FABP4沉默通过调节PERK/eIF2α/ATF4/CHOP信号通路对妊娠糖尿病大鼠内质网应激和胰岛素抵抗的影响

Impacts of FABP4 silencing on endoplasmic reticulum stress and insulin resistance in gestational diabetes mellitus rats by regulating PERK/eIF2α/ATF4/CHOP signaling pathway

目的:探讨脂肪酸结合蛋白4(FABP4)沉默通过调节蛋白激酶R样内质网激酶(PERK)/真核细胞启动因子2α(eIF2α)/转录因子4(ATF4)/C/EBP同源蛋白(CHOP)信号通路对妊娠糖尿病(GDM)大鼠内质网应激(ERS)和胰岛素抵抗(IR)的影响。方法:腹腔注射链脲佐菌素(STZ)建立GDM大鼠模型。通过尾静脉注射FABP4 siRNA质粒(si-FABP4)、阴性对照质粒(NC)和PERK激活剂(CCT020312),将大鼠随机分为Normal组、GDM组、GDM+NC组、GDM+si-FABP4组、GDM+si-FABP4+CCT020312组。检测胰腺组织中FABP4含量、血脂水平、炎症标志物水平和氧化应激标志物水平,检测胰腺组织中PERK/eIF2α/ATF4/CHOP信号通路相关蛋白表达。HTR-8/SVneo细胞分为5组:对照(Control)组、高糖(HG)组、HG+NC组、HG+si-FABP4组、HG+si-FABP4+CCT020312组,24 h后检测细胞中FABP4及PERK/eIF2α/ATF4/CHOP信号通路相关蛋白表达。结果:与Normal组相比,GDM组大鼠血清和胰腺组织中FABP4水平显著上调(P<0.05)。FABP4沉默显著降低了FBG和IR,并伴有血脂、CRP、TNF-α、IL-6及MDA水平降低和SOD、CAT水平升高(P<0.05)。此外,FABP4沉默减轻了胰腺和胎盘组织损伤。而CCT020312上调PERK、eIF2α磷酸化水平和ATF4、CHOP蛋白表达后,FABP4沉默对GDM大鼠IR、炎症、氧化应激以及胰腺和胎盘损伤的抑制作用均被逆转(P<0.05)。FABP4在HG诱导的HTR-8/SVneo细胞中上调表达,沉默FABP4可抑制PERK/eIF2α/ATF4/CHOP通路蛋白表达,CCT020312则逆转这种变化(P<0.05)。结论:FABP4沉默通过抑制炎症和氧化应激,改善GDM大鼠的IR和ERS,其机制与抑制PERK/eIF2α/ATF4/CHOP信号通路有关。

Objective:To investigate the impacts of fatty acid binding protein 4(FABP4)silencing on endoplasmic reticulum stress(ERS)and insulin resistance(IR)in gestational diabetes mellitus(GDM)rats by regulating protein kinase R-like endoplasmic reticulum kinase(PERK)/eukaryotic initiation factor 2α(eIF2α)/transcription factor 4(ATF4)/C/EBP homologous protein(CHOP)signaling pathway.Methods:GDM rat model was established by intraperitoneal injection of streptozotocin(STZ).Rats were injected with FABP4 siRNA plasmid(si-FABP4),negative control plasmid(NC)and PERK activator(CCT020312)via tail vein,and were randomly grouped into Normal group,GDM group,GDM+NC group,GDM+si-FABP4 group and GDM+si-FABP4+CCT020312 group.The levels of FABP4,blood lipids,inflammatory markers and oxidative stress markers in pancreatic tissue were detected,the expressions of PERK/eIF2α/ATF4/CHOP signaling pathway-related proteins in pancreatic tissue were detected.HTR-8/SVneo cells were divided into 5 groups:Control group,high glucose(HG)group,HG+NC group,HG+si-FABP4 group,HG+si-FABP4+CCT020312 group.After 24 h,the expressions of FABP4 and PERK/eIF2α/ATF4/CHOP signaling pathway related proteins were detected.Results:Compared with Normal group,the level of FABP4 in the serum and pancreatic tissue of the GDM group were obviously up-regulated(P<0.05).FABP4 silencing obviously reduced FBG and IR,decreased the levels of blood lipids,CRP,TNF-α,IL-6 and MDA,and increased the levels of SOD and CAT(P<0.05).Furthermore,FABP4 silencing attenuated pancreatic and placental tissue damages.After CCT020312 up-regulated the phosphorylation levels of PERK and eIF2αand the protein expressions of ATF4 and CHOP,the inhibitory effects of FABP4 silencing on IR,inflammation,oxidative stress,and pancreatic and placental damages in GDM rats were reversed(P<0.05).FABP4 was up-regulated in HTR-8/SVneo cells induced by HG,and silencing FABP4 inhibited the protein expression of the PERK/eIF2α/ATF4/CHOP pathway,while CCT020312 reversed this change(P<0.05).Conclusion:FABP4 silencing improves IR and ERS in GDM rats by inhibiting inflammation and oxidative stress,and the mechanism is related to the inhibition of PERK/eIF2α/ATF4/CHOP signaling pathway.