Localized activation of m-calpain in migrating human umbilical vein endothelial cells stimulated by shear stress

Using a parallel-plate flow-chamber and confocal laser scanning microscopy (CLSM), we studied the mode of cytoskeletal reorganization in migrating HUV ECs stimulated by shear stress. Activation of m-calpain associated with a c hange in the spatial distribution of cytoplasmic ionized Ca2+ concentration ([Ca2+](i)) was studied. Shear stress (10 dyne/cm(2)) caused migration and decrease in the F-actin content of HUVECs. Migrating individual HUVECs sho wed the lamellipodium formed in the direction of cell migration, in which [ Ca2+](i) elevated to 148 +/- 12 nM in a localized fashion. We found the app earance of activated m-calpain in the local area of the migrating HUVECs, w hich was associated with a decrease in the amounts of pp125FAK and ezrin. T he localized rise in [Ca2+](i) might he closely related to morphological ch ange to regulate the direction of cell migration induced by shear stress th rough localized activation of m-calpain. (C) 2001 Wiley-Liss. Inc.