Márquez María Gabriela, Fernández-Tome María del Carmen, Favale Nicolás Octavio, Pescio Lucila Gisele, Sterin-Speziale Norma Beatriz
Instituto de Investigaciones en Ciencias de la Salud Humana, Universidad Nacional de La Rioja, La Rioja, Argentina.
Am J Physiol Renal Physiol. 2009 Nov;297(5):F1181-91. doi: 10.1152/ajprenal.00062.2009. Epub 2009 Sep 16.
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.
粘着斑（FAs）是细胞附着于细胞外基质的结构。我们之前证明，肾内激素缓激肽（BK）通过使粘着斑中的纽蛋白（而非踝蛋白）消散，经由涉及磷脂酶Cβ（PLCβ）激活的机制，诱导乳头集合管细胞中粘着斑的重组，并且它还诱导肌动蛋白细胞骨架的重组。在本研究中，我们探究了BK诱导集合管细胞中纽蛋白染色的粘着斑消散的机制。我们发现，BK通过非小窝依赖性胞饮途径诱导纽蛋白内化，并且该蛋白的至少一部分被递送至再循环内体区室，在那里它与转铁蛋白受体共定位。关于纽蛋白染色的粘着斑的重新组装，我们发现BK诱导富含磷脂酰肌醇4,5-二磷酸[PtdIns(4,5)P2]的含纽蛋白囊泡的形成，这些囊泡通过极化的胞吐途径将纽蛋白转运至粘着斑组装位点，这一作用依赖于肌动蛋白丝。本研究是在未进行基因操作的细胞上进行的，首次表明BK诱导形成含有纽蛋白和PtdIns(4,5)P2的囊泡样结构，这些结构将纽蛋白转运至粘着斑组装位点。因此，调节这些囊泡样结构的形成可能是一种生理机制，通过该机制细胞可以重新利用BK诱导内化的纽蛋白，以递送至肾乳头集合管细胞中新生的粘着斑。
