肠病毒是单链的,导致内质网(ER)应激的阳性RNA病毒诱导或调节下游信号通路,称为未折叠蛋白反应(UPR)。然而,与病毒发病机制相关的UPR中涉及的病毒和宿主因素仍不清楚.在本研究中,我们旨在鉴定肠道病毒诱导的UPR的主要调节因子,并阐明其潜在的分子机制.我们表明,宿主高尔基体特异性brefeldinA抗性鸟嘌呤核苷酸交换因子1(GBF1),支持肠病毒复制,是由肠道病毒感染引起的UPR的主要调节剂。此外,我们发现,严重的UPR是由人类致病性肠道病毒编码的3A蛋白的表达诱导的,如肠道病毒A71,柯萨奇病毒B3,脊髓灰质炎病毒,和肠道病毒D68.3A蛋白的N端保守残基与GBF1相互作用,并通过GBF1隔离抑制ADP-核糖基化因子1(ARF1)的激活来诱导UPR。在感染肠病毒的细胞中观察到ER的重塑和扩增以及ER驻留蛋白的积累。最后,图3A通过激活UPR的蛋白激酶RNA样内质网激酶(PERK)/C/EBP同源蛋白(CHOP)途径诱导感染肠道病毒的细胞凋亡。PERK的药物抑制抑制由肠道病毒感染引起的细胞死亡,提示UPR通路是治疗由肠道病毒感染引起的疾病的治疗靶点。重要性由几种正链RNA病毒引起的感染导致宿主细胞内内质网稳态失调。内质网稳态的破坏和损害的潜在机制及其在肠道病毒感染的发病机理中的意义仍不清楚。我们的发现表明,人类致病性肠道病毒中编码的3A蛋白通过与UPR的主要调节剂GBF1相互作用来破坏ER稳态。肠道病毒介导的感染使ER进入致病状态,积累ER驻留蛋白的地方。此外,在这种情况下,由未解决的ER稳态失衡诱导的PERK/CHOP信号通路基本上驱动细胞凋亡。因此,阐明病毒诱导内质网稳态破坏的潜在机制可能是缓解肠道病毒发病机制的潜在靶点.
Enteroviruses are single-stranded, positive-sense RNA viruses causing endoplasmic reticulum (ER) stress to induce or modulate downstream signaling pathways known as the unfolded protein responses (UPR). However, viral and host factors involved in the UPR related to viral pathogenesis remain unclear. In the present study, we aimed to identify the major regulator of
enterovirus-induced UPR and elucidate the underlying molecular mechanisms. We showed that host Golgi-specific brefeldin A-resistant guanine nucleotide exchange factor 1 (GBF1), which supports enteroviruses replication, was a major regulator of the UPR caused by infection with enteroviruses. In addition, we found that severe UPR was induced by the expression of 3A proteins encoded in human pathogenic enteroviruses, such as
enterovirus A71, coxsackievirus B3, poliovirus, and
enterovirus D68. The N-terminal-conserved residues of 3A protein interact with the GBF1 and induce UPR through inhibition of ADP-ribosylation factor 1 (ARF1) activation via GBF1 sequestration. Remodeling and expansion of ER and accumulation of ER-resident proteins were observed in cells infected with enteroviruses. Finally, 3A induced apoptosis in cells infected with enteroviruses via activation of the protein kinase RNA-like endoplasmic reticulum kinase (PERK)/C/EBP homologous protein (CHOP) pathway of UPR. Pharmaceutical inhibition of PERK suppressed the cell death caused by infection with enteroviruses, suggesting the UPR pathway is a therapeutic target for treating diseases caused by infection with enteroviruses.IMPORTANCEInfection caused by several plus-stranded RNA viruses leads to dysregulated ER homeostasis in the host cells. The mechanisms underlying the disruption and impairment of ER homeostasis and its significance in pathogenesis upon enteroviral infection remain unclear. Our findings suggested that the 3A protein encoded in human pathogenic enteroviruses disrupts ER homeostasis by interacting with GBF1, a major regulator of UPR.
Enterovirus-mediated infections drive ER into pathogenic conditions, where ER-resident proteins are accumulated. Furthermore, in such scenarios, the PERK/CHOP signaling pathway induced by an unresolved imbalance of ER homeostasis essentially drives apoptosis. Therefore, elucidating the mechanisms underlying the virus-induced disruption of ER homeostasis might be a potential target to mitigate the pathogenesis of enteroviruses.