Kumar R, Azam S, Sullivan J M, Owen C, Cavener D R, Zhang P, Ron D, Harding H P, Chen J J, Han A, White B C, Krause G S, DeGracia D J
Department of Emergency Medicine, Wayne State University, Detroit, Michigan 48201, USA.
J Neurochem. 2001 Jun;77(5):1418-21. doi: 10.1046/j.1471-4159.2001.00387.x.
Reperfusion after global brain ischemia results initially in a widespread suppression of protein synthesis in neurons, which persists in vulnerable neurons, that is caused by the inhibition of translation initiation as a result of the phosphorylation of the alpha-subunit of eukaryotic initiation factor 2 (eIF2alpha). To identify kinases responsible for eIF2alpha phosphorylation [eIF2alpha(P)] during brain reperfusion, we induced ischemia by bilateral carotid artery occlusion followed by post-ischemic assessment of brain eIF2alpha(P) in mice with homozygous functional knockouts in the genes encoding the heme-regulated eIF2alpha kinase (HRI), or the amino acid-regulated eIF2alpha kinase (GCN2). A 10-fold increase in eIF2alpha(P) was observed in reperfused wild-type mice and in the HRI-/- or GCN2-/- mice. However, in all reperfused groups, the RNA-dependent protein kinase (PKR)-like endoplasmic reticulum eIF2alpha kinase (PERK) exhibited an isoform mobility shift on SDS-PAGE, consistent with the activation of the kinase. These data indicate that neither HRI nor GCN2 are required for the large increase in post-ischemic brain eIF2alpha(P), and in conjunction with our previous report that eIF2alpha(P) is produced in the brain of reperfused PKR-/- mice, provides evidence that PERK is the kinase responsible for eIF2alpha phosphorylation in the early post-ischemic brain.
全脑缺血后的再灌注最初会导致神经元中蛋白质合成广泛受抑制，这种抑制在易损神经元中持续存在，其原因是真核起始因子2（eIF2α）的α亚基磷酸化导致翻译起始受到抑制。为了确定脑再灌注期间负责eIF2α磷酸化[eIF2α(P)]的激酶，我们通过双侧颈动脉闭塞诱导缺血，然后对编码血红素调节的eIF2α激酶（HRI）或氨基酸调节的eIF2α激酶（GCN2）基因纯合功能敲除的小鼠进行缺血后脑eIF2α(P)评估。在再灌注的野生型小鼠以及HRI-/-或GCN2-/-小鼠中观察到eIF2α(P)增加了10倍。然而，在所有再灌注组中，RNA依赖性蛋白激酶（PKR）样内质网eIF2α激酶（PERK）在SDS-PAGE上表现出同工型迁移率变化，这与该激酶的激活一致。这些数据表明，缺血后脑eIF2α(P)大幅增加既不需要HRI也不需要GCN2，并且结合我们之前的报告，即再灌注的PKR-/-小鼠脑中产生eIF2α(P)，证明PERK是缺血后早期脑中负责eIF2α磷酸化的激酶。
