Extracellular membrane particles en route to the nucleus - exploring the VOR complex.

Abstract

Intercellular communication is an essential hallmark of multicellular organisms for their development and adult tissue homeostasis. Over the past two decades, attention has been focused on communication mechanisms based on various membrane structures, as illustrated by the burst of scientific literature in the field of extracellular vesicles (EVs). These lipid bilayer-bound nano- or microparticles, as vehicle-like devices, act as regulators in various biological and physiological processes. When EVs are internalized by recipient cells, their membrane and cytoplasmic cargoes can interfere with cellular activities, affecting pathways that regulate cell proliferation, differentiation, and migration. In cancer, EVs can transfer oncogenic factors, stimulate neo-angiogenesis and immunosuppression, reprogram stromal cells, and confer drug resistance traits, thereby remodeling the surrounding microenvironment. Although the mechanisms underlying EV biogenesis and uptake are now better understood, little is known about the spatiotemporal mechanism(s) of their actions after internalization. In this respect, we have shown that a fraction of endocytosed EVs reaches the nuclear compartment via the VOR (VAP-A-ORP3-Rab7) complex-mediated docking of late endosomes to the outer nuclear membrane in the nucleoplasmic reticulum, positioning and facilitating the transfer of EV cargoes into the nucleoplasm via nuclear pores. Here, we highlight the EV heterogeneity, the cellular pathways governing EV release and uptake by donor and recipient cells, respectively, and focus on a novel intracellular pathway leading to the nuclear transfer of EV cargoes. We will discuss how to intercept it, which could open up new avenues for clinical applications in which EVs and other small extracellular particles (e.g., retroviruses) are implicated.