Differentiation in Yeast: Mechanisms of Mating and Meiosis

真核细胞在受精过程中融合，产生二倍体受精卵，这些受精卵继续分化为特化 发育过程中的细胞。体细胞融合也发生在发育过程中以产生多核细胞 组织，如成肌细胞融合形成肌肉。二倍体生物随后可能经历减数分裂以产生 单倍体配子用于随后的受精，完成有性繁殖的循环。细胞融合和 减数分裂必须受到严格的调控。不适当的细胞融合，就像发生在一些病毒感染的细胞和 转移性癌症，导致病理性合胞体。尽管在阐明细胞融合过程方面取得了进展， 还有很多事情是未知的。减数分裂缺陷可能导致非整倍体，甚至不育。最近的研究表明 这种减数分裂调控令人惊讶地复杂。覆盖在转录调控波上的是复杂的 一层层的mRNA修饰和翻译调节，被认为提供了精致的时间 控制力。然而，关于减数分裂是如何调控的，仍有许多有待了解。中国的长期目标是 我实验室的研究是为了了解细胞融合、核融合的基本、保守的分子机制 融合，以及利用最强大的模式生物之一的发芽酵母进行减数分裂调控 酿酒酵母。在酵母交配和体细胞融合过程中，细胞必须发出信号，表明它们处于 接触并有能力融合，去除分离它们的细胞外基质，并融合血浆 膜。人们对每一步都知之甚少。我们已经证明了在酵母中，就像在小鼠成肌细胞中一样， CDC42P是细胞融合的关键调控因子。我们将讨论细胞接触如何调节cdc42p，以及cdc42p如何进入 TURN介导细胞融合，侧重于细胞膜弯曲和细胞壁完整性途径。用一本小说 在基因筛选中，我们将继续进行酵母膜FusoGen的鉴定。交配和细胞融合后， 许多诱导的蛋白质可能是危险的，必须迅速降解。我们发现，Sr14P稳定 交配通过抑制蛋白酶体降解途径的一个分支来诱导蛋白质。我们将研究如何 在交配和有丝分裂过程中，srl4p对蛋白质的周转起着不同的调节作用。在许多受精后 生物体，原核融合。核聚变是一个具有挑战性的生物学问题--这两种膜是如何 熔断器是否按顺序和寄存器？我们鉴定了Kar5p，一种在植物、动物和真菌中保守的蛋白质，是 调节核包膜融合；然而，它的确切作用尚不清楚。我们将检验我们的假设，即Kar5p 作为一种新颖的内核膜FusoGen。在减数分裂中，已经发现了N6-腺嘌呤基因的甲基化 作为一个关键的监管者，尽管其职能尚不清楚。Kar4p是人类的酵母同系物 甲基转移酶的核心成分METTL14。令人惊讶的是，我们发现Kar4p对两者都有调节作用 减数分裂转录和减数分裂蛋白水平。我们将研究Kar4p如何在多种情况下调节减数分裂 水平，测试转录、翻译调控和信使核糖核酸修饰的潜在作用。我们的研究将 有助于理解细胞融合、核膜融合和减数分裂的基本保守机制。

Eukaryotic cells fuse during fertilization to produce diploid zygotes that go on to differentiate into specialized cells during development. Somatic cell fusion also occurs during development to produce multinucleate tissues, such as myoblast fusion to form muscle. Diploid organisms may then undergo meiosis to produce haploid gametes for subsequent fertilization, completing the cycle of sexual reproduction. Cell fusion and meiosis must be tightly regulated. Inappropriate cell fusion, as occurs in some virally-infected cells and metastatic cancers, results in pathological syncytia. Despite advances in elucidating the process of cell fusion, much remains unknown. Meiotic defects may cause aneuploidy, or even sterility. Recent research revealed that meiotic regulation is surprisingly complex. Overlaid on waves of transcriptional regulation are complex layers of mRNA modification and translational regulation which are thought to provide exquisite temporal control. However, much remains to be learned about how meiosis is regulated. The long-term goals of the research in my lab are to understand the fundamental, conserved molecular mechanisms of cell fusion, nuclear fusion, and meiotic regulation using one of the most powerful model organisms, the budding yeast Saccharomyces cerevisiae. During yeast mating and somatic cell fusion, cells must signal that they are in contact and competent to fuse, remove the extracellular matrix separating them, and fuse the plasma membranes. Each step is only poorly understood. We have shown that in yeast, as in mouse myoblasts, Cdc42p is a key regulator of cell fusion. We will address how cell contact regulates Cdc42p and how Cdc42p in turn mediates cell fusion, focusing on membrane curvature and the cell wall integrity pathway. Using a novel genetic screen, we will pursue identification of the yeast membrane fusogen. After mating and cell fusion, many induced proteins may be hazardous and must be rapidly degraded. We discovered that Srl4p stabilizes mating-induced proteins by inhibiting a branch of the proteasomal degradation pathway. We will examine how Srl4p differentially regulates the turnover of proteins in mating and mitosis. After fertilization in many organisms, the pronuclei fuse. Nuclear fusion is a challenging biological problem – how do the two membranes fuse sequentially and in register? We identified Kar5p, a protein conserved in plants, animals, and fungi, as mediating nuclear envelope fusion; however, its precise role is unknown. We will test our hypothesis that Kar5p acts as a novel inner nuclear envelope fusogen. In meiosis, mRNA N6-adenine methylation has been revealed to be a critical regulator, although its functions are not yet understood. Kar4p is the yeast homologue of human METTL14, a core component of the methyl-transferase. Surprisingly, we found that Kar4p regulates both meiotic transcription and meiotic protein levels. We will examine how Kar4p regulates meiosis at multiple levels, testing potential roles in transcription, translational regulation, and mRNA modification. Our studies will aid the understanding of basic conserved mechanisms of cell fusion, nuclear membrane fusion, and meiosis.