Abstract P1015: Functional Investigation Of The Coronary Artery Disease Risk Gene Rest In Atherosclerosis

Abstract

Background: GWAS discovered two CAD risk variants, rs17087335 and rs72627509, located downstream of REST (RE1-silencing transcription factor). So far, REST has been mainly associated with neurological diseases, while its role in vascular function remains unclear. Here, we aimed to explore the role of REST in atherosclerosis. Methods and Results: Transcriptome data from the GTEx consortium hinted towards an association of reduced REST expression in vascular tissues with the risk alleles of rs17087335 and rs72627509. We performed reporter gene assays in HEK293 cells using constructs that contain the REST promoter upstream and the SNP sequence (200 bp) downstream of the reporter gene. In line with the GTEx data, the luciferase assays showed reduced reporter gene activity with the risk alleles of both variants. We next studied the function of REST in different atherosclerosis-relevant vascular cell types, such as human vascular smooth muscle cells (HVSMC) and human vascular endothelial cells (HVEC). In HVEC, siRNA-mediated REST downregulation experiments revealed no changes in HVEC proliferation or migration. In HVSMC, in contrast, migration was significantly enhanced secondary to REST knockdown. Furthermore, reduced REST led to increased uptake of lipids into HVSMC under inflammatory conditions. To elucidate putative molecular pathways, we performed RNA sequencing in HVSMC secondary to REST downregulation. Surprisingly, we detected downregulation of ATF6 (ActivatingTranscription Factor 6) upon REST knockdown, which was confirmed by qPCR. In silico analysis revealed several REST binding sites at the ATF6 promoter. ATF6 plays a role in endoplasmatic reticulum (ER) stress, which has been reported to contribute to a macrophage-/fibroblast-like lipid-loaden phenotype of SMC. In line with the findings for REST, we could show that decreased ATF6 results in increased lipid uptake by HVSMC. Conclusion and Outlook: We provide first evidence that reduced REST expression may increase the risk of atherosclerosis and CAD via promoting HVSMC migration and a phenotypic switch towards macrophage-/fibroblast-like lipid-loaden SMC. These effects might be mediated via ATF6 . Modulation of REST might be a new strategy for preventing and treating CAD.