A PUTATIVE CATENIN-CADHERIN SYSTEM MEDIATES MORPHOGENESIS OF THE CAENORHABDITIS-ELEGANS EMBRYO

During morphogenesis of the Caenorhabditis elegans embryo, hypodermal (or epidermal) cells migrate to enclose the embryo in an epithelium an d, subsequently, change shape coordinately to elongate the body (Pries s, J.R., and D.I. Hirsh. 1986, Dev. Biol. 117:156-173, Williams-Masson , E.M., A.N. Malik, and J. Hardin. 1997, Development [Camb.]. 124:2889 -2901). We have isolated mutants defective in morphogenesis that ident ify three genes required for both cell migration during body enclosure and cell shape change during body elongation. Analyses of hmp-1, hmp- 2, and hmr-1 mutants suggest that products of these genes anchor contr actile actin filament bundles at the adherens junctions between hypode rmal cells and, thereby, transmit the force of bundle contraction into cell shape change. The protein products of all three genes localize t o hypodermal adherens junctions in embryos. The sequences of the predi cted HMP-1, HMP-2, and HMR-1 proteins are related to the cell adhesion proteins alpha-catenin, beta-catenin/Armadillo, and classical cadheri n, respectively. This putative catenin-cadherin system is not essentia l for general cell adhesion in the C. elegans embryo, but rather media tes specific aspects of morphogenetic cell shape change and cytoskelet al organization.