Significance of basolateral domain of polarized MDCK cells for Sendai virus-induced cell fusion.
Fusion (fusion from within) of polarized MDCK monolayer cells grown on porous membranes was examined after infection with Sendai viruses. Wild-type virus, that buds at the apical membrane domain, did not induce cell fusion even when the F glycoprotein expressed at the apical domain was activated with trypsin. On the other hand, a protease activation mutant, F1-R, with F protein in the activated form and that buds bipolarly at the apical and basolateral domains, caused syncytia formation in the absence of exogenous protease. Anti-Sendai virus antibodies added to the basolateral side, but not at the apical side, inhibited cell fusion induced by F1-R. In addition, T-9, a mutant with bipolar budding phenotype of F1-R but with an uncleavable F protein phenotype like wild-type virus, induced cell fusion exclusively when trypsin was added to the basolateral medium. By electron microscopy, cell-to-cell fusion was shown to occur at the lateral domain of the plasma membrane. These results indicate that in addition to proteolytic activation of the F protein, basolateral expression of Sendai virus envelope glycoproteins is required to induce cell fusion.
Tashiro
M
M
Department of Virology, Jichi Medical School, Tochigi, Japan.
Yamakawa
M
M
Tobita
K
K
Klenk
H D
HD
Seto
J T
JT
Rott
R
R
D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D002459:Cell Fusion; D002462:Cell Membrane; D016764:Cell Polarity; D002478:Cells, Cultured; D006461:Hemolysis; D010222:Parainfluenza Virus 1, Human / Q000502:physiology* / Q000648:ultrastructure; D014760:Viral Fusion Proteins / Q000737:chemistry / Q000502:physiology
D000914:Antibodies, Viral; D014760:Viral Fusion Proteins