Gene expression of the transcription factor NF-kappa B in hippocampus: Regulation by synaptic activity
Gene expression of the transcription factor NF-kappa B in hippocampus: Regulation by synaptic activity
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DOI：
10.1016/0169-328x(95)00229-l
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发表时间：
1996-06-01
期刊：
影响因子：
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通讯作者：
Routtenberg, A
中科院分区：
文献类型：
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作者：
Meberg, PJ;Kinney, WR;Routtenberg, A
核因子-kappa B是一种有效的转录激活剂，它以潜伏的形式存在于细胞质中，与其抑制剂I-kappa B复合。蛋白激酶C(PKC)将I-kappa B磷酸化，释放出核因子-kappa B，使其能够转位到细胞核。由于PKC可以激活核因子-kappaB，而长时程增强(LTP)激活PKC，我们在体内观察了长时程增强(LTP)诱导的海马区核因子-kappaB的表达。我们首先描述了核因子-kappa B亚单位p50和p65，以及I kappa BαmRNAs在海马区每个细胞场的表达。在其他脑区，I kappa Bα基因的表达比p50和p65更具选择性。然后，我们用凝胶迁移率改变分析在海马区全细胞提取液和突触体中显示了特定的核因子-kappa B样DNA结合活性，标准如下：(1)脱氧胆酸盐处理后显示潜在的结合；(2)结合被未标记的kappa B寡核苷酸竞争；以及(3)p50或p65的抗体阻断结合。由于p50基因的表达受核因子-kappa B的自动调节，因此我们使用定量原位杂交技术将其表达作为核因子-kappaB活性的报告。无论是LTP诱导刺激还是低频控制刺激，p50和p65的表达都增加，尽管LTP刺激后p65基因表达的增加比对照刺激更明显。与p50和p65相比，I kappa Bα杂交水平没有增加，但与LTP的大小呈负相关。由于海马区核因子-kappa B亚单位基因的表达随着突触活性的增强而增加，因此核因子-kappa B的激活可能有助于伴随着活性依赖的突触可塑性的靶基因表达的变化，但仅以与其他转录因子结合的方式。
NF-kappa B is a potent transcriptional activator that resides in latent form in the cytoplasm complexed to its inhibitor I kappa B. Phosphorylation of I kappa B by protein kinase C (PKC) releases NF-kappa B, enabling its translocation to the nucleus. Since PKC can activate NF-kappa B and PKC is activated by long-term potentiation (LTP), we investigated NF-kappa B expression after hippocampal LTP induced in vivo. We first described the expression of the NF-kappa B subunits, p50 and p65, and I kappa B alpha mRNAs, in each cell field of the hippocampus. In other brain locations I kappa B alpha mRNA exhibited a more selective expression than p50 and p65. We then demonstrated specific NF-kappa B-like DNA-binding activity in hippocampal whole-cell extracts and in synaptosomes using electrophoretic mobility shift assays by the following criteria: (1) latent binding was revealed after deoxycholate treatment; (2) binding was competed off by unlabeled kappa B oligonucleotides; and (3) antibodies to either p50 or p65 blocked binding. Since p50 gene expression is auto-regulated by NF-kappa B, we used its expression as a reporter for NF-kappa B activity using quantitative in situ hybridization. Both p50 and p65 increased their expression in response to either LTP-inducing or low-frequency control stimulation, although the increase in p65 mRNA levels was greater after LTP than control stimulation. In contrast to p50 and p65, I kappa B alpha hybridization levels were not increased, but were inversely correlated with the magnitude of LTP. Since NF-kappa B subunit gene expression in the hippocampus is increased by augmented synaptic activity, NF-kappa B activation may contribute to alterations in target gene expression that accompany activity-dependent synaptic plasticity, but only in a combinatorial fashion with other transcription factors.