State Key Laboratory of Veterinary Etiological Biology, National Foot and Mouth Diseases Reference Laboratory, Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China.
State Key Laboratory of Veterinary Etiological Biology, National Foot and Mouth Diseases Reference Laboratory, Key Laboratory of Animal Virology of Ministry of Agriculture, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, Gansu, China
J Virol. 2019 Jun 14;93(13). doi: 10.1128/JVI.00588-19. Print 2019 Jul 1.
DnaJ heat shock protein family (Hsp40) member A3 (DNAJA3) plays an important role in viral infections. However, the role of DNAJA3 in replication of foot-and-mouth-disease virus (FMDV) remains unknown. In this study, DNAJA3, a novel binding partner of VP1, was identified using yeast two-hybrid screening. The DNAJA3-VP1 interaction was further confirmed by coimmunoprecipitation and colocalization in FMDV-infected cells. The J domain of DNAJA3 (amino acids 1 to 168) and the lysine at position 208 (K208) of VP1 were shown to be critical for the DNAJA3-VP1 interaction. Overexpression of DNAJA3 dramatically dampened FMDV replication, whereas loss of function of DNAJA3 elicited opposing effects against FMDV replication. Mechanistical study demonstrated that K208 of VP1 was critical for reducing virus titer caused by DNAJA3 using K208A mutant virus. DNAJA3 induced lysosomal degradation of VP1 by interacting with LC3 to enhance the activation of lysosomal pathway. Meanwhile, we discovered that VP1 suppressed the beta interferon (IFN-β) signaling pathway by inhibiting the phosphorylation, dimerization, and nuclear translocation of IRF3. This inhibitory effect was considerably boosted in DNAJA3-knockout cells. In contrast, overexpression of DNAJA3 markedly attenuated VP1-mediated suppression on the IFN-β signaling pathway. Poly(I⋅C)-induced phosphorylation of IRF3 was also decreased in DNAJA3-knockout cells compared to that in the DNAJA3-WT cells. In conclusion, our study described a novel role for DNAJA3 in the host's antiviral response by inducing the lysosomal degradation of VP1 and attenuating the VP1-induced suppressive effect on the IFN-β signaling pathway. This study pioneeringly determined the antiviral role of DNAJA3 in FMDV. DNAJA3 was found to interact with FMDV VP1 and trigger its degradation via the lysosomal pathway. In addition, this study is also the first to clarify the mechanism by which VP1 suppressed IFN-β signaling pathway by inhibiting the phosphorylation, dimerization, and nuclear translocation of IRF3. Moreover, DNAJA3 significantly abrogated VP1-induced inhibitive effect on the IFN-β signaling pathway. These data suggested that DNAJA3 plays an important antiviral role against FMDV by both degrading VP1 and restoring of IFN-β signaling pathway.
DNAJ 热休克蛋白家族（Hsp40）成员 A3（DNAJA3）在病毒感染中发挥重要作用。然而，DNAJA3 在口蹄疫病毒（FMDV）复制中的作用尚不清楚。在这项研究中，通过酵母双杂交筛选鉴定出 VP1 的新型结合伴侣 DNAJA3。DNAJA3-VP1 相互作用通过共免疫沉淀和在 FMDV 感染细胞中的共定位进一步得到证实。DNAJA3 的 J 结构域（氨基酸 1 至 168）和 VP1 位置 208 的赖氨酸（K208）对于 DNAJA3-VP1 相互作用至关重要。DNAJA3 的过表达显著抑制 FMDV 复制，而 DNAJA3 的功能丧失则对 FMDV 复制产生相反的影响。机制研究表明，VP1 的 K208 对于使用 K208A 突变病毒降低 DNAJA3 引起的病毒滴度至关重要。DNAJA3 通过与 LC3 相互作用诱导 VP1 的溶酶体降解，从而增强溶酶体途径的激活。同时，我们发现 VP1 通过抑制 IRF3 的磷酸化、二聚化和核易位来抑制β干扰素（IFN-β）信号通路。在 DNAJA3 敲除细胞中，这种抑制作用得到了显著增强。相比之下，DNAJA3 的过表达显著减弱了 VP1 介导的对 IFN-β 信号通路的抑制作用。与 DNAJA3-WT 细胞相比，多聚（I·C）诱导的 IRF3 磷酸化也在 DNAJA3 敲除细胞中减少。总之，本研究通过诱导 VP1 的溶酶体降解并减弱 VP1 诱导的对 IFN-β 信号通路的抑制作用，描述了 DNAJA3 在宿主抗病毒反应中的新作用。本研究首次确定了 DNAJA3 在 FMDV 中的抗病毒作用。发现 DNAJA3 与 FMDV VP1 相互作用，并通过溶酶体途径触发其降解。此外，本研究还首次阐明了 VP1 通过抑制 IRF3 的磷酸化、二聚化和核易位来抑制 IFN-β 信号通路的机制。此外，DNAJA3 显著削弱了 VP1 诱导的对 IFN-β 信号通路的抑制作用。这些数据表明，DNAJA3 通过降解 VP1 和恢复 IFN-β 信号通路来发挥重要的抗病毒作用，从而发挥抗病毒作用。
