Identification of new sites of binding and activation of the murine alpha1(I) collagen promoter by CCAAT/enhancer binding protein beta.
The CCAAT/enhancer binding protein beta (C/EBPbeta) was previously shown to bind to the alpha(1)(I) collagen promoter at -365 to -335 (site 1) and to activate it. Acetaldehyde also activates the promoter, and this effect is mediated by an increase in stellate-cell C/EBPbeta protein and C/EBPbeta binding. The present study identified two additional distal sites (sites 2 and 3) of binding of C/EBPbeta, in the nuclear extracts of stellate cells, at -399 to -370 and -623 to -592 in the alpha(1)(I) collagen promoter. The C/EBPbeta protein activates the promoter at all three sites. Acetaldehyde increases C/EBPbeta binding to all three sites. Activation by acetaldehyde is abrogated in the transfected promoter mutated at either site 1 or site 3 but is not affected by mutation at site 2. Binding of the 20-kDa C/EBPbeta isoform (p20C/EBPbeta), which is eliminated by mutation at the distal site 3 of C/EBP binding, is necessary for the activation by acetaldehyde of the alpha(1)(I) collagen promoter.
Attard
F A
FA
Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205-2195, USA.
Wang
L
L
Potter
J J
JJ
Rennie-Tankersley
L
L
Mezey
E
E
D000818:Animals; D001665:Binding Sites; D022782:CCAAT-Enhancer-Binding Protein-beta / Q000378:metabolism*; D003094:Collagen / Q000235:genetics*; D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D008297:Male; D051379:Mice; D011401:Promoter Regions, Genetic; D051381:Rats; D017207:Rats, Sprague-Dawley; D015533:Transcriptional Activation / Q000187:drug effects
D022782:CCAAT-Enhancer-Binding Protein-beta; D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D003094:Collagen