First published online December 20, 2005
Development 133, 203e (2006)
© The Company of Biologists Limited
How flies spread their Wingless
Morphogen gradients are shaped by several dynamic processes, and on
p. 307, Suzanne Eaton
and colleagues determine the contribution of endocytosis to the maintenance of
the Wingless (Wg) gradient, which is secreted at the dorsal-ventral boundary
of the Drosophila melanogaster wing disc. Endocytosis requires the
Rab GTPases, and specific endosomes are associated with specific Rab proteins.
So the researchers used dominant-negative Rab proteins to disrupt particular
branches of the endocytic pathway, and found that preventing Wg endocytosis
increased its extracellular spread. Curiously, although overexpression of the
glypican Dally-like (Dlp) - which is required for long-range Wg movement -
caused the accumulation of extracellular Wg, it was not required for the
spread of Wg when endocytosis was blocked. The authors report that Wg is only
internalized from the apical and basal surfaces of the disc, and propose that
Dlp promotes the spread of Wg by directing it to lateral membranes, where it
is endocytosed less
efficiently.
Related articles in Development:
- The endocytic pathway and formation of the Wingless morphogen gradient
- Eric Marois, Ali Mahmoud, and Suzanne Eaton
Development 2006 133: 307-317.
[Abstract]
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