Function Dissection Of Brahma Chromatin Remodeling Complex In The Differentiation Of Drosophila Ovary Germline Stem Cell

Adult stem cells are a group of undifferentiated cells in adult tissues.They have self-renewal ability and differentiation potential.These two characteristics are important for maintaining homeostasis and repairing tissue injury.The key to the study of stem cell fate regulation is to clarify how stem cells choose to maintain self-renewal or to obtain the fate of differentiated cells.Drosophila ovary as an experimental material is easy to obtain,and the endogenous stem cells have the advantage of recognition in vivo.It is an ideal system for studying the fate regulation mechanism of stem cells in vivo.Many research evidence have suggested that epigenetic regulation plays an important role in the self-renewal and differentiation of stem cells.BRM complex is the chromatin remodeling complex of the SWI/SNF family in Drosophila,and there are two types of BRM complexes in the Drosophila,which are BAP and PBAP.These two complexes contain a common catalytic subunit-Brm.In this study,we preliminarily studied the function of the chromatin remodeling complex BRM and its important subunits in the differentiation of the ovarian reproductive stem cells of Drosophila melanogaster.We find Brm and Osa,a subunit of BAP complex play important role in GSC differentiation.(1)Down regulating the expression of brm in escort cells leads to the blocked GSC differentiation.This suggests that brm participates in the regulation of GSC differentiation in Drosophila ovary.In addition,the Polybromo,a PBAP-specific subunit,does not affect the differentiation of germline stem cells.The expression of the BAP-specific subunit Osa in the escort cells cause the differentiation defect of the germline stem cells.It is reasoned that the BRM chromatin remodeling complex may work as a BAP complex in the GSC differentiation and development of female Drosophila melanogaster.(2)BMP signal activation molecular markers pMad and Dad-lacZ detection results show that the down regulation of osa or brm expression in the escort cells results in excessive activation of BMP signal in the germarium,suggesting that brm and osa regulating GSC differentiation process may depend on the BMP signaling pathway.Further studies show that the expression pattern of differentiation factor Bam is changed in the germarium where brm or osa expression is down-regulated,suggesting that brm and osa mediated regulation of germ cell differentiation may be achieved through Bam molecular pathway.(3)The down-regulation of brm or osa in the escort cells results in the changes in the morphology of the escort cells,and the differentiation germ cells can not be extended.It is suggested that the maintenance of EC morphology may be the basis of brm and osa to regulate the differentiation of GSC.The above results indicate that the Brm and Osa of BRM chromatin remodeling complex participate in the regulation of GSC differentiation and development through specific mechanisms.This study will provide more clues for exploring the regulation mechanism of stem cell self-renewal and differentiation.