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The BRCT-domain containing protein PTIP links PAX2 to a histone H3, lysine 4 methyltransferase complex

Sanjeevkumar R Patel1, Doyeob Kim, Inna Levitan

  • 1Department of Medicine, University of Michigan, Ann Arbor, MI 48109, USA.

Developmental Cell
|October 11, 2007
PubMed

Insights

The study reveals that PTIP (pax transcription activation domain interacting protein) bridges DNA-binding proteins like PAX2 to histone methyltransferase complexes. This interaction is crucial for maintaining active chromatin and H3K4 methylation during development.

Area of Science:

  • Epigenetics
  • Molecular Biology
  • Developmental Biology

Background:

  • The MLL (mixed-lineage leukemia) family of histone methyltransferases is vital for maintaining active chromatin by methylating histone H3 on lysine 4 (H3K4).
  • The mechanisms by which MLL complexes recognize specific chromatin domains in a temporal and tissue-specific manner are not fully understood.

Purpose of the Study:

  • To investigate how DNA-binding proteins interact with histone methyltransferase complexes.
  • To elucidate the role of PTIP (pax transcription activation domain interacting protein) in bridging developmental regulators to epigenetic machinery.

Main Methods:

  • Co-immunoprecipitation to identify protein interactions.
  • Analysis of histone H3K4 methylation levels in wild-type and mutant organisms.
  • Studies using embryonic lethal ptip-null and conditional mutant models.

Main Results:

  • PAX2, a DNA-binding protein, recruits PTIP to facilitate the assembly of an H3K4 methyltransferase complex.
  • PTIP is essential for the assembly of the ALR complex and subsequent H3K4 methylation at PAX2-bound DNA elements.
  • Loss of PTIP function leads to reduced H3K4 methylation levels, impacting embryonic development.

Conclusions:

  • PTIP acts as a crucial molecular bridge, connecting DNA-binding developmental regulators like PAX2 to the histone methyltransferase machinery.
  • This interaction is fundamental for establishing and maintaining active chromatin states through H3K4 methylation.
  • The findings provide new insights into the epigenetic regulation of gene expression during development.

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