Mechanisms of subtelomere recombination in telomerase deficient tumors

端粒酶缺陷肿瘤中亚端粒重组的机制

• 批准号: 8030254
• 负责人: TAMMY A MORRISH
• 金额: $ 13.48万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-15 至 2013-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8030254
• 关键词: Accounting; B-Cell Lymphomas; Biological Assay; Biology; Brain Neoplasms; Cell Culture Techniques; Cells; Characteristics; DNA; DNA Repair; DNA biosynthesis; Drosophila genus; Enzymes; Event; Genes; Genetic Recombination; Glioblastoma; Goals; Growth; Human; Human Genome; Length; Loss of Heterozygosity; Mammalian Cell; Mesenchymal; Mobile Genetic Elements; Monitor; Mus; Neurons; Phase; Primary Neoplasm; RNA; Retrotransposition; Retrotransposon; Reverse Transcription; Role; Telomerase; Telomerase RNA Component; Telomerase inhibition; Telomere Maintenance; Testing; Yeasts; gene function; mouse genome; neoplastic cell; novel; repaired; sarcoma; small hairpin RNA; telomere; tumor; tumor growth; tumorigenesis

DESCRIPTION (provided by applicant): Telomere maintenance in the absence of telomerase can occur by various mechanisms, collectively termed ALT, for alternative lengthening mechanisms. Nearly 10% of human tumors, often sarcomas or glioblastomas, lack the enzyme telomerase for telomere maintenance. In order to study these non- telomerase telomere maintenance mechanisms we are using E5myc+mTR-/- mice, genetically deleted for the RNA component of telomerase (mTR), and crossed to E5myc+ mice, which develop B-cell lymphoma. To test the role of recombination in these non-telomerase telomere maintenance mechanisms we are currently using an shRNA approach to inhibit various recombination genes, and then examining the change in growth rate of tumors. To understand more about the mechanisms we then assay the tumors for subtelomere recombination. In this proposal we intend to examine the contribution of genes involved in replication fork stalling, and the role of DNA repair by a novel mechanism known as break-induced replication. To monitor break-induced replication in mammalian cells, we will develop assays to detect the hallmarks of break-induced replication. These characteristics include loss of heterozygosity, non-reciprocal translocations, and segmental duplications. Finally during the independent phase we intend to examine the role of LINE-1 retrotransposition during break-induced replication and telomere maintenance. Non- LTR retrotransposons, referred to as LINE-1 or L1, account for a significant fraction of the mouse and human genomes. These mobile genetic elements move by an RNA intermediate using a mechanism called target-primed reverse transcription. In addition we found that retrotransposition can also occur at endogenous DNA breaks and dysfunctional telomeres. Furthermore, non-LTR retrotransposons in Drosophila entirely contribute to the mechanism of telomere maintenance. Thus we intend to examine whether non-LTR retrotransposons also contribute to telomere maintenance in both human and mouse cells and thus account for the occurrence of tumors lacking telomerase. PUBLIC HEALTH RELEVANCE: Telomere maintenance can occur without telomerase and 10% of human tumors lack telomerase activity. These additional mechanisms can also contribute to telomere maintenance in tumors expressing telomerase and likely are selected in tumors inhibited for telomerase. These studies are relevant to understanding tumorigenesis that occurs in the absence of telomerase, including human sarcomas and potentially certain types of brain tumors. )

描述（由申请人提供）：在没有端粒酶的情况下，端粒的维持可以通过各种机制发生，统称为ALT，用于替代延长机制。近10%的人类肿瘤，通常是肉瘤或胶质母细胞瘤，缺乏端粒酶来维持端粒。为了研究这些非端粒酶端粒维持机制，我们使用E5 myc +mTR-/-小鼠，其遗传上缺失端粒酶（mTR）的RNA组分，并与E5 myc+小鼠杂交，其发展B细胞淋巴瘤。为了测试重组在这些非端粒酶端粒维持机制中的作用，我们目前正在使用shRNA方法来抑制各种重组基因，然后检查肿瘤生长速率的变化。为了了解更多的机制，我们检测了肿瘤的亚端粒重组。在这个提议中，我们打算研究参与复制叉停滞的基因的贡献，以及被称为断裂诱导复制的新机制对DNA修复的作用。为了监测哺乳动物细胞中断裂诱导的复制，我们将开发检测断裂诱导的复制的标志的测定法。这些特征包括杂合性丢失、非相互易位和片段重复。最后，在独立阶段，我们打算研究LINE-1逆转录转座在断裂诱导的复制和端粒维持过程中的作用。非LTR反转录转座子，称为LINE-1或L1，占小鼠和人类基因组的很大一部分。这些移动的遗传元件通过RNA中间体移动，使用一种称为靶启动逆转录的机制。此外，我们发现反转录转座也可以发生在内源性DNA断裂和功能失调的端粒。此外，果蝇中的非LTR反转录转座子完全有助于端粒维持的机制。因此，我们打算检查非LTR反转录转座子是否也有助于端粒的维护在人类和小鼠细胞，从而解释缺乏端粒酶的肿瘤的发生。 公共卫生相关性：端粒的维持可以在没有端粒酶的情况下发生，10%的人类肿瘤缺乏端粒酶活性。这些额外的机制也可以有助于表达端粒酶的肿瘤中的端粒维持，并且可能在抑制端粒酶的肿瘤中被选择。这些研究有助于理解在缺乏端粒酶的情况下发生的肿瘤发生，包括人类肉瘤和潜在的某些类型的脑肿瘤。)