Dynein function at the vertebrate kinetochore

脊椎动物动粒的动力蛋白功能

• 批准号: 2107444
• 负责人: Steven Markus
• 金额: $ 109.53万
• 依托单位: Colorado State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2107444&HistoricalAwards=false
• 关键词: Dynein; function; vertebrate; kinetochore

Cell division (mitosis) is one of the most fundamental biological processes. It is remarkable as every division must take place with exceedingly high fidelity. Infidelity of the process leads to various afflictions, including cell death. Each cell’s duplicated genetic information – contained within chromosomes – must be equally (and faithfully) divided between the two daughter cells and the high degree of accuracy in this process is the consequence of a complex network of safety mechanisms that ensures mistakes are corrected prior to the completion of mitosis. The molecular machinery that ensures high-fidelity chromosome inheritance from mother to daughter cells includes an elaborate arrangement of filamentous structures called microtubules, and large protein-based structures assembled upon the chromosomes called kinetochores. Proper division of the genetic material requires that all duplicated chromosomes physically connect to microtubules through their kinetochores, allowing the chromosomes to become organized and aligned at the center of the cell in preparation for division. Kinetochores must make mechanically stable attachments to microtubules, and it is through these stable connections that duplicated sister chromosomes are both driven to the middle of the cell, then pulled apart towards the end of mitosis. Cells contain a monitoring system (a “checkpoint”) that prevents cells from exiting mitosis until all kinetochores are properly attached to microtubules such that they are poised to faithfully divide the chromosomes. While it is known that kinetochores monitor and regulate their own attachment status, how the attachment status of each kinetochore is relayed to the checkpoint machinery is unknown. The goals of this research project are to determine how a molecular motor, called dynein, affects and facilitates: (1) chromosome alignment, and (2) mitotic checkpoint signaling. The results from this project will have a significant impact on our understanding of mitotic cell division, and how the underlying molecular processes ensure it takes place with high fidelity. The Broader Impacts of the work include the inherent importance of this process to all multi-cellular life on the planet, together with outreach work that will be carried out at the community level and to elementary school students. The goal of this project is to understand how the microtubule motor protein dynein functions at kinetochores to promote faithful segregation of chromosomes during cell division. Cells possess complex mechanisms that ensure chromosome segregation occurs with remarkably high fidelity. During cell division, microtubules that comprise the mitotic spindle facilitate separation of sister chromatids through direct attachments to kinetochores, large macromolecular assemblies built upon centromeric DNA. Cells employ at least two critical mechanisms to minimize errors during this process: (A) The spindle assembly checkpoint prevents mitotic progression until all chromosomes have established proper kinetochore-microtubule attachments. Effectors of this checkpoint accumulate on improperly or unattached kinetochores, and consequently transmit a “wait anaphase” signal. Only upon establishment of proper attachments are these proteins evicted from kinetochores, which silences the inhibitory signal, thereby promoting anaphase onset. (B) The error correction pathway promotes the release of incorrect kinetochore-microtubule attachments, thereby allowing them to “reset” and form new, correct attachments. A key effector of both these processes is the microtubule motor protein dynein, which (1) transports checkpoint effectors away from kinetochores upon proper microtubule attachment, and (2) transports erroneously attached chromosomes to spindle poles, where they have a high likelihood of being corrected. The researchers will use a combination of in vitro and in-cell approaches to understand the role for dynein in both of these critical mitotic processes.This research is funded by the Cellular Dynamics and Function program in the Division of Molecular and Cellular Biosciences in the Directorate of Biological Sciences.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.

细胞分裂(有丝分裂)是最基本的生物学过程之一。这是值得注意的，因为每一次划分都必须以非常高的保真度进行。这一过程的不忠会导致各种痛苦，包括细胞死亡。每个细胞的复制遗传信息--包含在染色体中--必须在两个子细胞之间平均(且忠实地)分配，这一过程中的高度准确性是复杂的安全机制网络的结果，该网络确保在完成有丝分裂之前纠正错误。确保从母体细胞到子代细胞的高保真染色体遗传的分子机制包括一种称为微管的丝状结构的精心排列，以及组装在染色体上的称为动点的大型蛋白质结构。遗传物质的正确分裂需要所有复制的染色体通过它们的着丝点物理上连接到微管，使染色体变得有组织，并在细胞中心排列，为分裂做准备。动点必须在机械上稳定地附着在微管上，正是通过这些稳定的连接，复制的姐妹染色体都被驱动到细胞的中央，然后在有丝分裂结束时被撕裂。细胞包含一个监测系统(“检查点”)，它防止细胞退出有丝分裂，直到所有的动点都正确地附着在微管上，以便它们能够忠实地分裂染色体。虽然已经知道动粒监控和调节它们自己的附着状态，但每个动粒的附着状态是如何传递到检查点机器的还不清楚。这项研究项目的目标是确定一种名为动力蛋白的分子马达如何影响和促进：(1)染色体比对和(2)有丝分裂检查点信号。这个项目的结果将对我们理解有丝分裂细胞分裂以及潜在的分子过程如何确保它以高保真进行产生重大影响。这项工作的更广泛影响包括这一进程对地球上所有多细胞生命的内在重要性，以及将在社区一级和小学生一级开展的外联工作。这个项目的目标是了解微管运动蛋白dynein如何在运动中枢发挥作用，以促进细胞分裂过程中染色体的忠实分离。细胞拥有复杂的机制，确保染色体分离以非常高的保真度发生。在细胞分裂过程中，组成有丝分裂纺锤体的微管通过直接连接到着丝粒，即建立在着丝粒DNA上的大分子组件，促进姐妹染色单体的分离。细胞在这一过程中至少使用两种关键机制来减少错误：(A)纺锤体组装检查点阻止有丝分裂进行，直到所有染色体都建立了适当的动粒-微管连接。此检查点的效应器累积在不正确或未连接的运动中枢上，因此会发送“等待后期”信号。只有在建立了适当的附着后，这些蛋白质才会从动粒中被驱逐出去，从而抑制抑制信号，从而促进后期的开始。(B)纠错通路促进不正确的动粒-微管附着的释放，从而允许它们“重置”并形成新的、正确的附着。这两个过程的一个关键效应器是微管马达蛋白Dynein，它(1)在适当的微管连接时将检查点效应器从运动中枢转移出去，(2)将错误连接的染色体传输到纺锤体极，在那里它们很有可能被纠正。研究人员将使用体外和细胞内方法相结合的方法来了解动力蛋白在这两个关键有丝分裂过程中的作用。这项研究由生物科学局分子和细胞生物科学部门的细胞动力学和功能计划资助。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。