Retrovirus Gene Regulation: HTLV-1 Transmission and Repl

逆转录病毒基因调控：HTLV-1 传输和复制

• 批准号: 7338201
• 负责人: DAVID DERSE
• 金额: --
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7338201
• 关键词: Retrovirus; Gene; Regulation; HTLV; Transmission

The molecular mechanisms underlying the steps of the human T-cell leukemia virus type 1 (HTLV-1) infectious cycle are poorly understood. Experimental and epidemiological evidence supports a model in which HTLV-1 is transmitted directly between T lymphocytes. We predict that virus assembly, release, transmission, and replication are coordinated with cell-cell adhesion events. Thus, we are examining the components and pathways that control dissemination and replication of HTLV-1 in cell culture model systems. Biochemical, functional, and electron microscopic methods revealed that a peptide motif in the matrix domain of HTLV-1 Gag is bound by a cellular NEDD4-family ubiquitin ligase (WWP1) that is involved in membrane protein trafficking. Ubiquitination of the viral Gag protein by WWP1 is an essential early step in virion assembly and release. We also showed that HTLV-1 Gag protein is targeted to tetraspanin enriched microdomains (TEMs) in the plasma membrane. In fact, HTLV-1 Gag interacts with the cytoplasmic loop of the tetraspanins CD81 and CD82. This finding is important, because tetraspanins help organize cell surface adhesion proteins and play important roles in cell adhesion and signal transduction. The association of HTLV-1 virion components with tetraspanins and other cell surface and cytoskeletal proteins may be necessary to direct virion transmission to sites of cell-cell adhesion. After entry into the target cell, the viral enzymes and structural proteins form a replication complex that converts the single-stranded viral genomic RNA into a double-stranded DNA, which is then integrated into the host cell chromosome. We have developed cell culture systems, infectious molecular clones, and viral vectors in order to study mechanisms of HTLV-1 infection and to determine whether cellular factors can enhance or restrict replication. We have also characterized the virion-associated reverse transcriptase and have begun to define the properties of the recombinant protein. We are studying the mechanisms that HTLV-1 has evolved to evade cellular defense mechanisms that restrict the replication of other retroviruses. We have shown that HTLV-1 counteracts the antiviral effects of APOBEC3G by a cis-acting virion exclusion mechanism, which is very different compared with the way HIV-1 evades APOBEC3G. In contrast to HIV-1, HTLV-1 was not sensitive to restriction by cellular TRIM5alpha or other TRIM proteins. Although the basic schemes for transmission and replication are conserved among retroviruses, variations on common themes are likely to reveal important insights into the strategies that different viruses use for propagation and persistence in vivo. In this respect, it is useful to compare HTLV-1 and HIV-1, because both are T-cell-tropic retroviruses whose very different biological properties may be traced back to divergent strategies for escaping host-mediated immune and cellular defense mechanisms.

人类 T 细胞白血病病毒 1 型 (HTLV-1) 感染周期的分子机制尚不清楚。实验和流行病学证据支持 HTLV-1 在 T 淋巴细胞之间直接传播的模型。我们预测病毒的组装、释放、传播和复制与细胞间粘附事件相协调。因此，我们正在研究细胞培养模型系统中控制 HTLV-1 传播和复制的成分和途径。生化、功能和电子显微镜方法表明，HTLV-1 Gag 基质结构域中的肽基序与参与膜蛋白运输的细胞 NEDD4 家族泛素连接酶 (WWP1) 结合。 WWP1 对病毒 Gag 蛋白的泛素化是病毒粒子组装和释放的重要早期步骤。我们还表明，HTLV-1 Gag 蛋白靶向质膜​​中富含四跨膜蛋白的微结构域 (TEM)。事实上，HTLV-1 Gag 与四跨膜蛋白 CD81 和 CD82 的细胞质环相互作用。这一发现很重要，因为四跨膜蛋白有助于组织细胞表面粘附蛋白，并在细胞粘附和信号转导中发挥重要作用。 HTLV-1 病毒体成分与四跨膜蛋白以及其他细胞表面和细胞骨架蛋白的结合可能对于引导病毒体传播到细胞-细胞粘附位点是必要的。进入靶细胞后，病毒酶和结构蛋白形成复制复合物，将单链病毒基因组RNA转化为双链DNA，然后整合到宿主细胞染色体中。我们开发了细胞培养系统、感染性分子克隆和病毒载体，以研究 HTLV-1 感染机制并确定细胞因子是否可以增强或限制复制。我们还表征了病毒体相关逆转录酶，并开始定义重组蛋白的特性。我们正在研究 HTLV-1 的进化机制，以逃避限制其他逆转录病毒复制的细胞防御机制。我们已经证明，HTLV-1通过顺式病毒颗粒排除机制抵消APOBEC3G的抗病毒作用，这与HIV-1逃避APOBEC3G的方式有很大不同。与 HIV-1 相比，HTLV-1 对细胞 TRIM5α 或其他 TRIM 蛋白的限制不敏感。尽管传播和复制的基本方案在逆转录病毒中是保守的，但共同主题的变化可能揭示不同病毒在体内传播和持续存在的策略的重要见解。在这方面，比较 HTLV-1 和 HIV-1 是有用的，因为两者都是 T 细胞嗜性逆转录病毒，其非常不同的生物学特性可能可以追溯到逃避宿主介导的免疫和细胞防御机制的不同策略。