Harnessing evolution to reveal the molecular logic of kinetochore wiring

这个项目关注的是遗传物质被分配到形成的每个新细胞的基本过程。由于单个人类细胞中的DNA大约有6英尺长，它必须被包装成称为染色体的物理单位。每次细胞分裂时，这些染色体必须复制并忠实地分配到每个新细胞中。在人类的一生中，这种情况肯定会发生数万亿次。为了促进这一过程，哺乳动物细胞形成了一种称为“着丝点”的分子机器，它可以识别每条染色体，并将这些染色体物理地分离到新形成的细胞中。当这种分配机制出现缺陷时，关键的遗传物质就会丢失或被破坏，对这些细胞的功能和生存能力造成严重后果。因此，了解着丝点的组装和功能是至关重要的。然而，关于着丝点的性质、功能和进化，仍有大量悬而未决的问题。该项目将探索哺乳动物中着丝点机器的变化，并利用进化差异来对这台机器的功能和适应不同要求的方式产生新的理解。该项目的更广泛影响将包括对本科生、研究生和博士后研究人员以及一名高中教师进行研究方法方面的培训。真核生物的染色体分离需要着丝点，这是一种连接染色体和微管聚合物的大分子结构，为染色体的运动提供动力。尽管在指导染色体分离方面有保守的要求，但在真核生物中，着丝点在其结构、组成和组织方面具有显著的灵活性。这个项目将利用着丝点的进化可塑性来探索着丝点组装和功能的分子逻辑。特别是，该项目将测试在哺乳动物物种中，着丝点蛋白序列、组成和需求的变化是否代表了进化驱动的机制，这些机制优化了基本相似的着丝点活动，以满足不同的生理限制。通过探索这一想法，本研究试图产生一个连贯的分子模型，以了解着丝点组分如何单独作用，并以综合的方式以稳健和保守的方式实现忠实的染色体分离，并根据每个物种的特定要求进行定制。总之，该项目将定义着丝点连接的逻辑，揭示关键着丝点支架的组成，着丝点-微管界面的特性，以及如何在进化过程中调节这些以达到最佳结果。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This project focuses on the fundamental processes by which the genetic material is distributed to each new cell that is formed. As the DNA in a single human cell is approximately 6 feet long, it must be packaged into physical units termed chromosomes. Every time a cell divides, these chromosomes must be duplicated and faithfully distributed to each new cell. Over the course of a lifetime in humans, this must occur trillions of times. To facilitate this, mammalian cells form a molecular machine – called the “kinetochore” - that recognizes each chromosome and physically segregates these chromosomes to the newly formed cells. When this distribution machinery is defective, critical genetic material can be lost or disrupted, with serious consequences to the function and viability of those cells. Thus, it is critical to understand how kinetochores assemble and function. However, there are substantial open questions regarding the nature, function, and evolution of kinetochores. This project will explore the changes to the kinetochore machine across mammals and use evolutionary differences to create a new understanding of the way in which this machine functions and adapts to differing requirements. The Broader Impacts of the project will include the training of undergraduates, graduate students and post-doctoral researchers, along with a high-school teacher in research methodologies.Eukaryotic chromosome segregation requires the kinetochore, the macromolecular structure that connects chromosomes to the microtubule polymers, which power their movement. Despite a conserved requirement in directing chromosome segregation, the kinetochore is remarkably flexible in its structure, composition, and organization across eukaryotes. This project will harness kinetochore evolutionary plasticity to probe the molecular logic by which kinetochores assemble and function. In particular, this project will test whether changes to kinetochore protein sequences, composition, and requirements across mammalian species represent evolutionary-driven mechanisms that optimize fundamentally similar kinetochore activities to meet diverse physiological constraints. By exploring this idea, this research seeks to generate a coherent molecular model for how kinetochore components act individually and in an integrated manner to achieve faithful chromosome segregation in a way that is robust and conserved, and yet tailored to the specific requirements of each species. Together, this project will define the logic of kinetochore wiring, reveal the composition of the critical kinetochore scaffold, the properties of the kinetochore-microtubule interface, and how these are modulated across evolution to achieve an optimal outcome.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.