DISRUPTION OF THE GOLGI-APPARATUS BY BREFELDIN-A BLOCKS CELL POLARIZATION AND INHIBITS DIRECTED CELL-MIGRATION

The role of the Golgi apparatus in the motile activity of fibroblasts was examined with brefeldin A (BFA), which disrupts the Golgi apparatu s in a variety of cells. Upon incubation with BFA, Swiss mouse 3T3 fib roblasts lost their typical polarized morphology, in which the leading edge is characterized by intensive lamellipodia formation. BFA affect ed cell asymmetry as demonstrated by a decrease in the morphometric in dices, dispersion, and elongation. After BFA treatment, cells showed l ittle protrusional activity and did not form a dense actin network at the leading edge, and consequently the rate of cell migration into an experimental wound was significantly reduced. In addition, BFA prevent ed an increase in pseudopodial activity and prevented the formation of long processes induced by phorbol 12-myristate 13-acetate. The effect s of BFA on cell shape and protrusional activity were quantitatively s imilar to those observed with the microtubule-disrupting agent nocodaz ole, although BFA had no effect on microtubule integrity. These result s suggest that the integrity of both the Golgi apparatus and microtubu les is necessary for the generation and maintenance of fibroblast asym metry, which is a prerequisite for directed cell migration.