Dynamic modulation of Polycomb-mediated epigenetic states in Drosophila development and regeneration
Final Report Abstract
Dynamic changes in epigenetic states are associated with the intriguing process of reprogramming during tissue regeneration or lead to disease states, such as cancer. To shed light on these little understood processes, I proposed to establish an Emmy Noether group to specifically investigate how the Polycomb group of epigenetic silencers targets genes to support remodelling and proliferation of damaged tissue or tumors. Over the period of my Emmy Noether Funding, I have achieved the majority of milestones as laid out in my Emmy Noether Grant Proposal. While we have not been able to demonstrate that PcG specifically target a tissue remodeling program during wound healing (Aim 1), we identified a novel tumor suppression mechanism specific to epithelial tissues, which also acts on PcG mutant cells when they arise in tissues. In addition, we described the previously unknown ability of imaginal disc to organize long-range oscillatory Calcium waves. Establishing an inducible, cell-type specific DamID system allowed us, however, to demonstrate that upregulation of oncogenic genes in the tumor scrib tumor model correlates with loss of PcG binding and regulation by stress-induced transcription factors, such as AP-1, ATF3 and Cnc (Aim2). We furthermore established a tissue regeneration model in wing imaginal discs in the lab and used it to dissect the epigenetic regulation of tissue damage responses and ultimately characterized the genetic requirements for cell survival in regenerating domains. This work also provided a detailed understanding of the role of JNK and JAK/STAT in cellular responses to tissue stress (Aim3). Finally, we created a cell culture model to better analyze epigenetic adaptations to cellular stress. While this model proved to be less useful in dissecting epigenetic regulation of proliferation genes, such as upd1-3, it allowed us to generate a deep phospho-proteome of chromatin-interacting proteins during oxidative stress and thus an understanding of the phosphorylation events that may occur in PcG/TrxG complexes in response to tissue stress (Aim 4). Importantly, we still benefit from the firm technical foundation laid during the Emmy Noether funding period, where we established imaginal disc regeneration models based on genetic cell ablation and surgical injury, imaginal disc tumor models based on oncogene and tumor suppressor gene manipulation, oxidative stress model in tissue culture, inducible cell-type specific DamID methodology, next generation sequencing library preparation and bioinformatics analysis, extensive imaging expertise (Confocal, Spinning discs, 2-photon, FLIM) and image segmentation and quantification workflows in Fiji. Combined, the work ultimately answered many of the questions I had raised and has opened up multiple avenues of research that now support the diverse project tracks in the lab.
Publications
- The transcriptional response to tumorigenic polarity loss in Drosophila Elife. 2015
Bunker BD, Nellimoottil TT, Classen AK and Bilder D
(See online at https://doi.org/10.7554/eLife.03189) - Interface contractility between differently fated cells drives cell elimination and cyst formation Current Biology. 2016. 26(5):563-74
Bielmeier C, Alt S, Weichselberger V, La Fortezza M, Harz H, Jülicher F, Salbreux G, Classen AK
(See online at https://doi.org/10.1016/j.cub.2015.12.063) - JAK/STAT signalling mediates cell survival in response to tissue stress Development. 2016. 143(16):2907-19
La Fortezza M, Schenk M, Cosolo A, Kolybaba A, Grass I, Classen AK
(See online at https://doi.org/10.1242/dev.132340) - Calcium spikes, waves and oscillations in a large, patterned epithelial tissue Scientific Reports. 2017. 7:42786
Balaji R, Bielmeier C, Harz H, Bates J, Stadler C, Hildebrand A, Classen AK
(See online at https://doi.org/10.1038/srep42786) - Ubiquitylation of the acetyltransferase MOF in Drosophila melanogaster PLOS One. 2017.12(5):e0177408
Schunter S, Villa R, Classen AK, Beli P, Becker P
(See online at https://doi.org/10.1371/journal.pone.0177408) - DamID-profiling of dynamic Polycomb-binding sites in Drosophila imaginal disc development and tumorigenesis Epigenetics and Chromatin. 2018. 11(1):38
La Fortezza M, Grigolon G, Cosolo A, Pinduyrin A, Breimann L, van Steensel B, Classen AK
(See online at https://doi.org/10.1186/s13072-018-0206-0) - JNK-dependent cell cycle stalling in G2 promotes survival and senescence-like phenotypes in tissue stress Elife. 2019. pii: e41036
Cosolo A, Jaiswal J, Csordás G, Grass I, Uhlirova M, Classen AK
(See online at https://doi.org/10.7554/eLife.41036.001)
