Pax7 activates myogenic genes by recruitment of a histone methyltransferase complex

• Published in: Nature cell biology Vol. 10; no. 1; pp. 77 - 84
• Main Authors: McKinnell, Iain W, Greenblatt, Jack F, Rudnicki, Michael A, Addicks, Gregory C, Dilworth, F. Jeffrey, Ishibashi, Jeff, Le Grand, Fabien, Punch, Vincent G. J
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.01.2008; Nature Publishing Group
• Subjects: Animals; Biomedical and Life Sciences; Cancer Research; Cell Biology; Cell Line; Chromatin - metabolism; Chromatin Immunoprecipitation; Developmental Biology; DNA binding proteins; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Electrophoresis, Polyacrylamide Gel; Flow Cytometry; Fluorescence; Gene Expression Regulation; Genes; Genetic aspects; Genetic regulation; Histone Methyltransferases; Histone-Lysine N-Methyltransferase - metabolism; Histones - metabolism; Immunoprecipitation; letter; Life Sciences; Mass spectrometry; Methylation; Methyltransferases; Mice; Mice, Inbred C57BL; Musculoskeletal system; Myeloid-Lymphoid Leukemia Protein - genetics; Myeloid-Lymphoid Leukemia Protein - metabolism; Myoblasts - cytology; Myoblasts - metabolism; Myogenic Regulatory Factor 5 - genetics; Myogenic Regulatory Factor 5 - metabolism; Nuclear Proteins - genetics; Nuclear Proteins - metabolism; Oligonucleotide Array Sequence Analysis; PAX7 Transcription Factor - genetics; PAX7 Transcription Factor - metabolism; Physiological aspects; Protein Binding; Protein Methyltransferases; Proteins; Proteins - genetics; Proteins - metabolism; Reverse Transcriptase Polymerase Chain Reaction; RNA, Small Interfering - genetics; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Stem Cells; Transcription Factors - genetics; Transcription Factors - metabolism; Transcription, Genetic; Canada; Ottawa Ontario Canada
• ISSN: 1465-7392; 1476-4679
• DOI: 10.1038/ncb1671

Satellite cells purified from adult skeletal muscle can participate extensively in muscle regeneration and can also re-populate the satellite cell pool, suggesting that they have direct therapeutic potential for treating degenerative muscle diseases. The paired-box transcription factor Pax7 is required for satellite cells to generate committed myogenic progenitors. In this study we undertook a multi-level approach to define the role of Pax7 in satellite cell function. Using comparative microarray analysis, we identified several novel and strongly regulated targets; in particular, we identified Myf5 as a gene whose expression was regulated by Pax7. Using siRNA, fluorescence-activated cell sorting (FACS) and chromatin immunoprecipitation (ChIP) studies we confirmed that Myf5 is directly regulated by Pax7 in myoblasts derived from satellite cells. Tandem affinity purification (TAP) and mass spectrometry were used to purify Pax7 together with its co-factors. This revealed that Pax7 associates with the Wdr5-Ash2L-MLL2 histone methyltransferase (HMT) complex that directs methylation of histone H3 lysine 4 (H3K4, refs 4-10). Binding of the Pax7-HMT complex to Myf5 resulted in H3K4 tri-methylation of surrounding chromatin. Thus, Pax7 induces chromatin modifications that stimulate transcriptional activation of target genes to regulate entry into the myogenic developmental programme.