Golgi Cisternal Unstacking Stimulates COPI Vesicle Budding and Protein Transport

Abstract

The Golgi apparatus in mammalian cells is composed of flattened cisternae that are densely packed to form stacks. We have used the Golgi stacking protein GRASP65 as a tool to modify the stacking state of Golgi cisternae. We established an assay to measure protein transport to the cell surface in post-mitotic cells in which the Golgi was unstacked. Cells with an unstacked Golgi showed a higher transport rate compared to cells with stacked Golgi membranes. Vesicle budding from unstacked cisternae in vitro was significantly increased compared to stacked membranes. These results suggest that Golgi cisternal stacking can directly regulate vesicle formation and thus the rate of protein transport through the Golgi. The results further suggest that at the onset of mitosis, unstacking of cisternae allows extensive and rapid vesiculation of the Golgi in preparation for its subsequent partitioning.

Aβ-induced Golgi fragmentation in Alzheimer’s disease enhances Aβ production

“…S8, rescue of the Golgi structure by GRASP65 expression reduced VSV-G trafficking at different time points of release. This result is consistent with our previous finding that disruption of Golgi enhances protein trafficking (14,15), in contract to the disruption of GM130 function, which slows trafficking (17).…”

“…CIP is a 126-aa peptide containing p35 , which blocks cdk5 interaction with its activator p25, thereby specifically inhibiting cdk5. The CIP is fused to an 11-aa HIV TAT sequence (TAT-CIP) for better temporal and dosage control when applied to cells (14). TAT-GFP served as a control.…”

“…More importantly, how Golgi fragmentation affects APP trafficking and Aβ production is unknown. Our previous studies found that Golgi fragmentation enhances vesicle budding from the Golgi membranes and accelerates protein trafficking (14,15). Thus, fragmentation of the Golgi observed in AD may accelerate APP trafficking and increase Aβ production.…”

Golgi-associated GSK3β regulates the sorting process of post-Golgi membrane trafficking

“…In addition, Miller and co-workers have reported that CLASPdependent Golgi-derived microtubules are required for Golgi organization and polarized membrane trafficking (Miller et al, 2009). Furthermore, Wang and colleagues have reported that unstacking of the Golgi facilitates the post-Golgi transport of CD8 to the cell surface (Wang et al, 2008). Our results might support a possible mechanistic model in which Golgi-derived CLASP-dependent microtubules, which are regulated by GSK3 phosphorylation, control the organization of the Golgi and are involved in the sorting of cargo at the TGN.…”

Mitotic regulation of SREBP and ATF6 by separation of the Golgi and ER

“…36,38 Unstacking exposes more surface area of the cisternae from which COPI vesicles can bud more efficiently and therefore contributes to the rapid disassembly of the Golgi during mitosis. 39 In telophase, the Golgi clusters merge and reform a new Golgi ribbon in each daughter cell. 40 …”