Base Excision Repair, Genetic Integrity & Health Span

描述（由申请人提供）：DNA损伤可引发多种细胞反应，包括1）抑制DNA复制、转录和细胞周期进展，2）细胞死亡，和3）诱变。DNA损伤的这些生物学后果可以扰乱正常的细胞功能并影响健康寿命。生物体已经进化出基因组保护机制，如DNA修复途径，以最大限度地减少DNA损伤的有害影响。无论如何，DNA损伤和诱变在各种组织中随着年龄的增长而增加，从而危及健康寿命。与老年相关的遗传完整性降低对应于碱基切除修复活性降低，以及某些组织中DNA聚合酶-β活性/丰度降低。拟议研究的目的是确定DNA聚合酶-β依赖性碱基切除修复（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-β具有相对较低的保真度。携带突变报告基因转基因的转基因小鼠的脑组织没有显示出随着年龄的增长而增加的突变频率，但小鼠确实表现出老年动物脑中BER降低和DNA聚合酶β活性降低。相比之下，从年轻成年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β活性的变化可能介导哺乳动物组织中的不同影响。待检验的总体假设是，DNA聚合酶β丰度/活性的调节将在组织中相对于年龄具有不同的影响。具有正常、增强或降低的DNA聚合酶-β表达/活性的小鼠模型和源自小鼠模型的细胞系将用于检查改变的DNA聚合酶-β活性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多种分子、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.