Interaction of the hepatitis B virus X protein with the lysine methyltransferase SET and MYND domain-containing 3 induces activator protein 1 activation
Interaction of the hepatitis B virus X protein with the lysine methyltransferase SET and MYND domain-containing 3 induces activator protein 1 activation
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DOI：
10.1111/1348-0421.12345
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发表时间：
2016-01-01
影响因子：
2.6
通讯作者：
Hotta, Hak
中科院分区：
文献类型：
--
作者：
Hayashi, Miwako;Deng, Lin;Hotta, Hak
B型肝炎病毒（HBV）是一种广泛存在于人类的病原体，常引起慢性肝炎、肝硬化和肝细胞癌。HBV发病机制的详细机制仍然知之甚少。HBV X蛋白（HBx）是一种多功能调节因子，通过与多种宿主因子相互作用调节病毒复制和宿主细胞功能，如细胞周期进程、凋亡和蛋白质降解。最近，丙型肝炎病毒的非结构蛋白5A（NS 5A）已被报道与甲基转移酶SET和MYND结构域3（SMYD 3）相互作用，这与染色质修饰和癌症的发展有关。由于HBx与NS 5A共享关于病毒复制和发病机制的基本调节功能，因此决定检查HBx是否与SMYD 3相互作用。在本研究中，通过免疫共沉淀分析证明HBx与Huh-7.5细胞中异位和内源性表达的SMYD 3相互作用。缺失突变分析表明，HBx的C-末端区域（氨基酸[aa] 131-154）和SMYD 3的内部区域（aa 269-288）负责它们的相互作用。免疫荧光和邻位连接分析表明，HBx和SMYD 3共定位主要在细胞质中。荧光素酶报告基因分析表明，HBx和SMYD 3之间的相互作用激活激活蛋白1（AP-1）信号，但不激活核因子-κ B（NF-κ B）信号。另一方面，SMYD 3的过表达或敲低均不改变HBV转录物和HBV表面抗原（HBsAg）的产生。总之，一种新的HBx相互作用蛋白，SMYD 3，被确定，导致在HBV感染的细胞中AP-1激活的新机制的建议。
Hepatitis B virus (HBV) is a widespread human pathogen that often causes chronic hepatitis, liver cirrhosis and hepatocellular carcinoma. The detailed mechanisms underlying HBV pathogenesis remain poorly understood. The HBV X protein (HBx) is a multifunctional regulator that modulates viral replication and host cell functions, such as cell cycle progression, apoptosis and protein degradation through interaction with a variety of host factors. Recently, the nonstructural protein 5A (NS5A) of hepatitis C virus has been reported to interact with methyltransferase SET and MYND domain-containing 3 (SMYD3), which is implicated in chromatin modification and development of cancer. Because HBx shares fundamental regulatory functions concerning viral replication and pathogenesis with NS5A, it was decided to examine whether HBx interacts with SMYD3. In the present study, it was demonstrated by co-immunoprecipitation analysis that HBx interacts with both ectopically and endogenously expressed SMYD3 in Huh-7.5 cells. Deletion mutation analysis revealed that the C-terminal region of HBx (amino acids [aa] 131-154) and an internal region of SMYD3 (aa 269-288) are responsible for their interaction. Immunofluorescence and proximity ligation assays showed that HBx and SMYD3 co-localize predominantly in the cytoplasm. Luciferase reporter assay demonstrated that the interaction between HBx and SMYD3 activates activator protein 1 (AP-1) signaling, but not that of nuclear factor-kappa B (NF-kappa B). On the other hand, neither overexpression nor knockdown of SMYD3 altered production of HBV transcripts and HBV surface antigen (HBsAg). In conclusion, a novel HBx-interacting protein, SMYD3, was identified, leading to proposal of a novel mechanism of AP-1 activation in HBV-infected cells.