Abstract
Influenza virus particles are assembled at the plasma membrane in concert with incorporation of the virus genome, but the details of its spatio-temporal regulation are not understood. Here we showed that influenza virus infection induces the assembly of pericentrosomal endocytic recycling compartment (ERC) through the activation of Rab11a GTPase and cell cycle-independent maturation of centrosome by YB-1, a multifunctional protein that is involved in mitotic division, RNA metabolism and tumorigenesis. YB-1 is recruited to the centrosome in infected cells and is required for anchoring microtubules to the centrosome. We also found that viral infection accumulates cholesterol in ERC and is dependent on YB-1. Depletion of YB-1 shows reduced cholesterol-enriched ERC and prevented budozone formation at the plasma membrane. These results suggest that cholesterol in recycling endosomes, which are emanated from ERC, may trigger the virus assembly concomitantly with the packaging of the virus genome. We propose that the virus genome is transported to the plasma membrane by cholesterol-enriched recycling endosomes through cell cycle-independent activation of the centrosome by YB-1.
Highlights
Endocytic transport pathways are important to arrange the plasma membrane components for diversified cellular processes at the plasma membrane including virus budding
Influenza virus particles are assembled at the plasma membrane in concert with incorporation of the virus genome, but the details of its spatiotemporal regulation are unknown
We found that the virus genome is transported to the plasma membrane using cholesterol-enriched recycling endosomes through cell cycle-independent activation of the centrosome by recruiting Y-box binding protein-1 (YB-1), which is a mitotic centrosomal protein
Summary
Endocytic transport pathways are important to arrange the plasma membrane components for diversified cellular processes at the plasma membrane including virus budding. Endocytosed proteins are first delivered to the early/sorting endosomes, from where proteins are either recycled back to the plasma membrane or transported to late endosomes and lysosomes. Rab small GTPase family members show distinct intracellular localization and function as molecular switches to regulate vesicle carrier formation and fusion with target membranes. Rab11a-positive recycling endosomes are crucial for recycling and delivery of plasma membrane components to the cell surface [1,2,3]. The Rab11a-positive transport vesicles emerge from specific organelles called endocytic recycling compartments (ERC). ERCs constitute a collection of tubular organelles that are close to the nucleus and associated with the microtubule organizing centre (MTOC). The functional significance of ERCs is not fully understood
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