Abstract
The conditional use of actin during clathrin-mediated endocytosis in mammalian cells suggests that the cell controls whether and how actin is used. Using a combination of biochemical reconstitution and mammalian cell culture, we elucidate a mechanism by which the coincidence of PI(4,5)P2 and PI(3)P in a curved vesicle triggers actin polymerization. At clathrin-coated pits, PI(3)P is produced by the INPP4A hydrolysis of PI(3,4)P2, and this is necessary for actin-driven endocytosis. Both Cdc42⋅guanosine triphosphate and SNX9 activate N-WASP-WIP- and Arp2/3-mediated actin nucleation. Membrane curvature, PI(4,5)P2, and PI(3)P signals are needed for SNX9 assembly via its PX-BAR domain, whereas signaling through Cdc42 is activated by PI(4,5)P2 alone. INPP4A activity is stimulated by high membrane curvature and synergizes with SNX9 BAR domain binding in a process we call curvature cascade amplification. We show that the SNX9-driven actin comets that arise on human disease-associated oculocerebrorenal syndrome of Lowe (OCRL) deficiencies are reduced by inhibiting PI(3)P production, suggesting PI(3)P kinase inhibitors as a therapeutic strategy in Lowe syndrome.
© 2017 Daste et al.
Publication types
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Video-Audio Media
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Research Support, Non-U.S. Gov't
MeSH terms
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Actin-Related Protein 2-3 Complex / genetics
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Actin-Related Protein 2-3 Complex / metabolism
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Actins / metabolism*
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Animals
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CRISPR-Cas Systems
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Clathrin / metabolism*
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Clathrin-Coated Vesicles / metabolism*
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Coated Pits, Cell-Membrane / metabolism*
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Cytoskeletal Proteins / genetics
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Cytoskeletal Proteins / metabolism
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Endocytosis*
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HeLa Cells
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Humans
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Hydrolysis
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Intracellular Signaling Peptides and Proteins / genetics
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Intracellular Signaling Peptides and Proteins / metabolism
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Oculocerebrorenal Syndrome / genetics
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Oculocerebrorenal Syndrome / metabolism
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Phosphatidylinositol 4,5-Diphosphate / metabolism
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Phosphatidylinositol Phosphates / metabolism
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Phosphatidylinositols / metabolism*
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Phosphoric Monoester Hydrolases / genetics
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Phosphoric Monoester Hydrolases / metabolism
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Protein Multimerization
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RNA Interference
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Retinal Pigment Epithelium / metabolism
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Signal Transduction
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Sorting Nexins / genetics
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Sorting Nexins / metabolism
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Time Factors
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Transfection
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Wiskott-Aldrich Syndrome Protein, Neuronal / genetics
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Wiskott-Aldrich Syndrome Protein, Neuronal / metabolism
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Xenopus laevis
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cdc42 GTP-Binding Protein / genetics
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cdc42 GTP-Binding Protein / metabolism
Substances
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Actin-Related Protein 2-3 Complex
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Actins
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Clathrin
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Cytoskeletal Proteins
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Intracellular Signaling Peptides and Proteins
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Phosphatidylinositol 4,5-Diphosphate
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Phosphatidylinositol Phosphates
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Phosphatidylinositols
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SNX9 protein, human
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Sorting Nexins
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WASL protein, human
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WIPF1 protein, human
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Wiskott-Aldrich Syndrome Protein, Neuronal
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phosphatidylinositol 3-phosphate
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phosphoinositide-3,4-bisphosphate
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Phosphoric Monoester Hydrolases
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phosphatidylinositol-3,4-bisphosphate 4-phosphatase
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cdc42 GTP-Binding Protein
Associated data
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PDB/2RAI
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GENBANK/NM_030266