TGR5 agonist inhibits intestinal epithelial cell apoptosis via cAMP/PKA/c-FLIP/JNK signaling pathway and ameliorates dextran sulfate sodium-induced ulcerative colitis  

作　　者：Wen-ji Yang Fang-hui Han Yi-pei Gu Hui Qu Jia Liu Jian-hua Shen Ying Leng 

机构地区：[1]State Key Laboratory of Drug Research,Shanghai Institute of Materia Medica,Chinese Academy of Sciences,Shanghai,201203,China [2]University of Chinese Academy of Sciences,Beijing,100049,China [3]Shanghai Institute of Materia Medica,Chinese Academy of Sciences,Shanghai,201203,China

出　　处：《Acta Pharmacologica Sinica》2023年第8期1649-1664,共16页中国药理学报（英文版）

基　　金：supported by National Natural Science Foundation of China (No.81872922 and 82073683).

摘　　要：Excessive apoptosis of intestinal epithelial cell(IEC)is a crucial cause of disrupted epithelium homeostasis,leading to the pathogenesis of ulcerative colitis(UC).The regulation of Takeda G protein-coupled receptor-5(TGR5)in IEC apoptosis and the underlying molecular mechanisms remained unclear,and the direct evidence from selective TGR5 agonists for the treatment of UC is also lacking.Here,we synthesized a potent and selective TGR5 agonist OM8 with high distribution in intestinal tract and investigated its effect on IEC apoptosis and UC treatment.We showed that OM8 potently activated hTGR5 and mTGR5 with EC50 values of 202±55 nM and 74±17 nM,respectively.After oral administration,a large amount of OM8 was maintained in intestinal tract with very low absorption into the blood.In DSS-induced colitis mice,oral administration of OM8 alleviated colitis symptoms,pathological changes and impaired tight junction proteins expression.In addition to enhancing intestinal stem cell(ISC)proliferation and differentiation,OM8 administration significantly reduced the rate of apoptotic cells in colonic epithelium in colitis mice.The direct inhibition by OM8 on IEC apoptosis was further demonstrated in HT-29 and Caco-2 cells in vitro.In HT-29 cells,we demonstrated that silencing TGR5,inhibition of adenylate cyclase or protein kinase A(PKA)all blocked the suppression of JNK phosphorylation induced by OM8,thus abolished its antagonizing effect against TNF-αinduced apoptosis,suggesting that the inhibition by OM8 on IEC apoptosis was mediated via activation of TGR5 and cAMP/PKA signaling pathway.Further studies showed that OM8 upregulated cellular FLICE-inhibitory protein(c-FLIP)expression in a TGR5-dependent manner in HT-29 cells.Knockdown of c-FLIP blocked the inhibition by OM8 on TNF-αinduced JNK phosphorylation and apoptosis,suggesting that c-FLIP was indispensable for the suppression of OM8 on IEC apoptosis induced by OM8.In conclusion,our study demonstrated a new mechanism of TGR5 agonist on inhibiting IEC apoptosis via cAMP

关 键 词：TGR5 agonist ulcerative colitis intestinal epithelial cell APOPTOSIS cAMP/PKA signaling pathway C-FLIP 

分 类 号：R363[医药卫生—病理学]