@article{AvotadeLiraSchneiderSchaulies2019, author = {Avota, Elita and de Lira, Maria Nathalia and Schneider-Schaulies, Sibylle}, title = {Sphingomyelin breakdown in T cells: role of membrane compartmentalization in T cell signaling and interference by a pathogen}, series = {Frontiers in Cell and Developmental Biology}, volume = {7}, journal = {Frontiers in Cell and Developmental Biology}, number = {152}, issn = {2296-634X}, doi = {10.3389/fcell.2019.00152}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-199168}, year = {2019}, abstract = {Sphingolipids are major components of cellular membranes, and at steady-state level, their metabolic fluxes are tightly controlled. On challenge by external signals, they undergo rapid turnover, which substantially affects the biophysical properties of membrane lipid and protein compartments and, consequently, signaling and morphodynamics. In T cells, external cues translate into formation of membrane microdomains where proximal signaling platforms essential for metabolic reprograming and cytoskeletal reorganization are organized. This review will focus on sphingomyelinases, which mediate sphingomyelin breakdown and ensuing ceramide release that have been implicated in T-cell viability and function. Acting at the sphingomyelin pool at the extrafacial or cytosolic leaflet of cellular membranes, acid and neutral sphingomyelinases organize ceramide-enriched membrane microdomains that regulate T-cell homeostatic activity and, upon stimulation, compartmentalize receptors, membrane proximal signaling complexes, and cytoskeletal dynamics as essential for initiating T-cell motility and interaction with endothelia and antigen-presenting cells. Prominent examples to be discussed in this review include death receptor family members, integrins, CD3, and CD28 and their associated signalosomes. Progress made with regard to experimental tools has greatly aided our understanding of the role of bioactive sphingolipids in T-cell biology at a molecular level and of targets explored by a model pathogen (measles virus) to specifically interfere with their physiological activity.}, language = {en} } @article{MuenchHsinFerberetal.2016, author = {M{\"u}nch, Miriam and Hsin, Chih-Hsuan and Ferber, Elena and Berger, Susanne and M{\"u}ller, Martin J.}, title = {Reactive electrophilic oxylipins trigger a heat stress-like response through HSFA1 transcription factors}, series = {Journal of Experimental Botany}, volume = {67}, journal = {Journal of Experimental Botany}, number = {21}, doi = {10.1093/jxb/erw376}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-186766}, pages = {6139-6148}, year = {2016}, abstract = {Electrophilic oxylipins trigger a heat-shock-like response in the absence of heat through the canonical heat-shock transcription factor A1, thereby helping to cope with stresses associated with protein damage.Abiotic and biotic stresses are often characterized by an induction of reactive electrophile species (RES) such as the jasmonate 12-oxo-phytodienoic acid (OPDA) or the structurally related phytoprostanes. Previously, RES oxylipins have been shown massively to induce heat-shock-response (HSR) genes including HSP101 chaperones. Moreover, jasmonates have been reported to play a role in basal thermotolerance. We show that representative HSR marker genes are strongly induced by RES oxylipins through the four master regulator transcription factors HSFA1a, b, d, and e essential for short-term adaptation to heat stress in Arabidopsis. When compared with Arabidopsis seedlings treated at the optimal acclimation temperature of 37 A degrees C, the exogenous application of RES oxylipins at 20 A degrees C induced a much weaker induction of HSP101 at both the gene and protein expression levels which, however, was not sufficient to confer short-term acquired thermotolerance. Moreover, jasmonate-deficient mutant lines displayed a wild-type-like HSR and were not compromised in acquiring thermotolerance. Hence, the OPDA- and RES oxylipin-induced HSR is not sufficient to protect seedlings from severe heat stress but may help plants to cope better with stresses associated with protein unfolding by inducing a battery of chaperones in the absence of heat.}, language = {en} } @article{BerntRangrezEdenetal.2016, author = {Bernt, Alexander and Rangrez, Ashraf Y. and Eden, Matthias and Jungmann, Andreas and Katz, Sylvia and Rohr, Claudia and M{\"u}ller, Oliver J. and Katus, Hugo A. and Sossalla, Samuel T. and Williams, Tatjana and Ritter, Oliver and Frank, Derk and Frey, Norbert}, title = {Sumoylation-independent activation of Calcineurin-NFAT-signaling via SUMO2 mediates cardiomyocyte hypertrophy}, series = {Scientific Reports}, volume = {6}, journal = {Scientific Reports}, number = {35758}, doi = {10.1038/srep35758}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-167525}, year = {2016}, abstract = {The objective of this study was to identify unknown modulators of Calcineurin (Cn)-NFAT signaling. Measurement of NFAT reporter driven luciferase activity was therefore utilized to screen a human cardiac cDNA-library (~10\(^{7}\) primary clones) in C2C12 cells through serial dilutions until single clones could be identified. This extensive screening strategy culminated in the identification of SUMO2 as a most efficient Cn-NFAT activator. SUMO2-mediated activation of Cn-NFAT signaling in cardiomyocytes translated into a hypertrophic phenotype. Prohypertrophic effects were also observed in mice expressing SUMO2 in the heart using AAV9 (Adeno-associated virus), complementing the in vitro findings. In addition, increased SUMO2-mediated sumoylation in human cardiomyopathy patients and in mouse models of cardiomyopathy were observed. To decipher the underlying mechanism, we generated a sumoylation-deficient SUMO2 mutant (ΔGG). Surprisingly, ΔGG replicated Cn-NFAT-activation and the prohypertrophic effects of native SUMO2, both in vitro and in vivo, suggesting a sumoylation-independent mechanism. Finally, we discerned a direct interaction between SUMO2 and CnA, which promotes CnA nuclear localization. In conclusion, we identified SUMO2 as a novel activator of Cn-NFAT signaling in cardiomyocytes. In broader terms, these findings reveal an unexpected role for SUMO2 in cardiac hypertrophy and cardiomyopathy, which may open the possibility for therapeutic manipulation of this pathway.}, language = {en} } @article{FirdessaGoodAmstaldenetal.2015, author = {Firdessa, Rebuma and Good, Liam and Amstalden, Maria Cecilia and Chindera, Kantaraja and Kamaruzzaman, Nor Fadhilah and Schultheis, Martina and R{\"o}ger, Bianca and Hecht, Nina and Oelschlaeger, Tobias A. and Meinel, Lorenz and L{\"u}hmann, Tessa and Moll, Heidrun}, title = {Pathogen- and host-directed antileishmanial effects mediated by polyhexanide (PHMB)}, series = {PLoS Neglected Tropical Diseases}, volume = {9}, journal = {PLoS Neglected Tropical Diseases}, number = {10}, doi = {10.1371/journal.pntd.0004041}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148162}, pages = {e0004041}, year = {2015}, abstract = {Background Cutaneous leishmaniasis (CL) is a neglected tropical disease caused by protozoan parasites of the genus Leishmania. CL causes enormous suffering in many countries worldwide. There is no licensed vaccine against CL, and the chemotherapy options show limited efficacy and high toxicity. Localization of the parasites inside host cells is a barrier to most standard chemo- and immune-based interventions. Hence, novel drugs, which are safe, effective and readily accessible to third-world countries and/or drug delivery technologies for effective CL treatments are desperately needed. Methodology/Principal Findings Here we evaluated the antileishmanial properties and delivery potential of polyhexamethylene biguanide (PHMB; polyhexanide), a widely used antimicrobial and wound antiseptic, in the Leishmania model. PHMB showed an inherent antileishmanial activity at submicromolar concentrations. Our data revealed that PHMB kills Leishmania major (L. major) via a dual mechanism involving disruption of membrane integrity and selective chromosome condensation and damage. PHMB's DNA binding and host cell entry properties were further exploited to improve the delivery and immunomodulatory activities of unmethylated cytosine-phosphate-guanine oligodeoxynucleotides (CpG ODN). PHMB spontaneously bound CpG ODN, forming stable nanopolyplexes that enhanced uptake of CpG ODN, potentiated antimicrobial killing and reduced host cell toxicity of PHMB. Conclusions Given its low cost and long history of safe topical use, PHMB holds promise as a drug for CL therapy and delivery vehicle for nucleic acid immunomodulators.}, language = {en} } @article{HausmannBrandtKoecheletal.2015, author = {Hausmann, Stefan and Brandt, Evelyn and K{\"o}chel, Carolin and Einsele, Hermann and Bargou, Ralf C. and Seggewiss-Bernhardt, Ruth and St{\"u}hmer, Thorsten}, title = {Loss of serum and glucocorticoid-regulated kinase 3 (SGK3) does not affect proliferation and survival of multiple myeloma cell lines}, series = {PLoS ONE}, volume = {10}, journal = {PLoS ONE}, number = {4}, doi = {10.1371/journal.pone.0122689}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-148708}, pages = {e0122689}, year = {2015}, abstract = {Multiple myeloma (MM) is a generally fatal plasma cell cancer that often shows activation of the phosphoinositide 3-kinase/Akt (PI3K/Akt) pathway. Targeted pharmacologic therapies, however, have not yet progressed beyond the clinical trial stage, and given the complexity of the PI3K/Akt signalling system (e.g. multiple protein isoforms, diverse feedback regulation mechanisms, strong variability between patients) it is mandatory to characterise its ramifications in order to better guide informed decisions about the best therapeutic approaches. Here we explore whether serum and glucocorticoid-regulated kinase 3 (SGK3), a potential downstream effector of PI3K, plays a role in oncogenic signalling in MM cells-either in concert with or independent of Akt. SGK3 was expressed in all MM cell lines and in all primary MM samples tested. Four MM cell lines representing a broad range of intrinsic Akt activation (very strong: MM. 1s, moderate: L 363 and JJN-3, absent: AMO-1) were chosen to test the effects of transient SGK3 knockdown alone and in combination with pharmacological inhibition of Akt, PI3K-p110\(\alpha\), or in the context of serum starvation. Although the electroporation protocol led to strong SGK3 depletion for at least 5 days its absence had no substantial effect on the activation status of potential downstream substrates, or on the survival, viability or proliferation of MM cells in all experimental contexts tested. We conclude that it is unlikely that SGK3 plays a significant role for oncogenic signalling in multiple myeloma.}, language = {en} } @article{MezianeMoiselloPerfettietal.2015, author = {Meziane, Hadj Boumediene and Moisello, Clara and Perfetti, Bernardo and Kvint, Svetlana and Isaias, Ioannis Ugo and Quartarone, Angelo and Di Rocco, Alessandro and Ghilardi, Maria Felice}, title = {Movement preparation and bilateral modulation of beta activity in aging and Parkinson's disease}, series = {PLoS ONE}, volume = {10}, journal = {PLoS ONE}, number = {1}, doi = {10.1371/journal.pone.0114817}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-144147}, pages = {e0114817}, year = {2015}, abstract = {In previous studies of young subjects performing a reaction-time reaching task, we found that faster reaction times are associated with increased suppression of beta power over primary sensorimotor areas just before target presentation. Here we ascertain whether such beta decrease similarly occurs in normally aging subjects and also in patients with Parkinson's disease (PD), where deficits in movement execution and abnormalities of beta power are usually present. We found that in both groups, beta power decreased during the motor task in the electrodes over the two primary sensorimotor areas. However, before target presentation, beta decreases in PD were significantly smaller over the right than over the left areas, while they were symmetrical in controls. In both groups, functional connectivity between the two regions, measured with imaginary coherence, increased before the target appearance; however, in PD, it decreased immediately after, while in controls, it remained elevated throughout motor planning. As in previous studies with young subjects, the degree of beta power before target appearance correlated with reaction time. The values of coherence during motor planning, instead, correlated with movement time, peak velocity and acceleration. We conclude that planning of prompt and fast movements partially depends on coordinated beta activity of both sensorimotor areas, already at the time of target presentation. The delayed onset of beta decreases over the right region observed in PD is possibly related to a decreased functional connectivity between the two areas, and this might account for deficits in force programming, movement duration and velocity modulation.}, language = {en} } @article{AtakLanglhoferSchaeferetal.2015, author = {Atak, Sinem and Langlhofer, Georg and Schaefer, Natascha and Kessler, Denise and Meiselbach, Heike and Delto, Carolyn and Schindelin, Hermann and Villmann, Carmen}, title = {Disturbances of ligand potency and enhanced degradation of the human glycine receptor at affected positions G160 and T162 originally identified in patients suffering from hyperekplexia}, series = {Frontiers in Molecular Neuroscience}, volume = {8}, journal = {Frontiers in Molecular Neuroscience}, number = {79}, doi = {10.3389/fnmol.2015.00079}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-144818}, year = {2015}, abstract = {Ligand-binding of Cys-loop receptors is determined by N-terminal extracellular loop structures from the plus as well as from the minus side of two adjacent subunits in the pentameric receptor complex. An aromatic residue in loop B of the glycine receptor (GIyR) undergoes direct interaction with the incoming ligand via a cation-π interaction. Recently, we showed that mutated residues in loop B identified from human patients suffering from hyperekplexia disturb ligand-binding. Here, we exchanged the affected human residues by amino acids found in related members of the Cys-loop receptor family to determine the effects of side chain volume for ion channel properties. GIyR variants were characterized in vitro following transfection into cell lines in order to analyze protein expression, trafficking, degradation and ion channel function. GIyR α1 G160 mutations significantly decrease glycine potency arguing for a positional effect on neighboring aromatic residues and consequently glycine-binding within the ligand-binding pocket. Disturbed glycinergic inhibition due to T162 α1 mutations is an additive effect of affected biogenesis and structural changes within the ligand-binding site. Protein trafficking from the ER toward the ER-Golgi intermediate compartment, the secretory Golgi pathways and finally the cell surface is largely diminished, but still sufficient to deliver ion channels that are functional at least at high glycine concentrations. The majority of T162 mutant protein accumulates in the ER and is delivered to ER-associated proteasomal degradation. Hence, G160 is an important determinant during glycine binding. In contrast, 1162 affects primarily receptor biogenesis whereas exchanges in functionality are secondary effects thereof.}, language = {en} } @article{RodriguezRicoYepesetal.2015, author = {Rodriguez, H{\´e}ctor and Rico, Sergio and Yepes, Ana and Franco-Echevarr{\´i}a, Elsa and Antoraz, Sergio and Santamar{\´i}a, Ram{\´o}n I. and D{\´i}az, Margerita}, title = {The two kinases, AbrC1 and AbrC2, of the atypical two-component system AbrC are needed to regulate antibiotic production and differentiation in Streptomyces coelicolor}, series = {Frontiers in Microbiology}, volume = {6}, journal = {Frontiers in Microbiology}, number = {450}, doi = {10.3389/fmicb.2015.00450}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-143048}, year = {2015}, abstract = {Two-component systems (TCSs) are the most important sensing mechanisms in bacteria. In Streptomyces, TCSs-mediated responses to environmental stimuli are involved in the regulation of antibiotic production. This study examines the individual role of two histidine kinases (HKs), AbrC1 and AbrC2, which form part of an atypical TCS in Streptomyces coelicolor. gRT-PCR analysis of the expression of both kinases demonstrated that both are expressed at similar levels in NB and NMMP media. Single deletion of abrC1 elicited a significant increase in antibiotic production, while deletion of abrC2 did not have any clear effect. The origin of this phenotype, probably related to the differential phosphorylation ability of the two kinases, was also explored indirectly, analyzing the toxic phenotypes associated with high levels of phosphorylated RR. The higher the AbrC3 regulator phosphorylation rate, the greater the cell toxicity. For the first time, the present work shows in Streptomyces the combined involvement of two different HKs in the response of a regulator to environmental signals. Regarding the possible applications of this research, the fact that an abrC1 deletion mutant overproduces three of the S. coelicolor antibiotics makes this strain an excellent candidate as a host for the heterologous production of secondary metabolites.}, language = {en} } @article{WunschZhangHansonetal.2015, author = {Wunsch, Marie and Zhang, Wenji and Hanson, Jodi and Caspell, Richard and Karulin, Alexey Y. and Recks, Mascha S. and Kuerten, Stefanie and Sundararaman, Srividya and Lehmann, Paul V.}, title = {Characterization of the HCMV-Specific CD4 T Cell Responses that Are Associated with Protective Immunity}, series = {Viruses}, volume = {7}, journal = {Viruses}, doi = {10.3390/v7082828}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-151462}, pages = {4414 -- 4437}, year = {2015}, abstract = {Most humans become infected with human cytomegalovirus (HCMV). Typically, the immune system controls the infection, but the virus persists and can reactivate in states of immunodeficiency. While substantial information is available on the contribution of CD8 T cells and antibodies to anti-HCMV immunity, studies of the T\(_{H}\)1, T\(_{H}\)2, and T\(_{H}\)17 subsets have been limited by the low frequency of HCMV-specific CD4 T cells in peripheral blood mononuclear cell (PBMC). Using the enzyme-linked Immunospot\(^{®}\) assay (ELISPOT) that excels in low frequency measurements, we have established these in a sizable cohort of healthy HCMV controllers. Cytokine recall responses were seen in all seropositive donors. Specifically, interferon (IFN)-\({\gamma}\) and/or interleukin (IL)-17 were seen in isolation or with IL-4 in all test subjects. IL-4 recall did not occur in isolation. While the ratios of T\(_{H}\)1, T\(_{H}\)2, and T\(_{H}\)17 cells exhibited substantial variations between different individuals these ratios and the frequencies were relatively stable when tested in samples drawn up to five years apart. IFN-\({\gamma}\) and IL-2 co-expressing polyfunctional cells were seen in most subjects. Around half of the HCMV-specific CD4 cells were in a reversible state of exhaustion. The data provided here established the T\(_{H}\)1, T\(_{H}\)2, and T\(_{H}\)17 characteristic of the CD4 cells that convey immune protection for successful immune surveillance against which reactivity can be compared when the immune surveillance of HCMV fails.}, language = {en} } @article{NguyenKraftYuetal.2015, author = {Nguyen, Minh Thu and Kraft, Beatrice and Yu, Wenqi and Demicrioglu, Dogan Doruk and Hertlein, Tobias and Burian, Marc and Schmaler, Mathias and Boller, Klaus and Bekeredjian-Ding, Isabelle and Ohlsen, Knut and Schittek, Birgit and G{\"o}tz, Friedrich}, title = {The vSa\(\alpha\) Specific Lipoprotein Like Cluster (lpl) of S. aureus USA300 Contributes to Immune Stimulation and Invasion in Human Cells}, series = {PLoS Pathogens}, volume = {11}, journal = {PLoS Pathogens}, number = {6}, doi = {10.1371/journal.ppat.1004984}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-151856}, pages = {e1004984}, year = {2015}, abstract = {All Staphylococcus aureus genomes contain a genomic island, which is termed vSa\(\alpha\) and characterized by two clusters of tandem repeat sequences, i.e. the exotoxin (set) and 'lipoprotein-like' genes (lpl). Based on their structural similarities the vSa\(\alpha\) islands have been classified as type I to IV. The genomes of highly pathogenic and particularly epidemic S. aureus strains (USA300, N315, Mu50, NCTC8325, Newman, COL, JH1 or JH9) belonging to the clonal complexes CC5 and CC8 bear a type I vSa\(\alpha\) island. Since the contribution of the lpl gene cluster encoded in the vSa\(\alpha\) island to virulence is unclear to date, we deleted the entire lpl gene cluster in S. aureus USA300. The results showed that the mutant was deficient in the stimulation of pro-inflammatory cytokines in human monocytes, macrophages and keratinocytes. Purified lipoprotein Lpl1 was further shown to elicit a TLR2-dependent response. Furthermore, heterologous expression of the USA300 lpl cluster in other S. aureus strains enhanced their immune stimulatory activity. Most importantly, the lpl cluster contributed to invasion of S. aureus into human keratinocytes and mouse skin and the non-invasive S. carnosus expressing the lpl gene cluster became invasive. Additionally, in a murine kidney abscess model the bacterial burden in the kidneys was higher in wild type than in mutant mice. In this infection model the lpl cluster, thus, contributes to virulence. The present report is one of the first studies addressing the role of the vSa\(\alpha\) encoded lpl gene cluster in staphylococcal virulence. The finding that the lpl gene cluster contributes to internalization into non-professional antigen presenting cells such as keratinocytes high-lights the lpl as a new cell surface component that triggers host cell invasion by S. aureus. Increased invasion in murine skin and an increased bacterial burden in a murine kidney abscess model suggest that the lpl gene cluster serves as an important virulence factor.}, language = {en} }