Regulation of Cytoskeleton In Early Xenopus Development
Qinhua Tao, Sumeda Nanadadas, and Chris Wylie
Figures
Fig. 1 The cortical actin skeleton of the blastula stage embryo. Each cell has a dense network of actin filaments in its cortex.
Fig. 2 Lipid signaling is also required for cortical actin assembly. Here, the receptor for lysophosphatidic acid has been targeted, and causes a failure of cortical actin assembly.
Actin assembly is essential for almost all cellular functions, and many congenital disorders of children are caused by defects in actin functions such as cell motility. Despite its importance, there is surprisingly little known about how the actin skeleton is assembled in the early embryo, or changes as groups of cells initiate, perform, or stop, their morphogenetic movements. We are using the early Xenopus embryo to identify the molecular mechanism of actin assembly. We have found that the shape and rigidity of the embryo at the blastula stage depends upon a dense network of cortical actin filaments in each cell of the embryo. We have found that the density of this network of filaments is controlled by signaling through G-protein coupled receptors, and one aspect of the project is to identify how these signals are transduced into actin assembly. Xenopus is a very useful model organism for this. It is an in vivo system, in which the consequences of loss of cortical actin can be easily assayed (failure of cellular movements, and loss of embryo architecture). The functions of individual proteins can be rapidly assayed by loss of function experiments.
Fig. 3 Embryos lose their shape and rigidity due to loss of cortical actin, when a single G-protein coupled receptor is targeted.
Recent Publications
Tao QH, Nandadasa S, McCrea P, Heasman J and Wylie C. (2006) G protein-coupled signals control cortical actin assembly by controlling cadherin expression in the early Xenopus embryo. Development (under revision).
Tao QH, Lloyd B, Lang S, Houston D, Zorn A, and Wylie C. (2005). A novel G protein coupled receptor, related to GPR4, is required for assembly of the cortical actin in early Xenopus embryos. Development. 132:2825-2836.
Lloyd B, Tao QH, Lang S and Wylie C (2005). Lysophosphatidic acid signaling controls actin assembly and cytoarchiteture in Xenopus embryos. Development. 132:805-816.
Kofron M, Heasman J, Lang S and Wylie C (2002). Plakoglobin is required for maintenance of the cortical actin skeleton in early Xenopus embryos and for cdc42-mediated wound healing. Journal of Cell Biology 158(4): 695-708.
