Regulatory effects of Prohibitin 1 on proliferation and apoptosis of pulmonary arterial smooth muscle cells in monocrotaline-induced PAH rats.

Background: Pulmonary arterial hypertension (PAH) is a severe pulmonary vascular disease characterized by unbalanced proliferation and apoptosis of pulmonary arterial smooth muscle cells (PASMCs). Prohibitin 1 (PHB1) is known for its significant anti-proliferative activity. However, the role of PHB1 in PASMCs and PAH have not been elucidated.

Methods: Monocrotaline (MCT 60 mg/kg) was used to build a PAH model in SD rats. Right ventricular systolic pressure (RVSP) and right ventricle (RV) hypertrophy were measured. Morphology of pulmonary vessels was observed by Hematoxylin-Eosin (HE) staining. Expression of PHB1 in pulmonary arteries and PASMCs was determinated by immunoblot and immunofluorescence. Cell proliferation was detected by CCK8 and EDU when PASMCs were stimulated by PDGF-BB (20 ng/mL). Furthermore, siRNA for PHB1 and Akt inhibitor were conducted to investigate the mechanism behind the role of PHB1 and AKT signaling pathway in PASMCs proliferation and apoptosis.

Results: The protein expression of PHB1 in PAH rats lung tissue was significantly up-regulated accompanied by elevated RVSP and enhanced RV hypertrophy. Immunohistochemistry showed that PHB1 was mainly localized in the pulmonary vascular smooth muscle layer. PDGF-BB significantly up-regulated the expression of PHB1 in rat primary PASMCs in a time- and dose-dependent manner. After PHB1 knock down, PASMCs proliferation was significantly suppressed while apoptosis was significantly recovered. Meanwhile the level of proliferating cell nuclear antigen (PCNA) and P-Akt were significantly down-regulated. Perifosine (Akt inhibitor) also significantly inhibit proliferation of PASMCs.

Conclusion: PHB1 contributes to pulmonary vascular remodeling by accelerating proliferation of PASMCs which involves AKT phosphorylation.