Figure 7.

Adult Tissue Dynamics and Signaling Pathways during Minute Competition

(A) Active cell competition between healthy and subfit cells in the Drosophila homeostatic midgut causes loss of subfit tissue. M^−/+ differentiated cells are eliminated via apoptosis and M^−/+ ISCs are lost, possibly by cell death or induction of differentiation (left). Conversely, the presence of unhealthy tissue promotes expansion of healthy stem cells and their progeny. ISCs increase their proliferation rate and their symmetric self-renewal, which fuels clonal expansion (right).

(B) M^−/+ cells drive the clonal expansion of fit cells through an inflammatory-like response. Chronic JNK signaling activation in M^−/+ cells activates constitutive expression of the JAK-STAT ligand Unpaired-3. Secreted Unpaired-3, via binding to its receptor Dome, activates JAK-STAT signaling, stimulating the proliferative expansion of wild-type clones during cell competition.