Arginine and Leucine regulate p70 S6 kinase and 4E-BP1 in intestinal epithelial cells
Amino acids, especially branched-chain amino acids such as l-Leucine, have been revealed to regulate activation of p70 S6 kinase and phosphorylation of 4E-BP1 through mTOR signaling pathway. In this study, we showed that a cationic amino acid, l-Arginine, also activated this signaling pathway in a rapamycin-sensitive manner in rat intestinal epithelial cells, and this l-Arginine-induced amino acid signal transduction involved the cationic amino acid transport system. The manner of l-Arginine- and l-Leucine-induced activation of p70 S6 kinase depended on the stimulation time and the concentration of each amino acid, which suggested that the mechanism of this amino acid signal acceptance might be saturable. l-Arginine and l-Leucine induced activation of p70 S6 kinase and phosphorylation of 4E-BP1 in a rapamycin-sensitive manner, which suggested the involvement of mTOR signaling pathway in these effects. l-Arginine-induced activation of p70 S6 kinase was inhibited by NG-Methyl-L-Arginine (NMMA) and L-N5-(1-Iminoethyl) Ornithine (NIO), inhibitors of nitric oxide synthase (NOS) which also block cationic amino acid transporters, system y+. However, l-Leucine-induced activation of p70 S6 kinase was not affected with treatment of NOS inhibitors. In conclusion, l-Arginine regulates p70 S6 kinase activity and phosphorylation of 4E-BP1 through mTOR signaling pathway, which involves system y+, cationic amino acid transporters.
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Document Type: Research Article
Affiliations: Department of Gastroenterological Surgery, Transplant, and Surgical Oncology, Graduate School of Medicine and Dentistry, Okayama University, Okayama 700-8558, Japan
Publication date: April 1, 2004
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- The International Journal of Molecular Medicine is a monthly, peer-reviewed journal devoted to the publication of high quality studies related to the molecular mechanisms of human disease. The journal welcomes research on all aspects of molecular and clinical research, ranging from biochemistry to immunology, pathology, genetics, human genomics, microbiology, molecular pathogenesis, molecular cardiology, molecular surgery and molecular psychology.
The International Journal of Molecular Medicine aims to provide an insight for researchers within the community in regard to developing molecular tools and identifying molecular targets for the diagnosis and treatment of a diverse number of human diseases.
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