TY - JOUR A1 - Rau, Monika A1 - Schmitt, Johannes A1 - Berg, Thomas A1 - Kremer, Andreas E. A1 - Stieger, Bruno A1 - Spanaus, Katharina A1 - Bengsch, Bertram A1 - Romero, Marta R. A1 - Marin, Jose J. A1 - Keitel, Verena A1 - Klinker, Hartwig A1 - Tony, Hans-Peter A1 - Müllhaupt, Beat A1 - Geier, Andreas T1 - Serum IP-10 levels and increased DPPIV activity are linked to circulating CXCR3+ T cells in cholestatic HCV patients JF - PLoS ONE N2 - Background & aims Serum interferon-gamma-inducible protein-10 (IP-10) is elevated in cholestatic liver diseases and predicts response to antiviral therapy in patients with chronic hepatitis C virus (HCV) infection. Dipeptidylpeptidase 4 (DPPIV) cleaves active IP-10 into an inactive form, which inhibits recruitment of CXCR3+ T cells to the liver. In this study the link between IP-10 levels, DPPIV activity in serum and CXCR3+ T cells is analysed in cholestatic and non-cholestatic liver patients. Methods In serum DPPIV activity (by enzymatic assay), IP-10 (by ELISA) and bile acids (BA) (by enzymatic assay) were analysed in 229 naive HCV genotype (GT) 1 patients and in 16 patients with cholestatic liver disease. In a prospective follow-up (FU) cohort of 27 HCV GT 1 patients peripheral CD3+CXCR3+, CD4+CXCR3+ and CD8+CXCR3+ cells were measured by FACS. Results In 229 HCV patients serum IP-10 levels correlated positively to DPPIV serum activity. Higher IP-10 levels and DPPIV activity were detected in cholestatic and in cirrhotic HCV patients. Increased IP-10 serum levels were associated with therapeutic non-response to antiviral treatment with pegylated-interferon and ribavirin. In the HCV FU cohort elevated IP-10 serum levels and increased BA were associated with higher frequencies of peripheral CD3+CXCR3+, CD4+CXCR3+ and CD8+CXCR3+ T cells. Positive correlation between serum IP-10 levels and DPPIV activity was likewise validated in patients with cholestatic liver diseases. Conclusions A strong correlation between elevated serum levels of IP-10 and DPPIV activity was seen in different cholestatic patient groups. Furthermore, in cholestatic HCV patients a functional link to increased numbers of peripheral CXCR3+ immune cells could be observed. The source of DPPIV release in cholestatic patients remains open. KW - hepatitis C virus KW - T cells KW - liver diseases KW - chemokines KW - cytotoxic T cells KW - immune cells KW - cirrhosis KW - bile Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-177674 VL - 13 IS - 12 ER - TY - JOUR A1 - Raselli, Tina A1 - Hearn, Tom A1 - Wyss, Annika A1 - Atrott, Kirstin A1 - Peter, Alain A1 - Frey-Wagner, Isabelle A1 - Spalinger, Marianne R. A1 - Maggio, Ewerton M. A1 - Sailer, Andreas W. A1 - Schmitt, Johannes A1 - Schreiner, Philipp A1 - Moncsek, Anja A1 - Mertens, Joachim A1 - Scharl, Michael A1 - Griffiths, William J. A1 - Bueter, Marco A1 - Geier, Andreas A1 - Rogler, Gerhard A1 - Wang, Yuqin A1 - Misselwitz, Benjamin T1 - Elevated oxysterol levels in human and mouse livers reflect nonalcoholic steatohepatitis JF - Journal of Lipid Research N2 - Nonalcoholic steatohepatitis (NASH), a primary cause of liver disease, leads to complications such as fibrosis, cirrhosis, and carcinoma, but the pathophysiology of NASH is incompletely understood. Epstein-Barr virus-induced G protein-coupled receptor 2 (EBI2) and its oxysterol ligand 7 alpha,25-dihydroxycholesterol (7 alpha,25-diHC) are recently discovered immune regulators. Several lines of evidence suggest a role of oxysterols in NASH pathogenesis, but rigorous testing has not been performed. We measured oxysterol levels in the livers of NASH patients by LC-MS and tested the role of the EBI2-7 alpha,25-diHC system in a murine feeding model of NASH. Free oxysterol profiling in livers from NASH patients revealed a pronounced increase in 24- and 7-hydroxylated oxysterols in NASH compared with controls. Levels of 24- and 7-hydroxylated oxysterols correlated with histological NASH activity. Histological analysis of murine liver samples demonstrated ballooning and liver inflammation. No significant genotype-related differences were observed in Ebi2(-/-) mice and mice with defects in the 7 alpha,25-diHC synthesizing enzymes CH25H and CYP7B1 compared with wild-type littermate controls, arguing against an essential role of these genes in NASH pathogenesis. Elevated 24- and 7-hydroxylated oxysterol levels were confirmed in murine NASH liver samples. Our results suggest increased bile acid synthesis in NASH samples, as judged by the enhanced level of 7 alpha-hydroxycholest-4-en-3-one and impaired 24S-hydroxycholesterol metabolism as characteristic biochemical changes in livers affected by NASH. KW - nonalcoholic fatty liver disease KW - Epstein-Barr virus-induced gene 2 KW - cholesterol 25 hydroxylase KW - 25-hydroxycholesterol 7 alpha-hydroxylase KW - mouse feeding model Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-225004 VL - 60 IS - 7 ER - TY - JOUR A1 - Goeb, Eva A1 - Schmitt, Johannes A1 - Benavente, Ricardo A1 - Alsheimer, Manfred T1 - Mammalian Sperm Head Formation Involves Different Polarization of Two Novel LINC Complexes N2 - Background: LINC complexes are nuclear envelope bridging protein structures formed by interaction of SUN and KASH proteins. They physically connect the nucleus with the peripheral cytoskeleton and are critically involved in a variety of dynamic processes, such as nuclear anchorage, movement and positioning and meiotic chromosome dynamics. Moreover, they are shown to be essential for maintaining nuclear shape. Findings: Based on detailed expression analysis and biochemical approaches, we show here that during mouse sperm development, a terminal cell differentiation process characterized by profound morphogenic restructuring, two novel distinctive LINC complexes are established. They consist either of spermiogenesis-specific Sun3 and Nesprin1 or Sun1g, a novel non-nuclear Sun1 isoform, and Nesprin3. We could find that these two LINC complexes specifically polarize to opposite spermatid poles likely linking to sperm-specific cytoskeletal structures. Although, as shown in co-transfection / immunoprecipitation experiments, SUN proteins appear to arbitrarily interact with various KASH partners, our study demonstrates that they actually are able to confine their binding to form distinct LINC complexes. Conclusions: Formation of the mammalian sperm head involves assembly and different polarization of two novel spermiogenesis-specific LINC complexes. Together, our findings suggest that theses LINC complexes connect the differentiating spermatid nucleus to surrounding cytoskeletal structures to enable its well-directed shaping and elongation, which in turn is a critical parameter for male fertility. KW - Sperma KW - LINC complexes Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68449 ER - TY - JOUR A1 - Becker, Philip P. A1 - Rau, Monika A1 - Schmitt, Johannes A1 - Malsch, Carolin A1 - Hammer, Christian A1 - Bantel, Heike A1 - Müllhaupt, Beat A1 - Geier, Andreas T1 - Performance of serum microRNAs -122, -192 and -21 as biomarkers in patients with non-alcoholic steatohepatitis JF - PLoS ONE N2 - Objectives Liver biopsies are the current gold standard in non-alcoholic steatohepatitis (NASH) diagnosis. Their invasive nature, however, still carries an increased risk for patients' health. The development of non-invasive diagnostic tools to differentiate between bland steatosis (NAFL) and NASH remains crucial. The aim of this study is the evaluation of investigated circulating microRNAs in combination with new targets in order to optimize the discrimination of NASH patients by non-invasive serum biomarkers. Methods Serum profiles of four microRNAs were evaluated in two cohorts consisting of 137 NAFLD patients and 61 healthy controls. In a binary logistic regression model microRNAs of relevance were detected. Correlation of microRNA appearance with known biomarkers like ALT and CK18-Asp396 was evaluated. A simplified scoring model was developed, combining the levels of microRNA in circulation and CK18-Asp396 fragments. Receiver operating characteristics were used to evaluate the potential of discriminating NASH. Results The new finding of our study is the different profile of circulating miR-21 in NASH patients (p<0.0001). Also, it validates recently published results of miR-122 and miR-192 to be differentially regulated in NAFL and NASH. Combined microRNA expression profiles with CK18-Asp396 fragment level scoring model had a higher potential of NASH prediction compared to other risk biomarkers (AUROC = 0.83, 95% CI = 0.754-0.908; p<0.001). Evaluation of score model for NAFL (Score = 0) and NASH (Score = 4) had shown high rates of sensitivity (91%) and specificity (83%). Conclusions Our study defines candidates for a combined model of miRNAs and CK18-Asp396 levels relevant as a promising expansion for diagnosis and in turn treatment of NASH. KW - fatty liver disease KW - independent marker KW - expression KW - injury KW - NAFLD KW - circulating micrornas KW - caspase activation KW - fibrosis KW - miR-122 KW - apoptosis Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-145147 VL - 10 IS - 11 ER - TY - JOUR A1 - Bankoglu, Ezgi Eyluel A1 - Tschopp, Oliver A1 - Schmitt, Johannes A1 - Burkard, Philipp A1 - Jahn, Daniel A1 - Geier, Andreas A1 - Stopper, Helga T1 - Role of PTEN in Oxidative Stress and DNA Damage in the Liver of Whole-Body Pten Haplodeficient Mice JF - PLoS One N2 - Type 2 diabetes (T2DM) and obesity are frequently associated with non-alcoholic fatty liver disease (NAFLD) and with an elevated cancer incidence. The molecular mechanisms of carcinogenesis in this context are only partially understood. High blood insulin levels are typical in early T2DM and excessive insulin can cause elevated reactive oxygen species (ROS) production and genomic instability. ROS are important for various cellular functions in signaling and host defense. However, elevated ROS formation is thought to be involved in cancer induction. In the molecular events from insulin receptor binding to genomic damage, some signaling steps have been identified, pointing at the PI3K/AKT pathway. For further elucidation Phosphatase and Tensin homolog (Pten), a tumour suppressor phosphatase that plays a role in insulin signaling by negative regulation of PI3K/AKT and its downstream targets, was investigated here. Dihydroethidium (DHE) staining was used to detect ROS formation in immortalized human hepatocytes. Comet assay and micronucleus test were performed to investigate genomic damage in vitro. In liver samples, DHE staining and western blot detection of HSP70 and HO-1 were performed to evaluate oxidative stress response. DNA double strand breaks (DSBs) were detected by immunohistostaining. Inhibition of PTEN with the pharmacologic inhibitor VO-OHpic resulted in increased ROS production and genomic damage in a liver cell line. Knockdown of Pten in a mouse model yielded increased oxidative stress levels, detected by ROS levels and expression of the two stress-proteins HSP70 and HO-1 and elevated genomic damage in the liver, which was significant in mice fed with a high fat diet. We conclude that PTEN is involved in oxidative stress and genomic damage induction in vitro and that this may also explain the in vivo observations. This further supports the hypothesis that the PI3K/AKT pathway is responsible for damaging effects of high levels of insulin. KW - insulin KW - mouse models DNA damage KW - oxidative stress KW - mammalian genomics KW - fatty liver KW - micronuclei KW - insulin signaling Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-146970 VL - 11 IS - 11 ER - TY - JOUR A1 - Alsheimer, Manfred A1 - Link, Jana A1 - Leubner, Monika A1 - Schmitt, Johannes A1 - Göb, Eva A1 - Benavente, Ricardo A1 - Jeang, Kuan-Teh A1 - Xu, Rener T1 - Analysis of Meiosis in SUN1 Deficient Mice Reveals a Distinct Role of SUN2 in Mammalian Meiotic LINC Complex Formation and Function N2 - LINC complexes are evolutionarily conserved nuclear envelope bridges, composed of SUN (Sad-1/UNC-84) and KASH (Klarsicht/ANC-1/Syne/homology) domain proteins. They are crucial for nuclear positioning and nuclear shape determination, and also mediate nuclear envelope (NE) attachment of meiotic telomeres, essential for driving homolog synapsis and recombination. In mice, SUN1 and SUN2 are the only SUN domain proteins expressed during meiosis, sharing their localization with meiosis-specific KASH5. Recent studies have shown that loss of SUN1 severely interferes with meiotic processes. Absence of SUN1 provokes defective telomere attachment and causes infertility. Here, we report that meiotic telomere attachment is not entirely lost in mice deficient for SUN1, but numerous telomeres are still attached to the NE through SUN2/KASH5-LINC complexes. In Sun12/2 meiocytes attached telomeres retained the capacity to form bouquetlike clusters. Furthermore, we could detect significant numbers of late meiotic recombination events in Sun12/2 mice. Together, this indicates that even in the absence of SUN1 telomere attachment and their movement within the nuclear envelope per se can be functional. Author summary: Correct genome haploidization during meiosis requires tightly regulated chromosome movements that follow a highly conserved choreography during prophase I. Errors in these movements cause subsequent meiotic defects, which typically lead to infertility. At the beginning of meiotic prophase, chromosome ends are tethered to the nuclear envelope (NE). This attachment of telomeres appears to be mediated by well-conserved membrane spanning protein complexes within the NE (LINC complexes). In mouse meiosis, the two main LINC components SUN1 and SUN2 were independently described to localize at the sites of telomere attachment. While SUN1 has been demonstrated to be critical for meiotic telomere attachment, the precise role of SUN2 in this context, however, has been discussed controversially in the field. Our current study was targeted to determine the factual capacity of SUN2 in telomere attachment and chromosome movements in SUN1 deficient mice. Remarkably, although telomere attachment is impaired in the absence of SUN1, we could find a yet undescribed SUN1-independent telomere attachment, which presumably is mediated by SUN2 and KASH5. This SUN2 mediated telomere attachment is stable throughout prophase I and functional in moving telomeres within the NE. Thus, our results clearly indicate that SUN1 and SUN2, at least partially, fulfill redundant meiotic functions. KW - telomeres KW - spermatocytes KW - Oocytes KW - meiosis KW - protein domains KW - cytoskeleton KW - synapsis KW - homologous chromosomes Y1 - 2014 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-111355 ER - TY - JOUR A1 - Alsheimer, Manfred A1 - Link, Jana A1 - Jahn, Daniel A1 - Schmitt, Johannes A1 - Göb, Eva A1 - Baar, Johannes A1 - Ortega, Sagrario A1 - Benavente, Ricardo T1 - The Meiotic Nuclear Lamina Regulates Chromosome Dynamics and Promotes Efficient Homologous Recombination in the Mouse JF - PLoS Genetics N2 - The nuclear lamina is the structural scaffold of the nuclear envelope and is well known for its central role in nuclear organization and maintaining nuclear stability and shape. In the past, a number of severe human disorders have been identified to be associated with mutations in lamins. Extensive research on this topic has provided novel important clues about nuclear lamina function. These studies have contributed to the knowledge that the lamina constitutes a complex multifunctional platform combining both structural and regulatory functions. Here, we report that, in addition to the previously demonstrated significance for somatic cell differentiation and maintenance, the nuclear lamina is also an essential determinant for germ cell development. Both male and female mice lacking the short meiosis-specific A-type lamin C2 have a severely defective meiosis, which at least in the male results in infertility. Detailed analysis revealed that lamin C2 is required for telomere-driven dynamic repositioning of meiotic chromosomes. Loss of lamin C2 affects precise synapsis of the homologs and interferes with meiotic double-strand break repair. Taken together, our data explain how the nuclear lamina contributes to meiotic chromosome behaviour and accurate genome haploidization on a mechanistic level. KW - homologous chromosomes KW - homologous recombination KW - lamins KW - Oocytes KW - spermatocytes KW - synapsis KW - telomeres KW - testes Y1 - 2013 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-96285 ER -