Control of Genomic Stability by Emil and Secruin

描述（由申请人提供）：非整倍体和染色体畸变是人类神经质的共同特征。基因组不稳定，或有丝分裂错误导致染色体复制、丢失和易位的倾向，长期以来被认为是肿瘤发生的主要机制。对基因组不稳定性的研究有望为癌症治疗提供新的见解。近年来，对有丝分裂调控的分子细节的理解取得了重大进展。Securin是一种蛋白质，其功能是通过抑制后期进程，直到所有染色体在中期正确排列，以确保染色体准确分布到子细胞。当细胞过度或过少表达securin时，它们会产生染色体异常和微核。这种微核常见于神经肿瘤，尤其是少性腺胶质瘤。另一种蛋白质，Emi1，最近被彼得·杰克逊实验室发现，参与S期激活和有丝分裂控制。Emi1通过抑制securin的泛素化来阻止其降解，但也直接与securin结合。过表达Emi1会导致前期异常阻滞和有丝分裂纺锤体异常形成。我们假设Emi1和securin的直接相互作用介导了这种导致基因组不稳定的效应。Hct116结肠癌细胞是二倍体细胞系，是有丝分裂研究的理想细胞系。我将以这些细胞为工具，研究Emi1和securin对基因组稳定性的控制。我还将讨论Emi1和securin在神经肿瘤发生中的可能作用。拟议的研究将具体解决以下问题。内源性Emi1和secure是否在细胞中直接相互作用，如果是，在细胞周期的哪个阶段？Emi1-securin相互作用是否局限于细胞内？Emi1和securin的哪些功能域在确定它们的相互作用方面是重要的？Emi1错误表达是否会导致纺锤体异常或染色体错误分离？这种影响是否需要安全性？Emi1的过表达或过低表达是否会产生染色体畸变，如缺失或重复？如果有，是否有特定的细胞遗传学异常发生？Emi1过表达是诱导细胞转化，还是与ras、myc或securin等已知癌基因协同诱导细胞转化？Emi1错误表达是否发生在特定的肿瘤类型中，包括神经系统肿瘤？肿瘤中Emi1表达与securin表达呈正相关还是负相关？肿瘤中Emi1或securin表达是否与细胞周期蛋白D/Rb/E2F通路的激活相关？我将继续从事神经病理学方面的学术工作，并将从拟议的研究中获得的知识和经验应用于转化神经肿瘤学研究。

DESCRIPTION (provided by applicant): Aneuploidy and chromosomal aberrations are common features of human neuroplasms. Genomic instability, or the tendency for mitotic errors to create chromosomal duplications, losses, and translocations has long been recognized as a major mechanism of tumorigenesis. The study of genomic instability promises new insights into cancer treatment. Recently, significant advances have been made in the understanding of the molecular details of the regulation of mitosis. Securin is a protein that functions to ensure accurate distribution of chromosomes to daughter cells by inhibiting anaphase progression until all chromosomes are properly aligned at metaphase. When cells are manipulated to over-or under-express securin they develop chromosomal abnormalities and micronuclei. Such micronuclei are frequently seen in neurological tumors, especially oligogendrogliomas. Another protein, Emi1, recently discovered by the Peter Jackson Laboratory, is involved in S phase activation and mitotic control. Emi1 blocks the degradation of securin by inhibiting its ubiquitination, but also directly binds to securin. Over-expression of Emi1 causes an abnormal prometaphase block and abnormal mitotic spindle formation. We hypothesize that the direct interaction of Emi1 and securin mediates this effect causing genomic instability. Hct116 colon carcinoma cells are a diploid cell line ideal for mitotic studies. I will use these cells as a tool to study the control of genomic stability by Emi1 and securin. I will also address the possible role of Emi1 and securin in the genesis of neurological tumors. The proposed research will specifically address the following questions. Do endogenous Emi1 and securing interact directly in cells, and if so, during which stage(s) of the cell cycle? Is the Emi1-securin interaction localized within the cell? Which functional domains of Emi1 and securin are important in determining their interaction? Does Emi1 misexpression cause spindle abnormalities or chromosomal missegregation, and is securin required for this effect? Does over- or under-expression of Emi1 produce chromosomal aberrations such as deletions or duplications? If so, do specific cytogenetic abnormalities occur? Does Emi1 over-expression induce cellular transformation, or cooperate with known oncogenes such as ras, myc, or securin, in inducing transformation? Does Emi1 misexpression occur in specific tumor types, including neurological tumors? Does Emi1 expression positively or negatively correlate with securin expression in tumors? Does Emi1 or securin expression correlate with activation of the cyclin D/Rb/E2F pathway in tumors? I will pursue an academic career in neuropathology and will apply the knowledge and experience gained from the proposed studies to translational neuro-oncology research.