Reversible control of post-Golgi transport by brefeldin A reveals recycling endosome maturation during glycosylphosphatidylinositol-anchored protein transport.

Post-Golgi transport plays a crucial role in establishing and maintaining cellular function; however, its mechanism of action remains unclear. Therefore, a system to manipulate post-Golgi transport is highly desirable. In this study, we developed a brefeldin A (BFA)-controlled system to block and restart post-Golgi transport freely, allowing the detailed observation of cargo exit from Golgi stacks using live-cell imaging, electron microscopy, and biochemical analysis. Using this system, glycosylphosphatidylinositol-anchored protein (GPI-AP) transport from the trans-Golgi network (TGN) to Golgi-associated recycling endosomes (GA-REs) was visualized. GA-REs expanded during GPI-AP uptake, indicating maturation from the TGN into REs, which later detached as free REs released from the Golgi stacks. Tubular and pearled GPI-AP-positive structures formed on the TGN, which were likely GA-REs transporting GPI-AP from the TGN. REs matured in AP-1-deficient cells, whereas GA-RE detachment was impaired, and long-tubules were observed, thereby delaying GPI-AP delivery to the plasma membrane.