Center for Membrane and Cell Physiology, University of Virginia, Charlottesville, Virginia, USA.
Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia, USA.
Traffic. 2022 Apr;23(4):221-234. doi: 10.1111/tra.12836. Epub 2022 Feb 21.
Most enveloped viruses infect cells by binding receptors at the cell surface and undergo trafficking through the endocytic pathway to a compartment with the requisite conditions to trigger fusion with a host endosomal membrane. Broad categories of compartments in the endocytic pathway include early and late endosomes, which can be further categorized into subpopulations with differing rates of maturation and motility characteristics. Endocytic compartments have varying protein and lipid components, luminal ionic conditions and pH that provide uniquely hospitable environments for specific viruses to fuse. In order to characterize compartments that permit fusion, we studied the trafficking and fusion of viral particles pseudotyped with the vesicular stomatitis virus glycoprotein (VSV-G) on their surface and equipped with a novel pH sensor and a fluorescent content marker to measure pH, motion and fusion at the single particle level in live cells. We found that the VSV-G particles fuse predominantly from more acidic and more motile endosomes, and that a significant fraction of particles is trafficked to more static and less acidic endosomes that do not support their fusion. Moreover, the fusion-supporting endosomes undergo directed motion.
大多数包膜病毒通过与细胞表面的受体结合感染细胞，并通过内吞途径运输到具有触发与宿主内吞体膜融合所需条件的隔室。内吞途径中的隔室大致可分为早期和晚期内体，它们可以进一步细分为具有不同成熟速度和运动特征的亚群。内吞隔室具有不同的蛋白质和脂质成分、腔内离子条件和 pH 值，为特定病毒的融合提供了独特的有利环境。为了表征允许融合的隔室，我们研究了表面带有水疱性口炎病毒糖蛋白 (VSV-G) 的病毒颗粒的运输和融合，这些颗粒配备了新型 pH 传感器和荧光内容标记物，可在活细胞中测量单个颗粒水平的 pH 值、运动和融合。我们发现，VSV-G 颗粒主要从酸性更强且更具运动性的内体中融合，并且相当一部分颗粒被运输到不支持其融合的更静态且酸性较弱的内体中。此外，支持融合的内体发生定向运动。
