Patient-specific hiPSC-derived cardiomyocytes indicate allelic and contractile imbalance as pathogenic factor in early-stage Hypertrophic Cardiomyopathy

Natalie Weber; Judith Montag; Kathrin Kowalski; Bogdan Iorga; Jeanne de la Roche; Tim Holler; Daniel Wojciechowski; Meike Wendland; Ante Radocaj; Anne-Kathrin Mayer; Anja Brunkhorst; Felix Osten; Valentin Burkart; Birgit Piep; Alea Bodenschatz; Pia Gibron; Kristin Schwanke; Annika Franke; Stefan Thiemann; Anastasia Koroleva; Angelika Pfanne; Maike Konsanke; Jan Fiedler; Jan Hegermann; Christoph Wrede; Christian Mühlfeld; Boris Chichkov; Martin Fischer; Thomas Thum; Antonio Francino; Ulrich Martin; Joachim Meißner; Robert Zweigerdt; Theresia Kraft

doi:10.1016/j.yjmcc.2024.11.007

Patient-specific hiPSC-derived cardiomyocytes indicate allelic and contractile imbalance as pathogenic factor in early-stage Hypertrophic Cardiomyopathy

J Mol Cell Cardiol. 2024 Dec 7:198:112-125. doi: 10.1016/j.yjmcc.2024.11.007. Online ahead of print.

Authors

Natalie Weber¹, Judith Montag², Kathrin Kowalski³, Bogdan Iorga⁴, Jeanne de la Roche⁵, Tim Holler³, Daniel Wojciechowski⁵, Meike Wendland³, Ante Radocaj³, Anne-Kathrin Mayer³, Anja Brunkhorst³, Felix Osten³, Valentin Burkart³, Birgit Piep³, Alea Bodenschatz³, Pia Gibron³, Kristin Schwanke⁶, Annika Franke⁶, Stefan Thiemann⁵, Anastasia Koroleva⁷, Angelika Pfanne⁸, Maike Konsanke⁹, Jan Fiedler¹⁰, Jan Hegermann¹¹, Christoph Wrede¹¹, Christian Mühlfeld¹¹, Boris Chichkov⁷, Martin Fischer⁵, Thomas Thum⁸, Antonio Francino¹², Ulrich Martin⁶, Joachim Meißner³, Robert Zweigerdt⁶, Theresia Kraft³

Affiliations

¹ Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany; Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Hannover, Germany. Electronic address: [email protected].
² Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany; Department of Human Medicine, Medical School Berlin, Berlin, Germany. Electronic address: [email protected].
³ Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany.
⁴ Institute for Molecular and Cell Physiology, Hannover Medical School, Hannover, Germany; Department of Analytical Chemistry and Physical Chemistry, Faculty of Chemistry, University of Bucharest, Bucharest, Romania.
⁵ Institute for Neurophysiology, Hannover Medical School, Hannover, Germany.
⁶ Leibniz Research Laboratories for Biotechnology and Artificial Organs (LEBAO), Department of Cardiothoracic, Transplantation and Vascular Surgery, Hannover Medical School, Hannover, Germany.
⁷ Institute for Quantum Optics, Leibniz University Hannover, Hannover, Germany.
⁸ Institute of Molecular and Translational Therapeutic Strategies (IMTTS), Hannover Medical School, Hannover, Germany.
⁹ Research Core Unit Genomics, Hannover Medical School, Hannover, Germany.
¹⁰ Fraunhofer Institute for Toxicology and Experimental Medicine (ITEM), Hanover, Germany.
¹¹ Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, Germany; Biomedical Research in Endstage and Obstructive Lung Disease Hannover (BREATH), Member of the German Center for Lung Research (DZL), Hannover, Germany.
¹² Hospital Clinic/IDIBAPS, University of Barcelona, Barcelona, Spain.

PMID: 39647438
DOI: 10.1016/j.yjmcc.2024.11.007

Abstract

Hypertrophic Cardiomyopathy (HCM) is often caused by heterozygous mutations in β-myosin heavy chain (MYH7, β-MyHC). In addition to hyper- or hypocontractile effects of HCM-mutations, heterogeneity in contractile function (contractile imbalance) among individual cardiomyocytes was observed in end-stage HCM-myocardium. Contractile imbalance might be induced by burst-like transcription, leading to unequal fractions of mutant versus wildtype mRNA and protein in individual cardiomyocytes (allelic imbalance). Until now it is not known if allelic and contractile imbalance are present early in HCM-development or rather occur in response to disease-associated remodeling. To address this question, we used patient-specific human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) with heterozygous MYH7-mutations R723G and G741R as models of early-stage HCM without secondary adaptions upon disease progression. R723G-hiPSC-CMs showed typical HCM-markers like hypertrophy and myofibrillar disarray. Using RNA-FISH and allele-specific single-cell-PCR, we show for both cell lines that MYH7 is transcribed in bursts. Highly variable mutant vs. wildtype MYH7-mRNA fractions in individual HCM-hiPSC-CMs indicated allelic imbalance. HCM-hiPSC-CM-lines showed functional alterations like slowed twitch contraction kinetics and reduced calcium sensitivity of myofibrillar force generation. A significantly larger variability in force generation or twitch parameters of individual HCM-hiPSC-CMs compared to WT-hiPSC-CMs indicated contractile imbalance. Our results with early-stage hiPSC-CMs strongly suggest that burst-like transcription and allelic imbalance are general features of CMs, which together with mutation-induced changes of sarcomere contraction could induce contractile imbalance in heterozygous CMs, presumably aggravating development of HCM. Genetic or epigenetic approaches targeting functional heterogeneity in HCM could lead to promising future therapies, in addition to myosin modulation.

Keywords: Allelic imbalance; Contractile imbalance; Hypertrophic cardiomyopathy; R723G myosin mutation; hiPSC-derived cardiomyocytes.