MiR-125a regulates mitochondrial homeostasis through targeting mitofusin 1 to control hypoxic pulmonary vascular remodeling.

Abnormal pulmonary arterial smooth muscle cells (PASMCs) proliferation is an important pathological process in hypoxic pulmonary arterial hypertension. Mitochondrial dynamics and quality control have a central role in the maintenance of the cell proliferation-apoptosis balance. However, the molecular mechanism is still unknown. We used hypoxic animal models, cell biology, and molecular biology to determine the effect of mitofusin 1 (Mfn1) on hypoxia-mediated PASMCs mitochondrial homeostasis. We found that Mfn1 expression was increased in hypoxia, which was crucial for hypoxia-induced mitochondrial dysfunction and smooth muscle cell proliferation as well as hypoxia-stimulated cell-cycle transition from the G0/G1 phase to S phase. Subsequently, we studied the role of microRNAs in mitochondrial function associated with PASMC proliferation under hypoxic conditions. The promotive effect of Mfn1 on pulmonary vascular remodeling was alleviated in the presence of miR-125a agomir, and miR-125a antagomir mimicked the hypoxic damage effects to mitochondrial homeostasis. Moreover, in vivo and in vitro treatment with miR-125a agomir protected the pulmonary vessels from mitochondrial dysfunction and abnormal remodeling. In the present study, we determined that mitochondrial homeostasis, particularly Mfn1, played an important role in PASMCs proliferation. MiR-125a, an important underlying factor, which inhibited Mfn1 expression and decreased PASMCs disordered growth during hypoxia. These results provide a theoretical basis for the prevention and treatment of pulmonary vascular remodeling. KEY MESSAGES: Hypoxia leads to upregulation of mitofusin 1 (Mfn1) both in vivo and in vitro. Mfn1 is involved in hypoxia-induced PASMCs proliferation. Mfn1-mediated mitochondrial homeostasis is regulated by miR-125a. MiR-125a plays a role in PASMCs oxidative phosphorylation and glycolysis.