Defining PP1 phosphatase function in paternal meiotic chromosome segregation

描述(申请人提供)：人类流产和智力低下的主要原因是染色体异常，这可能是由于卵母细胞或精子减数分裂过程中的染色体分离错误而产生的。绝大多数从头开始的染色体结构异常源于父系；因此，了解父系染色体分离机制对于预防自然和辅助生殖失败以及潜在的遗传性疾病向后代传播至关重要。我们已经鉴定出男性特异的PP1磷酸酶同源物，GSP-3和GSP-4，是已知的仅有的在从蠕虫到人类的精子形成中具有进化保守功能的蛋白质。我们的初步研究表明，在从减数分裂I向减数分裂II的转变过程中，这些磷酸酶提供了对染色体取向动态的性别特异性调节。GSP-3/4以类似于动粒蛋白的方式定位在精子减数分裂染色体周围，动粒蛋白是染色体和微管的关键连接点。我们还发现GSP-3/4调节特定动粒成分的性别特异性动态定位。因此，我们的假设是，这些PP1磷酸酶是纺锤体微管附着到染色质上的关键调节因子，因此在精子减数分裂过程中需要进行适当的染色体分割。我们将在三个主要领域验证我们的假设：1)MI到MII转变过程中的染色体定位和微管动力学，2)动粒成分的组成和动态定位，以及3)调节染色质-微管相互作用的因素的定位，以定位减数分裂纺锤体上的染色体。拟议的研究将确定精子减数分裂进程和父系染色质质量和含量的分子标记，这将进一步促进生殖和发育生物学领域的发展。我们的团队还将确定GSP-3/4在父系染色体分离特定阶段的作用和减数分裂的关键调控因素，为染色体生物学领域做出重大贡献。这项研究将为未来临床诊断和治疗的发展奠定基础，以识别或预防父系衍生的染色体异常，这是确保生殖成功和未来后代健康的关键一步。这些研究将包括SFSU的不同本科生和硕士研究生，SFSU是一所历史上为少数族裔服务的机构。我们预计，在三年的获奖期内，每年将有2-3名学生使用具有良好特性的试剂和新获得的尖端设备进行个人研究项目。因此，他们将获得实践、相关的研究经验和批判性思维技能，以进一步发展他们在生物医学科学领域的职业生涯。 公共卫生相关性：人类智力低下和流产的主要原因是在卵母细胞或精子减数分裂过程中产生的染色体异常。因此，确定控制父系减数分裂染色体分离的分子机制对于理解流产、不孕和唐氏综合症等出生缺陷的发生至关重要。这项研究将有助于消除在如何以性别特有的方式调节减数分裂染色体分离以确保生殖和发育成功的知识方面的相当大的差距。

DESCRIPTION (provided by applicant): The leading causes of miscarriage and mental retardation in humans are chromosomal abnormalities, which can be generated by chromosome segregation errors during oocyte or sperm meiosis. The vast majority of de novo chromosomal structural abnormalities are of paternal origin; thus, it is vital to understand paternal chromosome segregation mechanisms to prevent both natural and assisted reproductive failure and the potential transmission of genetic diseases to offspring. We have identified the male-specific PP1 phosphatase homologs, GSP-3 and GSP-4, as the only known proteins with evolutionarily conserved function specifically in sperm formation from worms to humans. Our preliminary studies suggest that these phosphatases provide sex-specific regulation of chromosome orientation dynamics during the transition from meiosis I to meiosis II. GSP-3/4 localizes around sperm meiotic chromosomes in a pattern similar to that of kinetochore proteins, key connectors of chromosomes and microtubules. We also find GSP-3/4 regulate the sex-specific dynamic localization of specific kinetochore components. Thus, our hypothesis is that these PP1 phosphatases are key regulators of spindle microtubule attachment to chromatin and thus required for proper chromosome partitioning during sperm meiosis. We will test our hypothesis in three main areas: 1) chromosome orientation and microtubule dynamics during the MI to MII transition, 2) composition and dynamic localization of components of the kinetochore, and 3) localization of factors that modulate chromatin-microtubule interactions to orient chromosomes on the meiotic spindle. The proposed studies will identify molecular markers for sperm meiotic progression and paternal chromatin quality and content, which will further the fields of reproductive and developmental biology. Our team will also define the role of GSP-3/4 and key regulators of meiosis at specific stages of paternal chromosome segregation, making a significant contribution to the field of chromosome biology. This research will lay the groundwork for future development of clinical diagnostics and therapies to identify or prevent paternally-derived chromosomal abnormalities, a vital step to ensuring reproductive success and the health of future offspring. These studies will incorporate the diverse undergraduate and master's level students at SFSU, a historically minority-serving institution. We anticipate 2-3 students per year will conduct individual research projects using well-characterized reagents and assays with newly acquired cutting-edge equipment during the three-year award period. As such, they will gain hands-on, relevant research experience and critical thinking skills to further their careers in the biomedical sciences. PUBLIC HEALTH RELEVANCE: The leading causes of mental retardation and miscarriages in humans are chromosomal abnormalities generated during either oocyte or sperm meiosis. Determining the molecular mechanisms that govern paternal meiotic chromosome segregation is thus crucial to understanding how miscarriage, infertility, and birth defects like Down's Syndrome arise. This study will contribute to the eliminating a considerable gap in knowledge in how meiotic chromosome segregation is regulated in sex-specific ways to ensure reproductive and developmental success.