Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
XB-ART-8355
Development September 1, 2001; 128 (18): 3635-47.

Regulation of cell polarity, radial intercalation and epiboly in Xenopus: novel roles for integrin and fibronectin.



Abstract
Fibronectin (FN) is reported to be important for early morphogenetic movements in a variety of vertebrate embryos, but the cellular basis for this requirement is unclear. We have used confocal and digital time-lapse microscopy to analyze cell behaviors in Xenopus gastrulae injected with monoclonal antibodies directed against the central cell-binding domain of fibronectin. Among the defects observed is a disruption of fibronectin matrix assembly, resulting in a failure of radial intercalation movements, which are required for blastocoel roof thinning and epiboly. We identified two phases of FN-dependent cellular rearrangements in the blastocoel roof. The first involves maintenance of early roof thinning in the animal cap, and the second is required for the initiation of radial intercalation movements in the marginal zone. A novel explant system was used to establish that radial intercalation in the blastocoel roof requires integrin-dependent contact of deep cells with fibronectin. Deep cell adhesion to fibronectin is sufficient to initiate intercalation behavior in cell layers some distance from the substrate. Expression of a dominant-negative beta1 integrin construct in embryos results in localized depletion of the fibronectin matrix and thickening of the blastocoel roof. Lack of fibronectin fibrils in vivo is correlated with blastocoel roof thickening and a loss of deep cell polarity. The integrin-dependent binding of deep cells to fibronectin is sufficient to drive membrane localization of Dishevelled-GFP, suggesting that a convergence of integrin and Wnt signaling pathways acts to regulate radial intercalation in Xenopus embryos.

PubMed ID: 11566866
Article link: Development
Grant support: [+]
Genes referenced: bcr dvl1 dvl2 fn1 gnao1 itgb1


Article Images: [+] show captions


Xenbase: The Xenopus Model Organism Knowledgebase.
Version: 4.14.0
Major funding for Xenbase is provided by grant P41 HD064556