Clinical Pharmacology Institute, Anhui Medical University, Hefei, Anhui 230032, China.
Biochem Biophys Res Commun. 2012 Jan 13;417(2):738-43. doi: 10.1016/j.bbrc.2011.12.026. Epub 2011 Dec 16.
Endoplasmic reticulum (ER) stress occurs during early embryonic development. The aim of this study is to determine whether ER stress occurs during human embryonic stem cell differentiation induced by retinoic acid (RA). H9 human embryonic stem cells were subjected to RA treatment for up to 29days to induce differentiation. HEK293 cells were treated with RA as a control. The results demonstrate that several ER stress-responsive genes are differentially regulated in H9 and HEK293 cells in response to 5days of RA treatment. GRP78/Bip was upregulated in H9 cells but downregulated in HEK293 cells. eIF2α was downregulated in H9 cells but not in HEK293 cells. Phosphorylation of eIF2α was downregulated in H9 cells but upregulated in HEK293 cells. XBP-1 was downregulated immediately after RA treatment in H9 cells, but its downregulation was much slower in HEK293 cells. Additionally, two ER-resident E3 ubiquitin ligases, gp78 and Hrd1, were both upregulated in H9 cells following 5 days of exposure to RA. Moreover, the protein Bcl2 was undetectable in H9 cells and H9-derived cells but was expressed in HEK293 cells, and it expression in the two types of cells was unaltered by RA treatment. In H9 cells treated with RA for 29 days, GRP78/Bip, XBP-1 and Bcl2 were all upregulated. These results suggest that ER stress is involved in H9 cell differentiation induced by RA.
内质网（ER）应激发生在早期胚胎发育过程中。本研究旨在确定视黄酸（RA）诱导人胚胎干细胞分化过程中是否发生 ER 应激。将 H9 人胚胎干细胞用 RA 处理长达 29 天以诱导分化。将 HEK293 细胞用 RA 处理作为对照。结果表明，在 RA 处理 5 天后，H9 和 HEK293 细胞中几种 ER 应激反应基因的表达水平存在差异。GRP78/Bip 在 H9 细胞中上调，但在 HEK293 细胞中下调。eIF2α 在 H9 细胞中下调，但在 HEK293 细胞中没有下调。H9 细胞中 eIF2α 的磷酸化水平下调，但在 HEK293 细胞中上调。XBP-1 在 H9 细胞中 RA 处理后立即下调，但在 HEK293 细胞中下调速度较慢。此外，两种内质网驻留 E3 泛素连接酶 gp78 和 Hrd1 在 H9 细胞暴露于 RA 5 天后均上调。此外，Bcl2 蛋白在 H9 细胞及其衍生细胞中不可检测，但在 HEK293 细胞中表达，RA 处理对两种细胞中 Bcl2 的表达没有影响。在用 RA 处理 29 天的 H9 细胞中，GRP78/Bip、XBP-1 和 Bcl2 均上调。这些结果表明，ER 应激参与了 RA 诱导的 H9 细胞分化。
