title: Constitutive and growth factor-regulated phosphorylation of caveolin-1 occurs at the same site (Tyr-14) in vivo: identification of a c-Src/Cav-1/Grb7 signaling cassette.
abstract: Caveolin-1 was first identified as a phosphoprotein in Rous sarcoma virus (RSV)-transformed chicken embryo fibroblasts. Tyrosine 14 is now thought to be the principal site for recognition by c-Src kinase; however, little is known about this phosphorylation event. Here, we generated a monoclonal antibody (mAb) probe that recognizes only tyrosine 14-phosphorylated caveolin-1. Using this approach, we show that caveolin-1 (Y14) is a specific tyrosine kinase substrate that is constitutively phosphorylated in Src- and Abl-transformed cells and transiently phosphorylated in a regulated fashion during growth factor signaling. We also provide evidence that tyrosine-phosphorylated caveolin-1 is localized at the major sites of tyrosine-kinase signaling, i.e. focal adhesions. By analogy with other signaling events, we hypothesized that caveolin-1 could serve as a docking site for pTyr-binding molecules. In support of this hypothesis, we show that phosphorylation of caveolin-1 on tyrosine 14 confers binding to Grb7 (an SH2-domain containing protein) both in vitro and in vivo. Furthermore, we demonstrate that binding of Grb7 to tyrosine 14-phosphorylated caveolin-1 functionally augments anchorage-independent growth and epidermal growth factor (EGF)-stimulated cell migration. We discuss the possible implications of our findings in the context of signal transduction.
authors.affiliation: Department of Molecular Pharmacology and The Albert Einstein Cancer Center, Albert Einstein College of Medicine, Bronx, New York 10461, USA.
authors.forename: H
authors.initials: H
authors.lastname: Lee
authors.forename: D
authors.initials: D
authors.lastname: Volonte
authors.forename: F
authors.initials: F
authors.lastname: Galbiati
authors.forename: P
authors.initials: P
authors.lastname: Iyengar
authors.forename: D M
authors.initials: DM
authors.lastname: Lublin
authors.forename: D B
authors.initials: DB
authors.lastname: Bregman
authors.forename: M T
authors.initials: MT
authors.lastname: Wilson
authors.forename: R
authors.initials: R
authors.lastname: Campos-Gonzalez
authors.forename: B
authors.initials: B
authors.lastname: Bouzahzah
authors.forename: R G
authors.initials: RG
authors.lastname: Pestell
authors.forename: P E
authors.initials: PE
authors.lastname: Scherer
authors.forename: M P
authors.initials: MP
authors.lastname: Lisanti
mesh_terms: D016475:3T3 Cells; D017667:Adipocytes / Q000187:drug effects; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000494:pharmacology; D021941:Caveolae / Q000378:metabolism; D051242:Caveolin 1; D022461:Caveolins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002465:Cell Movement / Q000502:physiology; D004815:Epidermal Growth Factor / Q000494:pharmacology; D066246:ErbB Receptors / Q000378:metabolism; D005260:Female; D051382:GRB7 Adaptor Protein; D006133:Growth Substances / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000378:metabolism / Q000494:pharmacology; D050356:Lipid Metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010766:Phosphorylation / Q000187:drug effects; D011506:Proteins / Q000378:metabolism*; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism*; D014638:Vanadates / Q000494:pharmacology; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; C495540:CAV1 protein, human; C495541:Cav1 protein, mouse; D051242:Caveolin 1; D022461:Caveolins; C495955:GRB7 protein, human; C495956:Grb7 protein, mouse; D006133:Growth Substances; D007328:Insulin; D011506:Proteins; D051382:GRB7 Adaptor Protein; D014638:Vanadates; D014443:Tyrosine; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D019061:src-Family Kinases