Chromatin immunoprecipitation on microarray analysis of Smad2/3 binding sites reveals roles of ETS1 and TFAP2A in transforming growth factor β signaling

D Koinuma, S Tsutsumi, N Kamimura… - … and cellular biology, 2009 - Taylor & Francis
D Koinuma, S Tsutsumi, N Kamimura, H Taniguchi, K Miyazawa, M Sunamura, T Imamura…
Molecular and cellular biology, 2009Taylor & Francis
The Smad2 and Smad3 (Smad2/3) proteins are principally involved in the transmission of
transforming growth factor β (TGF-β) signaling from the plasma membrane to the nucleus.
Many transcription factors have been shown to cooperate with the Smad2/3 proteins in
regulating the transcription of target genes, enabling appropriate gene expression by cells.
Here we identified 1,787 Smad2/3 binding sites in the promoter regions of over 25,500
genes by chromatin immunoprecipitation on microarray in HaCaT keratinocytes. Binding …
The Smad2 and Smad3 (Smad2/3) proteins are principally involved in the transmission of transforming growth factor β (TGF-β) signaling from the plasma membrane to the nucleus. Many transcription factors have been shown to cooperate with the Smad2/3 proteins in regulating the transcription of target genes, enabling appropriate gene expression by cells. Here we identified 1,787 Smad2/3 binding sites in the promoter regions of over 25,500 genes by chromatin immunoprecipitation on microarray in HaCaT keratinocytes. Binding elements for the v-ets erythroblastosis virus E26 oncogene homolog (ETS) and transcription factor AP-2 (TFAP2) were significantly enriched in Smad2/3 binding sites, and knockdown of either ETS1 or TFAP2A resulted in overall alteration of TGF-β-induced transcription, suggesting general roles for ETS1 and TFAP2A in the transcription induced by TGF-β-Smad pathways. We identified novel Smad binding sites in the CDKN1A gene where Smad2/3 binding was regulated by ETS1 and TFAP2A. Moreover, we showed that small interfering RNAs for ETS1 and TFAP2A affected TGF-β-induced cytostasis. We also analyzed Smad2- or Smad3-specific target genes regulated by TGF-β and found that their specificity did not appear to be solely determined by the amounts of the Smad2/3 proteins bound to the promoters. These findings reveal novel regulatory mechanisms of Smad2/3-induced transcription and provide an essential resource for understanding their roles.
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