3 NF-KAPPA-B SITES IN THE I-KAPPA-B-ALPHA PROMOTER ARE REQUIRED FOR INDUCTION OF GENE-EXPRESSION BY TNF-ALPHA
3 NF-KAPPA-B SITES IN THE I-KAPPA-B-ALPHA PROMOTER ARE REQUIRED FOR INDUCTION OF GENE-EXPRESSION BY TNF-ALPHA
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DOI：
10.1093/nar/22.18.3787
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发表时间：
1994-09-11
影响因子：
14.9
通讯作者：
BALDWIN, AS
中科院分区：
文献类型：
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作者：
ITO, CY;KAZANTSEV, AG;BALDWIN, AS
核因子-kappaB首先被鉴定为正调控因子，结合在lgk轻链基因第一内含子的10个碱基序列上。对该转录因子的进一步鉴定表明，核因子-kappa B被其抑制剂IKB-α阻止与其共同序列结合，后者将核因子-kappaB保留在细胞质中。在接收到各种细胞外和细胞内信号后，I-kappa B-α被迅速降解，并被诱导核转录因子-kappaB移位到细胞核内。这一过程先于I kappa B-αmRNA和蛋白的快速诱导。为了了解I-kappa B-α是如何被补充的，我们克隆并测定了I-kappa B-α基因5‘侧翼区的序列，并确定了该区域的转录起始点和3个核因子-kappa B位点。对这些核因子-KB位点的进一步表征表明，它们对三种特定的蛋白质复合体具有不同的亲和力，我们在这里确定这些复合体由REL家族的不同成员组成。在瞬时检测中，与p65表达载体共转染能够激活I kappa B-α启动子-CAT报告基因构建体，并且在肿瘤坏死因子-α刺激下，所有三个核因子-kappa B位点都是完全激活I kappa B-α基因所必需的。我们的数据证实了参与维持细胞中适当的核因子-kappa B和I-kappa B-α水平的转录自动调节环路。
NF-kappa B was first identified as a postive regulator which bound to a 10 bp sequence in the first intron of the lgk light chain gene. Further characterization of this transcription factor has revealed that NF-kappa B is kept from binding to its consensus sequence by its inhibitor, IkB-alpha, which retains NF-kappa B in the cytoplasm. Upon receiving various extra- and intracellular signals, I kappa B-alpha is rapidly degraded and NF-kappa B is induced to translocate into the nucleus. This process precedes the rapid induction of I kappa B-alpha mRNA and protein. To understand how I kappa B-alpha is replenished, we have cloned and sequenced the 5' flanking region of the I kappa B-alpha gene and have identified the transcription start site and three NF-kappa B sites in this region. Further characterization of these NF-KB sites show that they have different affinities for three specific protein complexes which we identify here to consist of various members of the Rel family. In transient assays, cotransfection with a p65 expression vector is able to activate an I kappa B-alpha promoter-CAT reporter construct and all three NF-kappa B sites are required for full activation of the I kappa B-alpha gene following stimulation with TNF-alpha. Our data confirm a transcriptional autoregulatory loop involved in maintaining appropriate NF-kappa B and I kappa B-alpha levels in the cell.