title: SOD1 down-regulates NF-kappaB and c-Myc expression in mice after transient focal cerebral ischemia.
abstract: Reactive oxygen species (ROS) are implicated in reperfusion injury after focal cerebral ischemia (FCI). Reactive oxygen species regulate activity of transcription factors like NF-kappaB. The authors investigated the role of ROS in NF-kappaB activity after FCI using transgenic mice that overexpressed human copper/zinc-superoxide dismutase (SOD1) and that had reduced infarction volume after FCI. Superoxide dismutase transgenic and wild-type mice were subjected to 1 hour of middle cerebral artery occlusion (MCAO) and subsequent reperfusion. Immunohistochemistry showed SOD1 overexpression attenuated ischemia-induced NF-kappaB p65 immunoreactivity. Colocalization of NF-kappaB and the neuronal marker, microtubule-associated proteins (MAPs), showed that NF-kappaB was up-regulated in neurons after FCI. Electrophoretic mobility shift assays showed that SODI overexpression reduced ischemia-induced NF-kappaB DNA binding activity. Supershift assays showed that DNA-protein complexes contained p65 and p50 subunits. Immunoreactivity of c-myc, an NF-kappaB downstream gene, was increased in the ischemic cortex and colocalized with NF-kappaB. Western blotting showed that SOD1 overexpression reduced NF-kappaB and c-Myc protein levels in the ischemic brain. Colocalization of c-Myc and TUNEL staining was observed 24 hours after FCI. The current findings provide the first evidence that SOD1 overexpression attenuates activation of NF-kappaB after transient FCI in mice and that preventing this early activation may block expression of downstream deleterious genes like c-myc, thereby reducing ischemic damage.
authors.affiliation: Department of Neurosurgery, Stanford University School of Medicine, California, USA.
authors.forename: C Y
authors.initials: CY
authors.lastname: Huang
authors.forename: M
authors.initials: M
authors.lastname: Fujimura
authors.forename: N
authors.initials: N
authors.lastname: Noshita
authors.forename: Y Y
authors.initials: YY
authors.lastname: Chang
authors.forename: P H
authors.initials: PH
authors.lastname: Chan
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D053938:DNA Fragmentation; D019281:Dimerization; D015870:Gene Expression; D005786:Gene Expression Regulation; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D016328:NF-kappa B / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000032:analysis / Q000235:genetics* / Q000378:metabolism; D015427:Reperfusion Injury / Q000517:prevention & control; D013482:Superoxide Dismutase / Q000235:genetics / Q000502:physiology*; D000072105:Superoxide Dismutase-1; D020301:Vasospasm, Intracranial / Q000378:metabolism*
chemical_list: D016328:NF-kappa B; D016271:Proto-Oncogene Proteins c-myc; C000606290:SOD1 protein, human; D004247:DNA; C000606291:Sod1 protein, mouse; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1