due to its various modified versions, which may be useful to determine individual susceptibility in blood samples. However, in human biomonitoring studies, working with large sample numbers that are acquired over an extended time period requires some additional considerations. One of the most important issues is the storage of samples and its effect on the outcome of the comet assay. Another important question is the suitability of different blood preparations. In this study, we analysed the effect of cryopreservation on DNA damage and repair activity in human blood samples. In addition, we investigated the suitability of different blood preparations. The alkaline and FPG as well as two different types of repair comet assay and an in vitro hydrogen peroxide challenge were applied. Our results confirmed that cryopreserved blood preparations are suitable for investigating DNA damage in the alkaline and FPG comet assay in whole blood, buffy coat and PBMCs. Ex vivo hydrogen peroxide challenge yielded its optimal effect in isolated PBMCs. The utilised repair comet assay with either UVC or hydrogen peroxide-induced lesions and an aphidicolin block worked well in fresh PBMCs. Cryopreserved PBMCs could not be used immediately after thawing. However, a 16-h recovery with or without mitotic stimulation enabled the application of the repair comet assay, albeit only in a surviving cell fraction.},
  language  = {en}
}
@article{ChristianSeierDrakopoulosetal.2020,
  author    = {Christian, Gentzsch and Seier, Kerstin and Drakopoulos, Antonios and Jobin, Marie-Lise and Lanoisel{\´e}e, Yann and Koszegi, Zsombor and Maurel, Damien and Sounier, R{\´e}my and H{\"u}bner, Harald and Gmeiner, Peter and Granier, S{\´e}bastien and Calebiro, Davide and Decker, Michael},
  title     = {Selective and Wash-Resistant Fluorescent Dihydrocodeinone Derivatives Allow Single-Molecule Imaging of μ-Opioid Receptor Dimerization},
  series = {Angewandte Chemie International Edition},
  volume    = {59},
  journal   = {Angewandte Chemie International Edition},
  number    = {15},
  doi       = {10.1002/anie.201912683},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-212398},
  pages     = {5958-5964},
  year      = {2020},
  abstract  = {μ-Opioid receptors (μ-ORs) play a critical role in the modulation of pain and mediate the effects of the most powerful analgesic drugs. Despite extensive efforts, it remains insufficiently understood how μ-ORs produce specific effects in living cells. We developed new fluorescent ligands based on the μ-OR antagonist E-p-nitrocinnamoylamino-dihydrocodeinone (CACO), that display high affinity, long residence time and pronounced selectivity. Using these ligands, we achieved single-molecule imaging of μ-ORs on the surface of living cells at physiological expression levels. Our results reveal a high heterogeneity in the diffusion of μ-ORs, with a relevant immobile fraction. Using a pair of fluorescent ligands of different color, we provide evidence that μ-ORs interact with each other to form short-lived homodimers on the plasma membrane. This approach provides a new strategy to investigate μ-OR pharmacology at single-molecule level.},
  language  = {en}
}
@article{GodboleLygaLohseetal.2017,
  author    = {Godbole, Amod and Lyga, Sandra and Lohse, Martin J. and Calebiro, Davide},
  title     = {Internalized TSH receptors en route to the TGN induce local G\(_{S}\)-protein signaling and gene transcription},
  series = {Nature Communications},
  volume    = {8},
  journal   = {Nature Communications},
  number    = {443},
  doi       = {10.1038/s41467-017-00357-2},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-170375},
  year      = {2017},
  abstract  = {A new paradigm of G-protein-coupled receptor (GPCR) signaling at intracellular sites has recently emerged, but the underlying mechanisms and functional consequences are insufficiently understood. Here, we show that upon internalization in thyroid cells, endogenous TSH receptors traffic retrogradely to the trans-Golgi network (TGN) and activate endogenous Gs-proteins in the retromer-coated compartment that brings them to the TGN. Receptor internalization is associated with a late cAMP/protein kinase A (PKA) response at the Golgi/TGN. Blocking receptor internalization, inhibiting PKA II/interfering with its Golgi/TGN localization, silencing retromer or disrupting Golgi/TGN organization all impair efficient TSH-dependent cAMP response element binding protein (CREB) phosphorylation. These results suggest that retrograde trafficking to the TGN induces local G\(_{S}\)-protein activation and cAMP/PKA signaling at a critical position near the nucleus, which appears required for efficient CREB phosphorylation and gene transcription. This provides a new mechanism to explain the functional consequences of GPCR signaling at intracellular sites and reveals a critical role for the TGN in GPCR signaling.},
  language  = {en}
}
@article{MaurerHuppBischoffetal.2017,
  author    = {Maurer, Jana and Hupp, Sabrina and Bischoff, Carolin and Foertsch, Christina and Mitchell, Timothy J. and Chakraborty, Trinad and Iliev, Asparouh I.},
  title     = {Distinct neurotoxicity profile of listeriolysin O from \(Listeria\) \(monocytogenes\)},
  series = {Toxins},
  volume    = {9},
  journal   = {Toxins},
  number    = {1},
  doi       = {10.3390/toxins9010034},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172130},
  year      = {2017},
  abstract  = {Cholesterol-dependent cytolysins (CDCs) are protein toxins that originate from Gram-positive bacteria and contribute substantially to their pathogenicity. CDCs bind membrane cholesterol and build prepores and lytic pores. Some effects of the toxins are observed in non-lytic concentrations. Two pathogens, \(Streptococcus\) \(pneumoniae\) and \(Listeria\) \(monocytogenes\), cause fatal bacterial meningitis, and both produce toxins of the CDC family—pneumolysin and listeriolysin O, respectively. It has been demonstrated that pneumolysin produces dendritic varicosities (dendrite swellings) and dendritic spine collapse in the mouse neocortex, followed by synaptic loss and astrocyte cell shape remodeling without elevated cell death. We utilized primary glial cultures and acute mouse brain slices to examine the neuropathological effects of listeriolysin O and to compare it to pneumolysin with identical hemolytic activity. In cultures, listeriolysin O permeabilized cells slower than pneumolysin did but still initiated non-lytic astrocytic cell shape changes, just as pneumolysin did. In an acute brain slice culture system, listeriolysin O produced dendritic varicosities in an NMDA-dependent manner but failed to cause dendritic spine collapse and cortical astrocyte reorganization. Thus, listeriolysin O demonstrated slower cell permeabilization and milder glial cell remodeling ability than did pneumolysin and lacked dendritic spine collapse capacity but exhibited equivalent dendritic pathology.},
  language  = {en}
}
@phdthesis{Cirkel2018,
  author    = {Cirkel, Nanett Christin},
  title     = {Beeinflussung des oxidativen Stress-Status in einem Rattenmodell: Effekt von Selenmangel auf Niere und Leber},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-163631},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {Das Spurenelement Selen und Vitamin E reduzieren reaktive Sauerstoff Spezies (ROS). Bei Mangel dieser wichtigen Stoffe erh{\"o}ht sich die Konzentration an ROS und der oxidative Stress steigt. Unter erh{\"o}hten ROS entstehen vermehrt DNA-Sch{\"a}den und Lipidperoxidationen. Das ROS Wasserstoffperoxid wird zu Wasser {\"u}ber das Enzym Gluthationperxoidase reduziert. Dessen Aktivit{\"a}t steigert Selen um den Faktor 100-1.000. Das Aktivit{\"a}tsmaximum des Enzyms liegt bei einer t{\"a}glichen Selenaufnahme von 60-80 Mikrogramm/Tag. Dadurch wird die Menge an ROS reduziert und der oxidative Stress in der Zelle nimmt ab. Vitamin E fungiert als Radikalf{\"a}nger. Sein Derivat alpha- Tocopherol besitzt die h{\"o}chste antioxidative Wirkung und kann Lipidperoxidationen unterbrechen. Die vorliegende Arbeit untersucht Auswirkungen von oxidativem Stress, den ein Mangel von Selen und Vitamin E in der Nahrung bei 6 Monate und 12 Monate alten Tieren auf Leber und Niere verursacht. Der Nachweis von oxidativem Stress erfolgte {\"u}ber sogenannte Hitzeschockproteine HSP70 und H{\"a}moxygenase 1. HSP 70 wird auch unter physiologischen Bedingungen exprimiert. Es wirkt als Chaperon und ist u.a. f{\"u}r die korrekte Faltung und Stabilisierung von Proteinen zust{\"a}ndig. Die Versuche zeigten, dass im Alter in der Niere die HSP70 Konzentration ansteigt und die Zelle unter vermehrtem oxidativen Stress leidet. Entsprechende Literaturergebnisse wurden best{\"a}tigt. Die H{\"a}moxygenase 1 (HO-1) ist ein Schl{\"u}sselenzym, das vermehrt bei oxidativem Stress gebildet wird. Hoch reaktionsfreudige und freie Blutbestandteile katalysiert die H{\"a}moxygenase. Einen Abfall der HO- 1 Konzentration zeigten Untersuchungen von Leber und Niere bei Selen, - Vitamin E Mangel und h{\"o}herem Lebensalter. Gr{\"u}nde f{\"u}r die verminderte Expression sind noch wenig erforscht. Die vermehrte Anreicherung von Superoxidanionradikalen wurde in den Geweben von Leber und Niere {\"u}ber Dihydroethidium (DHE) F{\"a}rbung nachgewiesen. Die Hypothese wurde best{\"a}tigt, dass bei Selen, -Vitamin E Mangelnahrung und h{\"o}herem Alter vermehrter oxidativer Stress entsteht. Selenmangel beg{\"u}nstigt die Entstehung verschiedener Krankheiten, z.B. Krebs, koronale Herzerkrankung und vor allem die Keshan-Krankheit, die den Herzmuskel bef{\"a}llt. Selen nimmt positiven Einfluss auf K{\"o}rperfunktionen: Fertilit{\"a}t, embryonalen Entwicklung und Entwicklung eines Neugeborenen. Einige Fragen bleiben ungekl{\"a}rt: Welche physiologischen Entwicklungsprozesse f{\"o}rdert Selen? Nimmt Selen eine wichtige Funktion bei der Befruchtung der Eizelle ein? Wie beeinflusst Selen die Entwicklung des Gehirns? Dem Spurenelement Selen kommen offensichtlich neben seiner Bedeutung zur Minderung des oxidativen Stresses noch weitere wichtige Funktionen zu, die bisher wenig untersucht wurden.},
  subject      = {Oxidativer Stress},
  language  = {de}
}
@phdthesis{Soliman2022,
  author    = {Soliman, Alexander},
  title     = {Einfluss des Gewichtsverlusts auf den oxidativen Stress und den DNS-Schaden in adip{\"o}sen Patient*innen nach bariatrischer Chirurgie},
  doi       = {10.25972/OPUS-27835},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-278354},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {Adipositas ist eine Erkrankung, die durch ein erh{\"o}htes Krebsrisiko neben zahlreichen anderen Komorbidit{\"a}ten mit weitreichenden Folgen f{\"u}r die Gesundheit adip{\"o}ser Patient*innen einhergeht. In der Pathogenese der adipositas-assoziierten Krebsarten sind dabei ein erh{\"o}hter oxidativer Stress sowie die damit einhergehende Sch{\"a}digung der DNS maßgeblich beteiligt. Im Umkehrschluss wurde in der vorliegenden Arbeit der Einfluss eines durch bariatrische Chirurgie induzierten Gewichtsverlusts auf den oxidativen Stress und DNS-Schaden in adip{\"o}sen Patient*innen anhand von Blutproben pr{\"a}operativ sowie 6 und 12 Monate postoperativ untersucht. In einer Subpopulation der Patient*innen konnte eine tendenzielle Verringerung des DNS-Schadens anhand des Comet-Assays in peripheren Lymphozyten beobachtet werden. Im Hinblick auf den oxidativen Stress wurde im Plasma die Eisenreduktionsf{\"a}higkeit als Maß f{\"u}r die antioxidative Kapazit{\"a}t sowie Malondialdehyd als Surrogatmarker f{\"u}r das Ausmaß an Lipidperoxidation bestimmt. Weiterhin wurde in Erythrozyten das Gesamtglutathion und das oxidierte Glutathion bestimmt. Die oxidativen Stressparameter zeigten insgesamt nach einer initialen Zunahme im oxidativen Stress 6 Monate postoperativ eine r{\"u}ckl{\"a}ufige Tendenz im oxidativen Stress am Studienende. Somit geben die Beobachtungen dieser Arbeit Anlass zur Hoffnung, dass adip{\"o}se Patient*innen durch einen bariatrisch induzierten Gewichtsverlust von einer Verringerung des Krebsrisikos profitieren k{\"o}nnten.},
  subject      = {Magenchirurgie},
  language  = {de}
}
@article{BauerMallyLiedtke2021,
  author    = {Bauer, Benedikt and Mally, Angela and Liedtke, Daniel},
  title     = {Zebrafish embryos and larvae as alternative animal models for toxicity testing},
  series = {International Journal of Molecular Sciences},
  volume    = {22},
  journal   = {International Journal of Molecular Sciences},
  number    = {24},
  issn      = {1422-0067},
  doi       = {10.3390/ijms222413417},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-284225},
  year      = {2021},
  abstract  = {Prerequisite to any biological laboratory assay employing living animals is consideration about its necessity, feasibility, ethics and the potential harm caused during an experiment. The imperative of these thoughts has led to the formulation of the 3R-principle, which today is a pivotal scientific standard of animal experimentation worldwide. The rising amount of laboratory investigations utilizing living animals throughout the last decades, either for regulatory concerns or for basic science, demands the development of alternative methods in accordance with 3R to help reduce experiments in mammals. This demand has resulted in investigation of additional vertebrate species displaying favourable biological properties. One prominent species among these is the zebrafish (Danio rerio), as these small laboratory ray-finned fish are well established in science today and feature outstanding biological characteristics. In this review, we highlight the advantages and general prerequisites of zebrafish embryos and larvae before free-feeding stages for toxicological testing, with a particular focus on cardio-, neuro, hepato- and nephrotoxicity. Furthermore, we discuss toxicokinetics, current advances in utilizing zebrafish for organ toxicity testing and highlight how advanced laboratory methods (such as automation, advanced imaging and genetic techniques) can refine future toxicological studies in this species.},
  language  = {en}
}
@article{RietjensDussortGuentheretal.2018,
  author    = {Rietjens, Ivonne M. C. M. and Dussort, P. and G{\"u}nther, Helmut and Hanlon, Paul and Honda, Hiroshi and Mally, Angela and O'Hagan, Sue and Scholz, Gabriele and Seidel, Albrecht and Swenberg, James and Teeguarden, Justin and Eisenbrand, Gerhard},
  title     = {Exposure assessment of process-related contaminants in food by biomarker monitoring},
  series = {Archives of Toxicology},
  volume    = {92},
  journal   = {Archives of Toxicology},
  number    = {1},
  doi       = {10.1007/s00204-017-2143-2},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-226268},
  pages     = {15-40},
  year      = {2018},
  abstract  = {Exposure assessment is a fundamental part of the risk assessment paradigm, but can often present a number of challenges and uncertainties. This is especially the case for process contaminants formed during the processing, e.g. heating of food, since they are in part highly reactive and/or volatile, thus making exposure assessment by analysing contents in food unreliable. New approaches are therefore required to accurately assess consumer exposure and thus better inform the risk assessment. Such novel approaches may include the use of biomarkers, physiologically based kinetic (PBK) modelling-facilitated reverse dosimetry, and/or duplicate diet studies. This review focuses on the state of the art with respect to the use of biomarkers of exposure for the process contaminants acrylamide, 3-MCPD esters, glycidyl esters, furan and acrolein. From the overview presented, it becomes clear that the field of assessing human exposure to process-related contaminants in food by biomarker monitoring is promising and strongly developing. The current state of the art as well as the existing data gaps and challenges for the future were defined. They include (1) using PBK modelling and duplicate diet studies to establish, preferably in humans, correlations between external exposure and biomarkers; (2) elucidation of the possible endogenous formation of the process-related contaminants and the resulting biomarker levels; (3) the influence of inter-individual variations and how to include that in the biomarker-based exposure predictions; (4) the correction for confounding factors; (5) the value of the different biomarkers in relation to exposure scenario's and risk assessment, and (6) the possibilities of novel methodologies. In spite of these challenges it can be concluded that biomarker-based exposure assessment provides a unique opportunity to more accurately assess consumer exposure to process-related contaminants in food and thus to better inform risk assessment.},
  language  = {en}
}
@article{SalingerHuLiuetal.2018,
  author    = {Salinger, Tim and Hu, Kai and Liu, Dan and Taleh, Scharoch and Herrmann, Sebastian and Oder, Daniel and Gensler, Daniel and M{\"u}ntze, Jonas and Ertl, Georg and Lorenz, Kristina and Frantz, Stefan and Weidemann, Frank and Nordbeck, Peter},
  title     = {Association between Comorbidities and Progression of Transvalvular Pressure Gradients in Patients with Moderate and Severe Aortic Valve Stenosis},
  series = {Cardiology Research and Practice},
  journal   = {Cardiology Research and Practice},
  doi       = {10.1155/2018/3713897},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-227291},
  pages     = {3713897, 1-7},
  year      = {2018},
  abstract  = {Background. Fast progression of the transaortic mean gradient (P-mean) is relevant for clinical decision making of valve replacement in patients with moderate and severe aortic stenosis (AS) patients. However, there is currently little knowledge regarding the determinants affecting progression of transvalvular gradient in AS patients. Methods. This monocentric retrospective study included consecutive patients presenting with at least two transthoracic echocardiography examinations covering a time interval of one year or more between April 2006 and February 2016 and diagnosed as moderate or severe aortic stenosis at the final echocardiographic examination. Laboratory parameters, medication, and prevalence of eight known cardiac comorbidities and risk factors (hypertension, diabetes, coronary heart disease, peripheral artery occlusive disease, cerebrovascular disease, renal dysfunction, body mass index >= 30 Kg/m(2), and history of smoking) were analyzed. Patients were divided into slow (P-mean < 5 mmHg/year) or fast (P-mean >= 5 mmHg/year) progression groups. Results. A total of 402 patients (mean age 78 +/- 9.4 years, 58\% males) were included in the study. Mean follow-up duration was 3.4 +/- 1.9 years. The average number of cardiac comorbidities and risk factors was 3.1 +/- 1.6. Average number of cardiac comorbidities and risk factors was higher in patients in slow progression group than in fast progression group (3.3 +/- 1.5 vs 2.9 +/- 1.7; P = 0.036). Patients in slow progression group had more often coronary heart disease (49.2\% vs 33.6\%; P = 0.003) compared to patients in fast progression group. LDL-cholesterol values were lower in the slow progression group (100 +/- 32.6 mg/dl vs 110.8 +/- 36.6 mg/dl; P = 0.005). Conclusion. These findings suggest that disease progression of aortic valve stenosis is faster in patients with fewer cardiac comorbidities and risk factors, especially if they do not have coronary heart disease. Further prospective studies are warranted to investigate the outcome of patients with slow versus fast progression of transvalvular gradient with regards to comorbidities and risk factors.},
  language  = {en}
}
@article{WeigandRonchiRizkRabinetal.2017,
  author    = {Weigand, Isabel and Ronchi, Cristina L. and Rizk-Rabin, Marthe and Dalmazi, Guido Di and Wild, Vanessa and Bathon, Kerstin and Rubin, Beatrice and Calebiro, Davide and Beuschlein, Felix and Bertherat, J{\´e}r{\^o}me and Fassnacht, Martin and Sbiera, Silviu},
  title     = {Differential expression of the protein kinase A subunits in normal adrenal glands and adrenocortical adenomas},
  series = {Scientific Reports},
  volume    = {7},
  journal   = {Scientific Reports},
  number    = {49},
  doi       = {10.1038/s41598-017-00125-8},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-157952},
  year      = {2017},
  abstract  = {Somatic mutations in protein kinase A catalytic α subunit (PRKACA) were found to be causative for 30-40\% of cortisol-producing adenomas (CPA) of the adrenal gland, rendering PKA signalling constitutively active. In its resting state, PKA is a stable and inactive heterotetramer, consisting of two catalytic and two regulatory subunits with the latter inhibiting PKA activity. The human genome encodes three different PKA catalytic subunits and four different regulatory subunits that are preferentially expressed in different organs. In normal adrenal glands all regulatory subunits are expressed, while CPA exhibit reduced protein levels of the regulatory subunit IIβ. In this study, we linked for the first time the loss of RIIβ protein levels to the PRKACA mutation status and found the down-regulation of RIIβ to arise post-transcriptionally. We further found the PKA subunit expression pattern of different tumours is also present in the zones of the normal adrenal cortex and demonstrate that the different PKA subunits have a differential expression pattern in each zone of the normal adrenal gland, indicating potential specific roles of these subunits in the regulation of different hormones secretion.},
  language  = {en}
}
@phdthesis{BathePeters2022,
  author    = {Bathe-Peters, Marc},
  title     = {Spectroscopic approaches for the localization and dynamics of β\(_1\)- and β\(_2\)-adrenergic receptors in cardiomyocytes},
  doi       = {10.25972/OPUS-25812},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-258126},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2022},
  abstract  = {In the heart the β\(_1\)-adrenergic receptor (AR) and the β\(_2\)-AR, two prototypical G protein-coupled receptors (GPCRs), are both activated by the same hormones, namely adrenaline and noradrenaline. Both receptors couple to stimulatory G\(_s\) proteins, mediate an increase in cyclic adenosine monophosphate (cAMP) and influence the contractility and frequency of the heart upon stimulation. However, activation of the β\(_1\)-AR, not the β\(_2\)-AR, lead to other additional effects, such as changes in gene transcription resulting in cardiac hypertrophy, leading to speculations on how distinct effects can arise from receptors coupled to the same downstream signaling pathway. In this thesis the question of whether this distinct behavior may originate from a differential localization of these two receptors in adult cardiomyocytes is addressed. Therefore, fluorescence spectroscopy tools are developed and implemented in order to elucidate the presence and dynamics of these endogenous receptors at the outer plasma membrane as well as on the T-tubular network of intact adult cardiomyocytes. This allows the visualization of confined localization and diffusion of the β\(_2\)-AR to the T-tubular network at endogenous expression. In contrast, the β\(_1\)-AR is found diffusing at both the outer plasma membrane and the T-tubules. Upon overexpression of the β\(_2\)-AR in adult transgenic cardiomyocytes, the receptors experience a loss of this compartmentalization and are also found at the cell surface. These data suggest that distinct signaling and functional effects can be controlled by specific cell surface targeting of the receptor subtypes. The tools at the basis of this thesis work are a fluorescent adrenergic antagonist in combination of fluorescence fluctuation spectroscopy to monitor the localization and dynamics of the lowly expressed adrenergic receptors. Along the way to optimizing these approaches, I worked on combining widefield and confocal imaging in one setup, as well as implementing a stable autofocus mechanism using electrically tunable lenses.},
  subject      = {G-Protein gekoppelte Rezeptoren},
  language  = {en}
}
@article{ChengOthmanStopperetal.2017,
  author    = {Cheng, Cheng and Othman, Eman M. and Stopper, Helga and Edrada-Ebel, RuAngelie and Hentschel, Ute and Abdelmohsen, Usama Ramadan},
  title     = {Isolation of petrocidin A, a new cytotoxic cyclic dipeptide from the marine sponge-derived bacterium \(Streptomyces\) sp. SBT348},
  series = {Marine Drugs},
  volume    = {15},
  journal   = {Marine Drugs},
  number    = {12},
  doi       = {10.3390/md15120383},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-172644},
  year      = {2017},
  abstract  = {A new cyclic dipeptide, petrocidin A (\(\textbf{1}\)), along with three known compounds—2,3-dihydroxybenzoic acid (\(\textbf{2}\)), 2,3-dihydroxybenzamide (\(\textbf{3}\)), and maltol (\(\textbf{4}\))—were isolated from the solid culture of \(Streptomyces\) sp. SBT348. The strain \(Streptomyces\) sp. SBT348 had been prioritized in a strain collection of 64 sponge-associated actinomycetes based on its distinct metabolomic profile using liquid chromatography/high-resolution mass spectrometry (LC-HRMS) and nuclear magnetic resonance (NMR). The absolute configuration of all α-amino acids was determined by HPLC analysis after derivatization with Marfey's reagent and comparison with commercially available reference amino acids. Structure elucidation was pursued in the presented study by mass spectrometry and NMR spectral data. Petrocidin A (\(\textbf{1}\)) and 2,3-dihydroxybenzamide (\(\textbf{3}\)) exhibited significant cytotoxicity towards the human promyelocytic HL-60 and the human colon adenocarcinoma HT-29 cell lines. These results demonstrated the potential of sponge-associated actinomycetes for the discovery of novel and pharmacologically active natural products.},
  language  = {en}
}
@article{SedaghatHamedaniRebsKayvanpouretal.2022,
  author    = {Sedaghat-Hamedani, Farbod and Rebs, Sabine and Kayvanpour, Elham and Zhu, Chenchen and Amr, Ali and M{\"u}ller, Marion and Haas, Jan and Wu, Jingyan and Steinmetz, Lars M. and Ehlermann, Philipp and Streckfuss-B{\"o}meke, Katrin and Frey, Norbert and Meder, Benjamin},
  title     = {Genotype complements the phenotype: identification of the pathogenicity of an LMNA splice variant by nanopore long-read sequencing in a large DCM family},
  series = {International Journal of Molecular Sciences},
  volume    = {23},
  journal   = {International Journal of Molecular Sciences},
  number    = {20},
  issn      = {1422-0067},
  doi       = {10.3390/ijms232012230},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-290415},
  year      = {2022},
  abstract  = {Dilated cardiomyopathy (DCM) is a common cause of heart failure (HF) and is of familial origin in 20-40\% of cases. Genetic testing by next-generation sequencing (NGS) has yielded a definite diagnosis in many cases; however, some remain elusive. In this study, we used a combination of NGS, human-induced pluripotent-stem-cell-derived cardiomyocytes (iPSC-CMs) and nanopore long-read sequencing to identify the causal variant in a multi-generational pedigree of DCM. A four-generation family with familial DCM was investigated. Next-generation sequencing (NGS) was performed on 22 family members. Skin biopsies from two affected family members were used to generate iPSCs, which were then differentiated into iPSC-CMs. Short-read RNA sequencing was used for the evaluation of the target gene expression, and long-read RNA nanopore sequencing was used to evaluate the relevance of the splice variants. The pedigree suggested a highly penetrant, autosomal dominant mode of inheritance. The phenotype of the family was suggestive of laminopathy, but previous genetic testing using both Sanger and panel sequencing only yielded conflicting evidence for LMNA p.R644C (rs142000963), which was not fully segregated. By re-sequencing four additional affected family members, further non-coding LMNA variants could be detected: rs149339264, rs199686967, rs201379016, and rs794728589. To explore the roles of these variants, iPSC-CMs were generated. RNA sequencing showed the LMNA expression levels to be significantly lower in the iPSC-CMs of the LMNA variant carriers. We demonstrated a dysregulated sarcomeric structure and altered calcium homeostasis in the iPSC-CMs of the LMNA variant carriers. Using targeted nanopore long-read sequencing, we revealed the biological significance of the variant c.356+1G>A, which generates a novel 5′ splice site in exon 1 of the cardiac isomer of LMNA, causing a nonsense mRNA product with almost complete RNA decay and haploinsufficiency. Using novel molecular analysis and nanopore technology, we demonstrated the pathogenesis of the rs794728589 (c.356+1G>A) splice variant in LMNA. This study highlights the importance of precise diagnostics in the clinical management and workup of cardiomyopathies.},
  language  = {en}
}
@phdthesis{Nemec2023,
  author    = {Nemec, Katarina},
  title     = {Modulation of parathyroid hormone 1 receptor (PTH1R) signaling by receptor activity-modifying proteins (RAMPs)},
  doi       = {10.25972/OPUS-28858},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-288588},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {The receptor activity-modifying proteins (RAMPs) are ubiquitously expressed membrane proteins that interact with several G protein-coupled receptors (GPCRs), the largest and pharmacologically most important family of cell surface receptors. RAMPs can regulate GPCR function in terms of ligand-binding, G-protein coupling, downstream signaling, trafficking, and recycling. The integrity of their interactions translates to many physiological functions or pathological conditions. Regardless of numerous reports on its essential importance for cell biology and pivotal role in (patho-)physiology, the molecular mechanism of how RAMPs modulate GPCR activation remained largely elusive. This work presents new insights that add to the common understanding of the allosteric regulation of receptor activation and will help interpret how accessory proteins - RAMPs - modulate activation dynamics and how this affects the fundamental aspects of cellular signaling. Using a prototypical class B GPCR, the parathyroid hormone 1 receptor (PTH1R) in the form of advanced genetically encoded optical biosensors, I examined RAMP's impact on the PTH1R activation and signaling in intact cells. A panel of single-cell FRET and confocal microscopy experiments as well canonical and non-canonical functional assays were performed to get a holistic picture of the signaling initiation and transduction of that clinically and therapeutically relevant GPCR. Finally, structural modeling was performed to add molecular mechanistic details to that novel art of modulation. I describe here that RAMP2 acts as a specific allosteric modulator of PTH1R, shifting PTH1R to a unique pre-activated state that permits faster activation in a ligand-specific manner. Moreover, RAMP2 modulates PTH1R downstream signaling in an agonist-dependent manner, most notably increasing the PTH-mediated Gi3 signaling sensitivity and kinetics of cAMP accumulation. Additionally, RAMP2 increases PTH- and PTHrP-triggered β-arrestin2 recruitment to PTH1R and modulates cytosolic ERK1/2 phosphorylation. Structural homology modeling shows that structural motifs governing GPCR-RAMP interaction originate in allosteric hotspots and rationalize functional modulation. Moreover, to interpret the broader role of RAMP's modulation in GPCRs pharmacology, different fluorescent tools to investigate RAMP's spatial organization were developed, and novel conformational biosensors for class B GPCRs were engineered. Lastly, a high throughput assay is proposed and prototyped to expand the repertoire of RAMPs or other membrane protein interactors. These data uncover the critical role of RAMPs in GPCR activation and signaling and set up a novel platform for studying GPCR modulation. Furthermore, these insights may provide a new venue for precise modulation of GPCR function and advanced drug design.},
  subject      = {G-Protein gekoppelter Rezeptor},
  language  = {en}
}
@article{HartmannKnierimMaureretal.2023,
  author    = {Hartmann, Nico and Knierim, Maria and Maurer, Wiebke and Dybkova, Nataliya and Hasenfuß, Gerd and Sossalla, Samuel and Streckfuss-B{\"o}meke, Katrin},
  title     = {Molecular and functional relevance of Na\(_V\)1.8-induced atrial arrhythmogenic triggers in a human SCN10A knock-out stem cell model},
  series = {International Journal of Molecular Sciences},
  volume    = {24},
  journal   = {International Journal of Molecular Sciences},
  number    = {12},
  issn      = {1422-0067},
  doi       = {10.3390/ijms241210189},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-362708},
  year      = {2023},
  abstract  = {In heart failure and atrial fibrillation, a persistent Na\(^+\) current (I\(_{NaL}\)) exerts detrimental effects on cellular electrophysiology and can induce arrhythmias. We have recently shown that Na\(_V\)1.8 contributes to arrhythmogenesis by inducing a I\(_{NaL}\). Genome-wide association studies indicate that mutations in the SCN10A gene (Na\(_V\)1.8) are associated with increased risk for arrhythmias, Brugada syndrome, and sudden cardiac death. However, the mediation of these Na\(_V\)1.8-related effects, whether through cardiac ganglia or cardiomyocytes, is still a subject of controversial discussion. We used CRISPR/Cas9 technology to generate homozygous atrial SCN10A-KO-iPSC-CMs. Ruptured-patch whole-cell patch-clamp was used to measure the I\(_{NaL}\) and action potential duration. Ca\(^{2+}\) measurements (Fluo 4-AM) were performed to analyze proarrhythmogenic diastolic SR Ca\(^{2+}\) leak. The I\(_{NaL}\) was significantly reduced in atrial SCN10A KO CMs as well as after specific pharmacological inhibition of Na\(_V\)1.8. No effects on atrial APD\(_{90}\) were detected in any groups. Both SCN10A KO and specific blockers of Na\(_V\)1.8 led to decreased Ca\(^{2+}\) spark frequency and a significant reduction of arrhythmogenic Ca\(^{2+}\) waves. Our experiments demonstrate that Na\(_V\)1.8 contributes to I\(_{NaL}\) formation in human atrial CMs and that Na\(_V\)1.8 inhibition modulates proarrhythmogenic triggers in human atrial CMs and therefore Na\(_V\)1.8 could be a new target for antiarrhythmic strategies.},
  language  = {en}
}
@article{LorenzRosner2022,
  author    = {Lorenz, Kristina and Rosner, Marsha Rich},
  title     = {Harnessing RKIP to combat heart disease and cancer},
  series = {Cancers},
  volume    = {14},
  journal   = {Cancers},
  number    = {4},
  issn      = {2072-6694},
  doi       = {10.3390/cancers14040867},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-262185},
  year      = {2022},
  abstract  = {Cancer and heart disease are leading causes of morbidity and mortality worldwide. These diseases have common risk factors, common molecular signaling pathways that are central to their pathogenesis, and even some disease phenotypes that are interdependent. Thus, a detailed understanding of common regulators is critical for the development of new and synergistic therapeutic strategies. The Raf kinase inhibitory protein (RKIP) is a regulator of the cellular kinome that functions to maintain cellular robustness and prevent the progression of diseases including heart disease and cancer. Two of the key signaling pathways controlled by RKIP are the β-adrenergic receptor (βAR) signaling to protein kinase A (PKA), particularly in the heart, and the MAP kinase cascade Raf/MEK/ERK1/2 that regulates multiple diseases. The goal of this review is to discuss how we can leverage RKIP to suppress cancer without incurring deleterious effects on the heart. Specifically, we discuss: (1) How RKIP functions to either suppress or activate βAR (PKA) and ERK1/2 signaling; (2) How we can prevent cancer-promoting kinase signaling while at the same time avoiding cardiotoxicity.},
  language  = {en}
}
@article{ObidiegwuLyonsChilaka2020,
  author    = {Obidiegwu, Jude E. and Lyons, Jessica B. and Chilaka, Cynthia A.},
  title     = {The Dioscorea genus (yam) — an appraisal of nutritional and therapeutic potentials},
  series = {Foods},
  volume    = {9},
  journal   = {Foods},
  number    = {9},
  issn      = {2304-8158},
  doi       = {10.3390/foods9091304},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-213102},
  year      = {2020},
  abstract  = {The quest for a food secure and safe world has led to continuous effort toward improvements of global food and health systems. While the developed countries seem to have these systems stabilized, some parts of the world still face enormous challenges. Yam (Dioscorea species) is an orphan crop, widely distributed globally; and has contributed enormously to food security especially in sub-Saharan Africa because of its role in providing nutritional benefits and income. Additionally, yam has non-nutritional components called bioactive compounds, which offer numerous health benefits ranging from prevention to treatment of degenerative diseases. Pharmaceutical application of diosgenin and dioscorin, among other compounds isolated from yam, has shown more prospects recently. Despite the benefits embedded in yam, reports on the nutritional and therapeutic potentials of yam have been fragmented and the diversity within the genus has led to much confusion. An overview of the nutritional and health importance of yam will harness the crop to meet its potential towards combating hunger and malnutrition, while improving global health. This review makes a conscious attempt to provide an overview regarding the nutritional, bioactive compositions and therapeutic potentials of yam diversity. Insights on how to increase its utilization for a greater impact are elucidated.},
  language  = {en}
}
@article{BalasubramanianOthmanKampiketal.2017,
  author    = {Balasubramanian, Srikkanth and Othman, Eman M. and Kampik, Daniel and Stopper, Helga and Hentschel, Ute and Ziebuhr, Wilma and Oelschlaeger, Tobias A. and Abdelmohsen, Usama R.},
  title     = {Marine sponge-derived Streptomyces sp SBT343 extract inhibits staphylococcal biofilm formation},
  series = {Frontiers in Microbiology},
  volume    = {8},
  journal   = {Frontiers in Microbiology},
  doi       = {10.3389/fmicb.2017.00236},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-171844},
  year      = {2017},
  abstract  = {Staphylococcus epidermidis and Staphylococcus aureus are opportunistic pathogens that cause nosocomial and chronic biofilm-associated infections. Indwelling medical devices and contact lenses are ideal ecological niches for formation of staphylococcal biofilms. Bacteria within biofilms are known to display reduced susceptibilities to antimicrobials and are protected from the host immune system. High rates of acquired antibiotic resistances in staphylococci and other biofilm-forming bacteria further hamper treatment options and highlight the need for new anti-biofilm strategies. Here, we aimed to evaluate the potential of marine sponge-derived actinomycetes in inhibiting biofilm formation of several strains of S. epidermidis, S. aureus, and Pseudomonas aeruginosa. Results from in vitro biofilm-formation assays, as well as scanning electron and confocal microscopy, revealed that an organic extract derived from the marine sponge-associated bacterium Streptomyces sp. SBT343 significantly inhibited staphylococcal biofilm formation on polystyrene, glass and contact lens surfaces, without affecting bacterial growth. The extract also displayed similar antagonistic effects towards the biofilm formation of other S. epidermidis and S. aureus strains tested but had no inhibitory effects towards Pseudomonas biofilms. Interestingly the extract, at lower effective concentrations, did not exhibit cytotoxic effects on mouse fibroblast, macrophage and human corneal epithelial cell lines. Chemical analysis by High Resolution Fourier Transform Mass Spectrometry (HRMS) of the Streptomyces sp. SBT343 extract proportion revealed its chemical richness and complexity. Preliminary physico-chemical characterization of the extract highlighted the heat-stable and non-proteinaceous nature of the active component(s). The combined data suggest that the Streptomyces sp. SBT343 extract selectively inhibits staphylococcal biofilm formation without interfering with bacterial cell viability. Due to absence of cell toxicity, the extract might represent a good starting material to develop a future remedy to block staphylococcal biofilm formation on contact lenses and thereby to prevent intractable contact lens-mediated ocular infections.},
  language  = {en}
}
@phdthesis{Raab2018,
  author    = {Raab, Annette},
  title     = {The role of Rgs2 in animal models of affective disorders},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-152550},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {Anxiety and depressive disorders result from a complex interplay of genetic and environmental factors and are common mutual comorbidities. On the level of cellular signaling, regulator of G protein signaling 2 (Rgs2) has been implicated in human and rodent anxiety as well as rodent depression. Rgs2 negatively regulates G protein-coupled receptor (GPCR) signaling by acting as a GTPase accelerating protein towards the Gα subunit. The present study investigates, whether mice with a homozygous Rgs2 deletion (Rgs2-/-) show behavioral alterations as well as an increased susceptibility to stressful life events related to human anxiety and depressive disorders and tries to elucidate molecular underlying's of these changes. To this end, Rgs2-/- mice were characterized in an aversive-associative learning paradigm to evaluate learned fear as a model for the etiology of human anxiety disorders. Spatial learning and reward motivated spatial learning were evaluated to control for learning in non-aversive paradigms. Rgs2 deletion enhanced learning in all three paradigms, rendering increased learning upon deletion of Rgs2 not specific for aversive learning. These data support reports indicating increased long-term potentiation in Rgs2-/- mice and may predict treatment response to conditioning based behavior therapy in patients with polymorphisms associated with reduced RGS2 expression. Previous reports of increased innate anxiety were corroborated in three tests based on the approach-avoidance conflict. Interestingly, Rgs2-/- mice showed novelty-induced hypo-locomotion suggesting neophobia, which may translate to the clinical picture of agoraphobia in humans and reduced RGS2 expression in humans was associated with a higher incidence of panic disorder with agoraphobia. Depression-like behavior was more distinctive in female Rgs2-/- mice. Stress resilience, tested in an acute and a chronic stress paradigm, was also more distinctive in female Rgs2-/- mice, suggesting Rgs2 to contribute to sex specific effects of anxiety disorders and depression. Rgs2 deletion was associated with GPCR expression changes of the adrenergic, serotonergic, dopaminergic and neuropeptide Y systems in the brain and heart as well as reduced monoaminergic neurotransmitter levels. Furthermore, the expression of two stress-related microRNAs was increased upon Rgs2 deletion. The aversive-associative learning paradigm induced a dynamic Rgs2 expression change. The observed molecular changes may contribute to the anxious and depressed phenotype as well as promote altered stress reactivity, while reflecting an alter basal stress level and a disrupted sympathetic tone. Dynamic Rgs2 expression may mediate changes in GPCR signaling duration during memory formation. Taken together, Rgs2 deletion promotes increased anxiety-like and depression-like behavior, altered stress reactivity as well as increased cognitive function.},
  subject      = {Angst},
  language  = {en}
}
@phdthesis{Wilde2019,
  author    = {Wilde, Sabrina},
  title     = {Einsatz von mechanistischen Biomarkern zur Charakterisierung und Bewertung von \(in\) \(vitro\) Genotoxinen},
  doi       = {10.25972/OPUS-18278},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-182782},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {Die verf{\"u}gbaren in vitro Genotoxizit{\"a}tstests weisen hinsichtlich ihrer Spezifit{\"a}t und ihres Informationsgehalts zum vorliegenden Wirkmechanismus (Mode of Action, MoA) Einschr{\"a}nkungen auf. Um diese M{\"a}ngel zu {\"u}berwinden, wurden in dieser Arbeit zwei Ziele verfolgt, die zu der Entwicklung und Etablierung neuer in vitro Methoden zur Pr{\"u}fung auf Genotoxizit{\"a}t in der Arzneimittelentwicklung beitragen. 1. Etablierung und Bewertung einer neuen in vitro Genotoxizit{\"a}tsmethode (MultiFlow Methode) Die MultiFlow Methode basiert auf DNA-schadensassoziierten Proteinantworten von γH2AX (DNA-Doppelstrangbr{\"u}che), phosphorylierten H3 (S10) (mitotische Zellen), nukle{\"a}ren Protein p53 (Genotoxizit{\"a}t) und cleaved PARP1 (Apoptose) in TK6-Zellen. Insgesamt wurden 31 Modellsubstanzen mit dem MultiFlow Assay und erg{\"a}nzend mit dem etablierten Mikrokerntest (MicroFlow MNT), auf ihre F{\"a}higkeit verschiedene MoA-Gruppen (Aneugene/Klastogene/Nicht-Genotoxine) zu differenzieren, untersucht. Die Performance der „neuen" gegen{\"u}ber der „alten" Methode f{\"u}hrte zu einer verbesserten Sensitivit{\"a}t von 95\% gegen{\"u}ber 90\%, Spezifit{\"a}t von 90\% gegen{\"u}ber 72\% und einer MoA-Klassifizierungsrate von 85\% gegen{\"u}ber 45\% (Aneugen vs. Klastogen). 2. Identifizierung mechanistischer Biomarker zur Klassifizierung genotoxischer Substanzen Die Analyse 67 ausgew{\"a}hlter DNA-schadensassoziierter Gene in der QuantiGene Plex Methode zeigte, dass mehrere Gene gleichzeitig zur MoA-Klassifizierung beitragen k{\"o}nnen. Die Kombination der h{\"o}chstrangierten Marker BIK, KIF20A, TP53I3, DDB2 und OGG1 erm{\"o}glichte die beste Identifizierungsrate der Modellsubstanzen. Das synergetische Modell kategorisierte 16 von 16 Substanzen korrekt in Aneugene, Klastogene und Nicht-Genotoxine. Unter Verwendung der Leave-One-Out-Kreuzvalidierung wurde das Modell evaluiert und erreichte eine Sensitivit{\"a}t, Spezifit{\"a}t und Pr{\"a}diktivit{\"a}t von 86\%, 83\% und 85\%. Ergebnisse der traditionellen qPCR Methode zeigten, dass Genotoxizit{\"a}t mit TP53I3, Klastogenit{\"a}t mit ATR und RAD17 und oxidativer Stress mit NFE2L2 detektiert werden kann. Durch die Untersuchungen von posttranslationalen Modifikationen unter Verwendung der High-Content-Imaging-Technologie wurden mechanistische Assoziationen f{\"u}r BubR1 (S670) und pH3 (S28) mit Aneugenit{\"a}t, 53BP1 (S1778) und FANCD2 (S1404) mit Klastogenit{\"a}t, p53 (K373) mit Genotoxizit{\"a}t und Nrf2 (S40) mit oxidativem Stress identifiziert. Diese Arbeit zeigt, dass (Geno)toxine unterschiedliche Gen- und Proteinver{\"a}nderungen in TK6-Zellen induzieren, die zur Erfassung mechanistischer Aktivit{\"a}ten und Einteilung (geno)toxischer MoA-Gruppen (Aneugen/Klastogen/ Reaktive Sauerstoffspezies) eingesetzt werden k{\"o}nnen und daher eine bessere Risikobewertung von Wirkstoffkandidaten erm{\"o}glichen.},
  subject      = {Genotoxizit{\"a}t},
  language  = {de}
}
@article{VazquezRodriguezVilarKachleretal.2020,
  author    = {Vazquez-Rodriguez, Saleta and Vilar, Santiago and Kachler, Sonja and Klotz, Karl-Norbert and Uriarte, Eugenio and Borges, Fernanda and Matos, Maria Jo{\~a}o},
  title     = {Adenosine receptor ligands: coumarin-chalcone hybrids as modulating agents on the activity of hARs},
  series = {Molecules},
  volume    = {25},
  journal   = {Molecules},
  number    = {18},
  issn      = {1420-3049},
  doi       = {10.3390/molecules25184306},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-213165},
  year      = {2020},
  abstract  = {Adenosine receptors (ARs) play an important role in neurological and psychiatric disorders such as Alzheimer's disease, Parkinson's disease, epilepsy and schizophrenia. The different subtypes of ARs and the knowledge on their densities and status are important for understanding the mechanisms underlying the pathogenesis of diseases and for developing new therapeutics. Looking for new scaffolds for selective AR ligands, coumarin-chalcone hybrids were synthesized (compounds 1-8) and screened in radioligand binding (hA\(_1\), hA\(_{2A}\) and hA\(_3\)) and adenylyl cyclase (hA\(_{2B}\)) assays in order to evaluate their affinity for the four human AR subtypes (hARs). Coumarin-chalcone hybrid has been established as a new scaffold suitable for the development of potent and selective ligands for hA\(_1\) or hA\(_3\) subtypes. In general, hydroxy-substituted hybrids showed some affinity for the hA\(_1\), while the methoxy counterparts were selective for the hA\(_3\). The most potent hA\(_1\) ligand was compound 7 (K\(_i\) = 17.7 µM), whereas compound 4 was the most potent ligand for hA\(_3\) (K\(_i\) = 2.49 µM). In addition, docking studies with hA\(_1\) and hA\(_3\) homology models were established to analyze the structure-function relationships. Results showed that the different residues located on the protein binding pocket could play an important role in ligand selectivity.},
  language  = {en}
}
@phdthesis{Anton2021,
  author    = {Anton, Selma},
  title     = {Characterization of cAMP nanodomains surrounding the human Glucagon-like peptide 1 receptor using FRET-based reporters},
  doi       = {10.25972/OPUS-19069},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-190695},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Cyclic adenosine monophosphate (cAMP), the ubiquitous second messenger produced upon stimulation of GPCRs which couple to the stimulatory GS protein, orchestrates an array of physiological processes including cardiac function, neuronal plasticity, immune responses, cellular proliferation and apoptosis. By interacting with various effector proteins, among others protein kinase A (PKA) and exchange proteins directly activated by cAMP (Epac), it triggers signaling cascades for the cellular response. Although the functional outcomes of GSPCR-activation are very diverse depending on the extracellular stimulus, they are all mediated exclusively by this single second messenger. Thus, the question arises how specificity in such responses may be attained. A hypothesis to explain signaling specificity is that cellular signaling architecture, and thus precise operation of cAMP in space and time would appear to be essential to achieve signaling specificity. Compartments with elevated cAMP levels would allow specific signal relay from receptors to effectors within a micro- or nanometer range, setting the molecular basis for signaling specificity. Although the paradigm of signaling compartmentation gains continuous recognition and is thoroughly being investigated, the molecular composition of such compartments and how they are maintained remains to be elucidated. In addition, such compartments would require very restricted diffusion of cAMP, but all direct measurements have indicated that it can diffuse in cells almost freely. In this work, we present the identification and characterize of a cAMP signaling compartment at a GSPCR. We created a F{\"o}rster resonance energy transfer (FRET)-based receptor-sensor conjugate, allowing us to study cAMP dynamics in direct vicinity of the human glucagone-like peptide 1 receptor (hGLP1R). Additional targeting of analogous sensors to the plasma membrane and the cytosol enables assessment of cAMP dynamics in different subcellular regions. We compare both basal and stimulated cAMP levels and study cAMP crosstalk of different receptors. With the design of novel receptor nanorulers up to 60nm in length, which allow mapping cAMP levels in nanometer distance from the hGLP1R, we identify a cAMP nanodomain surrounding it. Further, we show that phosphodiesterases (PDEs), the only enzymes known to degrade cAMP, are decisive in constraining cAMP diffusion into the cytosol thereby maintaining a cAMP gradient. Following the discovery of this nanodomain, we sought to investigate whether downstream effectors such as PKA are present and active within the domain, additionally studying the role of A-kinase anchoring proteins (AKAPs) in targeting PKA to the receptor compartment. We demonstrate that GLP1-produced cAMP signals translate into local nanodomain-restricted PKA phosphorylation and determine that AKAP-tethering is essential for nanodomain PKA. Taken together, our results provide evidence for the existence of a dynamic, receptor associated cAMP nanodomain and give prospect for which key proteins are likely to be involved in its formation. These conditions would allow cAMP to exert its function in a spatially and temporally restricted manner, setting the basis for a cell to achieve signaling specificity. Understanding the molecular mechanism of cAMP signaling would allow modulation and thus regulation of GPCR signaling, taking advantage of it for pharmacological treatment.},
  language  = {en}
}
@article{SegererHadamekZundleretal.2016,
  author    = {Segerer, Gabriela and Hadamek, Kerstin and Zundler, Matthias and Fekete, Agnes and Seifried, Annegrit and Mueller, Martin J. and Koentgen, Frank and Gessler, Manfred and Jeanclos, Elisabeth and Gohla, Antje},
  title     = {An essential developmental function for murine phosphoglycolate phosphatase in safeguarding cell proliferation},
  series = {Scientific Reports},
  volume    = {6},
  journal   = {Scientific Reports},
  doi       = {10.1038/srep35160},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-181094},
  year      = {2016},
  abstract  = {Mammalian phosphoglycolate phosphatase (PGP) is thought to target phosphoglycolate, a 2-deoxyribose fragment derived from the repair of oxidative DNA lesions. However, the physiological role of this activity and the biological function of the DNA damage product phosphoglycolate is unknown. We now show that knockin replacement of murine Pgp with its phosphatase-inactive Pgp\(^{D34N}\) mutant is embryonically lethal due to intrauterine growth arrest and developmental delay in midgestation. PGP inactivation attenuated triosephosphate isomerase activity, increased triglyceride levels at the expense of the cellular phosphatidylcholine content, and inhibited cell proliferation. These effects were prevented under hypoxic conditions or by blocking phosphoglycolate release from damaged DNA. Thus, PGP is essential to sustain cell proliferation in the presence of oxygen. Collectively, our findings reveal a previously unknown mechanism coupling a DNA damage repair product to the control of intermediary metabolism and cell proliferation.},
  language  = {en}
}
@article{ReimannStopperPolaketal.2020,
  author    = {Reimann, Hauke and Stopper, Helga and Polak, Thomas and Lauer, Martin and Herrmann, Martin J. and Deckert, J{\"u}rgen and Hintzsche, Henning},
  title     = {Micronucleus frequency in buccal mucosa cells of patients with neurodegenerative diseases},
  series = {Scientific Reports},
  volume    = {10},
  journal   = {Scientific Reports},
  doi       = {10.1038/s41598-020-78832-y},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-231430},
  year      = {2020},
  abstract  = {Neurodegenerative diseases show an increase in prevalence and incidence, with the most prominent example being Alzheimer's disease. DNA damage has been suggested to play a role in the pathogenesis, but the exact mechanisms remain elusive. We enrolled 425 participants with and without neurodegenerative diseases and analyzed DNA damage in the form of micronuclei in buccal mucosa samples. In addition, other parameters such as binucleated cells, karyolytic cells, and karyorrhectic cells were quantified. No relevant differences in DNA damage and cytotoxicity markers were observed in patients compared to healthy participants. Furthermore, other parameters such as lifestyle factors and diseases were also investigated. Overall, this study could not identify a direct link between changes in buccal cells and neurogenerative diseases, but highlights the influence of lifestyle factors and diseases on the human buccal cytome.},
  language  = {en}
}
@article{WagnerSadekDybkovaetal.2021,
  author    = {Wagner, Michael and Sadek, Mirna S. and Dybkova, Nataliya and Mason, Fleur E. and Klehr, Johann and Firneburg, Rebecca and Cachorro, Eleder and Richter, Kurt and Klapproth, Erik and Kuenzel, Stephan R. and Lorenz, Kristina and Heijman, Jordi and Dobrev, Dobromir and El-Armouche, Ali and Sossalla, Samuel and K{\"a}mmerer, Susanne},
  title     = {Cellular mechanisms of the anti-arrhythmic effect of cardiac PDE2 overexpression},
  series = {International Journal of Molecular Sciences},
  volume    = {22},
  journal   = {International Journal of Molecular Sciences},
  number    = {9},
  issn      = {1422-0067},
  doi       = {10.3390/ijms22094816},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-285888},
  year      = {2021},
  abstract  = {Background: Phosphodiesterases (PDE) critically regulate myocardial cAMP and cGMP levels. PDE2 is stimulated by cGMP to hydrolyze cAMP, mediating a negative crosstalk between both pathways. PDE2 upregulation in heart failure contributes to desensitization to β-adrenergic overstimulation. After isoprenaline (ISO) injections, PDE2 overexpressing mice (PDE2 OE) were protected against ventricular arrhythmia. Here, we investigate the mechanisms underlying the effects of PDE2 OE on susceptibility to arrhythmias. Methods: Cellular arrhythmia, ion currents, and Ca\(^{2+}\)-sparks were assessed in ventricular cardiomyocytes from PDE2 OE and WT littermates. Results: Under basal conditions, action potential (AP) morphology were similar in PDE2 OE and WT. ISO stimulation significantly increased the incidence of afterdepolarizations and spontaneous APs in WT, which was markedly reduced in PDE2 OE. The ISO-induced increase in I\(_{CaL}\) seen in WT was prevented in PDE2 OE. Moreover, the ISO-induced, Epac- and CaMKII-dependent increase in I\(_{NaL}\) and Ca\(^{2+}\)-spark frequency was blunted in PDE2 OE, while the effect of direct Epac activation was similar in both groups. Finally, PDE2 inhibition facilitated arrhythmic events in ex vivo perfused WT hearts after reperfusion injury. Conclusion: Higher PDE2 abundance protects against ISO-induced cardiac arrhythmia by preventing the Epac- and CaMKII-mediated increases of cellular triggers. Thus, activating myocardial PDE2 may represent a novel intracellular anti-arrhythmic therapeutic strategy in HF.},
  language  = {en}
}
@article{SchanbacherBieberReindersetal.2022,
  author    = {Schanbacher, Constanze and Bieber, Michael and Reinders, Yvonne and Cherpokova, Deya and Teichert, Christina and Nieswandt, Bernhard and Sickmann, Albert and Kleinschnitz, Christoph and Langhauser, Friederike and Lorenz, Kristina},
  title     = {ERK1/2 activity is critical for the outcome of ischemic stroke},
  series = {International Journal of Molecular Sciences},
  volume    = {23},
  journal   = {International Journal of Molecular Sciences},
  number    = {2},
  issn      = {1422-0067},
  doi       = {10.3390/ijms23020706},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-283991},
  year      = {2022},
  abstract  = {Ischemic disorders are the leading cause of death worldwide. The extracellular signal-regulated kinases 1 and 2 (ERK1/2) are thought to affect the outcome of ischemic stroke. However, it is under debate whether activation or inhibition of ERK1/2 is beneficial. In this study, we report that the ubiquitous overexpression of wild-type ERK2 in mice (ERK2\(^{wt}\)) is detrimental after transient occlusion of the middle cerebral artery (tMCAO), as it led to a massive increase in infarct volume and neurological deficits by increasing blood-brain barrier (BBB) leakiness, inflammation, and the number of apoptotic neurons. To compare ERK1/2 activation and inhibition side-by-side, we also used mice with ubiquitous overexpression of the Raf-kinase inhibitor protein (RKIP\(^{wt}\)) and its phosphorylation-deficient mutant RKIP\(^{S153A}\), known inhibitors of the ERK1/2 signaling cascade. RKIP\(^{wt}\) and RKIP\(^{S153A}\) attenuated ischemia-induced damages, in particular via anti-inflammatory signaling. Taken together, our data suggest that stimulation of the Raf/MEK/ERK1/2-cascade is severely detrimental and its inhibition is rather protective. Thus, a tight control of the ERK1/2 signaling is essential for the outcome in response to ischemic stroke.},
  language  = {en}
}
@phdthesis{Kauk2018,
  author    = {Kauk, Michael},
  title     = {Investigating the Molecular Mechanism of Receptor Activation at Muscarinic Receptors by Means of Pathway-Specific Dualsteric Ligands and Partial Agonists},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-173729},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2018},
  abstract  = {G protein-coupled receptors (GPCRs) form the biggest receptor family that is encoded in the human genome and represent the most druggable target structure for modern therapeutics respectively future drug development. Belonging to aminergic class A GPCRs muscarinic Acetylcholine receptors (mAChRs) are already now of clinical relevance and are also seen as promising future drug targets for treating neurodegenerative diseases like Alzheimer or Parkinson. The mAChR family consist of five subtypes showing high sequence identity for the endogenous ligand binding region and thus it is challenging until now to selectively activate a single receptor subtype. A well accepted method to study ligand binding, dynamic receptor activation and downstream signaling is the fluorescence resonance energy transfer (FRET) application. Here, there relative distance between two fluorophores in close proximity (<10 nm) can be monitored in a dynamic manner. The perquisite for that is the spectral overlap of the emission spectrum of the first fluorophore with the excitation spectrum of the second fluorophore. By inserting two fluorophores into the molecular receptor structure receptor FRET sensors can serve as a powerful tool to study dynamic receptor pharmacology. Dualsteric Ligands consist of two different pharmacophoric entities and are regarded as a promising ligand design for future drug development. The orthosteric part interacts with high affinity with the endogenous ligand binding region whereas the allosteric part binds to a different receptor region mostly located in the extracellular vestibule. Both moieties are covalently linked. Dualsteric ligands exhibit a dynamic ligand binding. The dualsteric binding position is characterized by a simultaneous binding of the orthosteric and allosteric moiety to the receptor and thus by receptor activation. In the purely allosteric binding position no receptor activation can be monitored. In the present work the first receptor FRET sensor for the muscarinic subtype 1 (M1) was generated and characterized. The M1-I3N-CFP sensor showed an unaltered physiological behavior as well as ligand and concentration dependent responses. The sensor was used to characterize different sets of dualsteric ligands concerning their pharmacological properties like receptor activation. It was shown that the hybrids consisting of the synthetic full agonist iperoxo and the positive allosteric modulator of BQCA type is very promising. Furthermore, it was shown for orthosteric as well as dualsteric ligands that the degree of receptor activation is highly dependent on the length of and the chemical properties of the linker moiety. For dualsteric ligands a bell-shaped activation characteristic was reported for the first time, suggesting that there is an optimal linker length for dualsteric ligands. The gained knowledge about hybrid design was then used to generate and characterize the first photo-switchable dualsteric ligand. The resulting hybrids were characterized with the M1-I3N-CFP sensor and were described as photo-inactivatable and dimmable. In addition to the ligand characterization the ligand application methodology was further developed and improved. Thus, a fragment-based screening approach for dualsteric ligands was reported in this study for the first time. With this approach it is possible to investigate dualsteric ligands in greater detail by applying either single ligand fragments alone or in a mixture of building blocks. These studies revealed the insights that the effect of dualsteric ligands on a GPCR can be rebuild by applying the single building blocks simultaneously. The fragment-based screening provides high potential for the molecular understanding of dualsteric ligands and for future screening approaches. Next, a further development of the standard procedure for measuring FRET by sensitized emission was performed. Under normal conditions single cell FRET is measured on glass coverslips. After coating the coverslips surface with a 20 nm thick gold layer an increased FRET efficiency up to 60 \% could be reported. This finding was validated in different approaches und in different configurations. This FRET enhancement by plasmonic surfaces was until yet unreported in the literature for physiological systems and make FRET for future projects even more powerful.},
  subject      = {G-Protein gekoppelte Rezeptoren},
  language  = {en}
}