Abstract Body (Do not enter title and authors here): Introduction: While genetic variants linked to dilated cardiomyopathy (DCM) are increasingly well characterized, the molecular mechanisms driving pathogenesis remain poorly understood. Traditional bulk and in vitro methods lack the resolution to capture the cellular heterogeneity and complexity of DCM. Here, we use single-nucleus multiome chromatin accessibility and RNA sequencing to resolve cell-type-specific gene regulatory changes in genetic DCM.

Methods: We performed 10X Genomics Multiome (simultaneous RNA and chromatin accessibility) profiling on nuclei isolated from left ventricular tissue of 13 DCM patients with diverse genetic etiologies (LMNA, PLN, RBM20, TNNT2, TTN) and 5 non-failing hearts. Integrated analysis identified 12 distinct cardiac cell types based on joint transcriptomic and epigenomic signatures. Intercellular communication networks were inferred using CellChat. We leveraged paired RNA and chromatin accessibility data to elucidate potential enhancer-gene interactions driving disease-associated cell state changes.

Results: We observed disease-specific alterations in cellular composition and signaling networks across DCM genetic etiologies. Integrated chromatin accessibility and gene expression data revealed changes in the gene regulatory networks of cardiomyocytes, fibroblasts, and endothelial cells. Notably, the transcription factor PRRX1 emerged as a key differentially regulated gene in LMNA-related DCM. Functional assays in iPSC-derived cardiomyocytes demonstrated that PRRX1 knockdown significantly improved calcium handling and reduced arrythmia incidence.

Conclusions: This single nucleus multiomic atlas of genetic DCM provides insights into cell-type-specific gene regulation and cell communication programs associated with disease states. Our findings highlight PRRX1 as a potential therapeutic target in LMNA-related DCM and underscore the value of multiomic profiling for uncovering the regulatory basis of cardiomyopathies.