Project 2

项目2

• 批准号: 6752167
• 负责人: DANIEL D LOEB
• 金额: $ 20.33万
• 依托单位: UNIVERSITY OF WISCONSIN-MADISON
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-05-29 至 2008-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6752167
• 关键词: DNA replication; Hepadnaviridae; RNA directed DNA polymerase; circular DNA; duck hepatitis B virus; gene mutation; genetic regulatory element; hepatitis B virus group; natural gene amplification; nucleic acid biosynthesis; oncogenic virus; tissue /cell culture; transcription factor; viral carcinogenesis; virus genetics; virus protein; virus replication

Hepatitis B virus (HBV) is the most prevalent human tumor virus. It is estimated that chronic HBV infection causes 1,000,000 cases of liver cancer annually. HBV must actively replicate within liver cells to maintain its chronic infection. We work to understand how HBV carries out the individual steps by which it replicates its genome in order to understand how this virus contributes to human cancer. To date, most insights into hepadnavirus DNA replication have come through the study of the avian hepadnavirus, duck hepatitis B virus (DHBV). Over the past decade, our laboratory has made multiple contributions to the understanding of hepadnavirus DNA replication by studying DHBV. During this last funding period our most significant progress was made in elucidating the mechanism of the templates switches during the synthesis of plus-strand DNA of DHBV. These analyses have elucidated two fundamental mechanisms that contribute to the template switching during avian hepadnavirus plus-strand synthesis: (1) a local DNA secondary structure that suppresses in situ priming, and therefore contributes to primer translocation; and (2) a long-distance DNA secondary structure that juxtaposes the donor and acceptor templates for primer translocation and circularization. We propose to develop a mechanistic understanding of HBV DNA replication that builds on and exceeds our current understanding of DHBV DNA replication. This project has three aims: (I) To characterize the process of minus-strand synthesis with an emphasis on the mechanism of the template switch after the synthesis of the fourth nucleotide of minus-strand DNA; (II)To characterize the mechanisms that are important for the crucial events during plus-strand DNA synthesis. These events include the specificity of primer generation and the initiation of plus-strand DNA synthesis, the regulation of in situ priming, and the mechanisms of the two plus-strand template exchanges, primer translocation and circularization; and (III)To determine the mechanisms by which cccDNA amplification is regulated.

乙型肝炎病毒（HBV）是最流行的人类肿瘤病毒。据估计，慢性乙型肝炎病毒感染每年导致 1,000,000 例肝癌。乙型肝炎病毒必须在肝细胞内积极复制才能维持其慢性感染。我们致力于了解乙型肝炎病毒如何执行复制其基因组的各个步骤，以便了解该病毒如何导致人类癌症。迄今为止，对嗜肝DNA病毒DNA复制的大部分了解都是通过对禽嗜肝DNA病毒、鸭乙型肝炎病毒(DHBV)的研究得出的。在过去的十年中，我们的实验室为理解 通过研究 DHBV 进行肝炎病毒 DNA 复制。在最后的资助期间，我们最重要的进展是阐明 DHBV 正链 DNA 合成过程中模板转换的机制。这些分析阐明了禽嗜肝DNA病毒正链合成过程中有助于模板转换的两个基本机制：（1）抑制原位引发的局部DNA二级结构，从而有助于引物易位； (2) 长距离 DNA 二级结构，将供体和受体模板并置以进行引物易位和环化。我们建议建立对 HBV DNA 复制的机制理解 并超出了我们目前对 DHBV DNA 复制的理解。该项目有三个目标：（一）表征负链合成过程，重点研究负链DNA第四个核苷酸合成后模板转换的机制； (II) 描述正链 DNA 合成过程中关键事件的重要机制。这些事件包括引物生成的特异性和正链DNA合成的启动、原位引发的调节以及两个正链模板交换、引物易位和环化的机制； (III)确定cccDNA扩增的调节机制。