Studies of Chemically Labile Alkylation Damage in DNA

DNA 中化学不稳定烷基化损伤的研究

• 批准号: 10735154
• 负责人: Seongmin Lee
• 金额: $ 19.37万
• 依托单位: UNIVERSITY OF TEXAS AT AUSTIN
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-12 至 2028-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10735154
• 关键词: Affect; Aflatoxin B1; Alkylating Agents; Alkylation; Antineoplastic Agents; Base Excision Repairs; Base Pairing; Biochemical; Biological; Biological Assay; Bypass; Candidate Disease Gene; Carcinogens; Catalysis; Cells; Charge; Chemicals; Chemistry; Complex; DNA; DNA Alkylation; DNA Damage; DNA Maintenance; DNA Modification Process; DNA Structure; DNA biosynthesis; DNA glycosylase; DNA-Directed DNA Polymerase; Depurination; Development; Dissociation; Equilibrium; Etiology; Excision; Fluorine; Frequencies; Genes; Genetic Transcription; Goals; Guanine; Heterogeneity; Hour; Human; Imidazole; In Vitro; Individual; Induced Mutation; Isomerism; Ketones; Kinetics; Knowledge; Lesion; Light; Malignant Neoplasms; Mechlorethamine; Mediating; Modification; Molecular Conformation; Mutagenesis; Mutagens; Mutation; Nicotine; Nitrosamines; Nucleosides; Nucleotides; Pharmaceutical Preparations; Phase; Plasmids; Polymerase; Process; Property; Public Health; Publishing; Relaxation; Reporter; Reporting; Research; Role; Secondary Lesion; Site; Solid; Structure; System; Technology; Testing; Tobacco; adduct; anomer; antitumor agent; base; carcinogenesis; endonuclease; enol; genotoxicity; in vivo; innovation; insight; intercalation; ionization; knock-down; melting; mutation assay; nucleotide metabolism; prevent; programs; repair model; repaired; structural biology; styrene oxide; success; synthetic construct; tautomer; tool

ABSTRACT Alkylation DNA damage caused by alkylating agents promotes mutations and cancer development. Guanine N7 is targeted by a wide range of alkylating mutagens, carcinogens, and anticancer agents, producing the cationic N7-alkylguanine (N7-alkylG) adducts as major lesions. These lesions have half-lives of several hours to days in DNA and thus can affect DNA replication and transcription. The positively charged N7-alkylG lesions can also undergo further modification to generate secondary lesions such as alkyl-formamidopyrimidine (alkyl-FapyG) adducts. The recognition, repair, and mutagenesis mechanisms of many mutagen/carcinogen-induced N7- alkylG and alkyl-FapyG lesions, except for a few lesions such as N7-aflatoxin B1-G and aflatoxin B1-FapyG adducts, remain poorly characterized, thereby precluding a complete understanding of the contribution of these major lesions to mutations and cancer development. For example, the mutagenic properties of the predominant N7-alkylG adducts produced by the cancer-promoting styrene oxide are unknown. This knowledge gap has been due in part to the technical difficulty in preparing a site-specific N7-alkylG- and alkyl-FapyG-containing DNA, which is ascribed to the rapid depurination of N7-alkylG nucleosides and the facile isomerization of alkyl- FapyG during solid-phase DNA synthesis. To overcome the stability issue of N7-alkylG nucleosides, we have developed a 2’-fluorine technology that prevents spontaneous depurination by increasing the stability of N7- alkylG nucleosides. To solve the isomerization problem of alkyl-FapyG, we have taken a post-synthetic approach that produces alkyl-FapyG-containing DNA from N7-alkylG-containing DNA. Our preliminary studies show that guanine N7 alkylation can influence base-pairing properties by facilitating the formation of the rare enol tautomer, syn base conformation, and/or intercalation. Our central hypothesis is that N7-alkylG and alkyl- FapyG adducts promote mutations and cancer development by altering the base-pairing properties of the damaged guanine. Our long-term research goal is to elucidate the biological impacts of chemically labile alkylation damages and their secondary lesions using innovative approaches such as the 2’-F chemistry, the polβ host-guest-complex system, and post-synthetic DNA modification. The objective is to dissect the biological consequences of N7-alkylG and alkyl-FapyG lesions induced by potent alkylating mutagens and anticancer agents such as nicotine-specific nitrosamine, styrene oxide, nitrogen mustards, and N-methylbenzyl nitrosamine. To accomplish this objective, we will characterize the base-pairing properties and the recognition, mutagenesis, and repair mechanisms of N7-alkylG and alkyl-FapyG adducts using combined tools of synthetic, biochemical, structural biology, and cellular approaches. The successful execution of the proposed programs will greatly advance our knowledge of the impact of carcinogen/drug-induced N7-alkylG and alkyl-FapyG lesions on the base pair conformation, stability, tautomerism, mutagenesis, recognition, and repair, thereby providing important insights into the alkylation damage-induced mutations and cancer development.

抽象的 由烷基化剂引起的烷基化DNA损伤促进突变和癌症的发展。 Guanine N7 由多种烷基化诱变剂，致癌物和抗癌剂的靶向，产生阳离子 N7-烷基鸟嘌呤（N7-烷基）加合物作为主要病变。这些病变有几个小时到几天的半衰期 DNA，因此会影响DNA的复制和转录。带正电的N7-烷基病变也可以 进行进一步的修饰，以产生二级病变，例如烷基形成酰胺酰亚胺（烷基 - 抗血症） 加合物。许多诱变的N7-的识别，修复和诱变机制 烷基基和烷基 - 酸性病变，除了一些病变，例如N7-Aflatoxin B1-G和黄曲霉毒素B1-FAPYG 加合物的特征性不佳，从而完全理解这些贡献 突变和癌症发展的主要病变。例如，主要的诱变特性 由癌症苯乙烯氧化苯乙烯产生的N7-烷基加合物尚不清楚。这个知识差距有 我们应部分归因于准备特定地点的N7-烷基和烷基 - 抗毒素的技术困难 DNA被分配给N7-烷基核苷的快速部署和烷基的易于异构化 固相DNA合成过程中的FAPAPY。为了克服N7-烷基核酶的稳定问题，我们已经有 开发了一种2'-氟化技术，该技术通过提高N7-的稳定性来防止赞助部署 烷基核酶。为了解决烷基 - 酸性的异构化问题，我们采取了合成后 产生来自含N7-烷基DNA的含烷基饮食的DNA的方法。我们的初步研究 证明鸟嘌呤N7烷基化可以通过促进罕见的形成来影响碱基配对特性 烯醇互变异物，SYN碱基构象和/或插入。我们的中心假设是N7-烷基和烷基 Fapyg加合物通过改变 受损的鸟嘌呤。我们的长期研究目标是阐明化学不稳定的生物学影响 烷基化损伤及其二级病变，使用2'-F化学等创新方法 POLβ宿主 - 周期复合系统和合成后DNA修饰。目的是剖析生物学 由潜在烷基化诱变剂和抗癌引起的N7-烷基和烷基 - 脂肪治疗的后果 诸如尼古丁特异性亚硝基胺，苯乙烯，氮芥末和N-甲基苯甲酰硝基胺之类的药物。 为了实现这一目标，我们将表征碱基对的特性和识别，诱变， N7-烷基G和烷基 - 抗血症加合物的修复机制，使用合成，生化的组合工具 结构生物学和细胞方法。拟议程序的成功执行将大大 促进我们对致癌/药物诱导的N7-烷基和烷基 - 促疾病病变的影响的了解 碱基对构象，稳定性，互变异，诱变，识别和维修，从而提供重要 对烷基化损伤引起的突变和癌症发展的见解。