title: Acute depletion of plasma membrane phosphatidylinositol 4,5-bisphosphate impairs specific steps in endocytosis of the G-protein-coupled receptor.
abstract: Receptor endocytosis plays an important role in regulating the responsiveness of cells to specific ligands. Phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P(2)] has been shown to be crucial for endocytosis of some cell surface receptors, such as EGF and transferrin receptors, but its role in G-protein-coupled receptor internalization has not been investigated. By using luciferase-labeled type 1 angiotensin II (AT1R), type 2C serotonin (5HT2CR) or β(2) adrenergic (β2AR) receptors and fluorescently tagged proteins (β-arrestin-2, plasma-membrane-targeted Venus, Rab5) we were able to follow the sequence of molecular interactions along the endocytic route of the receptors in HEK293 cells using the highly sensitive method of bioluminescence resonance energy transfer and confocal microscopy. To study the role of plasma membrane PtdIns(4,5)P(2) in receptor endocytosis, we used our previously developed rapamycin-inducible heterodimerization system, in which the recruitment of a 5-phosphatase domain to the plasma membrane degrades PtdIns(4,5)P(2). Here we show that ligand-induced interaction of AT1, 5HT2C and β(2)A receptors with β-arrestin-2 was unaffected by PtdIns(4,5)P(2) depletion. However, trafficking of the receptors to Rab5-positive early endosomes was completely abolished in the absence of PtdIns(4,5)P(2). Remarkably, removal of the receptors from the plasma membrane was reduced but not eliminated after PtdIns(4,5)P(2) depletion. Under these conditions, stimulated AT1 receptors clustered along the plasma membrane, but did not enter the cells. Our data suggest that in the absence of PtdIns(4,5)P(2), these receptors move into clathrin-coated membrane structures, but these are not cleaved efficiently and hence cannot reach the early endosomal compartment.
authors.affiliation: Department of Physiology, Semmelweis University, Faculty of Medicine, Budapest, Hungary.
authors.forename: Dániel J
authors.initials: DJ
authors.lastname: Tóth
authors.forename: József T
authors.initials: JT
authors.lastname: Tóth
authors.forename: Gergö
authors.initials: G
authors.lastname: Gulyás
authors.forename: András
authors.initials: A
authors.lastname: Balla
authors.forename: Tamas
authors.initials: T
authors.lastname: Balla
authors.forename: László
authors.initials: L
authors.lastname: Hunyady
authors.forename: Péter
authors.initials: P
authors.lastname: Várnai
mesh_terms: D019390:Arrestins / Q000378:metabolism; D060807:Bioluminescence Resonance Energy Transfer Techniques; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D022163:Clathrin-Coated Vesicles / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects / Q000502:physiology*; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D017930:Genes, Reporter; D057809:HEK293 Cells; D006801:Humans; D008156:Luciferases; D018613:Microscopy, Confocal; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000172:deficiency*; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism*; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D044348:Receptors, Serotonin, 5-HT2 / Q000378:metabolism*; D020123:Sirolimus / Q000494:pharmacology; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins; D020696:rab5 GTP-Binding Proteins / Q000378:metabolism
chemical_list: C000605254:ARRB2 protein, human; D019390:Arrestins; D019269:Phosphatidylinositol 4,5-Diphosphate; D044140:Receptor, Angiotensin, Type 1; D018343:Receptors, Adrenergic, beta-2; D044348:Receptors, Serotonin, 5-HT2; D000071560:beta-Arrestin 2; D000071557:beta-Arrestins; D008156:Luciferases; D020696:rab5 GTP-Binding Proteins; D020123:Sirolimus