The spatial regulation of cellular Rho signaling by GAP proteins is still poorly understood. By mass spectrometry we here identify the polarity protein Scribble as a scaffold for the RhoGAP protein DLC3 at cell-cell adhesions. This mutually dependent interaction is mediated by the PDZ domains of Scribble and a PDZL motif in DLC3. Both Scribble depletion and PDZL deletion abrogated DLC3 junctional localization. Using a RhoA biosensor and a targeted GAP domain, we demonstrate that DLC3 activity locally regulates RhoA-ROCK signaling at and Scribble localization to adherens junctions and is required for their functional integrity. In a 3D model of cyst development, we furthermore show that DLC3 depletion impairs polarized morphogenesis, phenocopying the effects observed upon Scribble knockdown. We thus propose a novel function for Scribble in Rho regulation that entails positioning of DLC3 GAP activity at cell junctions in polarized epithelial cells.
- Received March 31, 2016.
- Accepted August 1, 2016.
- © 2016. Published by The Company of Biologists Ltd