IL-1 beta-dependent regulation of C/EBP delta transcriptional activity.
We have previously shown that the transcription factor C/EBP delta is involved in the intestinal inflammatory response. C/EBP delta regulates several inflammatory response genes, such as haptoglobin, in the rat intestinal epithelial cell line IEC-6 in response to IL-1. However, the different C/EBP delta domains involved in IL-1 beta-mediated transcriptional activation and the kinases implicated have not been properly defined. To address this, we determined the role of the p38 MAP kinase in the regulation of C/EBP delta transcriptional activity. The IL-1-dependent induction of the acute phase protein gene haptoglobin in IEC-6 cells was decreased in response to the p38 MAP kinase inhibitor SB203580, as determined by Northern blot. Transcriptional activity of C/EBP delta was repressed by the specific inhibitor of the p38 MAP kinase, as assessed by transient transfection assays. Mutagenesis studies and transient transfection assays revealed an important domain for transcriptional activation between amino acids 70 and 108. This domain overlapped with a docking site for the p38 MAP kinase, between amino acids 75 and 85, necessary to insure C/EBP delta phosphorylation. Deletion of this domain led to a decrease in basal transcriptional activity of C/EBP delta and in p300-dependent transactivation, as assessed by transient transfection assays, and in IL-1-dependent haptoglobin induction. This unusual arrangement of a kinase docking site within a transactivation domain may functionally be important for the regulation of C/EBP delta transcriptional activity.
Svotelis
Amy
A
CIHR Group on Functional Development and Physiopathology of the Digestive Tract, Département d'Anatomie et Biologie Cellulaire, Faculté de Médecine, Université de Sherbrooke, Que., Canada J1H 5N4.
Doyon
Geneviève
G
Bernatchez
Gérald
G
Désilets
Antoine
A
Rivard
Nathalie
N
Asselin
Claude
C
D000818:Animals; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects; D007375:Interleukin-1 / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D051381:Rats; D013329:Structure-Activity Relationship; D051742:Transcription Factor CHOP; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000187:drug effects* / Q000502:physiology; D048051:p38 Mitogen-Activated Protein Kinases / Q000737:chemistry / Q000378:metabolism*
D022762:CCAAT-Enhancer-Binding Proteins; C497251:Ddit3 protein, rat; D007375:Interleukin-1; D014157:Transcription Factors; D051742:Transcription Factor CHOP; D048051:p38 Mitogen-Activated Protein Kinases