Metabolomics,Unknown,Transcriptomics,Genomics,Proteomics

Dataset Information

The Hox gene Abd-B controls stem cell niche function in the Drosophila testis

ABSTRACT: Stem cells reside in a specialized microenvironment, called niche, which provides essential signals controlling stem cell behavior. Proper niche architecture is a key for normal stem cell function, yet only few upstream regulators are known. Here we report that the Hox transcription factor Abd-B, active in pre-meiotic spermatocytes, affects niche positioning in the Drosophila testis by regulating integrin localization in differentiated somatic cyst cells. Loss of Abd-B results in cell non-autonomous effects within the niche including centrosome misorientation in germline stem cells (GSCs) and reduced GSC divisions in larval testis, leading to a dramatic reduction of pre-meiotic stages in adult testes. By identifying Abd-B binding regions throughout the genome, we find that Abd-B mediates its effects on niche function by directly controlling at multiple levels the localization and thus signaling activity of the Sevenless (Sev) ligand, Bride of Sevenless (Boss), via its direct targets src42A and sec63. In sum, our data show for the first time that Abd-B through local signaling provides positional cues for integrin localization, which is critical for niche localization and architecture, and ensures proper niche function and GSC activity. DamID (DNA adenine methyltransferase identification) method was used to identify direct Abd-B target genes in the Drosophila 3rd instar larval testis Dam was fused to the N terminus of Abd-B and transgenic flies were generated. For identifying Abd-B targets in the Drosophila testis the fusion protein was expressed from the uninduced minimal Hsp70 promoter of the UAS vector pUAST (Brand and Perrimon, 1993). As a control for nonspecific Dam activity, transgenic flies expressing the Dam alone were used (Choksi et al., 2006). Subsequently, genomic DNA was extracted from 3rd instar larval testes, expressing either the Dam-Abd-B fusion protein or the Dam protein alone using a specific protocol (Tolhuis et al., 2011); and van Steensel personal communication). Two individual replicates, for Dam-AbdB and Dam alone, have been generated. Following a methylation-sensitive DNA digestion and PCR amplification, DNA fragments from Dam-Abd-B and control DNA were labeled and hybridized to genomic Affymetrix arrays in duplicates (Protocol available at M-bM-^@M-^\www.flychip.org.ukM-bM-^@M-^]).

ORGANISM(S): Drosophila melanogaster

SUBMITTER: nati ha

PROVIDER: E-GEOD-53709 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

ACCESS DATA

Similar Datasets

Project description:Salivary gland polytene chromosomes of Drosophila melanogaster have a reproducible set of intercalary heterochromatin sites, characterized by late DNA replication, underreplicated DNA, breaks and frequent ectopic contacts. The SuUR mutation has been shown to suppress underreplication, and wild-type SUUR protein is found at late-replicating intercalary heterochromatin sites and in pericentric heterochromatin. We performed a genome-wide mapping of SUUR target genes in the non-polytenic Drosophila Kc cells by using DamID. This approach is based on the ability of a chromatin protein fused to Escherichia coli DNA adenine methyltransferase (Dam) to methylate the native binding site of the chromatin protein. Dam-fusion proteins are expressed at very low levels to avoid mistargeting. Subsequently, methylated DNA fragments are isolated, labeled (using Cy3 or Cy5) and hybridized to a microarray. Methylated DNA fragments from cells transfected with Dam alone served as reference. Genomic binding sites of the protein can then be identified based on the targeted methylation pattern. For detailed background information on DamID, see: van Steensel, B., Delrow, J. & Henikoff, S. Chromatin profiling using targeted DNA adenine methyltransferase. Nat Genet 27, 304-8 (2001); van Steensel, B. & Henikoff, S. Identification of in vivo DNA targets of chromatin proteins using tethered dam methyltransferase. Nat Biotechnol 18, 424-8 (2000). We generated both an N- and a C-terminal fusion of the full-length SuUR open reading frame with Dam (Dam-SUUR and SUUR-Dam, respectively). For each SUUR fusion protein we performed four independent replicates. We used for this study a cDNA array developed by the GeneCore facility in EMBL (Heidelberg, Germany), covering the DGC1 and DGC2 cDNA libraries from the Berkeley Drosophila Genome Project, which represents more than 70% of the coding Drosophila genome. We found that SUUR preferentially binds to genes that are transcriptionally silent and late replicated. We compared the SUUR binding profile to the binding profile of three PcG proteins, which are known to bind to many intercalary heterochromatin sites, and found that there is a significant overlap with Pc and esc, but less with Sce. A significant overlap is also detected with two markers of pericentric heterochromatin, the heterochromatin proteins HP1 and SU(VAR)3-9. Finally, we demonstrated that SUUR binding profile negatively correlates with DNA polytenization level in salivary gland polytene chromosomes. Taken together, these results suggest that SUUR modulates the level of underreplication by direct binding to intercalary and pericentric heterochromatin.

Project description:Protein phosphatase 1 (PP1) is a Ser/Thr phosphatase that has been implicated in many key cellular functions including transcriptional regulation. Due to its involvement these many processes, it becomes difficult to directly link PP1 to transcriptional regulation on the chromatin level as no direct genomic binding sites have been identified. Previous work has failed to address this as the most common method used, namely chromatin immunoprecipitation (ChIP), is an antibody-dependent technique and currently no ChIP-grade PP1 antibodies have been developed. Using DamID, an alternative to ChIP, we have identified PP1 isoform-specific binding sites on the promoter regions of genes. We also identified the binding sites of three main PP1 regulatory subunits (R-subunits) in order to identify potential PP1 holo-enzymes binding sites. Our study revealed the full extent of PP1 isoform specific binding an allowed us to investigate the dependency of the R-subunits on PP1 for chromatin targeting. This data establishes PP1 as a chromatin interactor and allow for the identification of direct effects PP1 can have on the regulation of the genes on whose promoter it is bound. HeLa stable cell lines were created using constructs derived from pIND-(V5)-EcoDam. These constructs express trace amounts of Dam or C-terminal fusions with PP1α, PP1β, PP1γ and three R-subunits, PNUTS, NIPP1 and RepoMan, both wildtype (WT) and their PP1-binding mutants (RATA). Two independent stable cell lines were set up for each of the constructs. DamID-DNA was labeled and hybridized to a GeneChip Human Promoter 1.0R Array (Affymetrix, Santa Clara, CA, USA). The tiling array readouts were analyzed with the “model-based analysis of tiling arrays” (MAT) algorithm (version 1.0.0) against the hg19 reference genome. We normalized two biological replicates of each Dam-fusion over two Dam-only biological replicates. Each biological repeat consisted of 2 technical repeats pooled together prior to hybridization to the tiling array.

Dataset Information

The Hox gene Abd-B controls stem cell niche function in the Drosophila testis

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure