title: Novel protein kinase C θ: coronin 1A complex in T lymphocytes.
abstract: BACKGROUND
  Protein kinase C-θ (PKCθ) plays an important role in signal transduction down-stream of the T cell receptor and T cells deficient of PKCθ show impaired NF-κB as well as NFAT/AP-1 activation resulting in strongly decreased IL-2 expression and proliferation. However, it is not yet entirely clear, how the function of PKCθ - upon T cell activation - is regulated on a molecular level.
  
  
  RESULTS
  Employing a yeast two-hybrid screen and co-immunoprecipitation analyses, we here identify coronin 1A (Coro1A) as a novel PKCθ-interacting protein. We show that the NH2-terminal WD40 domains of Coro1A and the C2-like domain of PKCθ are sufficient for the interaction. Furthermore, we confirm a physical interaction by GST-Coro1A mediated pull-down of endogenous PKCθ protein. Functionally, wild-type but not Coro1A lacking its actin-binding domain negatively interferes with PKCθ-dependent NF-κB, Cyclin D1 and IL-2 transactivation when analysed with luciferase promoter activation assays in Jurkat T cells. This could be phenocopied by pharmacological inhibitors of actin polymerization and PKC, respectively. Mechanistically, Coro1A overexpression attenuates both lipid raft and plasma membrane recruitment of PKCθ in CD3/CD28-activated T cells. Using primary CD3(+) T cells, we observed that (opposite to PKCθ) Coro1A does not localize preferentially to the immunological synapse. In addition, we show that CD3(+) T cells isolated from Coro1A-deficient mice show impaired IKK/NF-κB transactivation.
  
  
  CONCLUSIONS
  Together, these findings both in Jurkat T cells as well as in primary T cells indicate a regulatory role of Coro1A on PKCθ recruitment and function downstream of the TCR leading to NF-κB transactivation.
authors.affiliation: Department for Pharmacology and Genetics, Division of Translational Cell Genetics, Medical University Innsbruck, Peter Mayr Str. 1a, A-6020, Innsbruck, Austria. kerstin.siegmund@i-med.ac.at.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Siegmund
authors.affiliation: Department for Pharmacology and Genetics, Division of Translational Cell Genetics, Medical University Innsbruck, Peter Mayr Str. 1a, A-6020, Innsbruck, Austria. nikolaus.thuille@i-med.ac.at.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Thuille
authors.affiliation: Department for Pharmacology and Genetics, Division of Translational Cell Genetics, Medical University Innsbruck, Peter Mayr Str. 1a, A-6020, Innsbruck, Austria. nina.krumboeck@i-med.ac.at.
authors.forename: Nina
authors.initials: N
authors.lastname: Posch
authors.affiliation: Department for Pharmacology and Genetics, Division of Translational Cell Genetics, Medical University Innsbruck, Peter Mayr Str. 1a, A-6020, Innsbruck, Austria. friedrich.fresser@i-med.ac.at.
authors.forename: Friedrich
authors.initials: F
authors.lastname: Fresser
authors.affiliation: Department for Pharmacology and Genetics, Division of Translational Cell Genetics, Medical University Innsbruck, Peter Mayr Str. 1a, A-6020, Innsbruck, Austria. gottfried.baier@i-med.ac.at.
authors.forename: Gottfried
authors.initials: G
authors.lastname: Baier
mesh_terms: D000818:Animals; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D019169:Jurkat Cells; D051379:Mice; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism*; D000074121:Protein Kinase C-theta; D021381:Protein Transport / Q000502:physiology; D011948:Receptors, Antigen, T-Cell / Q000235:genetics / Q000378:metabolism; D013601:T-Lymphocytes / Q000166:cytology / Q000378:metabolism*; D015533:Transcriptional Activation / Q000502:physiology
chemical_list: D007527:Isoenzymes; D008840:Microfilament Proteins; D046912:Multiprotein Complexes; D016328:NF-kappa B; D011948:Receptors, Antigen, T-Cell; C072061:coronin proteins; C076233:PRKCQ protein, human; C489593:Prkcq protein, mouse; D011493:Protein Kinase C; D000074121:Protein Kinase C-theta