First published online August 14, 2006
Development 133, 1701e (2006)
© The Company of Biologists Limited
Opposing Sax functions set gradient
Patterning of the Drosophila wing imaginal disc involves a Bmp
activity gradient that is created by two Bmp ligands (Gbb and Dpp) and two
type 1 receptors (Tkv and Sax). On
p. 3295, Bangi and
Wharton report that Sax shapes this gradient by both antagonizing and
promoting Bmp signalling. Previous data have suggested that Sax mediates Gbb
signalling while Tkv mediates Dpp signalling; but, puzzlingly, loss of
sax function does not have the same effect as loss of gbb
function. The researchers now show that in the absence of sax
function, the distribution of the downstream effector of Bmp signalling (pMad)
is consistent with an increase in Bmp activity, not a decrease, as expected if
Sax just transduces Gbb signals. The researchers propose that Sax has two
functions: when complexed with itself, Sax antagonizes Bmp signalling by
sequestering Gbb; when complexed with Tkv, it facilitates signalling. The
balance between these functions, they suggest, will shape and stabilize the
Bmp activity gradient across the developing wing.
Related articles in Development:
- Dual function of the Drosophila Alk1/Alk2 ortholog Saxophone shapes the Bmp activity gradient in the wing imaginal disc
- Erdem Bangi and Kristi Wharton
Development 2006 133: 3295-3303.
[Abstract]
[Full Text]
