DNA damage and repair in old and young and in participants in the BLSA

双链断裂是DNA中非常危险的损伤，必须修复才能使细胞完成复制和转录。双链断裂修复缺陷的细胞易受基因组不稳定性的影响，这些缺陷的个体患癌症的风险通常较高。双链断裂的存在可以通过检测细胞中被称为H2AX的组蛋白变体的磷酸化形式来确定。蛋白质的磷酸化在双链断裂附近迅速发生，并持续到断裂被修复。因此，phospho-H2AX作为断裂的替代标记物。该物种可以很容易地通过免疫荧光技术检测到，因此可以在单细胞中检测到。我们通过测定来自BLSA项目中供者的血源性细胞中phospho-H2AX的水平，来验证老年个体的细胞中双链断裂水平高于年轻人的假设。结果表明，老年个体的细胞比年轻个体的细胞含有更多的H2Ax位点。我们还通过凝胶电泳测定单细胞水平的DNA修复。

Double strand breaks are very dangerous lesions in DNA and must be repaired to allow cells to complete replication and transcription. Cells with deficiencies in double strand break repair are subject to genomic instability and individuals with these deficiencies are often at elevated risk of cancer. The presence of double strand breaks can be determined by examining cells for the phosphorylated form of a histone protein variant known as H2AX. Phosphorylation of the protein occurs rapidly in the vicinity of a double strand break, and persists until the break is repaired. Consequently phospho-H2AX serves a surrogate marker for breaks. This species can be easily detected by immunofluorescence techniques, and thus can be detected in single cells. We are testing the hypothesis that double strand breaks are presented in elevated levels in cells from aged individuals, as compared with younger individuals, by determining the level of phospho-H2AX in blood derived cells from donors in the BLSA program. The results indicate that cells from older individuals contain more frequent H2Ax sites than cells fromyounger individuals. The frequency We are also measuring DNA repair at the single cell level by gel electrophoresis assays.