Zecca Myriam, Struhl Gary
Howard Hughes Medical Institute, Department of Genetics and Development, Columbia University College of Physicians and Surgeons, 701 W 168th Street, New York, NY 10032, USA.
Development. 2007 Aug;134(16):3001-10. doi: 10.1242/dev.006411. Epub 2007 Jul 18.
The Drosophila wing primordium is defined by expression of the selector gene vestigial (vg) in a discrete subpopulation of cells within the wing imaginal disc. Following the early segregation of the disc into dorsal (D) and ventral (V) compartments, vg expression is governed by signals generated along the boundary between the two compartments. Short-range DSL (Delta/Serrate/LAG-2)-Notch signaling between D and V cells drives vg expression in ;border' cells that flank the boundary. It also induces these same cells to secrete the long-range morphogen Wingless (Wg), which drives vg expression in surrounding cells up to 25-30 cell diameters away. Here, we show that Wg signaling is not sufficient to activate vg expression away from the D-V boundary. Instead, Wg must act in combination with a short-range signal produced by cells that already express vg. We present evidence that this vg-dependent, vg-inducing signal feeds forward from one cell to the next to entrain surrounding cells to join the growing wing primordium in response to Wg. We propose that Wg promotes the expansion of the wing primordium following the D-V segregation by fueling this non-autonomous autoregulatory mechanism.
果蝇翅原基由翅成虫盘内离散细胞亚群中选择基因“痕迹”（vg）的表达所界定。在成虫盘早期分为背（D）腹（V）两区后，vg的表达受两区之间边界处产生的信号调控。D区和V区细胞之间的短程DSL（Delta/锯齿状蛋白/LAG-2）-Notch信号驱动边界两侧“边界”细胞中的vg表达。它还诱导这些相同的细胞分泌远程形态发生素无翅蛋白（Wg），Wg可驱动距离边界达25 - 30个细胞直径范围内的周围细胞中的vg表达。在此，我们表明Wg信号不足以在远离D-V边界处激活vg表达。相反，Wg必须与已表达vg的细胞产生的短程信号共同作用。我们提供的证据表明，这种依赖vg且诱导vg的信号从前一个细胞向前馈送到下一个细胞，以带动周围细胞响应Wg加入不断生长的翅原基。我们提出，Wg通过推动这种非自主的自调节机制来促进D-V分离后翅原基的扩展。
