Regulation of expression of the rat serine protease inhibitor 2.3 gene by glucocorticoids and interleukin-6. A complex and unusual interplay between positive and negative cis-acting elements.
The rat serine protease inhibitor 2.3 gene (spi 2.3) is almost completely silent in normal animals and is transiently expressed during acute inflammation. It encodes a potential anti-elastase which is likely to play a major physiological role for the host defense. Two well-known inflammatory mediators, glucocorticoids and interleukin-6 (IL-6) activate the spi 2.3 promoter and increase steady-state levels of mRNA in cultured hepatocytes. GC activation is mediated by a single glucocorticoid-response element which seems to act autonomously. A unique array of four functional IL-6-response sites was identified in the spi 2.3 promoter. Three of them (C-II--IV) bear structural identity to the CCAAT/enhancer-binding-protein-binding site consensus sequence, whereas the fourth closely resembles the consensus kappa B nuclear factor recognition motif. The C-IV element, which is the most active, contains the motif 5'-CTGGGA and binds the IL-6-inducible acute-phase response factor present in liver nuclear extracts from inflamed rats. Both basal and IL-6-dependent activities of each individual cytokine-response element tested separately are strongly down regulated by a recently identified regulatory sequence, located in the 3' untranslated region of the spi 2.3 gene. However, this repressor element does not significantly affect overall IL-6-dependent spi 2.3 promoter activity. This suggests that, in the context of the active gene in vivo, all four IL-6-response sites, which are largely redundant, cooperate to overcome the strong repressive effect of the 3' untranslated region silencer and are needed to bring about a maximal IL-6 response. These data reveal a novel type of regulation of an acute-phase gene involving different classes of IL-6-response elements controlled by a repressor and acting in conjunction with a glucocorticoid-response element.
Simar-Blanchet
A E
AE
INSERM U-376, hôpital Arnaud de Villeneuve, Montpellier, France.
Paul
C
C
Mercier
L
L
Le Cam
A
A
D000818:Animals; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D005938:Glucocorticoids / Q000494:pharmacology*; D007249:Inflammation / Q000201:enzymology; D015850:Interleukin-6 / Q000494:pharmacology*; D008099:Liver; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017384:Sequence Deletion; D015842:Serine Proteinase Inhibitors / Q000235:genetics*; D015843:Serpins
D004268:DNA-Binding Proteins; D005938:Glucocorticoids; D015850:Interleukin-6; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D015842:Serine Proteinase Inhibitors; C050936:Serpina3c protein, rat; D015843:Serpins; D003907:Dexamethasone