SMYD3 interacts with HTLV‐1 Tax and regulates subcellular localization of Tax
SMYD3 interacts with HTLV‐1 Tax and regulates subcellular localization of Tax
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DOI：
10.1111/j.1349-7006.2010.01752.x
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发表时间：
2011-01
期刊：
影响因子：
5.7
通讯作者：
Keiyu Yamamoto;T. Ishida;K. Nakano;Makoto Yamagishi;T. Yamochi;Yuetsu Tanaka;Y. Furukawa;Yusuke Nakamura;Toshiki Watanabe
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文献类型：
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作者：
Keiyu Yamamoto;T. Ishida;K. Nakano;Makoto Yamagishi;T. Yamochi;Yuetsu Tanaka;Y. Furukawa;Yusuke Nakamura;Toshiki Watanabe
HTLV‐1 Tax对宿主细胞的信号转导通路、基因转录和细胞周期调节的调节作用失活，主要通过其与宿主细胞因子的蛋白质-蛋白质相互作用介导。我们先前报道了Tax与组蛋白甲基转移酶（HMTase）SUV 39 H1的相互作用。由于这种相互作用是由HMTases之间共享的SUV 39 H1 SET结构域介导的，我们研究了Tax与另一种HMTase SMYD 3相互作用的可能性，SMYD 3甲基化组蛋白H3赖氨酸4并激活基因转录，并研究了功能效应。通过免疫印迹分析证实内源性SMYD 3在T细胞系和原代T细胞中的表达。共免疫沉淀试验和体外下拉试验表明Tax和SMYD 3之间存在相互作用。这种相互作用在很大程度上依赖于SMYD 3的C末端180个氨基酸，而Tax的相互作用结构域没有明确定义，尽管N末端108个氨基酸被排除了相互作用。在共转染的细胞中，Tax和SMYD 3共定位于细胞质或细胞核中。使用Tax和SMYD 3突变体的研究表明，SMYD 3主导Tax的亚细胞定位。报告基因分析显示，细胞质Tax促进的核因子-κB活化通过SMYD 3的存在而增强，并且通过shRNA介导的SMYD 3敲低而减弱，表明SMYD 3增加了Tax在细胞质中的定位水平。我们的研究首次揭示了Tax-SMYD 3的直接相互作用，以及SMYD 3对Tax的明显束缚，影响了Tax的亚细胞定位。结果表明，SMYD 3介导的Tax的核质穿梭为Tax的多效性效应提供了一个基础，该多效性效应由位于细胞质或细胞核中的细胞蛋白质的相互作用介导。（Cancer Sci 2011; 102：260-266）
HTLV‐1 Tax deregulates signal transduction pathways, transcription of genes, and cell cycle regulation of host cells, which is mainly mediated by its protein–protein interactions with host cellular factors. We previously reported an interaction of Tax with a histone methyltransferase (HMTase), SUV39H1. As the interaction was mediated by the SUV39H1 SET domain that is shared among HMTases, we examined the possibility of Tax interaction with another HMTase, SMYD3, which methylates histone H3 lysine 4 and activates transcription of genes, and studied the functional effects. Expression of endogenous SMYD3 in T cell lines and primary T cells was confirmed by immunoblotting analysis. Co‐immuno‐precipitaion assays and in vitro pull‐down assay indicated interaction between Tax and SMYD3. The interaction was largely dependent on the C‐terminal 180 amino acids of SMYD3, whereas the interacting domain of Tax was not clearly defined, although the N‐terminal 108 amino acids were dispensable for the interaction. In the cotransfected cells, colocalization of Tax and SMYD3 was indicated in the cytoplasm or nuclei. Studies using mutants of Tax and SMYD3 suggested that SMYD3 dominates the subcellular localization of Tax. Reporter gene assays showed that nuclear factor‐κB activation promoted by cytoplasmic Tax was enhanced by the presence of SMYD3, and attenuated by shRNA‐mediated knockdown of SMYD3, suggesting an increased level of Tax localization in the cytoplasm by SMYD3. Our study revealed for the first time Tax–SMYD3 direct interaction, as well as apparent tethering of Tax by SMYD3, influencing the subcellular localization of Tax. Results suggested that SMYD3‐mediated nucleocytoplasmic shuttling of Tax provides one base for the pleiotropic effects of Tax, which are mediated by the interaction of cellular proteins localized in the cytoplasm or nucleus. (Cancer Sci 2011; 102: 260–266)