Myogenin recruits the histone chaperone facilitates chromatin transcription (FACT) to promote nucleosome disassembly at muscle-specific genes.
Facilitates chromatin transcription (FACT) functions to reorganize nucleosomes by acting as a histone chaperone that destabilizes and restores nucleosomal structure. The FACT complex is composed of two subunits: SSRP1 and SPT16. We have discovered that myogenin interacts with the FACT complex. Transfection of FACT subunits with myogenin is highly stimulatory for endogenous muscle gene expression in 10T1/2 cells. We have also found that FACT subunits do not associate with differentiation-specific genes while C2C12 cells are proliferating but are recruited to muscle-specific genes as differentiation initiates and then dissociate as differentiation proceeds. The recruitment is dependent on myogenin, as knockdowns of myogenin show no recruitment of the FACT complex. These data suggest that FACT is involved in the early steps of gene activation through its histone chaperone activities that serve to open the chromatin structure and facilitate transcription. Consistent with this hypothesis, we find that nucleosomes are depleted at muscle-specific promoters upon differentiation and that this activity is dependent on the presence of FACT. Our results show that the FACT complex promotes myogenin-dependent transcription and suggest that FACT plays an important role in the establishment of the appropriate transcription profile in a differentiated muscle cell.
Department of Biochemistry and Molecular Biology and Simmons Cancer Institute, Southern Illinois University, School of Medicine, Carbondale, Illinois 62901.
Alexandra A
AA
Lolis
Department of Biochemistry and Molecular Biology and Simmons Cancer Institute, Southern Illinois University, School of Medicine, Carbondale, Illinois 62901.
Priya
P
Londhe
Department of Biochemistry and Molecular Biology and Simmons Cancer Institute, Southern Illinois University, School of Medicine, Carbondale, Illinois 62901.
Benjamin C
BC
Beggs
Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Science, Little Rock, Arkansas 72205.
Stephanie D
SD
Byrum
Department of Biochemistry and Molecular Biology, University of Arkansas for Medical Science, Little Rock, Arkansas 72205.
Alan J
AJ
Tackett
Department of Biochemistry and Molecular Biology and Simmons Cancer Institute, Southern Illinois University, School of Medicine, Carbondale, Illinois 62901. Electronic address: jdavie@siumed.edu.
Judith K
JK
Davie
D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism*; D042002:Chromatin Assembly and Disassembly; D004260:DNA Repair; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006657:Histones / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D051379:Mice; D024510:Muscle Development; D018482:Muscle, Skeletal / Q000378:metabolism; D009132:Muscles / Q000378:metabolism; D017570:MyoD Protein / Q000378:metabolism; D018008:Myogenin / Q000378:metabolism / Q000502:physiology*; D009707:Nucleosomes / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D014162:Transfection
D002843:Chromatin; D006657:Histones; D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; D018008:Myogenin; D009707:Nucleosomes