HSP90 Protects the Human T-Cell Leukemia Virus Type 1 (HTLV-1) Tax Oncoprotein from Proteasomal Degradation To Support NF-κB Activation and HTLV-1 Replication
HSP90 Protects the Human T-Cell Leukemia Virus Type 1 (HTLV-1) Tax Oncoprotein from Proteasomal Degradation To Support NF-κB Activation and HTLV-1 Replication
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DOI：
10.1128/jvi.02006-13
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发表时间：
2013-12-01
影响因子：
5.4
通讯作者：
Harhaj, Edward William
中科院分区：
文献类型：
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作者：
Gao, Linlin;Harhaj, Edward William
人类T细胞白血病病毒1型（HTLV-1）是成人T细胞白血病（ATL）和HTLV-1相关性脊髓病/热带痉挛性截瘫（HAM/TSP）的病原体。HTLV-1基因组编码Tax蛋白，Tax蛋白在HTLV-1复制和T淋巴细胞的致癌转化中起重要的调节作用。尽管对Tax进行了深入的研究，但Tax如何与宿主信号通路相互作用以调节病毒复制并驱动T细胞增殖和永生化仍然知之甚少。为了获得对Tax功能和调节机制的新见解，我们使用串联亲和纯化和质谱法来鉴定新的细胞Tax相互作用蛋白。该筛选确定热休克蛋白90（HSP 90）为Tax的新结合伴侣。热休克蛋白90和税收之间的相互作用进行了验证免疫共沉淀试验，并通过共聚焦显微镜观察两种蛋白质之间的共定位。用HSP 90抑制剂17-DMAG处理HTLV-1转化细胞引起核基质中Tax的蛋白酶体降解，同时抑制NF-κ B和HTLV-1长末端重复序列（LTR）活化。慢病毒shRNAs敲低HSP 90同样引起HTLV-1转化细胞中Tax蛋白的丢失。最后，用17-DMAG处理HTLV-1转化的细胞系抑制HTLV-1复制并促进凋亡性细胞死亡。综上所述，我们的研究结果表明，Tax是一种新的HSP 90客户蛋白，HSP 90抑制剂可能对ATL和HAM/TSP患者产生治疗益处。
Human T-cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). The HTLV-1 genome encodes the Tax protein that plays essential regulatory roles in HTLV-1 replication and oncogenic transformation of T lymphocytes. Despite intensive study of Tax, how Tax interfaces with host signaling pathways to regulate virus replication and drive T-cell proliferation and immortalization remains poorly understood. To gain new insight into the mechanisms of Tax function and regulation, we used tandem affinity purification and mass spectrometry to identify novel cellular Tax-interacting proteins. This screen identified heat shock protein 90 (HSP90) as a new binding partner of Tax. The interaction between HSP90 and Tax was validated by coimmunoprecipitation assays, and colocalization between the two proteins was observed by confocal microscopy. Treatment of HTLV-1-transformed cells with the HSP90 inhibitor 17-DMAG elicited proteasomal degradation of Tax in the nuclear matrix with concomitant inhibition of NF-kappa B and HTLV-1 long terminal repeat (LTR) activation. Knockdown of HSP90 by lentiviral shRNAs similarly provoked a loss of Tax protein in HTLV-1-transformed cells. Finally, treatment of HTLV-1-transformed cell lines with 17-DMAG suppressed HTLV-1 replication and promoted apoptotic cell death. Taken together, our results reveal that Tax is a novel HSP90 client protein and HSP90 inhibitors may exert therapeutic benefits for ATL and HAM/TSP patients.