Nuclear Retention of Unspliced mRNAs in Yeast Is Mediated by Perinuclear Mlp1

Cell, Volume 116, Issue 1, 9 January 2004, Pages 63-73
Vincent Galy, Olivier Gadal, Micheline Fromont-Racine, Alper Romano, Alain Jacquier and Ulf Nehrbass

Summary

The molecular mechanism underlying the retention of intron-containing mRNAs in the nucleus is not understood. Here, we show that retention of intron-containing mRNAs in yeast is mediated by perinuclearly located Mlp1. Deletion of impairs retention while having no effect on mRNA splicing. The Mlp1-dependent leakage of intron-containing RNAs is increased in presence of , a splicing mutant. When overall pre-mRNA levels are increased by deletion of a nuclear exosome component, deletion augments leakage of only the intron-containing portion of mRNAs. Our data suggest, moreover, that Mlp1-dependent retention is mediated via the 5 splice site. Intriguingly, we found Mlp-proteins to be present only on sections of the NE adjacent to chromatin. We propose that at this confined site the perinuclear Mlp1 implements a quality control step prior to export, physically retaining faulty pre-mRNAs.