S100A4 plays a role in mouse arterial smooth muscle cell motility. Implication for intimal thickening formation.

Abstract

During atherosclerosis, smooth muscle cells (SMCs) migrate and accumulate in the intima, where they switch from a contractile to a synthetic phenotype. This process is associated with decreased expression or loss of contractile proteins, such as -smooth muscle actin (-SMA) or smooth muscle myosin heavy chains (SMMHCs). We previously demonstrated that S100A4, a small calcium-binding protein, which exhibits intra- and extracellular functions, is a marker of the synthetic SMC phenotype. We have recently shown that neutralization of extracellular S100A4 in an ApoE knockout (KO) mouse model with established atherosclerotic lesions decreased the overall atherosclerotic burden. To explore the role of S100A4 in the accumulation of SMCs in the intima, we induced intimal thickening (IT) formation in full S100A4 knockout (KO) and wild type (WT) mice by completely ligating the left common carotid artery. With this model, we generated SMC-rich lesions. The deletion of S100A4 did not influence the size of the IT, neither its composition, as assessed by the expression of -SMA and SMMHCs in S100A4 KO animals compared with WT animals, 4 weeks after ligation. Using primary cells isolated from both strains, we demonstrated that S100A4 KO SMCs were less prone to migrate than WT SMCs but they did not differ in their proliferative capacity. Our results indicate that S100A4 plays a role in SMC motility in vitro but its deletion does not influence IT formation in the mouse carotid artery ligation model.