FUNCTIONAL CHARACTERIZATION OF CORONARY ARTERY DISEASE GWAS CANDIDATE GENES REVEALS A NOVEL ROLE FOR ATXN2 IN SMOOTH MUSCLE CELL PHENOTYPE SWITCHING

Abstract

Coronary Artery Disease (CAD) is the leading cause of morbidity and mortality in Qatar and across the world. The underlying cause of CAD is the build-up of atherosclerotic plaque in the coronary arteries. Phenotype switching of vascular smooth muscle cells (VSMC) between their synthetic and differentiated contractile state is a critical player in controlling the development and stability of atherosclerotic plaque. Hundreds of genes associated with CAD have been identified through Genome-Wide Association Studies (GWAS). However, the involvement of most identified genes in VSMC phenotype switching remains unknown. In the current project, we conducted a phenotypic high throughput cell-based RNAi screen of GWAS gene candidates to identify their functional role in human aortic SMC phenotype switching. A primary screen of a siRNA library to knockdown 411 GWAS gene candidates yielded 45 gene siRNAs that enhance or inhibit the SMC phenotype switching. Furthermore, we explored the expression signature of these 45 genes in different subsets of VSMC from human atherosclerotic plaque and proximal adjacent tissue samples using single-cell RNA sequencing analysis. Interestingly, we detected the expression signature of the ATXN2 gene in different subsets of VSMC from human atherosclerotic plaque samples. Since the functional role of ATXN2 in VSMC biology was previously unknown, it was selected for further validation and mechanistic studies. First, we confirmed that ATXN2 siRNA knockdown enhances VSMC contractile phenotype. We found that the enhancing effect of VSMC contractile phenotype by ATXN2 siRNA is mediated by the crosstalk between EGFR and TGF-b1 signaling. Our findings identified ATXN2 as a novel therapeutic target to enhance the VSMC contractile phenotype for stabilizing atherosclerotic plaque in coronary artery disease patients.

Date of Award	2024
Original language	American English
Awarding Institution	HBKU College of Health & Life Sciences