Catenins (α-, β- and γ- or plakoglobin) are cytoplasmic cadherin-associated proteins. Studies on cultured cells have suggested that both α-catenin and plakoglobin are important for the adhesive function of cadherins. α-catenin binds to both β-catenin and plakoglobin and may link the cadherin/catenin complex to actin filaments. Separate domains of plakoglobin bind to cadherin and α-catenin, suggesting it may act as a bridge between these molecules. However, plakoglobin may have other activities: it is expressed in both desmosomal junctions in association with desmogleins and the cytoplasm in conjunction with APC, and previous work suggests it may act in a dorsal signalling pathway when overexpressed in Xenopus embryos. Here, we have studied the roles of α-catenin and plakoglobin directly, by depleting the maternal mRNAs coding for each of them in developing Xenopus embryos. We find that depletion of maternal α-catenin causes the loss of intercellular adhesion at the blastula stage, similar to that reported previously for EP cadherin. Depletion of plakoglobin results in a partial loss of adhesion, and a loss of embryonic shape, but does not affect dorsal signalling.

Keywords:
α-catenin, plakoglobin, intercellular adhesion, cadherin, maternal α-catenin, Xenopus
© 1997 by Company of Biologists
1997
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