First published online January 27, 2005
Development 132, 404e (2005)
© The Company of Biologists Limited
Dally and Dally-like functions: some questions answered
Heparan sulphate proteoglycans (HSPGs) – extracellular molecules that
bind key secreted morphogens, including Wingless (Wg) and Hedgehog (Hh)
– are crucial for normal metazoan development. But pinning down their
roles in different signalling pathways can be extremely difficult. For
example, it has been recently debated (see Development 131,
2509), whether the fly HSPGs,
Dally and Dally-like protein (Dlp), function in both Hh and Wg, or just in Hh,
signalling. Now, Franch-Marro et al., on p.
659, conclusively
answer this question. By generating dally and dlp null
mutant flies, they show that neither Dally nor Dlp is essentially required for
embryonic Wg signalling. If wg expression is sustained in double
mutant embryos, Wg pathway activation still occurs. By contrast, Dlp has a
crucial role in regulating the range of Wg signalling in the wing imaginal
discs of developing larvae. The authors report that in the absence of Dlp,
short-range Wg signalling in this tissue increases at the expense of
long-range signalling. To explain this, they propose that here Dlp functions
by passing bound Wg onto neighbouring cells rather than to signalling
receptors on the same cell, but how this actually occurs requires more
investigation. Dally appears to act as a non-essential co-receptor that binds
and presents Wg to signalling receptors on the same cell. On p.
667, Han et al. also
shed light on Dally and Dlp functions in wing development. They report that it
is predominantly the combined actions of Dally and Dlp that shape the Wg
gradient in the developing fly wing by a restricted diffusion mechanism.
Contradicting previous findings, they also report that the Wg receptor Fz2
appears to have only a modest role in this process.
Related articles in Development:
- Glypicans shunt the Wingless signal between local signalling and further transport
- Xavier Franch-Marro, Oriane Marchand, Eugenia Piddini, Sara Ricardo, Cyrille Alexandre, and Jean-Paul Vincent
Development 2005 132: 659-666.
[Abstract]
[Full Text]
- Drosophila glypicans Dally and Dally-like shape the extracellular Wingless morphogen gradient in the wing disc
- Chun Han, Dong Yan, Tatyana Y. Belenkaya, and Xinhua Lin
Development 2005 132: 667-679.
[Abstract]
[Full Text]
