Nucleocytoplasmic traffic disorder induced by cardioviruses.
Some picornaviruses, for example, poliovirus, increase bidirectional permeability of the nuclear envelope and suppress active nucleocytoplasmic transport. These activities require the viral protease 2A(pro). Here, we studied nucleocytoplasmic traffic in cells infected with encephalomyocarditis virus (EMCV; a cardiovirus), which lacks the poliovirus 2A(pro)-related protein. EMCV similarly enhanced bidirectional nucleocytoplasmic traffic. By using the fluorescent "Timer" protein, which contains a nuclear localization signal, we showed that the cytoplasmic accumulation of nuclear proteins in infected cells was largely due to the nuclear efflux of "old" proteins rather than impaired active nuclear import of newly synthesized molecules. The nuclear envelope of digitonin-treated EMCV-infected cells permitted rapid efflux of a nuclear marker protein. Inhibitors of poliovirus 2A(pro) did not prevent the EMCV-induced efflux. Extracts from EMCV-infected cells and products of in vitro translation of viral RNAs contained an activity increasing permeability of the nuclear envelope of uninfected cells. This activity depended on the expression of the viral leader protein. Mutations disrupting the zinc finger motif of this protein abolished its efflux-inducing ability. Inactivation of the L protein phosphorylation site (Thr47-->Ala) resulted in a delayed efflux, while a phosphorylation-mimicking (Thr47-->Asp) replacement did not significantly impair the efflux-inducing ability. Such activity of extracts from EMCV-infected cells was suppressed by the protein kinase inhibitor staurosporine. As evidenced by electron microscopy, cardiovirus infection resulted in alteration of the nuclear pores, but it did not trigger degradation of the nucleoporins known to be degraded in the poliovirus-infected cells. Thus, two groups of picornaviruses, enteroviruses and cardioviruses, similarly alter the nucleocytoplasmic traffic but achieve this by strikingly different mechanisms.
Lidsky
Peter V
PV
M. P. Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical Sciences, Moscow Region, Russia.
Hato
Stanleyson
S
Bardina
Maryana V
MV
Aminev
Alexei G
AG
Palmenberg
Ann C
AC
Sheval
Eugene V
EV
Polyakov
Vladimir Y
VY
van Kuppeveld
Frank J M
FJ
Agol
Vadim I
VI
D021581:Active Transport, Cell Nucleus; D000818:Animals; D002460:Cell Line; D004686:Encephalomyocarditis virus / Q000472:pathogenicity*; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D009685:Nuclear Envelope; D019913:Nuclear Localization Signals / Q000378:metabolism; D022022:Nuclear Pore / Q000473:pathology; D009687:Nuclear Proteins / Q000378:metabolism; D010447:Peptide Hydrolases / Q000378:metabolism; D014764:Viral Proteins / Q000378:metabolism
D008164:Luminescent Proteins; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D014764:Viral Proteins; D010447:Peptide Hydrolases