1. Wnt6 maintains anterior escort cells to promote GSC survival.
Wnt6 maintains anterior escort cells to promote GSC survival. (A) C587Gal4 expression of the cell-cycle indicator FUCCI identified two distinct cell populations: the anterior region contained exclusively E2F1-EGFP-positive green cells that are quiescent in G1 phase, whereas the posterior regions contained cycling cells expressing CycB-nls-mRFP (red in S phase, or yellow in M/G2 phases). (B) Wnt6 RNAi significantly reduced the number of both cell populations. (C) Quantification of E2F1-EGFP-positive and CycB-nls-mRFP-positive escort cells as shown in A,B. ***P<0.001 (Student's t-test). Error bars represent s.e.m. (D) Model for how cap cells organize the germline stem cell niche in the fly germarium. Cap cells secrete Wnt6 ligands that act on abutting anterior escort cells to activate Wnt signaling, which is essential for their survival. Anterior escort cells function as an integral component of the GSC niche by promoting BMP signaling in GSCs and DE-cadherin-mediated anchorage of GSCs within the niche.
Xiaoxi Wang, and Andrea Page-McCaw Development 2018;145:dev158527
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