Murine γ-herpesvirus 68 latency protein M2 binds to Vav signaling proteins and inhibits B-cell receptor-induced cell cycle arrest and apoptosis in WEHI-231 B cells
Murine γ-herpesvirus 68 latency protein M2 binds to Vav signaling proteins and inhibits B-cell receptor-induced cell cycle arrest and apoptosis in WEHI-231 B cells
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DOI：
10.1074/jbc.m507478200
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发表时间：
2005-11-11
影响因子：
4.8
通讯作者：
Eric, WF
中科院分区：
文献类型：
--
作者：
Madureira, PA;Matos, P;Eric, WF
MHV-68潜伏蛋白M2与任何已知的病毒或细胞蛋白都没有同源性，其功能尚不清楚。为了明确M2在MHV-68潜伏期中所起的作用及其分子机制，我们以M2为诱饵筛选了酵母双杂交小鼠B细胞cDNA文库。在两个独立的筛选中，Vav1被鉴定为M2相互作用蛋白。随后的酵母双杂交相互作用研究表明，M2也与Vav2结合，但不与Vav3结合，位于M2 C末端的三个“PXXP”基序对这种相互作用是重要的。免疫共沉淀法在293T和WEHI-231 B细胞中也证实了M2和Vav蛋白之间的相互作用。Rac1/GST-PAK“下拉”实验和使用磷酸化Vav抗体的Western印迹分析表明，M2在WEHI-231细胞中的表达增强了Vav的活性。我们在WEHI-231细胞中进一步表明，M2的表达促进了细胞的增殖和存活，并与增强的细胞周期蛋白D2和抑制的p27(Kip1)、p130和Bim的表达有关。综上所述，这些实验表明，M2在潜伏期的建立和维持过程中可能通过调节B细胞受体介导的信号事件来促进B细胞的激活、增殖和存活，从而在传播潜伏病毒方面发挥重要作用。
The MHV-68 latent protein, M2, does not have homology to any known viral or cellular proteins, and its function is unclear. To define the role played by M2 during MHV-68 latency as well as the molecular mechanism involved, we used M2 as bait to screen a yeast two-hybrid mouse B-cell cDNA library. Vav1 was identified as an M2-interacting protein in two independent screenings. Subsequent yeast two-hybrid interaction studies showed that M2 also binds to Vav2, but not Vav3, and that three "PXXP" motifs located at the C terminus of M2 are important for this interaction. The interactions between M2 and Vav proteins were also confirmed in vivo in 293T and WEHI-231 B-cells by co-immunoprecipitation assays. Rac1/ GST-PAK "pull-down" experiments and Western blot analysis using a phospho-Vav antibody demonstrated that expression of M2 in WEHI-231 cells enhances Vav activity. We further showed in WEHI-231 cells that M2 expression promotes proliferation and survival and is associated with enhanced cyclin D2 and repressed p27(Kip1), p130, and Bim expression. Taken together, these experiments suggest that M2 might have an important role in disseminating the latent virus during the establishment and maintenance of latency by modulating B-cell receptor-mediated signaling events through Vav to promote B-cell activation, proliferation, and survival.