title: Requirement for nitric oxide activation of p21(ras)/extracellular regulated kinase in neuronal ischemic preconditioning.
abstract: The mechanisms underlying neuronal ischemic preconditioning, a phenomenon in which brief episodes of ischemia protect against the lethal effects of subsequent periods of prolonged ischemia, are poorly understood. Ischemia can be modeled in vitro by oxygen-glucose deprivation (OGD). We report here that OGD preconditioning induces p21(ras) (Ras) activation in an N-methyl-D-aspartate receptor- and NO-dependent, but cGMP-independent, manner. We demonstrate that Ras activity is necessary and sufficient for OGD tolerance in neurons. Pharmacological inhibition of Ras, as well as a dominant negative mutant Ras, block OGD preconditioning whereas a constitutively active form of Ras promotes neuroprotection against lethal OGD insults. In contrast, the activity of phosphatidyl inositol 3-kinase is not required for OGD preconditioning because inhibition of phosphatidyl inositol 3-kinase with a chemical inhibitor or with a dominant negative mutant does not have any effect on the development of OGD tolerance. Furthermore, using recombinant adenoviruses and pharmacological inhibitors, we show that downstream of Ras the extracellular regulated kinase cascade is required for OGD preconditioning. Our observations indicate that activation of the Ras/extracellular regulated kinase cascade by NO is a critical mechanism for the development of OGD tolerance in cortical neurons, which may also play an important role in ischemic preconditioning in vivo.
authors.affiliation: Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
authors.forename: M
authors.initials: M
authors.lastname: Gonzalez-Zulueta
authors.forename: A B
authors.initials: AB
authors.lastname: Feldman
authors.forename: L J
authors.initials: LJ
authors.lastname: Klesse
authors.forename: R G
authors.initials: RG
authors.lastname: Kalb
authors.forename: J F
authors.initials: JF
authors.lastname: Dillman
authors.forename: L F
authors.initials: LF
authors.lastname: Parada
authors.forename: T M
authors.initials: TM
authors.lastname: Dawson
authors.forename: V L
authors.initials: VL
authors.lastname: Dawson
mesh_terms: D000256:Adenoviridae / Q000378:metabolism; D000693:Anaerobiosis; D000818:Animals; D001921:Brain / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D005947:Glucose / Q000172:deficiency; D019194:Ischemic Preconditioning; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009025:Morpholines / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology*; D010100:Oxygen / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D016283:Proto-Oncogene Proteins p21(ras) / Q000378:metabolism*; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism; D015398:Signal Transduction; D018139:Simplexvirus / Q000235:genetics; D014162:Transfection
chemical_list: D002867:Chromones; D009025:Morpholines; D016194:Receptors, N-Methyl-D-Aspartate; D009569:Nitric Oxide; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D019869:Phosphatidylinositol 3-Kinases; D020928:Mitogen-Activated Protein Kinases; D016283:Proto-Oncogene Proteins p21(ras); D005947:Glucose; D010100:Oxygen; D002118:Calcium