Abstract
A number of meiosis-specific mRNAs are initially weakly transcribed, but then selectively removed during fission yeast mitotic growth. These mRNAs harbour a region termed DSR (determinant of selective removal), which is recognized by the YTH family RNA-binding protein Mmi1p. Mmi1p directs the destruction of these mRNAs in collaboration with nuclear exosomes. However, detailed molecular mechanisms underlying this process of selective mRNA elimination have remained elusive. In this study, we demonstrate the critical role of polyadenylation in this process. Two-hybrid and genetic screens revealed potential interactions between Mmi1p and proteins involved in polyadenylation. Additional investigations showed that destruction of DSR-containing mRNAs by exosomes required polyadenylation by a canonical poly(A) polymerase. The recruitment of Pab2p, a poly(A)-binding protein, to the poly(A) tail was also necessary for mRNA destruction. In cells undergoing vegetative growth, Mmi1p localized with exosomes, Pab2p, and components of the polyadenylation complex in several patchy structures in the nucleoplasm. These patches may represent the sites for degradation of meiosis-specific mRNAs with untimely expression.
Highlights
Most eukaryotic cells have the genetic potential to carry out meiosis, but in reality only a limited population of cells, such as germ cells, performs meiotic division
Identification of factors involved in 30-end processing of mRNA, which participate in selective mRNA elimination To search for factors that might cooperate with Mmi1p in facilitating selective elimination of meiosis-specific mRNAs, we carried out a genome-wide, yeast two-hybrid screen using Mmi1p as bait
Excessive polyadenylation of meiosis-specific mRNAs generated in an exosome mutant We have previously shown that Mmi1p could physically interact with Rrp6p (Harigaya et al, 2006), which is a nucleus-specific subunit of the exosome
Summary
Most eukaryotic cells have the genetic potential to carry out meiosis, but in reality only a limited population of cells, such as germ cells, performs meiotic division. & 2010 European Molecular Biology Organization mitotic and meiotic cell division programmes Consistent with this hypothesis, our previous analyses revealed that the fission yeast, Schizosaccharomyces pombe, possesses a mechanism for the elimination of meiosis-specific mRNAs from vegetatively growing cells (Harigaya et al, 2006). These mRNAs harbour a unique region, termed DSR (determinant for selective removal), which serves as a marker for mRNA degradation. The Mei dot was observed to be composed of Mei2p and meiRNA encoded by the sme gene, and to be attached to the sme locus on chromosome II (Watanabe et al, 1997; Yamashita et al, 1998; Shimada et al, 2003)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
