Single cell RNA transcriptome analysis of Epicardial Derived Cells in the Desmoplakin haplo-insufficient Arrhythmogenic Cardiomyopathy mouse
To delineate the role of the epicardium, the initial site of presentation of the ACM phenotype, the Dsp gene, encoding desmosome protein desmoplakin (DSP) was conditionally deleted in the mouse epicardial cells under the transcriptional regulation of Wilms tumor 1 (Wt1) locus.  Single cell RNA sequencing (scRNA-Seq) of ~ 40,000 tagged epicardial-derived cells (EDCs), isolated using the dual reporter R26mT/mG mice, showed an increased number of EDCs expressing unique molecular identifiers of fibroblasts as well as a unique subset of epicardial-derived fibroblasts expressing pro-fibrotic genes in the Wt1-Cre: R26mT/mG: Dsp mice. Analysis of pseudo-bulk RNA-Seq data identified ~ 800 differentially expressed genes (DEGs), which were predominantly involved in epithelial-mesenchymal transition (EMT). The DEGs were the targets of TGFB1 among other trophic/mitotic factors, whose activation was verified by immunohistochemistry and quantification of transcript levels of selected TGBF1 pathway genes. Retro-mapping of the DEGs to the cell clusters, identified by scRNA-Seq, denoted epicardial-derived fibroblasts and to a lesser extent the epithelial cells as the main sources of paracrine factors in the myocardium of Wt1-Cre: R26mT/mG: Dsp mice. Overall design: Integrative analysis of epicardial derived single-cell RNA-seq in the Desmoplakin haplo-insufficient Arrhythmogenic Cardiomyopathy mouse model.