WNT SIGNALING AND AN APC-RELATED GENE SPECIFY ENDODERM IN EARLY C-ELEGANS EMBRYOS

In a 4-cell stage C. elegans embryo, signaling by the P-2 blastomere i nduces anterior-posterior polarity in the adjacent EMS blastomere, lea ding to endoderm formation. We have taken genetic and reverse genetic approaches toward understanding the molecular basis for this induction . These studies have identified a set of genes with sequence similarit y to genes that have been shown to be, or are implicated in, Wnt/Wingl ess signaling pathways in other systems. The C. elegans genes describe d here are related to wnt/wingless,porcupine, frizzled, beta-catenin/a rmadillo, and the human adenomatous polyposis coil gene, APC. We prese nt evidence that there may be partially redundant inputs into endoderm specification and that a subset of these genes appear also to functio n in determining cytoskeletal polarity in certain early blastomeres.