FUNDC1/USP15/Drp1 ameliorated TNF-α-induced pulmonary artery endothelial cell proliferation by regulating mitochondrial dynamics.

Mitochondrial dysfunction in pulmonary artery endothelial cells (PAECs) is related to the pathogenesis of pulmonary hypertension (PH). The mitochondrial receptor protein FUN14 domain containing 1 (FUNDC1) was found to be involved in pulmonary artery smooth muscle cell proliferation in PH. However, its role in PAECs remains unclear. We investigated FUNDC1 expression in the pulmonary artery endothelium in both monocrotaline-induced animal models and TNF-α-stimulated cell models. Additionally, the effect of FUNDC1 on PAECs proliferation and its possible mechanism were also investigated. We observed decreased FUNDC1 protein levels in animals and in vitro in PAECs. FUNDC1 deficiency in PAECs upregulated the expression of the deubiquitination enzyme ubiquitin-specific peptidase 15 (USP15), enhanced dynamin-related protein1 (Drp1)-mediated mitochondrial division, and increased mitochondrial ROS levels via the deubiquitination of Drp1. Additionally, FUNDC1 deficiency increased aerobic glycolysis, the production of ATP and lactic acid, and glucose uptake. FUNDC1 overexpression inhibited PAECs proliferation. Moreover, FUNDC1 overexpression in combination with a mitochondrial division or aerobic glycolysis inhibitor enhanced its inhibitory effect on cell proliferation. Our study findings suggest that FUNDC1 deficiency induced by inflammation can promote PAECs proliferation by regulating mitochondrial dynamics and cell energy metabolism via the USP15/Drp1 pathway.