Microtubules, part of the cytoskeleton, are indispensable for intracellular movement, cell division, and maintaining cell shape and polarity. In addition, microtubules play an important role in viral infection. In this review, we summarize the role of the microtubules' network during polyomavirus infection. Polyomaviruses usurp microtubules and their motors to travel via early and late acidic endosomes to the endoplasmic reticulum. As shown for SV40, kinesin-1 and microtubules are engaged in the release of partially disassembled virus from the endoplasmic reticulum to the cytosol, and dynein apparently assists in the further disassembly of virions prior to their translocation to the cell nucleus-the place of their replication. Polyomavirus gene products affect the regulation of microtubule dynamics. Early T antigens destabilize microtubules and cause aberrant mitosis. The role of these activities in tumorigenesis has been documented. However, its importance for productive infection remains elusive. On the other hand, in the late phase of infection, the major capsid protein, VP1, of the mouse polyomavirus, counteracts T-antigen-induced destabilization. It physically binds microtubules and stabilizes them. The interaction results in the G2/M block of the cell cycle and prolonged S phase, which is apparently required for successful completion of the viral replication cycle.

• Klíčová slova
• T antigens, VP1 capsid protein, cell cycle block, dynein, kinesin, microtubules, molecular motors, polyomavirus, virus, virus trafficking,
• MeSH
• buněčné jádro virologie   MeSH
• cytosol virologie   MeSH
• endoplazmatické retikulum virologie   MeSH
• endozomy virologie   MeSH
• interakce hostitele a patogenu * MeSH
• lidé MeSH
• mikrotubuly fyziologie   virologie   MeSH
• myši MeSH
• Polyomavirus genetika   patogenita   MeSH
• replikace viru MeSH
• vazba proteinů MeSH
• virové plášťové proteiny genetika   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• přehledy MeSH
• Názvy látek
• virové plášťové proteiny MeSH
• VP1 protein, polyomavirus MeSH Prohlížeč

Mouse polyomavirus (PyV) virions enter cells by internalization into smooth monopinocytic vesicles, which fuse under the cell membrane with larger endosomes. Caveolin-1 was detected on monopinocytic vesicles carrying PyV particles in mouse fibroblasts and epithelial cells (33). Here, we show that PyV can be efficiently internalized by Jurkat cells, which do not express caveolin-1 and lack caveolae, and that overexpression of a caveolin-1 dominant-negative mutant in mouse epithelial cells does not prevent their productive infection. Strong colocalization of VP1 with early endosome antigen 1 (EEA1) and of EEA1 with caveolin-1 in mouse fibroblasts and epithelial cells suggests that the monopinocytic vesicles carrying the virus (and vesicles containing caveolin-1) fuse with EEA1-positive early endosomes. In contrast to SV40, PyV infection is dependent on the acidic pH of endosomes. Bafilomycin A1 abolished PyV infection, and an increase in endosomal pH by NH4Cl markedly reduced its efficiency when drugs were applied during virion transport towards the cell nucleus. The block of acidification resulted in the retention of a fraction of virions in early endosomes. To monitor further trafficking of PyV, we used fluorescent resonance energy transfer (FRET) to determine mutual localization of PyV VP1 with transferrin and Rab11 GTPase at a 2- to 10-nm resolution. Positive FRET between PyV VP1 and transferrin cargo and between PyV VP1 and Rab11 suggests that during later times postinfection (1.5 to 3 h), the virus meets up with transferrin in the Rab11-positive recycling endosome. These results point to a convergence of the virus and the cargo internalized by different pathways in common transitional compartments.

• MeSH
• buněčné linie MeSH
• časové faktory MeSH
• elektronová mikroskopie MeSH
• endozomy metabolismus   virologie   MeSH
• fúze membrán MeSH
• kaveolin 1 genetika   metabolismus   MeSH
• koncentrace vodíkových iontů MeSH
• myši MeSH
• Polyomavirus fyziologie   MeSH
• Rab proteiny vázající GTP metabolismus   MeSH
• rezonanční přenos fluorescenční energie MeSH
• transferin metabolismus   MeSH
• transport proteinů MeSH
• vazba proteinů MeSH
• virion metabolismus   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• kaveolin 1 MeSH
• Rab proteiny vázající GTP MeSH
• rab11 protein MeSH Prohlížeč
• transferin MeSH

Mouse polyomavirus enters host cells internalized, similar to simian virus 40 (SV40), in smooth monopinocytic vesicles, the movement of which is associated with transient actin disorganization. The major capsid protein (VP1) of the incoming polyomavirus accumulates on membranes around the cell nucleus. Here we show that unlike SV40, mouse polyomavirus infection is not substantially inhibited by brefeldin A, and colocalization of VP1 with beta-COP during early stages of polyomavirus infection in mouse fibroblasts was observed only rarely. Thus, these viruses obviously use different traffic routes from the plasma membrane toward the cell nucleus. At approximately 3 h postinfection, a part of VP1 colocalized with the endoplasmic reticulum marker BiP, and a subpopulation of virus was found in perinuclear areas associated with Rab11 GTPase and colocalized with transferrin, a marker of recycling endosomes. Earlier postinfection, a minor subpopulation of virions was found to be associated with Rab5, known to be connected with early endosomes, but the cell entry of virus was slower than that of transferrin or cholera toxin B-fragment. Neither Rab7, a marker of late endosomes, nor LAMP-2 lysosomal glycoprotein was found to colocalize with polyomavirus. In situ hybridization with polyomavirus genome-specific fluorescent probes clearly demonstrated that, regardless of the multiplicity of infection, only a few virions delivered their genomic DNA into the cell nucleus, while the majority of viral genomes (and VP1) moved back from the proximity of the nucleus to the cytosol, apparently for their degradation.

• MeSH
• biologický transport MeSH
• brefeldin A farmakologie   MeSH
• buněčné jádro virologie   MeSH
• chaperon endoplazmatického retikula BiP MeSH
• COP-vezikuly fyziologie   MeSH
• endozomy virologie   MeSH
• lyzozomy virologie   MeSH
• molekulární chaperony analýza   MeSH
• myši MeSH
• obalový protein analýza   MeSH
• Polyomavirus fyziologie   MeSH
• proteiny teplotního šoku * MeSH
• Rab proteiny vázající GTP analýza   MeSH
• Rab5 proteiny vázající GTP analýza   MeSH
• transportní proteiny analýza   MeSH
• virion fyziologie   MeSH
• virové plášťové proteiny analýza   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• brefeldin A MeSH
• chaperon endoplazmatického retikula BiP MeSH
• molekulární chaperony MeSH
• obalový protein MeSH
• proteiny teplotního šoku * MeSH
• Rab proteiny vázající GTP MeSH
• Rab5 proteiny vázající GTP MeSH
• Rab6 protein MeSH Prohlížeč
• transportní proteiny MeSH
• virové plášťové proteiny MeSH

Electron and confocal microscopy were used to observe the entry and the movement of polyomavirus virions and artificial virus-like particles (VP1 pseudocapsids) in mouse fibroblasts and epithelial cells. No visible differences in adsorption and internalization of virions and VP1 pseudocapsids ("empty" or containing DNA) were observed. Viral particles entered cells internalized in smooth monopinocytic vesicles, often in the proximity of larger, caveola-like invaginations. Both "empty" vesicles derived from caveolae and vesicles containing viral particles were stained with the anti-caveolin-1 antibody, and the two types of vesicles often fused in the cytoplasm. Colocalization of VP1 with caveolin-1 was observed during viral particle movement from the plasma membrane throughout the cytoplasm to the perinuclear area. Empty vesicles and vesicles with viral particles moved predominantly along microfilaments. Particle movement was accompanied by transient disorganization of actin stress fibers. Microfilaments decorated by the VP1 immunofluorescent signal could be seen as concentric curves, apparently along membrane structures that probably represent endoplasmic reticulum. Colocalization of VP1 with tubulin was mostly observed in areas close to the cell nuclei and on mitotic tubulin structures. By 3 h postinfection, a strong signal of the VP1 (but no viral particles) had accumulated in the proximity of nuclei, around the outer nuclear membrane. However, the vast majority of VP1 pseudocapsids did not enter the nuclei.

• MeSH
• adsorpce MeSH
• beta-cyklodextriny * MeSH
• biologický transport MeSH
• buněčné jádro metabolismus   virologie   MeSH
• buněčné linie MeSH
• cyklodextriny farmakologie   MeSH
• kapsida analýza   metabolismus   MeSH
• kaveolin 1 MeSH
• kaveoliny fyziologie   MeSH
• kaveoly fyziologie   MeSH
• myši MeSH
• Polyomavirus fyziologie   MeSH
• tubulin analýza   MeSH
• virion fyziologie   MeSH
• virové plášťové proteiny * MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• beta-cyklodextriny * MeSH
• Cav1 protein, mouse MeSH Prohlížeč
• cyklodextriny MeSH
• kaveolin 1 MeSH
• kaveoliny MeSH
• methyl-beta-cyclodextrin MeSH Prohlížeč
• tubulin MeSH
• virové plášťové proteiny * MeSH
• VP1 protein, polyomavirus MeSH Prohlížeč