OVEREXPRESSION OF GENES OF POTENTIAL RELEVANCE TO DNA DAMAGE OF AGING

项目1（原项目6）将继续评估两个“候选人” 以及有可能保护衰老DNA的“匿名”基因 哺乳动物细胞免受氧化损伤和诱变。根据 根据衰老的氧化损伤理论，这些基因被预测会增强 寿命和延缓与年龄有关的疾病，特别是晚年 肿瘤。已评估的候选cDNA构建体的子集 已经被用来合成转基因小鼠 通过一种特别强的，组成性的， 启动子/增强子（鸡β肌动蛋白/CMV增强子）。重复两行 这样的转基因（和具有可比遗传特性的对照系） 背景）（C57 BL/6 NNia x DBA/2NNia F1）将扩展为老化队列 并表征转基因的表达和 DNA损伤;后者的方法将从细胞遗传学和 微核试验，以确定频率和频谱， APRT基因座突变。正在评估的转基因包括 对于人过氧化氢酶、人超氧化物歧化酶-1和-2、小鼠γ- 谷氨酰半胱氨酸合成酶和酵母脱嘌呤核酸内切酶。特别 将关注靶向细胞核的过氧化氢酶构建体; 这些将与先前描述的SOD-1转基因物交配。 一个 初步的一系列实验也将进行长期目标 分离出匿名的鸟类基因组序列， 我们最近的观察表明， 抗氧化应激。

Project 1 (formerly Project 6) will continue to evaluate both "candidate" and "anonymous" genes that have the potential to protect the DNA of aging mammalian cells from oxidative damage and mutagenesis. According to oxidative damage theories of aging, such genes are predicted to enhance life span and to retard age-related disorder's, particularly late-life neoplasms. A subset of candidate cDNA constructs that have been evaluated in cell culture have been used to synthesize transgenic mice overexpressing these cDNAs via an exceptionally strong, constitutive promoter/enhancer (chick beta actin/CMV enhancer). Duplicate lines of two such transgenics (and of a control line with comparable genetic background) (C57BL/6NNia x DBA/2NNia F1) will be expanded as aging cohorts and characterized as to expression of the transgene and the level of damage to DNA; methods for the latter will range from cytogenetic and micronucleation assays to determinations of frequencies and spectrum of mutation at the APRT locus. Among the transgenes being evaluated are those for human catalase, human superoxide dismutase-1 and -2, mouse gamma- glutamyl cysteine synthetase and yeast apurinic endonuclease. Special attention will be given to catalase constructs targeted to the nucleus; these will be mated with previously described SOD-1 transgenics . An initial set of experiments will also be undertaken with the long term goal of isolating anonymous avian genomic sequences that are responsible for our recent observations indicating that avian somatic cells are unusually resistant to oxidative stress.