Liang S, Hitomi M, Tartakoff A M
Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106, USA.
Proc Natl Acad Sci U S A. 1995 Aug 1;92(16):7372-5. doi: 10.1073/pnas.92.16.7372.
The mechanisms of export of RNA from the nucleus are poorly understood; however, several viral proteins modulate nucleocytoplasmic transport of mRNA. Among these are the adenoviral proteins E1B-55kDa and E4-34kDa. Late in infection, these proteins inhibit export of host transcripts and promote export of viral mRNA. To investigate the mechanism by which these proteins act, we have expressed them in Saccharomyces cerevisiae. Overexpression of either or both proteins has no obvious effect on cell growth. By contrast, overexpression of E1B-55kDa bearing a nuclear localization signal (NLS) dramatically inhibits cell growth. In this situation, the NLS-E1B-55kDa protein is localized to the nuclear periphery, fibrous material is seen in the nucleoplasm, and poly(A)+ RNA accumulates in the nucleus. Simultaneous overexpression of E4-34kDa bearing or lacking an NLS does not modify these effects. We discuss the mechanisms of selective mRNA transport.
RNA从细胞核输出的机制目前还知之甚少；然而，几种病毒蛋白可调节mRNA的核质运输。其中包括腺病毒蛋白E1B-55kDa和E4-34kDa。在感染后期，这些蛋白会抑制宿主转录本的输出，并促进病毒mRNA的输出。为了研究这些蛋白的作用机制，我们已在酿酒酵母中表达了它们。单独或同时过表达这两种蛋白对细胞生长均无明显影响。相比之下，带有核定位信号（NLS）的E1B-55kDa过表达会显著抑制细胞生长。在这种情况下，NLS-E1B-55kDa蛋白定位于核周边，核质中可见纤维状物质，并且聚腺苷酸（poly(A)+）RNA在细胞核中积累。带有或缺乏NLS的E4-34kDa同时过表达不会改变这些效应。我们讨论了选择性mRNA运输的机制。
