Mfn2 regulates calcium homeostasis and suppresses PASMCs proliferation via interaction with IP3R3 to mitigate pulmonary arterial hypertension
R. Wang, Jie Wang, Jing Yu, Zhiqiang Li, Minfang Zhang, Yuhu Chen, Fen Liu, Dongmei Jiang, Jingfei Guo, Xiaomei Li, Yun Wu
Abstract
Pulmonary arterial hypertension (PAH) is a chronic disorder characterized by the excessive proliferation of pulmonary arterial smooth muscle cells (PASMCs). Recent studies indicate that Mitochondrial fusion protein 2 (Mfn2) maintains intracellular calcium (Ca2+) homeostasis via the mitochondria-associated endoplasmic reticulum membranes (MAMs) pathway, thereby inhibiting PASMCs proliferation and reducing pulmonary artery pressure. However, the precise mechanisms remain unclear. This study explored the roles of Mfn2 and IP3R3 in PAH progression by assessing their expression in lung tissues of a monocrotaline (MCT)-induced PAH rat model. Immunoprecipitation assays were performed to confirm the interaction between Mfn2 and IP3R3. PASMCs were treated with either silenced or overexpressed Mfn2 and exposed to TNF-ɑ to observe effects on ER stress, IP3R3 expression, mitochondrial Ca2+ transport, and mitochondrial integrity. We also evaluated the effects of 4-phenylbutyric acid (4-PBA) and cistanche phenylethanol glycosides (CPGs) on the Mfn2-IP3R3 interaction in a TNF-α-induced PAH cell model, focusing on Ca2+ transport and mitochondrial structure. Mfn2 expression was significantly down-regulated in the MCT-induced PAH rat model. Inhibition of ER stress upregulated Mfn2 expression, downregulated IP3R3 expression, increased mitochondrial Ca2+ concentration, and reduced autophagy, improving pulmonary hemodynamics and vascular remodeling. Overexpression of Mfn2 reduced ER stress, decreased IP3R3 expression, decreased mitochondrial Ca2+ transport, and restored mitochondrial integrity. Immunoprecipitation assays confirmed the interaction between Mfn2 and IP3R3. Inhibition of IP3R3 elevated Mfn2 levels, yielding similar beneficial effects as Mfn2 overexpression. 4-PBA and CPGs modulated the Mfn2-IP3R3 signaling axis, effectively inhibiting PAH progression. Mfn2 mediates mitochondrial Ca2+ transport via IP3R3, suppressing PASMCs proliferation and pulmonary vascular remodeling, underscoring Mfn2’s potential in regulating metabolic processes and vascular remodeling in PAH. These findings provide new insights for developing PAH-targeted therapeutics and establish a theoretical basis for traditional Chinese medicine in PAH prevention and treatment.