Abstract
We examined whether TGF-fl affects the transactivation activity of Ets-1. TGF-beta augmented ets-1 mRNA expression and Ets-1 protein synthesis in ECV304 cells to the level equivalent to bFGF. When the DNA binding activity of Ets-1 protein was examined, bFGF was found to enhance DNA-Ets complex formation, whereas TGF-beta attenuated basal as well as bFGF-enhanced DNA-Ets complex formation. As a result, TGF-beta attenuated the promoter activity driven by Ets-1. The DNA binding of Ets-1 protein was enhanced by the initial 4-hour bFGF treatment and the subsequent 8-hour cycloheximide treatment. When TGF-beta replaced cycloheximide in the subsequent 8-hour treatment, TGF-beta inhibited this bFGF-enhanced DNA-Ets complex formation. When TGF-beta and cycloheximide were simultaneously added in the subsequent 8-hour treatment, the inhibitory effect of TGF-beta on bFGF-enhanced DNA-Ets complex formation was completely abolished. These results suggest the possibility that TGF-beta attenuates the transactivation activity of Ets-1 by inducing a protein that interferes with the binding of Ets-1 to the DNA binding site.
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