title: L-Glutamine deprivation induces autophagy and alters the mTOR and MAPK signaling pathways in porcine intestinal epithelial cells.
abstract: L-Glutamine (Gln) is an essential amino acid for intestinal growth and integrity. However, the underlying molecular mechanisms are not fully known. In the present study, porcine intestinal epithelial cells (IPEC-1) were used to test the hypothesis that autophagy is induced by Gln deprivation and inhibited by Gln supplementation. After a 2-day period of growth in normal medium, IPEC-1 cells were transferred to a Gln-free custom-made DMEM. Cell numbers, the distribution of autophagosomes, the abundance of the protein for an autophagy marker LC3B, as well as abundances of the mTOR and MAPK proteins during an 8-h period were determined. Furthermore, the rescue effect of 5 mM Gln was evaluated. Our results showed that Gln deprivation reduced the cell number, while enhancing the accumulation of autophagosomes and the expression of LC3B-II in IPEC-1 cells within 8 h. The concentrations of Glu, Asp, Cit, Arg, Leu, Ile, Val, Ala, β-Ala, Orn, Phe, Met and Ser in the culture medium were altered by Gln deprivation. Further analysis revealed that Gln deficiency inactivated, but Gln supplementation activated, the mTOR and MAPK/ERK signaling pathways. Collectively, our findings support the notion that Gln deficiency induces autophagy and disturbs amino acid metabolism in intestinal epithelial cells, as well as attenuated their mTOR and MAPK/ERK signaling pathways to inhibit protein synthesis and cell proliferation.
authors.affiliation: State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China.
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Zhu
authors.affiliation: State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Lin
authors.affiliation: State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China.
authors.forename: Zhaolai
authors.initials: Z
authors.lastname: Dai
authors.affiliation: State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China.
authors.forename: Tianjiao
authors.initials: T
authors.lastname: Zhou
authors.affiliation: State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China.
authors.forename: Tiantian
authors.initials: T
authors.lastname: Li
authors.affiliation: State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China.
authors.forename: Taolin
authors.initials: T
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China.
authors.forename: Zhenlong
authors.initials: Z
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China.|Department of Animal Science, Texas A&M University, College Station, TX, 77843, USA.
authors.forename: Guoyao
authors.initials: G
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing, 100193, China. jkywjj@hotmail.com.
authors.forename: Junjun
authors.initials: J
authors.lastname: Wang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001343:Autophagy; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D005973:Glutamine / Q000172:deficiency* / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects / Q000473:pathology*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010539:Permeability / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects*; D013552:Swine; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism*
chemical_list: D005973:Glutamine; D058570:TOR Serine-Threonine Kinases; D020928:Mitogen-Activated Protein Kinases
keywords: Autophagy; IPEC-1; L-Glutamine; MAPKs; mTOR