The CD63-Syntenin-1 Complex Controls Post-Endocytic Trafficking of Oncogenic Human Papillomaviruses

Abstract

Human papillomaviruses enter host cells via a clathrin-independent endocytic pathway involving tetraspanin proteins. However, post-endocytic trafficking required for virus capsid disassembly remains unclear. Here we demonstrate that the early trafficking pathway of internalised HPV particles involves tetraspanin CD63, syntenin-1 and ESCRT-associated adaptor protein ALIX. Following internalisation, viral particles are found in CD63-positive endosomes recruiting syntenin-1, a CD63-interacting adaptor protein. Electron microscopy and immunofluorescence experiments indicate that the CD63-syntenin-1 complex controls delivery of internalised viral particles to multivesicular endosomes. Accordingly, infectivity of high-risk HPV types 16, 18 and 31 as well as disassembly and post-uncoating processing of viral particles was markedly suppressed in CD63 or syntenin-1 depleted cells. Our analyses also present the syntenin-1 interacting protein ALIX as critical for HPV infection and CD63-syntenin-1-ALIX complex formation as a prerequisite for intracellular transport enabling viral capsid disassembly. Thus, our results identify the CD63-syntenin-1-ALIX complex as a key regulatory component in post-endocytic HPV trafficking.

HIV internalization into oral and genital epithelial cells by endocytosis and macropinocytosis leads to viral sequestration in the vesicles

“…HSPG interaction with many viruses, including retroviruses and papillomaviruses, facilitates viral entry by using clathrin- and caveolin/lipid raft-dependent and independent pathways and macropinocytosis (Bobardt et al, 2007; Christianson and Belting, 2014; Connell and Lortat-Jacob, 2013; Grassel et al, 2016; Jones et al, 2005; Letian and Tianyu, 2010; Payne et al, 2007; Schelhaas et al, 2012). Human papillomavirus (HPV) types 16, 18 and 31 interaction with syndecan-1/HSPG and tetraspanin CD63 facilitate delivery of virus into MVB (Grassel et al, 2016). Post-endocytic interaction of the HPV/HSPG/CD63 complex with ESCRT protein Alix is critical for delivery of internalized virions to MVB (Grassel et al, 2016).…”

“…Human papillomavirus (HPV) types 16, 18 and 31 interaction with syndecan-1/HSPG and tetraspanin CD63 facilitate delivery of virus into MVB (Grassel et al, 2016). Post-endocytic interaction of the HPV/HSPG/CD63 complex with ESCRT protein Alix is critical for delivery of internalized virions to MVB (Grassel et al, 2016). HIV-1 interaction with HSPG is important for viral attachment, internalization and sequestration in tonsil, cervical and foreskin epithelial cells, suggesting that HSPG may play a major role in virus sequestration in oral and genital mucosal epithelium.…”

Cruising the cellular highways: How human papillomavirus travels from the surface to the nucleus

“…Early HPV-harboring endocytic vesicle trafficking requires the tetraspanin CD63, syntenin-1, and ESCRT-associated ALIX and results in delivery of HPV particles to multivesicular endosomes (Grassel et al, 2016; Schelhaas et al, 2012; Spoden et al, 2008). These recent findings strengthen the argument for TEMs serving as entry platforms.…”

Human Papillomavirus Major Capsid Protein L1 Remains Associated with the Incoming Viral Genome throughout the Entry Process

“…In addition, a fraction of L1 protein is cleaved by kallekrein-8 on the cell surface (15). Following these conformational changes, the virion is reported to associate with a number of non-HSPG secondary receptors, including integrins, tetraspanins, growth factor receptors, and annexin A2, that serve as a platform for internalization (16)(17)(18)(19)(20)(21)(22)(23)(24). The virion is internalized via the endocytic route and is trafficked to the endosome whereupon low pH triggers disassembly of the capsid.…”