BACKGROUND: We investigated the targeting of microtubules (MT) and F-actin cytoskeleton (AC) of the human pathogenic yeast Cryptococcus neoformans with agents for cancer therapy, in order to examine whether this yeast cytoskeleton could become a new antifungal target for the inhibition of cell division. METHODS: Cells treated with 10 cytoskeleton inhibitors in yeast extract peptone dextrose medium were investigated by phase-contrast and fluorescence microscopy, and growth inhibition was estimated by cell counts using a Bürker chamber and measuring absorbance for 6 days. RESULTS: Docetaxel, paclitaxel, vinblastine sulfate salt, cytochalasin D and chlorpropham [isopropyl N-(3-chlorophenyl) carbamate] did not inhibit proliferation. The MT inhibitors methyl benzimidazole-2-ylcarbamate (BCM), nocodazole, thiabendazole (TBZ) and vincristine (VINC) disrupted MT and inhibited mitoses, but anucleated buds emerged on cells that increased in size, vacuolated and seemed to die after 2 days. The response of the cells to the presence of the actin inhibitor latrunculin A (LA) included the disappearance of actin patches, actin cables and actin rings; this arrested budding and cell division. However, in 3-4 days, resistant budding cells appeared in all 5 inhibitors. Disruption of the MT and AC and inhibition of cell division and budding persisted only when the MT and AC inhibitors were combined, i.e. VINC + LA, BCM + LA or TBZ + LA. CONCLUSION: The MT and AC of C. neoformans are new antifungal targets for the persistent inhibition of cell division by combined F-actin and MT inhibitors.
- MeSH
- aktiny antagonisté a inhibitory MeSH
- antifungální látky farmakologie MeSH
- bicyklické sloučeniny heterocyklické farmakologie MeSH
- buněčné dělení účinky léků MeSH
- Cryptococcus neoformans účinky léků MeSH
- fluorescenční mikroskopie MeSH
- lidé MeSH
- mikrofilamenta účinky léků MeSH
- mikrotubuly účinky léků MeSH
- protinádorové látky farmakologie MeSH
- racionální návrh léčiv MeSH
- thiazolidiny farmakologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Our basic cell biology research was aimed at investigating the effect on eukaryotic cells of the sudden loss of the F-actin cytoskeleton. Cells treated with latrunculin A (LA) in yeast extract peptone dextrose (YEPD) medium were examined using phase-contrast and fluorescent microscopy, freeze-substitution, transmission and scanning electron microscopy, counted using a Bürker chamber and their absorbance measured. The cells responded to the presence of LA, an F-actin inhibitor, with the disappearance of actin patches, actin cables and actin rings. This resulted in the formation of larger spherical cells with irregular morphology in the cell walls and ultrastructural disorder of the cell organelles and secretory vesicles. Instead of buds, LA-inhibited cells formed only 'table-mountain-like' wide flattened swellings without apical growth with a thinner glucan cell-wall layer containing β-1,3-glucan microfibrils. The LA-inhibited cells lysed. Actin cables and patches were required for bud formation and bud growth. In addition, actin patches were required for the formation of β-1,3-glucan microfibrils in the bud cell wall. LA has fungistatic, fungicidal and fungilytic effects on the budding yeast Saccharomyces cerevisiae.
- MeSH
- aktiny antagonisté a inhibitory MeSH
- antifungální látky farmakologie MeSH
- bicyklické sloučeniny heterocyklické farmakologie MeSH
- mikrobiální viabilita účinky léků MeSH
- mikroskopie MeSH
- počet mikrobiálních kolonií MeSH
- Saccharomyces cerevisiae cytologie účinky léků fyziologie MeSH
- Saccharomycetales cytologie účinky léků fyziologie MeSH
- thiazolidiny farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
BACKGROUND: This basic research aimed to investigate the effects of the actin inhibitor latrunculin A (LA) on the human pathogen Cryptococcus neoformans, by freeze-substitution (FS) and electron microscopy (EM), to determine whether the actin cytoskeleton can become a new antifungal target for inhibition of cell division. METHODS: Cells treated with LA for 20 h in yeast-extract peptone dextrose medium were investigated by phase-contrast and fluorescent microscopy, FS and transmission EM, counted in a Bürker chamber and the absorbance was then measured. RESULTS: The disappearance of actin patches, actin cables and actin rings demonstrated the response of the cells of C. neoformans to the presence of the actin inhibitor LA. The removal of actin cables and patches arrested proliferation and led to the production of cells that had ultrastructural disorder, irregular morphology of the mitochondria and thick aberrant cell walls. Budding cells lysed in the buds and septa. CONCLUSION: LA exerts fungistatic, fungicidal and fungilytic effects on the human pathogenic yeast C. neoformans.
- MeSH
- aktiny antagonisté a inhibitory MeSH
- antifungální látky farmakologie MeSH
- bicyklické sloučeniny heterocyklické farmakologie MeSH
- buněčná stěna účinky léků metabolismus MeSH
- buněčné dělení účinky léků MeSH
- Cryptococcus neoformans účinky léků metabolismus MeSH
- elektronová mikroskopie metody MeSH
- fluorescenční mikroskopie metody MeSH
- kryptokokóza farmakoterapie metabolismus mikrobiologie MeSH
- lidé MeSH
- mikrofilamenta účinky léků metabolismus MeSH
- proliferace buněk účinky léků MeSH
- thiazolidiny farmakologie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The F-actin cytoskeleton of Cryptococcus neoformans is known to comprise actin cables, cortical patches and cytokinetic ring. Here, we describe a new F-actin structure in fungi, a perinuclear F-actin collar ring around the cell nucleus, by fluorescent microscopic imaging of rhodamine phalloidin-stained F-actin. Perinuclear F-actin rings form in Cryptococcus neoformans treated with the microtubule inhibitor Nocodazole or with the drug solvent dimethyl sulfoxide (DMSO) or grown in yeast extract peptone dextrose (YEPD) medium, but they are absent in cells treated with Latrunculin A. Perinuclear F-actin rings may function as 'funicular cabin' for the cell nucleus, and actin cables as intracellular 'funicular' suspending nucleus in the central position in the cell and moving nucleus along the polarity axis along actin cables.
- MeSH
- aktiny analýza MeSH
- bicyklické sloučeniny heterocyklické farmakologie MeSH
- buněčné jádro ultrastruktura MeSH
- Cryptococcus neoformans účinky léků fyziologie ultrastruktura MeSH
- dimethylsulfoxid farmakologie MeSH
- elektronová mikroskopie MeSH
- faloidin analogy a deriváty MeSH
- fluorescenční mikroskopie MeSH
- mikrofilamenta ultrastruktura MeSH
- mikrotubuly účinky léků MeSH
- modulátory tubulinu farmakologie MeSH
- mořské toxiny farmakologie MeSH
- nokodazol farmakologie MeSH
- rhodaminy MeSH
- scavengery volných radikálů farmakologie MeSH
- thiazolidiny farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Polysaccharides account for more than 90% of the content of fungal cell walls, but the mechanism underlying the formation of the architecture of the cell walls, which consist of microfibrils embedded in an amorphous wall matrix, remains unknown. We used electron microscopy to investigate ten different fungal cell-wall polysaccharides to determine whether they could self-assemble into the fibrillar or amorphous component of fungal cell walls in a test tube without enzymes. The ultrastructures formed by precipitating β-1,3-glucan and β-1,6-glucan are different depending on the existence of branching in the molecule. Linear β-1,3-glucan and linear β-1,6-glucan precipitate into a fibrillar ultrastructure. Branched β-1,6-glucan, mannan and glycogen precipitates are amorphous. Branched β-1,3-glucan forms a fibrillar plus amorphous ultrastructure. Self-assembly among combinations of different linear and branched cell-wall polysaccharides results in an ultrastructure that resembles that of a yeast cell wall, which suggests that self-assembly of polysaccharides may participate in the development of the three-dimensional architecture of the yeast cell wall.
- MeSH
- beta-glukany chemie metabolismus MeSH
- buněčná stěna ultrastruktura MeSH
- elektronová mikroskopie MeSH
- fungální polysacharidy biosyntéza metabolismus MeSH
- mannany chemie metabolismus MeSH
- mikrofibrily metabolismus MeSH
- Saccharomyces cerevisiae metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
The yeast strains VKM Y-2977 and VKM Y-2978, derived from the isolate Pa-202, were examined for their physiological properties and mycocin sensitivities and studied by light, phase-contrast, fluorescence, transmission and scanning electron microscopy. The cells of the first strain produced long stalk-like conidiophores, whereas the cells of the second one had the appearance of a typical budding yeast under the light microscope. Transmission and scanning electron microscopy showed the formation of stalk-like conidiophores and long necks in VKM Y-2977, similar in appearance to Fellomyces fuzhouensis. The actin cytoskeleton, microtubules and nuclei were similar as well, but due to presence of a capsule, they were not clearly visible. The second isolate, VKM Y-2978, had very short stalk-like conidiophores, and the neck, microtubules and actin cables were shorter as well. The actin patches, actin cables, and microtubules were similar in VKM Y-2977 and VKM Y-2978 and not clearly visible. The physiological characteristics and mycocin sensitivity patterns, together with the microscopic structures and ultrastructures, led us to conclude that both strains belong to Fellomyces penicillatus, even though they differ in the lengths of their stalk-like conidiophores and necks.
- MeSH
- aktiny ultrastruktura MeSH
- antifungální látky farmakologie MeSH
- Basidiomycota klasifikace účinky léků růst a vývoj ultrastruktura MeSH
- buněčné jádro ultrastruktura MeSH
- cytoplazma ultrastruktura MeSH
- mikroskopie MeSH
- mikrotubuly ultrastruktura MeSH
- spory hub účinky léků růst a vývoj ultrastruktura MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
The unique long-neck yeast Fellomyces fuzhouensis has F-actin cables and cortical patches. Here, we describe a new F-actin structure present in fungi, a perinuclear F-actin collar ring around the cell nucleus. This F-actin structure can be visualized by fluorescent microscopic imaging of rhodamine-phalloidin-stained F-actin in cells treated with the mitotic drug isopropyl N-(3-chlorophenyl) carbamate or the microtubule inhibitor thiabendazol or when cells were grown in cut dried radish medium or yeast extract pepton dextrose (YEPD) medium. In contrast, these structures were absent in cells treated with Latrunculin A. The hypothetical functions of the F-actin ring are discussed.
- MeSH
- aktiny metabolismus MeSH
- Basidiomycota účinky léků růst a vývoj metabolismus ultrastruktura MeSH
- bicyklické sloučeniny heterocyklické farmakologie MeSH
- buněčné jádro metabolismus MeSH
- fluorescenční mikroskopie MeSH
- mikrofilamenta metabolismus ultrastruktura MeSH
- thiazolidiny farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Temperature-sensitive actin mutant of Saccharomyces cerevisiae act1-1 was studied at a permissive temperature of 23°C by light, fluorescent and electron microscopy to elucidate the roles of actin cytoskeleton in the cycling eukaryotic cells. Mutant cells that grew slowly at the permissive temperature showed aberrations in the cytoskeleton and cell cycle. Mutant cells contained aberrant 'faint actin cables,' that failed in directing of mitochondria, vacuoles and secretory vesicles to the bud and the stray vesicles delivered their content to the mother wall instead of the bud. Bud growth was delayed. Spindle pole bodies and cytoplasmic microtubules did not direct to the bud, and nucleus failed to migrate to the bud. Repeated nuclear divisions produced multinucleated cells, indicating continued cycling of actin mutant cells that failed in the morphogenetic checkpoint, the spindle position checkpoint and cytokinesis. Thus, a single actin mutation appears to indicate uncoupling in space and time of the 'actin cytoskeleton-dependent cytoplasmic pathway of bud development and organelle positioning and inheritance' from the 'microtubule-dependent nuclear division pathway' in a budding yeast cell cycle.
- MeSH
- aktiny genetika metabolismus ultrastruktura MeSH
- aparát dělícího vřeténka genetika metabolismus MeSH
- buněčné dělení MeSH
- cytoplazma metabolismus MeSH
- fluorescenční mikroskopie metody MeSH
- mikrofilamenta genetika metabolismus ultrastruktura MeSH
- mikroskopie elektronová rastrovací transmisní metody MeSH
- mikroskopie elektronová rastrovací metody MeSH
- mikrotubuly genetika metabolismus ultrastruktura MeSH
- mutace MeSH
- Saccharomyces cerevisiae genetika růst a vývoj MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
