Bradykinin induces formation of vesicle-like structures containing vinculin and PtdIns(4,5)P₂in renal papillary collecting duct cells

Abstract

Focal adhesions (FAs) are structures of cell attachment to the extracellular matrix. We previously demonstrated that the intrarenal hormone bradykinin (BK) induces the restructuring of FAs in papillary collecting duct cells by dissipation of vinculin, but not talin, from FAs through a mechanism that involves PLCbeta activation, and that it also induces actin cytoskeleton reorganization. In the present study we investigated the mechanism by which BK induces the dissipation of vinculin-stained FAs in collecting duct cells. We found that BK induces the internalization of vinculin by a noncaveolar and independent pinocytic pathway and that at least a fraction of this protein is delivered to the recycling endosomal compartment, where it colocalizes with the transferrin receptor. Regarding the reassembly of vinculin-stained FAs, we found that BK induces the formation of phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2]-enriched vinculin-containing vesicles, which, by following a polarized exocytic route, transport vinculin to the site of FA assembly, an action that depends on actin filaments. The present study, which was carried out with cells that were not genetically manipulated, shows for the first time that BK induces the formation of vesicle-like structures containing vinculin and PtdIns(4,5)P2, which transport vinculin to the site of FA assembly. Therefore, the modulation of the formation of these vesicle-like structures could be a physiological mechanism through which the cell can reuse the BK-induced internalized vinculin to be delivered for newly forming FAs in renal papillary collecting duct cells.

A Structural Model for Vinculin Insertion into PIP2-Containing Membranes and the Effect of Insertion on Vinculin Activation and Localization

“…While association of Vcl with PIP 2 has been implicated in numerous processes including cell spreading, cell migration, FA turnover, and force transduction (Chandrasekar et al, 2005; Chinthalapudi et al, 2014; Diez et al, 2009; Saunders et al, 2006), the Vcl constructs used in these studies may not be selective in their disruption of PIP 2 -binding. Additionally, PIP 2 has been reported to regulate Vcl phosphorylation (Ziegler et al, 2002) and trafficking (Halstead et al, 2010; Marquez et al, 2009). …”