Rho1 interacts with p120ctn and α-catenin, and regulates cadherin-based adherens junction components in Drosophila

Abstract

Rho GTPases are important regulators of cellular behavior through their effects on processes such as cytoskeletal organization. Here we show interactions between Drosophila Rho1 and the adherens junction components α-catenin and p120ctn. We find that while Rho1 protein is present throughout the cell, it accumulates apically, particularly at sites of cadherin-based adherens junctions. Cadherin and catenin localization is disrupted in Rho1 mutants, implicating Rho1 in their regulation. p120ctn has recently been suggested to inhibit Rho activity through an unknown mechanism. We find that Rho1 accumulates in response to lowered p120ctn activity. Significantly, we find that Rho1 binds directly to α-catenin and p120ctn in vitro, and these interactions map to distinct surface-exposed regions of the protein not previously assigned functions. In addition, we find that both α-catenin and p120ctn co-immunoprecipitate with Rho1-containing complexes from embryo lysates. Our observations suggest that α-catenin and p120ctn are key players in a mechanism of recruiting Rho1 to its sites of action.