Tani T, Derby R J, Hiraoka Y, Spector D L
Cold Spring Harbor Laboratory, New York 11724, USA.
Mol Biol Cell. 1996 Jan;7(1):173-92. doi: 10.1091/mbc.7.1.173.
Transport of mRNA from the nucleus to the cytoplasm plays an important role in gene expression in eukaryotic cells. In wild-type Schizosaccharomyces pombe cells poly(A)+ RNA is uniformly distributed throughout the nucleoplasm and cytoplasm. However, we found that a severe heat shock blocks mRNA transport in S. pombe, resulting in the accumulation of bulk poly(A)+ RNA, as well as a specific intron-less transcript, in the nucleoli. Pretreatment of cells with a mild heat shock, which induces heat shock proteins, before a severe heat shock protects the mRNA transport machinery and allows mRNA transport to proceed unimpeded. In heat-shocked S. pombe cells, the nucleolar region condensed into a few compact structures. Interestingly, poly(A)+ RNA accumulated predominantly in the condensed nucleolar regions of the heat-shocked cells. These data suggest that the yeast nucleolus may play a role in mRNA transport in addition to its roles in rRNA synthesis and preribosome assembly.
信使核糖核酸（mRNA）从细胞核向细胞质的转运在真核细胞的基因表达中起着重要作用。在野生型粟酒裂殖酵母细胞中，多聚腺苷酸（poly(A)）+RNA均匀分布于整个核质和细胞质中。然而，我们发现严重热休克会阻断粟酒裂殖酵母中的mRNA转运，导致大量poly(A)+RNA以及一种特定的无内含子转录本在核仁中积累。在严重热休克之前，用轻度热休克预处理细胞（轻度热休克可诱导热休克蛋白），可保护mRNA转运机制，并使mRNA转运不受阻碍地进行。在热休克的粟酒裂殖酵母细胞中，核仁区域凝聚成一些紧密结构。有趣的是，poly(A)+RNA主要积累在热休克细胞的凝聚核仁区域。这些数据表明，酵母核仁除了在核糖体RNA（rRNA）合成和前核糖体组装中发挥作用外，可能还在mRNA转运中发挥作用。
