Early Events in Integrin αvβ6-Mediated Cell Entry of Foot-and-Mouth Disease Virus

Abstract

We have shown that foot-and-mouth disease virus (FMDV) infection mediated by the integrin ␣v␤6 takes place through clathrin-dependent endocytosis but not caveolae or other endocytic pathways that depend on lipid rafts. Inhibition of clathrin-dependent endocytosis by sucrose treatment or expression of a dominantnegative version of AP180 inhibited virus entry and infection. Similarly, inhibition of endosomal acidification inhibited an early step in infection. Blocking endosomal acidification did not interfere with surface expression of ␣v␤6, virus binding to the cells, uptake of the virus into endosomes, or cytoplasmic virus replication, suggesting that the low pH within endosomes is a prerequisite for delivery of viral RNA into the cytosol. Using immunofluorescence confocal microscopy, FMDV colocalized with ␣v␤6 at the cell surface but not with the B subunit of cholera toxin, a marker for lipid rafts. At 37°C, virus was rapidly taken up into the cells and colocalized with markers for early and recycling endosomes but not with a marker for lysosomes, suggesting that infection occurs from within the early or recycling endosomal compartments. This conclusion was supported by the observation that FMDV infection is not inhibited by nocodazole, a reagent that inhibits vesicular trafficking between early and late endosomes (and hence trafficking to lysosomes). The integrin ␣v␤6 was also seen to accumulate in early and recycling endosomes on virus entry, suggesting that the integrin serves not only as an attachment receptor but also to deliver the virus to the acidic endosomes. These findings are all consistent with FMDV infection proceeding via clathrin-dependent endocytosis.

Murine norovirus-1 cell entry is mediated through a non-clathrin-, non-caveolae-, dynamin- and cholesterol-dependent pathway

“…To quantify MNV-1 infection, a modification of an ELISPOT assay was used (Berryman et al, 2005). Briefly, 3610 4 cells were seeded per well in 96-well tissueculture plates and grown overnight until approximately 80 % confluent.…”

“…RAW264.7 cells were treated with concanamycin A (or with DMSO as control) for 0.5 h prior to MNV-1 infection for 1 h. The cells were washed and incubated for a further 11 h, and infection quantified using an enzyme-linked immunospot (ELISPOT) assay ( Fig. 2a) (Berryman et al, 2005). Treatment of cells with concanamycin A had no effect on MNV-1 infection ( Fig.…”

HS1-Associated Protein X-1 Regulates Carcinoma Cell Migration and Invasion via Clathrin-Mediated Endocytosis of Integrin αvβ6

“…Clathrin-dependent endocytosis regulates cellular uptake of foot-and-mouth disease virus where a v h 6 is the known virus receptor (26). Thus, we examined if knockdown of CHC, essential for clathrin-coated pit formation, affected a v h 6 endocytosis in our lines.…”

Activated Epidermal Growth Factor Receptor Induces Integrin α2 Internalization via Caveolae/Raft-dependent Endocytic Pathway

“…EGF-stimulated Internalization of EGF Receptor and Integrin ␣2 through Distinct Pathways-Several mechanisms of integrin endocytosis have been reported (32)(33)(34). The trafficking of integrin ␣V␤6 and ␤1 has been reported to take place through an endosomal-mediated endocytic recycling pathway, but integrin ␣L␤2 was internalized and rapidly recycled upon chemoattractant stimulation via a clathrin-independent, cholesterolsensitive pathway.…”

“…Clathrin-dependent mechanisms have been described and integrins are involved in viral entry through clathrin-mediated pathways (33,46,47). ␣v␤5 is reportedly recruited to clathrincoated pits, and integrin ␤1 and L1 adhesion molecule complexes are internalized by clathrin-dependent endocytosis (46,48).…”