Transcription factor nuclear factor-kappa B is activated in neurons after focal cerebral ischemia
Transcription factor nuclear factor-kappa B is activated in neurons after focal cerebral ischemia
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DOI：
10.1097/00004647-200003000-00017
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发表时间：
2000-03-01
影响因子：
6.3
通讯作者：
Clemens, J
中科院分区：
文献类型：
--
作者：
Stephenson, D;Yin, T;Clemens, J
核因子-kB是一种多亚基转录因子，激活后可诱导编码急性期蛋白、细胞黏附分子、细胞表面受体和细胞因子的基因表达。核因子-kB由多种蛋白质亚基组成，其中p50-kDa和p65-kDa(RelA)是研究最广泛的两个亚基。在静息条件下，这些亚基以抑制蛋白IKBα和IKBβ结合的非活性复合体的形式存在于细胞质中。在激活时，IKB被IKB激酶磷酸化，并被蛋白酶体泛素化和降解；同时，活跃的异源二聚体转移到细胞核，在那里它可以启动基因转录。在外周，核因子-kB通过刺激炎症介质的产生而参与炎症。核因子-kB在大脑中的作用尚不清楚。在试管中。核因子-kB的激活可以是保护性的，也可以是有害的。研究核因子-kB在缺血神经细胞死亡中的作用。成年雄性大鼠采用大脑中动脉闭塞(MCAO)方法复制2小时局灶性脑缺血模型。再灌流后2、6、12小时，用免疫细胞化学和凝胶迁移率分析法检测缺血区和非缺血区皮质和纹状体中核因子-kB的表达和反式激活。在研究的所有时间点。P50和P65免疫反应仅见于缺血侧皮质和纹状体神经元的胞核。对侧非缺血侧大脑半球未见核因子-kB免疫反应。双重免疫荧光证实p50在神经元胞核中有表达。从缺血半球制备的核提取液中核因子-kB DNA结合活性的增加通过凝胶迁移分析进一步得到证实。由于在体外许多刺激对核因子-kB的激活均可被抗氧化剂b1阻断，因此研究了抗氧化剂LY341122对大脑中动脉阻塞模型中核因子-B的激活的影响。经LY341122处理的动物经凝胶迁移率分析未发现明显的核因子-kB活化。这些结果表明，短暂性局灶性脑缺血可导致神经元中核因子-kB的激活，并支持神经保护性抗氧化剂可能通过阻止核因子-kB的激活来抑制神经元死亡的观察。
Nuclear factor-kappa B (NF-kB) is a multisubunit transcription factor that when activated induces the expression of genes encoding acute-phase proteins, cell adhesion molecules, cell surface receptors, and cytokines. NF-kB is composed of a variety of protein subunits of which p50-and p65-kDa (RelA) are the most widely studied. Under resting conditions, these subunits reside in the cytoplasm as an inactive complex bound by inhibitor proteins, IkB alpha and IkB beta. On activation, IkB is phosphorylated by IkB kinase and ubiquitinated and degraded by the proteasome; simultaneously, the active heterodimer translocates to the nucleus where it can initiate gene transcription. In the periphery, NF-kB is involved in inflammation through stimulation of the production of inflammatory mediators. The role of NF-kB in the brain is unclear. In vitro. NF-kB activation can be either protective or deleterious. The role of NF-kB in ischemic neuronal cell death in vivo was investigated. Adult male rats were subjected to 2 hours of focal ischemia induced by middle cerebral artery occlusion (MCAO). At 2. 6, and 12 hours after reperfusion, the expression and transactivation of NF-kB in ischemic versus nonischemic cortex and striatum were determined by immunocytochemistry and by electrophoretic mobility gel-shift analysis. At all time points studied. p50 and p65 immunoreactivity was found exclusively in the nuclei of cortical and striatal neurons in the ischemic hemisphere. The contralateral nonischemic hemisphere showed no evidence of nuclear NF-kB immunoreactivity. Double immunofluorescence confirmed expression of p50 in nuclei of neurons. Increased NF-kB DNA-binding activity in nuclear extracts prepared from the ischemic hemisphere was further substantiated by electrophoretic mobility gel-shift analysis. Because the activation of NF-kB by many stimuli can be blocked by antioxidants bl vitro, the effect of the antioxidant, LY341122, previously shown to be neuroprotective, on NF-LB activation in the MCAO model was evaluated. No significant activation of NF-kB was found by electrophoretic mobility gel-shift analysis in animals treated with LY341122. These results demonstrate that transient focal cerebral ischemia results in activation of NF-kB in neurons and supports previous observations that neuroprotective antioxidants may inhibit neuronal death by preventing the activation of NF-kB.