title: Quinolinic acid induces neuritogenesis in SH-SY5Y neuroblastoma cells independently of NMDA receptor activation.
abstract: Glutamate and nicotinamide adenine dinucleotide (NAD+) have been implicated in neuronal development and several types of cancer. The kynurenine pathway of tryptophan metabolism includes quinolinic acid (QA) which is both a selective agonist at N-methyl-D-aspartate (NMDA) receptors and also a precursor for the formation of NAD+. The effect of QA on cell survival and differentiation has therefore been examined on SH-SY5Y human neuroblastoma cells. Retinoic acid (RA, 10 μm) induced differentiation of SH-SY5Y cells into a neuronal phenotype showing neurite growth. QA (50-150 nm) also caused a concentration-dependent increase in the neurite/soma ratio, indicating differentiation. Both RA and QA increased expression of the neuronal marker β3-tubulin in whole-cell homogenates and in the neuritic fraction assessed using a neurite outgrowth assay. Expression of the neuronal proliferation marker doublecortin revealed that, unlike RA, QA did not decrease the number of mitotic cells. QA-induced neuritogenesis coincided with an increase in the generation of reactive oxygen species. Neuritogenesis was prevented by diphenylene-iodonium (an inhibitor of NADPH oxidase) and superoxide dismutase, supporting the involvement of reactive oxygen species. NMDA itself did not promote neuritogenesis and the NMDA antagonist dizocilpine (MK-801) did not prevent quinolinate-induced neuritogenesis, indicating that the effects of QA were independent of NMDA receptors. Nicotinamide caused a significant increase in the neurite/soma ratio and the expression of β3-tubulin in the neuritic fraction. Taken together, these results suggest that QA induces neuritogenesis by promoting oxidizing conditions and affecting the availability of NAD+, independently of NMDA receptors.
authors.affiliation: Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, West Medical Building, Glasgow, G12 8QQ, UK.
authors.forename: Juan-Manuel
authors.initials: JM
authors.lastname: Hernandez-Martinez
authors.affiliation: Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, West Medical Building, Glasgow, G12 8QQ, UK.
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Forrest
authors.affiliation: Internal Medicine, Ashtead Hospital, Ashtead, UK.
authors.forename: L Gail
authors.initials: LG
authors.lastname: Darlington
authors.affiliation: Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, West Medical Building, Glasgow, G12 8QQ, UK.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Smith
authors.affiliation: Institute of Neuroscience and Psychology, College of Medical, Veterinary and Life Sciences, University of Glasgow, West Medical Building, Glasgow, G12 8QQ, UK.
authors.forename: Trevor W
authors.identifier: 0000-0002-5532-0031
authors.initials: TW
authors.lastname: Stone
mesh_terms: D045744:Cell Line, Tumor; D016291:Dizocilpine Maleate / Q000494:pharmacology; D000089622:Doublecortin Domain Proteins; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors; D016501:Neurites / Q000187:drug effects* / Q000378:metabolism; D000071446:Neuronal Outgrowth; D009479:Neuropeptides / Q000378:metabolism; D009861:Onium Compounds / Q000494:pharmacology; D017378:Quinolinic Acid / Q000494:pharmacology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000819:agonists* / Q000037:antagonists & inhibitors; D014212:Tretinoin / Q000494:pharmacology; D014404:Tubulin / Q000378:metabolism
chemical_list: D000089622:Doublecortin Domain Proteins; D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D008869:Microtubule-Associated Proteins; D009479:Neuropeptides; D009861:Onium Compounds; D016194:Receptors, N-Methyl-D-Aspartate; D014404:Tubulin; D014212:Tretinoin; C007517:diphenyleneiodonium; D016291:Dizocilpine Maleate; D019255:NADPH Oxidases; D017378:Quinolinic Acid
keywords: 
  NAD
  +
  ; differentiation; glutamate; kynurenines; nicotinamide