Interaction of human papillomavirus type 16 particles with heparan sulfate and syndecan-1 molecules in the keratinocyte extracellular matrix plays an active role in infection

Abstract

Oncogenic human papillomaviruses (HPVs) attach predominantly to extracellular matrix (ECM) components during infection of cultured keratinocytes and in the rodent vaginal challenge model in vivo. However, the mechanism of virion transfer from the ECM to receptors that mediate entry into host cells has not been determined. In this work we strove to assess the role of heparan sulfate (HS) chains in HPV16 binding to the ECM and determine how HPV16 release from the ECM is regulated. We also assessed the extent to which capsids released from the ECM are infectious. We show that a large fraction of HPV16 particles binds to the ECM via HS chains, and that syndecan-1 (snd-1) molecules present in the ECM are involved in virus binding. Inhibiting the normal processing of snd-1 and HS molecules via matrix metalloproteinases and heparanase dramatically reduces virus release from the ECM, cellular uptake and infection. Conversely, exogenous heparinase activates each of these processes. We confirm that HPV16 released from the ECM is infectious in keratinocytes. Use of a specific inhibitor shows furin is not involved in HPV16 release from ECM attachment factors and corroborates other studies showing only the intracellular activity of furin is responsible for modulating HPV infectivity. These data suggest that our recently proposed model, describing the action of HS proteoglycan processing enzymes in releasing HPV16 from the cell surface in complex with the attachment factor snd-1, is also relevant to the release of HPV16 particles from the ECM to promote efficient infection of keratinocytes.

Novel 1, 3-N, O-Spiroheterocyclic compounds inhibit heparanase activity and enhance nedaplatin-induced cytotoxicity in cervical cancer cells

“…Inhibiting HPA activity dramatically reduces the release of the HPV16 virus from the extracellular matrix, as well as cellular uptake and infection. Conversely, exogenous HPA can activate this process [21]. HPV E6 and E7 proteins, two main carcinogenic proteins, can cause cellular transformation via their actions on multiple signal transduction pathways [22].…”

HPV entry into cells

“…Lastly, because the PsVs were lost from the BM under furin inhibition, data suggested that the conformational change that exposed the furin cleavage site on the capsid also resulted in a decreased binding affinity of the viral capsid for the HSPG [35]. An in vitro study found that furin cleavage was not required for PsVs to be transferred from the ECM to the cell surface [40]. It was concluded that HS-processing enzymes (heparanase and MMPs) are responsible for the release of ECM-bound virus since ECM binding of the virus is mediated via HS chains of shed syndecan-1 ectodomains [40].…”

“…An in vitro study found that furin cleavage was not required for PsVs to be transferred from the ECM to the cell surface [40]. It was concluded that HS-processing enzymes (heparanase and MMPs) are responsible for the release of ECM-bound virus since ECM binding of the virus is mediated via HS chains of shed syndecan-1 ectodomains [40]. Another in vitro study showed that PsVs with a mutated furin/PC cleavage site can bind to cells and be internalized [33].…”

Anatomy of a viral entry platform differentially functionalized by integrins α3 and α6

“…While integrin α6 mediates virus binding directly, other integrins could be involved indirectly by recruiting other well-established primary receptors such as heparan sulfate proteoglycans (HSPGs) [15][16][17][18] . Alternatively, integrins could mediate outside-in activation of signalling pathways 19 , which could link external virus binding to intracellular processes like endocytosis 20 .…”