Salusin-? Promotes Lipoprotein Lipase Expression Via MiR93-5p/LKB1/AMPK/TBP Pathway In Vascular Smooth Muscle Cells

[Background and Objective] Atherosclerosis is the most dangerous disease in the world,and the pathogenesis is very complex.The specific mechanism has not been clarified.Accumulating studies have confirmed that lipid metabolism disorders are risk factors for atherosclerosis.Lipoprotein lipase is the major secreted triglyceride(TG)hydrolysis enzyme that hydrolyzes triglyceride-rich lipoproteins(TRL)to liberate fatty acids.More and more studies have confirmed that LPL plays an important role in atherosclerosis.Therefore,identification of factors that affect the expression of LPL has become a new avenue to develop effective therapeutic interventions of atherosclerosis.Salusins are endogenous bioactive peptides that are identified as vital factors in the cardiovascular system.Salusin-? was reported to decrease the progression of atherosclerosis.Several lines of evidence suggested that Salusin-? was also involved in the prevention of macrophage foam cell formation by down-regulating acetyl-coenzyme,the acetyltransferase.Therefore,Salusin-? acts as a candidate biomarker for atherosclerosis and may have a therapeutic potential for atherosclerotic cardiovascular disease prevention.However,the detailed underlying mechanisms,especially the potential effects of Salusin-? on LPL expression are unknown.Therefore,our study is to explore the role of Salusin-? on LPL expression and the potential mechanism in VSMCs.[Methods] The effects of Salusin-? on the expression of LPL were detected using qPCR and Western Blot.Meanwhile,the role of Salusin-?in the combination of transcription factors TBP with LPL promoter were detected by Chromatin Immunoprecipitation.When the cells were treated by siRNA LKB1 and Compound C,which are the activation agents of AMPK,the levels of LKB1,AMPK,TBP and LPL were tested by qPCR and Western to verify whether Salusin-? increased the expression of LPL through LKB1/AMPK pathway.The relationship between LKB1 and miR93-5p was analyzedby Bioinformatics,qPCR and Western Blot.When the cells were treated with miR93-5p mimic,the levels of LKB1,AMPK,TBP and LPL were tested by qPCR or Western to verify whether Salusin-? influenced on the expression of LPL through the miR93-5p.[Results] We found that Salusin-? increased the levels of LPL by both concentration-and time-dependent manners.Salusin-? increased the levels of TBP and confirmed its recruitment to LPL promoter,consequently up-regulating the expression of LPL by Chromatin immunoprecipitation.Besides,Salusin-? activates the AMP-activated protein kinase(AMPK)signals pathway and AMPK may be one of the upstream signals of the TBP in vascular smooth muscle cells(VSMCs).Furthermore,miR93-5p can directly bind to the 3'UTR of liver kinase B1(LKB1)gene,which inhibited the AMPK pathway.Finally,miR93-5p mimic transfection significantly reduced LKB1 expression,decreased AMPK phosphorylation,and down-regulated TBP and LPL expression,which were reversed in response to treatment with Salusin-?.[Conclusion] Salusin-? reduces the levels of miR95-5p,activates LKB1/AMPK pathway and promotes the expression of TBP to increase LPL expression in VSMCs.