Differentiation-specific expression of chromatin remodeling factor BRM.

The chromatin remodeling complex SWI/SNF exclusively contains BRG1 or BRM as an ATPase subunit, but the physiological relevance of these ATPases is not yet clear. Here, we studied the developmental regulation of the brm gene. A differentiation-specific up-regulation of BRM expression was observed with P19, F9 and C2C12 cells as with neural cells and hepatocytes. The promoter region of brm contains two putative binding sites for CCAAT enhancer binding protein beta (C/EBPbeta). Each site partially overlapped with binding sites for GATAs. C/EBPbeta stimulated the transcriptional activity of the brm promoter but GATA2 and 3 down-regulated the expression. C/EBPbeta bound to the proximal sequences of the promoter in differentiated cells and was replaced by GATAs which bound to the overlapping sites in the undifferentiated state. C/EBPbeta and GATAs may developmentally regulate the expression of brm by mutually exclusive binding.