Upregulation of ATF4-LAMP3 Axis by ORF45 Facilitates Lytic Replication of Kaposi's Sarcoma-Associated Herpesvirus
Upregulation of ATF4-LAMP3 Axis by ORF45 Facilitates Lytic Replication of Kaposi's Sarcoma-Associated Herpesvirus
复制标题
ORF45 上调 ATF4-LAMP3 轴促进卡波西肉瘤相关疱疹病毒的裂解复制
DOI：
10.1128/jvi.01456-22
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发表时间：
2022-11-15
影响因子：
5.4
通讯作者：
Kuang，Ersheng
中科院分区：
文献类型：
--
作者：
Sun，Qinqin;Wang，Fan;Kuang，Ersheng
卡波济肉瘤相关疱疹病毒（Kaposi ′ ssarcoma-associated herpesvirus，KSHV）是一种γ-致癌疱疹病毒，裂解性和潜伏性感染在其致病和致瘤特性中起重要作用。多种细胞途径和不同的介质被病毒蛋白质劫持，并用于支持KSHV裂解复制。在先前的研究中，我们发现KSHV ORF 45通过诱导持续的p90核糖体S6激酶（RSK）激活及其底物c-Fos和eIF 4 B的磷酸化来促进KSHV的转录和翻译。然而，裂解复制所需的细胞介质仍然在很大程度上未知。在这里，我们揭示了ORF 45激活eIF 2 α磷酸化和ATF 4翻译，然后在KSHV裂解复制过程中以ATF 4依赖的方式上调溶酶体相关膜蛋白3（LAMP 3）的表达。因此，LAMP 3促进Akt和ERK活化，然后促进裂解基因表达和病毒体产生。此外，ATF 4通过LAMP 3增强裂解复制，并且LAMP 3以不依赖于ATF 4的方式起作用。我们的研究结果表明，ATF 4-LAMP 3轴上调ORF 45通过ER应激激活过程中的KSHV裂解的生命周期，反过来，有利于最佳的裂解replication.IMPORTANCEThe裂解复制卡波西肉瘤相关疱疹病毒（KSHV）重新编程细胞的转录和翻译，产生病毒蛋白和病毒粒子。在这里，我们表明，ER应激的中介ATF 4和下游基因LAMP 3的表达上调ORF 45在裂解复制。因此，增加的LAMP 3表达激活Akt和ERK并促进裂解性复制。尽管几种UPR转录因子能够促进KSHV裂解复制，但ATF 4对裂解复制的前病毒作用通过LAMP 3沉默而减弱，而LAMP 3的作用不直接需要ATF 4表达，表明LAMP 3主要在ATF 4和ER应激下游对KSHV裂解复制发挥作用。综上所述，我们的研究结果表明，ORF 45上调的ATF 4-LAMP 3轴在KSHV裂解复制中起重要作用。
Kaposi’s sarcoma-associated herpesvirus (KSHV) is a γ-oncogenic herpesvirus, and both lytic and latent infections play important roles in its pathogenesis and tumorigenic properties. Multiple cellular pathways and diverse mediators are hijacked by viral proteins and are used to support KSHV lytic replication. In previous studies, we revealed that KSHV ORF45 promoted KSHV transcription and translation by inducing sustained p90 ribosomal S6 kinase (RSK) activation and the phosphorylation of its substrates c-Fos and eIF4B. However, the cellular mediators required for lytic replication remain largely unknown. Here, we reveal that ORF45 activates eIF2α phosphorylation and ATF4 translation and then upregulates the expression of lysosome-associated membrane protein 3 (LAMP3) in an ATF4-dependent manner during KSHV lytic replication. Consequently, LAMP3 promotes Akt and ERK activation and then facilitates lytic gene expression and virion production. Furthermore, ATF4 enhances lytic replication through LAMP3, and LAMP3 acts in an ATF4-independent manner. Our findings suggest that the ATF4-LAMP3 axis is upregulated by ORF45 through ER stress activation during the KSHV lytic life cycle and, in turn, facilitates optimal lytic replication.IMPORTANCEThe lytic replication of Kaposi’s sarcoma-associated herpesvirus (KSHV) reprograms cellular transcription and translation to generate viral proteins and virion particles. Here, we show that the mediator of ER stress ATF4 and the expression of the downstream gene LAMP3 are upregulated by ORF45 during lytic replication. Consequently, increased LAMP3 expression activates Akt and ERK and promotes lytic replication. Although several UPR transcription factors are able to promote KSHV lytic replication, the proviral effect of ATF4 on lytic replication is attenuated by LAMP3 silencing, whereas the effect of LAMP3 does not directly require ATF4 expression, indicating that LAMP3 primarily exerts effects on KSHV lytic replication downstream of ATF4 and ER stress. Taken together, our findings suggest that the ORF45-upregulated ATF4-LAMP3 axis plays an essential role in KSHV lytic replication.