Functions of the BLM Helicase in Telomere Maintenance

BLM 解旋酶在端粒维护中的功能

基本信息

批准号：
7617657
负责人：
Joanna Louise Groden
金额：
$ 31.13万
依托单位：
OHIO STATE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-05-01 至 2010-02-28
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7617657
关键词：
Affect Age BLM gene Binding Proteins Bloom Syndrome Bloom syndrome protein Cancer Cell Growth Cell Cycle Cells Chromosome Breakage Chromosomes Complex DNA DNA Damage DNA Double Strand Break Data Double Strand Break Repair Gene Proteins Genes Genetic Recombination Genetically Engineered Mouse Genome Stability Genomics Goals Heat-Shock Proteins 90 Hereditary Disease Homologous Gene Human Human Genome Immunohistochemistry Immunologic Deficiency Syndromes Immunoprecipitation In Vitro Individual Inherited Laboratories Learning Maintenance Male Infertility Malignant Neoplasms Mammalian Cell Mediating Mitosis Modification Mutate Nonhomologous DNA End Joining Normal Cell Nucleic Acids Phospho-Specific Antibodies Phosphorylation Site Photosensitivity Post-Translational Protein Processing Predisposition Process Proteins Regulation Role Site Syndrome TEP1 gene TERF1 gene Telomerase Telomere Maintenance Telomeric Repeat Binding Protein 1 Testing Therapeutic Topoisomerase Work Yeasts abstracting helicase homologous recombination immortalized cell in vitro Assay in vitro activity in vivo mutant neoplastic novel oncology positional cloning protein complex protein expression repaired telomere

项目摘要

DESCRIPTION (provided by applicant): Human BLM encodes a recQ-like DNA helicase that is important for the maintenance of genomic stability. When both copies of this gene are mutated, the resulting hereditary disease, known as Bloom's syndrome (BS), is characterized by sun-sensitivity, small stature, immunodeficiency, male infertility, and a tremendous predisposition to cancer of all sites and types. Cells from BS individuals are characterized by chromosome breakage and other chromosomal anomalies that are indicative of increased somatic recombination. Notably, telomeric associations (TAs) between homologous chromosomes are also present in non- immortalized and immortalized cells from BS individuals. Following the positional cloning of the BLM gene, our laboratory has investigated the functions of the BLM helicase in DNA double strand break repair processes such as non-homologous end joining, homologous recombination-mediated repair, and synthesis-dependent strand annealing. Our work has also suggested a role for BLM in recombination- mediated mechanisms of telomere elongation or ALT (alternative lengthening of telomeres), processes that maintain/elongate telomeres in the absence of telomerase. BLM preferentially associates with the telomere- specific binding proteins TRF1 and TRF2 in cells using ALT; its helicase activity can be modulated by these interactions. Our preliminary data identify and validate other proteins that uniquely interact with BLM and TRF2 in cells using ALT, demonstrate that these protein interactions modify enzymatic activity of BLM and its partner topoisomerase IIalpha, and show that modification of five putative phosphorylation sites can alter unwinding of DNA substrates. We hypothesize that BLM complex formation and modification occur dynamically during the specific nucleic acid transactions that are required to protect the telomere, to align chromosome sequences at homologous telomeres, to permit strand invasion and elongation, and/or ultimately to disentangle telomeres. These ideas will be investigated by analyses of BLM modification, localization and protein partnering during telomere elongation, and by modifying these interactions or modifications in vitro and in vivo using genetically engineered mice. The immediate goal of this application is to determine the mechanism by which BLM functions to maintain telomeres. This work has important implications for learning how cells maintain their genomic integrity, how they age or become immortal, and ultimately for developing better therapeutic strategies in oncology. PUBLIC HEALTH RELEVANCE: Inherited syndromes that predispose to cancer have provided us an opportunity to study the genes and proteins that are important for keeping normal cells from becoming neoplastic. The BLM helicase is one of these proteins, as it seems to be required to maintain stability of the human genome. Its role in the maintenance of chromosome ends is especially important, as it is these mechanisms that enable cells to gain the ability to grow indefinitely. The study of BLM therefore represents an opportunity for us to learn how we can control the growth of cancer cells in a therapeutic setting.

描述（由申请人提供）：人类BLM编码一种RECQ样DNA解旋酶，这对于维持基因组稳定性很重要。当该基因的两个副本被突变时，所得的遗传性疾病（称为Bloom's综合征（BS））的特征是太阳敏感性，小身材，免疫缺陷，男性不育症和对所有部位和类型癌症的巨大倾向。来自BS个体的细胞的特征是染色体断裂和其他染色体异常，这些异常表明体细胞重组增加。值得注意的是，来自BS个体的非永生和永生细胞中同源染色体之间的端粒关联（TA）也存在。在BLM基因的位置克隆之后，我们的实验室研究了BLM解旋酶在DNA双链断裂修复过程中的功能，例如非同源末端连接，同源重组介导的修复以及依赖于合成的链链链式退火。我们的工作还提出了BLM在端粒伸长或ALT的重组介导的机制中的作用（端粒的替代延长），即在没有端粒酶的情况下维持/伸长端粒的过程。 BLM优先使用ALT与细胞中的端粒结合蛋白TRF1和TRF2相关联；它的解旋酶活性可以通过这些相互作用来调节。我们的初步数据识别并验证了使用ALT与BLM和TRF2相互作用的其他蛋白质，证明这些蛋白质相互作用改变了BLM及其伴侣拓扑异构酶iialpha的酶促活性，并表明修改了五个假定的磷酸化位点可以改变DNA抑制剂的dna suptrates。我们假设BLM复合物的形成和修饰是在特定的核酸交易中动态发生的，这些核酸交易是保护端粒所需的特定核酸交易，以使同源端粒处的染色体序列对齐，以允许链入侵和伸长和/或最终脱离端粒。这些想法将通过在端粒伸长率期间的BLM修饰，定位和蛋白质伴侣的分析，以及使用基因工程小鼠的体外和体内修改这些相互作用或体内修饰。该应用程序的直接目标是确定BLM功能维护端粒的机制。这项工作对学习细胞如何保持其基因组完整性，它们的年龄或不朽以及最终在肿瘤学中发展更好的治疗策略具有重要意义。公共卫生相关性：易感癌症的遗传综合征为我们提供了研究基因和蛋白质的机会，这些基因和蛋白质对于防止正常细胞成为肿瘤很重要。 BLM解旋酶是这些蛋白质之一，因为似乎需要维持人类基因组的稳定性。它在维持染色体末端的作用尤其重要，因为这些机制使细胞能够无限期地增长能力。因此，对BLM的研究为我们提供了一个机会，可以学习如何在治疗环境中控制癌细胞的生长。