title: Glutamine and KGF each regulate extracellular thiol/disulfide redox and enhance proliferation in Caco-2 cells.
abstract: Glutamine (Gln) and keratinocyte growth factor (KGF) each stimulate intestinal epithelial cell growth, but regulatory mechanisms are not well understood. We determined whether Gln and KGF alter intra- and extracellular thiol/disulfide redox pools in Caco-2 cells cultured in oxidizing or reducing cell medium and whether such redox variations are a determinant of proliferative responses to these agents. Cells were cultured over a physiological range of oxidizing to reducing extracellular thiol/disulfide redox (Eh) conditions, obtained by varying cysteine (Cys) and cystine (CySS) concentrations in cell medium. Cell proliferation was determined by 5-bromo-2-deoxyuridine (BrdU) incorporation. Gln (10 mmol/l) or KGF (10 microg/l) did not alter BrdU incorporation at reducing Eh (-131 to -150 mV), but significantly increased incorporation at more oxidizing Eh (Gln at 0 to -109 mV; KGF at -46 to -80 mV). Cellular glutathione/glutathione disulfide (GSH/GSSG) Eh was unaffected by Gln, KGF, or variations in extracellular Cys/CySS Eh. Control cells largely maintained extracellular Eh at initial values after 24 h (-36 to -136 mV). However, extracellular Eh shifted toward a narrow physiological range with Gln and KGF treatment (Gln -56 to -88 mV and KGF -76 to -92 mV, respectively; P < 0.05 vs. control). The results indicate that thiol/disulfide redox state in the extracellular milieu is an important determinant of Caco-2 cell proliferation induced by Gln and KGF, that this control is independent of intracellular GSH redox status, and that both Gln and KGF enhance the capability of Caco-2 cells to modulate extremes of extracellular redox.
authors.affiliation: Department of Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
authors.forename: Carolyn R
authors.initials: CR
authors.lastname: Jonas
authors.forename: Li H
authors.initials: LH
authors.lastname: Gu
authors.forename: Yvonne S
authors.initials: YS
authors.lastname: Nkabyo
authors.forename: Yanci O
authors.initials: YO
authors.lastname: Mannery
authors.forename: Nelly E
authors.initials: NE
authors.lastname: Avissar
authors.forename: Harry C
authors.initials: HC
authors.lastname: Sax
authors.forename: Dean P
authors.initials: DP
authors.lastname: Jones
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Ziegler
mesh_terms: D018938:Caco-2 Cells; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D003545:Cysteine / Q000378:metabolism; D003553:Cystine / Q000378:metabolism; D004220:Disulfides / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors / Q000494:pharmacology*; D005973:Glutamine / Q000494:pharmacology*; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D013438:Sulfhydryl Compounds / Q000378:metabolism*
chemical_list: D004220:Disulfides; C496453:FGF7 protein, human; D013438:Sulfhydryl Compounds; D005973:Glutamine; D051523:Fibroblast Growth Factor 7; D003553:Cystine; D005346:Fibroblast Growth Factors; D003545:Cysteine