Laboratory of Cell Responses, National Institute for Basic Biology, Okazaki, Japan.
Department of Imaging Science, Center for Novel Science Initiatives, National Institutes of Natural Sciences, Okazaki, Japan.
Elife. 2018 Feb 9;7:e32155. doi: 10.7554/eLife.32155.
Accurate and extensive regulation of meiotic gene expression is crucial to distinguish germ cells from somatic cells. In the fission yeast a YTH family RNA-binding protein, Mmi1, directs the nuclear exosome-mediated elimination of meiotic transcripts during vegetative proliferation. Mmi1 also induces the formation of facultative heterochromatin at a subset of its target genes. Here, we show that Mmi1 prevents the mistimed expression of meiotic proteins by tethering their mRNAs to the nuclear foci. Mmi1 interacts with itself with the assistance of a homolog of Enhancer of Rudimentary, Erh1. Mmi1 self-interaction is required for foci formation, target transcript elimination, their nuclear retention, and protein expression inhibition. We propose that nuclear foci formed by Mmi1 are not only the site of RNA degradation, but also of sequestration of meiotic transcripts from the translation machinery.
准确而广泛地调控减数分裂基因表达对于区分生殖细胞和体细胞至关重要。在裂殖酵母中，一种 YTH 家族 RNA 结合蛋白 Mmi1 在营养生长过程中指导核小体酶复合物介导的减数分裂转录本的消除。Mmi1 还诱导其部分靶基因形成兼性异染色质。在这里，我们发现 Mmi1 通过将其 mRNA 锚定在核斑点上来防止减数分裂蛋白的时机错误表达。Mmi1 在 Enhancer of Rudimentary 同源物 Erh1 的协助下与自身相互作用。Mmi1 自我相互作用对于焦点形成、靶转录本消除、它们的核保留和蛋白质表达抑制是必需的。我们提出，Mmi1 形成的核斑点不仅是 RNA 降解的部位，也是将减数分裂转录本从翻译机制中隔离出来的部位。
