Functional Analysis Of SWI/SNF Chromatin Remodeling Complex In Human Embryonic Stem Cell

ATP-dependent chromatin remodeling complexes are a notable group of epigenetic modifiers that use the energy of ATP hydrolysis to change the structure of chromatin, thereby altering its accessibility to nuclear factors. BRG1or BRM is the core subunit of SWI/SNF and has the activity of ATPase.Mammalian SWI/SNF ATP-dependent chromatin remodeling complexes are essential for formation of the totipotent and pluripotent cells of the early embryo. Recently years, the association between ATP-dependent chromatin remodeling complexes and embryonic stem cells has been researched broadly, but it was explored little in human embryonic stem cells (ES). Microarray assays revealed that the decrease of BRG1induced by RNA interference with siRNA, leads to difference between gene exprression patterns of human and mouse ES in a large extent. The results from Wetstern Blot and Q-RT-PCR suggested that BRG1is dominant in SWI/SNF complex of hunman ES. Therefore, to research the impact of SWI/SNF complex on human embryonic stem cells’ self-renewal and pluripotency, we induced persistently low expression level of BRG1with shRNA, and found that the human ES colonies displayed significant differentiated morphology after7-10days of BRG1knockdown. FACS and AP staining also revealed that human ES were indeed differentiated because of continued BRG1’s decrease. At the same time, the Q-RT-PCR results revealed that Brgl knockdown could lead to the human ES differentiate to three germ-layers’ and trophectodermal derivatives in different extent. Chip data reveal that BRG1occupied Oct4, However, Oct4and Nanog, the pluripotency relative genes don’t have significant changes in the gene expression level at the beginning of BRG1knockdown. In addition, Microarray, Q-RT-PCR and Chip assay all indicated that BRG1affected the expression of cell cycle regulators, but we haven’t gotten the evidence that BRG1can significantly affect the cell cycle of human ES. Our further study will focus on the model of cell cycle arrest and DNA damage repair to research the regulation of BRG1on cell cycle. All together, the SWI/SNF complex is essential for the maintainence of self-renewal and pluripotency, and affects widely the cell cycle and growth of of human ES.