title: L-Glutamate deficiency can trigger proliferation inhibition via down regulation of the mTOR/S6K1 pathway in pig intestinal epithelial cells.
abstract: The objective of this study was to investigate the effects of L-glutamate (Glu) deficiency or L-trans pyrrolidine-2,4-dicarboxylic acid (PDC) supplementation on the proliferation of pig intestinal epithelial cells (IPEC-1). First, IPEC-1 cells were cultured in normal growing medium supplemented with 0 (Control), 50, 100, or 200 µmol/L PDC to determine an appropriate concentration of PDC supplementation. Second, IPEC-1 cells were cultured in Glu-deficient medium supplemented with 0 µmol/L Glu (Glu deficiency), 50 µmol/L Glu (Control), or 50 µmol/L Glu plus 100 µmol/L PDC (PDC supplementation). Cell proliferation ( = 24), cell cycle distribution ( = 6), cell apoptosis ( = 6), and expression levels of proteins of interest ( = 4) were determined by MTT assay, flow cytometry, or western blot. The results showed that cell proliferation was inhibited ( < 0.05) by 50, 100, and 200 µmol/L PDC supplementation at 24 and 48 h after treatment. Variance analysis was performed using the GLM procedure, and the results demonstrated that Glu deficiency or PDC supplementation led to the inhibition ( < 0.05) of cell proliferation, a greater ( < 0.05) percentage of cells in the G1 phase, and a lower ( < 0.05) percentage of cells in the S phase. Moreover, Glu deficiency or PDC supplementation reduced ( < 0.05) the expression levels of excitatory AA transporter 3 (EAAT3), phosphor-mammalian target of rapamycin (p-mTOR; Ser2448), p-ribosomal protein S6 kinase 1 (S6K1; Thr389), and p-S6 (Ser235/236). This study demonstrates that Glu deficiency or PDC supplementation inhibits proliferation of IPEC-1 cells via downregulation of the mTOR/S6K1 pathway and EAAT3 expression indicating that Glu deficiency may lead to the disturbances of intestinal epithelial renewal in pigs, particularly in neonates.
authors.forename: X-G
authors.initials: XG
authors.lastname: Li
authors.forename: W-G
authors.initials: WG
authors.lastname: Sui
authors.forename: C-Q
authors.initials: CQ
authors.lastname: Gao
authors.forename: H-C
authors.initials: HC
authors.lastname: Yan
authors.forename: Y-L
authors.initials: YL
authors.lastname: Yin
authors.forename: H-C
authors.initials: HC
authors.lastname: Li
authors.forename: X-Q
authors.initials: XQ
authors.lastname: Wang
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle; D049109:Cell Proliferation / Q000187:drug effects / Q000502:physiology*; D003998:Dicarboxylic Acids / Q000008:administration & dosage / Q000494:pharmacology; D015536:Down-Regulation; D004847:Epithelial Cells / Q000187:drug effects* / Q000502:physiology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D018698:Glutamic Acid / Q000172:deficiency* / Q000494:pharmacology; D007422:Intestines / Q000187:drug effects; D011759:Pyrrolidines / Q000008:administration & dosage / Q000494:pharmacology; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013552:Swine; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D003998:Dicarboxylic Acids; D011759:Pyrrolidines; D018698:Glutamic Acid; C083486:pyrrolidine-2,4-dicarboxylic acid; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases