BUBRI in Normal and Neoplastic Growth

正常和肿瘤生长中的 BUBRI

• 批准号: 6909862
• 负责人: JAN M. VAN DEURSEN
• 金额: $ 28.94万
• 依托单位: MAYO CLINIC ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6909862
• 关键词: cancer risk; cell cycle; cell cycle proteins; cell line; chromosome aberrations; genetically modified animals; laboratory mouse; mitotic spindle apparatus; molecular oncology; neoplasm /cancer genetics; neoplastic growth; protein structure function

DESCRIPTION (provided by applicant): Abnormalities of chromosome number are a hallmark of the vast majority of human cancers. A subset of these cancers is associated with mutations in genes encoding for mitotic checkpoint proteins such as BUB1, BUBR1 or MAD2. These checkpoint proteins are part of an intricate regulatory mechanism that prevents aneuploidy by delaying sister chromatid separation until all chromosomes are properly attached to the mitotic spindle apparatus and aligned at the metaphase plate. Therefore, they may contribute to chromosomal instability when defective. Initial attempts to study the possible connection between mitotic checkpoint dysfunction and disease by classical gene knockout approaches in the mouse have been hampered by the early embryonic death of mice lacking BUB3 or MAD2. In an effort to generate a mouse model for mitotic checkpoint dysfunction, we generated mice with a hypomorphic BUBR1 allele (BUBR1 hypo). Mice homozygous for the hypomorphic BUBR1 allele are viable despite a strong reduction of their BUBR 1 protein levels. Preliminary data demonstrate the formation of histological confirmed tumors in several homozygous mutant mice. Detailed analyses of early-passage fibroblasts derived from 13.5-day-old homozygous mutant embryos show that the diminished BUBR1 expression causes premature sister chromatid separation and aneuploidy. In this project we have proposed experiments to elucidate the biological role of BUBR1, and the mechanisms by which BUBR1 dysfunction may lead to malignant cell transformation. In specific aim one, we will use inducible BUBR1 knockout cell lines to establish the in vivo role of BUBR1 and its critical functional domains. In specific aim two, we will determine the rates of spontaneous and carcinogen-induced tumor formation in hypomorphic BUBR1 mice, and investigate the effect of BUBR1 dysfunction on chromosomal instability at the organismal level. In specific aim three, we will identify the tumorigenic pathways able to cooperate with BUBR1 in the formation of tumors. Together these studies will provide valuable insights into the normal function of BUBR1 and help to elucidate how errors in the control of the mitotic spindle assembly checkpoint lead to increased susceptibility to tumor formation.

描述（申请人提供）：染色体数目异常是绝大多数人类癌症的标志。这些癌症的一个子集与编码有丝分裂检查点蛋白（如BUB1、BUBR1或MAD 2）的基因突变相关。这些检查点蛋白是一个复杂的调控机制的一部分，通过延迟姐妹染色单体分离，直到所有染色体正确地连接到有丝分裂纺锤体装置，并在中期板对齐，防止非整倍性。因此，当它们有缺陷时，可能会导致染色体不稳定。通过经典基因敲除方法在小鼠中研究有丝分裂检查点功能障碍与疾病之间可能的联系的初步尝试受到缺乏BUB3或MAD 2的小鼠早期胚胎死亡的阻碍。为了产生有丝分裂检查点功能障碍的小鼠模型，我们产生了具有亚型BUBR 1等位基因（BUBR 1 hypo）的小鼠。尽管小鼠的BUBR 1蛋白水平显著降低，但对于亚型BUBR 1等位基因纯合子的小鼠是存活的。初步数据表明，在几个纯合突变小鼠中形成了组织学证实的肿瘤。对来自13.5天大纯合突变胚胎的早期传代成纤维细胞的详细分析表明，BUBR 1表达的减少导致过早的姐妹染色单体分离和非整倍体。在这个项目中，我们提出了实验来阐明BUBR 1的生物学作用，以及BUBR 1功能障碍可能导致恶性细胞转化的机制。在具体目标一中，我们将使用诱导型BUBR 1敲除细胞系来建立BUBR 1及其关键功能结构域的体内作用。在具体目标二中，我们将确定低形态BUBR 1小鼠中自发和致癌物诱导的肿瘤形成率，并在生物体水平上研究BUBR 1功能障碍对染色体不稳定性的影响。在具体目标三中，我们将确定能够与BUBR 1合作形成肿瘤的致瘤途径。这些研究将为了解BUBR 1的正常功能提供有价值的见解，并有助于阐明有丝分裂纺锤体组装检查点控制中的错误如何导致对肿瘤形成的易感性增加。