SM22α Phosphorylation: A Novel Mechanism of Activation of PKCδ‐P47phox Axis and ROS Production in VSMCs

Abstract

Smooth muscle 22 alpha (SM22α), an actin‐binding protein abundant in vascular smooth muscle cells (VSMCs), is downregulated in atherosclerosis. The recent study indicates that disruption of SM22 promotes arterial inflammation through activation of reactive oxygen species (ROS). However, the molecular mechanisms by which SM22α controls the production of ROS have not been characterized. We investigated the effect of SM22α disruption on ROS production. ROS was detected using dihydroethidium for superoxide. The expression of proteins was detected by Western Blotting after transfection with small interfering RNA. We showed that down‐regulation and phosphorylation of SM22α were associated with angiotensin (Ang) II‐induced increase in ROS production in VSMCs. The phosphorylation of SM22α at Serine 181 was increased in an AT1R‐PKCδ pathway‐dependent manner in VSMCs upon Ang II. Phosphorylated SM22α facilitated Ang II‐inducted ROS production via activation of PKCδ‐p47phox axis through release of PKCδ and actin dynamics in VSMCs and was associated with intimal thickening. These results indicate that disruption of SM22α plays pivot roles in regulation of ROS production in VSMCs, and may be a potential target for the development of new therapeutics for vascular diseases..Source of fundings: This study was supported by the National Natural Science Foundation of China (31071003).