CLONING 2 ISOFORMS OF RAT CYCLOOXYGENASE - DIFFERENTIAL REGULATION OF THEIR EXPRESSION
CLONING 2 ISOFORMS OF RAT CYCLOOXYGENASE - DIFFERENTIAL REGULATION OF THEIR EXPRESSION
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DOI：
10.1006/abbi.1993.1601
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发表时间：
1993-12-01
影响因子：
3.9
通讯作者：
HWANG, D
中科院分区：
文献类型：
--
作者：
FENG, L;SUN, WQ;HWANG, D
已在真核细胞中鉴定出环氧合酶（考克斯）的两种同工型：由2.8 kb mRNA编码的考克斯-1和由4 kb mRNA编码的有丝分裂原诱导型考克斯-2。我们从脂多糖（LPS）刺激的大鼠腹腔巨噬细胞构建的cDNA文库中克隆了考克斯-1和考克斯-2的cDNA。推导的氨基酸序列表明，考克斯- I含有602个氨基酸，而考克斯-2含有604个氨基酸。考克斯-1开放阅读框的核苷酸序列在大鼠和小鼠之间有95%的保守性，而3′端非翻译区的核苷酸序列除了终止密码子附近的一段150 bp的片段与小鼠不同源外，其余的核苷酸序列的同源性为68%。将两种考克斯cDNA转染Cos-7细胞，导致考克斯活性增加。通过酶活性、考克斯蛋白免疫沉淀和mRNA分析评估，在大鼠血管平滑肌细胞中，白细胞介素-1 β选择性增加考克斯-2的表达，但不增加考克斯-1的表达。在所测试的组织中，仅脑表现出作为酶的主要形式的考克斯-2的基础表达。然而，考克斯-2 mRNA在肺和肾脏中表达，但在心脏中没有，表明考克斯-2而不是考克斯-1在内毒素休克期间花生四烯酸的COX衍生产物的产生中起主要作用。因此，这两种考克斯亚型的表达是不同的，并且考克斯-2在大鼠中响应于炎症刺激而被选择性地诱导。
Two isoforms of cyclooxygenase (COX) have been identified in eukaryotic cells: COX-1 encoded by a 2.8-kb mRNA, and a mitogen-inducible COX-2 encoded by a 4-kb mRNA. We have cloned the COX-1 and COX-2 cDNAs from the cDNA library constructed from lipopolysaccharide (LPS)-stimulated rat peritoneal macrophages. The deduced amino acid sequence showed that COX- I contained 602 amino acids, whereas COX-2 contained 604 amino acids. There is 95% conservation of the nucleotide sequence in the open reading frame of COX-1 between the rat and the mouse, while the homology of the 3′ untranslated region is 68% except for a 150 bp segment adjacent to the stop codon which is nonhomologous with the mouse. Transfection of both COX cDNAs into Cos-7 cells resulted in increased COX activity. In rat vascular smooth muscle cells, interleukin-1β selectively increased the expression of COX-2, but not that of COX-1, as assessed by enzyme activity, immunoprecipitation of COX proteins, and mRNA analysis. Only the brain among tissues tested exhibits basal expression of COX-2 as the major form of the enzyme. However, COX-2 mRNA was expressedin vivoin the lung and kidney, but not in the heart, after systemic administration of LPS, suggesting that COX-2 but not COX-1 plays a major role in producing COX-derived products of arachidonic acid during endotoxic shock. Thus, the two COX isoforms were differentially expressed, and COX-2 was selectively induced in response to inflammatory stimuli in rats.