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

RationaleThe ZC3HC1 gene has been linked to various cardiovascular traits. One variant, rs11556924-T, has been found to lower the risk of coronary artery disease (CAD) and blood pressure but increases carotid intima-media thickness (IMT). ObjectiveThis study aimed to determine how ZC3HC1 affects IMT using in vitro and in vivo models. We analyzed the effect of the rs11556924-T allele on ZC3HC1 expression in vascular smooth muscle cells (SMCs) from 151 multi-ethnic heart transplant donors. The results showed that rs11556924-T was associated with lower ZC3HC1 expression and faster SMC migration. ZC3HC1 knockdown (KD) experiments supported these findings, showing increased migration and proliferation. Mechanistically ZC3HC1 KD led to decreased expression of contractile marker genes and the accumulation of cyclin B1, a key cell cycle protein. Pathway analysis of differentially expressed genes between ZC3HC1 KD and controls SMCs showed decreased expression of genes in the cell division and cytoskeleton organization pathways, as well as higher expression of genes involved in extracellular matrix organization and cytokine-mediated signaling. To validate these findings in vivo, we generated and characterized knockout (Zc3hc1-/-) mice. These mice had enhanced neointima formation in response to arterial injury and faster SMCs migration ability. However, complete loss of Zc3hc1 led to a significant reduction in SMC proliferation and lower cyclin B1 protein level. In addition, immunostaining and confocal microscopy demonstrated, for the first time, that ZC3HC1 and Cyclin B1 were located at the cleavage furrow during mitotic progression of SMCs. ConclusionsCollectively, our study suggests that lower ZC3HC1/NIPA level leads to increased SMC migration and neointima formation. Moreover, we proposed a biphasic role of NIPA in proliferation. Lower levels of NIPA promote SMC proliferation, while complete loss of NIPA hampers cell division and abrogates proliferation.