Classical family-based genetic studies have convincingly demonstrated that genes have a large effect on the risk of cardiovascular disease (CVD);their identification however is proving elusive. We have recently combined quantitative genome-wide mRNA expression phenotypes with linkage analysis in our SAFHS study population to identify the Vanin-1 gene on chromosome 6q22 as a novel CVD risk factor. Vanin-1 is a pantetheinase that catalyzes the hydrolysis of D-pantetheine generating pantothenate (vitamin B5) and cysteamine, a potent anti-oxidant known to prevent lipid peroxidation. We have shown that the expression of Vanin-1 is cis-regulated and correlates positively with HDL-C levels in both humans and baboons and negatively with triglyceride (TG) levels in humans. In mice, reduced vanin-1 levels also are associated with a more CVD - prone phenotype of increased TG levels, as seen in humans. These results suggest that the Vanin-1 gene may be potentially involved in lipid mediation. In this project we propose to use an integrative genomics approach to comprehensively determine how the Vanin-1 gene is transcriptionally regulated and to identify other (perhaps novel) genes that participate with Vanin-1 in the global regulatory networks that confer risk of CVD. Specifically, we will: 1) identify the functional SNPs that influence Vanin-1 gene expression starting with our statistically prioritized isocorrelated redundant variant sets;2) identify the remaining non- variant DNA regulatory elements and associated transcription factors that control basal and inducible Vanin-1 gene expression;3) identify and validate upstream regulators of Vanin-1 expression levels using genome-wide association analysis and in vitro knockdown experiments;4) identify downstream genes in the Vanin-1 regulatory networks by association with functional Vanin-1 regulatory variants, and validate by in vitro knockdown;and 5) validate any novel upstream or downstream genes identified in Aims 2 - 4 using SNP- based association analyses with CVD-related risk phenotypes such as HDL-C, TG, and carotid-wall thickness. Any novel insight into biological mechanisms that predispose individuals to CVD holds the promise of potential new therapies and a significant reduction of this considerable health burden.
Despite the current availability of therapies involving lipid-lowering drugs the incidence of cardiovascular disease (CVD) remains very high, indicating that there is a need for additional therapeutic strategies. Many lines of evidence suggest that aside from adopting healthy lifestyle habits, patients with established CVD, and those at high risk, may benefit from drugs that increase circulating levels of HDL-C (the good cholesterol). We have recently identified a gene that appears to be involved in the regulation of lipid levels, and in particular HDL-C levels. In this project we aim to understand how this gene is regulated and the mechanisms by which it exerts lipid-modifying effects. The knowledge gained may lead to better methods for identifying those at greatest risk of CVD and point to new strategies for drug therapy.
