Zhao Yuguang, Kurian Dominic, Xu Hongtao, Petherbridge Lawrence, Smith Lorraine P, Hunt Lawrence, Nair Venugopal
Viral Oncogenesis Group, Institute for Animal Health, Compton RG20 7NN, UK.
J Gen Virol. 2009 Sep;90(Pt 9):2201-8. doi: 10.1099/vir.0.012062-0. Epub 2009 Jun 3.
Marek's disease virus (MDV) is a highly oncogenic alphaherpesvirus that induces the rapid onset of T-cell lymphomas in poultry. The MDV-encoded oncoprotein Meq plays an important role in oncogenicity, as its deletion abolishes the ability of the virus to induce tumours. It has been shown previously that Meq oncogenicity is linked to its interaction with C-terminal binding protein 1 (CtBP), a property also shared by other virus-encoded oncoproteins such as adenovirus E1A and Epstein-Barr virus EBNA3A and -3C. Therefore, this study examined whether Meq also shares the properties of these viral oncoproteins in interacting with other binding partners such as heat-shock protein 70 (Hsp70), a molecular chaperone protein linked to multiple cellular functions including neoplastic transformation. Confocal microscopic analysis demonstrated that MDV infection induced nuclear accumulation of Hsp70 and its co-localization with Meq. Biochemical evidence of Meq-Hsp70 interaction was obtained by two-way immunoprecipitation with Meq- and Hsp70-specific antibodies. To demonstrate further the Meq-Hsp70 interaction in virus-induced lymphomas, recombinant MDV was generated expressing an N-terminal tandem affinity purification (TAP) tag-fused Meq by mutagenesis of the infectious BAC clone of the oncogenic MDV strain RB-1B. Demonstration of Hsp70 in the TAP-tag affinity purified Meq from tumours induced by the recombinant virus, using quadrupole time-of-flight tandem mass spectrometry analysis, further confirmed the Meq-Hsp70 interaction in the transformed lymphocytes. Given the well-documented evidence of the tumorigenic properties of Hsp70 and its interaction with a number of other known viral oncoproteins, demonstration of the interaction of Meq and Hsp70 is significant in MDV oncogenesis.
马立克氏病病毒（MDV）是一种高度致癌的α疱疹病毒，可在家禽中迅速诱发T细胞淋巴瘤。MDV编码的癌蛋白Meq在致癌性中起重要作用，因为其缺失会消除病毒诱导肿瘤的能力。先前已表明，Meq的致癌性与其与C端结合蛋白1（CtBP）的相互作用有关，其他病毒编码的癌蛋白如腺病毒E1A和爱泼斯坦-巴尔病毒EBNA3A及-3C也具有这一特性。因此，本研究检测了Meq在与其他结合伴侣（如热休克蛋白70（Hsp70））相互作用时是否也具有这些病毒癌蛋白的特性，Hsp70是一种分子伴侣蛋白，与包括肿瘤转化在内的多种细胞功能相关。共聚焦显微镜分析表明，MDV感染诱导Hsp70在细胞核中积累并与Meq共定位。通过用Meq和Hsp70特异性抗体进行双向免疫沉淀，获得了Meq-Hsp70相互作用的生化证据。为了进一步证明病毒诱导的淋巴瘤中Meq-Hsp70的相互作用，通过对致癌MDV株RB-1B的感染性BAC克隆进行诱变，构建了表达N端串联亲和纯化（TAP）标签融合Meq的重组MDV。使用四极杆飞行时间串联质谱分析，在重组病毒诱导的肿瘤中TAP标签亲和纯化的Meq中检测到Hsp70，进一步证实了转化淋巴细胞中Meq-Hsp70的相互作用。鉴于Hsp70的致瘤特性及其与许多其他已知病毒癌蛋白相互作用的充分证据，Meq与Hsp70相互作用的证明在MDV致癌过程中具有重要意义。
