TAZ controls Smad nucleocytoplasmic shuttling and regulates human embryonic stem-cell self-renewal

Nat Cell Biol. 2008 Jul;10(7):837-48. doi: 10.1038/ncb1748. Epub 2008 Jun 22.

Abstract

Transforming growth factor-beta (TGFbeta) family members regulate many developmental and pathological events through Smad transcriptional modulators. How nuclear accumulation of Smad is coupled to the transcriptional machinery is poorly understood. Here we demonstrate that in response to TGFbeta stimulation the transcriptional regulator TAZ binds heteromeric Smad2/3-4 complexes and is recruited to TGFbeta response elements. In human embryonic stem cells TAZ is required to maintain self-renewal markers and loss of TAZ leads to inhibition of TGFbeta signalling and differentiation into a neuroectoderm lineage. In the absence of TAZ, Smad2/3-4 complexes fail to accumulate in the nucleus and activate transcription. Furthermore, TAZ, which itself engages in shuttling, dominantly controls Smad nucleocytoplasmic localization and can be retained in the nucleus by transcriptional co-factors such as ARC105, a component of the Mediator complex. TAZ thus defines a hierarchical system regulating Smad nuclear accumulation and coupling to the transcriptional machinery.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus / physiology*
  • Animals
  • Cell Line
  • Cell Nucleus / metabolism
  • Embryonic Stem Cells / cytology
  • Embryonic Stem Cells / physiology*
  • Genes, Reporter
  • Humans
  • Mediator Complex
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism
  • Signal Transduction / physiology
  • Smad2 Protein / genetics
  • Smad2 Protein / metabolism*
  • Smad3 Protein / genetics
  • Smad3 Protein / metabolism*
  • Smad4 Protein / genetics
  • Smad4 Protein / metabolism*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transcription, Genetic
  • Transforming Growth Factor beta / metabolism

Substances

  • MED15 protein, human
  • Mediator Complex
  • RNA, Small Interfering
  • SMAD2 protein, human
  • Smad2 Protein
  • Smad3 Protein
  • Smad4 Protein
  • TAZ protein, human
  • Transcription Factors
  • Transforming Growth Factor beta