The Function And Mechanism Of Endothelial MTORC1 In Relaxation Dysfunction And Hypertension

Hypertension is a chronic disease state in which the blood pressure in the arteries is persistently elevated.Hypertension is a major risk factor for coronary artery disease,stroke,heart failure,atrial fibrillation,peripheral vascular disease,vision loss,chronic kidney disease and dementia.Vascular endothelial cells?EC?maintain homeostasis and stabilize vascular tone in the autonomic and paracrine manner.Therefore,intracellular vascular dysfunction is closely related to hypertension.Rapamycin is an inhibitor of mTORC1,clinically used as immunosuppressive drugs.However,long-term use of rapamycin causes elevated arterial pressure.In recent years,the study found that rapamycin can lead to hypertension by inhibiting the mTORC1activity,but its specific pathogenesis is not yet clear.The purpose of this study is to reveal the molecular mechanism of rapamycin leading to endothelial dysfunction and hypertension,and provide a theoretical basis for the clinical use of rapamycin.EC-Raptor^KD mice and EC-Raptor^floxlox mice were given Angiotensin??Ang??slow-release pump for 4 weeks,respectively.Tail-cuff method was used to measure the changes of arterial blood pressure in mice.EC-Raptor^KD mice resulted in an increase in SBP,DBP and MBP.After 4 weeks of Ang?treatment,EC-Raptor^KDD mice resulted in severe myocardial interstitial fibrosis and perivascular fibrosis.In order to clarify the specific mechanism of EC-Raptor^KD induced high blood pressure in mice,we isolated the secondary mesenteric artery of EC-Raptor^KD mice and EC-Raptor^flox mice,respectively,indicating that EC dependent relaxation dysfunction leads to increased arterial blood pressure in EC-Raptor^KD mice by microvascular tension test.To further confirm that Raptor specifically affects endothelial cell function by COX-1 or COX-2,COX-1 and COX-2-specific inhibitors?SC560/NS-398?were used to treat secondary mesenteric arteries,the results showed that Raptor affected relaxation dysfunction by the regulation of COX-2.Next,we analyzed the changes of plasma AA metabolites in EC-Raptor^KD mice and EC-Raptor^floxlox mice using LC-MS/MS,demonstrating that the COX metabolic pathway has changed significantly in EC-Raptor^KD mice.In vitro cell experiments,RNAi knockdown of Raptor EC,the cell culture medium and cells were collected for LC-MS/MS analysis,the COX metabolic pathway has changed significantly after knockdown of Raptor.EC-Raptor^KD mice and RNAi knockdown of Raptor EC suggest that mTORC1 affect the synthesis of PGE₂ in endothelial cells.In summary:The present study shows that inhibition of Raptor activity,the core component of mTORC1,affected the activity of COX-2 protein and decreased the production of PGE₂,eventually induced EC dependent relaxation dysfunction leading to hypertension.The mechanism of rapamycin study provides a theoretical basis for the specific medication as well as a potential target for the treatment of related diseases.