Quantitative trait loci mapped for TCF21 binding, chromatin accessibility and chromosomal looping in coronary artery smooth muscle cells reveal molecular mechanisms of coronary disease loci

To better understand the fundamental molecular mechanisms that contribute to complex human diseases such as coronary artery disease (CAD), we have created a catalog of genetic variants associated with three stages of transcriptional cis-regulation in primary human coronary artery vascular smooth muscle cells. To this end, we used a pooling approach to map quantitative trait locus associations (QTLs) for TCF21 binding (ChIPseq), chromatin accessibility (ATACseq), and chromosomal looping (HiC). We find significant overlap of these QTLs, and several analyses indicate their relationship to smooth muscle specific genes, the binding of smooth muscle transcription factors, and enrichment in CAD-associated loci. These QTLs are extensively validated and allele-specific chromatin looping at the FN1 disease locus is shown to be mediated by activation of the CAD-associated TGFb1 pathway. In sum, these results uncover thousands of loci affecting cis-regulation in a key cell type for CAD, including many that may contribute to CAD risk. 72 Human coronary artery smooth muscle cells (HCASMC) grown in serum. Approximately 1M cells per sample were freshly prepared for nuclei extraction.