TNF-alpha suppressed TGF-beta-induced CTGF expression by switching the binding preference of p300 from Smad4 to p65.
TGF-beta regulates diverse biologic effects including cell growth, cell death or apoptosis, cell differentiation, and extracellular matrix (ECM) synthesis. Connective tissue growth factor (CTGF), induced by TGF-beta has been reported to mediate stimulatory action of TGF-beta-induced ECM. Although TNF-alpha was reported to suppress theTGF-beta-induced CTGF gene expression, the molecular mechanism is not well clarified. In this study, we found the inhibitory effect of TNF-alpha on TGF-beta-induced CTGF expression in WT but not p65-/-MEF cells. TNF-alpha neither induced Smad7 expression nor affected TGF-beta-induced Smad2 phosphorylation and nuclear translocation. We demonstrated that p300 physically associated with p65 rather than Smad4 in the presence of both TNF-alpha and TGF-beta. Moreover, the TGF-beta-induced binding of p300 and acetylated H4, but not Smad4 to the CTGF promoter was disturbed by TNF-alpha treatment. Overall, our data showed that suppression of TNF-alpha on TGF-beta-induced CTGF expression is due to the competition of p300 by p65 and Smad4.
Yu
Fun
F
Department of Pharmacology, College of Medicine, National Taiwan University, No. 1 Jen-Ai Road, Taipei, Taiwan.
Chou
Chia-Wei
CW
Chen
Ching-Chow
CC
D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D055513:Connective Tissue Growth Factor / Q000235:genetics / Q000378:metabolism*; D050881:E1A-Associated p300 Protein / Q000378:metabolism*; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism; D051379:Mice; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D051899:Smad2 Protein / Q000378:metabolism; D051900:Smad3 Protein / Q000378:metabolism; D051901:Smad4 Protein / Q000378:metabolism*; D051996:Transcription Factor RelA / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D051899:Smad2 Protein; C497783:Smad2 protein, mouse; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D051901:Smad4 Protein; C490810:Smad4 protein, mouse; D051996:Transcription Factor RelA; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; D055513:Connective Tissue Growth Factor; D050881:E1A-Associated p300 Protein; C494361:Ep300 protein, mouse; D051550:I-kappa B Kinase