Repair Mechanisms For Oxidative DNA Damage

为了生存，好氧生物代谢氧气以产生能量。在这个过程中，细胞会产生活性化学物质，称为活性氧簇(ROS)。ROS可以攻击所有细胞成分，包括脂质、蛋白质和DNA。这种氧化损伤与衰老过程和人类疾病，即癌症和神经退化有关。我们一直对确定修复DNA氧化损伤的生化和细胞机制感兴趣。特别是，我们描绘了参与碱基切除修复(BER)途径的特定蛋白质的结构-功能机制和生物学贡献。这一过程包括识别和切除DNA损伤，以及恢复正常的遗传内容。DNA修复的缺陷会导致突变或细胞死亡，从而导致人类疾病的发展。我们的大部分工作都涉及确定APE1的生化功能，APE1是修复DNA中基本位点的主要人类蛋白质。我们和其他人已经证明，这种蛋白质主要有助于修复基本损伤，这是一种常见的遗传损伤。此外，我们还发现，APE1有助于DNA中3个？-修饰的修复，如错配、磷酸基团、磷酸凝胶和酪氨酸残基。这些发现扩展了已知的由这种酶处理的底物的谱系，并提示了APE1的其他生物学功能。我们最近还发现，环境金属铅是APE1活性的有效抑制剂。这些结果表明，这种共致突变的重金属可能通过抑制体内APE1的修复功能而诱导其致癌作用。目前正在进行研究以解决这一问题。此外，我们还开始了研究，以确定XRCC1的生化和细胞贡献，XRCC1是一种主要的单链断裂修复因子。这种蛋白质主要作为支架成分，协调有效DNA修复所需的特定蛋白质-蛋白质相互作用。我们最近报道了XRCC1与DNA复制之间的一个新的联系，因为XRCC1被发现直接与复制因子增殖细胞核抗原相互作用和共定位。继续进行的其他研究重点是：(I)描述人群中氨基酸变异对功能的影响及其在疾病易感性中的作用；(Ii)设计数学模型来评估与BER有关的生物学问题。未来的研究将继续为理解与人类健康相关的问题建立一个基本的结构-功能基础。

To live, aerobic organisms metabolize oxygen to generate energy. During this process, cells create reactive chemicals called reactive oxygen species (ROS). ROS can attack all cellular constituents, including lipids, proteins, and DNA. Such oxidative damage has been associated with the aging process and human disease, namely cancer and neurodegeneration. We have been interested in defining the biochemical and cellular mechanisms for repairing oxidative DNA damage. In particular, we have delineated the structure-function mechanisms and biological contributions of specific proteins that participate in the base excision repair (BER) pathway. This process involves the recognition and excision of DNA damage, and restoration of the normal genetic content. Defects in DNA repair can give rise to mutations or cell death, leading to the development of human disease. Much of our effort has involved defining the biochemical functions of Ape1, the major human protein that repairs abasic sites in DNA. This protein has been shown by us and others to contribute predominantly to the repair of abasic lesions, a frequent genetic damage. In addition, we have shown that Ape1 contributes to the repair of 3?-modifications in DNA, such as mismatches, phosphate groups, phosphogycolates, and tyrosyl residues. These findings expand the known repertoire of substrates processed by this enzyme, and suggest additional biological functions for Ape1. We have also recently discovered that the environmental metal, lead, is a potent inhibitor of Ape1 activity. These results suggest that this co-mutagenic heavy metal may elicit its carcinogenic effects by inhibiting the repair function of Ape1 in vivo. Studies are currently underway to address this issue. We have moreover initiated studies to determine the biochemical and cellular contributions of XRCC1, a major single-strand break repair factor. This protein functions primarily as a scaffolding component, orchestrating specific protein-protein interactions required for efficient DNA repair. We recently reported a novel link between XRCC1 and DNA replication, as XRCC1 was found to directly interact and co-localize with the replication factor PCNA. Other research emphases that continue are (i) delineating the functional impact of amino acid variation in the population and its role in disease susceptibility and (ii) devising mathematical models for assessing biological questions related to BER. Future studies will continue to build a basic, structure-function foundation for understanding matters associated with human health.