title: Glutamine activates peroxisome proliferator-activated receptor-γ in intestinal epithelial cells via 15-S-HETE and 13-OXO-ODE: a novel mechanism.
abstract: Glutamine possesses gut-protective effects both clinically and in the laboratory. We have shown in a rodent model of mesenteric ischemia-reperfusion that enteral glutamine increased peroxisome proliferator-activated receptor-γ (PPAR-γ) and was associated with a reduction in mucosal injury and inflammation. The mechanism by which glutamine activates PPAR-γ is unknown, and we hypothesized that it was via a ligand-dependent mechanism. Intestinal epithelial cells, IEC-6, were co-transfected with PPAR-γ response element-luciferase promoter/reporter construct. Cells were pretreated with increasing concentrations of glutamine ± GW9662 (a specific antagonist of PPAR-γ) and analyzed for PPAR-γ response element luciferase activity as an indicator of PPAR-γ activation. PPAR-γ nuclear activity was assessed by electrophoretic mobility shift assay. Cell lysates were subjected to tandem mass spectroscopy for measurement of prostaglandin and lipoxygenase metabolites. A time- and concentration-dependent increase in PPAR-γ transcriptional activity, but not mRNA or protein, was demonstrated. Activity was abrogated by the PPAR-γ inhibitor, GW9662, and changes in activity correlated with PPAR-γ nuclear binding. Glutamine, via degradation to glutamate, activated the metabolic by-products of the lipoxygenase and linoleic acid pathways, 15-S-hydroxyeicosatetraenoic acid and dehydrogenated 13-hydroxyoctaolecadienoic acid, known endogenous PPAR-γ ligands in the small bowel. This novel mechanism may explain the gut-protective effects of enteral glutamine.
authors: Department of Surgery, University of Texas Health Science Center at Houston, Houston, TX 77030, USA. Rosemary.A.Kozar@uth.tmc.edu
authors: Kechen
authors: K
authors: Ban
authors: Julie M
authors: JM
authors: Sprunt
authors: Stephanie
authors: S
authors: Martin
authors: Peiying
authors: P
authors: Yang
authors: Rosemary A
authors: RA
authors: Kozar
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005973:Glutamine / Q000378:metabolism*; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000166:cytology*; D008042:Linolenic Acids / Q000378:metabolism*; D047495:PPAR gamma / Q000819:agonists / Q000378:metabolism*; D051381:Rats
chemical_list: D006893:Hydroxyeicosatetraenoic Acids; D008042:Linolenic Acids; D047495:PPAR gamma; D005973:Glutamine; C064441:13-oxo-9,11-octadecadienoic acid; C025984:15-hydroxy-5,8,11,13-eicosatetraenoic acid