title: Regulation of G protein-coupled receptor activities by the platelet-endothelial cell adhesion molecule, PECAM-1.
abstract: It is becoming increasingly evident that the cell-cell junction is a major signaling center. Here we show that the Galphaq/11 subunit of heterotrimeric G proteins forms a complex with platelet-endothelial cell adhesion molecule 1 (PECAM-1), a junctional protein that has been shown to be involved in mechanosignaling in endothelial cells. To understand the role of PECAM-1 in this complex, we determined the critical regions of PECAM-1 involved in this interaction. By expressing truncated forms of PECAM-1 in human embryonic kidney (HEK293) cells, we found that the cytoplasmic domain of PECAM-1 is not required for its association with Galphaq/11. Domain swapping of PECAM-1 with intracellular cell adhesion molecule 1 (ICAM-1), a protein that does not form a complex with Galphaq/11, provides evidence that the extracellular domain of PECAM-1 is critical for this interaction. This result also suggests that PECAM-1 does not directly interact with Galphaq/11. Coexpression of bradykinin receptor B2 (BKRB2), a Galphaq/11-coupled receptor, with PECAM-1 enhances formation of the PECAM-1-Galphaq/11 complex, suggesting an interaction between PECAM-1 and BKRB2. Co-immunoprecipitation experiments indicate that these two molecules indeed form a complex when expressed in HEK293 cells. Activation of ERK1/2 by bradykinin in HUVEC is enhanced when PECAM-1 expression is inhibited by transfection of small interference RNA against PECAM-1. Taken together, our results provide evidence of interaction of PECAM-1 with BKRB2 and of its possible role in regulating G protein-coupled receptor (GPCR) and G protein functions.
authors.affiliation: La Jolla Bioengineering Institute, 505 Coast Boulevard South, Suite 406, La Jolla, California 92037, USA.
authors.forename: Jiunn-chern
authors.initials: JC
authors.lastname: Yeh
authors.forename: Laura A
authors.initials: LA
authors.lastname: Otte
authors.forename: John A
authors.initials: JA
authors.lastname: Frangos
mesh_terms: D017607:Aluminum Compounds / Q000494:pharmacology; D001665:Binding Sites / Q000235:genetics; D001920:Bradykinin / Q000494:pharmacology; D002460:Cell Line; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D005459:Fluorides / Q000494:pharmacology; D043802:GTP-Binding Protein alpha Subunits, Gq-G11 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009154:Mutation; D009997:Osmotic Pressure; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D034741:RNA, Small Interfering / Q000235:genetics; D043782:Receptor, Bradykinin B2 / Q000235:genetics / Q000378:metabolism; D014162:Transfection
chemical_list: D017607:Aluminum Compounds; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D034741:RNA, Small Interfering; D043782:Receptor, Bradykinin B2; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D043802:GTP-Binding Protein alpha Subunits, Gq-G11; D005459:Fluorides; D001920:Bradykinin; C032311:aluminum fluoride