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In-Depth Information
inactivated by the distal proteins (
Fig. 1.6
). If the distal target is an activator,
then we can predict that a loss-of-function mutation would result in del-
ayed hair initiation and perhaps small or short hairs. Several such genes
have been reported including
shavenoid
which has a strong hair delay/loss
phenotype (
Ren, He, Stone, Kirakodu, & Adler, 2006
). However, the
phenotype of null alleles of
sha
is strongly enhanced by cells simultaneously
being mutant for
fz/stan
pathway genes. Thus, if Sha is a target it cannot be
the only one. Other possible activator targets are proteins that modulate the
activity of the actin cytoskeleton such as formins (
Campellone & Welch,
2011; Chesarone et al., 2011; Goode & Eck, 2007
) or the Arp23
complex (
Campellone & Welch, 2011; Zigmond, 2004
). No evidence
suggesting this is the case has been published. It is also possible that the
target is an inhibitor, and if so, we can predict that loss-of-function
mutations would result in premature hair initiation. No possible targets
with this property have been reported.
ACKNOWLEDGMENTS
The author is supported by a grant from the NIGMS (GM-37136). I thank Simon Collier for
generously providing the images of wing ridges.
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