权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Formin mDia Functions in Mitosis

Formin mDia 在有丝分裂中的功能

基本信息

批准号：
8917249
负责人：
Yinghui Mao
金额：
$ 30.35万
依托单位：
COLUMBIA UNIVERSITY HEALTH SCIENCES
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-09-30 至 2016-12-31
项目状态：
已结题

项目摘要

DESCRIPTION (provided by applicant): Accurate delivery of one copy of each chromosome in mitosis is essential for faithful transmission of genetic information during each cell division. Errors in this process result in abnormal numbers of chromosomes (a condition described as aneuploidy), which early in development lead to lethal developmental defects and later are hallmarks of human tumor progression. Proper chromosome segregation requires that each chromosome is bi-oriented with one kinetochore attaches to microtubules from one pole of a bipolar spindle while the other sister kinetochore is attached to microtubules from the opposite pole. Improper chromosome attachments, such as synthetic and merotelic attachments, frequently occur in mitosis. A long standing question in the mitosis field is how cells achieve proper stable end-on kinetochore microtubule attachment. Using mammalian cultured cells and purified components in vitro, we intend to determine how formin mDia3 plays a novel role at kinetochores in contribute to stable microtubule attachment. We have shown that knockdown of mDia3 in mammalian cultured cells using siRNA results in defects in metaphase chromosome alignment and stable kinetochore microtubule attachment. These defects can be rescued by a siRNA-resistant wild-type mDia3 construct and mDia3 mutants that are defective in actin nucleation, but not in microtubule stabilization. We have further shown that mDia3 is phosphorylated by Aurora B kinase in vitro and expression of a non- phosphorylatable mDia3 mutant in cells had a chromosome misalignment phenotype. Using microtubule- binding- and EB1-binding-deficient mDia3 mutants for rescue of mDia3 siRNA depletion phenotypes, we will determine whether mDia3 at the kinetochore could act directly by its microtubule activity or indirectly via its interaction partners, EB1 and APC, in contributing to stable kinetochore microtubule attachment. We will use microtubule co-sedimentation analysis with purified components to determine whether stably binding of mDia3, along with EB1 and APC, to the microtubule lattice influences the microtubule binding affinity of the Ndc80 complex, which has been implicated as a core microtubule binding force at the kinetochore. Using immunofluorescence analysis and live cell imaging, we will continue to determine whether Aurora B phosphorylation of mDia3 may represent part of the mechanism for correction of microtubule attachment errors. We will examine how Aurora B phosphorylation affects mDia3 microtubule binding and stabilization activities in vitro using purified components. We will also examine the mitotic phenotypes resulted from the expression of either the non-phosphorylatable or the phosphomimetic mDia3 mutants.

描述（由申请人提供）：在有丝分裂中准确递送每条染色体的一个拷贝对于在每次细胞分裂期间忠实地传递遗传信息至关重要。这一过程中的错误导致染色体数量异常（一种被描述为非整倍性的情况），在发育早期导致致命的发育缺陷，后来成为人类肿瘤进展的标志。正确的染色体分离要求每条染色体都是双向的，其中一个动粒附着在双极纺锤体的一极的微管上，而另一个姐妹动粒附着在另一极的微管上。不正确的染色体附着，如合成的和不完全的附着，经常发生在有丝分裂中。有丝分裂领域的一个长期存在的问题是细胞如何实现适当的稳定的端对动粒微管附着。使用体外培养的哺乳动物细胞和纯化的成分，我们打算确定如何在着丝粒中发挥新的作用，促进稳定的微管附着。我们已经表明，在哺乳动物培养细胞中使用siRNA敲低mDia3导致中期染色体排列和稳定的动粒微管附着缺陷。这些缺陷可以通过siRNA抗性野生型mDia3构建体和在肌动蛋白成核方面有缺陷但在微管稳定方面没有缺陷的mDia3突变体来挽救。我们进一步表明mDia3在体外被Aurora B激酶磷酸化，并且细胞中不可磷酸化的mDia3突变体的表达具有染色体错配表型。使用微管结合缺陷型和EB 1结合缺陷型mDia3突变体来拯救mDia3 siRNA耗竭表型，我们将确定mDia3在动粒处是否可以通过其微管活性直接作用或通过其相互作用配偶体EB 1和APC间接作用，从而有助于稳定的动粒微管附着。我们将使用纯化组分的微管共沉淀分析来确定mDia3与EB 1和APC沿着与微管晶格的稳定结合是否影响Ndc80复合物的微管结合亲和力，Ndc80复合物被认为是着丝粒处的核心微管结合力。使用免疫荧光分析和活细胞成像，我们将继续确定mDia3的Aurora B磷酸化是否可能代表微管附着错误纠正机制的一部分。我们将研究如何极光B磷酸化影响mDia3微管结合和稳定活动在体外使用纯化的组件。我们还将检查由非磷酸化或磷酸化模拟mDia3突变体的表达引起的有丝分裂表型。