Effect of human cytomegalovirus (HCMV) US27 on CXCR4 receptor internalization measured by fluorogen-activating protein (FAP) biosensors.
Effect of human cytomegalovirus (HCMV) US27 on CXCR4 receptor internalization measured by fluorogen-activating protein (FAP) biosensors.
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DOI：
10.1371/journal.pone.0172042
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发表时间：
2017
期刊：
影响因子：
3.7
通讯作者：
Spencer JV
中科院分区：
文献类型：
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作者：
Boeck JM;Spencer JV
人巨细胞病毒是一种分布广泛的病原体，属于疱疹病毒科。巨细胞病毒有一个很大的基因组，它编码许多对病毒复制不必要的基因，但却在操纵宿主免疫环境中发挥作用。其中之一是US27基因，它编码一种与G蛋白偶联受体(GPCRs)趋化因子受体家族同源的蛋白质。US27蛋白没有已知的趋化因子配体，但可以调节宿主受体CXCR4的信号活性。我们利用一种由荧光素激活蛋白(FAP)组成的新型生物传感器系统，研究了在US27存在下CXCR4信号增强的机制。FAP标记的CXCR4和US27用于研究受体内化和恢复动力学，结果表明，在CXCL12刺激下，US27的存在比单独使用CXCR4时观察到更多的CXCR4内化。当配体诱导的内吞速率较高时，CXCR4的稳态内化不受US27的影响。此外，US27经历了快速的内吞作用，其速率与CXCR4表达或CXCL12刺激无关。这些结果表明，US27增强CXCR4信号的一个机制是改变受体内化动力学，这最终可能通过增加HCMV感染细胞向高表达CXCL12的组织的转运来促进病毒传播。
Human cytomegalovirus (HCMV) is a widespread pathogen and a member of the Herpesviridae family. HCMV has a large genome that encodes many genes that are non-essential for virus replication but instead play roles in manipulation of the host immune environment. One of these is the US27 gene, which encodes a protein with homology to the chemokine receptor family of G protein-coupled receptors (GPCRs). The US27 protein has no known chemokine ligands but can modulate the signaling activity of host receptor CXCR4. We investigated the mechanism for enhanced CXCR4 signaling in the presence of US27 using a novel biosensor system comprised of fluorogen activating proteins (FAPs). FAP-tagged CXCR4 and US27 were used to explore receptor internalization and recovery dynamics, and the results demonstrate that significantly more CXCR4 internalization was observed in the presence of US27 compared to CXCR4 alone upon stimulation with CXCL12. While ligand-induced endocytosis rates were higher, steady state internalization of CXCR4 was not affected by US27. Additionally, US27 underwent rapid endocytosis at a rate that was independent of either CXCR4 expression or CXCL12 stimulation. These results demonstrate that one mechanism by which US27 can enhance CXCR4 signaling is to alter receptor internalization dynamics, which could ultimately have the effect of promoting virus dissemination by increasing trafficking of HCMV-infected cells to tissues where CXCL12 is highly expressed.