title: Nitric oxide inhibits chondrocyte response to IGF-I: inhibition of IGF-IRbeta tyrosine phosphorylation.
abstract: Chondrocytes in arthritic cartilage respond poorly to insulin-like growth factor I (IGF-I). Studies with inducible nitric oxide synthase (iNOS) knockout mice suggest that NO is responsible for part of the cartilage insensitivity to IGF-I. These studies characterize the relationship between NO and chondrocyte responses to IGF-I in vitro, and define a mechanism by which NO decreases IGF-I stimulation of chondrocyte proteoglycan synthesis. Lapine cartilage slices, chondrocytes, and cartilage from osteoarthritic (OA) human knees were exposed to NO from the donors S-nitroso-N-acetylpenicillamine (SNAP) or (Z)-1-[2-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1- ium-1, 2-diolate] (DETA NONOate), by transduction with adenoviral transfer of iNOS (Ad-iNOS), or by activation with interleukin-1 (IL-1). NO synthesis was estimated from medium nitrite, and proteoglycan synthesis was measured as incorporation of (35)SO(4). IGF-I receptor phosphorylation was evaluated with Western analysis. SNAP, DETA NONOate, endogenously synthesized NO in Ad-iNOS-transduced cells, or IL-1 activation decreased IGF-I-stimulated proteoglycan synthesis in cartilage and monolayer cultures of chondrocytes. OA cartilage responded poorly to IGF-I; however, the response to IGF-I was restored by culture with N(G)-monomethyl-L-arginine (L-NMA). IGF-I receptor phosphotyrosine was diminished in chondrocytes exposed to NO. These studies show that NO is responsible for part of arthritic cartilage/chondrocyte insensitivity to anabolic actions of IGF-I; inhibition of receptor autophosphorylation is potentially responsible for this effect.
authors.affiliation: Ferguson Laboratory, Musculoskeletal Research Center, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA. rstuder@pitt.edu
authors.forename: R K
authors.initials: RK
authors.lastname: Studer
authors.forename: E
authors.initials: E
authors.lastname: Levicoff
authors.forename: H
authors.initials: H
authors.lastname: Georgescu
authors.forename: L
authors.initials: L
authors.lastname: Miller
authors.forename: D
authors.initials: D
authors.lastname: Jaffurs
authors.forename: C H
authors.initials: CH
authors.lastname: Evans
mesh_terms: D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D006801:Humans; D066298:In Vitro Techniques; D007334:Insulin-Like Growth Factor I / Q000378:metabolism* / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism* / Q000494:pharmacology; D020030:Nitric Oxide Donors / Q000494:pharmacology; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000378:metabolism; D009603:Nitroso Compounds / Q000494:pharmacology; D010003:Osteoarthritis / Q000378:metabolism* / Q000473:pathology; D010396:Penicillamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D011509:Proteoglycans / Q000096:biosynthesis; D011817:Rabbits; D017526:Receptor, IGF Type 1 / Q000378:metabolism*; D026423:S-Nitroso-N-Acetylpenicillamine; D014443:Tyrosine / Q000378:metabolism; D019323:omega-N-Methylarginine / Q000494:pharmacology
chemical_list: D007375:Interleukin-1; D020030:Nitric Oxide Donors; D009573:Nitrites; D009603:Nitroso Compounds; D011509:Proteoglycans; C094210:2,2'-(hydroxynitrosohydrazono)bis-ethanamine; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D014443:Tyrosine; D007334:Insulin-Like Growth Factor I; D026423:S-Nitroso-N-Acetylpenicillamine; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D017526:Receptor, IGF Type 1; D010396:Penicillamine