In Vivo Analysis of a Noncoding Susceptibility Region for Coronary Artery Disease

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DESCRIPTION (provided by applicant): Large epidemiological studies have indicated that genetic factors contribute significantly to the development of coronary atherosclerosis, a major cause of morbidity and mortality in Western countries. Through genome-wide association studies (GWASs), we and others have identified a strong link between a 58kb noncoding region on 9p21 and coronary artery disease (CAD). The mechanism by which sequence variation at this locus influences CAD is not known since the interval does not contain any protein-coding genes. To provide an animal model to study this CAD-associated noncoding region, we have deleted the orthologous interval (chr4?70kb) from the mouse genome and show that it significantly impacts on cardiac expression of two genes (Cdkn2a and Cdkn2b) adjacent to the deletion. Accordingly, the central goal of this application is to use this and other genetically engineered mice to uncover the mechanism by which sequence variation in this noncoding interval confers susceptibility to CAD. The specific aims are to (1) identify genes/pathways abnormally expressed in the chr4?70kb mice, (2) to identify and characterize transcriptional enhancers within the deleted interval through a transgenic mouse enhancer assay, (3) to test CAD-associated sequence variants in the enhancers that we have identified in the linkage disequilibrium interval for their impact on gene expression in vivo, and (4) to determine the effect of the chr4?70kb deletion on murine atherosclerosis susceptibility and cellular proliferation. These studies will explore the mechanism of how the human 9p21 linkage disequilibrium region causes CAD susceptibility and serve as a paradigm for relating disease-associated DNA sequence variants occurring in noncoding regions to clinically relevant phenotypes. PUBLIC HEALTH RELEVANCE: Genome-wide association studies (GWASs) have revealed a number of genomic intervals that contribute to human disease but are devoid of protein-coding genes. Remarkably, many individuals have a substantially increased risk for developing coronary artery disease due to sequence variations in a noncoding region of human chromosome 9p21, yet the disease- causing mechanism remains cryptic. Accordingly, we propose to utilize genetically engineered mouse models to study in a controlled laboratory setting how these noncoding sequence changes lead to heart disease in humans.