title: Anchoring of both PKA and 14-3-3 inhibits the Rho-GEF activity of the AKAP-Lbc signaling complex.
abstract: A-kinase anchoring proteins (AKAPs) target the cAMP-regulated protein kinase (PKA) to its physiological substrates. We recently identified a novel anchoring protein, called AKAP-Lbc, which functions as a PKA-targeting protein as well as a guanine nucleotide exchange factor (GEF) for RhoA. We demonstrated that AKAP-Lbc Rho-GEF activity is stimulated by the alpha subunit of the heterotrimeric G protein G12. Here, we identified 14-3-3 as a novel regulatory protein interacting with AKAP-Lbc. Elevation of the cellular concentration of cAMP activates the PKA holoenzyme anchored to AKAP-Lbc, which phosphorylates the anchoring protein on the serine 1565. This phosphorylation event induces the recruitment of 14-3-3, which inhibits the Rho-GEF activity of AKAP-Lbc. AKAP-Lbc mutants that fail to interact with PKA or with 14-3-3 show a higher basal Rho-GEF activity as compared to the wild-type protein. This suggests that, under basal conditions, 14-3-3 maintains AKAP-Lbc in an inactive state. Therefore, while it is known that AKAP-Lbc activity can be stimulated by Galpha12, in this study we demonstrated that it is inhibited by the anchoring of both PKA and 14-3-3.
authors.affiliation: Département de Pharmacologie et de Toxicologie, Faculté de Médecine, Lausanne, Switzerland. Dario.diviani@ipharm.unil.ch
authors.forename: Dario
authors.initials: D
authors.lastname: Diviani
authors.forename: Liliane
authors.initials: L
authors.lastname: Abuin
authors.forename: Susanna
authors.initials: S
authors.lastname: Cotecchia
authors.forename: Laetitia
authors.initials: L
authors.lastname: Pansier
mesh_terms: D054758:A Kinase Anchor Proteins; D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004789:Enzyme Activation; D005982:Glutathione Transferase / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D006801:Humans; D015778:Minor Histocompatibility Antigens; D008956:Models, Chemical; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017354:Point Mutation; D040081:Protein Array Analysis; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012694:Serine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D054758:A Kinase Anchor Proteins; C085467:AKAP13 protein, human; D048868:Adaptor Proteins, Signal Transducing; D020662:Guanine Nucleotide Exchange Factors; D015778:Minor Histocompatibility Antigens; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D012694:Serine; D005982:Glutathione Transferase; D017868:Cyclic AMP-Dependent Protein Kinases