title: Egr-1 mediates transcriptional repression of COL2A1 promoter activity by interleukin-1beta.
abstract: Following induction and activation of the early growth response (Egr)-1 transcription factor in human chondrocytes, interleukin-1beta (IL-1beta) suppresses the expression of the type II collagen gene (COL2A1), associated with induction of Egr-1 binding activity in nuclear extracts. The COL2A1 proximal promoter contains overlapping binding sites for Egr-1 and Sp1 family members at -119/-112 bp and -81/-74 bp. Mutations that block binding of Sp1 and Sp3 to either site markedly reduce constitutive expression of the core promoter. IL-1beta-induced Egr-1 binds strongly to the -119/-112 bp site, and mutations that block Egr-1 binding prevent inhibition by IL-1beta. Cotransfection with pCMV-Egr1 potentiates the inhibition of COL2A1 promoter activity by IL-1beta, whereas overexpression of dominant-negative Egr-1 mutant, Wilm's tumor-1 (WT1)/Egr1, Sp1, or Sp3 reverses the inhibition by IL-1beta. Cotransfection of pGL2-COL2/Gal4, in which we substituted the critical residue for Egr-1 binding with a Gal4 binding domain and a pCMV-Gal4-Egr1 chimera permits an inhibitory response to IL-1beta that is reversed by overexpression of Gal4-CBP. Our results indicate that IL-1beta-induced activation of Egr-1 binding is required for inhibition of COL2A1 proximal promoter activity and suggest that Egr-1 acts as a repressor of a constitutively expressed collagen gene by preventing interactions between Sp1 and the general transcriptional machinery.
authors.affiliation: Rheumatology Division, Beth Israel Deaconess Medical Center and New England Baptist Bone & Joint Institute, Harvard Institutes of Medicine, Boston, Massachusetts 02115, USA.
authors.forename: Lujian
authors.initials: L
authors.lastname: Tan
authors.forename: Haibing
authors.initials: H
authors.lastname: Peng
authors.forename: Makoto
authors.initials: M
authors.lastname: Osaki
authors.forename: Bob K
authors.initials: BK
authors.lastname: Choy
authors.forename: Philip E
authors.initials: PE
authors.lastname: Auron
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Sandell
authors.forename: Mary B
authors.initials: MB
authors.lastname: Goldring
mesh_terms: D020816:Amino Acid Motifs; D001665:Binding Sites; D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D019902:Chondrocytes / Q000378:metabolism; D003094:Collagen / Q000378:metabolism; D024043:Collagen Type II / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D051766:Early Growth Response Protein 1; D006801:Humans; D017874:Immediate-Early Proteins; D007375:Interleukin-1 / Q000378:metabolism*; D008156:Luciferases / Q000378:metabolism; D008957:Models, Genetic; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D016329:Sp1 Transcription Factor / Q000378:metabolism; D013997:Time Factors; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection
chemical_list: C499177:COL2A1 protein, human; D024043:Collagen Type II; D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; C486109:Egr1 protein, mouse; D017874:Immediate-Early Proteins; D007375:Interleukin-1; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D012313:RNA; D003094:Collagen; D008156:Luciferases