Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, USA.
Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, USA.
J Virol. 2020 Jul 1;94(14). doi: 10.1128/JVI.01784-19.
Expression of viral genes and activation of innate antiviral responses during infection result in an increase in reactive oxygen species (ROS) and toxic by-products of energy metabolism which can lead to cell death. The mitochondrion and its associated proteins are crucial regulators of these responses and related pathways such as autophagy and apoptosis. Through a mass spectrometry approach, we have shown that the herpes simplex virus 1 (HSV-1) neurovirulence- and autophagy-modulating protein ICP34.5 interacts with numerous mitochondrion-associated factors. Specifically, we showed that amino acids 68 to 87 of ICP34.5, the domain that binds beclin1 and controls neurovirulence, are necessary for interactions with PGAM5, KEAP1, and other regulators of the antioxidant response, mitochondrial trafficking, and programmed cell death. We further show that while this domain interacts with multiple cellular stress response factors, it does not alter apoptosis or antioxidant gene expression. That said, the attenuated replication of a recombinant virus lacking residues 68 to 87 (termed Δ68-87) in primary human fibroblasts was restored by addition of ferric nitrate. Furthermore, in primary mouse neurons, the perinuclear localization of mitochondria that follows infection with HSV-1 was notably absent following Δ68-87 infection. Through this 20-amino-acid domain, ICP34.5 significantly reduces mitochondrial motility in axons of neurons. We propose the hypothesis that ICP34.5 promotes perinuclear mitochondrial localization by modulating transport of mitochondria through interaction with PGAM5. These data expand upon previous observations of altered mitochondrial dynamics following alphaherpesvirus infections and identify a key determinant of this activity during HSV-1 infections. Herpes simplex virus persists lifelong in neurons and can reactivate to cause recurrent lesions in mucosal tissues. A key determinant of virulence is the viral protein ICP34.5, of which residues 68 to 87 significantly contribute to neurovirulence through an unknown mechanism. Our report provides evidence that residues 68 to 87 of ICP34.5 are required for binding mitochondrion-associated factors. These interactions alter mitochondrial dynamics in neurons, thereby facilitating viral replication and pathogenesis.
病毒基因的表达和先天抗病毒反应的激活导致活性氧（ROS）和能量代谢的有毒副产物增加，从而导致细胞死亡。线粒体及其相关蛋白是这些反应和相关途径（如自噬和细胞凋亡）的关键调节剂。通过质谱分析方法，我们已经表明单纯疱疹病毒 1（HSV-1）的神经毒力和自噬调节蛋白 ICP34.5 与许多与线粒体相关的因子相互作用。具体来说，我们表明 ICP34.5 的氨基酸 68 到 87，即与 beclin1 结合并控制神经毒力的结构域，是与 PGAM5、KEAP1 和其他抗氧化反应、线粒体运输和程序性细胞死亡调节剂相互作用所必需的。我们进一步表明，虽然这个结构域与多种细胞应激反应因子相互作用，但它不会改变细胞凋亡或抗氧化基因的表达。也就是说，在原代人成纤维细胞中，缺乏氨基酸 68 到 87 的重组病毒（称为 Δ68-87）的复制能力减弱，但通过添加硝酸铁得到了恢复。此外，在原代小鼠神经元中，感染 HSV-1 后，核周线粒体的定位明显缺失。通过这个 20 个氨基酸的结构域，ICP34.5 显著降低了神经元轴突中线粒体的运动性。我们提出假说，ICP34.5 通过与 PGAM5 相互作用调节线粒体的运输，从而促进核周线粒体的定位。这些数据扩展了先前关于α疱疹病毒感染后线粒体动力学改变的观察结果，并确定了 HSV-1 感染期间这种活性的关键决定因素。单纯疱疹病毒在神经元中终身存在，并可重新激活导致粘膜组织的复发性病变。毒力的一个关键决定因素是病毒蛋白 ICP34.5，其氨基酸 68 到 87 通过未知机制对神经毒力有显著贡献。我们的报告提供了证据，表明 ICP34.5 的氨基酸 68 到 87 是与线粒体相关因子结合所必需的。这些相互作用改变了神经元中线粒体的动力学，从而促进了病毒的复制和发病机制。
