A Chromatin Remodeling Factor, BRM has Important Roles in Cell Differentiation

Abstract

The modification of chromatin structure is increasingly recognized to be an important factor for transcriptional regulation. So far, it is known that the state of chromatin compaction is controlled by two major mechanisms. One is a histone acetyltransferase and deacetylase system and the other is a regulatory system containing chromatin remodeling complexes (2). The former enzymes acetylate or deacetylate N-terminal tail structures of histones and control chromatin opening and compaction. The chromatin remodeling complex was characterized first in Saccharomyces cerevisiae as a multi-protein complex which controls mating type switch (SWI) and sucrose non-fermenting (SNF) genes. ATP-dependent chromatin remodeling activity of the complex was recently identified (3). This SWI/SNF complex has an ATPase subunit called SWI2/SNF2, and its activity is essential for chromatin remodeling (3). The homologs of SWI2/SNF2 have been identified in higher eukaryotes, and they also form multi-protein complexes of chromatin remodeling factors (1). Mammalian SWI/SNF complexes are composed of more than 8 subunits. Until now, two ATPase subunits have been identified and named BRM and BRG1 (4, 5). The SWI/SNF complex containing either BRG1 or BRM shows chromatin remodeling activity, and activates or inactivates gene expression. In this article, we analyzed BRM and BRG1 expression during neural differentiation of NPCs and P19 embryonal carcinoma cells and liver differentiation to study its role in neural differentiation.