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The selective elimination of messenger RNA underlies the mitosis-meiosis switch in fission yeast.

Yamamoto M - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2010)

Bottom Line: Meiosis-inducing signals in this microbe emanating from environmental conditions including the nutrient status converge on the activity of an RRM-type RNA-binding protein, Mei2.Fission yeast contains an RNA degradation system that selectively eliminates meiosis-specific mRNAs during the mitotic cell cycle.Mmi1, a novel RNA-binding protein of the YTH-family, is essential for this process.

View Article: PubMed Central - PubMed

Affiliation: Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Tokyo, Japan. yamamoto@biochem.s.u-tokyo.ac.jp

ABSTRACT
The cellular programs for meiosis and mitosis must be strictly distinguished but the mechanisms controlling the entry to meiosis remain largely elusive in higher organisms. In contrast, recent analyses in yeast have shed new light on the mechanisms underlying the mitosis-meiosis switch. In this review, the current understanding of these mechanisms in the fission yeast Schizosaccharomyces pombe is discussed. Meiosis-inducing signals in this microbe emanating from environmental conditions including the nutrient status converge on the activity of an RRM-type RNA-binding protein, Mei2. This protein plays pivotal roles in both the induction and progression of meiosis and has now been found to govern the meiotic program in a quite unexpected manner. Fission yeast contains an RNA degradation system that selectively eliminates meiosis-specific mRNAs during the mitotic cell cycle. Mmi1, a novel RNA-binding protein of the YTH-family, is essential for this process. Mei2 tethers Mmi1 and thereby stabilizes the transcripts necessary for the progression of meiosis.

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Ectopic meiosis induced artificially by either inactivation of Pat1 kinase or dephosphorylation of Mei2. Even haploid cells execute meiotic divisions and produce spores, in which chromosomes are distributed unevenly, under these conditions. Left panel: haploid cells in the mitotic cell cycle, shown as a control. Middle panel: pat1-114 cells incubated at the restrictive temperature. Right panel: cells expressing an unphosphorylatable form of Mei2 (Mei2-SATA). Bright regions represent DNA stained with a fluorescent dye. Phase-contrast images are overlaid in the left and middle panels.
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fig03: Ectopic meiosis induced artificially by either inactivation of Pat1 kinase or dephosphorylation of Mei2. Even haploid cells execute meiotic divisions and produce spores, in which chromosomes are distributed unevenly, under these conditions. Left panel: haploid cells in the mitotic cell cycle, shown as a control. Middle panel: pat1-114 cells incubated at the restrictive temperature. Right panel: cells expressing an unphosphorylatable form of Mei2 (Mei2-SATA). Bright regions represent DNA stained with a fluorescent dye. Phase-contrast images are overlaid in the left and middle panels.

Mentions: The independent identification of the pat1 mutation (also known as ran1) by Nurse and by our own laboratory provided a new avenue to analyze the molecular mechanisms underlying the regulation of meiosis in fission yeast.50,51) Yeast cells carrying the pat1-114 mutation isolated in our laboratory, showed temperature-sensitive growth and performed ectopic meiosis and sporulation at high temperature regardless of the nutritional conditions or ploidy state (Fig. 3). Hence, Pat1 was considered to be a factor that normally prevents fission yeast cells from entering meiosis under conditions suitable for vegetative growth.52,53)


The selective elimination of messenger RNA underlies the mitosis-meiosis switch in fission yeast.

Yamamoto M - Proc. Jpn. Acad., Ser. B, Phys. Biol. Sci. (2010)

Ectopic meiosis induced artificially by either inactivation of Pat1 kinase or dephosphorylation of Mei2. Even haploid cells execute meiotic divisions and produce spores, in which chromosomes are distributed unevenly, under these conditions. Left panel: haploid cells in the mitotic cell cycle, shown as a control. Middle panel: pat1-114 cells incubated at the restrictive temperature. Right panel: cells expressing an unphosphorylatable form of Mei2 (Mei2-SATA). Bright regions represent DNA stained with a fluorescent dye. Phase-contrast images are overlaid in the left and middle panels.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3037521&req=5

fig03: Ectopic meiosis induced artificially by either inactivation of Pat1 kinase or dephosphorylation of Mei2. Even haploid cells execute meiotic divisions and produce spores, in which chromosomes are distributed unevenly, under these conditions. Left panel: haploid cells in the mitotic cell cycle, shown as a control. Middle panel: pat1-114 cells incubated at the restrictive temperature. Right panel: cells expressing an unphosphorylatable form of Mei2 (Mei2-SATA). Bright regions represent DNA stained with a fluorescent dye. Phase-contrast images are overlaid in the left and middle panels.
Mentions: The independent identification of the pat1 mutation (also known as ran1) by Nurse and by our own laboratory provided a new avenue to analyze the molecular mechanisms underlying the regulation of meiosis in fission yeast.50,51) Yeast cells carrying the pat1-114 mutation isolated in our laboratory, showed temperature-sensitive growth and performed ectopic meiosis and sporulation at high temperature regardless of the nutritional conditions or ploidy state (Fig. 3). Hence, Pat1 was considered to be a factor that normally prevents fission yeast cells from entering meiosis under conditions suitable for vegetative growth.52,53)

Bottom Line: Meiosis-inducing signals in this microbe emanating from environmental conditions including the nutrient status converge on the activity of an RRM-type RNA-binding protein, Mei2.Fission yeast contains an RNA degradation system that selectively eliminates meiosis-specific mRNAs during the mitotic cell cycle.Mmi1, a novel RNA-binding protein of the YTH-family, is essential for this process.

View Article: PubMed Central - PubMed

Affiliation: Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Tokyo, Japan. yamamoto@biochem.s.u-tokyo.ac.jp

ABSTRACT
The cellular programs for meiosis and mitosis must be strictly distinguished but the mechanisms controlling the entry to meiosis remain largely elusive in higher organisms. In contrast, recent analyses in yeast have shed new light on the mechanisms underlying the mitosis-meiosis switch. In this review, the current understanding of these mechanisms in the fission yeast Schizosaccharomyces pombe is discussed. Meiosis-inducing signals in this microbe emanating from environmental conditions including the nutrient status converge on the activity of an RRM-type RNA-binding protein, Mei2. This protein plays pivotal roles in both the induction and progression of meiosis and has now been found to govern the meiotic program in a quite unexpected manner. Fission yeast contains an RNA degradation system that selectively eliminates meiosis-specific mRNAs during the mitotic cell cycle. Mmi1, a novel RNA-binding protein of the YTH-family, is essential for this process. Mei2 tethers Mmi1 and thereby stabilizes the transcripts necessary for the progression of meiosis.

Show MeSH
Related in: MedlinePlus