虫草菌液通过增强自噬改善β-甘油磷酸诱导的血管平滑肌细胞钙化

摘要

目的 探讨冬虫夏草提取物虫草菌液(Cordyceps sinensis,CS)对高磷诱导的血管平滑肌细胞钙化的影响机制.方法 用细胞增殖与活性检测试剂盒(cell counting kit-8,CCK-8)检测CS对细胞生存活力的影响;用β-甘油磷酸(β-GP,10 mmol/L))建立大鼠血管平滑肌细胞(VSMC)钙化模型,加入CS(10 mg/L)、自噬抑制剂3-甲基腺嘌呤(3-methyladenine,3-MA,5 mmol/L)及一磷酸腺苷(AMP)活化的蛋白激酶(AMPK)抑制剂化合物C(CC,10 μmol/L)进行干预,实验分为5组:对照组(Ctrl)、β-GP组、β-GP+CS组、3-MA+β-GP+CS组、CC+β-GP+CS组.通过茜素红S染色及钙测定试剂盒检测各组细胞钙沉积量;透射电镜观察VSMC内自噬体的形成;免疫荧光检测细胞质内微管相关蛋白1轻链3(LC3)的表达;Western印迹法检测血管平滑肌标志物α-SMA蛋白、成骨指标Runx2、自噬相关蛋白LC3Ⅱ/LC3Ⅰ和Beclin1及AMPK/雷帕霉素靶蛋白(mTOR)信号通路蛋白.结果 虫草菌液能使高磷环境中血管平滑肌细胞的自噬体、LC3荧光点状聚集及LC3Ⅱ/LC3Ⅰ、Beclin1、α-SMA、磷酸化(p)-AMPK蛋白表达增多,Runx2、p-mTOR蛋白表达及钙沉积减少(均P＜0.01).用3-MA抑制自噬后,β-GP+CS环境中的血管平滑肌细胞α-SMA蛋白表达减少(P＜0.01),Runx2蛋白表达及钙沉积增多(均P＜0.01),提示虫草菌液是通过激活自噬减轻了β-GP诱导的血管平滑肌细胞的钙化.用CC抑制AMPK/mTOR信号通路后,β-GP+CS组的血管平滑肌细胞的p-AMPK蛋白表达明显减少(P＜0.01),且LC3Ⅱ/LC3 Ⅰ、Beclin1、α-SMA蛋白表达量及自噬体、LC3荧光点状聚集也减少,p-mTOR、Runx2蛋白表达量及钙沉积增多(均P＜0.01),提示虫草菌液是通过激活依赖AMPK/mTOR信号通路的自噬而减轻了β-GP诱导的血管平滑肌细胞的钙化.结论 虫草菌液能有效减轻高磷诱导的血管平滑肌细胞钙化,其机制可能是通过激活AMPK/mTOR信号通路增强自噬.%Objective To investigate the influence mechanism of Cordyceps sinensis (CS) on β-glycerophosphate-induced vascular smooth muscle cell (VSMC) calcification.Methods The effect of CS on VSMC cell viability was detected by CCK-8.The cellular models of rat VSMC calcification were established by treating with β-glycerophosphate (β-GP,10 mmol/L);then CS (10 mg/L),autophagy inhibitor 3-methyladenine (3-MA,5 mmol/L),and AMPK inhibitor compound C (CC,10 μmol/L) were added to the cell cultures.There were a total of 5 experiment groups:VSMC cultured in normal medium (Control),VSMC treated with β-GP,VSMC treated with β-GP and CS,VSMC treated with 3-MA,β-GP and CS,and VSMC treated with CC,β-GP and CS.The calcium nodules and calcium content were examined with alizarin red S staining and the O-cresolphthaleincomplexone method,respectively.The autophagosomes within the VSMC were observed using transmission electron microscope (TEM).Immunofluorescence showed the accumulation of microtubule-associated protein 1 light chain 3 (LC3) puncta.In addition,levels of osteogenic related proteins,autophagy related proteins,and AMPK/mTOR pathway related proteins were evaluated by Western blotting.Results CS increased the number of autophagosomes and the accumulation of LC3 puncta within VSMC.It also upregulated the protein levels of LC3 Ⅱ/LC3 Ⅰ,beclin1,α-SMA,and p-AMPK;whereas,the protein levels of Runx2 and p-mTOR,as well as calcium nodules and calcium content were reduced (all P ＜ 0.01).When the cells were pretreated with 3-MA before treating with β-GP and CS,the autophagosomes,accumulation of LC3 puncta,and protein levels of LC3 Ⅱ/LC3 Ⅰ,beclinl,and α-SMA were decreased (all P ＜ 0.01);however,the protein level of Runx2,and the calcium nodules and calcium content were increased (all P ＜ 0.01).Nevertheless,when the cells were pretreated with CC before giving β-GP and CS,the autophagosomes,the accumulation of LC3 puncta,and the expression levels of p-AMPK,LC3 Ⅱ/LC3 Ⅰ,beclin1,and α-SMA were significantly down-regulated (all P ＜ 0.01);whereas,the expression levels of Runx2 and p-mTOR,as well as calcium nodules and calcium content were increased (all P ＜ 0.01).Conclusions CS can effectively alleviate β-GP-induced VSMC calcification,which may be due to the activation of autophagy by AMPK/mTOR signaling pathway.