Brown Andrew C, Reddy Vishwanatha R A P, Lee Joshua, Nair Venugopal
Wellcome Trust Centre for Human Genetics, Oxford, OX3 7BN, UK.
Viral Oncogenesis Group, The Pirbright Institute, Pirbright, Surrey, GU24 0NF, UK.
Oncotarget. 2018 Jun 22;9(48):28910-28920. doi: 10.18632/oncotarget.25628.
Marek's disease (MD) is a neoplastic disease of poultry caused by Marek's disease virus (MDV), a highly contagious alphaherpesvirus. Meq, the major MDV oncoprotein, induces neoplastic transformation of T-cells through several mechanisms, including inhibition of apoptosis. In contrast, the chicken anemia virus (CAV)-encoded protein apoptin (VP3) is a powerful inducer of apoptosis of tumor cells, a property that is exploited for anticancer therapeutics. Although the molecular mechanisms of selective induction of tumor cell apoptosis by apoptin are not fully understood, its tumor cell-restricted nuclear translocation is thought to be important. Co-infection with MDV and CAV is common in many countries, CAV antigens are readily detectable in MD lymphomas, and the MDV-transformed T-lymphoblastoid cell lines such as MSB-1 is widely used for propagating CAV for vaccine production. As MDV-transformed cell lines express high levels of Meq, we examined here whether CAV-encoded apoptin interacts with Meq in these cells. Using immunofluorescence microscopy, we found that apoptin and Meq co-localize to the nucleus, and biochemical analysis indicated that the two proteins do physically interact. Using a combination of Meq mutagenesis and co-immunoprecipitation, we demonstrate that apoptin interacts with Meq within a region between amino acids 130 and 140. Results from the IncuCyte assay suggested that Meq inhibits apoptin-induced apoptosis activity. In summary, our findings indicate that Meq interacts with and inhibits apoptin. Insights into this novel interaction between Meq and apoptin will relevance for pathogenesis of coinfections of the two viruses and in CAV vaccine production using MDV-transformed cell lines.
马立克氏病（MD）是一种由马立克氏病病毒（MDV）引起的家禽肿瘤性疾病，MDV是一种高度传染性的α疱疹病毒。Meq是MDV的主要癌蛋白，通过多种机制诱导T细胞发生肿瘤转化，包括抑制细胞凋亡。相比之下，鸡贫血病毒（CAV）编码的蛋白凋亡素（VP3）是肿瘤细胞凋亡的强力诱导剂，这一特性被用于抗癌治疗。尽管凋亡素选择性诱导肿瘤细胞凋亡的分子机制尚未完全明确，但其在肿瘤细胞中的核转位被认为是重要的。MDV和CAV的共同感染在许多国家都很常见，在MD淋巴瘤中很容易检测到CAV抗原，并且MDV转化的T淋巴母细胞系如MSB-1被广泛用于繁殖CAV以生产疫苗。由于MDV转化的细胞系表达高水平的Meq，我们在此研究了CAV编码的凋亡素在这些细胞中是否与Meq相互作用。通过免疫荧光显微镜观察，我们发现凋亡素和Meq共定位于细胞核，生化分析表明这两种蛋白确实发生了物理相互作用。通过结合Meq诱变和免疫共沉淀，我们证明凋亡素与Meq在氨基酸130至140之间的区域相互作用。IncuCyte分析结果表明Meq抑制凋亡素诱导的凋亡活性。总之，我们的研究结果表明Meq与凋亡素相互作用并抑制凋亡素。对Meq与凋亡素之间这种新型相互作用的深入了解将与两种病毒共同感染的发病机制以及使用MDV转化细胞系生产CAV疫苗相关。
