Department of Microbiology & Immunology, Dalhousie University, Halifax, Canada.
Microbiology, Immunology & Infectious Diseases Department, University of Calgary, Calgary, Canada.
PLoS Pathog. 2023 Jan 12;19(1):e1011080. doi: 10.1371/journal.ppat.1011080. eCollection 2023 Jan.
Kaposi's sarcoma-associated herpesvirus (KSHV) causes the inflammatory and angiogenic endothelial cell neoplasm, Kaposi's sarcoma (KS). We previously demonstrated that the KSHV Kaposin B (KapB) protein promotes inflammation via the disassembly of cytoplasmic ribonucleoprotein granules called processing bodies (PBs). PBs modify gene expression by silencing or degrading labile messenger RNAs (mRNAs), including many transcripts that encode inflammatory or angiogenic proteins associated with KS disease. Although our work implicated PB disassembly as one of the causes of inflammation during KSHV infection, the precise mechanism used by KapB to elicit PB disassembly was unclear. Here we reveal a new connection between the degradative process of autophagy and PB disassembly. We show that both latent KSHV infection and KapB expression enhanced autophagic flux via phosphorylation of the autophagy regulatory protein, Beclin. KapB was necessary for this effect, as infection with a recombinant virus that does not express the KapB protein did not induce Beclin phosphorylation or autophagic flux. Moreover, we showed that PB disassembly mediated by KSHV or KapB, depended on autophagy genes and the selective autophagy receptor NDP52/CALCOCO2 and that the PB scaffolding protein, Pat1b, co-immunoprecipitated with NDP52. These studies reveal a new role for autophagy and the selective autophagy receptor NDP52 in promoting PB turnover and the concomitant synthesis of inflammatory molecules during KSHV infection.
卡波氏肉瘤相关疱疹病毒(KSHV)引起炎症和血管生成的内皮细胞肿瘤,卡波氏肉瘤(KS)。我们之前的研究表明,KSHV 的 Kaposin B(KapB)蛋白通过解聚细胞质核糖核蛋白颗粒(称为处理体(PBs))来促进炎症。PBs 通过沉默或降解不稳定的信使 RNA(mRNA)来修饰基因表达,包括许多编码与 KS 疾病相关的炎症或血管生成蛋白的转录本。虽然我们的工作表明 PB 解聚是 KSHV 感染期间炎症的原因之一,但 KapB 用于引发 PB 解聚的确切机制尚不清楚。在这里,我们揭示了自噬降解过程与 PB 解聚之间的新联系。我们表明,潜伏的 KSHV 感染和 KapB 表达都通过磷酸化自噬调节蛋白 Beclin 增强了自噬通量。KapB 是这种效应所必需的,因为感染不表达 KapB 蛋白的重组病毒不会诱导 Beclin 磷酸化或自噬通量。此外,我们表明由 KSHV 或 KapB 介导的 PB 解聚取决于自噬基因和选择性自噬受体 NDP52/CALCOCO2,并且 PB 支架蛋白 Pat1b 与 NDP52 共免疫沉淀。这些研究揭示了自噬和选择性自噬受体 NDP52 在促进 KSHV 感染期间 PB 周转和伴随炎症分子合成中的新作用。