Rie1 and Sgn1 form an RNA-binding complex that enforces the meiotic entry cell fate decision.
Rie1 and Sgn1 form an RNA-binding complex that enforces the meiotic entry cell fate decision.
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Rie1 和 Sgn1 形成 RNA 结合复合物，强制决定减数分裂进入细胞的命运。
DOI：
10.1083/jcb.202302074
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Berchowitz,LukeE
中科院分区：
文献类型：
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作者：
Gaspary,Alec;Laureau,Raphaelle;Dyatel,Annie;Dursuk,Gizem;Simon,Yael;Berchowitz,LukeE
出芽酵母细胞有能力根据环境条件采取少数但不同的生理状态。营养细胞通过出芽迅速增殖，而孢子可以在长时间的营养缺乏和/或干燥中存活。酵母细胞是否会进入减数分裂和孢子形成是一个关键的决定，如果做出错误可能会致命。大多数细胞命运决定，包括酵母的细胞命运决定，被认为是由主转录因子的激活触发的。然而，在转录后强制细胞命运的机制更难实现。在这里，我们进行了正向遗传筛选，以确定在转录后水平影响减数分裂进入的 RNA 结合蛋白。我们的筛选发现了几个具有减数分裂进入表型的候选者，其中最重要的是 RIE1，它编码含有 RRM 的蛋白质。我们证明 Rie1 结合 RNA，与翻译机制相关，并在转录后发挥作用，在孢子形成条件下增强主转录因子 Ime1 的蛋白质水平。我们还鉴定了 Rie1 的物理结合伴侣 Sgn1，它是另一种包含 RRM 的蛋白，在 Ime1 的及时表达中发挥作用。我们证明这些蛋白质独立于细胞大小调节途径来促进减数分裂进入。我们提出了一个模型，解释组成型表达的RNA结合蛋白（例如Rie1和Sgn1）如何在细胞命运决定中发挥作用，既作为开关样执行者又作为虚假细胞命运激活的抑制子。
Budding yeast cells have the capacity to adopt few but distinct physiological states depending on environmental conditions. Vegetative cells proliferate rapidly by budding while spores can survive prolonged periods of nutrient deprivation and/or desiccation. Whether or not a yeast cell will enter meiosis and sporulate represents a critical decision that could be lethal if made in error. Most cell fate decisions, including those of yeast, are understood as being triggered by the activation of master transcription factors. However, mechanisms that enforce cell fates posttranscriptionally have been more difficult to attain. Here, we perform a forward genetic screen to determine RNA-binding proteins that affect meiotic entry at the posttranscriptional level. Our screen revealed several candidates with meiotic entry phenotypes, the most significant being RIE1, which encodes an RRM-containing protein. We demonstrate that Rie1 binds RNA, is associated with the translational machinery, and acts posttranscriptionally to enhance protein levels of the master transcription factor Ime1 in sporulation conditions. We also identified a physical binding partner of Rie1, Sgn1, which is another RRM-containing protein that plays a role in timely Ime1 expression. We demonstrate that these proteins act independently of cell size regulation pathways to promote meiotic entry. We propose a model explaining how constitutively expressed RNA-binding proteins, such as Rie1 and Sgn1, can act in cell fate decisions both as switch-like enforcers and as repressors of spurious cell fate activation.