Association of Rho-associated protein kinase 1 with E-cadherin complexes is mediated by p120-catenin

The dynamic functional linkage of cadherins with the underlying actin cytoskeleton is tightly regulated to achieve proper cell-cell adhesion. p120-catenin (p120) regulates both cadherin stability and actin dynamics, but the relationship between these two functions remains unclear. Using a novel proteomic approach called reversible cross-link immunoprecipitation, or ReCLIP, we previously identified a physical interaction between p120 and Rho-associated protein kinase 1 (ROCK1), a major effector of RhoA. In this paper, we show that a discrete fraction of cellular ROCK1 coimmunoprecipitates with p120 and precisely colocalizes to adherens junctions (AJs). Manipulation of AJs using a calcium-switch assay and cadherin-blocking antibodies indicates direct recruitment of ROCK1 to newly forming junctions. Importantly, we find that p120 links ROCK1 to the cadherin complex, as ROCK1 coimmunoprecipitates with wild-type but not p120-uncoupled E-cadherin. Moreover, depletion of ROCK1 using short-hairpin RNA results in dramatic mislocalization of the cadherin complex and junctional actin. These data are consistent with a model in which p120 dynamically regulates Rho-GTPase activity at the cadherin complex through transient interaction with several of its up-and downstream effectors, including ROCK1.