| Abstract: |
The homeodomain protein TG-interacting factor (TGIF) represses transcription by histone deacetylase-dependent and -independent means. Heterozygous mutations In human TGIF result in holoprosencephaly, a severe genetic disorder affecting craniofacial development, suggesting that TGIF is critical for normal development. After transforming growth factor beta (TGF beta) stimulation, Smad proteins enter the nucleus and form transcriptional activation complexes or interact with TGIF, which functions as a corepressor. The relative levels of Smad corepressors and coactivators present within the cell may determine the outcome of a TGF beta response. We show that TGIF interacts directly with the paired amphipathic alpha -helix 2 domain of the mSin3 corepressor, and TGIF recruits mSin3 to a TGF beta -activated Smad complex. The mSin3 interaction domain of TGIF has been shown to be essential for repression of a TGF beta transcriptional response. Thus, TGIF represents a targeting component of the mSin3 corepressor complex. |
