The Rockefeller University Press

Tissues are maintained and patterned by stem cells that are con-trolled in part by signals derived from their niches (Losick et al., 2011). Follicle stem cells (FSCs), located in the germaria of each ovariole in Drosophila melanogaster ovaries, give rise to the epi-thelium that surrounds the egg chambers (Losick et al., 2011). FSCs are regulated by several signaling pathways, including Wingless (Wg), derived from the distal (≤50 µm) terminal fila-ments (TFs) and cap niche cells (Fig. 1; Losick et al., 2011). Because this signaling is long range, an unresolved issue is how Wg molecules spread. In this issue of JCB, Wang and Page-McCaw provide new insights into this process by identifying the heparan sulfate proteoglycan (HSPG) Dally-like (Dlp) and the matrix metalloproteinase Mmp2 as positive and negative regula-tors of long-range Wg signaling in the germarium, respectively. In the Drosophila wing imaginal disc, Wg has been pro-posed to act as a morphogen, and a Wg gradient can be detected 50 µm from the source (Strigini and Cohen, 2000). The spread-ing of Wg in the wing disc requires the glypican Dlp that binds Wg and promotes Wg signaling in distal cells (Baeg et al., 2001