Timing and regulation of meiotic commitment

项目概要/摘要： 在减数分裂期间，二倍体细胞经历一轮复制，然后是两轮减数分裂。 染色体分离，最终产生单倍体配子。未能正确分离染色体 减数分裂中的异常可导致不育、流产和三体性病症，如唐氏综合症。尽管 减数分裂的重要性，缺乏对细胞周期调控网络的分子理解 在减数分裂I和减数分裂II中，确保染色体正确地附着在纺锤体微管上。的 该建议的目的是确定减数分裂调控机制，以确保正确的染色体 减数分裂分离。这些研究采用S.酿酒酵母作为模式生物，由于容易在 开发解决机械问题的工具。这些创新的工具将允许调查如何 细胞纠正不适当的微管-动粒附着，细胞如何设置减数分裂的持续时间，以及如何 沿着同源染色体交叉位置影响微管-动粒附着。的理由 对于拟议的研究是，选择的问题集中在过程中，很可能是高度 保守，允许芽殖酵母中的发现揭示减数分裂调控的一般机制。强 初步数据指导了以下三个具体目标：1）研究纺锤体检查点蛋白如何 与着丝粒上的激酶和磷酸酶相互作用，以调节染色体的时间和保真度 2）确定纺锤体检查点如何在减数分裂期间过早沉默， 染色体没有正确地附着在纺锤体微管上; 3）确定交叉位置 沿着染色体的一个小的突起可以影响着丝粒-微管附着的保真度。在第一个目标中， 将测试动粒上的调节剂在维持减数分裂的时间和准确性方面的作用。的 第二个目的是测试一种新的假设，即减数分裂特异性机制沉默纺锤体检查点， 确保配子的形成，即使没有适当的染色体分离。第三个目标涉及 长期未回答的问题，为什么在次优位置的染色体交叉更有可能 错误隔离。将开发出染色体经过改造以在特定位点形成交叉的菌株 位点和快速活细胞成像将监测与微管的附着。的创新做法 结合最新的成像技术来监测工程中的运动舞蹈微管附着， 菌株允许测试关于细胞周期调节的新假设。所提出的研究是有意义的 因为这些结果有望揭示减数分裂调控的一般原则， 基因组完整性最终，这些结果将进一步加深我们对减数分裂错误如何促进 发育异常

Project Summary/Abstract: During meiosis, a diploid cell undergoes one round of replication followed by two rounds of chromosome segregation to ultimately produce haploid gametes. A failure to properly segregate chromosomes in meiosis can result in infertility, miscarriage, and trisomy conditions, such as Down syndrome. Despite the importance of meiosis, there is a lack of molecular understanding of how cell-cycle regulatory networks function to ensure that chromosomes properly attach to spindle microtubules in meiosis I and meiosis II. The objective of this proposal is to determine the mechanisms of meiotic regulation that ensure proper chromosome segregation in meiosis. These studies employ S. cerevisiae as the model organism due to the ease in developing tools to address mechanistic questions. These innovative tools will allow the investigation of how cells correct improper microtubule-kinetochore attachments, how cells set the duration of meiosis, and how crossover position along homologous chromosomes affect microtubule-kinetochore attachments. The rationale for the proposed research is that the questions were chosen to focus on processes that are likely to be highly conserved, allowing the findings in budding yeast to uncover general mechanisms of meiotic regulation. Strong preliminary data guided the following three specific aims: 1) Investigate how spindle checkpoint proteins crosstalk with kinases and phosphatases at the kinetochore to regulate the timing and fidelity of chromosome segregation in meiosis; 2) Determine how the spindle checkpoint is prematurely silenced during meiosis when chromosomes are not correctly attached to spindle microtubules; and, 3) Determine how crossover location along a chromosome can affect the fidelity of kinetochore-microtubule attachments. In the first aim, cell-cycle regulators at the kinetochore will be tested for their role in maintaining the timing and accuracy of meiosis. The second aim tests the novel hypothesis of a meiosis-specific mechanism for silencing the spindle checkpoint to ensure the formation of gametes, even without proper chromosome segregation. The third aim addresses the long unanswered question of why chromosomes with crossovers at sub-optimal positions are more likely to mis-segregate. Strains will be developed that have chromosomes engineered to form a crossover at a specific site and fast live cell imaging will monitor the attachment to microtubules. The innovative approach of combining the latest imaging technologies to monitor kinetochore-microtubule attachments in engineered strains allows the testing of novel hypotheses about cell-cycle regulation. The proposed research is significant because the results are expected to reveal general principles of meiotic regulation important for protecting genome integrity. Ultimately, the results will further our understanding of how errors in meiosis facilitate developmental abnormalities.