title: Guanosine inhibits CD40 receptor expression and function induced by cytokines and beta amyloid in mouse microglia cells.
abstract: Growing evidence implicates CD40, a member of the TNFR superfamily, as contributing to the pathogenesis of many neurodegenerative diseases. Thus, strategies to suppress its expression may be of benefit in those disorders. To this aim, we investigated the effect of guanosine, a purine nucleoside that exerts neurotrophic and neuroprotective effects. CD40 expression and function are increased by exposure of mouse microglia cultures or the N9 microglia cell line to IFN-gamma (10 ng/ml) plus TNF-alpha (50 ng/ml) or beta amyloid (Abeta) peptide (Abeta(1-42); 500 nM). Culture pretreatment with guanosine (10-300 microM), starting 1 h before cytokine or Abeta addition, dose-dependently inhibited the CD40-induced expression as well as functional CD40 signaling by suppressing IL-6 production promoted by IFN-gamma/TNF-alpha challenge in the presence of CD40 cross-linking. Moreover, guanosine abrogated IFN-gamma-induced phosphorylation on Ser(727) and translocation of STAT-1alpha to the nucleus as well as TNF-alpha-/Abeta-induced IkappaBalpha and NF-kappaB p65/RelA subunit phosphorylation, thus inhibiting NF-kappaB-induced nuclear translocation. Guanosine effects were mediated by an increased phosphorylation of Akt, a PI3K downstream effector, as well as of ERK1/2 and p38 in the MAPK system, because culture pretreatment with selective ERK1/2, p38 MAPK, and PI3K antagonists (U0126, SB203580, or LY294002, respectively) counteracted guanosine inhibition on IFN-gamma/TNF-alpha-induced CD40 expression and function as well as on STAT-1alpha or NF-kappaB nuclear translocation. These findings suggest a role for guanosine as a potential drug in the experimental therapy of neuroinflammatory/neurodegenerative diseases, particularly Alzheimer's disease.
authors.affiliation: Department of Biomedical Sciences, Section of Pharmacology, University of Chieti, Via dei Vestini 29, 66013 Chieti, Italy.
authors.forename: Iolanda
authors.initials: I
authors.lastname: D'Alimonte
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Flati
authors.forename: Mariagrazia
authors.initials: M
authors.lastname: D'Auro
authors.forename: Elena
authors.initials: E
authors.lastname: Toniato
authors.forename: Stefano
authors.initials: S
authors.lastname: Martinotti
authors.forename: Michel P
authors.initials: MP
authors.lastname: Rathbone
authors.forename: Shucui
authors.initials: S
authors.lastname: Jiang
authors.forename: Patrizia
authors.initials: P
authors.lastname: Ballerini
authors.forename: Patrizia
authors.initials: P
authors.lastname: Di Iorio
authors.forename: Francesco
authors.initials: F
authors.lastname: Caciagli
authors.forename: Renata
authors.initials: R
authors.lastname: Ciccarelli
mesh_terms: D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D000818:Animals; D019013:CD40 Antigens / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D006151:Guanosine / Q000494:pharmacology*; D051550:I-kappa B Kinase / Q000378:metabolism; D050832:Interferon-Stimulated Gene Factor 3 / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology*; D051379:Mice; D017628:Microglia / Q000187:drug effects* / Q000378:metabolism*; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology*; D037342:Pertussis Toxin / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010768:Phosphoserine / Q000378:metabolism; D021122:Protein Subunits / Q000378:metabolism; D021381:Protein Transport; D058915:Purinergic P1 Receptor Antagonists; D058919:Purinergic P2 Receptor Antagonists; D018047:Receptors, Purinergic P1 / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000378:metabolism; D015398:Signal Transduction; D014158:Transcription, Genetic / Q000235:genetics; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
chemical_list: D016229:Amyloid beta-Peptides; D019013:CD40 Antigens; D050832:Interferon-Stimulated Gene Factor 3; D016328:NF-kappa B; D010446:Peptide Fragments; D021122:Protein Subunits; D058915:Purinergic P1 Receptor Antagonists; D058919:Purinergic P2 Receptor Antagonists; D018047:Receptors, Purinergic P1; D018048:Receptors, Purinergic P2; D014409:Tumor Necrosis Factor-alpha; C075222:amyloid beta-protein (1-42); C079868:gamma interferon activation factor; D006151:Guanosine; D010768:Phosphoserine; D007371:Interferon-gamma; D037342:Pertussis Toxin; D019869:Phosphatidylinositol 3-Kinases; D051550:I-kappa B Kinase; D020928:Mitogen-Activated Protein Kinases