Salidroside Inhibits Clinorotation‐induced Apoptosis in Pulmonary Microvascular Endothelial Cells by regulating signaling pathway of Endoplasmic reticulum stress

Abstract

ObjectiveMicrogravity or simulated microgravity induces dysfunction of endothelium. We have previously demonstrated that clinorotation induces apoptosis in microvascular endothelial cells. Salidroside(Sal), one of main active ingredients extracted from the root of Rhodiola rosea, has been documented to have potent antiapoptotic effects on some cells. The present study investigated whether salidroside inhibited clinorotation‐ induced apoptosis in microvascular endothelial cells by regulating the signaling pathway of endoplasmic reticulum(ER) stress.MethodsHuman pulmonary microvascular endothelial cells(HPMECs) were divided into control group, clinorotation group, clinorotation+Sal and clinorotation+Sal+ LY294002 pretreatment groups. Microgravity was simulated by clinorotation. After 72h clinorotation, the apoptotic rate of HPMECs was detected by TUENL assay and JC‐1 staining. The protein expressions of PI3K, Akt, Bcl‐2, Bax, caspase‐3 and caspase‐9 were determined by Western blot. Meanwhile, the ER stress related proteins such as GRP78, CHOP, IRE1a and ATF6 were measured.ResultsTUNEL assay, together with JC‐1 staining indicated that 72h clinorotation significantly induced apoptosis in HPMECs, which was reversed by salidroside treatment. Clinorotation also decreased the protein expression of PI3K, Bcl‐2 and phospho‐Akt level, increased the apoptosis related protein expression of Bax, caspase 3 and caspase 9. Meanwhile, Clinorotation increased the ER sensors protein expression of GRP78, CHOP, IRE1a and ATF6. Pretreatment with salidroside reversed the changes of these protein expression induced by 72h clinorotation, however, the protective effects of salidroside were reversed by inhibitor of PI3K/Akt, LY294002.ConclusionOur results suggested that the apoptosis of HPMECs induced by 72h clinorotation can be alleviated by pretreatment of salidroside. The protective effects of salidroside on HPMECs apoptosis may come from the upregulation of PI3K/Akt signal pathway and downregulation of ER stress pathway.Support or Funding InformationFunded by the Defense Medical Fund of China (Grant No. 06Z048) and State key lab of space medicine fundamentals and application, China Astronaut Research and Training Center (grant No. SMFA14B01).