The adenoviral E1A oncoprotein activates the Smad7 promoter: Requirement of a functional E-box
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- Published online on: December 1, 2009 https://doi.org/10.3892/ijo_00000468
- Pages: 1493-1498
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Abstract
DNA tumorviruses like adenoviruses (AdV) or human papillomaviruses (HPV) have adopted various strategies to interfere with antiproliferative transforming growth factor-β (TGF-β) signalling. Here we report that the AdV E1A oncoprotein is sufficient to induce Smad7 expression, an inhibitor of TGF-β signalling. E1A but not HPV oncoproteins activated the Smad7 promoter. A promoter proximal E-box was crucial for E1A-mediated transcriptional activity. E1A but not HPV oncoproteins induced specific binding activity at this E-box, which was identified as upstream stimulatory factor. In conclusion, these results unravel a novel mechanism of how the AdV E1A oncoprotein induces a cellular inhibitor of TGF-β signalling.