Investigate the Molecular Basis that Controls the Timing of Spindle Elongation

描述(申请人提供)：染色体错误分离是遗传疾病的常见原因，包括出生缺陷和癌症。纺锤体的伸长是染色体分离的关键，过早的纺锤体伸长会导致染色体的异常分离。因此，必须正确调整主轴伸长的时间。这项应用的目标是确定细胞如何确保纺锤体在正确的时间发生伸长。这项应用的中心假设是，在萌芽酵母中，有丝分裂CDK(细胞周期蛋白依赖激酶)与S期CDK的平衡控制着纺锤体延长的时间。S期CDK通过磷酸化S期CDK特异性底物促进纺锤体的伸长，而有丝分裂CDK通过间接刺激S期CDK底物的去磷酸化而促进纺锤体的伸长。CDC14磷酸酶负责S相CDK底物的去磷酸化，有丝分裂CDK通过激活恐惧(CDC14早期后期释放)来实现这一过程，这是有丝分裂退出途径，在早期后期将CDC14从核仁中释放出来。我们进一步提出，S期细胞周期蛋白依赖性蛋白激酶通过对纺锤体极体的一种成分Spc110的磷酸化来抑制纺锤体的延长。我们将采取综合的生化、遗传和功能方法来研究芽期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)验证S期和有丝分裂CDKs拮抗调节纺锤体伸长的假说。2)验证有丝分裂CDK激活恐惧通路以对抗S期CDK对纺锤体伸长的负面影响的假说。3)我们推测，S期细胞周期蛋白依赖性蛋白激酶通过磷酸化纺锤体极体成分Spc110抑制纺锤体的伸长。这项拟议的工作具有创新性，因为它将揭示控制纺锤体伸长时间的分子基础。我们预计，细胞周期中有丝分裂和S期CDK的活性受到严格调控，从而确保纺锤体伸长的正确时机。这样的结果将是重要的，因为新的知识将为预防癌症等遗传疾病提供新的目标。此外，R15提案的支持将使本科生能够接受培训，并使他们接触到生物医学研究。 与公共卫生相关：在有丝分裂过程中，纺锤体的伸长将复制的染色体分离成两个子细胞。纺锤体过早延长会导致染色体异常分离，这是许多癌细胞的特征。这项建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这个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.