@article{ZinkSeewaldRohrbachetal.2022, author = {Zink, Miriam and Seewald, Anne and Rohrbach, Mareike and Brodehl, Andreas and Liedtke, Daniel and Williams, Tatjana and Childs, Sarah J. and Gerull, Brenda}, title = {Altered expression of TMEM43 causes abnormal cardiac structure and function in zebrafish}, series = {International Journal of Molecular Sciences}, volume = {23}, journal = {International Journal of Molecular Sciences}, number = {17}, issn = {1422-0067}, doi = {10.3390/ijms23179530}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-286025}, year = {2022}, abstract = {Arrhythmogenic cardiomyopathy (ACM) is an inherited heart muscle disease caused by heterozygous missense mutations within the gene encoding for the nuclear envelope protein transmembrane protein 43 (TMEM43). The disease is characterized by myocyte loss and fibro-fatty replacement, leading to life-threatening ventricular arrhythmias and sudden cardiac death. However, the role of TMEM43 in the pathogenesis of ACM remains poorly understood. In this study, we generated cardiomyocyte-restricted transgenic zebrafish lines that overexpress eGFP-linked full-length human wild-type (WT) TMEM43 and two genetic variants (c.1073C>T, p.S358L; c.332C>T, p.P111L) using the Tol2-system. Overexpression of WT and p.P111L-mutant TMEM43 was associated with transcriptional activation of the mTOR pathway and ribosome biogenesis, and resulted in enlarged hearts with cardiomyocyte hypertrophy. Intriguingly, mutant p.S358L TMEM43 was found to be unstable and partially redistributed into the cytoplasm in embryonic and adult hearts. Moreover, both TMEM43 variants displayed cardiac morphological defects at juvenile stages and ultrastructural changes within the myocardium, accompanied by dysregulated gene expression profiles in adulthood. Finally, CRISPR/Cas9 mutants demonstrated an age-dependent cardiac phenotype characterized by heart enlargement in adulthood. In conclusion, our findings suggest ultrastructural remodeling and transcriptomic alterations underlying the development of structural and functional cardiac defects in TMEM43-associated cardiomyopathy.}, language = {en} } @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{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} } @article{SchreiberLohrBaltesetal.2023, author = {Schreiber, Laura M. and Lohr, David and Baltes, Steffen and Vogel, Ulrich and Elabyad, Ibrahim A. and Bille, Maya and Reiter, Theresa and Kosmala, Aleksander and Gassenmaier, Tobias and Stefanescu, Maria R. and Kollmann, Alena and Aures, Julia and Schnitter, Florian and Pali, Mihaela and Ueda, Yuichiro and Williams, Tatiana and Christa, Martin and Hofmann, Ulrich and Bauer, Wolfgang and Gerull, Brenda and Zernecke, Alma and Erg{\"u}n, S{\"u}leyman and Terekhov, Maxim}, title = {Ultra-high field cardiac MRI in large animals and humans for translational cardiovascular research}, series = {Frontiers in Cardiovascular Medicine}, volume = {10}, journal = {Frontiers in Cardiovascular Medicine}, issn = {2297-055X}, doi = {10.3389/fcvm.2023.1068390}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-317398}, year = {2023}, abstract = {A key step in translational cardiovascular research is the use of large animal models to better understand normal and abnormal physiology, to test drugs or interventions, or to perform studies which would be considered unethical in human subjects. Ultrahigh field magnetic resonance imaging (UHF-MRI) at 7 T field strength is becoming increasingly available for imaging of the heart and, when compared to clinically established field strengths, promises better image quality and image information content, more precise functional analysis, potentially new image contrasts, and as all in-vivo imaging techniques, a reduction of the number of animals per study because of the possibility to scan every animal repeatedly. We present here a solution to the dual use problem of whole-body UHF-MRI systems, which are typically installed in clinical environments, to both UHF-MRI in large animals and humans. Moreover, we provide evidence that in such a research infrastructure UHF-MRI, and ideally combined with a standard small-bore UHF-MRI system, can contribute to a variety of spatial scales in translational cardiovascular research: from cardiac organoids, Zebra fish and rodent hearts to large animal models such as pigs and humans. We present pilot data from serial CINE, late gadolinium enhancement, and susceptibility weighted UHF-MRI in a myocardial infarction model over eight weeks. In 14 pigs which were delivered from a breeding facility in a national SARS-CoV-2 hotspot, we found no infection in the incoming pigs. Human scanning using CINE and phase contrast flow measurements provided good image quality of the left and right ventricle. Agreement of functional analysis between CINE and phase contrast MRI was excellent. MRI in arrested hearts or excised vascular tissue for MRI-based histologic imaging, structural imaging of myofiber and vascular smooth muscle cell architecture using high-resolution diffusion tensor imaging, and UHF-MRI for monitoring free radicals as a surrogate for MRI of reactive oxygen species in studies of oxidative stress are demonstrated. We conclude that UHF-MRI has the potential to become an important precision imaging modality in translational cardiovascular research.}, 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{KolokotronisPlutaKlopockietal.2020, author = {Kolokotronis, Konstantinos and Pluta, Natalie and Klopocki, Eva and Kunstmann, Erdmute and Messroghli, Daniel and Maack, Christoph and Tejman-Yarden, Shai and Arad, Michael and Rost, Simone and Gerull, Brenda}, title = {New Insights on Genetic Diagnostics in Cardiomyopathy and Arrhythmia Patients Gained by Stepwise Exome Data Analysis}, series = {Journal of Clinical Medicine}, volume = {9}, journal = {Journal of Clinical Medicine}, number = {7}, doi = {10.3390/jcm9072168}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-236094}, year = {2020}, abstract = {Inherited cardiomyopathies are characterized by clinical and genetic heterogeneity that challenge genetic diagnostics. In this study, we examined the diagnostic benefit of exome data compared to targeted gene panel analyses, and we propose new candidate genes. We performed exome sequencing in a cohort of 61 consecutive patients with a diagnosis of cardiomyopathy or primary arrhythmia, and we analyzed the data following a stepwise approach. Overall, in 64\% of patients, a variant of interest (VOI) was detected. The detection rate in the main sub-cohort consisting of patients with dilated cardiomyopathy (DCM) was much higher than previously reported (25/36; 69\%). The majority of VOIs were found in disease-specific panels, while a further analysis of an extended panel and exome data led to an additional diagnostic yield of 13\% and 5\%, respectively. Exome data analysis also detected variants in candidate genes whose functional profile suggested a probable pathogenetic role, the strongest candidate being a truncating variant in STK38. In conclusion, although the diagnostic yield of gene panels is acceptable for routine diagnostics, the genetic heterogeneity of cardiomyopathies and the presence of still-unknown causes favor exome sequencing, which enables the detection of interesting phenotype-genotype correlations, as well as the identification of novel candidate genes.}, language = {en} } @article{JanzZinkCirnuetal.2021, author = {Janz, Anna and Zink, Miriam and Cirnu, Alexandra and Hartleb, Annika and Albrecht, Christina and Rost, Simone and Klopocki, Eva and G{\"u}nther, Katharina and Edenhofer, Frank and Erg{\"u}n, S{\"u}leyman and Gerull, Brenda}, title = {CRISPR/Cas9-edited PKP2 knock-out (JMUi001-A-2) and DSG2 knock-out (JMUi001-A-3) iPSC lines as an isogenic human model system for arrhythmogenic cardiomyopathy (ACM)}, series = {Stem Cell Research}, volume = {53}, journal = {Stem Cell Research}, doi = {10.1016/j.scr.2021.102256}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-259846}, pages = {102256}, year = {2021}, abstract = {Arrhythmogenic cardiomyopathy (ACM) is characterized by fibro-fatty replacement of the myocardium, heart failure and life-threatening ventricular arrhythmias. Causal mutations were identified in genes encoding for proteins of the desmosomes, predominantly plakophilin-2 (PKP2) and desmoglein-2 (DSG2). We generated gene-edited knock-out iPSC lines for PKP2 (JMUi001-A-2) and DSG2 (JMUi001-A-3) using the CRISPR/Cas9 system in a healthy control iPSC background (JMUi001A). Stem cell-like morphology, robust expression of pluripotency markers, embryoid body formation and normal karyotypes confirmed the generation of high quality iPSCs to provide a novel isogenic human in vitro model system mimicking ACM when differentiated into cardiomyocytes.}, 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{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{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} }