First published online August 25, 2006
Development 133, 1802e (2006)
© The Company of Biologists Limited
A Snail trail to Wg-induced death
The periphery of the fly eye is a good place to study the final stage of
positional signalling. Here, Wingless (Wg) signalling induces concentrically
arranged cellular specializations, such as the pigment rim, which shields the
eye from extraneous light. The pigment cells that form this structure
originally surrounded the peripheral ommatidia of the eye, which die during
pupal eye development. On p.
3529, Lim and Tomlinson report that three Snail family transcription
factors - Worniu, Snail and Escargot - and the enzyme Notum are Wg signalling
targets at the edge of the fly eye. Notum limits the extent of Wg signalling,
but Snail gene expression, they report, is required for removing the
peripheral ommatidia and for forming the peripheral rim. Because Snail family
proteins are expressed only in a subset of ommatidia cells, not in the
photoreceptors that die, Lim and Tomlinson propose that a death signal
released from the Snail-family-expressing cells directs the death of the
photoreceptors.
Related articles in Development:
- Organization of the peripheral fly eye: the roles of Snail family transcription factors in peripheral retinal apoptosis
- Hui-Ying Lim and Andrew Tomlinson
Development 2006 133: 3529-3537.
[Abstract]
[Full Text]
