@article{ShemerMekiesBenJehudaetal.2021, author = {Shemer, Yuval and Mekies, Lucy N. and Ben Jehuda, Ronen and Baskin, Polina and Shulman, Rita and Eisen, Binyamin and Regev, Danielle and Arbustini, Eloisa and Gerull, Brenda and Gherghiceanu, Mihaela and Gottlieb, Eyal and Arad, Michael and Binah, Ofer}, title = {Investigating LMNA-related dilated cardiomyopathy using human induced Pluripotent Stem Cell-derived cardiomyocytes}, series = {International Journal of Molecular Sciences}, volume = {22}, journal = {International Journal of Molecular Sciences}, number = {15}, issn = {1422-0067}, doi = {10.3390/ijms22157874}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-285673}, year = {2021}, abstract = {LMNA-related dilated cardiomyopathy is an inherited heart disease caused by mutations in the LMNA gene encoding for lamin A/C. The disease is characterized by left ventricular enlargement and impaired systolic function associated with conduction defects and ventricular arrhythmias. We hypothesized that LMNA-mutated patients' induced Pluripotent Stem Cell-derived cardiomyocytes (iPSC-CMs) display electrophysiological abnormalities, thus constituting a suitable tool for deciphering the arrhythmogenic mechanisms of the disease, and possibly for developing novel therapeutic modalities. iPSC-CMs were generated from two related patients (father and son) carrying the same E342K mutation in the LMNA gene. Compared to control iPSC-CMs, LMNA-mutated iPSC-CMs exhibited the following electrophysiological abnormalities: (1) decreased spontaneous action potential beat rate and decreased pacemaker current (I\(_f\)) density; (2) prolonged action potential duration and increased L-type Ca\(^{2+}\) current (I\(_{Ca,L}\)) density; (3) delayed afterdepolarizations (DADs), arrhythmias and increased beat rate variability; (4) DADs, arrhythmias and cessation of spontaneous firing in response to β-adrenergic stimulation and rapid pacing. Additionally, compared to healthy control, LMNA-mutated iPSC-CMs displayed nuclear morphological irregularities and gene expression alterations. Notably, KB-R7943, a selective inhibitor of the reverse-mode of the Na\(^+\)/Ca\(^{2+}\) exchanger, blocked the DADs in LMNA-mutated iPSC-CMs. Our findings demonstrate cellular electrophysiological mechanisms underlying the arrhythmias in LMNA-related dilated cardiomyopathy.}, language = {en} } @article{GerullBrodehl2021, author = {Gerull, Brenda and Brodehl, Andreas}, title = {Insights Into Genetics and Pathophysiology of Arrhythmogenic Cardiomyopathy}, series = {Current Heart Failure Reports}, volume = {18}, journal = {Current Heart Failure Reports}, number = {6}, issn = {1546-9549}, doi = {10.1007/s11897-021-00532-z}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-269916}, pages = {378-390}, year = {2021}, abstract = {Purpose of Review Arrhythmogenic cardiomyopathy (ACM) is a genetic disease characterized by life-threatening ventricular arrhythmias and sudden cardiac death (SCD) in apparently healthy young adults. Mutations in genes encoding for cellular junctions can be found in about half of the patients. However, disease onset and severity, risk of arrhythmias, and outcome are highly variable and drug-targeted treatment is currently unavailable. Recent Findings This review focuses on advances in clinical risk stratification, genetic etiology, and pathophysiological concepts. The desmosome is the central part of the disease, but other intercalated disc and associated structural proteins not only broaden the genetic spectrum but also provide novel molecular and cellular insights into the pathogenesis of ACM. Signaling pathways and the role of inflammation will be discussed and targets for novel therapeutic approaches outlined. Summary Genetic discoveries and experimental-driven preclinical research contributed significantly to the understanding of ACM towards mutation- and pathway-specific personalized medicine.}, language = {en} } @article{BenzMerkelOffneretal.2013, author = {Benz, Peter M. and Merkel, Carla J. and Offner, Kristin and Abeßer, Marco and Ullrich, Melanie and Fischer, Tobias and Bayer, Barbara and Wagner, Helga and Gambaryan, Stepan and Ursitti, Jeanine A. and Adham, Ibrahim M. and Linke, Wolfgang A. and Feller, Stephan M. and Fleming, Ingrid and Renn{\´e}, Thomas and Frantz, Stefan and Unger, Andreas and Schuh, Kai}, title = {Mena/VASP and alphaII-Spectrin complexes regulate cytoplasmic actin networks in cardiomyocytes and protect from conduction abnormalities and dilated cardiomyopathy}, series = {Cell Communication and Signaling}, volume = {11}, journal = {Cell Communication and Signaling}, number = {56}, doi = {10.1186/1478-811X-11-56}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-128760}, year = {2013}, abstract = {Background: In the heart, cytoplasmic actin networks are thought to have important roles in mechanical support, myofibrillogenesis, and ion channel function. However, subcellular localization of cytoplasmic actin isoforms and proteins involved in the modulation of the cytoplasmic actin networks are elusive. Mena and VASP are important regulators of actin dynamics. Due to the lethal phenotype of mice with combined deficiency in Mena and VASP, however, distinct cardiac roles of the proteins remain speculative. In the present study, we analyzed the physiological functions of Mena and VASP in the heart and also investigated the role of the proteins in the organization of cytoplasmic actin networks. Results: We generated a mouse model, which simultaneously lacks Mena and VASP in the heart. Mena/VASP double-deficiency induced dilated cardiomyopathy and conduction abnormalities. In wild-type mice, Mena and VASP specifically interacted with a distinct αII-Spectrin splice variant (SH3i), which is in cardiomyocytes exclusively localized at Z- and intercalated discs. At Z- and intercalated discs, Mena and β-actin localized to the edges of the sarcomeres, where the thin filaments are anchored. In Mena/VASP double-deficient mice, β-actin networks were disrupted and the integrity of Z- and intercalated discs was markedly impaired. Conclusions: Together, our data suggest that Mena, VASP, and αII-Spectrin assemble cardiac multi-protein complexes, which regulate cytoplasmic actin networks. Conversely, Mena/VASP deficiency results in disrupted β-actin assembly, Z- and intercalated disc malformation, and induces dilated cardiomyopathy and conduction abnormalities.}, language = {en} }