title: Effect of brain ischemia and reperfusion on the localization of phosphorylated eukaryotic initiation factor 2 alpha.
abstract: Postischemic brain reperfusion is associated with a substantial and long-lasting reduction of protein synthesis in selectively vulnerable neurons. Because the overall translation initiation rate is typically regulated by altering the phosphorylation of serine 51 on the alpha-subunit of eukaryotic initiation factor 2 (eIF-2 alpha), we used an antibody specific to phosphorylated eIF-2 alpha [eIF-2(alpha P)] to study the regional and cellular distribution of eIF-2(alpha P) in normal, ischemic, and reperfused rat brains. Western blots of brain postmitochondrial supernatants revealed that approximately 1% of all eIF-2 alpha is phosphorylated in controls, eIF-2(alpha P) is not reduced by up to 30 minutes of ischemia, and eIF-2(alpha P) is increased approximately 20-fold after 10 and 90 minutes of reperfusion. Immunohistochemistry shows localization of eIF-2(alpha P) to astrocytes in normal brains, a massive increase in eIF-2(alpha P) in the cytoplasm of neurons within the first 10 minutes of reperfusion, accumulation of eIF-2(alpha P) in the nuclei of selectively vulnerable neurons after 1 hour of reperfusion, and morphology suggesting pyknosis or apoptosis in neuronal nuclei that continue to display eIF-2(alpha P) after 4 hours of reperfusion. These observations, together with the fact that eIF-2(alpha P) inhibits translation initiation, make a compelling case that eIF-2(alpha P) is responsible for reperfusion-induced inhibition of protein synthesis in vulnerable neurons.
authors.affiliation: Department of Emergency Medicine, Wayne State University School of Medicine, Detroit, MI 48201, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: DeGracia
authors.forename: J M
authors.initials: JM
authors.lastname: Sullivan
authors.forename: R W
authors.initials: RW
authors.lastname: Neumar
authors.forename: S S
authors.initials: SS
authors.lastname: Alousi
authors.forename: K R
authors.initials: KR
authors.lastname: Hikade
authors.forename: J E
authors.initials: JE
authors.lastname: Pittman
authors.forename: B C
authors.initials: BC
authors.lastname: White
authors.forename: J A
authors.initials: JA
authors.lastname: Rafols
authors.forename: G S
authors.initials: GS
authors.lastname: Krause
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000378:metabolism*; D007150:Immunohistochemistry; D008297:Male; D010766:Phosphorylation; D051381:Rats; D015427:Reperfusion Injury / Q000378:metabolism*; D019892:eIF-2 Kinase / Q000032:analysis / Q000378:metabolism*
chemical_list: D019892:eIF-2 Kinase