Investigate the Molecular Basis that Controls the Timing of Spindle Elongation

描述（由申请人提供）：染色体错误分离是遗传性疾病的常见原因，包括出生缺陷和癌症。纺锤体的伸长是染色体分离的必要条件，纺锤体过早伸长会导致染色体异常分离。因此，必须正确地调节锭子伸长的时机。本申请的目的是确定细胞如何确保纺锤体伸长在正确的时间发生。本申请的中心假设是，在芽殖酵母中，有丝分裂CDK（细胞周期蛋白依赖性激酶）与S期CDK的平衡控制纺锤体伸长的时机。S期CDK通过磷酸化S期CDK特异性底物在纺锤体延伸中起负作用，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延伸。Cdc14磷酸酶负责S期CDK底物的去磷酸化，而有丝分裂CDK通过激活FEAR（Cdc14早期后期释放）（一种在后期早期将Cdc14从核仁释放的有丝分裂退出途径）来实现这一点。我们进一步提出，S期CDK抑制纺锤体延长通过磷酸化Spc110，一个组件的纺锤体极体（SPB）。我们将采取全面的生物化学，遗传学和功能的方法来研究芽殖酵母纺锤体伸长的时间控制。申请的目标将通过追求三个具体目标来实现。1)检验S期和有丝分裂期CDKs拮抗性调节纺锤体伸长的假设。2)检验有丝分裂期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)我们推测S期CDK通过磷酸化Spc110（纺锤体的一个组成部分）抑制纺锤体的伸长。这项工作是创新的，因为它将揭示控制纺锤体伸长时间的分子基础。我们预期，细胞周期中有丝分裂期和S期CDK的严格调节的活性确保了纺锤体伸长的正确时机。这些结果将是重要的，因为新的知识将为预防遗传疾病（如癌症）提供新的靶点。此外，这项R15提案的支持将使本科生的培训和接触他们的生物医学研究。 公共卫生相关性：在有丝分裂过程中，纺锤体伸长将复制的染色体分离成两个子细胞。纺锤体过早伸长导致异常染色体分离，这是许多癌细胞的特征。这项提议旨在了解控制纺锤体伸长时间的分子基础。因此，这项研究可能会发现癌症诊断和治疗的新靶点。此外，许多本科生将通过参与该项目接受生物医学研究方面的培训。

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.