TY - JOUR A1 - Meinert, Madlen A1 - Jessen, Christina A1 - Hufnagel, Anita A1 - Kreß, Julia Katharina Charlotte A1 - Burnworth, Mychal A1 - Däubler, Theo A1 - Gallasch, Till A1 - Da Xavier Silva, Thamara Nishida A1 - Dos Santos, Ancély Ferreira A1 - Ade, Carsten Patrick A1 - Schmitz, Werner A1 - Kneitz, Susanne A1 - Friedmann Angeli, José Pedro A1 - Meierjohann, Svenja T1 - Thiol starvation triggers melanoma state switching in an ATF4 and NRF2-dependent manner JF - Redox Biology N2 - The cystine/glutamate antiporter xCT is an important source of cysteine for cancer cells. Once taken up, cystine is reduced to cysteine and serves as a building block for the synthesis of glutathione, which efficiently protects cells from oxidative damage and prevents ferroptosis. As melanomas are particularly exposed to several sources of oxidative stress, we investigated the biological role of cysteine and glutathione supply by xCT in melanoma. xCT activity was abolished by genetic depletion in the Tyr::CreER; Braf\(^{CA}\); Pten\(^{lox/+}\) melanoma model and by acute cystine withdrawal in melanoma cell lines. Both interventions profoundly impacted melanoma glutathione levels, but they were surprisingly well tolerated by murine melanomas in vivo and by most human melanoma cell lines in vitro. RNA sequencing of human melanoma cells revealed a strong adaptive upregulation of NRF2 and ATF4 pathways, which orchestrated the compensatory upregulation of genes involved in antioxidant defence and de novo cysteine biosynthesis. In addition, the joint activation of ATF4 and NRF2 triggered a phenotypic switch characterized by a reduction of differentiation genes and induction of pro-invasive features, which was also observed after erastin treatment or the inhibition of glutathione synthesis. NRF2 alone was capable of inducing the phenotypic switch in a transient manner. Together, our data show that cystine or glutathione levels regulate the phenotypic plasticity of melanoma cells by elevating ATF4 and NRF2. KW - thiol starvation KW - ATF4 KW - NRF2 KW - melanoma Y1 - 2024 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-350328 VL - 70 ER - TY - JOUR A1 - Jessen, Christina A1 - Kreß, Julia K. C. A1 - Baluapuri, Apoorva A1 - Hufnagel, Anita A1 - Schmitz, Werner A1 - Kneitz, Susanne A1 - Roth, Sabine A1 - Marquardt, André A1 - Appenzeller, Silke A1 - Ade, Casten P. A1 - Glutsch, Valerie A1 - Wobser, Marion A1 - Friedmann-Angeli, José Pedro A1 - Mosteo, Laura A1 - Goding, Colin R. A1 - Schilling, Bastian A1 - Geissinger, Eva A1 - Wolf, Elmar A1 - Meierjohann, Svenja T1 - The transcription factor NRF2 enhances melanoma malignancy by blocking differentiation and inducing COX2 expression JF - Oncogene N2 - The transcription factor NRF2 is the major mediator of oxidative stress responses and is closely connected to therapy resistance in tumors harboring activating mutations in the NRF2 pathway. In melanoma, such mutations are rare, and it is unclear to what extent melanomas rely on NRF2. Here we show that NRF2 suppresses the activity of the melanocyte lineage marker MITF in melanoma, thereby reducing the expression of pigmentation markers. Intriguingly, we furthermore identified NRF2 as key regulator of immune-modulating genes, linking oxidative stress with the induction of cyclooxygenase 2 (COX2) in an ATF4-dependent manner. COX2 is critical for the secretion of prostaglandin E2 and was strongly induced by H\(_2\)O\(_2\) or TNFα only in presence of NRF2. Induction of MITF and depletion of COX2 and PGE2 were also observed in NRF2-deleted melanoma cells in vivo. Furthermore, genes corresponding to the innate immune response such as RSAD2 and IFIH1 were strongly elevated in absence of NRF2 and coincided with immune evasion parameters in human melanoma datasets. Even in vitro, NRF2 activation or prostaglandin E2 supplementation blunted the induction of the innate immune response in melanoma cells. Transcriptome analyses from lung adenocarcinomas indicate that the observed link between NRF2 and the innate immune response is not restricted to melanoma. KW - NRF2 KW - melanoma malignancy KW - COX2 expression Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-235064 SN - 0950-9232 VL - 39 ER - TY - JOUR A1 - Mayer, Alexander E. A1 - Löffler, Mona C. A1 - Loza Valdés, Angel E. A1 - Schmitz, Werner A1 - El-Merahbi, Rabih A1 - Trujillo-Viera, Jonathan A1 - Erk, Manuela A1 - Zhang, Thianzhou A1 - Braun, Ursula A1 - Heikenwalder, Mathias A1 - Leitges, Michael A1 - Schulze, Almut A1 - Sumara, Grzegorz T1 - The kinase PKD3 provides negative feedback on cholesterol and triglyceride synthesis by suppressing insulin signaling JF - Science Signaling N2 - Hepatic activation of protein kinase C (PKC) isoforms by diacylglycerol (DAG) promotes insulin resistance and contributes to the development of type 2 diabetes (T2D). The closely related protein kinase D (PKD) isoforms act as effectors for DAG and PKC. Here, we showed that PKD3 was the predominant PKD isoform expressed in hepatocytes and was activated by lipid overload. PKD3 suppressed the activity of downstream insulin effectors including the kinase AKT and mechanistic target of rapamycin complex 1 and 2 (mTORC1 and mTORC2). Hepatic deletion of PKD3 in mice improved insulin-induced glucose tolerance. However, increased insulin signaling in the absence of PKD3 promoted lipogenesis mediated by SREBP (sterol regulatory element-binding protein) and consequently increased triglyceride and cholesterol content in the livers of PKD3-deficient mice fed a high-fat diet. Conversely, hepatic-specific overexpression of a constitutively active PKD3 mutant suppressed insulin-induced signaling and caused insulin resistance. Our results indicate that PKD3 provides feedback on hepatic lipid production and suppresses insulin signaling. Therefore, manipulation of PKD3 activity could be used to decrease hepatic lipid content or improve hepatic insulin sensitivity. KW - Protein kinase D3 (PKD3) KW - cholesterol KW - diacylglycerol (DAG) KW - liver KW - metabolism Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-250025 ET - accepted manuscript ER - TY - JOUR A1 - Kreß, Julia Katharina Charlotte A1 - Jessen, Christina A1 - Hufnagel, Anita A1 - Schmitz, Werner A1 - Da Xavier Silva, Thamara Nishida A1 - Ferreira Dos Santos, Ancély A1 - Mosteo, Laura A1 - Goding, Colin R. A1 - Friedmann Angeli, José Pedro A1 - Meierjohann, Svenja T1 - The integrated stress response effector ATF4 is an obligatory metabolic activator of NRF2 JF - Cell Reports N2 - Highlights • The integrated stress response leads to a general ATF4-dependent activation of NRF2 • ATF4 causes a CHAC1-dependent GSH depletion, resulting in NRF2 stabilization • An elevation of NRF2 transcript levels fosters this effect • NRF2 supports the ISR/ATF4 pathway by improving cystine and antioxidant supply Summary The redox regulator NRF2 becomes activated upon oxidative and electrophilic stress and orchestrates a response program associated with redox regulation, metabolism, tumor therapy resistance, and immune suppression. Here, we describe an unrecognized link between the integrated stress response (ISR) and NRF2 mediated by the ISR effector ATF4. The ISR is commonly activated after starvation or ER stress and plays a central role in tissue homeostasis and cancer plasticity. ATF4 increases NRF2 transcription and induces the glutathione-degrading enzyme CHAC1, which we now show to be critically important for maintaining NRF2 activation. In-depth analyses reveal that NRF2 supports ATF4-induced cells by increasing cystine uptake via the glutamate-cystine antiporter xCT. In addition, NRF2 upregulates genes mediating thioredoxin usage and regeneration, thus balancing the glutathione decrease. In conclusion, we demonstrate that the NRF2 response serves as second layer of the ISR, an observation highly relevant for the understanding of cellular resilience in health and disease. KW - NRF2 KW - ATF4 KW - integrated stress response KW - CHAC1 KW - melanoma KW - SLC7A11 KW - GSH Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-350312 VL - 42 IS - 7 ER - TY - JOUR A1 - Kasaragod, Prasad A1 - Midekessa, Getnet B. A1 - Sridhar, Shruthi A1 - Schmitz, Werner A1 - Kiema, Tiila-Riikka A1 - Hiltunen, Jukka K. A1 - Wierenga, Rik K. T1 - Structural enzymology comparisons of multifunctional enzyme, type-1 (MFE1): the flexibility of its dehydrogenase part JF - FEBS Open Bio N2 - Multifunctional enzyme, type-1 (MFE1) is a monomeric enzyme with a 2E-enoyl-CoA hydratase and a 3S-hydroxyacyl-CoA dehydrogenase (HAD) active site. Enzyme kinetic data of rat peroxisomal MFE1 show that the catalytic efficiencies for converting the short-chain substrate 2E-butenoyl-CoA into acetoacetyl-CoA are much lower when compared with those of the homologous monofunctional enzymes. The mode of binding of acetoacetyl-CoA (to the hydratase active site) and the very similar mode of binding of NAD\(^+\) and NADH (to the HAD part) are described and compared with those of their monofunctional counterparts. Structural comparisons suggest that the conformational flexibility of the HAD and hydratase parts of MFE1 are correlated. The possible importance of the conformational flexibility of MFE1 for its biocatalytic properties is discussed. KW - biology KW - CoA KW - crotonase KW - dehydrogenase KW - NAD KW - substrate channeling Y1 - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-172732 VL - 7 IS - 12 ER - TY - INPR A1 - Löffler, Mona C. A1 - Mayer, Alexander E. A1 - Trujillo Viera, Jonathan A1 - Loza Valdes, Angel A1 - El-Merahib, Rabih A1 - Ade, Carsten P. A1 - Karwen, Till A1 - Schmitz, Werner A1 - Slotta, Anja A1 - Erk, Manuela A1 - Janaki-Raman, Sudha A1 - Matesanz, Nuria A1 - Torres, Jorge L. A1 - Marcos, Miguel A1 - Sabio, Guadalupe A1 - Eilers, Martin A1 - Schulze, Almut A1 - Sumara, Grzegorz T1 - Protein kinase D1 deletion in adipocytes enhances energy dissipation and protects against adiposity T2 - The EMBO Journal N2 - Nutrient overload in combination with decreased energy dissipation promotes obesity and diabetes. Obesity results in a hormonal imbalance, which among others, activates G-protein coupled receptors utilizing diacylglycerol (DAG) as secondary messenger. Protein kinase D1 (PKD1) is a DAG effector which integrates multiple nutritional and hormonal inputs, but its physiological role in adipocytes is unknown. Here, we show that PKD1 promotes lipogenesis and suppresses mitochondrial fragmentation, biogenesis, respiration, and energy dissipation in an AMP-activated protein kinase (AMPK)-dependent manner. Moreover, mice lacking PKD1 in adipocytes are resistant to diet-induced obesity due to elevated energy expenditure. Beiging of adipocytes promotes energy expenditure and counteracts obesity. Consistently, deletion of PKD1 promotes expression of the β3-adrenergic receptor (ADRB3) in a CCAAT/enhancerbinding protein (C/EBP)-α and δ-dependent manner, which leads to the elevated expression of beige markers in adipocytes and subcutaneous adipose tissue. Finally, deletion of PKD1 in adipocytes improves insulin sensitivity and ameliorates liver steatosis. Thus, loss of PKD1 in adipocytes increases energy dissipation by several complementary mechanisms and might represent an attractive strategy to treat obesity and its related complications. KW - AMP-activated protein kinase (AMPK) KW - Beige adipocytes KW - β3 adrenergic receptor (ADRB3) KW - C/EBP KW - Protein kinase D1 (PKD1) Y1 - 2018 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-176093 ER - TY - JOUR A1 - Bohnert, Simone A1 - Wirth, Christoph A1 - Schmitz, Werner A1 - Trella, Stefanie A1 - Monoranu, Camelia-Maria A1 - Ondruschka, Benjamin A1 - Bohnert, Michael T1 - Myelin basic protein and neurofilament H in postmortem cerebrospinal fluid as surrogate markers of fatal traumatic brain injury JF - International Journal of Legal Medicine N2 - The aim of this study was to investigate if the biomarkers myelin basic protein (MBP) and neurofilament-H (NF-H) yielded informative value in forensic diagnostics when examining cadaveric cerebrospinal fluid (CSF) biochemically via an enzyme-linked immunosorbent assay (ELISA) and comparing the corresponding brain tissue in fatal traumatic brain injury (TBI) autopsy cases by immunocytochemistry versus immunohistochemistry. In 21 trauma and 19 control cases, CSF was collected semi-sterile after suboccipital puncture and brain specimens after preparation. The CSF MBP (p = 0.006) and NF-H (p = 0.0002) levels after TBI were significantly higher than those in cardiovascular controls. Immunohistochemical staining against MBP and against NF-H was performed on cortical and subcortical samples from also biochemically investigated cases (5 TBI cases/5 controls). Compared to the controls, the TBI cases showed a visually reduced staining reaction against MBP or repeatedly ruptured neurofilaments against NF-H. Immunocytochemical tests showed MBP-positive phagocytizing macrophages in CSF with a survival time of > 24 h. In addition, numerous TMEM119-positive microglia could be detected with different degrees of staining intensity in the CSF of trauma cases. As a result, we were able to document that elevated levels of MBP and NF-H in the CSF should be considered as useful neuroinjury biomarkers of traumatic brain injury. KW - biofluid KW - CSF KW - cerebrospinal fluid KW - forensic neuropathology KW - forensic neurotraumatology KW - biomarker Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-266929 SN - 1437-1596 VL - 135 IS - 4 ER - TY - JOUR A1 - Wu, Hao A1 - Zhao, Xiufeng A1 - Hochrein, Sophia M. A1 - Eckstein, Miriam A1 - Gubert, Gabriela F. A1 - Knöpper, Konrad A1 - Mansilla, Ana Maria A1 - Öner, Arman A1 - Doucet-Ladevèze, Remi A1 - Schmitz, Werner A1 - Ghesquière, Bart A1 - Theurich, Sebastian A1 - Dudek, Jan A1 - Gasteiger, Georg A1 - Zernecke, Alma A1 - Kobold, Sebastian A1 - Kastenmüller, Wolfgang A1 - Vaeth, Martin T1 - Mitochondrial dysfunction promotes the transition of precursor to terminally exhausted T cells through HIF-1α-mediated glycolytic reprogramming JF - Nature Communications N2 - T cell exhaustion is a hallmark of cancer and persistent infections, marked by inhibitory receptor upregulation, diminished cytokine secretion, and impaired cytolytic activity. Terminally exhausted T cells are steadily replenished by a precursor population (Tpex), but the metabolic principles governing Tpex maintenance and the regulatory circuits that control their exhaustion remain incompletely understood. Using a combination of gene-deficient mice, single-cell transcriptomics, and metabolomic analyses, we show that mitochondrial insufficiency is a cell-intrinsic trigger that initiates the functional exhaustion of T cells. At the molecular level, we find that mitochondrial dysfunction causes redox stress, which inhibits the proteasomal degradation of hypoxia-inducible factor 1α (HIF-1α) and promotes the transcriptional and metabolic reprogramming of Tpex cells into terminally exhausted T cells. Our findings also bear clinical significance, as metabolic engineering of chimeric antigen receptor (CAR) T cells is a promising strategy to enhance the stemness and functionality of Tpex cells for cancer immunotherapy. KW - cytotoxic T cells KW - infection KW - lymphocyte differentiation KW - translational research Y1 - 2023 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-358052 VL - 14 ER - TY - JOUR A1 - Bohnert, Simone A1 - Reinert, Christoph A1 - Trella, Stefanie A1 - Schmitz, Werner A1 - Ondruschka, Benjamin A1 - Bohnert, Michael T1 - Metabolomics in postmortem cerebrospinal fluid diagnostics: a state-of-the-art method to interpret central nervous system–related pathological processes JF - International Journal of Legal Medicine N2 - In the last few years, quantitative analysis of metabolites in body fluids using LC/MS has become an established method in laboratory medicine and toxicology. By preparing metabolite profiles in biological specimens, we are able to understand pathophysiological mechanisms at the biochemical and thus the functional level. An innovative investigative method, which has not yet been used widely in the forensic context, is to use the clinical application of metabolomics. In a metabolomic analysis of 41 samples of postmortem cerebrospinal fluid (CSF) samples divided into cohorts of four different causes of death, namely, cardiovascular fatalities, isoIated torso trauma, traumatic brain injury, and multi-organ failure, we were able to identify relevant differences in the metabolite profile between these individual groups. According to this preliminary assessment, we assume that information on biochemical processes is not gained by differences in the concentration of individual metabolites in CSF, but by a combination of differently distributed metabolites forming the perspective of a new generation of biomarkers for diagnosing (fatal) TBI and associated neuropathological changes in the CNS using CSF samples. KW - CSF KW - cerebrospinal fluid KW - forensic neuropathology KW - forensic neurotraumatology KW - biomarker KW - metabolomics Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-235724 SN - 0937-9827 VL - 135 ER - TY - JOUR A1 - Schmitz, Werner A1 - Koderer, Corinna A1 - El-Mesery, Mohamed A1 - Gobik, Sebastian A1 - Sampers, Rene A1 - Straub, Anton A1 - Kübler, Alexander Christian A1 - Seher, Axel T1 - Metabolic fingerprinting of murine L929 fibroblasts as a cell-based tumour suppressor model system for methionine restriction JF - International Journal of Molecular Sciences N2 - Since Otto Warburg reported in 1924 that cancer cells address their increased energy requirement through a massive intake of glucose, the cellular energy level has offered a therapeutic anticancer strategy. Methionine restriction (MetR) is one of the most effective approaches for inducing low-energy metabolism (LEM) due to the central position in metabolism of this amino acid. However, no simple in vitro system for the rapid analysis of MetR is currently available, and this study establishes the murine cell line L929 as such a model system. L929 cells react rapidly and efficiently to MetR, and the analysis of more than 150 different metabolites belonging to different classes (amino acids, urea and tricarboxylic acid cycle (TCA) cycles, carbohydrates, etc.) by liquid chromatography/mass spectrometry (LC/MS) defines a metabolic fingerprint and enables the identification of specific metabolites representing normal or MetR conditions. The system facilitates the rapid and efficient testing of potential cancer therapeutic metabolic targets. To date, MS studies of MetR have been performed using organisms and yeast, and the current LC/MS analysis of the intra- and extracellular metabolites in the murine cell line L929 over a period of 5 days thus provides new insights into the effects of MetR at the cellular metabolic level. KW - methionine restriction KW - caloric restriction KW - mass spectrometry KW - LC/MS KW - liquid chromatography/mass spectrometry KW - metabolism KW - L929 KW - amino acid Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-259198 SN - 1422-0067 VL - 22 IS - 6 ER -