Project description:This project’s aim was to compare the transcriptional profiles of olfactory sensory neurons in Drosophila melanogaster in order to identify novel genes that specify neuron-specific functions/phenotypes or may otherwise be involved in the development of the olfactory system. The isolation of sufficient numbers of intact olfactory sensory neurons (OSN) from the antenna of Drosophila melanogaster has so far limited single-cell transcriptomic approaches being applied to the adult fly antenna. Targeted DamID (TaDa) provides an alternative approach for profiling transcriptional activity in a cell-specific manor that bypasses the need for isolating OSN. Using the Gal4/UAS system, we applied TaDa to seven OSN populations and compared differences in Pol II occupancy for genes across these datasets.
Project description:Targeted DamID (TaDa) measures gene expression using a DNA adenine methyltransferase (Dam) fused to RNA polymerase II (Dam Pol II) to methylate DNA as the genome is transcribed (Southall, Gold et al. 2013, PMID: 23792147). Here we use traditional Illumina RNA-Seq to determine if a cell’s expression profile is affected by Dam Pol II expression. Twenty-four hours prior to collection, we ubiquitously drove UAS Dam or UAS Dam Pol II using a tubulin (tub) GAL4 regulated by a temperature sensitive tub GAL80[ts] (McGuire et al. 2003, PMID: 14657498) in adult Drosophila melanogaster (taxon: 7227) whole males, whole females, testes, and ovaries.
Project description:Cell-type specific transcriptional profiling is key to understanding cell fate specification and function. In order to achieve this it has been necessary, to date, to isolate specific cell types from complex tissues. We have developed 'TaDa', a technique that enables cell-specific profiling without cell isolation. TaDa permits genome-wide profiling of DNA- or chromatin-binding proteins without cell sorting, fixation or affinity purification. The method is simple, sensitive, highly reproducible and is in principle transferable to any model system. Here we show that TaDa can be used to identify transcribed genes in a cell-type specific manner. We profile the genome-wide binding of RNA polymerase II (Pol II) in adjacent, clonally related neural stem cells in intact Drosophila brains. Our data reveal the activity of non-canonical metabolic pathways in proliferating neuroepithelial cells, and highlight a possible role for the retinal determination gene regulatory network in patterning neural stem cell fates. We also identify temporal differences in the activity of signalling pathways that control neuroepithelial cell fate by profiling Pol II occupancy at two different stages of brain development. Using RNA Pol II TaDa to profile, in a cell-type specific manner, the transcriptional state of neuroepithelial cells at two stages of larval brain development. Closely related asymmetrically dividing neural stem cells (neuroblasts) were also profiled, in order to compare the transcriptomes of two different types of neural stem cells. 3 biological relicates were performed for 3rd instar neuroepithelial cells (with one dye-swap). 2 biological relicates were performed for 3rd instar neuroblasts (with dye-swap). 2 biological relicates were performed for 1st instar neuroepithelial cells (with dye-swap). As additional supporting evidence for the Pol II TaDa technique, 2 biological relicates were performed for 3rd instar salivary glands (with dye-swap) in order to compare with previous Pol II-ChIP data for this tissue [PMID 22821985].
Project description:Targeted DamID (TaDa) is an increasingly popular method of generating cell-type specific DNA binding profiles in vivo. Although sensitive and versatile, TaDa requires the generation of new transgenic fly lines for every protein that is profiled, which is both time-consuming and costly. Here, we describe the FlyORF-TaDa system for converting an existing FlyORF library of inducible open reading frames (ORFs) to TaDa lines via a genetic cross, with recombinant progeny easily identifiable by eye colour. Profiling the binding of the H3K36me3-associated chromatin protein MRG15 in larval neural stem cells using both FlyORF-TaDa and conventional TaDa demonstrates that new lines generated using this system provide accurate and highly-reproducible DamID binding profiles. Our data further show that MRG15 binds to a subset of active chromatin domains in vivo. Courtesy of the large coverage of the FlyORF library, the FlyORF-TaDa system enables the easy creation of TaDa lines for 74% of all transcription factors and chromatin modifying proteins within the Drosophila genome.
Project description:Cell-type specific transcriptional profiling is key to understanding cell fate specification and function. In order to achieve this it has been necessary, to date, to isolate specific cell types from complex tissues. We have developed 'TaDa', a technique that enables cell-specific profiling without cell isolation. TaDa permits genome-wide profiling of DNA- or chromatin-binding proteins without cell sorting, fixation or affinity purification. The method is simple, sensitive, highly reproducible and is in principle transferable to any model system. Here we show that TaDa can be used to identify transcribed genes in a cell-type specific manner. We profile the genome-wide binding of RNA polymerase II (Pol II) in adjacent, clonally related neural stem cells in intact Drosophila brains. Our data reveal the activity of non-canonical metabolic pathways in proliferating neuroepithelial cells, and highlight a possible role for the retinal determination gene regulatory network in patterning neural stem cell fates. We also identify temporal differences in the activity of signalling pathways that control neuroepithelial cell fate by profiling Pol II occupancy at two different stages of brain development. Using RNA Pol II TaDa to profile, in a cell-type specific manner, the transcriptional state of neuroepithelial cells at two stages of larval brain development. Closely related asymmetrically dividing neural stem cells (neuroblasts) were also profiled, in order to compare the transcriptomes of two different types of neural stem cells.
Project description:The importance of the niche to provide regulatory inputs to balance stem cell self-renewal and differentiation has become clear. However, the regulatory interplay between stem cells and their niche at the whole genome level is still poorly understood. To elucidate the mechanisms controlling stem cells and their progenies as they progress through development at the transcriptional level, we recorded the regulatory program of two independent cell lineages in the Drosophila testis. We identified genes active in the soma or germline as well as genome-wide binding profiles of two transcription factors, Zfh-1 and Abd-A, expressed in somatic support cells and crucial for fate acquisition of both cell lineages. In order to uncover gene activities in the testis soma, we first determined the transcriptome of the somatic and germline lineages by RNA polymerase II Targeted DamID (TaDa) (Southall et al., 2013), followed by the identification of genes bound by two regulators active in somatic sub-populations and controlling their development using regular DNA adenine methyltransferase identification (DamID) (Van Steensel et al., 2001). For identifying abd-A and Zfh1 binding regions in the Drosophila testis the fusion protein was expressed from the uninduced minimal Hsp70 promoter of the UAS vector pUAST. As a control for nonspecific Dam activity, transgenic flies expressing the Dam alone were used (Choksi et al., 2006). To express the AbdA-Dam fusion protein, we first generated a pNDam-Myc-abdA construct by cloning abdA in the pNDam-Myc vector (van Steensel et al., 2001) and then subcloned the NDam-Myc-abdA fragment into the pUAST-attB and to express the Zfh1-Dam fusion protein, we first generated a pNDam-Myc-zfh1 construct by cloning zfh1 in the pNDam-Myc vector (van Steensel et al., 2001) and then subcloned the NDam-Myc-zfh1 fragment into the pUAST-attB. For targeted DamID (TaDa) in Drosophila 3rd instar testes cyst and germline cells. Cell-type specific DamID was performed in cyst cells (CySCs and SCCs) and early germline of 3rd instar larval testes for profiling RNA Pol II occupancy in these cells by crossing UAS-LT3-Dam-Pol II and UAS-LT3-Dam control flies to c587-GAL4 (somatic lineage) or Nanos-GAL4 (early germline) drivers. For Dam-ID two individual replicates of Dam-abd-A, Dam-Zfh1 and Dam alone have been generated whereas for TaDa, two individual replicates of c587>UAS-LT3-Dam-PolII, Nanos>UAS-LT3-Dam-Pol II and c587>UAS-LT3-Dam (control), Nanos>UAS-LT3-Dam (control) have been used. Following a methylation-sensitive DNA digestion and PCR amplification, DNA fragments from the above samples were labeled and hybridized to genomic Affymetrix arrays in duplicates (Protocol available at “www.flychip.org.uk”).
Project description:Cell-type specific transcriptional profiling is key to understanding cell fate specification, function and adaptation. This is particularly advantageous for studying specific cell types from complex tissues. In this study, we have used ‘TaDa’ (Targeted DamID), a technique that enables profiling of rare cell populations or cells difficult to isolate by conventional methods. Furthermore, TaDa profiling occurs in vivo and isn’t subject to artefacts arising from disruption of the tissues and cell sorting. Here, we profile the genome-wide binding of RNA polymerase II (Pol II) in terminal tracheal cells (TTCs) that are tightly associated with intestinal tissue from adult Drosophila. We compare terminal tracheal transcriptome from control to regenerative intestine in adult fly. Our data reveal new tracheal intrinsic mechanisms that are essential, in this gut-trachea communication, for regulating intestinal stem cell proliferative activity in context of damage. Our study represents the first analysis of terminal tracheal cell transcriptional profiling in context of homeostasis and regenerative adult intestine and provide new insight into the regulatory programs that underlie the complex interactions between gut-neighbourhood.