Project description:The systemic response to injury in Drosophila melanogaster is characterized by the activation of specific signaling pathways that facilitate the regeneration of wounded tissue and help coordinate wound healing with organism growth. The mechanisms by which damaged tissues influence the development and function of peripheral non-injured tissues is not fully understood. Injury was induced in early third instar larvae via temperature-dependent cell death in wing imaginal discs. Microarray analysis using RNA isolated from injured and control was used to identify genes underlying the systemic injury response. We identified 150 genes which were differentially expressed in response to localized cell death in wing imaginal discs. Upregulated genes were associated biological processes including carnitine biosynthesis, signal transduction and regulation of oxidoreductase activity while terms associated with downregulated genes included wound healing, imaginal disc-derived wing hair outgrowth, and regulation of glutamatergic synaptic transmission. Pathway analysis revealed that wing disc damage led to changes in fatty acid, cysteine, and carnitine metabolism. One gene, 14-3-3ζ, which encodes a known regulator of Ras/MAPK signaling was identified as a potential regulator of transdetermination during tissue regeneration. Our results raise the possibility that immune function and cell proliferation during wing disc repair and regeneration in Drosophila may require the sulfur amino acid cysteine and its’ metabolites, taurine and glutathione, similar to what has been reported during tissue repair in mammals. Further, it seems likely that imaginal disc damage stimulates the mobilization of fatty acids to support the energetically demanding process of tissue regeneration. The roles of additional genes that are differentially regulated following imaginal disc injury remain to be elucidated.
Project description:We have carried out eukaryotic whole-genome Illumina RNA-seq of regenerating blastema cells and control undamaged wing imaginal disc cells to identify the differentially expressed genes during regeneration.
Project description:Cohesin is crucial for proper chromosome segregation, but also regulates gene transcription and organism development by poorly understood mechanisms. We find that in Drosophila, cohesin functionally interacts with Polycomb group (PcG) silencing proteins at both silenced and active genes. Cohesin unexpectedly facilitates binding of Polycomb Repressive Complex 1 (PRC1) to many active genes. In contrast, cohesin and PRC1 binding are mutually antagonistic at silenced genes. PRC1 depletion decreases phosphorylated RNA polymerase and mRNA at many active genes, but increases them at silenced genes. Cohesin also facilitates long-range interactions between Polycomb Response Elements in the invected-engrailed gene complex where it represses transcription. These multiple distinct cohesin-PcG interactions reveal a previously unrecognized role for PRC1 in facilitating productive gene transcription, and provide new insights into how cohesin and PRC1 control development. ChIP-chip of cohesin, Polycomb group proteins, and RNA Polymerase II was performed in whole wing imaginal discs in developing wing imaginal disc, revealing that cohesin and Polycomb Repressive Complex 1 (PRC1) components co-bind with cohesin proteins at active genes. We then measured cohesin, Pc, and H3K27me3 separately in anterior and posterior wing imaginal discs and compared their binding at the invected-engrailed complex, which is silenced in the anterior disc, and expressed in its posterior. This confirmed that cohesin and PRC1 (Pc) co-bind at inv-en in its active state, and H3K27me3 and PRC1 (Pc) co-target inv-en in its silenced state. Comparison of binding between Pc-RJ and Pc-VP was performed, and revealed that Pc-VP is subject to epitope masking specifically at active genes. Finally, we measured cohesin and Pc binding in Drosophila ML-DmBG3-c2 cells, and found that they co-bind active genes in this cell line in as well as in wing imaginal discs. ChIP-chip of cohesin subunit Rad21 after PRC1 component Ph depletion, and ChIP-chip of PRC1 subunit Pc after Rad21 RNAi depletion, revealed that these two complexes affect one another's binding. Finally, ChIP-chip of Rpb3 (representing total Pol II) and Ser2P-Pol II (representing elongating Pol II) after PRC1 component Ph depletion revealed that PRC1 restrains entry of non-phosphorylated Pol II into gene bodies.
Project description:Regeneration of fragmented Drosophila imaginal discs occurs in an epimorphic manner, involving local cell proliferation at the wound site. Following disc fragmentation, cells at the wound site activate a restoration program through wound healing, regenerative cell proliferation and repatterning of the tissue. However, the interplay of signaling cascades, driving these early reprogramming steps, is not well understood. Here we profiled the transcriptome of regenerating cells in the early phase within twenty-four hours after wounding. We found that JAK/STAT signaling becomes activated at the wound site and promotes regenerative cell proliferation in cooperation with Wingless (Wg) signaling. In addition, we demonstrated that the expression of Drosophila insulin-like peptide 8 (dilp8), which encodes a paracrine peptide to delay the onset of pupariation, is controlled by JAK/STAT signaling in early regenerating discs. Our findings suggest that JAK/STAT signaling plays a pivotal role in coordinating regenerative disc growth with organismal developmental timing. In order to analyze transcriptome change in early regenerating imaginal disc, Drosophila prothorasic leg discs were fragmented (to anterior one-quarter or posterior three-quarters) and cultured ex vivo in adult fly abdomen. Regenerating cells in early regeneration phase (at 12 or 24 hours after wounding) were subjected to transcriptome profiling with Affymetrix microarrays. For control samples, the corresponding regions of uncut-cultured discs and uncut-uncultured discs were used.
Project description:Drosophila imaginal disc cells exhibit a remarkable ability to switch cell fates under various perturbations, a phenomenon known as transdetermination (TD). The winged eye (wge) gene induces eye-to-wing TD by its overexpression in eye imaginal discs using eye specific Gal4 driver (eyeless-Gal4). Gene network controlling this process, however, is largely unclear. Additionally, we identified that heterochromatin-related histone methyltransferase Su(var)3-9 is essential for wge-mediated TD. We used microarray to detail the global gene network underlying wge-mediated eye-to-wing TD, and the involvement of Su(var)3-9 in the gene network.
Project description:Comparisons between whole animal and epidermis with attached muscle, salivary gland, wing disc, midgut, and central nervous system tissues at approximately 18 hours before pupariation. Keywords = Drosophila, ecdysone, network, genomic, microarray, organogenesis, EcR, midgut, central nervous system, salivary gland, epidermis, imaginal disc, development Keywords: other