OVEREXPRESSION OF GENES OF POTENTIAL RELEVANCE TO DNA DAMAGE OF AGING

项目1(前身为项目6)将继续评估这两个“候选人” 和“匿名”基因，这些基因有可能保护衰老的DNA 哺乳动物细胞免受氧化损伤和诱变。根据 衰老的氧化损伤理论，这样的基因被预测会增强 延长寿命，延缓老年性疾病，特别是晚年 肿瘤。已评估的候选cdna构建的子集 在细胞培养中已被用于合成转基因小鼠 通过一种异常强大的、结构性的 启动子/增强子(鸡β肌动蛋白/巨细胞病毒增强子)。重复行，每行两行 这种转基因(以及具有可比基因的控制系) 背景)(C57BL/6Nia x DBA/2Nia F1)将扩大为老龄队列 并以转基因的表达和表达水平为特征 对DNA的损伤；后者的方法包括细胞遗传学和 微核技术用于血吸虫病的频率和光谱测定 Aprt基因座的突变。在正在评估的转基因中有 对于人过氧化氢酶，人超氧化物歧化酶-1和-2，小鼠伽马- 谷氨酰半胱氨酸合成酶和酵母无嘌呤核酸内切酶。特价 将关注针对细胞核的过氧化氢酶结构； 这些基因将与之前描述的SOD-1转基因基因交配。一个 还将进行一系列初步实验，以实现长期目标 分离匿名的禽类基因组序列 我们最近的观察表明，鸟类体细胞是不寻常的 能抵抗氧化应激。

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.