识别 α-taxilin作为B型肝炎病毒的生命周期的要素

StephenW

Identification of α-taxilin as an essential factor for the life cycle of Hepatitis B virus

    Jasmin Hoffmann a,
    Caroline Boehm a,
    Kiyoshi Himmelsbach a,
    Christian Donnerhak a,
    Hendrik Roettger a,
    Thomas S.Weiss b,
    Daniela Ploen a,
    Eberhard Hildt a, c, Corresponding author contact information, E-mail the corresponding author, E-mail the corresponding author

    a Paul-Ehrlich-Institute, Division of Virology, D-63325 Langen, Germany
    b University Hospital of Regensburg, Department of Pediatrics and Juvenile Medicine, Regensburg, Germany
    c DZIF, German center for infection research

Abstract
Background and aims

α-taxilin was identified as binding partner of syntaxins and is supposed to regulate vesicular trafficking. However, the physiological functions of α-taxilin and its potential relevance for the life cycle of hepatitis B virus (HBV) are still poorly understood.
Methods

Transfected hepatoma cells, infected primary human hepatocytes and liver tissue of HBV-infected patients were used to study the expression of α-taxilin. Subcellular localization and colocalization was analyzed by confocal laser scanning microscopy (CLSM). Protein-protein interactions were further investigated by co-immunoprecipitations. Silencing of α-taxilin expression was performed by lentiviral gene transfer.
Results

HBV producing cells show a significant higher level of α-taxilin. HBV induces, by its regulatory proteins HBx and LHBs via c-Raf the α-taxilin expression. Knockdown of α-taxilin expression specifically abolishes release of HBV virions but not the release of subviral particles. This indicates that α-taxilin is essential for the release of HBV particles. CLSM and co-immunoprecipitations demonstrated that the PreS1PreS2 domain of LHBs interacts with α-taxilin. α-taxilin harbors a YXXL motif that represents a classic late domain. In accordance to this it was found by co-immunoprecipitations that α-taxilin interacts with the ESCRT I component tsg101. CLSM revealed that a fraction of α-taxilin colocalizes with LHBs and tsg101.
Conclusion

α-taxilin plays an essential role for release of HBV-DNA containing particles. It might act as an adapter that binds on the one hand to LHBs and on the other hand to tsg101 and thereby helps to recruit the ESCRT machinery to the viral envelope proteins.
Abbreviations

    HBV, hepatitis B virus;
    CLSM, confocal laser scanning microscopy;
    LHBs, large hepatitis B virus surface antigen;
    SHBs, small …;
    ESCRT, endosomal sorting complex required for transport;
    SVP, subviral particle;
    HCC, hepatocellular carcinoma;
    RCC, renal cell carcinoma;
    MVB, multivesicular body;
    EIAV, equine infective anemia virus;
    tdn, transdominant negative

StephenW

背景和目的

α-taxilin被认定为具有约束力的合作伙伴syntaxins，应该调节水泡贩运。然而，α-taxilin和其潜在的生命周期相关的乙型肝炎病毒（HBV）的生理功能仍然知之甚少。
方法

转染肝癌细胞，感染人类原发性肝细胞和肝组织中HBV感染的患者用，研究表达α-taxilin的。亚细胞定位和共存共聚焦激光扫描显微镜（CLSM）分析。蛋白质相互作用共同免疫沉淀进一步调查。沉默α-taxilin的表达进行慢病毒基因转移。
结果

乙肝病毒产生细胞表现出显着的α-taxilin的更高层次。乙肝病毒引起，其调节蛋白HBx和LHBs的通过C-Raf的的α-taxilin表达。击倒，α-taxilin表达明确废除发布的乙肝病毒颗粒，但不亚病毒颗粒的释放。这表明，α-taxilin的是必不可少的乙肝病毒颗粒的释放。激光共聚焦显微镜和共免疫沉淀证明，，LHBs的的PreS1PreS2域相互作用与α-taxilin的。 α-taxilin怀有YXXL的图案，代表了经典的后期域。根据这个发现合作免疫沉淀，α-taxilin交互ESCRT I分量TSG101。激光共聚焦显微镜发现，一小部分α-taxilin的共定位与LHBs的和TSG101。
结论

α-taxilin的HBV-DNA含颗粒的释放起着至关重要的作用。它可能作为一个适配器，LHBs的一方面和另一方面TSG101结合，从而有助于ESCRT机械招募病毒包膜蛋白。
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