NCBI Summary:
The protein encoded by this gene shares similarity with BRE1 of S. cerevisiae. The protein encoded by this human gene is an E3 ubiquitin ligase that regulates chromosome structure by monoubiquitinating histone H2B. This protein acts as a putative tumor suppressor and positively regulates the p53 tumor suppressor as well as numerous histone H2A and H2B genes. In contrast, this protein also suppresses the expression of several protooncogenes and growth-related genes, including many genes that are induced by epidermal growth factor. This gene selectively suppresses the expression of some genes by interfering with chromatin recruitment of transcription elongation factor SII (TFIIS). [provided by RefSeq, Feb 2012]
General function
Chromosome organization, Enzyme
Comment
Cellular localization
Nuclear
Comment
Ovarian function
Germ cell development
Comment
dBre1/dSet1-dependent pathway for histone H3K4 trimethylation has essential roles in controlling the germline stem cell maintenance and germ cell differentiation in the Drosophila ovary. Xuan T et al. The Drosophila ovarian germline stem cells (GSCs) constantly experience self-renewal and differentiation, ensuring the female fertility throughout life. The balance between GSC self-renewal and differentiation is exquisitely regulated by the stem cell niche, the stem cells themselves and systemic factors. Increasing evidence has shown that the GSC regulation also involves epigenetic mechanisms including chromatin remodeling and histone modification. Here, we find that dBre1, an E3 ubiquitin ligase, functions in controlling GSC self-renewal and germ cell differentiation via distinct mechanisms. Removal or knock down of dBre1 function in the germline or somatic niche cell lineage leads to a gradual GSC loss and disruption of H3K4 trimethylation in the Drosophila ovary. Further studies suggest that the defective GSC maintenance is attributable to compromised BMP signaling emitted from the stem cell niche and impaired adhesion of GSCs to their niche. On the other hand, dBre1-RNAi expression in escort cells causes a loss of H3K4 trimethylation and accumulation of spectrosome-containing single germ cells in the germarium. Reducing dpp or dally levels suppresses the germ cell differentiation defects, indicating that dBre1 limits BMP signaling activities for the differentiation control. Strikingly, all phenotypes observed in dBre1 mutant ovaries can be mimicked by RNAi-based reduced expression of dSet1, a Drosophila H3K4 trimethylase. Moreover, genetic studies favor that dBre1 interacts with dSet1 in controlling GSC maintenance and germ cell differentiation. Taken together, we identify a dBre1/dSet1-dependent pathway for the H3K4 methylation involved in the cell fate regulation in the Drosophila ovary.