Buckingham Erin M, Carpenter John E, Jackson Wallen, Zerboni Leigh, Arvin Ann M, Grose Charles
Virology Laboratory, Department of Pediatrics, University of Iowa Children's Hospital, Iowa City, IA 52242; and.
Departments of Pediatrics and Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305.
Proc Natl Acad Sci U S A. 2015 Jan 6;112(1):256-61. doi: 10.1073/pnas.1417878112. Epub 2014 Dec 22.
Autophagy is a process by which misfolded and damaged proteins are sequestered into autophagosomes, before degradation in and recycling from lysosomes. We have extensively studied the role of autophagy in varicella-zoster virus (VZV) infection, and have observed that vesicular cells are filled with >100 autophagosomes that are easily detectable after immunolabeling for the LC3 protein. To confirm our hypothesis that increased autophagosome formation was not secondary to a block, we examined all conditions of VZV infection as well as carrying out two assessments of autophagic flux. We first investigated autophagy in human skin xenografts in the severe combined immunodeficiency (SCID) mouse model of VZV pathogenesis, and observed that autophagosomes were abundant in infected human skin tissues. We next investigated autophagy following infection with sonically prepared cell-free virus in cultured cells. Under these conditions, autophagy was detected in a majority of infected cells, but was much less than that seen after an infected-cell inoculum. In other words, inoculation with lower-titered cell-free virus did not reflect the level of stress to the VZV-infected cell that was seen after inoculation of human skin in the SCID mouse model or monolayers with higher-titered infected cells. Finally, we investigated VZV-induced autophagic flux by two different methods (radiolabeling proteins and a dual-colored LC3 plasmid); both showed no evidence of a block in autophagy. Overall, therefore, autophagy within a VZV-infected cell was remarkably different from autophagy within an HSV-infected cell, whose genome contains two modifiers of autophagy, ICP34.5 and US11, not present in VZV.
自噬是一个过程，通过该过程，错误折叠和受损的蛋白质被隔离到自噬体中，然后在溶酶体中降解并循环利用。我们广泛研究了自噬在水痘带状疱疹病毒（VZV）感染中的作用，并观察到水疱细胞中充满了100多个自噬体，在用LC3蛋白进行免疫标记后很容易检测到。为了证实我们的假设，即自噬体形成增加不是继发于阻断，我们检查了VZV感染的所有条件，并对自噬通量进行了两项评估。我们首先在VZV发病机制的严重联合免疫缺陷（SCID）小鼠模型中的人皮肤异种移植中研究自噬，观察到感染的人皮肤组织中自噬体丰富。接下来，我们在用超声处理的无细胞病毒感染培养细胞后研究自噬。在这些条件下，大多数感染细胞中检测到自噬，但比感染细胞接种物后观察到的要少得多。换句话说，用低滴度无细胞病毒接种并不能反映在SCID小鼠模型中接种人皮肤或用高滴度感染细胞接种单层后VZV感染细胞所承受的应激水平。最后，我们通过两种不同的方法（放射性标记蛋白质和双色LC3质粒）研究了VZV诱导的自噬通量；两者均未显示出自噬阻断的证据。因此，总体而言，VZV感染细胞内的自噬与HSV感染细胞内的自噬显著不同，HSV的基因组包含两个自噬调节剂ICP34.5和US11，而VZV中不存在。
