1. Academic Validation
  2. PTIP associates with MLL3- and MLL4-containing histone H3 lysine 4 methyltransferase complex

PTIP associates with MLL3- and MLL4-containing histone H3 lysine 4 methyltransferase complex

  • J Biol Chem. 2007 Jul 13;282(28):20395-406. doi: 10.1074/jbc.M701574200.
Young-Wook Cho 1 Teresa Hong Sunhwa Hong Hong Guo Hong Yu Doyeob Kim Tad Guszczynski Gregory R Dressler Terry D Copeland Markus Kalkum Kai Ge
Affiliations

Affiliation

  • 1 Nuclear Receptor Biology Section, Clinical Endocrinology Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Abstract

PTIP, a protein with tandem BRCT domains, has been implicated in DNA damage response. However, its normal cellular functions remain unclear. Here we show that while ectopically expressed PTIP is capable of interacting with DNA damage response proteins including 53BP1, endogenous PTIP, and a novel protein PA1 are both components of a Set1-like Histone Methyltransferase (HMT) complex that also contains ASH2L, RBBP5, WDR5, hDPY-30, NCOA6, SET domain-containing HMTs MLL3 and MLL4, and substoichiometric amount of JmjC domain-containing putative Histone Demethylase UTX. PTIP complex carries robust HMT activity and specifically methylates lysine 4 (K4) on histone H3. Furthermore, PA1 binds PTIP directly and requires PTIP for interaction with the rest of the complex. Moreover, we show that hDPY-30 binds ASH2L directly. The evolutionarily conserved hDPY-30, ASH2L, RBBP5, and WDR5 likely constitute a subcomplex that is shared by all human Set1-like HMT complexes. In contrast, PTIP, PA1, and UTX specifically associate with the PTIP complex. Thus, in cells without DNA damage agent treatment, the endogenous PTIP associates with a Set1-like HMT complex of unique subunit composition. As histone H3 K4 methylation associates with active genes, our study suggests a potential role of PTIP in the regulation of gene expression.

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