Department of Cell Biology
Cell Biology | Life Sciences | Medicine and Health Sciences
The activation of muscle-specific gene expression requires the coordinated action of muscle regulatory proteins and chromatin-remodeling enzymes. Microarray analysis performed in the presence or absence of a dominant-negative BRG1 ATPase demonstrated that approximately one-third of MyoD-induced genes were highly dependent on SWI/SNF enzymes. To understand the mechanism of activation, we performed chromatin immunoprecipitations analyzing the myogenin promoter. We found that H4 hyperacetylation preceded Brg1 binding in a MyoD-dependent manner but that MyoD binding occurred subsequent to H4 modification and Brg1 interaction. In the absence of functional SWI/SNF enzymes, muscle regulatory proteins did not bind to the myogenin promoter, thereby providing evidence for SWI/SNF-dependent activator binding. We observed that the homeodomain factor Pbx1, which cooperates with MyoD to stimulate myogenin expression, is constitutively bound to the myogenin promoter in a SWI/SNF-independent manner, suggesting a two-step mechanism in which MyoD initially interacts indirectly with the myogenin promoter and attracts chromatin-remodeling enzymes, which then facilitate direct binding by MyoD and other regulatory proteins.
DOI of Published Version
Mol Cell Biol. 2005 May;25(10):3997-4009. Link to article on publisher's site
Molecular and cellular biology
de la Serna, Ivana L.; Ohkawa, Yasuyuki; Berkes, Charlotte A.; Bergstrom, Donald A.; Dacwag, Caroline S.; Tapscott, Stephen J.; and Imbalzano, Anthony N., "MyoD targets chromatin remodeling complexes to the myogenin locus prior to forming a stable DNA-bound complex" (2005). GSBS Student Publications. 264.