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Intercellular Interactions Establishing the Dorsal-ventral Wing Surfaces
The distinction between the dorsal and ventral wing surfaces is a critical one in insect development. This is especially true in the case of butterflies, in which the dorsal and ventral wings can have markedly different pigmentation patterns.
The establishment of the dorsal and ventral compartments of the wing disc appears to occur through multiple interactions between the cells at the border between the apterous-expressing cells, which become the dorsal portion of the wing, and those non-expressing cells, which become the ventral portion of the wing. Many of the signals involved remain undiscovered, but an outline of dorsal-ventral wing formation can be pieced together. This multi-step process is shown in Figure 1.
- Apterous protein activates the fringe gene in the future dorsal wing region of the imaginal disc.
- The Fringe protein is placed on the membrane of these cells.
- The Fringe protein is activated by its receptor on the adjacent, non-apeterous-expressing cell.
- The activated Fringe protein signals the synthesis of the Serrate protein.
- The Serrate protein is placed in the cell membrane of these cells, and it binds to its receptor, Notch.
- The Notch protein signals the synthesis of the Wingless and Vestigial proteins.
- Vestigial protein activates the ventral wing genes in these cells (and probably represses the dorsal wing genes).
- The Wingless protein is synthesized and secreted from the cell.
- Wingless protein binds to its receptor on the adjacent (apterous-expressing) cell.
- The Wingless receptor is activated and transduces a signal activating the dorsal wing-specific genes in the imaginal disc.
|Figure 1 Series of interactions whereby the border cells form the dorsal-ventral boundary. The initiating factor appears to be the presence of the Apterous transcription factor in the future dorsal wing blade cells. (Data from Kim et al. 1995.)|
Kim, J., Irvine, K. D., and Carroll, S. B. 1995. Cell recognition, signal induction, and symmetrical gene activation at the dorsal-ventral boundary of the developing Drosophila wing. Cell 82: 795-802.
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