TY - JOUR A1 - Thierbach, René A1 - Drewes, Gunnar A1 - Fusser, Markus A1 - Voigt, Anja A1 - Kuhlow, Doreen A1 - Blume, Urte A1 - Schulz, Tim Julius A1 - Reiche, Carina A1 - Glatt, Hansruedi A1 - Epe, Bernd A1 - Steinberg, Pablo A1 - Ristow, Michael T1 - The Friedreich's ataxia protein frataxin modulates DNA base excision repair in prokaryotes and mammals N2 - DNA-repair mechanisms enable cells to maintain their genetic information by protecting it from mutations that may cause malignant growth. Recent evidence suggests that specific DNA-repair enzymes contain ISCs (iron-sulfur clusters). The nuclear-encoded protein frataxin is essential for the mitochondrial biosynthesis of ISCs. Frataxin deficiency causes a neurodegenerative disorder named Friedreich's ataxia in humans. Various types of cancer occurring at young age are associated with this disease, and hence with frataxin deficiency. Mice carrying a hepatocyte- specific disruption of the frataxin gene develop multiple liver tumours for unresolved reasons. In the present study, we show that frataxin deficiency in murine liver is associated with increased basal levels of oxidative DNA base damage. Accordingly, eukaryotic V79 fibroblasts overexpressing human frataxin show decreased basal levels of these modifications, while prokaryotic Salmonella enterica serotype Typhimurium TA 104 strains transformed with human frataxin show decreased mutation rates. The repair rates of oxidative DNA base modifications in V79 cells overexpressing frataxin were significantly higher than in control cells. Lastly, cleavage activity related to the ISC-independent repair enzyme 8-oxoguanine glycosylase was found to be unaltered by frataxin overexpression. These findings indicate that frataxin modulates DNA-repair mechanisms probably due to its impact on ISC-dependent repair proteins, linking mitochondrial dysfunction to DNA repair and tumour initiation. Y1 - 2010 UR - http://www.biochemj.org/bj/toc.htm U6 - https://doi.org/10.1042/Bj20101116 SN - 0264-6021 ER - TY - JOUR A1 - Rufer, CE A1 - Glatt, Hansruedi A1 - Kulling, Sabine E. T1 - Structural elucidation of hydroxylated metabolites of the isoflavan equol by gas chromatography-mass spectrometry and high-performance liquid chromatography-mass spectrometry N2 - Equol has, as have other isoflavonoids, recently gained considerable interest due to its possible health effects. However, detailed studies on the metabolism of equol are scarce. Therefore, we investigated the phase I metabolism of equol using liver microsomes from Aroclor-treated male Wistar rats as well as from a male human. The identification of the metabolites formed was elucidated using high performance liquid chromatography ( HPLC) with diode array detection, HPLC/atmospheric pressure ionization electrospray mass spectrometry, and gas chromatography-mass spectrometry, as well as reference compounds. ( +/-)-Equol was converted to 11 metabolites by the liver microsomes from Aroclorpretreated rats comprising three aromatic monohydroxylated and four aliphatic monohydroxylated as well as four dihydroxylated products. The main metabolite was identified as 3'-hydroxy-equol. Using human liver microsomes, equol was converted to six metabolites with 3'-hydroxy- and 6-hydroxy-equol as main products. Furthermore, the aliphatic hydroxylated metabolite 4-hydroxyequol, which was recently detected in human urine after soy consumption, was formed. On the basis of these findings, it is suggested that phase I metabolism of equol is part of a complex biotransformation of the soy isoflavone daidzein in humans in vivo Y1 - 2006 U6 - https://doi.org/10.1124/dmd.105.004929 ER - TY - JOUR A1 - Gronke, Konrad A1 - Hernandez, Pedro P. A1 - Zimmermann, Jakob A1 - Klose, Christoph S. N. A1 - Kofoed-Branzk, Michael A1 - Guendel, Fabian A1 - Witkowski, Mario A1 - Tizian, Caroline A1 - Amann, Lukas A1 - Schumacher, Fabian A1 - Glatt, Hansruedi A1 - Triantafyllopoulou, Antigoni A1 - Diefenbach, Andreas T1 - Interleukin-22 protects intestinal stem cells against genotoxic stress JF - Nature : the international weekly journal of science N2 - Environmental genotoxic factors pose a challenge to the genomic integrity of epithelial cells at barrier surfaces that separate host organisms from the environment. They can induce mutations that, if they occur in epithelial stem cells, contribute to malignant transformation and cancer development1,2,3. Genome integrity in epithelial stem cells is maintained by an evolutionarily conserved cellular response pathway, the DNA damage response (DDR). The DDR culminates in either transient cell-cycle arrest and DNA repair or elimination of damaged cells by apoptosis4,5. Here we show that the cytokine interleukin-22 (IL-22), produced by group 3 innate lymphoid cells (ILC3) and γδ T cells, is an important regulator of the DDR machinery in intestinal epithelial stem cells. Using a new mouse model that enables sporadic inactivation of the IL-22 receptor in colon epithelial stem cells, we demonstrate that IL-22 is required for effective initiation of the DDR following DNA damage. Stem cells deprived of IL-22 signals and exposed to carcinogens escaped DDR-controlled apoptosis, contained more mutations and were more likely to give rise to colon cancer. We identified metabolites of glucosinolates, a group of phytochemicals contained in cruciferous vegetables, to be a widespread source of genotoxic stress in intestinal epithelial cells. These metabolites are ligands of the aryl hydrocarbon receptor (AhR)6, and AhR-mediated signalling in ILC3 and γδ T cells controlled their production of IL-22. Mice fed with diets depleted of glucosinolates produced only very low levels of IL-22 and, consequently, the DDR in epithelial cells of mice on a glucosinolate-free diet was impaired. This work identifies a homeostatic network protecting stem cells against challenge to their genome integrity by AhR-mediated ‘sensing’ of genotoxic compounds from the diet. AhR signalling, in turn, ensures on-demand production of IL-22 by innate lymphocytes directly regulating components of the DDR in epithelial stem cells. Y1 - 2019 U6 - https://doi.org/10.1038/s41586-019-0899-7 SN - 0028-0836 SN - 1476-4687 VL - 566 IS - 7743 SP - 249 EP - 253 PB - Nature Publ. Group CY - London ER - TY - JOUR A1 - Rakers, Christin A1 - Schumacher, Fabian A1 - Meinl, Walter A1 - Glatt, Hansruedi A1 - Kleuser, Burkhard A1 - Wolber, Gerhard T1 - In Silico Prediction of Human Sulfotransferase 1E1 Activity Guided by Pharmacophores from Molecular Dynamics Simulations JF - The journal of biological chemistry N2 - Acting during phase II metabolism, sulfotransferases (SULTs) serve detoxification by transforming a broad spectrum of compounds from pharmaceutical, nutritional, or environmental sources into more easily excretable metabolites. However, SULT activity has also been shown to promote formation of reactive metabolites that may have genotoxic effects. SULT subtype 1E1 (SULT1E1) was identified as a key player in estrogen homeostasis, which is involved in many physiological processes and the pathogenesis of breast and endometrial cancer. The development of an in silico prediction model for SULT1E1 ligands would therefore support the development of metabolically inert drugs and help to assess health risks related to hormonal imbalances. Here, we report on a novel approach to develop a model that enables prediction of substrates and inhibitors of SULT1E1. Molecular dynamics simulations were performed to investigate enzyme flexibility and sample protein conformations. Pharmacophores were developed that served as a cornerstone of the model, and machine learning techniques were applied for prediction refinement. The prediction model was used to screen the DrugBank (a database of experimental and approved drugs): 28% of the predicted hits were reported in literature as ligands of SULT1E1. From the remaining hits, a selection of nine molecules was subjected to biochemical assay validation and experimental results were in accordance with the in silico prediction of SULT1E1 inhibitors and substrates, thus affirming our prediction hypotheses. KW - drug design KW - drug metabolism KW - liver metabolism KW - molecular dynamics KW - molecular modeling KW - sulfotransferase Y1 - 2016 U6 - https://doi.org/10.1074/jbc.M115.685610 SN - 0021-9258 SN - 1083-351X VL - 291 SP - 58 EP - 71 PB - American Society for Biochemistry and Molecular Biology CY - Bethesda ER - TY - JOUR A1 - Wiesner-Reinhold, Melanie A1 - Barknowitz, Gitte A1 - Florian, Simone A1 - Mewis, Inga A1 - Schumacher, Fabian A1 - Schreiner, Monika A1 - Glatt, Hansruedi T1 - 1-Methoxy-3-indolylmethyl DNA adducts in six tissues, and blood protein adducts, in mice under pak choi diet: time course and persistence JF - Archives of toxicology : official journal of EUROTOX N2 - We previously showed that purified 1-methoxy-3-indolylmethyl (1-MIM) glucosinolate, a secondary plant metabolite in Brassica species, is mutagenic in various in vitro systems and forms DNA and protein adducts in mouse models. In the present study, we administered 1-MIM glucosinolate in a natural matrix to mice, by feeding a diet containing pak choi powder and extract. Groups of animals were killed after 1, 2, 4 and 8 days of pak choi diet, directly or, in the case of the 8-day treatment, after 0, 8 and 16 days of recovery with pak choi-free diet. DNA adducts [N-2-(1-MIM)-dG, N-6-(1-MIM)-dA] in six tissues, as well as protein adducts [tau N-(1-MIM)-His] in serum albumin (SA) and hemoglobin (Hb) were determined using UPLC-MS/MS with isotopically labeled internal standards. None of the samples from the 12 control animals under standard diet contained any 1-MIM adducts. All groups receiving pak choi diet showed DNA adducts in all six tissues (exception: lung of mice treated for a single day) as well as SA and Hb adducts. During the feeding period, all adduct levels continuously increased until day 8 (in the jejunum until day 4). During the 14-day recovery period, N-2-(1-MIM)-dG in liver, kidney, lung, jejunum, cecum and colon decreased to 52, 41, 59, 11, 7 and 2%, respectively, of the peak level. The time course of N-6-(1-MIM)-dA was similar. Immunohistochemical analyses indicated that cell turnover is a major mechanism of DNA adduct elimination in the intestine. In the same recovery period, protein adducts decreased more rapidly in SA than in Hb, to 0.7 and 37%, respectively, of the peak level, consistent with the differential turnover of these proteins. In conclusion, the pak choi diet lead to the formation of high levels of adducts in mice. Cell and protein turnover was a major mechanism of adduct elimination, at least in gut and blood. KW - 1-Methoxy-3-indolylmethyl glucosinolate KW - Neoglucobrassicin KW - DNA adducts KW - Blood protein adducts KW - Pak choi Y1 - 2019 U6 - https://doi.org/10.1007/s00204-019-02452-3 SN - 0340-5761 SN - 1432-0738 VL - 93 IS - 6 SP - 1515 EP - 1527 PB - Springer CY - Heidelberg ER -