ALL 3 DOMAINS OF THE EPSTEIN-BARR VIRUS-ENCODED LATENT MEMBRANE-PROTEIN LMP-1 ARE REQUIRED FOR TRANSFORMATION OF RAT-1 FIBROBLASTS
ALL 3 DOMAINS OF THE EPSTEIN-BARR VIRUS-ENCODED LATENT MEMBRANE-PROTEIN LMP-1 ARE REQUIRED FOR TRANSFORMATION OF RAT-1 FIBROBLASTS
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DOI：
10.1128/jvi.67.3.1638-1646.1993
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发表时间：
1993-03-01
影响因子：
5.4
通讯作者：
THORLEYLAWSON, DA
中科院分区：
文献类型：
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作者：
MOORTHY, RK;THORLEYLAWSON, DA
LMP-1（Epstein-Barr 病毒潜伏膜蛋白 1）是该病毒编码的唯一蛋白，已被证明在啮齿动物成纤维细胞（如 Rat-1 细胞）中具有转化癌基因的特性。 LMP-1 在 Rat-1 细胞中以类似于人类淋巴细胞中所见的方式被磷酸化和蛋白水解裂解。在这项研究中，我们证明了 LMP-1 的所有三个主要结构域（N 端、跨膜和 C 端结构域）对于培养中转化 Rat-I 细胞的能力是必需的，通过失去接触抑制进行测定。这项研究首次证明了 LMP-1 C 末端结构域的功能作用。我们的分析表明，C 末端至少有三个不同的区域参与信号传导。氨基酸306至334在缺乏氨基酸334至364的情况下产生毒性信号，而最后23个氨基酸，即364至386，对于转化是必需的。对缺失三个结构域的LMP-1突变体的生化分析表明，缺失结构域的突变体N端磷酸化正常，但与野生型LMP-1相比，裂解效率较低。删除跨膜结构域的突变体也被磷酸化，但没有被切割，表明LMP-1的磷酸化不需要膜缔合。 C 端结构域缺失且缺少最后 23 个氨基酸的非转化突变体被磷酸化并被切割。因此，仅这些处理事件不足以生成转换信号。
LMP-1, the Epstein-Barr virus latent membrane protein 1, is the only protein encoded by the virus that has been shown to have the properties of a transforming oncogene in rodent fibroblasts such as Rat-1 cells. LMP-1 is phosphorylated and proteolytically cleaved in Rat-1 cells in a manner similar to that seen in human lymphocytes. In this study, we demonstrate that all three major domains of LMP-1 (N-terminal, transmembrane, and C-terminal domains) are required for the ability to transform Rat-I cells in culture, as assayed by loss of contact inhibition. This study is the first demonstration of a functional role for the C-terminal domain of LMP-1. Our analysis suggests that there are at least three distinct regions of the C terminus involved in signalling. Amino acids 306 to 334, which generate a toxic signal in the absence of amino acids 334 to 364, and the last 23 amino acids, 364 to 386, are essential for transformation. Biochemical analysis of the LMP-1 mutants with the three domains deleted indicate that the mutant N-terminal with the domain deleted is phosphorylated normally but is inefficiently cleaved compared with the wild-type LMP-1. The mutant with the transmembrane domain deleted is also phosphorylated but is not cleaved, showing that phosphorylation of LMP-1 does not require membrane association. The nontransforming mutant with the C-terminal domain deleted that lacks the last 23 amino acids is phosphorylated and cleaved. Therefore, these processing events alone are insufficient to generate a transforming signal.