Yeast heat shock mRNAs are exported through a distinct pathway defined by Rip1p.
Yeast heat shock mRNAs are exported through a distinct pathway defined by Rip1p.
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DOI：
10.1101/gad.11.21.2845
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发表时间：
1997-11
影响因子：
10.5
通讯作者：
C. Saavedra;C. Hammell;C. Heath;Charles N. Cole
中科院分区：
文献类型：
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作者：
C. Saavedra;C. Hammell;C. Heath;Charles N. Cole
我们以前报道过，在酿酒酵母中，热或乙醇休克导致大多数poly（A）+ RNA的核滞留，但热休克mRNA（编码Hsp 70蛋白Ssa 1 p和Ssa 4p）在一个过程中有效地输出，这是独立于小的GTd-Ran/Gsp 1 p，这是最重要的核质运输。为了进一步了解蛋白质的出口的热休克mRNA的必要或非必要的，原位杂交分析，以检测mRNA和脉冲标记的蛋白质被用来检查几个酵母突变株的能力，出口热休克mRNA后的压力。Rip 1 p是一种42 kD的蛋白质，与核孔复合物相关，含有核孔蛋白样重复序列。在正常条件下，它对酵母细胞的生长是有害的，但我们报告说，它对应激后热休克mRNA的输出是必不可少的。当SSA 4 mRNA在不存在应激的情况下从GAL启动子诱导时，它在缺乏RIP 1的菌株中有效地输出，这表明RIP 1 p仅在应激后才需要输出热休克mRNA。Np 13 p是poly（A）+ RNA输出的关键介质，但不参与热休克mRNA的输出，而Rss 1 p/Gle 1 p是poly（A）+ RNA输出所必需的NES因子，也参与热休克mRNA的输出。高水平表达的HIV-1 Rev蛋白，但不是Rev突变体，导致在出口的热休克mRNA应激后的部分封锁。数据提出了一个模型，其中对Npl 3 p的需求定义了mRNA输出途径，对Rip 1 p的需求定义了用于应激后热休克mRNA输出的途径，并且这两种途径都需要其他因素，包括Rss 1 p/Gle 1 p和几种核孔蛋白（Rat 7 p/Nup 159 p、Rat 2 p/Nup 120 p和Nup 145 p/Rat 10 p）。
We reported previously that heat or ethanol shock in Saccharomyces cerevisiae leads to nuclear retention of most poly(A)+ RNA but heat shock mRNAs (encoding Hsp70 proteins Ssa1p and Ssa4p) are efficiently exported in a process that is independent of the small GTPase Ran/Gsp1p, which is essential for most nucleocytoplasmic transport. To gain further insights into proteins essential or nonessential for export of heat shock mRNAs, in situ hybridization analyses to detect mRNA and pulse-labeling of proteins were used to examine several yeast mutant strains for their ability to export heat shock mRNAs following stress. Rip1p is a 42-kD protein associated with nuclear pore complexes and contains nucleoporin-like repeat sequences. It is dispensable for growth of yeast cells under normal conditions, but we report that it is essential for the export of heat shock mRNAs following stress. When SSA4 mRNA was induced from a GAL promoter in the absence of stress, it was efficiently exported in a strain lacking RIP1, indicating that Rip1p is required for export of heat shock mRNAs only following stress. Npl3p, a key mediator of export of poly(A)+ RNA, was not required for heat shock mRNA export, whereas Rss1p/Gle1p, a NES-containing factor essential for poly(A)+ RNA export, was also required for export of heat shock mRNAs after stress. High-level expression of the HIV-1 Rev protein, but not of Rev mutants, led to a partial block in export of heat shock mRNAs following stress. The data suggest a model wherein the requirement for Npl3p defines the mRNA export pathway, the requirement for Rip1p defines a pathway used for export of heat shock mRNAs after stress, and additional factors, including Rss1p/Gle1p and several nucleoporins (Rat7p/Nup159p, Rat2p/Nup120p, and Nup145p/Rat10p), are required in both pathways.