MCU-dependent mitochondrial calcium uptake-induced mitophagy contributes to apelin-13-stimulated VSMCs proliferation.

Apelin is an endogenous ligand of the G protein-coupled receptor APJ. Both apelin and APJ receptors, which are expressed in vascular smooth muscle cells (VSMCs), play important roles in the cardiovascular system. Our previous studies researches indicated that mitophagy mediated apelin-13-induced VSMCs proliferation. However, little is known about how apelin-13 regulates mitophagy to participate in VSMC proliferation. The results of the present study demonstrated that mitochondrial calcium uniporter (MCU) uptake-dependent mitochondrial calcium-induced mitophagy is involved in apelin-13-induced VSMCs proliferation. Apelin-13 promoted the expression of MCU which increases mitochondrial calcium uptake. Apelin-13-induced MCU-dependent mitochondrial calcium uptake further increased mitochondrial ROS (mtROS) concentrations and promoted mitophagy, which can be evidenced through the upregulation of the Dynamin-related protein 1(Drp1), PTEN-induced kinase 1 (PINK1), and Parkin. The clearance of mtROS by Mito-TEMPO significantly reversed apelin-13-induced mitophagy. Moreover, both the Drp1 inhibitor mdivi-1 and siRNA-Drp1 inhibited apelin-13-induced mitophagy. Furthermore, the APJ receptor antagonist F13A, MCU inhibitor Ru360, mitochondria-targeted antioxidant Mito-TEMPO, Drp1 inhibitor Mdivi-1, siRNA-Drp1, siRNA-PINK1, and siRNA-Parkin inhibited the proliferation of VSMCs induced by apelin-13. In ApoE mice, intraperitoneal administration of apelin-13 induced the expression of MCU, Drp1, PINK1, Parkin, and α-SMA and increased atherosclerotic plaque lesions. However, F13A and Ru360 decreased the expression of MCU, Drp1, PINK1, Parkin, and α-SMA and reduced atherosclerotic plaque lesions in ApoE mice injected with apelin-13. Collectively, our results demonstrate that MCU-dependent mitochondrial calcium uptake-induced mitophagy is involved in apelin-13-stimulated VSMCs proliferation.