The Protective Effect And Mechanism Of SIRT1 Deacetylated Beclin1 Mediated Autophagy Activationin Sepsis-induced Acute Kidney Injury

Introduction:Sepsis is a syndrome of physiologic,pathologic,and biochemical abnormalities induced by infection,which is one of the most common causes of death among hospitalized patients in the intensive care unit(ICU).Acute kidney injury(AKI)is a frequent complication in sepsis,namely sepsis-induced acute kidney injury(SAKI).SAKI often contributes to the morbidity and mortality of sepsis patients.At present,no ideal therapy is generally accepted to treat SAKI,and effective treatments are especially required.Thus,fully understanding the pathogenesis of SAKI is a top priority.Our previous research found that SIRT1 activation can attenuate SAKI.SIRT1 can upregulate autophagy-related proteins(Atg5,7,and LC3,).Of note,SIRT1 upregulation deacetylated Beclinl protein but no other candidate proteins in SAKI.It has been reported that the unique acetylated lysine sites of Beclin1 are K430 and K437.SIRT1 deacetylates Beclinl at these sites,promoting autophagy and inhibiting tumor growth.However,it is rarely reported about the mechanism of SIRT1 regulating the acetylation level of Beclinl,especially in SAKI.Therefore,based on previous studies,we had explored the significance of SIRT1 regulated the acetylation level of Beclinl to find out the specific mechanism and protective role of SIRT1 in SAKI.We hope it can provide a new theoretical basis for the prophylaxis and treatment about SAKI.Method:This study constructed of cecal ligation and puncure(CLP)-induced sepsis of animal model and LPS-induced inflammation of cell model,and used pathological staining,TUNEL staining,transmission electron microscopy,immunoblotting,plasmid and adenovirus overexpression,mRFP-GPF-LC3 adenovirus,immunoprecipitation,etc.,to observing of SIRT1 in regulating the acetylation level of Beclinl which mediates the autophagy in SAKI.Result:1.Sepsis induced kidney tubular injury in a time-dependent manner.Animal experiments had showed that tubular injury continued to worsen in CLP-induced sepsis mice.During cytology experiments,HK-2 cell viability decreased in a time-dependent and concentration-dependent manner with LPS stimulation.2.Autophagy is activated in response to SAKI.The levels of autophagy both observed in the renal cortex of CLP-induced sepsis mice and in the LPS-stimulated HK-2 cell inflammatory model had reached the peak at 8 h after stimulation and then back to basal levels.Meanwhile,a large number of apoptosis occurred at 12 h and 24 h after CLP.3.By using autophagy agonists and inhibitors to observe the pathological result on animal and cell viability analysis,it has shown that activation of autophagy can improve renal injury after sepsis.4.By using agonists and inhibitors of SIRT1 in animal models and using the overexpression of SIRT1 in cell models had demonstrated that activation of SIRT1 can induce an increasing level of autophagy in renal tubular epithelial cells following sepsis.5.SIRT1 deacetylates Beclinl to activate autophagy in renal tubular epithelial cells(RTECs).SIRT1 upregulation deacetylated Beclinl protein but no other candidate proteins in SAKI.The interaction between SIRT1 and Beclin1 protein have been found in the HK-2 cell of inflammatory model and SIRT1 can deatylate Beclin1.In addition,Beclinl deacetylated by SIRT1 at lysine 430 and 437,which increase the level of autophagy in HK-2 cells of inflammatory model.6.Activation of SIRT1 protect against renal injury in CLP-induced septic mice.In our study,both natural plant polyphenol extract resveratrol and polydatin attenuate SAKI due to SIRT1 activation.Conclusion:1.Autophagy is transiently induced followed by severe inhibition in the pathogenesis of SAKI and autophagy upregulation can attenuate SAKI.2.SIRT1 activation attenuated SAKI is associated with autophagy upregulation.SIRT1 deacetylates the K430 and K437 lysine sites of Belcinl protein,which subsequently promotes autophagy and ameliorates SAKI.