Heat Shock Protein 70 Regulates Degradation of the Mumps Virus Phosphoprotein via the Ubiquitin-Proteasome Pathway
Heat Shock Protein 70 Regulates Degradation of the Mumps Virus Phosphoprotein via the Ubiquitin-Proteasome Pathway
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DOI：
10.1128/jvi.03343-14
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发表时间：
2015-03-01
影响因子：
5.4
通讯作者：
Kidokoro, Minoru
中科院分区：
文献类型：
--
作者：
Katoh, Hiroshi;Kubota, Toru;Kidokoro, Minoru
腮腺炎病毒（MuV）感染诱导细胞质包涵体（IBs）的形成。越来越多的证据表明，IBs是RNA病毒合成病毒RNA的位点。然而，在MuV感染的情况下，对IBs的病毒和细胞组成以及生物学功能知之甚少。本研究通过拉下纯化和n端氨基酸测序发现，应激诱导热休克蛋白70 （Hsp72）是MuV磷酸化蛋白（P蛋白）的结合伙伴，而P蛋白是IB形成的重要组成部分。免疫荧光和免疫印迹分析显示，Hsp72在IBs中与P蛋白共定位，并且在MuV感染期间其表达增加。使用小干扰rna （sirna）敲除Hsp72对培养细胞中的病毒繁殖几乎没有影响。敲低Hsp72可引起泛素化P蛋白的积累和延迟P蛋白的降解。这些结果表明，Hsp72被招募到IBs中，并通过泛素-蛋白酶体途径调节MuV P蛋白的降解。胞质包涵体（IBs）的形成是单核病毒感染的一个共同特征。IBs被认为是病毒RNA复制和转录的位点。然而，很少有研究关注宿主因子招募到IBs及其生物学功能。在这里，我们发现应激诱导热休克蛋白70 （Hsp72）是腮腺炎病毒（MuV）磷蛋白（P蛋白）的第一个细胞伴侣，这是IBs的重要组成部分，参与病毒RNA复制/转录。我们发现动员到IBs的Hsp72通过泛素-蛋白酶体途径促进了MuV P蛋白的降解。我们的数据为肠易激菌在单胞病毒感染中所起的作用提供了新的见解。
Mumps virus (MuV) infection induces formation of cytoplasmic inclusion bodies (IBs). Growing evidence indicates that IBs are the sites where RNA viruses synthesize their viral RNA. However, in the case of MuV infection, little is known about the viral and cellular compositions and biological functions of the IBs. In this study, pulldown purification and N-terminal amino acid sequencing revealed that stress-inducible heat shock protein 70 (Hsp72) was a binding partner of MuV phosphoprotein (P protein), which was an essential component of the IB formation. Immunofluorescence and immunoblotting analyses revealed that Hsp72 was colocalized with the P protein in the IBs, and its expression was increased during MuV infection. Knockdown of Hsp72 using small interfering RNAs (siRNAs) had little, if any, effect on viral propagation in cultured cells. Knockdown of Hsp72 caused accumulation of ubiquitinated P protein and delayed P protein degradation. These results show that Hsp72 is recruited to IBs and regulates the degradation of MuV P protein through the ubiquitin-proteasome pathway.IMPORTANCEFormation of cytoplasmic inclusion bodies (IBs) is a common characteristic feature in mononegavirus infections. IBs are considered to be the sites of viral RNA replication and transcription. However, there have been few studies focused on host factors recruited to the IBs and their biological functions. Here, we identified stress-inducible heat shock protein 70 (Hsp72) as the first cellular partner of mumps virus (MuV) phosphoprotein (P protein), which is an essential component of the IBs and is involved in viral RNA replication/transcription. We found that the Hsp72 mobilized to the IBs promoted degradation of the MuV P protein through the ubiquitin-proteasome pathway. Our data provide new insight into the role played by IBs in mononegavirus infection.