Silence of Insulin-Like Growth Factor 2 mRNA-Binding Protein 1 Prevents Vascular Smooth Muscle Cells Proliferation via Nuclear Factor of Activated T Cells Isoform-3/Ca2+/Calmodulin Pathway

Abstract

Increased proliferation of vascular smooth muscle cells (VSMCs) contributes to the pathogenesis of atherosclerosis (AS), and the insulin like growth factor 2 (IGF2) is involved in AS through effects on VSMCs growth and migration. The IGF2 mRNA-binding protein 1(IGF2BP1) is a secreted protein that can bind to IGF2 and regulate its localization, however, whether IGF2BP1 could regulate VSMCs proliferation remains to be elucidated. This study aimed to investigate the role of IGF2BP1 in VSMCs proliferation and uncover the potential mechanism. Primary human aortic VSMCs that transfected with or without shRNA-IGF2BP1 were stimulated by platelet-derived growth factor-BB (PDGF-BB), and then cell proliferation, intracellular Ca2+ level, cell apoptosis and the expression of IGF2BP1, calmodulin (CaM) and cell cycle-related proteins were detected. RNA pull down assay was used to determine the interaction between IGF2BP1 and nuclear factor of activated T cells isoform-3 (NFATc3). We found that PDGF-BB promoted cell proliferation and enhanced IGF2BP1 protein expression in a concentration-dependent manner. The 10 μg/L PDGF-BB significantly increased intracellular Ca2+ level, NFATc3, CaM and calcineurin A protein expression, TUNEL-positive cells, and the expression of cell cycle-related proteins cyclin D1/E1/B1. However, knockdown of IGF2BP1 significantly blunted all these effects induced by PDGF-BB. In addition, IGF2BP1 could bind to NFATc3 RNA. Collectively, knockdown of IGF2BP1 could inhibit PDGFBB- induced VSMCs proliferation via targeting NFATc3/Ca2+/calmodulin pathway and disturbing the effect of NFATc3/ on cell cycle.