人磷脂加扰酶1(PLSCR1)在干扰素(IFN)治疗和病毒感染反应中强表达,它已被认为在IFN依赖性抗病毒反应中发挥重要作用。在这项研究中,我们发现PLSCR1基础表达高的OUMS-36T-3(36T-3)细胞中的人巨细胞病毒(HCMV)空斑形成水平明显低于PLSCR1基础表达低的人胚肺(HEL)细胞。此外,PLSCR1敲除(KO)36T-3细胞中HCMV斑块的形成和复制水平显着高于亲本36T-3细胞,并且与HEL细胞相当。此外,与PLSCR1-KO细胞相比,HCMV感染后,亲本36T-3细胞中HCMV主要立即早期(MIE)蛋白的表达被抑制和/或延迟。我们还显示PLSCR1表达降低了cAMP反应元件(CRE)结合蛋白(CREB)•HCMV立即早期蛋白2(IE2)和CREB结合蛋白(CBP)•IE2复合物的水平,它们被认为通过与CREB的相互作用在病毒早期启动子的IE2介导的反式激活中起重要作用,CBP,IE2有趣的是,PLSCR1表达抑制了CRE和HCMVMIE启动子调节的报告基因活性。这些观察显示,第一次,PLSCR1通过抑制病毒MIE和早期启动子的转录负调节HCMV复制,PLSCR1的表达可能有助于IFN介导的HCMV感染的抑制。重要性因为一些IFN-刺激基因(ISG)已被报道抑制HCMV复制,HCMV复制被认为是由IFN介导的宿主防御机制调节,但机制尚不清楚。PLSCR1表达是在对病毒感染和IFN治疗的反应中诱导的,和PLSCR1已被报道在IFN依赖性抗病毒反应中发挥重要作用。这里,我们证明,在PLSCR1-KO人成纤维细胞中,HCMV斑块形成和主要立即早期(MIE)基因表达显着增加。PLSCR1降低CREB·IE2和CBP·IE2复合物的水平,它们被认为通过与CREB的相互作用在HCMV复制中起重要作用,CBP,IE2此外,PLSCR1表达抑制HCMVMIE启动子的转录。我们的结果表明,PLSCR1在IFN介导的宿主防御系统中抑制HCMV复制中起重要作用。
Human phospholipid scramblase 1 (PLSCR1) is strongly expressed in response to interferon (IFN) treatment and viral infection, and it has been suggested to play an important role in IFN-dependent antiviral responses. In this study, we showed that the levels of human cytomegalovirus (HCMV) plaque formation in OUMS-36T-3 (36T-3) cells with high basal expression of PLSCR1 were significantly lower than those in human embryonic lung (HEL) cells with low basal expression of PLSCR1. In addition, the levels of HCMV plaque formation and replication in PLSCR1-knockout (KO) 36T-3 cells were significantly higher than those in parental 36T-3 cells and were comparable to those in HEL cells. Furthermore, compared to that in PLSCR1-KO cells, the expression of HCMV major immediate early (MIE) proteins was repressed and/or delayed in parental 36T-3 cells after HCMV infection. We also showed that PLSCR1 expression decreased the levels of the cAMP-responsive element (CRE)-binding protein (CREB)•HCMV immediate early protein 2 (IE2) and CREB-binding protein (CBP)•IE2 complexes, which have been suggested to play important roles in the IE2-mediated transactivation of the viral early promoter through interactions with CREB, CBP, and IE2. Interestingly, PLSCR1 expression repressed CRE- and HCMV MIE promoter-regulated reporter gene activities. These observations reveal, for the first time, that PLSCR1 negatively regulates HCMV replication by repressing the transcription from viral MIE and early promoters, and that PLSCR1 expression may contribute to the IFN-mediated suppression of HCMV infection. IMPORTANCE Because several IFN-stimulated genes (ISGs) have been reported to suppress HCMV replication, HCMV replication is thought to be regulated by an IFN-mediated host defense mechanism, but the mechanism remains unclear. PLSCR1 expression is induced in response to viral infection and IFN treatment, and PLSCR1 has been reported to play an important role in IFN-dependent antiviral responses. Here, we demonstrate that HCMV plaque formation and major immediate early (MIE) gene expression are significantly increased in PLSCR1-KO human fibroblast cells. PLSCR1 reduces levels of the CREB•IE2 and CBP•IE2 complexes, which have been suggested to play important roles in HCMV replication through its interactions with CREB, CBP, and IE2. In addition, PLSCR1 expression represses transcription from the HCMV MIE promoter. Our results indicate that PLSCR1 plays important roles in the suppression of HCMV replication in the IFN-mediated host defense system.