Down-regulation of alpha class glutathione S-transferase by interleukin-1beta in human intestinal epithelial cells (Caco-2) in culture.
The influence of pro-inflammatory cytokines on alpha class glutathione S-transferase A1 and A2 (GSTA1/A2) expression was examined in human colonic epithelial cells (Caco-2) in culture. Dose-dependent reductions in GSTA1/A2 mRNA, protein, and activity levels occurred in Caco-2 cells cultured in conditioned medium (CM) from lipopolysaccharide-stimulated murine monocyte-macrophage cells (RAW 264.7). Neutralizing anti-interleukin-1beta (IL-1beta) antibodies attenuated this repression of GSTA1/A2 expression by CM. Moreover, recombinant human IL-1beta reduced GSTalpha expression at the mRNA, protein, and activity levels in a dose-related fashion. Reduction of GSTA1/A2 mRNA levels by IL-1beta was attenuated by pretreatment with IL-1 receptor antagonist. GSTA1/A2 mRNA half-lives were similar in control and IL-1beta-treated cells, indicating that IL-1beta has no effect on mRNA stability. In reporter gene studies, IL-1beta caused a dose-related reduction of luciferase activity in Caco-2 cells transfected with the full-length GSTA1 promoter-luciferase construct. Using truncated constructs, IL-1beta responsiveness was mapped to a region 286 base pairs upstream to the coding region. Deletion of a hepatic nuclear factor 1 (HNF-1) site in this region abrogated the IL-1beta-mediated repression of GSTA1 promoter activity. These results demonstrate that IL-1beta down-regulates GSTA1/A2 expression in cultured human enterocytes by a transcriptional mechanism involving an HNF-1 site.
Romero
Laura
L
Department of Biomedical Sciences, University of Guelph, Guelph, Ontario, Canada.
Higgins
Marnie A
MA
Gilmore
James
J
Boudreau
Kim
K
Maslen
Ann
A
Barker
Heather J
HJ
Kirby
Gordon M
GM
D001426:Bacterial Proteins; D015152:Blotting, Northern; D018938:Caco-2 Cells; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D002470:Cell Survival / Q000187:drug effects; D004268:DNA-Binding Proteins; D015536:Down-Regulation / Q000187:drug effects; D020895:Enterocytes / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D005982:Glutathione Transferase; D051537:Hepatocyte Nuclear Factor 1; D051538:Hepatocyte Nuclear Factor 1-alpha; D051539:Hepatocyte Nuclear Factor 1-beta; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D008156:Luciferases / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins; D010957:Plasmids / Q000235:genetics; D012313:RNA / Q000096:biosynthesis / Q000235:genetics; D014157:Transcription Factors / Q000494:pharmacology; D014162:Transfection
D001426:Bacterial Proteins; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C105760:GstA protein, bacteria; C496487:HNF1A protein, human; C496495:HNF1B protein, human; D051538:Hepatocyte Nuclear Factor 1-alpha; D007375:Interleukin-1; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D014157:Transcription Factors; D051537:Hepatocyte Nuclear Factor 1; D051539:Hepatocyte Nuclear Factor 1-beta; D012313:RNA; D008156:Luciferases; C484555:GSTA1 protein, human; D005982:Glutathione Transferase