title: Cross talk between phosphatidylinositol 3-kinase and cyclic AMP (cAMP)-protein kinase a signaling pathways at the level of a protein kinase B/beta-arrestin/cAMP phosphodiesterase 4 complex.
abstract: Engagement of the T-cell receptor (TCR) in human primary T cells activates a cyclic AMP (cAMP)-protein kinase A (PKA)-Csk inhibitory pathway that prevents full T-cell activation in the absence of a coreceptor stimulus. Here, we demonstrate that stimulation of CD28 leads to recruitment to lipid rafts of a beta-arrestin/phosphodiesterase 4 (PDE4) complex that serves to degrade cAMP locally. Redistribution of the complex from the cytosol depends on Lck and phosphatidylinositol 3-kinase (PI3K) activity. Protein kinase B (PKB) interacts directly with beta-arrestin to form part of the supramolecular complex together with sequestered PDE4. Translocation is mediated by the PKB plextrin homology (PH) domain, thus revealing a new role for PKB as an adaptor coupling PI3K and cAMP signaling. Functionally, PI3K activation and phosphatidylinositol-(3,4,5)-triphosphate (PIP3) production, leading to recruitment of the supramolecular PKB/beta-arrestin/PDE4 complex to the membrane via the PKB PH domain, results in degradation of the TCR-induced cAMP pool located in lipid rafts, thereby allowing full T-cell activation to proceed.
authors.affiliation: Biotechnology Centre of Oslo, University of Oslo, P.O. Box 1125, N-0317 Oslo, Norway.
authors.forename: Elisa
authors.initials: E
authors.lastname: Bjørgo
authors.forename: Silje A
authors.initials: SA
authors.lastname: Solheim
authors.forename: Hilde
authors.initials: H
authors.lastname: Abrahamsen
authors.forename: George S
authors.initials: GS
authors.lastname: Baillie
authors.forename: Kim M
authors.initials: KM
authors.lastname: Brown
authors.forename: Torunn
authors.initials: T
authors.lastname: Berge
authors.forename: Klaus
authors.initials: K
authors.lastname: Okkenhaug
authors.forename: Miles D
authors.initials: MD
authors.lastname: Houslay
authors.forename: Kjetil
authors.initials: K
authors.lastname: Taskén
mesh_terms: D000595:Amino Acid Sequence; D019390:Arrestins / Q000235:genetics / Q000378:metabolism*; D018106:CD28 Antigens / Q000378:metabolism; D017252:CD3 Complex / Q000378:metabolism; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism*; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4 / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D008213:Lymphocyte Activation; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000378:metabolism; D021962:Membrane Microdomains / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction / Q000502:physiology*; D013601:T-Lymphocytes / Q000378:metabolism; D000071557:beta-Arrestins
chemical_list: D019390:Arrestins; D018106:CD28 Antigens; D017252:CD3 Complex; D046912:Multiprotein Complexes; D034741:RNA, Small Interfering; D011948:Receptors, Antigen, T-Cell; D000071557:beta-Arrestins; D019869:Phosphatidylinositol 3-Kinases; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D051057:Proto-Oncogene Proteins c-akt; D017868:Cyclic AMP-Dependent Protein Kinases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4