Sanjeevkumar R. Patel,1 Doyeob Kim,2 Inna Levitan,2 and Gregory R. Dressler2*
1Departments of Medicine, University of Michigan, Ann Arbor, MI 48109.
2Pathology, University of Michigan, Ann Arbor, MI 48109.
*Corresponding address: 2049 BSRB 109 Zina Pitcher Place Ann Arbor, MI 48109 Email: email@example.com 734−764−6490
Active or repressed chromatin domains are established during development by epigenetic imprinting mechanisms that modify chromatin. The MLL family of histone methyltransferases maintain active chromatin domains by histone H3, lysine 4 methylation. How MLL complexes recognize specific chromatin domains in a temporal and tissue specific manner remains unclear. We show that the DNA binding protein Pax2 promotes assembly of an H3K4 methyltransferase complex through the ubiquitously expressed nuclear factor PTIP (Pax Transcription activation domain Interacting Protein). PTIP co-purifies with ALR, MLL3, and other components of a histone methyltransferase complex. The PTIP promotes assembly of the ALR complex and H3K4 methylation at a Pax2 DNA recognition sequence. Without PTIP, Pax2 binds to its recognition sequence but does not assemble the ALR complex. Embryonic lethal PTIP null mutants and conditional mutants both show reduced levels of methylated H3K4. Thus, PTIP is a novel component of a histone methyltransferase complex that links DNA binding developmental regulators to epigenetic imprinting.
Keywords: PTIP, Pax2, Histone Methyltransferase, ALR, Epigenetics