Identification of a regulated pathway for nuclear pre-mRNA turnover.

We have identified a nuclear pathway that rapidly degrades unspliced pre-mRNAs in yeast. This involves 3'-->5' degradation by the exosome complex and 5'-->3' degradation by the exonuclease Rat1p. 3'-->5' degradation is normally the major pathway and is regulated in response to carbon source. Inhibition of pre-mRNA degradation resulted in increased ...
levels of pre-mRNAs and spliced mRNAs. When splicing was inhibited by mutation of a splicing factor, inhibition of turnover resulted in 20- to 50-fold accumulation of pre-mRNAs, accompanied by increased mRNA production. Splicing of a reporter construct with a 3' splice site mutation was also increased on inhibition of turnover, showing competition between degradation and splicing. We propose that nuclear pre-mRNA turnover represents a novel step in the regulation of gene expression.
Mesh Terms:
Animals, Cell Nucleus, Exoribonucleases, Fungal Proteins, Genotype, Mammals, Mutation, RNA Precursors, RNA Splicing, Saccharomyces cerevisiae Proteins, Yeasts
Cell
Date: Sep. 15, 2000
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