Project description:Microarray analysis of gene expression profiles in control and M1BP-depleted Drosophila S2R+ cells. The results of this analyses are reported in Li, J. and D.S. Gilmour (2013) The newly identified transcription factor M1BP ad GAGA factor orchestrate distinct mechanisms of transcriptional regulation on paused genes. The EMBO J, in press. Four biological replicates comparing total RNA isolated from M1BP-RNAi treated and LacZ-RNAi treated cells.
Project description:Microarray analysis of gene expression profiles in control and M1BP-depleted Drosophila S2R+ cells. The results of this analyses are reported in Li, J. and D.S. Gilmour (2013) The newly identified transcription factor M1BP ad GAGA factor orchestrate distinct mechanisms of transcriptional regulation on paused genes. The EMBO J, in press.
Project description:We sought to determine the genomic binding profile of the Drosophila Hox protein AbdA in a homogenous cell system. S2-DRSC cells that have no Hox expression were stably transfected with HA-tagged AbdA under the control of a metallothionein promoter. Upon AbdA expression, we identified high enrichment of AbdA at a large number transcription start sites that colocalises with the GAGA and M1BP. Genes targeted by GAGA and M1BP contain paused RNA polymerase II and show enrichment of PcG proteins. Upon AbdA binding at M1BP-target sites, a significant reduction in PcG protein binding is observed with a concomitant reduction in RNA Pol II pausing. These data suggest that AbdA targets both GAGA- and M1BP-controlled genes, and at M1BP-controlled genes, AbdA binding is sufficient to release PcG-mediated RNA Pol II pausing to induce gene transcription.
Project description:The genomic distribution of a novel transcription factor called M1BP was determined in Drosophila S2R+ cells Polyclonal antibody raised against M1BP was used to immunoprecipitate M1BP-DNA adducts generated by treating Drosophila cells with formaldehyde, lysing the cells, and shearing DNA by sonication. Immunoprecipitated DNA was sequenced using the AB SOLiD system.
Project description:Promoter-proximal pausing of RNA polymerase II (Pol II) is a widespread in higher eukaryotes. Previous studies have shown that GAF is enriched at paused genes, but the role of GAF in pausing has not been well characterized on a genome-wide level. To investigate the role of GAF in pausing, we RNAi-depleted GAF from Drosophila S2 cells, and examined the effects on promoter-proximal polymerase. We confirmed the importance of GAF for pausing on the classic pause model gene Hsp70. To determine the dependence of pausing on GAF genome-wide, we assayed the levels of transcriptionally-engaged polymerase genome-wide using GRO-seq in control and GAF-RNAi cells. We found that promoter-proximal polymerase was significantly reduced on a subset of paused genes with GAF-bound promoters. There is a dramatic change in nucleosome distribution at genes with reduction in pausing upon GAF depletion and intergenic GAF binding sites in GAF knock-down, suggesting that GAF allows the establishment of pausing at these genes by directing nucleosome displacement off of the promoter. In addition, the insulator factor BEAF, BEAF-interacting protein Chriz, and transcription M1BP enrichment on unaffected genes suggests that redundant transcription factors or insulators protect other GAF-bound paused genes from GAF knock-down effects. Three biological replicates of MNase digested chromatin from LacZ-RNAi and GAGA factor-RNAi cells.
Project description:Chromatin insulators are DNA-protein complexes that establish distinct higher order transcriptional domains. In Drosophila, CP190 is the only common factor for all the DNA-binding insulator protein complex. Insulators harbour two properties: they can block communication between an enhancer and a promoter, and also act as a barrier between heterochromatin and euchromatin. In Drosophila, the gypsy insulator complex contains three core components; Su(Hw), CP190 and Mod(mdg4)67.2. In our studies, using mass-spec analysis and of immunopurified complexes from Drosophila embryonic nuclear extracts, we identified the transcription factor Motif 1 Binding Protein (M1BP) associated with CP190 and verified this interaction by coimmunoprecipitation. Furthermore, depletion of M1BP results in loss of both enhancer-blocking and barrier activities, also disrupts the nuclear localization of CP190-marked insulator bodies within the developing fly. ChIP-seq analysis of both factors in Kc167 cultured hemocytes revealed extensive overlap of the two factors, particularly at Motif 1 containing promoters. Depletion of M1BP results in extensive loss of CP190 chromatin association, and depletion of CP190 also greatly affects M1BP chromatin association. Moreover, EU-seq analysis after depletion of either CP190 or M1BP suggests they regulate gene expression in similar fashion. Further analysis using reporter assays verifies that CP190-dependent gene expression changes are dependent on the presence of Motif 1. Our results suggest a novel mechanistic relationship between CP190 and M1BP function with respect to transcriptional regulation and higher order chromatin organization.
Project description:Chromatin insulators are DNA-protein complexes that establish distinct higher order transcriptional domains. In Drosophila, CP190 is the only common factor for all the DNA-binding insulator protein complex. Insulators harbour two properties: they can block communication between an enhancer and a promoter, and also act as a barrier between heterochromatin and euchromatin. In Drosophila, the gypsy insulator complex contains three core components; Su(Hw), CP190 and Mod(mdg4)67.2. In our studies, using mass-spec analysis and of immunopurified complexes from Drosophila embryonic nuclear extracts, we identified the transcription factor Motif 1 Binding Protein (M1BP) associated with CP190 and verified this interaction by coimmunoprecipitation. Furthermore, depletion of M1BP results in loss of both enhancer-blocking and barrier activities, also disrupts the nuclear localization of CP190-marked insulator bodies within the developing fly. ChIP-seq analysis of both factors in Kc167 cultured hemocytes revealed extensive overlap of the two factors, particularly at Motif 1 containing promoters. Depletion of M1BP results in extensive loss of CP190 chromatin association, and depletion of CP190 also greatly affects M1BP chromatin association. Moreover, EU-seq analysis after depletion of either CP190 or M1BP suggests they regulate gene expression in similar fashion. Further analysis using reporter assays verifies that CP190-dependent gene expression changes are dependent on the presence of Motif 1. Our results suggest a novel mechanistic relationship between CP190 and M1BP function with respect to transcriptional regulation and higher order chromatin organization.