Bile Acids Signal via TGR5 to Activate Intestinal Stem Cells and Epithelial Regeneration
Bile Acids Signal via TGR5 to Activate Intestinal Stem Cells and Epithelial Regeneration
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胆汁酸通过 TGR5 发出信号激活肠干细胞和上皮再生
DOI：
10.1053/j.gastro.2020.05.067
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发表时间：
2020-09-01
期刊：
影响因子：
29.4
通讯作者：
Schoonjans, Kristina
中科院分区：
文献类型：
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作者：
Sorrentino, Giovanni;Perino, Alessia;Schoonjans, Kristina
背景与目的：肠上皮的更新和模式化由肠干细胞（ISC）协调;饮食和代谢因素为控制ISC活性的小生境提供信号。胆汁酸（BA）是肠道中的代谢产物，通过激活G蛋白偶联胆汁酸受体1（GPBAR 1，也称为TGR 5）来发出营养物质可用性的信号。TGR 5在肠上皮中表达，但其活化如何影响ISCs和肠上皮的再生尚不清楚。我们研究了BAs和TGR 5在肠道更新中的作用，以及小鼠和肠道类器官中ISC功能的调节。方法：我们从野生型小鼠和Tgr 5（-/-）小鼠中获得肠类器官，将其与BA或TGR 5激动剂INT-777孵育，并通过形态学分析和集落形成试验监测ISC功能。我们在小鼠（Tgr 5ISC（-/-）小鼠）中特异性破坏Lgr 5阳性ISC中的Tgr 5，并通过流式细胞术、免疫荧光和类器官测定分析ISC数量、增殖和分化。Tgr 5ISC（-/-）小鼠给予胆囊收缩素，我们测量了BA释放到肠腔和细胞更新的影响。我们通过给予葡聚糖硫酸钠在Tgr 5ISC（-/-）小鼠中诱导结肠炎;基于体重、结肠长度和结肠活检的组织病理学分析来确定疾病严重程度。结果：BAs和TGR 5激动剂促进肠类器官的生长。给小鼠施用胆囊收缩素导致BA急性释放到肠腔中，并增加肠上皮细胞的增殖。BAs和Tgr 5在ISCs中的表达是稳态肠上皮更新和fatespecific以及结肠炎诱导后再生所必需的。Tgr 5ISC（-/-）小鼠比ISC中没有Tgr 5破坏的小鼠发生更严重的结肠炎。用INT-777孵育的ISC增加了yes相关蛋白1（YAP 1）及其上游调节因子SRC的活化。YAP 1和SRC的抑制剂阻止由TGR 5活化诱导的类器官生长。结论：BA通过激活ISCs中的TGR 5促进肠上皮的再生，导致SRC和雅普的激活及其靶基因的激活。肠腔中内源性BA的释放足以促进ISC更新并驱动响应于损伤的再生。
BACKGROUND & AIMS: Renewal and patterning of the intestinal epithelium is coordinated by intestinal stem cells (ISCs); dietary and metabolic factors provide signals to the niche that control ISC activity. Bile acids (BAs), metabolites in the gut, signal nutrient availability by activating the G protein-coupled bile acid receptor 1 (GPBAR1, also called TGR5). TGR5 is expressed in the intestinal epithelium, but it is not clear how its activation affects ISCs and regeneration of the intestinal epithelium. We studied the role of BAs and TGR5 in intestinal renewal, and regulation of ISC function in mice and intestinal organoids. METHODS: We derived intestinal organoids from wild-type mice and Tgr5(-/-) mice, incubated them with BAs or the TGR5 agonist INT-777, and monitored ISC function by morphologic analyses and colony-forming assays. We disrupted Tgr5 specifically in Lgr5-positive ISCs in mice (Tgr5ISC(-/-) mice) and analyzed ISC number, proliferation, and differentiation by flow cytometry, immunofluorescence, and organoid assays. Tgr5ISC(-/-) mice were given cholecystokinin; we measured the effects of BA release into the intestinal lumen and on cell renewal. We induced colitis in Tgr5ISC(-/-) mice by administration of dextran sulfate sodium; disease severity was determined based on body weight, colon length, and histopathology analysis of colon biopsies. RESULTS: BAs and TGR5 agonists promoted growth of intestinal organoids. Administration of cholecystokinin to mice resulted in acute release of BAs into the intestinal lumen and increased proliferation of the intestinal epithelium. BAs and Tgr5 expression in ISCs were required for homeostatic intestinal epithelial renewal and fatespecification, and for regeneration after colitis induction. Tgr5ISC(-/-) mice developed more severe colitis than mice without Tgr5 disruption in ISCs. ISCs incubated with INT-777 increased activation of yes-associated protein 1 (YAP1) and of its upstream regulator SRC. Inhibitors of YAP1 and SRC prevented organoid growth induced by TGR5 activation. CONCLUSIONS: BAs promote regeneration of the intestinal epithelium via activation of TGR5 in ISCs, resulting in activation of SRC and YAP and activation of their target genes. Release of endogenous BAs in the intestinal lumen is sufficient to promote ISC renewal and drives regeneration in response to injury.