A Reconfigured Pattern of MLL Occupancy Within Mitotic Chromatin Promotes Rapid Transcriptional Reactivation Following Mitotic Exit

Mol Cell. 2009 Dec 25;36(6):970-83. doi: 10.1016/j.molcel.2009.12.001.


Mixed lineage leukemia (MLL) and its metazoan Trithorax orthologs have been linked with the epigenetic maintenance of transcriptional activity. To identify mechanisms by which MLL perpetuates active transcription in dividing cells, we investigated its role during M phase of the cell cycle. Unlike other chromatin-modifying enzymes examined, we found that MLL associates with gene promoters packaged within condensed mitotic chromosomes. Genome-wide location analysis identified a globally rearranged pattern of MLL occupancy during mitosis in a manner favoring genes that were highly transcribed during interphase. Knockdown experiments revealed that MLL retention at gene promoters during mitosis accelerates transcription reactivation following mitotic exit. MLL tethers Menin, RbBP5, and ASH2L to its occupied sites during mitosis, but is dispensable for preserving histone H3K4 methylation. These findings implicate mitotic bookmarking as a component of Trithorax-based gene regulation, which may facilitate inheritance of active gene expression states during cell division.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Chromatin / genetics
  • Chromatin / metabolism*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Gene Expression Regulation
  • HeLa Cells
  • Histone-Lysine N-Methyltransferase / genetics
  • Histone-Lysine N-Methyltransferase / metabolism
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism
  • Humans
  • Interphase / genetics
  • Mitosis / physiology*
  • Myeloid-Lymphoid Leukemia Protein / genetics
  • Myeloid-Lymphoid Leukemia Protein / metabolism*
  • Neoplasm Proteins / genetics
  • Neoplasm Proteins / metabolism
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism
  • Promoter Regions, Genetic
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism
  • RNA Interference
  • RNA Polymerase II / genetics
  • RNA Polymerase II / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Transcriptional Activation*


  • ASH2L protein, human
  • Chromatin
  • DNA-Binding Proteins
  • Homeodomain Proteins
  • KMT2D protein, human
  • MEN1 protein, human
  • Neoplasm Proteins
  • Nuclear Proteins
  • Proto-Oncogene Proteins
  • RBBP5 protein, human
  • Transcription Factors
  • Myeloid-Lymphoid Leukemia Protein
  • Histone-Lysine N-Methyltransferase
  • Setd1A protein, human
  • RNA Polymerase II