Abstract
Internalization of beta-adrenergic receptors (betaARs) occurs by the sequential binding of beta-arrestin, the clathrin adaptor AP-2, and clathrin. D-3 phosphoinositides, generated by the action of phosphoinositide 3-kinase (PI3K) may regulate the endocytic process; however, the precise molecular mechanism is unknown. Here we demonstrate that betaARKinase1 directly interacts with the PIK domain of PI3K to form a cytosolic complex. Overexpression of the PIK domain displaces endogenous PI3K from betaARK1 and prevents betaARK1-mediated translocation of PI3K to activated beta2ARs. Furthermore, disruption of the betaARK1/PI3K interaction inhibits agonist-stimulated AP-2 adaptor protein recruitment to the beta2AR and receptor endocytosis without affecting the internalization of other clathrin dependent processes such as internalization of the transferrin receptor. In contrast, AP-2 recruitment is enhanced in the presence of D-3 phospholipids, and receptor internalization is blocked in presence of the specific phosphatidylinositol-3,4,5-trisphosphate lipid phosphatase PTEN. These findings provide a molecular mechanism for the agonist-dependent recruitment of PI3K to betaARs, and support a role for the localized generation of D-3 phosphoinositides in regulating the recruitment of the receptor/cargo to clathrin-coated pits.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adaptor Protein Complex delta Subunits
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Adaptor Proteins, Vesicular Transport
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Adrenergic beta-2 Receptor Agonists
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Adrenergic beta-Agonists / pharmacology
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Arrestins / metabolism*
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Carrier Proteins / metabolism*
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Cell Membrane / enzymology*
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Cell Membrane / ultrastructure
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Cells, Cultured
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Clathrin / metabolism
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Cyclic AMP-Dependent Protein Kinases / genetics
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Cyclic AMP-Dependent Protein Kinases / metabolism
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Endocytosis / physiology*
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Eukaryotic Cells / enzymology*
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Eukaryotic Cells / ultrastructure
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Gene Expression / physiology
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Humans
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Isoproterenol / pharmacology
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Membrane Proteins / metabolism*
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PTEN Phosphohydrolase
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Phosphatidylinositol 3-Kinases / metabolism*
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Phosphatidylinositol Phosphates / antagonists & inhibitors
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Phosphatidylinositol Phosphates / biosynthesis
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Phosphoric Monoester Hydrolases / genetics
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Phosphoric Monoester Hydrolases / metabolism
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Protein Structure, Tertiary / genetics
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Protein Transport / physiology
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Receptors, Adrenergic, beta-2 / metabolism*
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Signal Transduction / physiology
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Transfection
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Transferrin / metabolism
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Tumor Suppressor Proteins / genetics
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Tumor Suppressor Proteins / metabolism
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beta-Adrenergic Receptor Kinases
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beta-Arrestins
Substances
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Adaptor Protein Complex delta Subunits
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Adaptor Proteins, Vesicular Transport
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Adrenergic beta-2 Receptor Agonists
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Adrenergic beta-Agonists
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Arrestins
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Carrier Proteins
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Clathrin
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Membrane Proteins
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Phosphatidylinositol Phosphates
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Receptors, Adrenergic, beta-2
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Transferrin
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Tumor Suppressor Proteins
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beta-Arrestins
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phosphatidylinositol 3,4,5-triphosphate
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Phosphatidylinositol 3-Kinases
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Cyclic AMP-Dependent Protein Kinases
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beta-Adrenergic Receptor Kinases
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Phosphoric Monoester Hydrolases
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PTEN Phosphohydrolase
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PTEN protein, human
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Isoproterenol