Down-regulated RGS5 by genetic variants impairs endothelial cell function and contributes to coronary artery disease

Aims Genetic contribution to coronary artery disease (CAD) remains largely unillustrated. Although transcriptomic profiles have identified dozens of genes that are differentially expressed in normal and atherosclerotic vessels, whether those genes are genetically associated with CAD remains to be determined. Here, we combined genetic association studies, transcriptome profiles and in vitro and in vivo functional experiments to identify novel susceptibility genes for CAD. Methods and results Through an integrative analysis of transcriptome profiles with genome-wide association studies for CAD, we obtained 18 candidate genes and selected one representative single nucleotide polymorphism (SNP) for each gene for multi-centred validations. We identified an intragenic SNP, rs1056515 in RGSS gene (odds ratio = 1.17, 95% confidence interval =1.10 1.24, P = 3.72 x 10(-)(8)) associated with CAD at genome-wide significance. Rare genetic variants in linkage disequilibrium with rs1056515 were identified in CAD patients leading to a decreased expression of RGS5. The decreased expression was also observed in atherosclerotic vessels and endothelial cells treated by various cardiovascular risk factors. Through siRNA knockdown and adenoviral overexpression, we further showed that RGSS regulated endothelial inflammation, vascular remodelling, as well as canonical NF-kappa B signalling activation. Moreover, CXCL12, a specific downstream target of the non-canonical NF-kappa B. pathway, was strongly affected by RGSS. However, the p100 processing, a well-documented marker for non-canonical NF-kappa B pathway activation, was not altered, suggesting an existence of a novel mechanism by which RGS5 regulates CXCL12. Conclusions We identified RGS5 as a novel susceptibility gene for CAD and showed that the decreased expression of RGSS impaired endothelial cell function and functionally contributed to atherosclerosis through a variety of molecular mechanisms. How RGS5 regulates the expression of CXCL12 needs further studies. [GRAPHICS] .

Automated summary

This study identified RGS5 as a novel susceptibility gene for CAD through integrative analysis of transcriptome profiles with genome-wide association studies. Decreased expression of RGS5 was shown to impair endothelial cell function and functionally contribute to atherosclerosis through various molecular mechanisms. Further studies are needed to elucidate how RGS5 regulates the expression of CXCL12.