PI3K/Akt对饱和脂肪酸诱导肝细胞脂变内质网应激及脂性凋亡的影响  

Role of PI3K/Akt pathway in endoplasmic reticulum stress and apoptosis induced by saturated fatty acid in human steatotic hepatocytes

作　　者：瞿梅[1] 沈薇[1] 

机构地区：[1]重庆医科大学附属第二医院消化内科,400010

出　　处：《中华肝脏病杂志》2015年第3期194-199,共6页Chinese Journal of Hepatology

基　　金：重庆市卫生局重点课题（2012-1-033）;国家自然科学基金（81270494）

摘　　要：目的 探讨磷脂酰肌醇-3激酶（PI3K）/蛋白激酶B（Akt）对饱和脂肪酸诱导脂变肝细胞内质网应激UPR（unfolded protein response）和非UPR信号途径的调控以及对脂变肝细胞凋亡的影响. 方法 采用软脂酸钠诱导建立L02、HepG2细胞脂变模型,将细胞均分为空白对照组（普通培养基培养）,脂变模型组（软脂酸钠）和抑制剂干预组（软脂酸钠加PI3K/Akt抑制剂LY294002）.流式细胞术检测细胞凋亡;Western blot检测葡萄糖调节蛋白（GRP） 78、PI3K、p-PI3K、Akt、p-Akt、C/EBP同源蛋白（CHOP）和Bcl-2相关X蛋白（Bax）表达水平.多个样本均数的比较采用单因素方差分析,两个样本均数的比较采用t检验. 结果 流式细胞术检测结果显示,L02细胞24h及48h对照组、模型组、干预组凋亡率分别为4.41％±0.78％对比6.01％±1.49％对比19.50％±2.53％,12.56％±2.78％对比29.72％±6.39％对比44.60％±4.17％.HepG2细胞24h及48h对照组、模型组、干预组凋亡率分别为11.16％±1.15％对比17.50％±6.83％对比30.41％±3.62％,22.37％±1.24％对比33.85％±5.79％对比48.56％±4.21％,软脂酸钠诱导脂变肝细胞发生了凋亡,LY294002处理后增加软脂酸钠诱导的脂变肝细胞的凋亡,各时间点（24h、48 h）干预组的凋亡率与对应模型组相比,差异有统计学意义（P＜0.05）.Western blot结果显示模型组肝细胞内GRP78表达明显上调,表明软脂酸钠诱导脂变肝细胞发生了内质网应激,进一步观察发现软脂酸钠诱导肝细胞内质网应激UPR、非UPR信号途径中CHOP、Bax的表达且激活了PI3K/Akt通路,LY294002抑制PI3K/Akt通路后,进一步增加了CHOP、Bax蛋白表达. 结论 PI3K/Akt通路可能通过影响饱和脂肪酸诱导脂变肝细胞内质网应激UPR和非UPR信号途径中CHOP和Bax蛋白表达来调控脂性凋亡.Objective To investigate the roles of PI3K/Akt signaling in the unfolded protein response （UPR） and non-UPR signaling pathways of endoplasmic reticulum stress and apoptosis in hepatocytes under conditions of saturated fatty acid-induced steatosis.Methods A steatosis model of hepatocytes （L02 cell and HepG2 cell line） was induced by palmitate sodium saturated fatty acids.The hepatocytes were divided into normal control group,experimental group （treated with palmitate sodium） and intervention group （treated with palmitate sodium and LY294002,a PI3K/Akt inhibitor）.Cell apoptosis was detected by flow cytometry with Annexin V/PI double-staining.Western blot analysis was used to examine the protein expression of GRP78,PI3K,p-PI3K,Akt,p-Akt,CHOP and Bax.The F test and t-test were used in statistical analyses.Results Flow cytometry showed that palmitate sodium induced cell apoptosis in steatotic hepatocytes;moreover,a significant increase in cell apoptosis was observed in the palmitate sodium-induced steatotic hepatocytes in the presence of LY294002.For the normal control group,the experimental group and the intervention group,the apoptosis ratios of L02 cells were 4.41±0.78% vs.6.01±1.49% vs.19.50±2.53% after 24 hours of treatment,and 12.56±2.78% vs.29.72±6.39% vs.44.60±4.17% after 48 hours of treatment in respectively （allP 〈 0.05）,and of HepG2 cells were 11.16±1.15% vs.17.50±6.83% vs.30.41±3.62% after 24 hours of treatment,and 22.37±1.24% vs.33.85±5.79% vs.48.56±4.21% after 48 hours of treatment （all P 〈 0.05）.Western blot analysis showed that expression of GRP78 was significantly upregulated in the palmitate sodium-induced steatosis hepatocytes,indicating activation of endoplasmic reticulum stress.In addition,the palmitate sodium treatment also activated the PI3K/Akt pathway,induced expression of CHOP and Bax of the UPR and non-UPR signaling pathways respectively.Moreover,pretreatment with LY294002 inhibited the palmitate sodium induced-phosphorylation of PI3K and Akt,and promo

关 键 词：肝细胞 细胞凋亡 内质网应激 PI3K/AKT CHOP BAX 

分 类 号：R575.5[医药卫生—消化系统]