Abstract
Endocytosis of glycosylphosphatidyl inositol (GPI)-anchored proteins (GPI-APs) and the fluid phase takes place primarily through a dynamin- and clathrin-independent, Cdc42-regulated pinocytic mechanism. This mechanism is mediated by primary carriers called clathrin-independent carriers (CLICs), which fuse to form tubular early endocytic compartments called GPI-AP enriched endosomal compartments (GEECs). Here, we show that reduction in activity or levels of ARF1 specifically inhibits GPI-AP and fluid-phase endocytosis without affecting other clathrin-dependent or independent endocytic pathways. ARF1 is activated at distinct sites on the plasma membrane, and by the recruitment of RhoGAP domain-containing protein, ARHGAP10, to the plasma membrane, modulates cell-surface Cdc42 dynamics. This results in the coupling of ARF1 and Cdc42 activity to regulate endocytosis at the plasma membrane. These findings provide a molecular basis for a crosstalk of endocytosis with secretion by the sharing of a key regulator of secretory traffic, ARF1.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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ADP-Ribosylation Factor 1 / genetics
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ADP-Ribosylation Factor 1 / metabolism*
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Animals
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Blotting, Western
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Brefeldin A / pharmacology
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CHO Cells
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Caveolins / metabolism
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Cell Membrane / drug effects
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Cell Membrane / metabolism
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Clathrin / metabolism
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Clathrin-Coated Vesicles / metabolism
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Cricetinae
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Cricetulus
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Dynamins / metabolism*
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Endocytosis / drug effects
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Endocytosis / physiology*
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GTPase-Activating Proteins / metabolism
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Glycosylphosphatidylinositols / metabolism
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Green Fluorescent Proteins / genetics
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Green Fluorescent Proteins / metabolism
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Membrane Proteins / metabolism
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Microscopy, Confocal
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Microscopy, Fluorescence
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RNA, Small Interfering / genetics
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Transfection
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cdc42 GTP-Binding Protein / metabolism
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rhoA GTP-Binding Protein / metabolism
Substances
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Caveolins
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Clathrin
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GTPase-Activating Proteins
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Glycosylphosphatidylinositols
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Membrane Proteins
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RNA, Small Interfering
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Green Fluorescent Proteins
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Brefeldin A
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ADP-Ribosylation Factor 1
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cdc42 GTP-Binding Protein
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rhoA GTP-Binding Protein
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Dynamins