Cell Competition Modifies Adult Stem Cell and Tissue Population Dynamics in a JAK-STAT-Dependent Manner.
Bottom Line: Throughout their lifetime, cells may suffer insults that reduce their fitness and disrupt their function, and it is unclear how these potentially harmful cells are managed in adult tissues.We address this question using the adult Drosophila posterior midgut as a model of homeostatic tissue and ribosomal Minute mutations to reduce fitness in groups of cells.Finally, we show that winner cell proliferation is fueled by the JAK-STAT ligand Unpaired-3, produced by Minute(-/+) cells in response to chronic JNK stress signaling.
Affiliation: The Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.Show MeSH
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Mentions: We next considered whether, in turn, normal cells could be affected by the presence of suboptimal cells and what impact this might have on their tissue-colonization potential. Although the clonal competition assay (Figure 2C) shows that wild-type cells have a clonal advantage over M−/+ cells, this might result solely from their intrinsically faster proliferation rate, a phenomenon known as biased competition (Snippert et al., 2014). Indeed, wild-type ISCs divide significantly faster than M−/+ ISCs in this tissue (Figures S2A–S2C), and cell-autonomous differences in proliferation rate have been proposed to account entirely for the clonal expansion of wild-type clones during Minute competition in wing imaginal discs (Martín et al., 2009). To address this, we compared the behavior of control wild-type clones surrounded by wild-type cells to that of wild-type clones surrounded by M−/+ cells by lineage tracing (Figures 3A–3C) at different time points. Because in both setups the genotype of wild-type cells was identical, any change we observed between the two conditions would have to be a consequence of the interaction with M−/+ cells. Interestingly, wild-type stem cells grew into bigger clones when surrounded by M−/+ cells (Figure 3C). This was observed at early (3-day) and especially at late (20-day) time points ACI. Importantly, increased clone expansion was not a general feature of cells in M−/+ guts, because control M−/+ ISCs formed smaller clones in M−/+ guts (Figures S2D–S2F), consistent with their reduced proliferation rate (Figures S2A–S2C). Furthermore, whereas control clones grew in a manner consistent with homeostatic behavior (i.e., the average number of labeled progeny tended to plateau after initial growth, consistent with proliferation balanced by loss; de Navascués et al., 2012), competing wild-type clones expanded nonhomeostatically (Figure 3D).
Affiliation: The Wellcome Trust/Cancer Research UK Gurdon Institute, University of Cambridge, Tennis Court Road, Cambridge CB2 1QN, UK.