Wu Jing, Zhao Yuxue, Chen Qiaoqiao, Chen Yiwen, Gu Jiaqi, Mao Lingxiang
Department of Laboratory Medicine, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, Jiangsu, China.
Microbiol Spectr. 2023 Feb 15;11(2):e0344622. doi: 10.1128/spectrum.03446-22.
Exosomes are small membrane-bound vesicles which are intraluminal vesicles (ILVs) secreted to the extracellular space after multivesicular bodies (MVBs) fuse with the plasma membrane. Although it is known that exosomes play a multitude of roles during viral infection, the mechanism that regulates their secretion during viral infection is unknown. Here, we found that enterovirus A71 (EV-A71) infection increased exosome secretion both and . Importantly, the expression of nonstructural protein 3A was sufficient to promote exosome secretion, while a mutation affecting the amino acid 18 position abrogated this effect, without changing the size of exosomes or . Transmission electron microscopy (TEM) analysis revealed that 3A decreases the number of MVBs and ILVs and , which suggested 3A may boost the fusion between MVBs and the plasma membrane. Furthermore, we demonstrated that an interaction between 3A and the small GTPase protein, Rab27a, protected Rab27a from ubiquitination, resulted in increasing exosome release. Data indicated a novel mechanism by which EV-A71 3A modifies exosome secretion during viral infection. Research has shown that viral infection impacts exosome secretion, but its regulation mechanisms remain poorly understood. Nonstructural protein 3A of EV-A71 interacts with many host factors and is involved in the remodeling of cellular membranes. In this investigation, we applied exogenous expression of 3A protein for exploring its regulation on exosome secretion and utilized immunoprecipitation combined with proteomics approaches to identify 3A-interacting factors. Our results demonstrate that 3A protein upregulates the release of the exosomes and that the 3A mutant strain of EV-A71 induce less exosome release compared with the EV-A71 wild type. Viral 3A protein interacts with the host factor Rab27a to prevent it from being ubiquitinated, which in turn improves exosome secretion both and . EV-A71 3A protein is a novel viral factor in the control of exosome production.
外泌体是小的膜结合囊泡，是多泡体（MVBs）与质膜融合后分泌到细胞外空间的腔内囊泡（ILVs）。虽然已知外泌体在病毒感染期间发挥多种作用，但病毒感染期间调节其分泌的机制尚不清楚。在这里，我们发现肠道病毒A71（EV-A71）感染增加了外泌体的分泌。重要的是，非结构蛋白3A的表达足以促进外泌体分泌，而影响第18位氨基酸的突变消除了这种作用，且未改变外泌体的大小。透射电子显微镜（TEM）分析显示，3A减少了MVBs和ILVs的数量，这表明3A可能促进MVBs与质膜之间的融合。此外，我们证明3A与小GTPase蛋白Rab27a之间的相互作用保护Rab27a不被泛素化，从而增加外泌体释放。数据表明了一种新的机制，通过该机制EV-A71 3A在病毒感染期间改变外泌体分泌。研究表明病毒感染会影响外泌体分泌，但其调节机制仍知之甚少。EV-A71的非结构蛋白3A与许多宿主因子相互作用，并参与细胞膜的重塑。在本研究中，我们应用3A蛋白的外源性表达来探索其对外泌体分泌的调节作用，并利用免疫沉淀结合蛋白质组学方法来鉴定与3A相互作用的因子。我们的结果表明，3A蛋白上调外泌体的释放，并且与EV-A71野生型相比，EV-A71的3A突变株诱导的外泌体释放较少。病毒3A蛋白与宿主因子Rab27a相互作用以防止其被泛素化，这反过来又增加了外泌体的分泌。EV-A71 3A蛋白是控制外泌体产生的一种新型病毒因子。
