内质网应激对心肌细胞FGF21及其受体表达的影响和机制研究*

摘要

目的：探讨内质网应激（ERS）对心肌细胞成纤维细胞生长因子21（FGF21）及其主要受体表达的影响和机制。方法在大鼠H9c2心肌细胞中加入不同浓度的衣霉素（TM）（1、5、10、20和50μmol/L）复制ERS模型，利用活细胞计数法试剂盒检测细胞存活率。Western blot检测凋亡相关蛋白（C- caspase3、GRP78、Bax、Bcl-2）和PERK- eIF2α- ATF4信号通路相关蛋白（p- PERK、p- eIF2α、ATF4），CHOP蛋白，FGF21及其主要受体（p- FGFR1和β- Klotho）的表达。结果与对照组比较，TM处理组诱导H9c2细胞发生ERS，提高促凋亡蛋白C- caspase3、GRP78、Bax的表达，减少抗凋亡蛋白Bcl-2的表达，并以浓度依赖形式降低细胞的存活率。此外，当TM浓度≤10μmol/L时，TM处理组可以部分激活PERK- eIF2α- ATF4信号通路，诱导FGF21、p- FGFR1、β-Klotho的表达；当TM浓度>10μmol/L时，TM处理组完全激活PERK- eIF2α- ATF4信号通路，诱导CHOP的表达，而FGF21、p- FGFR1及β- Klotho表达却随TM浓度的增加而逐渐降低。结论 FGF21及其主要受体的表达与ERS程度有关，轻微的ERS（TM浓度≤10μmol/L）诱导心肌细胞FGF21及其受体的表达，而严重的ERS（TM浓度>10μmol/L）则相对降低FGF21及其受体的表达，其机制可能与PERK- eIF2α- ATF4信号通路在ERS中的调控有关。%Objective To investigate the effect of endoplasmic reticulum stress (ERS) on the expressions of fibroblast growth factor 21 (FGF21) and its main receptors in cardiomyocytes and its mechanism. Methods ERS model was established by treating rat H9c2 cardiomyocytes with various concentrations of Tunicamycin (TM) (1, 5, 10, 20 and 50μmol/L). The cell survival rate was measured by CCK-8 assay. The expression of apoptosis-related proteins (c-caspase3, GRP78, Bax and Bcl-2), the key proteins of PERK-eIF2α-ATF4 sig-naling pathway (p-PERK, p-eIF2α and ATF4), CHOP as well as FGF21 and its main receptors (p-FGFR1 and β-Klotho) were measured by Western blot. Results Compared with the control group, TM treatment in-duced ERS in H9c2 cells, up-regulated the expression of pro-apoptosis proteins including c-caspase3, GRP78 and Bax, and reduced the level of anti-apoptosis protein Bcl-2; meanwhile it reduced cell viability rate in a dose-dependent manner. In addition, in the TM treated group the PERK-eIF2α-ATF4 signaling pathway was partly activated, which significantly induced expressions of FGF21, p-FGFR1 and β-Klotho when the concen-tration of TM was ≤10μmol/L. However, when the concentration of TM was>10 μmol/L, the expression of CHOP was significantly induced through fully-activated PERK-eIF2α-ATF4 signaling pathway, but the expres-sions of FGF21, p-FGFR1 and β-Klotho gradually decreased with the increase of ERS level. Conclusions The expressions of FGF21 and its main receptors correlate with the degree of ERS. Mild ERS (TM ≤ 10μmol/L) induces the expression of FGF21 and its main receptors in cardiomyocytes, while excessive ERS (TM >10 μmol/L) relatively reduces their expressions. The mechanism might be partly related to the regulation of PERK-eIF2α-ATF4 pathway in ERS.