spacer gif spacer gif spacer gif spacer gif ARCHIVE ANNOUNCEMENT! spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

First published online 3 July 2006
doi: 10.1242/dev.02460

Development 133, 2905-2913 (2006)
Published by The Company of Biologists 2006
This Article
Right arrow Figures Only
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
dev.02460v1
133/15/2905    most recent
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Alexandre, P.
Right arrow Articles by Wassef, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Alexandre, P.
Right arrow Articles by Wassef, M.

Positive and negative regulations by FGF8 contribute to midbrain roof plate developmental plasticity

Paula Alexandre*, Isabelle Bachy, Morgane Marcou and Marion Wassef{dagger}

Régionalisation Nerveuse CNRS/ENS UMR 8542, Département de Biologie, Ecole normale supérieure, 46 rue d'Ulm, 75005 Paris, France.

{dagger} Author for correspondence (e-mail: wassef{at}wotan.ens.fr)

Accepted 25 May 2006

The roof plate (RP) of the midbrain shows an unusual plasticity, as it is duplicated or interrupted by experimental manipulations involving the mid/hindbrain organizer or FGF8. In previous experiments, we have found that FGF8 induces a local patterning center, the isthmic node, that is essential for the local development of a RP. Here, we show that the plasticity of the midbrain RP derives from two apparently antagonistic influences of FGF8. On the one hand, FGF8 widens beyond the neural folds the competence of the neuroepithelium to develop a RP by inducing the expression of LMX1B and WNT1. Ectopic overexpression of these two factors is sufficient to induce widely the expression of markers of the mature RP in the midbrain. On the other hand, FGF8 exerts a major destabilizing influence on RP maturation by controlling signaling by members of the TGFß superfamily belonging to the BMP, GDF and activin subgroups. We show in particular that FGF8 tightly modulates follistatin expression, thus progressively restraining the inhibitory influence of activin B on RP differentiation. These regulations, together with FGF8 triggered apoptosis, allow the formation of a RP progress zone at some distance from the FGF8 source. Posterior elongation of the RP is permitted when the source of FGF8 withdraws. Growth of the posterior midbrain neuroepithelium and convergent extension movements induced by FGF8 both contribute to increase the distance between the source of FGF8 and the maturing RP. Normally, the antagonistic regulatory interactions spread smoothly across the midbrain. Plasticity of midbrain RP differentiation probably results from an experimentally induced imbalance between regulatory pathways.

Key words: Isthmic organizer, Mid/hindbrain organizer, Roof plate, FGF8, Follistatin, Activin, BMP7, GDF7, Chick, Quail




This article has been cited by other articles:


Home page
 DevelopmentHome page
M. A. Basson, D. Echevarria, C. Petersen Ahn, A. Sudarov, A. L. Joyner, I. J. Mason, S. Martinez, and G. R. Martin
Specific regions within the embryonic midbrain and cerebellum require different levels of FGF signaling during development
Development, March 1, 2008; 135(5): 889 - 898.
[Abstract] [Full Text] [PDF]


© The Company of Biologists Ltd 2006