Abstract EC.09: Single Nuclei RNA Sequencing Analysis Of Mybpc-3- Associated HCM To Identify Common Pathological Mechanisms In Human, Feline, And Murine Hearts

Abstract

Hypertrophic cardiomyopathy (HCM) is a common inherited cardiovascular disease characterized by unexplained hypertrophy, often associated with left ventricular outflow tract (LVOT) obstruction, ventricular tachyarrhythmias, diastolic heart failure, and sudden cardiac death. Mutations in mybpc3 are the most common genetic mutations associated with human and feline HCM. To understand how mutations in mybc3 causing sarcomere dysfunction result in the development of non-myocyte phenotypes such as fibrosis, mitral valve anomalies, and microvascular occlusion across species, we generated single nuclei RNA-sequencing datasets from feline, human and murine heart tissue carrying mybpc3 variants. We analyzed these datasets for differential gene expression by genotype for each cell type and assessed changes in cell-cell communication by ligand-receptor analysis. Gene Ontology (GO) enrichment analysis of differentially expressed genes (DEGs) in feline cardiomyocytes revealed alteration in regulation of calcium ion transmembrane transporter activity, regulation of cation channel activity, and extracellular matrix structure and organization, consistent with known phenotypic aspects of HCM such as calcium dyshomeostasis and fibrosis. DEGs in cardiomyocytes of human tissues revealed novel obstruction of cGMP-mediated signaling, protein O-linked glycosylation and negative regulation of cAMP-mediated signaling. DEGs in murine cardiomyocytes affected cardiac muscle thin filament assembly, CDP-diacylglycerol biosynthesis and cell adhesion molecule production. Analysis of intercellular communication in feline and murine hearts revealed an overall loss of ligands broadcast from all cell types, with notable losses from fibroblast cells and cardiomyocytes. These findings are consistent with recent studies implicating altered intercellular communication between cardiomyocytes and non-myocyte cell types as a potential disease mechanism in human HCM. We will further identify common and species-specific disease-promoting pathways in HCM tissue that will allow identification of conserved disease mechanisms that may be targeted in both human and feline disease and will facilitate an understanding of the relevance of mouse models.