FUNCTIONAL COMPLEMENTATION OF THE ADENOVIRUS E1B 19-KILODALTON PROTEIN WITH IN THE INHIBITION OF APOPTOSIS IN INFECTED-CELLS
FUNCTIONAL COMPLEMENTATION OF THE ADENOVIRUS E1B 19-KILODALTON PROTEIN WITH IN THE INHIBITION OF APOPTOSIS IN INFECTED-CELLS
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DOI：
10.1128/jvi.68.10.6553-6566.1994
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发表时间：
1994-10-01
影响因子：
5.4
通讯作者：
WHITE, E
中科院分区：
文献类型：
--
作者：
CHIOU, SK;TSENG, CC;WHITE, E
腺病毒E1 A癌基因的表达诱导细胞凋亡，这阻碍了原代啮齿动物细胞的转化和人细胞的生产性腺病毒感染。E1 A与E1 B 19，000-分子量蛋白（19 K蛋白）或Bcl-2蛋白的共表达是有效转化所必需的，这两种蛋白都具有抗凋亡活性。E1 A在啮齿动物细胞中诱导凋亡是由p53肿瘤抑制基因介导的，并且E1 B 19 K蛋白和Bcl-2蛋白都可以克服这种p53依赖性凋亡。Bcl-2和E1 B 19 K蛋白之间的功能相似性表明，它们可能通过相似的机制起作用，并且Bcl-2可能补充生产性感染期间对E1 B 19 K表达的需求。用E1 B 19 K功能丧失突变型腺病毒感染人HeLa细胞产生细胞凋亡，其特征在于增强的细胞病变效应（cyt表型）和宿主细胞染色体DNA和病毒DNA的降解（deg表型）。未能抑制细胞凋亡导致宿主细胞过早死亡，这损害了病毒产量。HeLa细胞由于表达人乳头瘤病毒E6蛋白而表达极低水平的p53。在腺病毒感染过程中，E1 A表达显著增加了p53的水平。因此，E1 A可能通过抑制E6诱导的p53降解和促进p53积累而诱导细胞凋亡。在用E1 B 19 K（-）突变腺病毒感染的HeLa细胞中稳定的Bcl-2过表达阻断了cyt和deg表型的诱导。Bcl-2在HeLa细胞中的表达也赋予了对肿瘤坏死因子α和Fas抗原介导的细胞凋亡的抗性，这也是E1 B 19 K蛋白的既定功能。Bcl-2家族成员的氨基酸序列与E1 B 19 K蛋白的氨基酸序列的比较表明，E1 B 19 K和Bcl-2的中心保守结构域之间存在有限的氨基酸序列同源性。E1 B 19 K蛋白的该结构域在细胞凋亡的转化和调节中是重要的，如通过突变分析所确定的。有限的序列同源性和功能等效性提供了进一步的证据，即Bcl-2和E1 B 19 K蛋白可能具有相关的作用机制，并且E1 B 19 K蛋白可能是细胞Bcl-2蛋白的腺病毒等效物。
Expression of the adenovirus E1A oncogene induces apoptosis which impedes both the transformation of primary rodent cells and productive adenovirus infection of human cells. Coexpression of E1A with the E1B 19,000-molecular-weight protein (19K protein) or the Bcl-2 protein, both of which have antiapoptotic activity, is necessary for efficient transformation. Induction of apoptosis by E1A in rodent cells is mediated by the p53 tumor suppressor gene, and both the E1B 19K protein and the Bcl-2 protein can overcome this p53-dependent apoptosis. The functional similarity between Bcl-2 and the E1B 19K protein suggested that they may act by similar mechanisms and that Bcl-2 may complement the requirement for E1B 19K expression during productive infection. Infection of human HeLa cells with E1B 19K loss-of-function mutant adenovirus produces apoptosis characterized by enhanced cytopathic effects (cyt phenotype) and degradation of host cell chromosomal DNA and viral DNA (deg phenotype). Failure to inhibit apoptosis results in premature host cell death, which impairs virus yield. HeLa cells express extremely low levels of p53 because of expression of human papillomavirus E6 protein. Levels of p53 were substantially increased by E1A expression during adenovirus infection. Therefore, E1A may induce apoptosis by overriding the E6-induced degradation of p53 and promoting p53 accumulation. Stable Bcl-2 overexpression in HeLa cells infected with the E1B 19K(-) mutant adenovirus blocked the induction of the cyt and deg phenotypes. Expression of Bcl-2 in HeLa cells also conferred resistance to apoptosis mediated by tumor necrosis factor alpha and Fas antigen, which is also an established function of the E1B 19K protein. A comparison of the amino acid sequences of Bcl-2 family members and that of the E1B 19K protein indicated that there was limited amino acid sequence homology between the central conserved domains of E1B 19K and Bcl-2. This domain of the E1B 19K protein is important in transformation and regulation of apoptosis, as determined by mutational analysis. The limited sequence homology and functional equivalency provided further evidence that the Bcl-2 and E1B 19K proteins may possess related mechanisms of action and that the E1B 19K protein may be the adenovirus equivalent of the cellular Bcl-2 protein.