Truncated c-Myb expression in the human leukemia cell line TK-6
Truncated c-Myb expression in the human leukemia cell line TK-6
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DOI：
10.1038/sj.leu.2401113
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发表时间：
1998-09-01
期刊：
影响因子：
11.4
通讯作者：
Saito, H
中科院分区：
文献类型：
--
作者：
Tomita, A;Watanabe, T;Saito, H
c-MYB原癌基因编码一种在造血过程中起重要作用的转录因子。我们在T细胞危象中的慢性髓性白血病患者TK-6细胞系中检测到截断的c-MYB mRNA （2.0 kb）和c-MYB蛋白（55 kDa）。从TK-6细胞cDNA文库中分离到突变的c-MYB cDNA克隆（WTK-1），并对其进行了完整的测序。与野生型人c-MYB序列相比，WTK-1序列在第9外显子3′端出现分化。终止密码子出现在分化点下游的第二个密码子，之后是一个以前未知的重排序列。由WTK-1编码的概念蛋白（Myb(TK-6)）包含402个氨基酸，缺乏正常c-Myb的负调控结构域，使人联想到Myb蛋白的活化形式。NIH3T3细胞荧光素酶报告基因检测显示，编码Myb（TK-6）的表达载体比编码野生型人c-Myb的表达载体更有效地刺激Myb调控的mim-1启动子，这表明Myb（TK-6）具有转录因子的功能，因此可能是一种潜在的转化蛋白。Southern blot和突变等位基因特异性聚合酶链反应分析显示，TK-6中相同的c-MYB基因重排出现在晚期，而不是早期，从患者身上获得的标本，表明这种突变是在疾病进展期间获得的。
The c-MYB proto-oncogene encodes a transcription factor which plays an important role in hematopoiesis. We detected truncated c-MYB mRNA (2.0 kb) and c-Myb protein (55 kDa) in the TK-6 cell line, which was established from a patient with chronic myelogenous leukemia in T cell blast crisis. Mutated c-MYB cDNA clone (WTK-1) was isolated from a TK-6 cell cDNA library and sequenced in its entirety. Compared with the wildtype human c-MYB sequence, the WTK-1 sequence diverged at the 3' ends of exons 9. A termination codon was present as the second codon downstream from the point of divergence and was followed by a previously unknown rearranged sequence. The conceptual protein encoded by WTK-1 (Myb(TK-6)) comprises 402 amino acids and lacks the negative regulatory domain of the normal c-Myb, reminiscent of the activated form of Myb protein. Luciferase reporter assay in NIH3T3 cells showed that the expression vector encoding Myb(TK-6) stimulated Myb-regulated mim-1 promoter more effectively than that encoding wild-type human c-Myb, suggesting that Myb(TK-6) is functional as a transcription factor, and thus as a potential transforming protein. Southern blot and mutant allele-specific polymerase chain reaction analyses showed that the same rearrangement of the c-MYB gene in TK-6 was present in late, but not in early, specimens obtained from the patient, indicating that this mutation had been acquired during disease progression.