Glutamine and interleukin-1beta interact at the level of Sp1 and nuclear factor-kappaB to regulate argininosuccinate synthetase gene expression.
We previously demonstrated that the expression of the argininosuccinate synthetase (ASS) gene, a key step in nitric oxide production, is stimulated either by interleukin-1beta[Brasse-Lagnel et al. (2005) Biochimie 87, 403-9] or by glutamine in Caco-2 cells [Brasse-Lagnel et al. (2003) J. Biol. Chem. 278, 52504-10], through the activation of transcription factors nuclear factor-kappaB and Sp1, respectively. In these cells, the fact that glutamine stimulated the expression of a gene induced by pro-inflammatory factors appeared paradoxical as the amino acid is known to exert anti-inflammatory properties in intestinal cells. We therefore investigated the effect of simultaneous addition of both glutamine and interleukin-1beta on ASS gene expression in Caco-2 cells. In the presence of both compounds for 4 h, the increases in ASS activity, protein amount and mRNA level were almost totally inhibited, implying a reciprocal inhibition between the amino acid and the cytokine. The inhibition was exerted at the level of the transcription factors Sp1 and nuclear-kappaB: (a) interleukin-1beta inhibited the glutamine-stimulated DNA-binding of Sp1, which might be related to a decrease of its glutamine-induced O-glycosylation, and (b) glutamine induced per se a decrease in the amount of nuclear p65 protein without affecting the stimulating effect of interleukin-1beta on nuclear factor-kappaB, which might be related to the metabolism of glutamine into glutamate. The present results constitute the first demonstration of a reciprocal inhibition between the effects of an amino acid and a cytokine on gene expression, and provide a molecular basis for the protective role of glutamine against inflammation in the intestine.
Brasse-Lagnel
Carole
C
Groupe Appareil Digestif, Environnement et Nutrition, Institut Fédératif de Recherches Multidisciplinaires sur Peptides, Université de Rouen, France.
Lavoinne
Alain
A
Loeber
David
D
Fairand
Alain
A
Bôle-Feysot
Christine
C
Deniel
Nicolas
N
Husson
Annie
A
D001124:Argininosuccinate Synthase / Q000235:genetics* / Q000378:metabolism; D015153:Blotting, Western; D018938:Caco-2 Cells / Q000187:drug effects / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D004357:Drug Synergism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D005973:Glutamine / Q000494:pharmacology*; D006801:Humans; D047468:Immunoprecipitation; D053583:Interleukin-1beta / Q000494:pharmacology*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016329:Sp1 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D053583:Interleukin-1beta; D016328:NF-kappa B; D012333:RNA, Messenger; D016329:Sp1 Transcription Factor; D005973:Glutamine; D009569:Nitric Oxide; D001124:Argininosuccinate Synthase