The induction of CCN2 by TGFbeta1 involves Ets-1.
CCN2 is encoded by an immediate-early gene induced in mesenchymal cells during the formation of blood vessels, bone and connective tissue. It plays key roles in cell adhesion and migration, as well as matrix remodeling. CCN2 is overexpressed in fibrosis, arthritis and cancer; thus, an understanding of how to control CCN2 expression is likely to have importance in developing therapies to combat these pathologies. Previously, we found that the promoter sequence GAGGAATG is important for Ccn2 gene regulation in NIH 3T3 fibroblasts. In this report, we show that this sequence mediates activation of the CCN2 promoter by the ETS family of transcription factors. Endogenous Ets-1 binds this element of the CCN2 promoter, and dominant negative Ets-1 and specific Ets-1 small interfering RNA block induction of CCN2 expression by TGFbeta. In the absence of added TGFbeta1, Ets-1, but not the related fli-1, synergizes with Smad 3 to activate the CCN2 promoter. Whereas the ability of transfected Ets-1 to activate the CCN2 promoter is dependent on protein kinase C (PKC), Ets-1 in the presence of co-transfected Smad3 does not require PKC, suggesting that the presence of Smad3 bypasses the requirement of Ets-1 for PKC to activate target promoter activity. Our results are consistent with the notion that Smad3 and Ets-1 cooperate in the induction of the CCN2 promoter by TGFbeta1. Antagonizing Ets-1 might be of benefit in attenuating CCN2 expression in fibrosis, arthritis and cancer, and may be useful in modulating the outcome of these disorders.
CIHR Group in Skeletal Development and Remodeling, Schulich School of Medicine and Dentistry, Dental Sciences Building, The University of Western Ontario, London, ON N6A 5C1, Canada.
Jonathan P
JP
Van Beek
Laura
L
Kennedy
Jason S
JS
Rockel
Suzanne M
SM
Bernier
Andrew
A
Leask
D000818:Animals; D001483:Base Sequence; D055513:Connective Tissue Growth Factor; D004357:Drug Synergism; D005786:Gene Expression Regulation / Q000187:drug effects* / Q000502:physiology; D017874:Immediate-Early Proteins / Q000235:genetics*; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics*; D051379:Mice; D041681:NIH 3T3 Cells; D011401:Promoter Regions, Genetic / Q000502:physiology; D050784:Proto-Oncogene Protein c-ets-1 / Q000235:genetics / Q000502:physiology; D051789:Proto-Oncogene Protein c-fli-1 / Q000235:genetics / Q000502:physiology; D051900:Smad3 Protein / Q000235:genetics / Q000502:physiology; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1
C526318:CCN2 protein, mouse; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D050784:Proto-Oncogene Protein c-ets-1; D051789:Proto-Oncogene Protein c-fli-1; D051900:Smad3 Protein; C508961:Tgfb1 protein, mouse; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D055513:Connective Tissue Growth Factor