Recycling endosomes associate with Golgi stacks in sea urchin embryos

Abstract

The trans-Golgi network (TGN) and recycling endosome (RE) have been recognized as sorting centers, the former for newly synthesized and the latter for endocytosed proteins. However, recent findings have revealed that TGN also receives endocytosed materials and RE accepts newly synthesized proteins destined to the plasma membrane. Recently, we reported that in both Drosophila and microtubule-disrupted HeLa cells, REs are associated with the trans-side of Golgi stacks. REs are highly dynamic: their separation from and association with Golgi stacks are often observed. Importantly, a newly synthesized cargo, glycosylphosphatidylinositol-anchored-GFP was found to be concentrated in Golgi-associated REs (GA-REs), while another cargo VSVG-GFP was excluded from GA-REs before post-Golgi trafficking to the plasma membrane. This suggested that the sorting of cargos takes place at the interface of Golgi stacks and GA-REs. In this study, we demonstrated that REs could associate with Golgi stacks in sea urchin embryos, further indicating that the association of REs with Golgi stacks is a well-conserved phenomenon in the animal kingdom.

Convergence of secretory, endosomal, and autophagic routes in trans-Golgi–associated lysosomes

“…Rab-GTPase regulators of endosomal traffic Rab4, Rab5, Rab7, and Rab11 frequently located there. Among these, Rab11 (recycling endosome) exhibited the highest degree of trans-Golgi association, consistent with recent studies showing that Rab11 foci attach to the trans-side of Golgi stacks in Drosophila , sea urchin, and human cells ( Fujii et al, 2020a ; Fujii et al, 2020b ). Similar to our observations of tGA-lysosomes in live blood cells, imaging in the Drosophila S2 cell line showed most trans-Golgi elements continuously accompanied by recycling endosomes that occasionally attached or detached ( Fujii et al, 2020a ).…”

RudLOV—a new optically synchronized cargo transport method reveals unexpected effect of dynasore

“…VSVG remained near the trans-Golgi cisternae and GA-RE until around 40 min (Figure 2F). This result is consistent with those of a previous study in which the RUSH system was used (Fujii et al, 2020a). Interestingly, TNFα appeared to force GA-RE away to create more space for it to remain in the gap (Figure 2H arrow) between the trans-Golgi cisternae and GA-RE after its exit from the trans-Golgi cisternae (Figure 2H, I).…”

“…We previously observed a relationship between the Golgi stacks and recycling endosomes (RE) in nocodazole-treated cells and described two types of REs: free RE and Golgi-associated RE (GA-RE). Most Golgi stacks are accompanied by GA-RE (Fujii et al, 2020a;Fujii et al, 2020b). Here, we refer to the Golgi stack/GA-RE complex as the Golgi/RE unit.…”

“…HeLa cells stably expressing GalT::iRFP713 (clone C9) (Fujii et al, 2020a) were transfected with pEBP-Sec61b-mTagBFP2-LOV2 using jetPRIME transfection reagent (Polyplus-transfection, Illkirch-Graffenstaden, France). After 24 h, the cells were selected using 2 µg/mL of puromycin (Fujifilm WAKO Chemicals, Osaka, Japan).…”