期刊
AMINO ACIDS
卷 47, 期 1, 页码 65-78出版社
SPRINGER WIEN
DOI: 10.1007/s00726-014-1842-8
关键词
L-Glutamine; IPEC-1; mTOR; AMPK
资金
- National Basic Research Program of China [2012CB126305]
- National Natural Science Foundation of China [31372319, 31402084]
- Hubei Provincial Research and Development Program [2010BB023]
- Natural Science Foundation of Hubei Province [2013CFA097, 2013CFB325, 2012FFB04805, 2011CDA131]
- Hubei Hundred Talent program, Agriculture and Food Research Initiative Competitive Grant of the USDA National Institute of Food and Agriculture [2014-67015-21770]
- Texas AgriLife Research [H-82000]
Neonates (including human infants) require l-glutamine (Gln) for optimal intestinal health. This study tested the hypothesis that Gln enhances enterocyte growth via both mammalian target of rapamycin (mTOR) and AMP-activated kinase (AMPK) signaling pathways. Intestinal porcine epithelial cells (IPEC-1) were cultured for 3 days in Gln-free Dulbecco's modified Eagle medium containing 0 or 2 mM Gln. To determine the role of mTOR and AMPK on cell growth, additional experiments were conducted where medium contained 2 mM Gln and 10 nM rapamycin (Rap, an inhibitor of mTOR) or 1 mu M compound C (an inhibitor of AMPK). IPEC-1 cell growth increased with increasing concentrations of Gln from 0 to 2 mM. Compared with 0 mM Gln, 2 mM Gln increased (P < 0.05) the amounts of phosphorylated 4E-binding protein 1 (4E-BP1) and ribosomal protein S6 kinase (p70S6 kinase) proteins but did not affect abundances of total or phosphorylated AMPK protein. Gln also increased mRNA levels for Bcl-2, mTOR, p70S6 kinase, 4E-BP1, COX7C, ASCT2, ODC, SGLT-1, CFTR, Na+/K+-ATPase, HSP70, and ZO-1. Similarly, cells cultured with Rap and Gln exhibited higher (P < 0.05) abundances of phosphorylated 4E-BP1 and p70S6 kinase proteins than the Rap-only group, whereas abundances of phosphorylated mTOR and 4E-BP1 proteins were increased when AMPK was inhibited by compound C. Conversely, the amount of phosphorylated AMPK increased when mTOR was inhibited by Rap, suggesting a negative cross-talk between mTOR and AMPK. Collectively, these results indicate that Gln stimulates enterocyte growth by activating the mTOR signaling pathway independently of AMPK.
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