A genetic analysis identified zinc finger E-box binding homeobox 2 (ZEB2) as a variant that affects plaque vulnerability and may have implications for or be a potential drug target for coronary artery disease (CAD). The findings were published in Circulation.
For the study, researchers used a CRISPR-Cas-9 genome and epigenome editing approach to identify causal genes for CAD. A single-cell epigenetic and transcriptomic profiling approach of a murine model and human coronary artery smooth muscle cells were used to assess cellular and molecular mechanisms of potential causal genes.
Almost a decade ago, a genetic locus at 2q22.3 was associated with CAD risk. This region has been found to be highly conserved, even to lower vertebrates, and has several large distant haploblocks that are tightly linked with the lead single nucleotide polymorphism (SNP) for CAD risk.
The closest gene (>600,000 bp distant) to this locus is ZEB2. Epigenetic markers suggest the region may be functional enhancers for ZEB2 coupled with the fact the chromatin of the region has evolutionarily conserved looping structures.
SNPs associated with CAD were observed to influence the expression of ZEB2, but not other nearby genes. The alleles that increased ZEB2 expression were associated with decreased CAD risk.
Using a gene-editing approach, altering the enhancer of ZEB2 was observed to decrease ZEB2 expression.
Single cell experiments found that macrophages and fibroblasts expressed Zeb2 in the absence of atherosclerosis. In addition, Zeb2 expression was activated in the process of atherosclerotic plaque development. Similar patterns were observed among cells isolated from humans.
In mice with Zeb2 loss, cells from the aortic root were observed to have impaired transition from smooth muscle cells to a fibroblast-like fibromyocyte phenotype, instead accelerating development of an endochondral-like “chondromyocyte” phenotype. These effects appeared to be caused by chromatin remodeling.
In cultured primary human coronary artery smooth muscle cells, loss of ZEB2 increased expression of mature smooth muscle cell genes and decreased expression of fibroblast-like fibromyocyte genes. Overexpression caused an opposite effect.
Together, these observations indicated that ZEB2 alters Notch and TGFb signaling by obviating accessibility through epigenetic changes.
“These observations mirror both decades old and emerging human epidemiologic data whereby a variety of higher risk plaque features, rather than plaque size or lumen narrowing, are much better predictors of myocardial infarction,” the study authors wrote. “Thus, a convergence of different types of information points to the critical importance of utilizing finer molecular phenotyping at higher resolution to better understand the biology that influences risk for vascular events related to atherosclerosis.”
Cheng P, Wirka RC, Clarke LS, et al. ZEB2 shapes the epigenetic landscape of atherosclerosis. Circulation. Published online January 6, 2022. doi:10.1161/CIRCULATIONAHA.121.057789