title: Inverse correlation between metallothioneins and hypoxia-inducible factor 1 alpha in colonocytes and experimental colitis.
abstract: A positive-feedback mechanism between hypoxia-inducible factor 1 alpha (HIF-1α) and metallothioneins (MTs) has been identified in different diseases. Both proteins have been independently proposed in the pathogenesis of inflammatory bowel disease (IBD); however, their relation has never been studied in the gut. In this study, we investigated the interaction between HIF-1α and MTs in colonic epithelial cells and during experimental colitis. Dimethyloxalylglycine (DMOG) was used to subject colonocytes to hydroxylase inhibition and HIF-1α stabilization in three experimental models (in vitro, in vivo and ex vivo). Small interfering RNA targeting HIF-1α (siRNA-HIF) and MT (siRNA-MT) together with zinc-mediated MT induction were used to study the interaction between HIF-1α and MT in HT29 cells. Acute colitis was induced in C57BL/6 mice using dextran sulphate sodium. MT expression and HIF-1α protein levels were measured using quantitative real-time PCR and ELISA, respectively. Vascular endothelial growth factor (VEGF) expression was quantified as an indirect measure of HIF-1 transcriptional activity. DMOG down-regulated MT expression in HT29 cells, in freshly isolated human colonocytes and in colonocytes isolated from mice treated with DMOG (p<0.05). SiRNA-HIF-treated cells displayed significant higher basal MT levels (p<0.05) and an attenuated MT down-regulation after DMOG treatment. In turn, HIF-1α stabilization was significantly lower in zinc-treated control cells, displaying high MT levels, compared to siRNA-MT cells treated with DMOG (p<0.05). In the course of experimental colitis, MT and VEGF mRNA expression were inversely related. MTs were induced in the acute phase and down-regulated during recovery. Opposing results were observed for VEGF expression levels (p<0.05). The present study underscores the inverse relation between HIF-1α and MT expression in colonocytes and during experimental colitis. The manipulation of MTs may represent a novel therapeutic strategy for patients suffering from IBD.
authors: Department of Gastroenterology, Ghent University, De Pintelaan 185, 1K12IE, B-9000 Ghent, Belgium. lindsey.devisscher@ugent.be
authors: Lindsey
authors: L
authors: Devisscher
authors: Pieter
authors: P
authors: Hindryckx
authors: Kim
authors: K
authors: Olievier
authors: Harald
authors: H
authors: Peeters
authors: Martine
authors: M
authors: De Vos
authors: Debby
authors: D
authors: Laukens
mesh_terms: D000600:Amino Acids, Dicarboxylic / Q000494:pharmacology; D000818:Animals; D003092:Colitis / Q000139:chemically induced; D003106:Colon / Q000187:drug effects / Q000378:metabolism*; D015536:Down-Regulation; D019073:HT29 Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism*; D015212:Inflammatory Bowel Diseases / Q000139:chemically induced / Q000378:metabolism*; D008668:Metallothionein / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D034741:RNA, Small Interfering / Q000235:genetics; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism; D015032:Zinc / Q000494:pharmacology
chemical_list: D000600:Amino Acids, Dicarboxylic; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D034741:RNA, Small Interfering; D042461:Vascular Endothelial Growth Factor A; D008668:Metallothionein; D015032:Zinc; C040947:oxalylglycine