ABSTRACT
Focal adhesions (FAs) are specialized regions of cell attachment to the extracellular matrix. Previous works have suggested that bradykinin (BK) can modulate cell-matrix interaction. In the present study, we used a physiological cellular model to evaluate the potential role of BK in modulating FAs and stress fibers. We performed a quantitative morphometric analysis of FAs in primary cultured rat renal papillary collecting duct cells, which included size, axial ratio (shape), and average length. After 1, 5, or 10 min of incubation with BK, cultured cells were immunostained and analyzed by confocal microscopy. Although the shape of FAs was not altered, BK induced a decrease in the number of vinculin-stained FAs per cell, and a decrease in both their size and their average length, but not in talin-containing FAs, thus suggesting that BK could be inducing a restructuring of FAs. BK also induced a remodeling of the actin filament assemblies rather than their dissipation. Since we have previously demonstrated that BK stimulates activation of PLCbeta in rat renal papillae, we attempted to determine whether BK can modulate FA restructuring by this mechanism, by pretreating cultured cells with the PLCbeta inhibitor U73122. The present study, performed under physiological conditions with cells that were not genetically manipulated, provides new experimental evidence supporting the notion that the intrarenal hormone BK modulates FAs and actin cytoskeleton organization through a mechanism that involves the activation of PLCbeta. We propose this finding as a novel mechanism for BK modulation of tubular collecting duct function.
