MicroRNA-136 Promotes Vascular Muscle Cell Proliferation Through the ERK1/2 Pathway by Targeting PPP2R2A in Atherosclerosis

Aberrant proliferation of vascular smooth muscle cells [VSMCs] is implicated in the pathogenesis of vascular pathologies such as atherosclerosis and restenosis. Accumulating evidences have revealed that microRNAs are involved in cell proliferation in various pathological conditions. In the present study, we showed that miR-136 was up regulated in human coronary atherosclerotic plaques when compared with normal coronary artery tissues. Moreover, miR-136 levels were up regulated in proliferative vascular smooth muscle cells induced by platelet-derived growth factor [PDGF] or serum. In cultured VSMCs, over expression of miR-136 stimulated cell proliferation. PPP2R2A was proved to be the direct target gene of miR-136 and knockdown of PPP2R2A had a proliferative effect on VSMCs. miR-136-induced PPP2R2A down-regulation was accompanied by increased expression of ERK1/2 phosphorylation. Inhibition of ERK1/2 abolished the effect of miR-136 and knockdown of PPP2R2A on VSMCs proliferation. In summary, aberrant miR-136 up regulation in atherosclerosis contributes to abnormal VSMC proliferation through suppressing the ERK1/2 pathway by targeting PPP2R2A. Our study also suggested that specific modulation of miR-136 in human VSMCs may provide a potential approach for the treatment of atherosclerosis.