Characterization of cis-regulatory elements conferring mercury-induced interleukin-4 gene expression in rat mast cells: a role for signal transducer and activator of transcription 6 and TATA box binding sites.
We have previously shown that oxidative stress is involved in the pathogenesis of a mercuric chloride (HgCl(2))-induced, T helper type 2 (Th2)-driven autoimmune syndrome in Brown Norway (BN) rats. In the context of the syndrome, the oxidative stress-induced mast cell response seems to determine the development of the early phase of vasculitis, while oxidative stress-mediated interleukin (IL)-4 production may contribute to the subsequent Th2-driven autoimmune response. However, the molecular basis of IL-4 gene transcription induced by HgCl(2) in mast cells remains unknown. In the present study, we dissect the critical regulatory mechanisms in the IL-4 gene promoter in the rat mast cell line RBL-2H3. Immunoprecipitation provided evidence that treatment with HgCl(2) increased phosphorylation of signal transducer and activator of transcription 6 (STAT6). Transient transfection reporter analyses with a series of 5' end deletions of the IL-4 promoter produced evidence that STAT6 and TATA box binding sites are important in HgCl(2)-induced IL-4 gene expression. Subsequent elimination of one or both sites by site-directed mutagenesis significantly inhibited IL-4 promoter activity. Our results provide evidence that STAT6 and TATA box regulatory elements play an important role in HgCl(2)-induced IL-4 transcription in rat mast cells.
Wu
Zonglin
Z
Department of Cellular and Molecular Medicine, St George's Hospital Medical School, London, UK.
Pearson
Alex
A
Oliveira
David
D
D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000276:immunology; D015847:Interleukin-4 / Q000096:biosynthesis* / Q000235:genetics; D008407:Mast Cells / Q000187:drug effects* / Q000276:immunology; D008627:Mercuric Chloride / Q000494:pharmacology*; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000187:drug effects; D051381:Rats; D050800:STAT6 Transcription Factor / Q000502:physiology*; D035181:TATA-Box Binding Protein / Q000502:physiology; D014162:Transfection; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology
D050800:STAT6 Transcription Factor; D035181:TATA-Box Binding Protein; D015847:Interleukin-4; D008627:Mercuric Chloride