MOUSE MAMMARY TUMOR VIRUS AND DETERMINANTS OF LEUKEMOGENICITY

小鼠乳腺肿瘤病毒和致白血病的决定因素

• 批准号: 6315895
• 负责人: Jaquelin Page Dudley
• 金额: $ 10.37万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-03-22 至 2005-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6315895
• 关键词: B lymphocyte; genetic regulatory element; genetically modified animals; laboratory mouse; molecular cloning; mouse leukemia; mouse mammary tumor virus; murine leukemia virus; nucleic acid repetitive sequence; open reading frames; protooncogene; provirus; recombinant virus; superantigens; transcription factor; viral carcinogenesis; virus infection mechanism; virus integration; virus related neoplasm /cancer

The mouse mammary tumor virus (MMTV) induces primarily breast cancers in mice. However, some highly related MMTV strains (e.g., TBLV) induce T-cell tumors, but not mammary carcinomas. The major differences between (LTRs) at the ends of pro-viral DNA. These differences include (i) loss of negative regulatory elements (NREs) that suppress MMTV transcription in lymphoid tissues, including thymus, (ii) loss of the C-terminal one-third of the superantigen gene that is involved in MMTV transmission from lymphoid to mammary cells, and (iii) triplication of 62 bp flanking the LTR deletion. In this grant application, regions of the TBLV genome that are responsible for thymotropism will be assessed. First, the specific cell types infected by TBLV will be analyzed, and optimal routes of infection will be determined. Second, specific mutations in known NREs, the triplicated region of the sag open reading frame will be introduced into a mammotropic MMTV and tested for their ability to infect specific cell types and to cause leukemias. Third, the triplicated region shown to enhance MMTV transcription in T-cells will be analyzed for the binding of cellular transcription factors, and these factors will be identified. Fourth, if the LTR is not sufficient to reproduce the cell-type tropism and leukemogenicity of TBLV, we will construct chimeras between mammotropic and thymotropic strains of MMTV and test these chimeras for their ability to infect different cell types and induce disease. In the second specific aim, we will continue our studies to assess the role of specific TBLV integration sites in virally-induced leukemias. Previously identified TBLV integrations will be analyzed by PCR and by pulsed field gel electrophoresis. Integrations in the c-myc locus also will be assessed in leukemias induced by MMTV pro-viruses that have a truncated sag gene and lack the NREs, but also lack the specific triplicated region found in TBLV. These experiments and studies of transgenic mice that have a mutant MMTV or TBLV LTR upstream of c-myc should provide information about whether LTR changes affect integration site choice or the ability to stimulate c-myc expression. These results should elucidate the factors conducive for the development of human leukemia and permit the development of novel strategies for their treatment.

小鼠乳腺肿瘤病毒(MMTV)主要诱发小鼠乳腺癌。然而，一些高度相关的MMTV毒株(如TBLV)会诱发T细胞肿瘤，但不会导致乳腺癌。前病毒DNA末端(LTRs)的主要差异。这些差异包括：(1)抑制包括胸腺在内的淋巴组织中MMTV转录的负调控元件(NRES)的丢失；(2)参与MMTV从淋巴样细胞向乳腺细胞传播的超抗原基因的C端1/3丢失；(3)LTR缺失两侧62个碱基的三倍体。在这项赠款申请中，将对TBLV基因组中负责嗜胸腺功能的区域进行评估。首先，将分析TBLV感染的特定细胞类型，并确定最佳感染途径。第二，已知NRES的特定突变，即SAG开放读框的三倍体区域将被引入嗜哺乳动物的MMTV，并测试它们感染特定细胞类型和导致白血病的能力。第三，将分析T细胞中显示的增强MMTV转录的三倍体区域是否与细胞转录因子结合，并鉴定这些因子。第四，如果LTR不足以复制TBLV的细胞类型嗜性和致白血病能力，我们将在MMTV嗜乳毒株和嗜胸腺株之间构建嵌合体，并测试这些嵌合体感染不同细胞类型和诱发疾病的能力。在第二个具体目标中，我们将继续我们的研究，以评估特定的TBLV整合位点在病毒诱导的白血病中的作用。先前确定的TBLV整合将通过聚合酶链式反应和脉冲场凝胶电泳法进行分析。在MMTV前病毒诱导的白血病中，c-myc基因的整合也将得到评估，这些病毒具有截短的sag基因，缺乏NRES，但也缺乏在TBLV中发现的特定三倍体区域。这些对c-myc上游有突变的MMTV或TBLV LTR的转基因小鼠的实验和研究应该提供关于LTR变化是否影响整合位点选择或刺激c-myc表达的能力的信息。这些结果应该阐明有利于人类白血病发展的因素，并允许开发新的治疗策略。