A novel lipopolysaccharide-induced transcription factor regulating tumor necrosis factor α gene expression:: Molecular cloning, sequencing, characterization, and chromosomal assignment
A novel lipopolysaccharide-induced transcription factor regulating tumor necrosis factor α gene expression:: Molecular cloning, sequencing, characterization, and chromosomal assignment
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DOI：
10.1073/pnas.96.8.4518
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发表时间：
1999-04-13
影响因子：
11.1
通讯作者：
Amar, S
中科院分区：
文献类型：
--
作者：
Myokai, F;Takashiba, S;Amar, S
脂多糖（LPS）是单核细胞和巨噬细胞的强效刺激物，引起肿瘤坏死因子α (tnf - α)和其他炎症介质的分泌。鉴于tnf - α对宿主的有害影响，人们认为必须严格调节tnf - α基因的表达。控制人类tnf - α基因转录的核因子的性质仍然不清楚，尽管已经提出了nf - κ B。我们之前关于巨噬细胞对LPS反应的研究发现，在人类tnf - α启动子-550至-487处有一个新的dna结合区域，该区域具有转录活性，但缺乏任何已知的nf - κ b结合位点。我们利用该DNA片段分离纯化了与该片段结合的60 kda蛋白，并获得了其氨基末端序列，用于设计退化探针筛选THP-1细胞的cDNA文库。分离得到一个新的cDNA (1.8 kb)，并对其进行了全测序。该cDNA克隆的鉴定表明，其诱导依赖于LPS对THP-1细胞的激活；因此命名为lps诱导的tnf - α因子（LITAF）。抑制THP-1细胞中LITAF mRNA的表达导致tnf - α转录物的减少。此外，LITAF mRNA的高水平表达主要见于胎盘、外周血白细胞、淋巴结和脾脏。最后，利用荧光原位杂交技术进行染色体定位，发现LITAF定位于16p12-16p13.3染色体。综上所述，这些发现提示LITAF在人类tnf - α基因的激活中起重要作用，并提出了一种控制tnf - α基因表达的新机制。
Lipopolysaccharide (LPS) is a potent stimulator of monocytes and macrophages, causing secretion of tumor necrosis factor alpha (TNF-alpha) and other inflammatory mediators. Given the deleterious effects to the host of TNF-alpha, it has been postulated that TNF-alpha gene expression must be tightly regulated. The nature of the nuclear factor(s) that control TNF-alpha gene transcription in humans remains obscure, although NF-kappa B has been suggested. Our previous studies pertaining to macrophage response to LPS identified a novel DNA-binding domain located from -550 to -487 in the human TNF-alpha promoter that contains transcriptional activity, but lacks any known NF-kappa B-binding sites. We have used this DNA fragment to isolate and purify a 60-kDa protein binding to this fragment and obtained its aminoterminal sequence, which was used to design degenerate probes to screen a cDNA library from THP-1 cells. A novel cDNA done (1.8 kb) was isolated and fully sequenced. Characterization of this cDNA clone revealed that its induction was dependent on LPS activation of THP-1 cells; hence, the name LPS-induced TNF-alpha factor (LITAF). Inhibition of LITAF mRNA expression in THP-1 cells resulted in a reduction of TNF-alpha transcripts. In addition, high level of expression of LITAF mRNA was observed predominantly in the placenta, peripheral blood leukocytes, lymph nodes, and the spleen. Finally, chromosomal localization using fluorescence in situ hybridization revealed that LITAF mapped to chromosome 16p12-16p13.3. Together, these findings suggest that LITAF plays an important role in the activation of the human TNF-alpha gene and proposes a new mechanism to control TNF-alpha gene expression.