A negative modulatory role for Rho and Rho-associated kinase signaling in delamination of neural crest cells
Neural crest progenitors arise as epithelial cells and then undergo a process of epithelial to mesenchymal transition that precedes the generation of cellular motility and subsequent migration. We aim at understanding the underlying molecular network.
Along this line, possible roles of Rho GTPases that act as molecular switches to control a variety of signal transduction pathways, remain virtually unexplored, and so are putative interactions between Rho proteins an additional known components of this cascade.
Results: We investigated the role of Rho/Rock signaling in neural crest delamination. RhoA and RhoB are expressed in the membrane of epithelial progenitors from which they are downregulated upon delamination.
In vivo loss-of-function of RhoA or RhoB or of overall Rho signaling by C3 transferase enhanced delamination. Consistently, treatment of explanted neural primordia with membrane-permeable C3 or with the Rock inhibitor Y27632 both accelerated and enhanced crest emigration.
These treatments altered neural crest morphology by reducing stress fibers, focal adhesions and downregulating N-cadherin. Reciprocally, activation of endogenous Rho by lysophosphatidic acid inhibited emigration while enhancing the above.
Since delamination is triggered by BMP and requires G1/S transition, we examined their relationship with Rho. Blocking Rho/Rock function rescued crest delamination upon treatment with noggin or with the G1/S inhibitor mimosine.
In the latter condition, cells emigrated while arrested at G1.
Conclusions: Rho-GTPases, through Rock, act downstream of BMP and of G1/S transition to negatively regulate crest delamination by modifying cytoskeleton assembly and intercellular adhesion.
Author: Maya Groysman, Irit Shoval and Chaya Kalcheim
Credits/Source: Neural Development 2008, 3:27
Published on: 2008-10-22
Copyright by the authors listed above - made available via BioMedCentral (Open Access). Please
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