Involvement of vesicle-cytoskeleton interaction in AQP5 trafficking in AQP5-gene-transfected HSG cells.

A cDNA of rat aquaporin 5 (AQP5) was used to transfect to HSG (human salivary gland cells), and the trafficking mechanism was studied in vitro by confocal laser microscopy. The trafficking of AQP5 to the plasma membrane was induced by stimulation of AQP5-gene-transfected human salivary gland cells (HSGAQP5 cells) with thapsigargin, an inhibitor of endoplasmic Ca(2+)-ATPase, and or with A-23187, a calcium ionophore. Pretreatment of these cells with colchicine or vinblastine, microtubule inhibitors, prevented the trafficking induced by thapsigargin or A-23187. The trafficking event was not completely inhibited by cytochalasin B, a microfilament inhibitor. These results demonstrate that the trafficking of AQP5 vesicles to the plasma membrane is triggered by an increase in intracellular Ca(2+) and that the interaction of AQP5-containing vesicles with the cytoskeleton is involved in this trafficking.