MLL Repression Domain Interacts with Histone Deacetylases, the Polycomb Group Proteins HPC2 and BMI-1, and the Corepressor C-Terminal-Binding Protein

• Published in: Proceedings of the National Academy of Sciences - PNAS 2003-07, Vol.100 (14), p.8342-8347
• Main Authors: Xia, Zhen-Biao, Anderson, Melanie, Diaz, Manuel O., Zeleznik-Le, Nancy J.
• Format: Article
• Language: English
• Subjects: Alcohol Oxidoreductases; Amino Acid Motifs; Antibodies; Biological Sciences; Cell Line - metabolism; Co repressor proteins; Cyclophilins - physiology; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - metabolism; HeLa cells; Histone Deacetylase 1; Histone Deacetylases - metabolism; Histone-Lysine N-Methyltransferase; Histones; Humans; Kidney - cytology; Kidney - embryology; Leukemia; Ligases; Mathematical functions; Myeloid-Lymphoid Leukemia Protein; Nuclear Proteins - metabolism; Phosphoproteins - metabolism; Polycomb Repressive Complex 1; Polycomb-Group Proteins; Protein Interaction Mapping; Protein Structure, Tertiary; Proteins; Proto-Oncogene Proteins - metabolism; Proto-Oncogenes; Recombinant Fusion Proteins - metabolism; Reporter genes; Repression; Repressor Proteins - chemistry; Repressor Proteins - metabolism; Transcription Factors; Transcription, Genetic; Transfection; Ubiquitin-Protein Ligases
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1436338100

The MLL (mixed-lineage leukemia) gene is involved in many chromosomal translocations associated with acute myeloid and lymphoid leukemia. We previously identified a transcriptional repression domain in MLL, which contains a region with homology to DNA methyltransferase. In chromosomal translocations, the MLL repression domain is retained in the leukemogenic fusion protein and is required for transforming activity of MLL fusion proteins. We explored the mechanism of action of the MLL repression domain. Histone deacetylase 1 interacts with the MLL repression domain, partially mediating its activity; binding of Cyp33 to the adjacent MLL-PHD domain potentiates this binding. Because the MLL repression domain activity was only partially relieved with the histone deacetylase inhibitor trichostatin A, we explored other protein interactions with this domain. Polycomb group proteins HPC2 and BMI-1 and the corepressor C-terminal-binding protein also bind the MLL repression domain. Expression of exogenous BMI-1 potentiates MLL repression domain activity. Functional antagonism between Mll and Bmi-1 has been shown genetically in murine knockout models for Mll and Bmi-1. Our new data suggest a model whereby recruitment of BMI-1 to the MLL protein may be able to modulate its function. Furthermore, repression mediated by histone deacetylases and that mediated by polycomb group proteins may act either independently or together for MLL function in vivo.