Coronary-Heart-Disease-Associated Genetic Variant at the COL4A1/COL4A2 Locus Affects COL4A1/COL4A2 Expression, Vascular Cell Survival, Atherosclerotic Plaque Stability and Risk of Myocardial Infarction

Abstract

Genome-wide association studies have revealed an association between coronary heart disease (CHD) and genetic variation on chromosome 13q34, with the lead single nucleotide polymorphism rs4773144 residing in the COL4A2 gene in this genomic region. We investigated the functional effects of this genetic variant. Analyses of primary cultures of vascular smooth muscle cells (SMCs) and endothelial cells (ECs) from different individuals showed a difference between rs4773144 genotypes in COL4A2 and COL4A1 expression levels, being lowest in the G/G genotype, intermediate in A/G and highest in A/A. Chromatin immunoprecipitation followed by allelic imbalance assays of primary cultures of SMCs and ECs that were of the A/G genotype revealed that the G allele had lower transcriptional activity than the A allele. Electrophoretic mobility shift assays and luciferase reporter gene assays showed that a short DNA sequence encompassing the rs4773144 site interacted with a nuclear protein, with lower efficiency for the G allele, and that the G allele sequence had lower activity in driving reporter gene expression. Analyses of cultured SMCs from different individuals demonstrated that cells of the G/G genotype had higher apoptosis rates. Immunohistochemical and histological examinations of ex vivo atherosclerotic coronary arteries from different individuals disclosed that atherosclerotic plaques with the G/G genotype had lower collagen IV abundance and thinner fibrous cap, a hallmark of unstable, rupture-prone plaques. A study of a cohort of patients with angiographically documented coronary artery disease showed that patients of the G/G genotype had higher rates of myocardial infarction, a phenotype often caused by plaque rupture. These results indicate that the CHD-related genetic variant at the COL4A2 locus affects COL4A2/COL4A1 expression, SMC survival, and atherosclerotic plaque stability, providing a mechanistic explanation for the association between the genetic variant and CHD risk.

Decoding the transcriptome of atherosclerotic plaque at single-cell resolution

“…The first subpopulation (Fig. 5a, red bar) has elevated expression of POSTN (osteoblasts; NE=-2.206, q= 3.60e-16) , CRTAC1 (chrondrocytes; NE=−3.22, q= 3.91e-26), TNFRSF11B (bone remodeling; NE=−0.98, q= 7.31e-06) 59 , ENG (VSMC migration; NE=0.87, q= 1.41e-13) 60 , COL4A2 and COL4A1 (cell proliferation, association with CAD; NE=−0.98, −1.03 and q= 3.17e-15, 5.68e-11, respectively) 61,62 , and a variety of interferon alpha inducible (IFI) genes which modulate numerous cellular functions from proliferation to apoptosis. SFRP5 (anti-inflammatory; NE=−4.36, q=9.84e-07) is upregulated almost exclusively in this population of VSMCs.…”

Novel locus influencing retinal venular tortuosity is also associated with risk of coronary artery disease

“…Lead SNPs associated with TortA remained significant after conditioning on the previously reported cardiovascular risk variants in COL4A2 (rs11617955[20], rs4773144[38], rs9515203[39]) ( S7 Fig. , S6 Table ).…”

Generation of functional human adipose tissue in mice from primed progenitor cells

“…Rather, extracellular matrix components, including 4 different collagen types were the predominant associated genes. One of these, COL4A1 is essential for small vessel development and pathogenic mutations cause vascular abnormalities (49)(50)(51)(52), suggesting it may have an important role in vascularization of PADS for engraftment. Also, mutations in COL3A1 give rise to vascular Ehlers-Danlos syndrome (53), indicating a role for this collagen type in vascular integrity.…”