@phdthesis{Kodandaraman2021, author = {Kodandaraman, Geema}, title = {Influence of insulin-induced oxidative stress in genotoxicity and disease}, doi = {10.25972/OPUS-24200}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-242005}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2021}, abstract = {Hormones are essential components in the body and their imbalance leads to pathological consequences. T2DM, insulin resistance and obesity are the most commonly occurring lifestyle diseases in the past decade. Also, an increased cancer incidence has been strongly associated with obese and T2DM patients. Therefore, our aim was to study the influence of high insulin levels in accumulating DNA damage in in vitro models and patients, through the induction of oxidative stress. The primary goal of this study was to analyze the genotoxicity induced by the combined action of two endogenous hormones (insulin and adrenaline) with in vitro models, through the induction of micronuclei and to see if they cause an additive increase in genomic damage. This is important for multifactorial diseases having high levels of more than one hormone, such as metabolic syndrome and conditions with multiple pathologies (e.g., T2DM along with high stress levels). Furthermore, the combination of insulin and the pharmacological inhibition of the tumor suppressor gene: PTEN, was to be tested in in vitro models for their genotoxic effect and oxidative stress inducing potential. As the tumor suppressor gene: PTEN is downregulated in PTEN associated syndromes and when presented along with T2DM and insulin resistance, this may increase the potential to accumulate genomic damage. The consequences of insulin action were to be further elucidated by following GFP-expressing cells in live cell-imaging to observe the ability of insulin, to induce micronuclei and replicative stress. Finally, the detrimental potential of high insulin levels in obese patients with hyperinsulinemia and pre-diabetes was to be studied by analyzing markers of oxidative stress and genomic damage. In summary, the intention of this work was to understand the effects of high insulin levels in in vitro and in patients to understand its relevance for the development of genomic instability and thus an elevated cancer risk.}, subject = {Insulin}, language = {en} } @phdthesis{Schihada2021, author = {Schihada, Hannes}, title = {Novel optical methods to monitor G-protein-coupled receptor activation in microtiter plates}, doi = {10.25972/OPUS-17541}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-175415}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2021}, abstract = {G-protein-coupled receptors (GPCRs) regulate diverse physiological processes in the human body and represent prime targets in modern drug discovery. Engagement of different ligands to these membrane-embedded proteins evokes distinct receptor conformational rearrangements that facilitate subsequent receptor-mediated signalling and, ultimately, enable cellular adaptation to altered environmental conditions. Since the early 2000s, the technology of resonance energy transfer (RET) has been exploited to assess these conformational receptor dynamics in living cells and real time. However, to date, these conformational GPCR studies are restricted to single-cell microscopic setups, slowing down the discovery of novel GPCR-directed therapeutics. In this work, we present the development of a novel generalizable high-throughput compatible assay for the direct measurement of GPCR activation and deactivation. By screening a variety of energy partners for fluorescence (FRET) and bioluminescence resonance energy transfer (BRET), we identified a highly sensitive design for an α2A-adrenergic receptor conformational biosensor. This biosensor reports the receptor's conformational change upon ligand binding in a 96-well plate reader format with the highest signal amplitude obtained so far. We demonstrate the capacity of this sensor prototype to faithfully quantify efficacy and potency of GPCR ligands in intact cells and real time. Furthermore, we confirm its universal applicability by cloning and validating five further equivalent GPCR biosensors. To prove the suitability of this new GPCR assay for screening purposes, we measured the well-accepted Z-factor as a parameter for the assay quality. All tested biosensors show excellent Z-factors indicating outstanding assay quality. Furthermore, we demonstrate that this assay provides excellent throughput and presents low rates of erroneous hit identification (false positives and false negatives). Following this phase of assay development, we utilized these biosensors to understand the mechanism and consequences of the postulated modulation of parathyroid hormone receptor 1 (PTHR1) through receptor activity-modifying protein 2 (RAMP2). We found that RAMP2 desensitizes PTHR1, but not the β2-adrenergic receptor (β2AR), for agonist-induced structural changes. This generalizable sensor design offers the first possibility to upscale conformational GPCR studies, which represents the most direct and unbiased approach to monitor receptor activation and deactivation. Therefore, this novel technology provides substantial advantages over currently established methods for GPCR ligand screening. We feel confident that this technology will aid the discovery of novel types of GPCR ligands, help to identify the endogenous ligands of so-called orphan GPCRs and deepen our understanding of the physiological regulation of GPCR function.}, subject = {G-Protein gekoppelte Rezeptoren}, 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} } @phdthesis{Reimann2021, author = {Reimann, Hauke}, title = {Schicksal von Mikrokernen bzw. mikrokernhaltigen Zellen und Bedeutung von Mikrokernen als Biomarker}, doi = {10.25972/OPUS-24010}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-240109}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2021}, abstract = {Mikrokerne sind als wichtiger Biomarker in der Gentoxizit{\"a}tsforschung seit langer Zeit etabliert und ihre Bildung ist mechanistisch gut verstanden, wohingegen das Mikrokernschicksal und die genaue Funktion von Mikrokernen in der Kanzerogenese unzureichend erforscht sind. Um das Schicksal von Mikrokernen und mikrokernhaltigen Zellen {\"u}ber einen l{\"a}ngeren Zeitraum zu untersuchen, wurden HeLa-Zellen, die mit einem GFP-markierten Histon H2B transfiziert worden sind, mittels Lebendzellmikroskopie nach Behandlung mit verschiedenen gentoxischen Agenzien f{\"u}r 96 h untersucht. Parameter wie die Mitose- oder Zelltodrate wurden dabei ebenso wie das Schicksal der Mikrokerne dokumentiert. W{\"a}hrend Persistenz und Reinkorporation von Mikrokernen h{\"a}ufig beobachtet wurden, waren Degradation und Auswurf von Mikrokernen selten bis gar nicht zu sehen. Auch konnte ein Teil der mikrokernhaltigen Zellen {\"u}ber mehrere Zellteilungen persistieren und proliferieren, wodurch die in Mikrokernen manifestierte chromosomale Instabilit{\"a}t unver{\"a}ndert bleiben kann. Ein eindeutiger Substanzeinfluss auf das Mikrokernschicksal konnte nicht ausgemacht werden. Extrusion sollte weiterhin durch Behandlung mit Hydroxyurea oder Cytochalasin B in Kombination mit gentoxischer Behandlung induziert werden, es wurde jedoch kein Effekt auf die Extrusionsrate beobachtet. Degradation wurde mittels γH2AX-Antik{\"o}rperf{\"a}rbung und transduziertem dsRed-markierten Autophagiemarker LC3B in HeLa-H2B-GFP-Zellen untersucht. Trotz erh{\"o}hter DNA-Degradation in Mikrokernen wurde nur selten eine Ko-Lokalisierung mit LC3B beobachtet. Daf{\"u}r gab es in HeLa-H2B-GFP-Zellen, die zus{\"a}tzlich mit dsRed markierten Kernmembranmarker Lamin B1 transduziert worden sind, Anzeichen f{\"u}r eine eingeschr{\"a}nkte Mikrokernmembranintegrit{\"a}t. Weiterhin wurden Zytokinese-Block Mikrokerntests nach Behandlung mit Thebain mit und ohne metabolische Aktivierung sowie Celecoxib und Celecoxibderivaten durchgef{\"u}hrt. Hierbei wurde nach Thebainbehandlung nur ohne metabolische Aktivierung und bei Anwesenheit von Zytotoxizit{\"a}t mehr Mikrokerne gefunden, w{\"a}hrend nach Behandlung mit Celecoxib und Celecoxibderivaten kein Anstieg beobachtet wurde. Zus{\"a}tzlich wurde der Einfluss durch neurodegenerative Ver{\"a}nderungen auf Mundschleimhautzellen in zwei großen Kohorten untersucht, wobei keine Effekte auf die H{\"a}ufigkeit von Mikrokernen oder mikrokernhaltigen Zellen zugeordnet werden konnten, w{\"a}hrend es teilweise bei Parametern, die auf Zytotoxizit{\"a}t hindeuten, zu Ver{\"a}nderungen kam. Es konnte insgesamt gezeigt werden, dass Mikrokerne und mikrokernhaltige Zellen zus{\"a}tzlich zu ihrer Funktion als Biomarker {\"u}ber wenigstens mehrere Zellteilungen bestehen bleiben k{\"o}nnen. Auf diese Weise k{\"o}nnen sie z. B. {\"u}ber Chromothripsis zu einer beschleunigten Kanzerogenese f{\"u}hren, was zu einer schlechten Prognose f{\"u}r Krebspatienten f{\"u}hren kann.}, subject = {Kleinkern}, language = {de} } @phdthesis{Classen2021, author = {Claßen, Alexandra}, title = {The ERK-cascade in the pathophysiology of cardiac hypertrophy}, doi = {10.25972/OPUS-22966}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-229664}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2021}, abstract = {ERK1/2 are known key players in the pathophysiology of heart failure, but the members of the ERK cascade, in particular Raf1, can also protect the heart from cell death and ischemic injury. An additional autophosphorylation (ERK1 at Thr208, ERK2 at Thr188) empowers ERK1/2 translocation to the nucleus and phosphorylation of nuclear targets which take part in the development of cardiac hypertrophy. Thereby, targeting this additional phosphorylation is a promising pharmacological approach. In this thesis, an in silico model of ERK cascade in the cardiomyocyte is introduced. The model is a semi-quantitive model and its behavior was tested with different softwares (SQUAD and CellNetAnalyzer). Different phosphorylation states of ERK1/2 as well as different stimuli can be reproduced. The different types of stimuli include hypertrophic as well as non-hypertrophic stimuli. With the introduced in-silico model time courses and synergistic as well as antagonistic receptor stimuli combinations can be predicted. The simulated time courses were experimentally validated. SQUAD was mainly used to make predictions about time courses and thresholds, whereas CNA was used to analyze steady states and feedback loops. Furthermore, new targets of ERK1/2 which partially contribute, also in the formation of cardiac hypertrophy, were identified and the most promising of them were illuminated. Important further targets are Caspase 8, GAB2, Mxi-2, SMAD2, FHL2 and SPIN90. Cardiomyocyte gene expression data sets were analyzed to verify involved components and to find further significantly altered genes after induced hypertrophy with TAC (transverse aortic constriction). Changes in the ultrastructure of the cardiomyocyte are the final result of induced hypertrophy.}, subject = {Herzhypertrophie}, 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} } @phdthesis{Kreutzmann2021, author = {Kreutzmann, Moritz Paul}, title = {Untersuchung von Markern f{\"u}r oxidativen Stress und DNA-Sch{\"a}den bei arterieller Hypertonie}, doi = {10.25972/OPUS-24338}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-243380}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2021}, abstract = {Patienten mit arterieller Hypertonie haben ein erh{\"o}htes Risiko eine Tumorerkrankung, insbesondere Nierenzellkarzinome, zu entwickeln. Die arterielle Hypertonie ist {\"u}ber die Entstehung von oxidativem Stress mit der Entwicklung von DNA-Sch{\"a}den verkn{\"u}pft, wobei ein hochreguliertes Renin-Angiotensin-Aldosteron-System (RAAS) eine entscheidende Rolle einnimmt. Das Ziel dieser Arbeit war es zum einen Hypertoniker (HypAll) und gesunde Kontrollen und zum anderen gut (HypGut) und schlecht (HypSch) eingestellte Hypertoniker unter Ber{\"u}cksichtigung der eingenommenen Antihypertensiva bez{\"u}glich ihrer Level an oxidativem Stress und DNA-Sch{\"a}den zu vergleichen. Zus{\"a}tzlich erfolgte im Rahmen einer L{\"a}ngsschnittanalyse der intraindividuelle Vergleich unter den Hypertonikern. Hierf{\"u}r erfolgte die Bestimmung von SHp, D-ROM und 3-Nitrotyrosin als Marker f{\"u}r oxidativen Stress im Plasma, von 8-oxodG, 15-F2t-Isoprostan und Malondialdehyd als Marker f{\"u}r oxidativen Stress im Urin und von γ-H2AX und Mikrokernen als Marker f{\"u}r DNA-Sch{\"a}den in Lymphozyten. Dabei konnte ein erh{\"o}hter oxidativer Stress in der HypAll-Gruppe verglichen zu den Kontrollen anhand aller Marker f{\"u}r oxidativen Stress mit Ausnahme von Malondialdehyd festgestellt werden. Nach Altersadjustierung zeigte sich dieser Gruppenunterschied nur noch f{\"u}r die Proteinstressmarker SHp und 3-Nitrotyrosin signifikant. Bez{\"u}glich der Marker f{\"u}r DNA-Sch{\"a}den ergab sich kein Unterschied zwischen HypAll und Kontrollen. Ebenso zeigte sich kein signifikanter Unterschied in den Leveln f{\"u}r oxidativen Stress und DNA-Sch{\"a}den zwischen der HypGut- und HypSch-Gruppe. Zuletzt konnte im Rahmen der L{\"a}ngsschnittstudie ein positiver Zusammenhang zwischen der Entwicklung des Blutdrucks und des oxidativen Stresses anhand der Ver{\"a}nderung von D-ROM und des systolischen Blutdrucks beobachtet werden. Die teils nicht-signifikanten und teils mangelnden Unterschiede zwischen HypAll und Kontrollen sowie zwischen HypGut und HypSch sind am ehesten durch das besondere Patientengut, welches sich auch grundlegend von dem anderer vergleichbarer Studien unterscheidet, erkl{\"a}rbar. Die Patienten mit therapieresistenter Hypertonie (TRH) zeichnen sich durch eine langj{\"a}hrige Einnahme zahlreicher Antihypertensiva aus. Diese, insbesondere die RAAS-wirksamen, besitzen eine {\"u}ber die reine Blutdrucksenkung hinausgehende antioxidative und antigenotoxische Wirkung, welche vermutlich zu einer Angleichung der Level f{\"u}r oxidativen Stress und DNA-Sch{\"a}den gef{\"u}hrt hat. Um die Dynamik der Biomarker und den Einfluss der Antihypertensiva auf oxidativen Stress und DNA-Sch{\"a}den besser zu verstehen, sind weitere Studien {\"u}ber einen l{\"a}ngeren Beobachtungszeitraum sowie mit zus{\"a}tzlich therapienaiven Hypertonikern sinnvoll. Die weitere Erforschung von Biomarkern, um sie im klinischen Alltag zur Verbesserung der Patientenbehandlung einsetzen zu k{\"o}nnen, ist notwendig.}, subject = {Oxidativer Stress}, 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} }