Mao Xiangbing, Hu Haiyan, Tang Jun, Chen Daiwen, Yu Bing
Animal Nutrition Institute, Sichuan Agricultural University, Ya'an 625014, China.
Key Laboratory of Animal Disease-Resistance Nutrition, Ministry of Education, Ya'an 625014, China.
Anim Nutr. 2016 Sep;2(3):218-224. doi: 10.1016/j.aninu.2016.05.004. Epub 2016 Jun 2.
Mucin 2 and occludin play a crucial role in preserving the intestinal mucosal integrity. However, the role for leucine mediating intestinal mucin 2 and occludin expression has little been investigated. The current study was conducted to test the hypothesis that leucine treatment could increase mucin 2 and occludin levels in LS174T cells. The LS174T cells were incubated in the Dulbecco's Modified Eagle Medium (DMEM) supplementing 0, 0.5 and 5 mmol/L L-leucine for the various durations. Two hours after the leucine treatment, the inhibitor of mammalian target of rapamycin (mTOR) and protein kinase B (Akt) phosphorylation in LS174T cells were significantly increased ( < 0.05), and the mucin 2 and occludin levels were also significantly enhanced ( < 0.05). However, the pretreatment of 10 nmol/L rapamycin, which was an mTOR inhibitor, or 1 μmol/L wortmanin, which was an inhibitor of phosphatidylinositol 3-kinase (PI3K), completely inhibited leucine-induced mTOR or Akt phosphorylation ( < 0.05), and significantly reduced leucine-stimulated mucin 2 and occludin levels ( < 0.05). These results suggest that leucine treatment promotes the mucin 2 and occludin levels in LS174T cells partially through the PI3K-Akt-mTOR signaling pathway.
黏蛋白2和闭合蛋白在维持肠道黏膜完整性方面发挥着关键作用。然而，亮氨酸介导肠道黏蛋白2和闭合蛋白表达的作用鲜有研究。本研究旨在验证亮氨酸处理可增加LS174T细胞中黏蛋白2和闭合蛋白水平这一假说。将LS174T细胞在补充了0、0.5和5 mmol/L L-亮氨酸的杜尔贝科改良伊格尔培养基（DMEM）中孵育不同时长。亮氨酸处理两小时后，LS174T细胞中雷帕霉素靶蛋白（mTOR）和蛋白激酶B（Akt）磷酸化的抑制剂显著增加（<0.05），黏蛋白2和闭合蛋白水平也显著提高（<0.05）。然而，10 nmol/L雷帕霉素（一种mTOR抑制剂）或1 μmol/L渥曼青霉素（一种磷脂酰肌醇3激酶（PI3K）抑制剂）的预处理完全抑制了亮氨酸诱导的mTOR或Akt磷酸化（<0.05），并显著降低了亮氨酸刺激的黏蛋白2和闭合蛋白水平（<0.05）。这些结果表明，亮氨酸处理部分通过PI3K-Akt-mTOR信号通路促进LS174T细胞中黏蛋白2和闭合蛋白水平。
