@article{EberlRebsHoppeetal.2024, author = {Eberl, Hanna and Rebs, Sabine and Hoppe, Stefanie and Sedaghat-Hamedani, Farbod and Kayvanpour, Elham and Meder, Benjamin and Streckfuss-B{\"o}meke, Katrin}, title = {Generation of an RBM20-mutation-associated left-ventricular non-compaction cardiomyopathy iPSC line (UMGi255-A) into a DCM genetic background to investigate monogenetic cardiomyopathies}, series = {Stem Cell Research}, volume = {74}, journal = {Stem Cell Research}, issn = {1873-5061}, doi = {10.1016/j.scr.2023.103290}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-350565}, year = {2024}, abstract = {RBM20 mutations account for 3 \% of genetic cardiomypathies and manifest with high penetrance and arrhythmogenic effects. Numerous mutations in the conserved RS domain have been described as causing dilated cardiomyopathy (DCM), whereas a particular mutation (p.R634L) drives development of a different cardiac phenotype: left-ventricular non-compaction cardiomyopathy. We generated a mutation-induced pluripotent stem cell (iPSC) line in which the RBM20-LVNC mutation p.R634L was introduced into a DCM patient line with rescued RBM20-p.R634W mutation. These DCM-634L-iPSC can be differentiated into functional cardiomyocytes to test whether this RBM20 mutation induces development of the LVNC phenotype within the genetic context of a DCM patient.}, language = {en} } @article{JanzWalzCirnuetal.2024, author = {Janz, Anna and Walz, Katharina and Cirnu, Alexandra and Surjanto, Jessica and Urlaub, Daniela and Leskien, Miriam and Kohlhaas, Michael and Nickel, Alexander and Brand, Theresa and Nose, Naoko and W{\"o}rsd{\"o}rfer, Philipp and Wagner, Nicole and Higuchi, Takahiro and Maack, Christoph and Dudek, Jan and Lorenz, Kristina and Klopocki, Eva and Erg{\"u}n, S{\"u}leyman and Duff, Henry J. and Gerull, Brenda}, title = {Mutations in DNAJC19 cause altered mitochondrial structure and increased mitochondrial respiration in human iPSC-derived cardiomyocytes}, series = {Molecular Metabolism}, volume = {79}, journal = {Molecular Metabolism}, issn = {2212-8778}, doi = {10.1016/j.molmet.2023.101859}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-350393}, year = {2024}, abstract = {Highlights • Loss of DNAJC19's DnaJ domain disrupts cardiac mitochondrial structure, leading to abnormal cristae formation in iPSC-CMs. • Impaired mitochondrial structures lead to an increased mitochondrial respiration, ROS and an elevated membrane potential. • Mutant iPSC-CMs show sarcomere dysfunction and a trend to more arrhythmias, resembling DCMA-associated cardiomyopathy. Background Dilated cardiomyopathy with ataxia (DCMA) is an autosomal recessive disorder arising from truncating mutations in DNAJC19, which encodes an inner mitochondrial membrane protein. Clinical features include an early onset, often life-threatening, cardiomyopathy associated with other metabolic features. Here, we aim to understand the metabolic and pathophysiological mechanisms of mutant DNAJC19 for the development of cardiomyopathy. Methods We generated induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) of two affected siblings with DCMA and a gene-edited truncation variant (tv) of DNAJC19 which all lack the conserved DnaJ interaction domain. The mutant iPSC-CMs and their respective control cells were subjected to various analyses, including assessments of morphology, metabolic function, and physiological consequences such as Ca\(^{2+}\) kinetics, contractility, and arrhythmic potential. Validation of respiration analysis was done in a gene-edited HeLa cell line (DNAJC19tv\(_{HeLa}\)). Results Structural analyses revealed mitochondrial fragmentation and abnormal cristae formation associated with an overall reduced mitochondrial protein expression in mutant iPSC-CMs. Morphological alterations were associated with higher oxygen consumption rates (OCRs) in all three mutant iPSC-CMs, indicating higher electron transport chain activity to meet cellular ATP demands. Additionally, increased extracellular acidification rates suggested an increase in overall metabolic flux, while radioactive tracer uptake studies revealed decreased fatty acid uptake and utilization of glucose. Mutant iPSC-CMs also showed increased reactive oxygen species (ROS) and an elevated mitochondrial membrane potential. Increased mitochondrial respiration with pyruvate and malate as substrates was observed in mutant DNAJC19tv HeLa cells in addition to an upregulation of respiratory chain complexes, while cellular ATP-levels remain the same. Moreover, mitochondrial alterations were associated with increased beating frequencies, elevated diastolic Ca\(^{2+}\) concentrations, reduced sarcomere shortening and an increased beat-to-beat rate variability in mutant cell lines in response to β-adrenergic stimulation. Conclusions Loss of the DnaJ domain disturbs cardiac mitochondrial structure with abnormal cristae formation and leads to mitochondrial dysfunction, suggesting that DNAJC19 plays an essential role in mitochondrial morphogenesis and biogenesis. Moreover, increased mitochondrial respiration, altered substrate utilization, increased ROS production and abnormal Ca\(^{2+}\) kinetics provide insights into the pathogenesis of DCMA-related cardiomyopathy.}, language = {en} } @article{NishidaXavierdaSilvaSchulteNunesAlvesetal.2023, author = {Nishida Xavier da Silva, Thamara and Schulte, Clemens and Nunes Alves, Ariane and Maric, Hans Michael and Friedmann Angeli, Jos{\´e} Pedro}, title = {Molecular characterization of AIFM2/FSP1 inhibition by iFSP1-like molecules}, series = {Cell Death \& Disease}, volume = {14}, journal = {Cell Death \& Disease}, doi = {10.1038/s41419-023-05787-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-357943}, year = {2023}, abstract = {Ferroptosis is a form of cell death characterized by phospholipid peroxidation, where numerous studies have suggested that the induction of ferroptosis is a therapeutic strategy to target therapy refractory cancer entities. Ferroptosis suppressor protein 1 (FSP1), an NAD(P)H-ubiquinone reductase, is a key determinant of ferroptosis vulnerability, and its pharmacological inhibition was shown to strongly sensitize cancer cells to ferroptosis. A first generation of FSP1 inhibitors, exemplified by the small molecule iFSP1, has been reported; however, the molecular mechanisms underlying inhibition have not been characterized in detail. In this study, we explore the species-specific inhibition of iFSP1 on the human isoform to gain insights into its mechanism of action. Using a combination of cellular, biochemical, and computational methods, we establish a critical contribution of a species-specific aromatic architecture that is essential for target engagement. The results described here provide valuable insights for the rational development of second-generation FSP1 inhibitors combined with a tracer for screening the druggable pocket. In addition, we pose a cautionary notice for using iFSP1 in animal models, specifically murine models.}, language = {en} } @article{KoernerMeyerMarincolaetal.2023, author = {K{\"o}rner, Maria and Meyer, Susanne R. and Marincola, Gabriella and Kern, Maximilian J. and Grimm, Clemens and Schuelein-Voelk, Christina and Fischer, Utz and Hofmann, Kay and Buchberger, Alexander}, title = {The FAM104 proteins VCF1/2 promote the nuclear localization of p97/VCP}, series = {eLife}, volume = {12}, journal = {eLife}, doi = {10.7554/eLife.92409}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-350222}, year = {2023}, abstract = {The ATPase p97 (also known as VCP, Cdc48) has crucial functions in a variety of important cellular processes such as protein quality control, organellar homeostasis, and DNA damage repair, and its de-regulation is linked to neuromuscular diseases and cancer. p97 is tightly controlled by numerous regulatory cofactors, but the full range and function of the p97-cofactor network is unknown. Here, we identify the hitherto uncharacterized FAM104 proteins as a conserved family of p97 interactors. The two human family members VCP nuclear cofactor family member 1 and 2 (VCF1/2) bind p97 directly via a novel, alpha-helical motif and associate with p97-UFD1-NPL4 and p97-UBXN2B complexes in cells. VCF1/2 localize to the nucleus and promote the nuclear import of p97. Loss of VCF1/2 results in reduced nuclear p97 levels, slow growth, and hypersensitivity to chemical inhibition of p97 in the absence and presence of DNA damage, suggesting that FAM104 proteins are critical regulators of nuclear p97 functions.}, language = {en} } @article{HurdGruebelWojciechowskietal.2021, author = {Hurd, Paul J. and Gr{\"u}bel, Kornelia and Wojciechowski, Marek and Maleszka, Ryszard and R{\"o}ssler, Wolfgang}, title = {Novel structure in the nuclei of honey bee brain neurons revealed by immunostaining}, series = {Scientific Reports}, volume = {11}, journal = {Scientific Reports}, doi = {10.1038/s41598-021-86078-5}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-260059}, pages = {6852}, year = {2021}, abstract = {In the course of a screen designed to produce antibodies (ABs) with affinity to proteins in the honey bee brain we found an interesting AB that detects a highly specific epitope predominantly in the nuclei of Kenyon cells (KCs). The observed staining pattern is unique, and its unfamiliarity indicates a novel previously unseen nuclear structure that does not colocalize with the cytoskeletal protein f-actin. A single rod-like assembly, 3.7-4.1 mu m long, is present in each nucleus of KCs in adult brains of worker bees and drones with the strongest immuno-labelling found in foraging bees. In brains of young queens, the labelling is more sporadic, and the rod-like structure appears to be shorter (similar to 2.1 mu m). No immunostaining is detectable in worker larvae. In pupal stage 5 during a peak of brain development only some occasional staining was identified. Although the cellular function of this unexpected structure has not been determined, the unusual distinctiveness of the revealed pattern suggests an unknown and potentially important protein assembly. One possibility is that this nuclear assembly is part of the KCs plasticity underlying the brain maturation in adult honey bees. Because no labelling with this AB is detectable in brains of the fly Drosophila melanogaster and the ant Camponotus floridanus, we tentatively named this antibody AmBNSab (Apis mellifera Brain Neurons Specific antibody). Here we report our results to make them accessible to a broader community and invite further research to unravel the biological role of this curious nuclear structure in the honey bee central brain.}, language = {en} } @article{LorenzinBenaryBaluapurietal.2016, author = {Lorenzin, Francesca and Benary, Uwe and Baluapuri, Apoorva and Walz, Susanne and Jung, Lisa Anna and von Eyss, Bj{\"o}rn and Kisker, Caroline and Wolf, Jana and Eilers, Martin and Wolf, Elmar}, title = {Different promoter affinities account for specificity in MYC-dependent gene regulation}, series = {eLife}, volume = {5}, journal = {eLife}, doi = {10.7554/eLife.15161}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-162913}, pages = {e15161}, year = {2016}, abstract = {Enhanced expression of the MYC transcription factor is observed in the majority of tumors. Two seemingly conflicting models have been proposed for its function: one proposes that MYC enhances expression of all genes, while the other model suggests gene-specific regulation. Here, we have explored the hypothesis that specific gene expression profiles arise since promoters differ in affinity for MYC and high-affinity promoters are fully occupied by physiological levels of MYC. We determined cellular MYC levels and used RNA- and ChIP-sequencing to correlate promoter occupancy with gene expression at different concentrations of MYC. Mathematical modeling showed that binding affinities for interactions of MYC with DNA and with core promoter-bound factors, such as WDR5, are sufficient to explain promoter occupancies observed in vivo. Importantly, promoter affinity stratifies different biological processes that are regulated by MYC, explaining why tumor-specific MYC levels induce specific gene expression programs and alter defined biological properties of cells.}, language = {en} } @article{BatramJonesJanzenetal.2014, author = {Batram, Christopher and Jones, Nivola G. and Janzen, Christian J. and Markert, Sebastian M. and Engstler, Markus}, title = {Expression site attenuation mechanistically links antigenic variation and development in Trypanosoma brucei}, series = {eLife}, volume = {3}, journal = {eLife}, number = {e02324}, issn = {2050-084X}, doi = {10.7554/eLife.02324}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-119727}, year = {2014}, abstract = {We have discovered a new mechanism of monoallelic gene expression that links antigenic variation, cell cycle, and development in the model parasite Trypanosoma brucei. African trypanosomes possess hundreds of variant surface glycoprotein (VSG) genes, but only one is expressed from a telomeric expression site (ES) at any given time. We found that the expression of a second VSG alone is sufficient to silence the active VSG gene and directionally attenuate the ES by disruptor of telomeric silencing-1B (DOT1B)-mediated histone methylation. Three conserved expression-site-associated genes (ESAGs) appear to serve as signal for ES attenuation. Their depletion causes G1-phase dormancy and reversible initiation of the slender-to-stumpy differentiation pathway. ES-attenuated slender bloodstream trypanosomes gain full developmental competence for transformation to the tsetse fly stage. This surprising connection between antigenic variation and developmental progression provides an unexpected point of attack against the deadly sleeping sickness.}, language = {en} }