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Stem cell mutagenesis mediated by age and niche

年龄和生态位介导的干细胞突变

基本信息

批准号：
8275321
负责人：
Vivienne Ilona Rebel
金额：
$ 2.09万
依托单位：
UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-05-01 至 2012-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8275321
关键词：
Affect Age Aging Americas Animals Apoptosis B-Lymphocytes Bacteriophages Bone Marrow CREB-binding protein Cell Lineage Cell Separation Cell physiology Cells DNA DNA Damage DNA Repair DNA purification Data Defense Mechanisms Detection Development Disease Dysmyelopoietic Syndromes Elderly Engineering Event Failure Frequencies Future Gene Mutation Genetically Engineered Mouse Genome Genomics Goals Health Hematopoietic Hematopoietic stem cells Human In Vitro Incidence Intestines Knowledge Lead Link Lymphoid Malignant - descriptor Malignant Neoplasms Measures Mediating Mediator of activation protein Mus Mutagenesis Mutation Myelogenous Myeloid Cells Myelopoiesis Myeloproliferative disease Population Pregnancy Preventive Process Reading Relative (related person)Reporter Genes Research Risk Role Skin Stem cells Techniques Testing Time Tissues Transgenes Transgenic Mice Transplantation United States Wild Type Mouse age group cancer risk hematopoietic stem cell fate hematopoietic tissue human CREBBP protein in vivo middle age mouse CREB binding protein mouse model mutant normal aging novel progenitor regenerative research study self-renewal stem tumor tumorigenesis young adult

项目摘要

DESCRIPTION (provided by applicant): The incidence of cancer increases with age, suggesting that multiple events (DNA mutations) must take place for malignant transformation to occur. It is known that natural defense mechanisms serve to protect against accumulation of DNA mutations and to diminish the risk of developing cancer. Defense mechanisms are of particular importance in tissues with high cellular turnover, such as the skin, intestines, and the hematopoietic tissue, because each round of replication provides enormous opportunity to generate mutations. Currently, our understanding of how the genomic integrity in the different tissues is maintained during aging is limited largely to analyses of DNA damage, DNA repair, and mutagenesis in differentiated cells and tissues. There is increasing evidence pointing to the stem cells as important regulators of genome integrity for the tissues they reside in. We therefore hypothesize that it is a failure in stem cell function that links the increasing cancer incidence with aging. We will test this premise by measuring mutant frequency in hematopoietic stem cells and compare this to that measured in differentiated cells of the myeloid - and B-cell lineage. By obtaining purified cell populations from mice of 4 age groups, day 14.5 of gestation, young adult (8-10 weeks), middle-aged (15 months), and old (26- to 28 months), we will furthermore determine whether the mutant frequency within a particular cell population changes with age. As a read-out for mutagenesis we will use the spontaneous mutant frequency. Mice transgenic for a mutation reporter gene, LacI, will be used as bone marrow donors for the isolation of purified stem cells and differentiated populations. The transgene in the cells of these mice can be isolated and the presence of spontaneous mutants determined. It is well established that hematopoietic stem cell function is greatly affected by the microenvironment they reside in. To test whether the hematopoietic stem cell microenvironment also affects the genomic integrity of HSCs, we will furthermore follow the spontaneous mutation frequency in hematopoietic stem cells (isolated from LacI transgenic mice) that are subjected to 4 rounds of serial transplantation in wild- type mice versus mice heterozygous for the CREB binding protein (CBP). The latter was chosen because CBP mice show microenvironment-mediated loss of hematopoietic stem cell support and excess myeloid differentiation. With these experiments we will initiate a line of research that will eventually lead to a systematic analysis of cell intrinsic and extrinsic mediators of DNA damage and mutagenesis as a function of aging in HSCs. This is of importance because it may lead to the development of novel cancer-preventive measures. PUBLIC HEALTH RELEVANCE: The relative number of people above 65 years in the United States of America is steadily increasing, and thus cancer is a serious health issue. With this proposal we will obtain knowledge that will significantly contribute to our currently limited understanding of the positive correlation between cancer risk and age, possibly leading in the future to the development of more cancer-preventive measures.

描述(由申请人提供)：癌症的发病率随着年龄的增长而增加，这表明必须发生多个事件(DNA突变)才能发生恶性转化。众所周知，自然防御机制有助于防止DNA突变的积累，并降低患癌症的风险。防御机制在细胞周转率高的组织中尤其重要，如皮肤、肠道和造血组织，因为每一轮复制都提供了产生突变的巨大机会。目前，我们对不同组织在衰老过程中如何保持基因组完整性的理解主要局限于对分化细胞和组织中DNA损伤、DNA修复和突变的分析。越来越多的证据表明，干细胞是它们所在组织基因组完整性的重要调节器。因此，我们假设，是干细胞功能的失败将癌症发病率的增加与衰老联系在一起。我们将通过测量造血干细胞的突变频率来测试这一前提，并将其与髓系和B细胞谱系的分化细胞中的突变频率进行比较。通过从怀孕14.5天、青年(8-10周)、中年(15个月)和老年(26-28个月)的4个年龄组的小鼠获得纯化的细胞群，我们将进一步确定特定细胞群内的突变频率是否随年龄而变化。作为突变的读数，我们将使用自发突变频率。转基因突变报告基因laci的小鼠将被用作骨髓捐赠者，用于分离纯化的干细胞和分化的群体。可以分离出这些小鼠细胞中的转基因，并确定是否存在自发突变。众所周知，造血干细胞的功能很大程度上受其所处的微环境的影响。为了测试造血干细胞微环境是否也影响造血干细胞的基因组完整性，我们将进一步跟踪从LacI转基因小鼠分离的造血干细胞在野生型小鼠和CREB结合蛋白(CBP)杂合子小鼠中进行4轮连续移植后的自发突变频率。选择后者是因为CBP小鼠表现出微环境介导的造血干细胞支持丧失和过度髓系分化。通过这些实验，我们将启动一系列研究，最终将导致对HSCs中DNA损伤和突变的细胞内在和外在中介作为衰老的功能进行系统分析。这一点很重要，因为它可能导致新的癌症预防措施的发展。公共卫生相关性：美国65岁以上人口的相对数量正在稳步增加，因此癌症是一个严重的健康问题。通过这项建议，我们将获得一些知识，这些知识将大大有助于我们目前对癌症风险与年龄之间的正相关关系的有限理解，并可能在未来导致更多癌症预防措施的发展。