Astragalus Polysaccharides Protects Thapsigargin-induced Endoplasmic Reticulum Stress in HT29 Cells

Lie Zheng; Ya-Li Zhang; Xuan Chen; De-Liang Chen; Yan-Cheng Dai; Zhi-Peng Tang

doi:10.1515/biol-2019-0055

Astragalus Polysaccharides Protects Thapsigargin-induced Endoplasmic Reticulum Stress in HT29 Cells

Open Life Sci. 2019 Dec 31:14:494-501. doi: 10.1515/biol-2019-0055. eCollection 2019 Jan.

Authors

Lie Zheng^{1

2}, Ya-Li Zhang¹, Xuan Chen³, De-Liang Chen^{1

4}, Yan-Cheng Dai^{1

5}, Zhi-Peng Tang¹

Affiliations

¹ Institute of Digestive Diseases, LongHua Hospital, Shanghai University of Traditional Chinese Medicine, 725 Wanping Road, Shanghai 200032, China.
² Department of Gastroenterology, Shaanxi Hospital of Traditional Chinese Medicine, Xi'an 710003, Shaanxi, Xi'an, China.
³ Shanghai University of Traditional Chinese Medicine, Shanghai 201203, China.
⁴ Department of Tuina, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing 210029, China.
⁵ Department of Gastroenterology, Shanghai Traditional Chinese Medicine-Integrated Hospital, Shanghai University of Traditional Chinese Medicine, 230 Baoding Road, Shanghai 200082, China.

Abstract

Aim: This study investigates the effect of astragalus polysaccharides (APS) in protecting against thapsigargin-induced endoplasmic reticulum (ER) stress in HT29 cells by suppressing the PERK-eIF2a signaling pathway.

Methods: HT29 cells were induced by thapsigargin for 12 hours, then treated with APS for 24 hours, and the gene expressions of GRP78, CHOP and eIF2a were quantified by reverse transcription quantitative polymerase chain reaction (RT-qPCR). The expression of GRP78, CHOP, PERK, p-PERK, eIF2a, and p-eIF2a were detected by Western blot.

Results: The ER stress caused by thapsigargin strongly up-regulated the expression of GRP78 and CHOP in HT29 cells, which activated the PERK-eIF2a pathway. There was an increase in PERK phosphorylation, and induction of eIF2a in HT29 cells. Thapsigargin caused significant ER expansion in HT29 cells due to the 12-hour ER stress. Importantly, Astragalus polysaccharide significantly inhibited the phosphorylation of PERK and eIF2a, which reduced the mRNA levels of GRP78, CHOP, PERK and eIF2a, and inhibited the ER expansion in HT29 cells after 24 hours of treatment.

Conclusion: The results indicate that APS reduces the expression of GRP78 and CHOP in HT29 cells, at least in part, by preventing the activation of the PERK-eIF2a signaling pathway.

Keywords: Astragalus polysaccharides; ER stress; HT29 cells; PERK-eIF2a signaling; Thapsigargin.