ZFIN ID: ZDB-PUB-021017-57
Regulation of cell polarity during zebrafish gastrulation
Solnica-Krezel, L., Marlow, F., Topczewski, J., Jessen, J., and Sepich, D.
Date: 2002
Source: Developmental Biology   247(2): 479 (Abstract)
Registered Authors: Jessen, Jason R., Marlow, Florence, Sepich, Diane, Solnica-Krezel, Lilianna, Topczewski, Jacek
Keywords: none
MeSH Terms: none
PubMed: none
ABSTRACT
During the vertebrate gastrulation movements of convergence and extension (C&E) the entire embryo and most organ rudiments narrow along the mediolateral axis while extending their anterior–posterior dimension. In zebrafish C&E movements are driven by directed cell migration and mediolateral intercalation of polarized cells and require noncanonical Wnt signaling. Mutations in knypek gene encoding a member of the glypican family of heparan sulfate proteoglycans impair C&E movements due to abnormal cell polarity, as mutant cells fail to elongate and align mediolaterally. Knypek potentiates Silberblick (Wnt11) signaling mediating C&E via a noncanonical signal transduction cascade. Mosaic analyses demonstrate that knypek has both cell-autonomous and nonautonomous roles in cell polarity determination. Zebrafish Rho kinase ? (Rok2) is expressed in zebrafish gastrula and overexpression of a dominant-negative Rok2 (dnRok2) disrupts C&E, phenocopying noncanonical Wnt signaling mutants. Epistatic analyses place Rok2 downstream of Wnt 11 in regulation of C&E. Impaired dorsal convergence movements in Rok2-deficient embryos are associated with defective cell polarity and consequently inability of a cell to migrate persistently dorsally along straight path. Transplantation experiments reveal both cell-autonomous and cell nonautonomous roles for Rok2 function during cell elongation and orientation.
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