Deficiency of ZC3HC1 increases vascular smooth muscle cell migration, proliferation and neointima formation following injury

Abstract

The ZC3HC1 gene is associated with various cardiovascular traits in that its common missense variant, rs11556924-T (p.Arg363His), lowers risk of coronary artery disease (CAD) and blood pressure, but increases carotid intima-media thickness (IMT). This study was designed to determine the mechanisms by which ZC3HC1 modulates IMT using in vitro and in vivo models. We assessed the effect of the rs11556924-T allele on ZC3HC1 expression in vascular smooth muscle cells (SMCs) from 151 multi-ethnic heart transplant donors and found that rs11556924-T was significantly associated with lower ZC3HC1 expression and faster SMC migration. These results were supported by in vitro silencing experiments. At the protein level, ZC3HC1 deficiency resulted in the accumulation of cyclin B1, a key cell cycle protein. Further, transcriptome analysis revealed changes in the regulation of canonical SMC marker genes, including ACTA2, CNN1, LMOD1, and TAGLN. Pathway analysis of differentially expressed genes in SMCs secondary to ZC3HC1 knockdown showed decreased expression of genes in the cell division and cytoskeleton organization pathways. In line, primary SMCs isolated from the aortas of Zc3hc1-/- mice migrated faster and proliferated more compared to SMCs isolated from wild-type littermates, with the former also showing accumulation of cyclin B1. Neointima formation was also enhanced in Zc3hc1-/- mice in response to arterial injury mimicking restenosis. Taken together, these findings demonstrate that genetic modulation or deficiency of ZC3HC1 leads to the accumulation of cyclin B1 in SMCs and increased migration, proliferation, and injury-induced neointima formation. We further discuss and propose that a genetic variant regulating SMC proliferation may enhance IMT and early atherosclerosis progression but may be beneficial for plaque stability in advanced lesions.