Microtubule-independent secretion requires functional maturation of Golgi elements

Abstract

The Golgi complex is responsible for processing and sorting of secretory cargos. Microtubules are known to accelerate the transport of proteins from the endoplasmic reticulum (ER) to the Golgi complex and from the Golgi to the plasma membrane. However, whether postGolgi transport strictly requires microtubules is still unclear. Using the retention using selective hooks (RUSH) system to synchronize the trafficking of cargos, we show that anterograde transport of tumor necrosis factor (TNF) is strongly reduced without microtubules. We show that two populations of Golgi elements co-exist in these cells. A centrally located and giantin-positive Golgi complex that sustains trafficking, and newly formed peripheral Golgi mini-stacks that accumulate cargos in cells without microtubules. Using a genomeedited GFP-giantin cell line, we observe that the trafficking-competent Golgi population corresponds to the pre-existing population that was present before removal of microtubules. All Golgi elements support trafficking after long-term depletion of microtubules and after relocation of Golgi proteins to the ER after treatment with Brefeldin A. Our results demonstrate that functional maturation of Golgi elements is needed to ensure post-Golgi trafficking, and that microtubule-driven post-Golgi transport is not strictly required.

Nicotine exposure and neuronal activity regulate Golgi membrane dispersal and distribution

“…Here, Halo-tagged St3 (St3-Halo; red) and GFP-GM130 (green) were transfected to permit live-imaging of the Golgi membranes. St3-Halo and GFP-GM130 fluorescence overlapped on the same structure but with an offset (see merged bottom images), consistent with a cis/trans polarized Golgi structure, or "ministack", as observed with Golgi dispersal after Nocodazole treatment (Fourriere, Divoux et al 2016). In the time lapse shown in Fig.…”

“…As seen with nocodazole-induced dispersal of the GA (Fourriere, Divoux et al 2016), we find that the dispersed membranes induced by nicotine are functional ( Fig. 5D) and that the dispersal itself is reversible .…”

“…This rate is slower than that of nicotine-induced dispersal, which occurs ~2 to 4 hours after nicotine exposure (Supplemental Figs. S5-2A and S5-2B; top), and is somewhat slower than the rate of dispersal resulting from nocadozole treatment (Fourriere, Divoux et al 2016). The rates at which dispersal by nicotine occur were similar to the rate of nicotine upregulation of a4b2Rs for the fast phase of the upregulation (Govind, Walsh et al 2012), suggesting that Golgi dispersal with nicotine exposure occurs in parallel with receptor upregulation.…”

Golgi ribbon disassembly during mitosis, differentiation and disease progression

“…The interconnection of stacks is not strictly required for the secretory function of the Golgi, since disrupting the ribbon into discrete mini-stacks by microtubule depolymerization does not prevent cargo trafficking to the cell surface. However, transport kinetics is reduced in the initial phase but resumed to normal level at later stages [8], indicating that mini-stacks need to be fully dispersed and matured to become transport-competent [9]. …”

Meeting after meeting: 20 years of discoveries by the members of the Exocytosis–Endocytosis Club

“…A major consequence of this work was the understanding that multiple secretion pathways correspond to various specific cargoes (Boncompain and Perez, ). This insight allowed the Perez team to precisely determine the role of microtubules in the secretory pathway from the ER to the plasma membrane, linking to functional maturation of the Golgi, and highlighting the existence of two pools of Golgi in cells (Fourriere et al., ). The functional maturation of Golgi complexes and the existence of two Golgi pools were proposed earlier by F. Perez team (Jollivet et al., ; Nizak et al., ).…”