Nuclear Trafficking of the Retroviral Gag Protein

逆转录病毒 Gag 蛋白的核运输

• 批准号: 6611470
• 负责人: Leslie J Parent
• 金额: $ 27.64万
• 依托单位: PENNSYLVANIA STATE UNIV HERSHEY MED CTR
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-07-01 至 2008-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6611470
• 关键词: Rous sarcoma virus; cell nucleus; gag protein; gene mutation; intracellular transport; protein localization; protein structure function; protein transport; tissue /cell culture; transport proteins; virus RNA; virus infection mechanism; virus integration; virus replication

DESCRIPTION (provided by applicant): Retroviruses cause incurable malignancies and immunodeficiency diseases in animals and humans. The avian pathogen Rous sarcoma virus (RSV), the first virus linked to cancer, is the prototypic oncoretrovirus, and its use as a model system has led to significant advances in understanding the human retroviruses HIV and HTLV-I. All retroviruses must gain access to the nucleus in order to establish infection. Following reverse transcription of the RNA genome in the cytoplasm, the preintegration complex (PIC) enters the nucleus. In RSV and lentiviruses including HIV, nuclear entry appears to be an active process, as mitosis is not absolutely required. This process of nuclear import is one of the least understood aspects of the viral life cycle. In the previous funding period, we identified a nuclear import signal in the matrix (MA) domain of the RSV Gag protein, raising the possibility that MA might play a role in nuclear import of the PIC. In addition, we found that the nuclear import signal in MA mediates nuclear localization of the Gag polyprotein during the assembly phase of the replication cycle, and a CRMl-dependent nuclear export signal in the p10 sequence returns Gag to the cytosol. Interestingly, a mutant Gag protein that is defective in viral RNA packaging bypasses the nuclear compartment, suggesting a functional link between the nuclear trafficking of Gag and encapsidation of viral RNA. The major goal of the current proposal is to capitalize on these pivotal findings as a means to elucidate (1) the viral factors that control nucleocytoplasmic trafficking of Gag, (2) host cofactors that mediate nuclear entry and egress of Gag, and (3) the functional significance of transient nuclear localization of Gag. In the first Specific Aim, we propose to define the NLS in MA, the mechanism of nuclear entry, and the cellular pathways used for import. In Aim 2, the Gag NES will be characterized and host factors that mediate export will be identified. Specific Aim 3 focuses on testable hypotheses that address the role of MA and Gag proteins in nuclear import of the PIC and selection of genomic viral RNA for packaging into virions. Through these studies, we expect to gain insight into the essential but poorly understood mechanisms underlying viral nuclear entry and RNA encapsidation. By elucidating a fundamental pathway critical for virus replication, we hope to find targets for a new class of agents to combat retroviral diseases.

描述（由申请人提供）：逆转录病毒会在动物和人类中引起无法治愈的恶性肿瘤和免疫缺陷疾病。禽类病原体劳斯肉瘤病毒 (RSV) 是第一种与癌症相关的病毒，是典型的癌逆转录病毒，其作为模型系统的使用使人们在了解人类逆转录病毒 HIV 和 HTLV-I 方面取得了重大进展。所有逆转录病毒都必须进入细胞核才能建立感染。 RNA 基因组在细胞质中逆转录后，预整合复合物 (PIC) 进入细胞核。在 RSV 和慢病毒（包括 HIV）中，进入核似乎是一个活跃的过程，因为有丝分裂不是绝对需要的。这种核输入过程是病毒生命周期中最不为人所知的方面之一。在之前的资助期间，我们在 RSV Gag 蛋白的基质 (MA) 结构域中发现了核输入信号，这提高了 MA 可能在 PIC 核输入中发挥作用的可能性。此外，我们发现MA中的核输入信号在复制周期的组装阶段介导Gag多蛋白的核定位，并且p10序列中的CRM1依赖性核输出信号将Gag返回至胞质溶胶。有趣的是，病毒RNA包装中有缺陷的突变Gag蛋白绕过核区室，表明Gag的核运输和病毒RNA衣壳化之间存在功能联系。当前提案的主要目标是利用这些关键发现作为阐明（1）控制 Gag 核细胞质运输的病毒因子，（2）介导 Gag 核进出核的宿主辅助因子，以及（3）的手段。 Gag 瞬时核定位的功能意义。在第一个具体目标中，我们建议定义 MA 中的 NLS、核进入机制以及用于输入的细胞途径。在目标 2 中，将描述 Gag NES 的特征，并确定介导输出的宿主因素。具体目标 3 侧重于可测试的假设，这些假设涉及 MA 和 Gag 蛋白在 PIC 核导入和选择基因组病毒 RNA 包装到病毒颗粒中的作用。通过这些研究，我们希望深入了解病毒进入核和 RNA 衣壳化的基本但人们知之甚少的机制。通过阐明对病毒复制至关重要的基本途径，我们希望找到对抗逆转录病毒疾病的新型药物的靶点。