过表达NR2E1对棕榈酸诱导的NIT1细胞凋亡及内质网应激的影响

Effect of NR2E1 overexpression on apoptosis and endoplasmic reticulum stress induced by palmitate in pancreatic beta cells

目的研究孤儿核受体NR2E1对棕榈酸(PA)诱导的胰岛β细胞凋亡及内质网应激的影响。方法建立过表达NR2E1小鼠胰岛细胞系NIT1细胞株,予500μmol/L PA处理24 h,采用流式细胞仪检测细胞凋亡,RT-PCR检测C/EBP同源蛋白(CHOP)、葡萄糖调节蛋白78(GRP78)mRNA表达变化,Western blot检测磷酸化真核翻译起始因子2α(p-eIF2α)的水平。结果过表达NR2E1能减少PA诱导的NIT1细胞凋亡率[(27.5±0.4)%vs(11.9±0.4)%]和CHOP mRNA表达[(10.54±1.98)vs(3.03±0.49)],增加GRP78 mRNA表达[(3.28±0.20)vs(5.28±0.49)]和eIF2α磷酸化水平[(1.26±0.13)vs(1.67±0.06)](P<0.05)。结论过表达NR2E1能减轻PA诱导的胰岛β细胞凋亡,其机制可能与调节内质网应激有关。

Objective To investigate the effect of orphan nuclear receptors NR2E1 overexpression on apoptosis and endoplasmic reticulum stress induced by palmitate （PA）in mouse islet beta cell line NIT1. Methods NR2E1 overexpressed cell line NIT1 in mouse islet beta cell was established. The cell lines were exposed to 500 μmol/L palmitate for 24 h. Cells apoptosis was analyzed by flow cytometry. RT- PCR was performed to detect mRNA levels of NR2E1 and ER stress-associated markers such as CHOP and GRP78. Western blot analysis was used to determine the protein levels of NR2E1, p-eIF2α and eIF2α. Results Upregulating NR2E1 reduced cell apoptosis in palmitate-treated NIT1 cells[（27.5±0.4）% vs （11.9 ± 0.4）M] （P〈0.01）. NR2E1 overexpression decreased the level of CHOP mRNA [ （10.54±1.98） vs （3. 03±0. 49）],increased the level of GRP78 mRNA [（3.28±0. 20） vs （5.28±0. 49）],and increased the level of p-eIF2a protein [（1.67±0.06） vs （1.26±0.13）] in 500μmol/L palmitate-treated NIT1 cells （P〈0.05）. Conclusion Up-regulation of NR2E1 expression may inhibit the apoptosis of palmitatetreated islet beta cells. The mechanism may be related to attenuating ER stress.