Extracellular glutamate-induced mTORC1 activation via the IR/IRS/PI3K/Akt pathway enhances the expansion of porcine intestinal stem cells
Extracellular glutamate-induced mTORC1 activation via the IR/IRS/PI3K/Akt pathway enhances the expansion of porcine intestinal stem cells
复制标题
细胞外谷氨酸通过 IR/IRS/PI3K/Akt 途径诱导 mTORC1 激活增强猪肠干细胞的扩增
DOI：
10.1021/acs.jafc.9b03626
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发表时间：
2019
影响因子：
6.1
通讯作者：
Xiu-Qi Wang
中科院分区：
文献类型：
--
作者：
Min Zhu;Ying-Chao Qin;Chun-Qi Gao;Hui-Chao Yan;Xiang-Guang Li;Xiu-Qi Wang
谷氨酸（Glu）是肠上皮稳态的重要营养调节剂。此外，隐窝基的肠干细胞（ISCs）在维持肠上皮的更新和稳态中起着重要作用，Glu和ISCs之间的通讯方面仍不清楚。在这里，我们发现Glu和哺乳动物雷帕霉素靶复合物1 （mTORC1）是ISC扩增的重要调节因子。结果表明，细胞外Glu促进了ISC的扩增，表现为肠道类器官形成效率和出芽效率的提高以及细胞增殖标志物Ki67和分化标志物Keratin 20 （KRT20）的表达。此外，胰岛素受体（IR）介导的胰岛素受体底物（IRS）磷酸化和下游信号通路磷酸肌肽3激酶(PI3K)/蛋白激酶B （Akt）通路参与了ISCs的这种反应。正如预期的那样，在肠猪肠细胞细胞系（IPEC-J2）中观察到Glu诱导的mTORC1信号激活，并且Glu激活了PI3K/Akt/mTORC1通路。因此，PI3K抑制部分抑制了glu诱导的mTORC1激活。此外，Glu增加了IR和IRS的磷酸化水平，抑制IR下调了IRS/PI3K/Akt通路。总之，我们的研究结果首次表明，细胞外Glu通过IR/IRS/PI3K/Akt通路激活mTORC1，刺激ISC扩增，为调节肠上皮的生长和健康提供了新的视角。
Glutamate (Glu) is a critical nutritional regulator of intestinal epithelial homeostasis. In addition, intestinal stem cells (ISCs) at crypt bases are known to play important roles in maintaining the renewal and homeostasis of the intestinal epithelium, and the aspects of communication between Glu and ISCs are still unknown. Here, we identify Glu and mammalian target of rapamycin complex 1 (mTORC1) as essential regulators of ISC expansion. The results showed that extracellular Glu promoted ISC expansion, indicated by increased intestinal organoid forming efficiency and budding efficiency as well as cell proliferation marker Ki67 immunofluorescence and differentiation marker Keratin 20 (KRT20) expression. Moreover, the insulin receptor (IR) mediating phosphorylation of the insulin receptor substrate (IRS) and downstream signaling phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathway was involved in this response in ISCs. As expected, Glu-induced mTORC1 signaling activation was observed in the intestinal porcine enterocyte cell line (IPEC-J2), and Glu activated the PI3K/Akt/mTORC1 pathway. Accordingly, PI3K inhibition partially suppressed Glu-induced mTORC1 activation. In addition, Glu increased the phosphorylation levels of IR and IRS, and inhibiting IR downregulated the IRS/PI3K/Akt pathway. Collectively, our findings first indicate that extracellular Glu activates mTORC1 via the IR/IRS/PI3K/Akt pathway and stimulates ISC expansion, providing a new perspective for regulating the growth and health of the intestinal epithelium.