PLEKHA7 defines an apical junctional complex with cytoskeletal associations and miRNA-mediated growth implications

E-cadherin-p120 catenin complexes are essential for adherens junction (AJ) formation and for the maintenance of the normal epithelial phenotype. PLEKHA7 was originally identified as a member of this complex that tethers microtubules to the AJs and supports their overall integrity. Recently, we revealed that PLEKHA7 regulates cellular behavior via miRNAs by associating with the microprocessor complex at the apical zonula adherens (ZA). We have also identified a new set of PLEKHA7 interacting partners at the apical ZA, via proteomics. Our analysis shows that the main groups of proteins associating with PLEKHA7 are cytoskeletal-related and RNA-binding proteins. Here, we provide extended evidence for association of PLEKHA7 with several of these proteins. We also show that PLEKHA7 loss activates the actin regulator cofilin in a p120-dependent manner, providing an explanation for the effects of PLEKHA7 on the cortical actin ring. Interestingly, PLEKHA7 regulates the levels and associates with PP1α, a phosphatase responsible for cofilin activation. Finally, we clarify the mode of regulation of the oncogenic miR-19a by PLEKHA7. Overall, our findings support a multi-layered role of PLEKHA7 in converging cytoskeletal dynamics and miRNA-mediated growth regulation at the ZA, with potentially critical implications in cancer that warrant further investigation.