Single-nucleus RNA-sequencing in a transgenic murine model of arrhythmogenic cardiomyopathy identified a specific cardiomyocyte subtype characterized by upregulated oxidative phosphorylation genes.
Single-nucleus RNA-sequencing in a novel DSG2 murine model of arrhythmogenic cardiomyopathy reveals a specific cardiomyocyte subtype with enhanced oxidative metabolism and highlights endothelial cells' role in early disease progression.
Abstract Background Arrhythmogenic cardiomyopathy (ACM) is a genetic disorder primarily caused by pathogenic variants in desmosomal protein-coding genes. It is pathologically defined by the fibro-fatty myocardial replacement and clinically associated with ventricular arrhythmias and sudden cardiac death (SCD). Although ACM is the second leading cause of SCD in young adults and athletes, the molecular mechanisms driving fibro-fatty replacement remain poorly characterized, limiting the development of targeted therapies. Purpose This study aims to uncover novel pathogenic mechanisms underlying ACM using single-nucleus RNA-sequencing (snRNA-seq) performed in the heart of a novel transgenic murine model (Tg-hG) overexpressing the human desmoglein 2 (DSG2) carrying the p.G100R variant. By mapping cell-type-specific transcriptional alterations at high resolution, we seek to improve our understanding of the disease and pave the way for more effective, targeted therapies to reduce the burden of ACM. Methods Transgenic mice overexpressing the human DSG2 p.G100R variation specifically in cardiomyocytes were generated and extensively phenotyped at molecular, structural and functional levels to detect ACM features. Next, left and right ventricles of six-month-old Tg-hG and control mice were collected and nuclei were isolated following standard procedures. snRNA-seq was performed with transcriptome alignment, UMI quantification, and quality filtering. Unsupervised clustering, differential gene expression and gene ontology analyses were conducted. A Cytoscape interaction network was built to explore intercellular communication. Results Tg-hG mice present key features of cardiac disease, such as fibrous replacement, increased inflammatory markers, and cardiac dysfunction, starting from six months of age. Seven cell populations were identified. Notably, specific cardiomyocyte, fibroblasts and endothelial cells subclusters were enriched in Tg-hG hearts. Interestingly, Tg-hG-specific cardiomyocytes clusters showed a strong upregulation of oxidative phosphorylation genes, suggesting a shift toward enhanced oxidative metabolism. Network analysis highlighted a dense pattern of interactions centered on endothelial cells, underlining their potential coordinating role in the pathological response. These findings were independently validated in a second transgenic mouse model overexpressing a DSG2 nonsense variant. Conclusions This study identified a Tg-hG exclusive subtype of cardiomyocytes characterized by a higher metabolic state. Network analysis revealed an intricate crosstalk among cardiac cell types during early disease progression. By refining the current cellular and molecular landscape of ACM, these data open new venues for the development of targeted therapies for the disease.
Serrecchia et al. (Fri,) conducted a other in Arrhythmogenic cardiomyopathy. Transgenic overexpression of human DSG2 p.G100R variant vs. Control mice was evaluated on Cell-type-specific transcriptional alterations. Single-nucleus RNA-sequencing in a transgenic murine model of arrhythmogenic cardiomyopathy identified a specific cardiomyocyte subtype characterized by upregulated oxidative phosphorylation genes.