Investigate the Molecular Basis that Controls the Timing of Spindle Elongation

描述（由申请人提供）：染色体错分离是遗传疾病的常见原因，包括出生缺陷和癌症。纺锤体伸长是染色体分离的必要条件，过早的纺锤体伸长会导致染色体分离异常。因此，主轴延伸的时间必须正确调节。这个应用程序的目的是确定细胞如何确保纺锤体伸长发生在正确的时间。该应用程序的中心假设是，在出芽酵母中，有丝分裂CDK（周期蛋白依赖激酶）与s期CDK的平衡控制纺锤体伸长的时间。S期CDK通过磷酸化S期CDK特异性底物对纺锤体伸长起负作用，而有丝分裂CDK通过间接刺激S期CDK底物的去磷酸化来促进纺锤体伸长。Cdc14磷酸酶负责s期CDK底物的去磷酸化，有丝分裂的CDK通过激活FEAR （Cdc 14早期后期释放）来实现这一过程，这是一种有丝分裂的退出途径，在早期后期将Cdc14从核核中释放出来。我们进一步提出，s期CDK通过磷酸化sp110抑制纺锤体伸长，SPB是纺锤体极体的一个组成部分。我们将采取全面的生化，遗传和功能的方法来研究芽殖酵母纺锤体伸长的时间控制。应用程序的目标将通过追求三个具体目标来实现。1)验证s期和有丝分裂CDKs拮抗调节纺锤体伸长的假设。2)验证有丝分裂CDK激活FEAR通路以抵消s期CDK对纺锤体伸长的负面影响的假设。3)我们假设s期CDK通过磷酸化sp110（纺锤极体的一个组成部分）来抑制纺锤体伸长。提出的工作是创新的，因为它将揭示控制纺锤体伸长时间的分子基础。我们期望在细胞周期中有丝分裂和s期CDK的严格调控活动确保纺锤体伸长的正确时间。这些成果将具有重大意义，因为新的知识将为预防遗传疾病（如癌症）提出新的目标。此外，这项R15提案的支持将有助于培养本科生并使他们接触生物医学研究。

DESCRIPTION (provided by applicant): Chromosome mis-segregation is a common cause of genetic disorders, including birth defects and cancer. Spindle elongation is essential for chromosome segregation and premature spindle elongation leads to abnormal chromosome segregation. Thus, the timing of spindle elongation must be rightly regulated. The objective of this application is to determine how cells ensure that spindle elongation occurs at the right time. The central hypothesis of the application is that, in budding yeast, the balance of mitotic CDK (cyclin dependent kinase) vs. S-phase CDK controls the timing of spindle elongation. S- phase CDK plays a negative role in spindle elongation by phosphorylating the S-phase CDK-specific substrates, whereas mitotic CDK promotes spindle elongation by indirectly stimulating the dephosphorylation of S-phase CDK substrates. The Cdc14 phosphatase is responsible for the dephosphorylation of S-phase CDK substrates and mitotic CDK allows this to happen by activating the FEAR (Cdc Fourteen Early Anaphase Release), a mitotic exit pathway that frees Cdc14 from the nucleolus during early anaphase. We further propose that S-phase CDK inhibits spindle elongation through the phosphorylation of Spc110, a component of the spindle pole body (SPB). We will take a comprehensive biochemical, genetic, and functional approach to study the timing control of spindle elongation in budding yeast. The objective of the application will be accomplished by pursuing three specific aims. 1) Test the hypothesis that S-phase and mitotic CDKs antagonistically regulate spindle elongation. 2) Test the hypothesis that mitotic CDK activates the FEAR pathway to counteract the negative effect of S-phase CDK on spindle elongation. 3) We hypothesize that S-phase CDK inhibits spindle elongation by phosphorylating Spc110, a component of the spindle pole body. The proposed work is innovative because it will reveal the molecular basis that controls the timing of spindle elongation. It is our expectation that the tightly regulated activities of mitotic and S-phase CDK during cell cycle ensure the correct timing of spindle elongation. Such outcomes will be significant because new knowledge will suggest new targets for preventing genetic disorders, such as cancer. Moreover, the support of this R15 proposal will enable the training of undergraduate students and expose them to biomedical research. PUBLIC HEALTH RELEVANCE: During mitosis, spindle elongation segregates duplicated chromosomes into two daughter cells. Premature spindle elongation leads to abnormal chromosome segregation, a characteristic of many cancer cells. This proposal aims to understand the molecular basis that controls the timing of spindle elongation. Therefore, this research will potentially uncover new targets for cancer diagnosis and treatment. Moreover, many undergraduate students will receive training in biomedical research by working on this project.