The Role Of Hippo/YAP Signaling Pathway In Regulating Angiotensin ?-induced Hypertensive Renal Injury In Mice

ObjectiveThe Hippo/YAP(yes-associated protein,YAP)signaling pathway is an evolutionarily conserved kinase cascade,playing roles in controlling organ development and tissue homeostasis by controling cell proliferation,differentation and apoptosis.YAP is the center of this network and the downstream effector of Hippo pathway and an important mediator of mechanic stress.Hippo/YAP pathway is related with many diseases,including vascular and renal fibrotic diseases.Hypertensive nephropathy is characterized with glomerular sclerosis and renal fibrosis as well as renal inflammation.Recent studies have shown that the activation of Hippo/YAP signaling pathway can promote inflammation and fibrosis,and may participate in pathogenesis of cardiovascular and renal damage.However,the role of Hippo/YAP pathway in hypertensive renal injury has not been reported.Our study investigated the role of Hippo/YAP pathway in Angiontensin(Ang)II-induced hypertension and hypertensive renal injury by using YAP inhibitor veterporfin to clarify the function and mechanism of Hippo/YAP pathway.MethodsEighteen male C57BL/6 mice(weighting 20-25 g)were randomly divided into three groups(6 in each group): normal control group,Ang II group(implanting an osmotic minipump which contains Ang II,21 days,1.1mg/kg·day),verteporfin treatment group(Ang II plus verteporfin 60 mg/kg/day intraperitoneal injection every other day)group.The systolic blood pressure(SBP)of pre-modeling,the first weekend,the second weekend and the third weekend of modeling was measured by the tail cuff method.The renal injury especially glomerulus fibrosis was examined by PAS staining,the renal interstitial fibrosis was measured by Masson staining.The expression of YAP in renal mesangial area was measured by immunofluorescence.The expression level of YAP,P-LATs,TNF?,IL-1?,MCP-1,TGF?1,Fibronectin and CTGT proteins in kidney tissue were measured by Western blot.ResultsCompared with the normal control group,the SBP,the ratio of urine protein/creatinine,glomerular sclerosis and renal fibrosis in the mice increased significantly.The treatment of verteporfin lowered SBP and alleviated proteinuria and renal structural damage significantly in Ang II group mice.Furthermore,compared with the normal control group,the fluorescence intensity of YAP in glomerular mesangial region as well as the expression leve of YAP protein in renal tissue increased and the expression level of P-LATs,the upstream signaling molecule that regulates YAP expression,decreased significantly,which suggested that Ang ? can significantly activate the Hippo/YAP signaling pathway in kidney tissue,and the verteporfin treatment can significantly reverse the changes in Hippo/YAP signaling pathway in kidney tissue induced by Ang ? in this hypertensive model.Further research shows that the administration of Ang ?can significantly upregulate the expression levels of inflammatory factors TNF-?,IL-1? and MCP-1 as well as the expression of pro-fibrotic factors TGF-?1,Fibronectin and CTGF,while verteporfin treatment can significantly reduce them.ConclusionHypertension induced by Ang ? can significantly activate the Hippo/YAP pathway in kidney tissue,and further promotes the inflammation of the kidney by up-regulating the expression levels of inflammatory factors TNF-?,IL-1? and MCP-1 and promotes renal fibrosis process by up-regulating the pro-fibrotic factor protein expression level of TGF-?1,Fibronectin and CTGF,which ultimately leads to renal structural damage and dysfunction.