Studies of Chemically Labile Alkylation Damage in DNA

DNA 中化学不稳定烷基化损伤的研究

基本信息

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
项目类别：
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

项目摘要

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.

抽象的烷化剂引起的烷基化 DNA 损伤促进突变和癌症发展。是多种烷基化诱变剂、致癌剂和抗癌剂的靶标，产生阳离子 N7-烷基鸟嘌呤（N7-烷基G）加合物是主要损伤，这些损伤的半衰期为数小时至数天。因此，带正电荷的 N7-烷基G 损伤也可以影响 DNA 复制和转录。进行进一步修饰以产生继发性损伤，例如烷基-甲酰胺嘧啶（烷基-FapyG）许多诱变剂/致癌物诱导的 N7- 的识别、修复和诱变机制。烷基G和黄曲霉毒素B1-FapyG病变，除N7-黄曲霉毒素B1-G和黄曲霉毒素B1-FapyG等少数病变外加合物的特征仍然很差，因此无法完全理解它们的贡献突变和癌症发展的主要损害例如，主要的诱变特性。由致癌的氧化苯乙烯产生的 N7-烷基G 加合物尚不清楚。部分原因是制备含有位点特异性 N7-烷基G-和烷基-FapyG 的技术困难 DNA，这归因于 N7-烷基G 核苷的快速纯化和烷基-G 核苷的容易异构化 FapyG 在固相 DNA 合成过程中为了克服 N7-烷基G 核苷的稳定性问题，我们有开发了一种 2’-氟技术，通过提高 N7- 的稳定性来防止自发纯化为了解决烷基-FapyG的异构化问题，我们采取了后合成的方法。我们的初步研究是从含有 N7-烷基 G 的 DNA 中产生含有烷基 FapyG 的 DNA 的方法。表明鸟嘌呤 N7 烷基化可以通过促进稀有碱基的形成来影响碱基配对特性烯醇互变异构体、顺式碱基构象和/或嵌入我们的中心假设是N7-烷基G和烷基-。 FapyG 加合物通过改变碱基配对特性来促进突变和癌症发展我们的长期研究目标是阐明化学不稳定的生物影响。使用创新方法（例如 2'-F 化学、 polβ宿主-客体-复合体系统和合成后DNA修饰的目的是解剖生物。 N7-烷基G和烷基-FapyG通过强效烷基化诱变剂和抗癌剂诱导病变的后果尼古丁特异性亚硝胺、氧化苯乙烯、氮芥和 N-甲基苄基亚硝胺等药剂。为了实现这一目标，我们将表征碱基配对特性以及识别、诱变、使用合成、生物化学、结构生物学和细胞方法的成功执行将极大地促进所提出的计划。增进我们对致癌物/药物诱导的 N7-烷基G 和烷基-FapyG 病变对碱基对构象、稳定性、互变异构、诱变、识别和修复，从而提供重要的深入了解烷基化损伤诱导的突变和癌症发展。