Figure 6. PBA stimulates trafficking out of the intracellular organelles.

NAG cells were untreated, or treated with thapsigargin (0.25 µM), tunicamycin (5 µg/ml), or brefeldin A (5 µg/ml) in the presence or absence of PBA for 24 hours. The cells were stained with the VP16 antibody (red) and counterstained with Hoescht (blue) to localize the nuclei. Confocal imaging was performed to examine protein localization. In untreated cells, APPGV16 localized throughout the cytosol with slight peri-nuclear aggregations observed, consistent with the ER localization of de novo membrane proteins. PBA treatment promoted migration of APPGV16 toward the plasma membrane (top row). In tunicamycin, thapsigargin and brefeldin A treated cells, APPGV16 localized to the ER-like perinuclear region (left column, lower three images). Upon the addition of 1 mM or 5 mM PBA, APPGV16 localization shifted away from the nucleus in tunicamycin and thapsigargin treated NAG cells. In contrast, PBA had no effect upon the localization of APPGV16 in the brefeldin A treated cells.