Project description:Neuroendocrine (NE) cells use large dense core vesicles (LDCVs) to traffic, process, store and secrete neuropeptide hormones through the regulated secretory pathway. The DIMM basic helix-loop-helix transcription factor of Drosophila controls the level of regulated secretory activity in NE cells. To pursue its mechanisms, we have performed two independent genome-wide analyses of DIMMM-bM-^@M-^Ys activities: (i) in vivo chromatin immunoprecipitation (ChIP) to define genomic sites of DIMM occupancy and (ii) deep sequencing of purified DIMM neurons to characterize their transcriptional profile. By this combined approach, we showed that DIMM binds to conserved E-boxes in enhancers of 212 genes whose expression is enriched in DIMM-expressing NE cells. DIMM binds preferentially to certain E-boxes within first introns of specific gene isoforms. Statistical machine learning revealed that flanking regions of putative DIMM binding sites contribute to its DNA binding specificity. DIMMM-bM-^@M-^Ys transcriptional repertoire features at least 20 LDCV constituents. In addition, DIMM notably targets the pro-secretory transcription factor, CREB-A, but significantly, DIMM does not target any neuropeptide genes. DIMM therefore prescribes the scale of secretory activity in NE neurons, by a systematic control of the regulated secretory pathway at steps that are both proximal and distal. DIMM::MYC ChIP-chip (c929>DIMM::MYC/tubGAL80ts) and control (c929>tubGAL80ts): 2 replicates each, input and IP samples. Total of 8 arrays
Project description:Neuroendocrine (NE) cells use large dense core vesicles (LDCVs) to traffic, process, store and secrete neuropeptide hormones through the regulated secretory pathway. The DIMM basic helix-loop-helix transcription factor of Drosophila controls the level of regulated secretory activity in NE cells. To pursue its mechanisms, we have performed two independent genome-wide analyses of DIMM’s activities: (i) in vivo chromatin immunoprecipitation (ChIP) to define genomic sites of DIMM occupancy and (ii) deep sequencing of purified DIMM neurons to characterize their transcriptional profile. By this combined approach, we showed that DIMM binds to conserved E-boxes in enhancers of 212 genes whose expression is enriched in DIMM-expressing NE cells. DIMM binds preferentially to certain E-boxes within first introns of specific gene isoforms. Statistical machine learning revealed that flanking regions of putative DIMM binding sites contribute to its DNA binding specificity. DIMM’s transcriptional repertoire features at least 20 LDCV constituents. In addition, DIMM notably targets the pro-secretory transcription factor, CREB-A, but significantly, DIMM does not target any neuropeptide genes. DIMM therefore prescribes the scale of secretory activity in NE neurons, by a systematic control of the regulated secretory pathway at steps that are both proximal and distal.
Project description:FoxA transcription factors play major roles in organ-specific gene expression. How FoxA proteins achieve specificity is unclear, given their broad expression patterns and requirements in multiple cell types. Here, we characterize Sage, a basic helix-loop-helix (bHLH) transcription factor expressed exclusively in the Drosophila salivary gland (SG). We identify Sage targets and show that not only are both Sage and the single Drosophila FoxA protein, Fork head (Fkh), required for expression of these genes, but coexpression of Sage and Fkh is sufficient to drive target gene expression in multiple other cell types. Sage and Fkh drive expression of the bZip transcription factor Senseless (Sens), which boosts expression of Sage/Fkh targets. Importantly, Sage, Fkh and Sens colocalize on salivary gland polytene chromosomes. Thus, Fkh drives cell-type specific gene expression as part of a tissue-specific transcription module that includes Sage and Sens, providing a new paradigm for how mammalian FoxA proteins acheive specificity.
Project description:A cascade of basic helix-loop-helix transcription factors guide tapetal cell development in maize anthers, using proteins conserved in Arabidopsis and rice but deployed with a distinctive timing. Anthers were dissected and staged to be 1500 μm in length (+/- 100 μm) and samples were compared between mutants and fertile siblings on an Agilent 4x44 custom microarray. Analysis included MS32 which is another basic helix-loop-helix factor that acts later during tapetal differentiation.
Project description:FoxA transcription factors play major roles in organ-specific gene expression. How FoxA proteins achieve specificity is unclear, given their broad expression patterns and requirements in multiple cell types. Here, we characterize Sage, a basic helix-loop-helix (bHLH) transcription factor expressed exclusively in the Drosophila salivary gland (SG). We identify Sage targets and show that not only are both Sage and the single Drosophila FoxA protein, Fork head (Fkh), required for expression of these genes, but coexpression of Sage and Fkh is sufficient to drive target gene expression in multiple other cell types. Sage and Fkh drive expression of the bZip transcription factor Senseless (Sens), which boosts expression of Sage/Fkh targets. Importantly, Sage, Fkh and Sens colocalize on salivary gland polytene chromosomes. Thus, Fkh drives cell-type specific gene expression as part of a tissue-specific transcription module that includes Sage and Sens, providing a new paradigm for how mammalian FoxA proteins acheive specificity. Three wild type (reference) samples were obtained from the Oregon R strain, age matched and treated the same as the three experimental samples isolated from Stages 11-16 embryos expressing UAS-Sage controlled by the tub-Gal4 driver.
Project description:FoxA transcription factors play major roles in organ-specific gene expression. How FoxA proteins achieve specificity is unclear, given their broad expression patterns and requirements in multiple cell types. Here, we characterize Sage, a basic helix-loop-helix (bHLH) transcription factor expressed exclusively in the Drosophila salivary gland (SG). We identify Sage targets and show that not only are both Sage and the single Drosophila FoxA protein, Fork head (Fkh), required for expression of these genes, but coexpression of Sage and Fkh is sufficient to drive target gene expression in multiple other cell types. Sage and Fkh drive expression of the bZip transcription factor Senseless (Sens), which boosts expression of Sage/Fkh targets. Importantly, Sage, Fkh and Sens colocalize on salivary gland polytene chromosomes. Thus, Fkh drives cell-type specific gene expression as part of a tissue-specific transcription module that includes Sage and Sens, providing a new paradigm for how mammalian FoxA proteins acheive specificity.