First published online November 10, 2005
Development 132, 2304e (2005)
© The Company of Biologists Limited
Ubx: a case study for selector protein evolution
The misregulation or misexpression of selector proteins - transcription
factors that regulate batteries of target genes during development - can
change the identities of cells and tissues, and the shape of whole
organisms.
Consequently, the functional domains of selector proteins are highly
conserved. Researchers now provide new insights into how conserved peptide
motifs in the Drosophila Hox protein Ultrabithorax (Ubx) mediate
different aspects of its function. By both activating and repressing
transcription, Ubx controls many morphogenetic decisions in fly embryos,
including limb formation, which it prevents by repressing Distal-less
transcription. On p.
5271, Tour and
co-workers investigate several conserved motifs within Ubx that are required
for its activation and repression functions. They find that the activation
function of Ubx is mediated by an N-terminal motif that is conserved between
fly and human Hox proteins, and show that its repressive functions are
concentration dependent and involve multiple domains, including the conserved
YPWM motif. On p.
5261, Hittinger and
colleagues report that the conserved QA peptide in Ubx - originally identified
as a motif required for limb repression - has different effects in different
tissues. In addition, they show that the requirement for QA in limb repression
is dose dependent and partly redundant with Abd-A, another Hox protein.
Overall, the researchers suggest that the additive and redundant effects of
protein motifs in Ubx, and more generally in other selector proteins, might be
important in modulating the effects of their evolution.
Related articles in Development:
- Pleiotropic functions of a conserved insect-specific Hox peptide motif
- Chris Todd Hittinger, David L. Stern, and Sean B. Carroll
Development 2005 132: 5261-5270.
[Abstract]
[Full Text]
- Evolutionarily conserved domains required for activation and repression functions of the Drosophila Hox protein Ultrabithorax
- Ella Tour, Chris Todd Hittinger, and William McGinnis
Development 2005 132: 5271-5281.
[Abstract]
[Full Text]
