Meiotic Cdc7 Substrates and Regulation of NDT80 Transcription

真核生物利用两种类型的细胞分裂。有丝分裂产生基因相同的子细胞， 从而为生长分化提供原料。相反，减数分裂将 细胞的染色体数目减半，产生含有新的等位基因组合的单倍体配子。 当两个配子融合时，这种减少对于保持染色体数目的恒定是必不可少的。 受精。有丝分裂和减数分裂有许多共同的特征：例如，染色体是 使用基于微管的纺锤体进行分离，姐妹染色单体由粘附素结合在一起，以及 粘附素的破坏也是通过同样的蛋白分解机制进行的。几个特定于减数分裂的过程 然而，进化到允许在一轮DNA复制后发生两个分裂，从而 同源染色体，而不是姐妹染色单体，在减数分裂I时脱离到相反的两极。这些 包括通过交叉和凝聚相结合的方式连接同源染色体， 减数分裂I和减数分裂II两步去除粘连蛋白的时间差异和姐妹细胞的单向性 减数分裂的动点I.最近的研究表明，这些减数分裂特有的过程是由 减数分裂特异蛋白和有丝分裂细胞周期蛋白激酶如CDK、CDC5和CDC7之间的相互作用。 利用CDC7的模拟敏感条件等位基因CDC7-AS，我的实验室已经证明CDC7对于减数分裂重组、姐妹着丝点的单向性和减数分裂进程是必不可少的。这笔赠款的目的是使用生化、遗传学和基因组学方法来了解CDC7如何在分子水平上调节减数分裂过程。在目标1中，我们将使用最近开发的用于模拟敏感激酶的新策略来鉴定CDC7的减数分裂底物。在目标2中，我们将研究CDC7如何调节NDTSO的表达，NDTSO是一种减数分裂特异的转录因子，它起着分子开关的作用，允许粗线期退出、减数分裂进程和单倍体产物分化为孢子。

Eukaryotic organisms utilize two types of cell division. Mitosis creates genetically identical daughter cells, thereby providing the raw material for growth and differentiation. Meiosis, in contrast, divides the chromosome number of cells in half, producing haploid gametes containing new combinations of alleles. This reduction is essential in keeping the chromosome number constant when two gametes fuse at fertilization. Mitosis and meiosis share many features in common: for example, chromosomes are segregated using microtubule based spindles, sister chromatids are held together by cohesins, and destruction of cohesins occurs via the same proteolytic machinery. Several meiosis-specific processes have evolved, however, to allow two divisions to occur after a single round of DNA replication such that homologous chromosomes, instead of sister chromatids, disjoin to opposite poles at Meiosis I. These include the connection of homologous chromosomes by a combination of crossing over and cohesion, the temporally distinct two step removal of cohesins at Meiosis I and Meiosis II and the mono-orientation of sister kinetochores at Meiosis I. Recent work has shown that these meiosis-specific processes result from the interplay between meiosis-specific proteins and mitotic cell cycle kinases such as CDK, Cdc5 and Cdc7. Using an analog sensitive conditional allele of CDC7, cdc7-as, my lab has shown that CDC7 is essential for meiotic recombination, mono-orientation of sister kinetochores and meiotic progression. The purpose of this grant is to use biochemical, genetic and genomic approaches to understand how Cdc7 regulates meiotic processes at the molecular level. In Aim 1, we will identify meiotic substrates of Cdc7 using novel strategies recently developed for use with analog sensitive kinases. In Aim 2, we will investigate how Cdc7 regulates the expression of NDTSO, a meiosis-specific transcription factor that acts a molecular switch to allow exit from pachytene, meiotic progression and differentiation of haploid products into spores.