Mechanisms of human LINE-1 retrotransposition and DNA repair

人类 LINE-1 逆转录转座和 DNA 修复机制

• 批准号: 5408989
• 负责人: Professor Dr. Gerald G. Schumann
• 金额: --
• 依托单位: Paul-Ehrlich-Institut - Bundesinstitut für Impfstoffe und biomedizinische Arzneimittel
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2003
• 资助国家: 德国
• 起止时间: 2002-12-31 至 2008-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/5408989?language=en
• 关键词: Mechanisms; human; LINE; retrotransposition; DNA

LINE-1 elements (L1) represent about 17% of the human genome and play a major part in shaping the mammalian genome, not only through their own expansion but also through the mobilization of non-L1 sequences. Despite the clearly demonstrated impact this group of active, mobile elements has on structure, organization and stability of mammalian genomes and the diseases that are caused by their action, only few laboratories investigate the biology of L1 retrotransposition worldwide. We want to elucidate the mechanisms of human LINE-1 retrotransposition and identify the components that are involved in this genome shaping process. The process of L1 integration can be devided into "Target-Primed Reverse Transcription" (TPRT), which describes the initiating step of L1 replication, integration and minus-strand synthesis, and plus-strand synthesis that is not understood so far. Our first goal is to determine L1-encoded gene products and host factors that are involved in the insertion of a new L1 copy into the genome and shed light on the mechanism of L1 integration. We will attempt to reveal details about the mechanism of plus-strand synthesis of L1 retrotransposition by analysis of target site duplications from L1- and Alu insertions, preexisting in the genome of human cells. Since DNA damage caused by L1-specific endonuclease activity is repaired by the host as part of the L1 integration process, we want to identify those factors of the host´s repair mechanisms that take part in Double-Strand Break repair linked to L1 retrotransposition. If the host´s DNA repair mechanism is impaired, L1 activity is causing chromosomal damage. Furthermore, first indications exist for an upregulation of L1 expression in tumor cells. Therefore, it is our second goal to systematically characterize the expression of functional L1 elements in cancer cell lines and evaluate the effect of L1 retrotransposition on large-scale genome rearrangements underlying cancerogenic events.

LINE-1元件（L1）占人类基因组的约17%，并在塑造哺乳动物基因组中发挥重要作用，不仅通过其自身的扩展，而且通过非L1序列的动员。尽管这组活跃的移动的元件对哺乳动物基因组的结构、组织和稳定性以及由其作用引起的疾病具有明确的影响，但全世界只有少数实验室研究L1反转录转座的生物学。我们希望阐明人类LINE-1逆转录转座的机制，并确定参与这一基因组成形过程的组件。L1整合的过程可分为靶向逆转录（TPRT）和正链合成，靶向逆转录描述了L1复制、整合和负链合成的起始步骤，而正链合成目前尚不清楚。我们的第一个目标是确定L1编码的基因产物和宿主因子，这些因子参与将新的L1拷贝插入基因组中，并阐明L1整合的机制。我们将试图通过分析人类细胞基因组中预先存在的L1和Alu插入的靶位点重复来揭示L1逆转录转座的正链合成机制的细节。由于L1特异性核酸内切酶活性引起的DNA损伤作为L1整合过程的一部分由宿主修复，因此我们希望确定参与与L1逆转录转座相关的双链断裂修复的宿主修复机制的那些因素。如果宿主的DNA修复机制受损，L1活性会导致染色体损伤。此外，存在肿瘤细胞中L1表达上调的第一个迹象。因此，这是我们的第二个目标，系统地表征功能L1元素在癌细胞系中的表达，并评估L1逆转录转座对大规模基因组重排的致癌事件的影响。