A DNA damage checkpoint drives phenotypic transition in cardiomyopathy

Background Hypertrophic cardiomyopathy (HCM) arises from sarcomeric gene mutations, yet the mechanisms determining whether hypertrophic remodelling remains compensated or progresses to heart failure remain unresolved. Although energetic demand and oxidative stress are increased in HCM, whether these changes reflect metabolic adaptation or directly regulate myocardial phenotypic transition is unclear. We hypothesised that oxidative DNA damage functions as a genomic stress checkpoint regulating the transition from compensated hypertrophy to decompensated failure. Purpose To elucidate the molecular mechanisms underlying hypertrophic remodelling and heart failure progression in HCM. Methods We analysed myocardial samples from patients with preserved and end-stage HCM, generated a Mybpc3 mutant mouse model recapitulating disease progression, performed single-cell RNA sequencing including pseudotime analysis, and conducted machine learning–guided drug screening using patient-derived induced pluripotent stem cell–derived cardiomyocytes (iPS-CMs). Oxidative stress modulation was evaluated in vitro and in vivo. Results Human myocardial samples showed progressive DNA damage accumulation closely associated with left ventricular systolic dysfunction (LVSD, Figure 1A). Single-cell transcriptomics of Mybpc3 mutant hearts revealed a temporally ordered trajectory in which early hypertrophic myocardium displayed enhanced oxidative phosphorylation and fatty acid metabolism, whereas failing myocardium activated DNA damage responses, NF-κB–mediated inflammation and TGF-β–dependent fibrotic programmes. Trajectory inference identified oxidative stress–associated genomic injury as an inflection point preceding inflammatory and profibrotic reprogramming (Figure 1B). Oxidative stress progressively accumulated in vivo, with increasing 4-hydroxynonenal levels peaking in the dilated phase (Figure 1C), and γH2AX staining confirming stage-dependent cardiomyocyte DNA damage (Figure 1D). To test causality, we generated patient-derived iPSC-CMs and performed machine learning–guided screening. Deep learning–based phenotypic analysis confirmed hypertrophy in HCM iPSC-CMs and identified Quercetin as a suppressor (Figure 2A). Graded reactive oxygen species (ROS) exposure induced dose-dependent DNA damage with a threshold beyond which contractile dysfunction emerged (Figure 2B, C). In vivo, Quercetin attenuated hypertrophy and prevented functional decline, accompanied by suppression of inflammatory and apoptotic programmes and preservation of oxidative phosphorylation signatures (Figure 2D–G). Conclusion Oxidative DNA damage acts as a threshold-dependent regulator of myocardial fate, linking sarcomeric mutation to maladaptive remodelling. Sustained ROS accumulation triggers checkpoint-dependent transcriptional reprogramming and functional decline. These findings redefine heart failure progression in HCM as a regulated phenotypic transition governed by genomic stress.