Nonstructural protein precursor NS4A/B from hepatitis C virus alters function and ultrastructure of host secretory apparatus
Nonstructural protein precursor NS4A/B from hepatitis C virus alters function and ultrastructure of host secretory apparatus
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DOI：
10.1128/jvi.77.14.7843-7855.2003
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发表时间：
2003-07-01
影响因子：
5.4
通讯作者：
Kirkegaard, K
中科院分区：
文献类型：
--
作者：
Konan, KV;Giddings, TH;Kirkegaard, K
丙型肝炎病毒（HCV）的非结构蛋白以前已被证明定位于内质网（ER）时，单独表达或在其他HCV蛋白的情况下。为了确定HCV非结构蛋白的表达是否改变ER功能，我们检测了来自基因型1B HCV的NS 2/3/4A、NS 4A、NS 4 B、NS 4 A/B、NS 4 B/5A、NS 5 A和NS 5 B的表达对从ER到高尔基体的顺行运输的影响。只有名义上的前体蛋白NS 4 A/B的影响ER的高尔基体交通的速度，减缓高尔基体特异性修饰的水泡性口炎病毒G蛋白的转染表达的速度约三倍。在单独或组合表达经加工的蛋白质NS 4A和NS 4 B时，未观察到ER至高尔基体运输的这种抑制。为了确定其他货物蛋白的分泌是否被NS 4 A/B表达抑制，我们监测了在存在和不存在NS 4 A/B表达的情况下细胞表面上新合成的蛋白的出现;在存在NS 4 A/B的情况下，所有蛋白的水平都降低。这种减少也见于含有基因组长度的HCV复制子的细胞中：与治愈的细胞系相比，细胞表面上的主要组织相容性复合物I类（MHC-I）的出现率降低了三至五倍。NS 4 A/B引起的蛋白分泌抑制与导致“膜网”形成的超微结构变化无关（D. Egger等人，J. Virol. 76：5974-5984，2002），其可由单独的NS 4 B表达引起。通过减少细胞因子分泌、MHC-I呈递和将不稳定的膜蛋白转运至细胞表面，抑制整体ER至高尔基体的交通可以对宿主对HCV感染的免疫应答具有显著影响。
The nonstructural proteins of hepatitis C virus (HCV) have been shown previously to localize to the endoplasmic reticulum (ER) when expressed singly or in the context of other HCV proteins. To determine whether the expression of HCV nonstructural proteins alters ER function, we tested the effect of expression of NS2/3/4A, NS4A, NS4B, NS4A/B, NS4B/5A, NS5A, and NS5B from genotype 1b HCV on anterograde traffic from the ER to the Golgi apparatus. Only the nominal precursor protein NS4A/B affected the rate of ER-to-Golgi traffic, slowing the rate of Golgi-specific modification of the vesicular stomatitis virus G protein expressed by transfection by approximately threefold. This inhibition of ER-to-Golgi traffic was not observed upon expression of the processed proteins NS4A and NS4B, singly or in combination. To determine whether secretion of other cargo proteins was inhibited by NS4A/B expression, we monitored the appearance of newly synthesized proteins on the cell surface in the presence and absence of NS4A/B expression; levels of all were reduced in the presence of NS4A/B. This reduction is also seen in cells that contain genome length HCV replicons: the rate of appearance of major histocompatibility complex class I (MHC-I) on the cell surface was reduced by three- to fivefold compared to that for a cured cell line. The inhibition of protein secretion caused by NS4A/B does not correlate with the ultrastructural changes leading to the formation a "membranous web" (D. Egger et al., J. Virol. 76:5974-5984, 2002), which can be caused by expression of NS4B alone. Inhibition of global ER-to-Golgi traffic could, by reducing cytokine secretion, MHC-I presentation, and transport of labile membrane proteins to the cell surface, have significant effects on the host immune response to HCV infection.