TY - JOUR
T1 - Egr-1 mediates transcriptional repression of COL2A1 promoter activity by interleukin-1β
AU - Tan, Lujian
AU - Peng, Haibing
AU - Osaki, Makoto
AU - Choy, Bob K.
AU - Auron, Philip E.
AU - Sandell, Linda J.
AU - Goldring, Mary B.
PY - 2003/5/16
Y1 - 2003/5/16
N2 - Following induction and activation of the early growth response (Egr)-1 transcription factor in human chondrocytes, interleukin-1β (IL-1β) 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-1β-induced Egr-1 binds strongly to the -119/-112 bp site, and mutations that block Egr-1 binding prevent inhibition by IL-1β. Cotransfection with pCMV-Egr1 potentiates the inhibition of COL2A1 promoter activity by IL-1β, whereas overexpression of dominant-negative Egr-1 mutant, Wilm's tumor-1 (WT1)/Egr1, Sp1, or Sp3 reverses the inhibition by IL-1β. 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-1β that is reversed by overexpression of Gal4-CBP. Our results indicate that IL-1β-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.
AB - Following induction and activation of the early growth response (Egr)-1 transcription factor in human chondrocytes, interleukin-1β (IL-1β) 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-1β-induced Egr-1 binds strongly to the -119/-112 bp site, and mutations that block Egr-1 binding prevent inhibition by IL-1β. Cotransfection with pCMV-Egr1 potentiates the inhibition of COL2A1 promoter activity by IL-1β, whereas overexpression of dominant-negative Egr-1 mutant, Wilm's tumor-1 (WT1)/Egr1, Sp1, or Sp3 reverses the inhibition by IL-1β. 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-1β that is reversed by overexpression of Gal4-CBP. Our results indicate that IL-1β-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.
UR - http://www.scopus.com/inward/record.url?scp=0038381435&partnerID=8YFLogxK
U2 - 10.1074/jbc.M301676200
DO - 10.1074/jbc.M301676200
M3 - Article
C2 - 12637574
AN - SCOPUS:0038381435
SN - 0021-9258
VL - 278
SP - 17688
EP - 17700
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 20
ER -