Independent contributions of polyomavirus middle T and small T to the regulation of early and late gene expression and DNA replication
Independent contributions of polyomavirus middle T and small T to the regulation of early and late gene expression and DNA replication
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DOI：
10.1128/jvi.00679-06
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发表时间：
2006-08-01
影响因子：
5.4
通讯作者：
Fluck, Michele M.
中科院分区：
文献类型：
--
作者：
Chen, Li;Wang, Xiaoyu;Fluck, Michele M.
我们之前表明，缺乏中T（MT）和小T（ST）功能的鼠多瘤病毒突变体在早期和晚期病毒基因表达以及基因组扩增方面具有严重的多效性缺陷。 MT 和 ST 对这种表型的各自贡献尚不清楚。这项工作区分了 MT 和 ST 在允许的小鼠细胞和非允许的大鼠细胞中的作用。它首次证明了这两种蛋白质的作用。为了深入了解可能需要的信号通路，我们重点关注 MT 及其突变体。结果表明，每个主要的 MT 信号连接、Shc、磷脂酰肌醇 3'-激酶和磷脂酶 C γ 1 都可以以累加的方式发挥作用。出乎意料的是，由于三个主要酪氨酸已转化为苯丙氨酸，缺乏所有这些连接的突变体保留了一些活性。所有 6 个 MT C 端酪氨酸都发生突变的突变体是无活性的。这表明 MT 存在一种使用次要酪氨酸的新信号通路。 ST 和各个 MT 信号传导途径的共同点是能够向多瘤病毒增强子，特别是关键的 AP-1 和 PEA3/ets 结合位点发出信号。这种联系解释了 MT 和 ST 对转录和 DNA 复制的多效性影响。
We previously showed that murine polyomavirus mutants that lack both middle T (MT) and small T (ST) functions have a severe pleiotropic defect in early and late viral gene expression as well as genome amplification. The respective contribution of MT and ST to this phenotype was unclear. This work separates the roles of MT and ST in both permissive mouse cells and nonpermissive rat cells. It demonstrates for the first time a role for both proteins. To gain insight into the signaling pathways that might be required, we focused on MT and its mutants. The results show that each of the major MT signaling connections, Shc, phosphatidylinositol 3'-kinase, and phospholipase C gamma 1, could contribute in an additive way. Unexpectedly, a mutant lacking all these connections because the three major tyrosines had been converted to phenylalanine retained some activity. A mutant in which all six MT C-terminal tyrosines had been mutated was inactive. This suggests a novel signaling pathway for MT that uses the minor tyrosines. What is common to ST and the individual MT signaling pathways is the ability to signal to the polyomavirus enhancer, in particular to the crucial AP-1 and PEA3/ets binding sites. This connection explains the pleiotropy of MT and ST effects on transcription and DNA replication.