Base Excision Repair, Genetic Integrity & Health Span

描述（由申请人提供）：DNA损伤可引起多种细胞反应，包括1)DNA复制、转录和细胞周期进展的抑制，2)细胞死亡，以及3)突变。DNA损伤的这些生物学后果会扰乱正常的细胞功能，影响健康寿命。生物体已经进化出基因组保护机制，例如DNA修复途径，以尽量减少DNA损伤的有害影响。无论如何，在各种组织中，DNA损伤和突变随着年龄的增长而增加，从而危及健康。随着年龄的增长，遗传完整性的降低与某些组织中碱基切除修复活性的降低和DNA聚合酶- β活性/丰度的降低相对应。拟议研究的目的是确定DNA聚合酶β依赖的碱基切除修复（BER）对基因组完整性、健康寿命和寿命的贡献程度。由于缺乏校对活性，DNA聚合酶具有相对较低的保真度。在携带突变报告基因的转基因小鼠脑组织中，随着年龄的增长，突变频率不会增加，但小鼠确实表现出老年动物大脑中BER减少和DNA聚合酶β活性降低。相比之下，从年轻的成年DNA聚合酶- β杂合敲除小鼠获得的雄性生殖细胞显示出增加的自发突变频率。这些和其他数据表明，DNA聚合酶活性的变化可能在哺乳动物组织中介导不同的影响。要测试的总体假设是DNA聚合酶β丰度/活性的调节将在不同年龄的组织中产生不同的影响。小鼠模型和来源于小鼠模型的细胞系，DNA聚合酶- β表达/活性正常、增强或降低，将用于检查DNA聚合酶- β活性改变的潜在保护和有害作用。遗传完整性，细胞凋亡和病理学将使用各种分子，生物化学和细胞生物学方法进行检查。

DESCRIPTION (provided by applicant): DNA damage can elicit a variety of cellular responses including 1) inhibition of DNA replication, transcription and progression through the cell cycle, 2) cell death, and 3) mutagenesis. These biological consequences of DNA damage can perturb normal cellular function and impact health span. Organisms have evolved with genome safeguarding mechanisms, such as DNA repair pathways, to minimize the deleterious effects of DNA damage. Regardless, DNA damage and mutagenesis increase with age in a variety of tissues, thereby endangering health span. The decreased genetic integrity associated with older age corresponds to decreased base excision repair activity, and decreased DNA polymerase -beta activity/abundance in some tissues. The purpose of the proposed studies is to determine the extent to which DNA polymerase-beta dependent base excision repair (BER) contributes to genomic integrity, health span and lifespan. Lacking a proofreading activity, DNA polymerase-beta has a relatively low fidelity. Brain tissue in transgenic mice carrying a mutational reporter transgene do not display an increased mutant frequency with older ages, but mice do exhibit decreased BER and a reduced DNA polymerase-beta activity in brain of older animals. In contrast, male germ cells obtained from young adult DNA polymerase-beta heterozygous knockout mice display an increased spontaneous mutant frequency. These and other data suggest that changes in DNA polymerase-beta activity could mediate different effects among mammalian tissues. The overall hypothesis to be tested is that modulation of DNA polymerase beta abundance/activity will have differential effects among tissues relative to age. Mouse models, and cell lines derived from the mouse models, with normal, enhanced or reduced DNA polymerase-beta expression/activity will be used to examine the potentially protective and deleterious effects of altered DNA polymerase-beta activity. Genetic integrity, apoptosis, and pathology will be examined using a variety of molecular, biochemical and cell biological approaches.