Chromatin-bound p53 anchors activated Smads and the mSin3A corepressor to confer transforming-growth-factor-beta-mediated transcription repression.

Published

Journal Article

In hepatic cells, Smad and SnoN proteins converge with p53 to repress transcription of AFP, an oncodevelopmental tumor marker aberrantly reactivated in hepatoma cells. Using p53- and SnoN-depleted hepatoma cell clones, we define a mechanism for repression mediated by this novel transcriptional partnership. We find that p53 anchors activated Smads and the corepressor mSin3A to the AFP distal promoter. Sequential chromatin immunoprecipitation analyses and molecular modeling indicate that p53 and Smad proteins simultaneously occupy overlapping p53 and Smad regulatory elements to establish repression of AFP transcription. In addition to its well-known function in antagonizing transforming growth factor beta (TGF-beta) responses, we find that SnoN actively participates in AFP repression by positively regulating mSin3A protein levels. We propose that activation of TGF-beta signaling restores a dynamic interplay between p53 and TGF-beta effectors that cooperate to effectively target mSin3A to tumor marker AFP and reestablish transcription repression.

Full Text

Duke Authors

Cited Authors

  • Wilkinson, DS; Tsai, W-W; Schumacher, MA; Barton, MC

Published Date

  • March 2008

Published In

Volume / Issue

  • 28 / 6

Start / End Page

  • 1988 - 1998

PubMed ID

  • 18212064

Pubmed Central ID

  • 18212064

Electronic International Standard Serial Number (EISSN)

  • 1098-5549

International Standard Serial Number (ISSN)

  • 0270-7306

Digital Object Identifier (DOI)

  • 10.1128/MCB.01442-07

Language

  • eng