IP3R3 Affects Pulmonary Hypertension By Mediating Mesenchymal Transition Through Mitochondrial Function

Pulmonary Arterial Hypertension（PAH）is a class of respiratory diseases characterized by abnormal arterial pressure and pulmonary arterial resistance.Persistent Hypoxic pulmonary hypertension（HPH）alters endothelial cell metabolism and transport function,and promotes thrombosis,inflammation,and increased vascular permeability.Type 3 inositol-1,4,5-trisphosphate Receptor（IP3R3）controls the release of calcium ions from the endoplasmic reticulum into the cytoplasm and mitochondria,and is involved in cell proliferation,migration,protein synthesis and permeability maintenance.In this study,we revealed the mechanism of IP3R3’s influence on the proliferation and migration of PAEC,Endothelial mesenchymal Transition（End MT）,Ca²⁺,and mitochondrial function in the development of PAH.In animal experiments,on the one hand,an animal model of pulmonary hypertension was constructed to detect the change of the expression level of IP3R3 in lung tissue;on the other hand,continuous hypoxia treatment of IP3R3^（-/-）mice induced the occurrence of PAH and detected the changes of pulmonary artery pressure and various physiological indicators.In vitro cell experiments,on the one hand,the changes in the expression level of IP3R3 after hypoxia induced PAEC were detected;on the other hand,the effects of IP3R3 on cell migration,proliferation and End MT function,as well as the effects on intracellular Ca²⁺level and mitochondrial function under hypoxia condition were detected.The results are as follows:（1）The right ventricular systolic blood pressure and right heart hypertrophy index in MCT-PH,Su Hx-PH and HPH rats were significantly higher than those in the control group,suggesting that the animal model of PAH was successfully established.Compared with the control group,the expression level of IP3R3 was significantly increased in the lung tissues of MCT-PH,Su Hx-PH and HPH rats,and the main changes were located in the pulmonary vascular endothelial cells.The right ventricular systolic pressure,right heart hypertrophy index and pulmonary vessel wall thickness of IP3R3^（-/-）mice induced by persistent hypoxia were significantly lower than those of HPH mice.（2）Hypoxia induced significantly up-regulated IP3R3 expression in human,rat and mouse PAEC;Knockdown of IP3R3 can significantly inhibit the proliferation and mesenchymal transformation of PAEC induced by hypoxia.End MT inducer TGF-β1significantly up-regulated the expression of IP3R3 and inhibited End MT and cell migration levels after IP3R3 knockdown.（3）Further explore the signaling pathway and mechanism of IP3R3 inhibition of End MT.Knockdown of IP3R3 in inducing End MT can down-regulate intracellular Ca²⁺content,inhibit End MT-induced mitochondrial damage,reduce mitochondrial ROS levels,increase mitochondrial membrane potential and mitochondrial respiratory chain complex content.In summary,IP3R3^（-/-）mice inhibit the occurrence and development of HPH,IP3R3 knockdown can inhibit hypoxy-induced PAEC functional abnormalities,and IP3R3 knockdown can improve mitochondrial function through Ca²⁺,thus inhibiting End MT process.The expression level of IP3R3 can affect the occurrence and development of PAH by altering mitochondrial function,which can be used as a potential target for prevention and treatment of PAH.