@article{BrodehlPourHakimiStanasiuketal.2019, author = {Brodehl, Andreas and Pour Hakimi, Seyed Ahmad and Stanasiuk, Caroline and Ratnavadivel, Sandra and Hendig, Doris and Gaertner, Anna and Gerull, Brenda and Gummert, Jan and Paluszkiewicz, Lech and Milting, Hendrik}, title = {Restrictive cardiomyopathy is caused by a novel homozygous desmin (DES) mutation p.Y122H leading to a severe filament assembly defect}, series = {Genes}, volume = {10}, journal = {Genes}, number = {11}, issn = {2073-4425}, doi = {10.3390/genes10110918}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-193121}, year = {2019}, abstract = {Here, we present a small Iranian family, where the index patient received a diagnosis of restrictive cardiomyopathy (RCM) in combination with atrioventricular (AV) block. Genetic analysis revealed a novel homozygous missense mutation in the DES gene (c.364T > C; p.Y122H), which is absent in human population databases. The mutation is localized in the highly conserved coil-1 desmin subdomain. In silico, prediction tools indicate a deleterious effect of the desmin (DES) mutation p.Y122H. Consequently, we generated an expression plasmid encoding the mutant and wildtype desmin formed, and analyzed the filament formation in vitro in cardiomyocytes derived from induced pluripotent stem cells and HT-1080 cells. Confocal microscopy revealed a severe filament assembly defect of mutant desmin supporting the pathogenicity of the DES mutation, p.Y122H, whereas the wildtype desmin formed regular intermediate filaments. According to the guidelines of the American College of Medical Genetics and Genomics, we classified this mutation, therefore, as a novel pathogenic mutation. Our report could point to a recessive inheritance of the DES mutation, p.Y122H, which is important for the genetic counseling of similar families with restrictive cardiomyopathy caused by DES mutations.}, language = {en} } @article{KuehnischHerbstAl‐Wakeel‐Marquardetal.2019, author = {K{\"u}hnisch, Jirko and Herbst, Christopher and Al-Wakeel-Marquard, Nadya and Dartsch, Josephine and Holtgrewe, Manuel and Baban, Anwar and Mearini, Giulia and Hardt, Juliane and Kolokotronis, Konstantinos and Gerull, Brenda and Carrier, Lucie and Beule, Dieter and Schubert, Stephan and Messroghli, Daniel and Degener, Franziska and Berger, Felix and Klaassen, Sabine}, title = {Targeted panel sequencing in pediatric primary cardiomyopathy supports a critical role of TNNI3}, series = {Clinical Genetics}, volume = {96}, journal = {Clinical Genetics}, number = {6}, doi = {10.1111/cge.13645}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-213958}, pages = {549 -- 559}, year = {2019}, abstract = {The underlying genetic mechanisms and early pathological events of children with primary cardiomyopathy (CMP) are insufficiently characterized. In this study, we aimed to characterize the mutational spectrum of primary CMP in a large cohort of patients ≤18 years referred to a tertiary center. Eighty unrelated index patients with pediatric primary CMP underwent genetic testing with a panel-based next-generation sequencing approach of 89 genes. At least one pathogenic or probably pathogenic variant was identified in 30/80 (38\%) index patients. In all CMP subgroups, patients carried most frequently variants of interest in sarcomere genes suggesting them as a major contributor in pediatric primary CMP. In MYH7, MYBPC3, and TNNI3, we identified 18 pathogenic/probably pathogenic variants (MYH7 n = 7, MYBPC3 n = 6, TNNI3 n = 5, including one homozygous (TNNI3 c.24+2T>A) truncating variant. Protein and transcript level analysis on heart biopsies from individuals with homozygous mutation of TNNI3 revealed that the TNNI3 protein is absent and associated with upregulation of the fetal isoform TNNI1. The present study further supports the clinical importance of sarcomeric mutation—not only in adult—but also in pediatric primary CMP. TNNI3 is the third most important disease gene in this cohort and complete loss of TNNI3 leads to severe pediatric CMP.}, language = {en} } @article{SeidlmayerMagesBerbneretal.2019, author = {Seidlmayer, Lea K. and Mages, Christine and Berbner, Annette and Eder-Negrin, Petra and Arias-Loza, Paula Anahi and Kaspar, Mathias and Song, Moshi and Dorn, Gerald W. and Kohlhaas, Michael and Frantz, Stefan and Maack, Christoph and Gerull, Brenda and Dedkova, Elena N.}, title = {Mitofusin 2 is essential for IP3-mediated SR/Mitochondria metabolic feedback in ventricular myocytes}, series = {Frontiers in Physiology}, volume = {10}, journal = {Frontiers in Physiology}, number = {733}, issn = {1664-042X}, doi = {10.3389/fphys.2019.00733}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-199141}, year = {2019}, abstract = {Aim: Endothelin-1 (ET-1) and angiotensin II (Ang II) are multifunctional peptide hormones that regulate the function of the cardiovascular and renal systems. Both hormones increase the intracellular production of inositol-1,4,5-trisphosphate (IP\(_3\)) by activating their membrane-bound receptors. We have previously demonstrated that IP\(_3\)-mediated sarcoplasmic reticulum (SR) Ca\(^{2+}\) release results in mitochondrial Ca\(^{2+}\) uptake and activation of ATP production. In this study, we tested the hypothesis that intact SR/mitochondria microdomains are required for metabolic IP\(_3\)-mediated SR/mitochondrial feedback in ventricular myocytes. Methods: As a model for disrupted mitochondrial/SR microdomains, cardio-specific tamoxifen-inducible mitofusin 2 (Mfn2) knock out (KO) mice were used. Mitochondrial Ca\(^{2+}\) uptake, membrane potential, redox state, and ATP generation were monitored in freshly isolated ventricular myocytes from Mfn2 KO mice and their control wild-type (WT) littermates. Results: Stimulation of ET-1 receptors in healthy control myocytes increases mitochondrial Ca\(^{2+}\) uptake, maintains mitochondrial membrane potential and redox balance leading to the enhanced ATP generation. Mitochondrial Ca\(^{2+}\) uptake upon ET-1 stimulation was significantly higher in interfibrillar (IFM) and perinuclear (PNM) mitochondria compared to subsarcolemmal mitochondria (SSM) in WT myocytes. Mfn2 KO completely abolished mitochondrial Ca\(^{2+}\) uptake in IFM and PNM mitochondria but not in SSM. However, mitochondrial Ca2+ uptake induced by beta-adrenergic receptors activation with isoproterenol (ISO) was highest in SSM, intermediate in IFM, and smallest in PNM regions. Furthermore, Mfn2 KO did not affect ISO-induced mitochondrial Ca\(^{2+}\) uptake in SSM and IFM mitochondria; however, enhanced mitochondrial Ca\(^{2+}\) uptake in PNM. In contrast to ET-1, ISO induced a decrease in ATP levels in WT myocytes. Mfn2 KO abolished ATP generation upon ET-1 stimulation but increased ATP levels upon ISO application with highest levels observed in PNM regions. Conclusion: When the physical link between SR and mitochondria by Mfn2 was disrupted, the SR/mitochondrial metabolic feedback mechanism was impaired resulting in the inability of the IP\(_3\)-mediated SR Ca\(^{2+}\) release to induce ATP production in ventricular myocytes from Mfn2 KO mice. Furthermore, we revealed the difference in Mfn2-mediated SR-mitochondrial communication depending on mitochondrial location and type of communication (IP\(_3\)R-mRyR1 vs. ryanodine receptor type 2-mitochondrial calcium uniporter).}, language = {en} }