First published online September 26, 2008
Development 135, 2001e (2008)
© The Company of Biologists Limited
Semaphorin applies brakes to branching morphogenesis
Semaphorins are secreted signals that function during diverse developmental
events, from axon guidance to angiogenesis. Although the plexin A family of
semaphorin receptors has been well characterised, less is known about the
B-type plexins, particularly their roles in organogenesis. Now Korostylev et
al. have discovered that the Sema4d-plexin B1 ligand-receptor pair negatively
regulates branching morphogenesis during kidney development by RhoA-ROCK
pathway activation (see p.
3333). By analysing the expression of this pair in developing organs,
the authors found that plexin B1 and Sema4d are expressed in epithelial and
mesenchymal compartments, respectively, implicating them in the
epithelial-mesenchymal interactions that occur during organogenesis. Next, in
cultured mouse embryonic kidneys, they found that exogenously applied Sema4d
reduces ureteric branching and activates RhoA. However, when they blocked the
RhoA-ROCK pathway, Sema4d stimulated ureteric branching. From these findings,
the authors conclude that RhoA-ROCK signalling acts as an endogenous brake on
plexin B1-triggered, branch-promoting signalling through a function that is
distinct from ROCK's maintenance of the cytoskeletal structure of the ureteric
tree.

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Related articles in Development:
- A functional role for semaphorin 4D/plexin B1 interactions in epithelial branching morphogenesis during organogenesis
- Alexander Korostylev, Thomas Worzfeld, Suhua Deng, Roland H. Friedel, Jakub M. Swiercz, Peter Vodrazka, Viola Maier, Alexandra Hirschberg, Yoshiharu Ohoka, Shinobu Inagaki, Stefan Offermanns, and Rohini Kuner
Development 2008 135: 3333-3343.
[Abstract]
[Full Text]