Abstract 12513: Post-GWAS Functional Analysis of the CDKN2A/B Locus Identifies CUX1 as a Regulator of Endothelial Senescence by Modulating the CAD-Associated p16 INK4A Expression

Abstract

Introduction: Genome-wide association studies (GWAS) have validated a strong association of the CDKN2A/B locus with more than 10 different age-related diseases including atherosclerosis and its complications. Hypothesis: The CDKN2A/B locus is one of the most complicated genetic loci that harbors p16INK4a, one of the markers for cellular senescence. As a single locus associates with multiple different age-related diseases, this region may contribute to the progression of these diseases by promoting aging itself, perhaps through modulating cellular senescence. Methods: By coupling regulatory element-sequencing (Reel-seq) with SNP-specific DNA competition pulldown-mass spectrometry (SDCP-MS), two techniques recently developed in our lab, the disease-associated functional SNPs (fSNP) on the CDKN2A/B locus and the fSNP binding proteins were identified. The mechanism underlying the contribution of an atherosclerosis-associated fSNP rs1537371 to the pathogenesis of, and the susceptibility to atherosclerosis was revealed by contemporary techniques. Results: We demonstrate that the homeodomain transcription factor CUX1 specifically binds to the atherosclerosis-associated fSNP rs1537371 within the CDKN2A/B locus. Although it binds at a considerable distance (> 100 kb), CUX1 is shown to regulate the CDKN2A/B encoded genes p14 ARF , p16 INK4A , p15 INK4B and ANRIL in endothelial cells (ECs). In-depth analysis demonstrates that endothelial CUX1 expression correlates with telomeric length and is induced by both DNA-damaging agents and oxidative stress. Moreover, induction of CUX1 expression triggers both replicative and stress-induced premature senescence via activating p16 INK4A expression. Consistent with these findings, we also detect elevated expression of CUX1 and p16 INK4A in the plaques of patients with carotid artery disease. Conclusions: CUX1 is a transcriptional regulator of p16 INK4A expression. It regulates p16 INK4A -dependent endothelial senescence via binding to the atherosclerosis-associated fSNP rs1537371.