Abstract
The recruitment of the small GTPase Arf6 and ARNO from cytosol to endosomal membranes is driven by V-ATPase-dependent intra-endosomal acidification. The molecular mechanism that mediates this pH-sensitive recruitment and its role are unknown. Here, we demonstrate that Arf6 interacts with the c-subunit, and ARNO with the a2-isoform of V-ATPase. The a2-isoform is targeted to early endosomes, interacts with ARNO in an intra-endosomal acidification-dependent manner, and disruption of this interaction results in reversible inhibition of endocytosis. Inhibition of endosomal acidification abrogates protein trafficking between early and late endosomal compartments. These data demonstrate the crucial role of early endosomal acidification and V-ATPase/ARNO/Arf6 interactions in the regulation of the endocytic degradative pathway. They also indicate that V-ATPase could modulate membrane trafficking by recruiting and interacting with ARNO and Arf6; characteristics that are consistent with the role of V-ATPase as an essential component of the endosomal pH-sensing machinery.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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ADP-Ribosylation Factor 6
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ADP-Ribosylation Factors / metabolism*
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Ammonium Chloride / pharmacology
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Animals
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Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone / pharmacology
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Cell Line
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Dynamins / genetics
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Dynamins / metabolism
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Endocytosis / drug effects
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Endocytosis / physiology
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Endosomes / drug effects
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Endosomes / metabolism*
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Epithelial Cells / metabolism
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GTPase-Activating Proteins / genetics
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GTPase-Activating Proteins / metabolism*
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Green Fluorescent Proteins / genetics
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Green Fluorescent Proteins / metabolism
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HeLa Cells
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Humans
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Hydrogen-Ion Concentration / drug effects
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Isoenzymes / genetics
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Isoenzymes / metabolism
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Kidney Tubules, Proximal / cytology
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Kidney Tubules, Proximal / metabolism
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Macrolides / pharmacology
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Mice
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Models, Biological
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Mutation / genetics
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Protein Binding
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Protein Interaction Mapping
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Protein Transport / physiology
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Proteins / metabolism*
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Serum Albumin, Bovine / metabolism
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Transfection
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Vacuolar Proton-Translocating ATPases / antagonists & inhibitors
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Vacuolar Proton-Translocating ATPases / genetics
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Vacuolar Proton-Translocating ATPases / metabolism*
Substances
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ADP-Ribosylation Factor 6
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GTPase-Activating Proteins
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Isoenzymes
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Macrolides
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Proteins
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cytohesin-2
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Ammonium Chloride
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bafilomycin A
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Green Fluorescent Proteins
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Serum Albumin, Bovine
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Carbonyl Cyanide p-Trifluoromethoxyphenylhydrazone
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Vacuolar Proton-Translocating ATPases
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ADP-Ribosylation Factors
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ARF6 protein, human
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Arf6 protein, mouse
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Dynamins