Brabazon, Elaine

Cellular Adhesion in the Developing Embryo

Morphogenesis in embryos is the consequence of the precise spatio-temporal expression of the molecules that control cell adhesion, cell motility and orientated cell division. Cell surface adhesion proteins, including the cadherins and their associated catenins are involved in mediating critical events during cell development. Indeed, mouse embryos which lack the cadherins fail to form trophoectodermal epithelium and die around the time of implantation (Larue et al., 1994). Furthermore, embryonic neuralation and somitogenesis necessitates the correct expression and localisation of the cadherin family of proteins. It would seem therefore that the cadherins and their associated proteins are critical in directing early embryonic development and in the maintaneance of subsequent tissue architecture.

Investigation of the dynamics of cadherin movement within the lipid bilayer and their interaction with adhesion molecules on adjacent cells, would promote a significant understanding of embryonic development. In addition, the specific role of the catenin family of proteins during organogenesis is of interest. These proteins appear to link certain cadherins to the actin cytoskeleton but they are also involved in the Wnt signalling pathway - a highly conserved pathway implicated in, among other things, the development of the central nervous system in mammals. However, the inter-relationship between the dual functions of the catenins (namely their involvement in cadherin mediated cell-cell adhesion and their role in the regulation of transcription) is not very well understood at present. Furthermore, the role of calcium in the mediation of the adhesive events during development has not been addressed fully. Using Zebrafish (Danio Rerio) as a model for vertebrate embryo development, we aim to explore the localisation and function the cadherins and catenins during animal morphogenesis.