First published online April 30, 2007
Development 134, 1002e (2007)
© The Company of Biologists Limited
Eyeing-up Wnt-independent pygopus
Pygopus - a core component of the canonical Wnt-signalling pathway - plays
a crucial role in development and disease. Its essential transcriptional
co-activator activity is mediated through its interaction with ß-catenin,
Tcf, Bcl9 and Hyrax. In Xenopus, Pygopus 2 (Pygo2) orthologues
regulate the expression of eye markers. Surprisingly though, it has been
suggested that this activity operates independently of the Wnt pathway.
Richard Lang and co-workers
(p. 1873) now show
that lens development in mice depends on Pygo2-mediated regulation of the
transcription factor Pax6. They further show that Pygo2 function, in this
setting, is Wnt-independent. By conditionally deleting Pygo2 in
certain tissues in mice where it is normally expressed - the ocular mesenchyme
and the presumptive lens ectoderm (PLE) - these researchers show that Pax6
expression is reduced in the PLE and a small lens subsequently develops.
Interestingly, they find that Pygo1 is dispensable for lens development.
Future work should uncover the pathway in which Pygo2 operates during lens
development and reveal whether Pygo2 has other Wnt-independent roles.

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Related articles in Development:
- pygopus 2 has a crucial, Wnt pathway-independent function in lens induction
- Ni Song, Kristopher R. Schwab, Larry T. Patterson, Terry Yamaguchi, Xinhua Lin, Steven S. Potter, and Richard A. Lang
Development 2007 134: 1873-1885.
[Abstract]
[Full Text]