@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{GerullBrodehl2020, author = {Gerull, Brenda and Brodehl, Andreas}, title = {Genetic Animal Models for Arrhythmogenic Cardiomyopathy}, series = {Frontiers in Physiology}, volume = {11}, journal = {Frontiers in Physiology}, number = {264}, issn = {1664-042X}, doi = {10.3389/fphys.2020.00624}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-206903}, year = {2020}, abstract = {Arrhythmogenic cardiomyopathy has been clinically defined since the 1980s and causes right or biventricular cardiomyopathy associated with ventricular arrhythmia. Although it is a rare cardiac disease, it is responsible for a significant proportion of sudden cardiac deaths, especially in athletes. The majority of patients with arrhythmogenic cardiomyopathy carry one or more genetic variants in desmosomal genes. In the 1990s, several knockout mouse models of genes encoding for desmosomal proteins involved in cell-cell adhesion revealed for the first time embryonic lethality due to cardiac defects. Influenced by these initial discoveries in mice, arrhythmogenic cardiomyopathy received an increasing interest in human cardiovascular genetics, leading to the discovery of mutations initially in desmosomal genes and later on in more than 25 different genes. Of note, even in the clinic, routine genetic diagnostics are important for risk prediction of patients and their relatives with arrhythmogenic cardiomyopathy. Based on improvements in genetic animal engineering, different transgenic, knock-in, or cardiac-specific knockout animal models for desmosomal and nondesmosomal proteins have been generated, leading to important discoveries in this field. Here, we present an overview about the existing animal models of arrhythmogenic cardiomyopathy with a focus on the underlying pathomechanism and its importance for understanding of this disease. Prospectively, novel mechanistic insights gained from the whole animal, organ, tissue, cellular, and molecular levels will lead to the development of efficient personalized therapies for treatment of arrhythmogenic cardiomyopathy.}, 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} }