VAMP-associated protein-A and oxysterol-binding protein–related protein 3 promote the entry of late endosomes into the nucleoplasmic reticulum

Abstract

The endocytic pathway plays an instrumental role in recycling internalized molecules back to the plasma membrane or in directing them to lysosomes for degradation. We recently reported a new role of endosomes-the delivery of components from extracellular vesicles (EVs) to the nucleoplasm of recipient cells. Using indirect immunofluorescence, FRET, immunoisolation techniques, and RNAi, we report here a tripartite protein complex (referred to as the VOR complex) that is essential for the nuclear transfer of EV-derived components by orchestrating the specific localization of late endosomes into nucleoplasmic reticulum. We found that the VOR complex contains the endoplasmic reticulum-localized vesicle-associated membrane protein (VAMP)-associated protein A (VAP-A), the cytoplasmic oxysterol-binding protein-related protein 3 (ORP3), and late endosome-associated small GTPase Rab7. The silencing of VAP-A or ORP3 abrogated the association of Rab7-positive late endosomes with nuclear envelope invaginations and, hence, the transport of endocytosed EV-derived components to the nucleoplasm of recipient cells. We conclude that the VOR complex can be targeted to inhibit EV-mediated intercellular communication, which can have therapeutic potential for managing cancer in which the release of EVs is dysregulated.

Prominin‐1 controls stem cell activation by orchestrating ciliary dynamics

“…First, our data with importazole treatment suggest that nuclear pores are involved in this process instead of the nuclear entrapment following the reorganization of the nuclear envelope during mitosis. Second, novel intracellular routes involving endosomal pathways were recently described to explain the nuclear localization of surface proteins (Chaumet et al , ; Santos et al , ). One of them relies on the presence of late endosomes in the nucleoplasmic reticulum where the endocytosed membrane proteins including Prom1 are delivered on the way to the nucleoplasm through the nuclear pores (Santos et al , ).…”

“…Second, novel intracellular routes involving endosomal pathways were recently described to explain the nuclear localization of surface proteins (Chaumet et al , ; Santos et al , ). One of them relies on the presence of late endosomes in the nucleoplasmic reticulum where the endocytosed membrane proteins including Prom1 are delivered on the way to the nucleoplasm through the nuclear pores (Santos et al , ). In these processes, both ubiquitination and the interaction with adaptor protein syntenin‐1 can regulate the intracellular trafficking of Prom1 (Karbanová et al , ; Yang et al , ).…”

Selective EMC subunits act as molecular tethers of intracellular organelles exploited during viral entry

“…To validate this split-GFP assay as a bonafide strategy for assessing ER-LE contact, we depleted the ER membrane protein VAPA/B and found that the GFP signal was indeed decreased ( Supplementary Fig. 5); VAPA/ B were previously shown to be ER-LE tethering proteins [32][33][34] . Strikingly, depletion of EMC4 and EMC7 also decreased the GFP intensity ( Fig.…”

TheDrosophilaEGFR ligand mSpitz is delivered to cytoplasmic capes at sites of non-canonical RNA export on the nuclear envelopeviathe endosomal system

“…While investigating the role of spectrin in endosomal transport in Drosophila we discovered that mSpitz, the membrane bound precursor of the EGF Receptor ligand sSpitz, strongly Floyd Mattie et al p4 accumulates in nuclear envelope invaginations 19 . These structures, called cytoplasmic capes 20 , were originally seen in ultrastructural studies of Drosophila salivary gland nuclei 21 and are distinguished from the nuclear reticulum in scale and morphology 22,23 . We previously demonstrated that these distinctive structures are strongly associate with endosome-like organelles and contain ubiquitylated proteins 19 .…”