Nucleolar accumulation of poly (A)+ RNA in heat-shocked yeast cells: implication of nucleolar involvement in mRNA transport.
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.
Tani
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Cold Spring Harbor Laboratory, New York 11724, USA.
Derby
R J
RJ
Hiraoka
Y
Y
Spector
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DL
D001483:Base Sequence; D002466:Cell Nucleolus / Q000378:metabolism* / Q000648:ultrastructure; D003513:Cycloheximide / Q000494:pharmacology; D006358:Hot Temperature; D017403:In Situ Hybridization; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D015345:Oligonucleotide Probes; D012333:RNA, Messenger / Q000378:metabolism*; D012568:Schizosaccharomyces / Q000378:metabolism* / Q000648:ultrastructure
D015345:Oligonucleotide Probes; D012333:RNA, Messenger; D003513:Cycloheximide