Department of Biophysics and Biochemistry, Graduate School of Science, University of Tokyo, Tokyo, Japan.
Proc Jpn Acad Ser B Phys Biol Sci. 2010;86(8):788-97. doi: 10.2183/pjab.86.788.
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.
有丝分裂和减数分裂的细胞程序必须严格区分，但在高等生物中，控制进入减数分裂的机制在很大程度上仍难以捉摸。相比之下，酵母的最新分析为有丝分裂-减数分裂转换的机制提供了新的线索。在这篇综述中，讨论了裂殖酵母 Schizosaccharomyces pombe 中这些机制的最新理解。这种微生物中的诱导减数分裂的信号来自环境条件，包括营养状况，集中在 RRM 型 RNA 结合蛋白 Mei2 的活性上。该蛋白在减数分裂的诱导和进展中发挥关键作用，现在已被发现以一种相当出乎意料的方式控制减数分裂程序。裂殖酵母含有一种 RNA 降解系统，该系统在有丝分裂细胞周期中选择性地消除减数分裂特异性 mRNAs。YTH 家族的新型 RNA 结合蛋白 Mmi1 对于这个过程是必不可少的。Mei2 连接 Mmi1 并稳定减数分裂进展所需的转录本。
