title: FGF-2 induces neuronal death through upregulation of system xc-.
abstract: The cystine/glutamate antiporter (system xc-) transports cystine into cell in exchange for glutamate. Fibroblast growth factor-2 (FGF-2) upregulates system xc- selectively on astrocytes, which leads to increased cystine uptake, the substrate for glutathione production, and increased glutamate release. While increased intracellular glutathione can limit oxidative stress, the increased glutamate release can potentially lead to excitotoxicity to neurons. To test this hypothesis, mixed neuronal and glial cortical cultures were treated with FGF-2. Treatment with FGF-2 for 48 h caused a significant neuronal death in these cultures. Cell death was not observed in neuronal-enriched cultures, or astrocyte-enriched cultures, suggesting the toxicity was the result of neuron-glia interaction. Blocking system xc- eliminated the neuronal death as did the AMPA/kainate receptor antagonist 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione (NBQX), but not the NMDA receptor antagonist memantine. When cultures were exposed directly to glutamate, both NBQX and memantine blocked the neuronal toxicity. The mechanism of this altered profile of glutamate receptor mediated toxicity by FGF-2 is unclear. The selective calcium permeable AMPA receptor antagonist 1-naphthyl acetyl spermine (NASPM) failed to offer protection. The most likely explanation for the results is that 48 h FGF-2 treatment induces AMPA/kainate receptor toxicity through increased system xc- function resulting in increased release of glutamate. At the same time, FGF-2 alters the sensitivity of the neurons to glutamate toxicity in a manner that promotes selective AMPA/kainate receptor mediated toxicity.
authors.affiliation: Department of Biomedical Sciences, Marquette University, 561 N. 15th Street, Room 426, Milwaukee, WI 53233, United States.
authors.forename: Xiaoqian
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Biomedical Sciences, Marquette University, 561 N. 15th Street, Room 426, Milwaukee, WI 53233, United States.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Albano
authors.affiliation: Department of Biomedical Sciences, Marquette University, 561 N. 15th Street, Room 426, Milwaukee, WI 53233, United States. Electronic address: doug.lobner@marquette.edu.
authors.forename: Doug
authors.initials: D
authors.lastname: Lobner
mesh_terms: D026905:Amino Acid Transport Systems / Q000378:metabolism*; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D003553:Cystine / Q000378:metabolism*; D016222:Fibroblast Growth Factor 2 / Q000633:toxicity*; D018698:Glutamic Acid / Q000633:toxicity; D051379:Mice; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism*; D018091:Receptors, AMPA / Q000378:metabolism; D018092:Kainic Acid Receptors / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D026905:Amino Acid Transport Systems; D003553:Cystine; D016222:Fibroblast Growth Factor 2; D018698:Glutamic Acid; D018091:Receptors, AMPA; D018092:Kainic Acid Receptors
keywords: (s)-4-carboxyphenylglycine; 1-naphthyl acetyl spermine; 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo[f]quinoxaline-2,3-dione; 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide; AMPA; CPG; Cystine; DL-threo-β-Benzyloxyaspartic acid; EAAT; Excitotoxicity; FGF-2; GSH; Glutamate; LDH; MTT; NASPM; NBQX; SSZ; System xc-; TBOA; excitatory amino acid transporter; glutathione; lactate dehydrogenase; sulfasalazine