DNA MODIFICATIONS--I COMPOUNDS AS BIOMARKERS OF AGING

我们将应用32 P标记技术来研究年龄- 依赖的DNA修饰，称为I-化合物，作为潜在的 衰老的生物标志物 化合物是最近发现的DNA 在我们的实验室中发现的类似加合物的DNA衍生物， 在啮齿动物组织中随年龄增长而增加。 I-化合物概况是 强烈依赖于组织，物种和（在较小程度上）性别 动物。 它们似乎没有表现出动物间的差异， 在相同年龄的动物中，无论是定性的还是定量的。 因此，I-化合物可以提供衰老的定量生物标志物 如果测量的话， 在容易接近的细胞或组织中。 我们将检验这一假设 使用NIA/NCTR生物标志物研究群体的大鼠， 白色血细胞和皮肤的DNA，即可从 最小程度的入侵人类。 将从个体中分离白色血细胞和皮肤DNA 雌性和雄性Fischer 344（F344）、Brown-Norway（BN）和F344 不同年龄的xBN杂交大鼠，来自自由进食和 限制饮食的群体。 将有8个年龄点：4，6，8，10， 12、16、20和24个月，每个时间点6只大鼠。 此外，肝脏 肾脏DNA将从合并的组织样本中分离出来， 在每个年龄点的生物标志物研究群体大鼠。 水平 和模式的I-化合物将被分析的32 P- 共价DNA修饰的标记后测定。 共 1536份DNA样本将在5年的时间里进行检查， 该项目 对大鼠肝、肾DNA进行分析， 显示I化合物是否在内脏器官中平行变化 那些在白色血细胞和皮肤。 在每个年龄段， 将进行一些分析，以评估这种方法， 其重现性、灵敏度、显著性、 变化、非致死性（例如，使用白色血细胞），潜在 与人类衰老的相关性和技术要求。 这 研究将提供一个明确的答案， I-化合物的测量是否会提供有用的 非侵入性的衰老生物监测方法。

We will apply a 32P-labeling technique to investigate age- dependent DNA modifications, termed I-compounds, as potential biomarkers of aging. I-compounds are recently discovered DNA adduct-like DNA derivatives that were found in our laboratory to increase with age in rodent tissues. I-compound profiles are strongly dependent on tissue, species, and (to a lesser extent) sex of animals. They appear to show little inter-animal variation, both qualitatively and quantitatively, in animals of the same age. I-compounds may thus provide a quantitative biomarker of aging that would be useful in the biomonitoring of humans if measured in easily accessible cells or tissues. We will test this hypothesis using rats of the NIA/NCTR biomarker research colony, focusing on DNA of white blood cells and skin, i.e. tissues available from humans with a minimum degree of invasiveness. White blood cell and skin DNA will be isolated from individual female and male Fischer 344 (F344), Brown-Norway (BN), and F344 x BN hybrid rats of different ages, from both ad libitum fed and dietary restricted groups. There will be 8 age points: 4, 6, 8, 10, 12, 16, 20, and 24 months and 6 rats per point. In addition, liver and kidney DNA will be isolated from pooled tissue samples of the biomarker research colony rats at each of the age points. Levels and patterns of I-compounds will be analyzed by a 32P- postlabeling assay for covalent DNA modifications. A total of 1536 DNA specimens will be examined over the 5-year course of the project. Analysis of liver and kidney DNA of the rats will show whether I-compound changes in internal organs parallel those in white blood cells and skin. At each age, a sufficient number of analyses will be conducted to assess this approach in terms of its reproducibility, sensitivity, significance of rate of change, non-lethality (e.g., use of white blood cells), potential relevance to human aging, and technical requirements. This research will provide a definitive answer to the question as to whether the measurement of I-compounds will provide a useful non-invasive method for biomonitoring of aging.