The Effects of the F-Actin Inhibitor Latrunculin A on the Pathogenic Yeast <b><i>Cryptococcus neoformans</i></b>

Abstract

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.

Microtubules and Actin Cytoskeleton of Cryptococcus neoformans as Targets for Anticancer Agents to Potentiate a Novel Approach for New Antifungals

“…Actin inhibitor LA [17] inhibited proliferation and cells lysed at areas of cell-wall growth (fig. 1i, j; table 1), as we have recently observed on electron microscopy [9,10]. …”

“…neoformans , IFM 41464 (CUH 34, 48-9943, 881, skin, serotype A), from the Medical Mycology Research Centre, Chiba University, Japan [16] was used. Media and cell cultivation were identical as described [9,10]. …”

“…Methyl benzimidazole-2-ylcarbamate (BCM), vincristine (VINC) and latrunculin A (LA) were used as described [9,10]. Further inhibitors were nocodazole (NOC), thiabendazole (TBZ), docetaxel (DOC) and vinblastine sulfate salt (VINB) from Fluka, paclitaxel (PAC; BioChemica), and chlorpropham [isopropyl N-(3-chlorophenyl) carbamate] (CIPC) and cytochalasin D (CD) from Sigma [11].…”

“…Their effects on the F-actin cytoskeleton (AC) and the cell division of C. neoformans were investigated by fluorescence and phase-contrast microscopy in the search for new antifungal agents for the inhibition of cell division. Previously, C. neoformans was studied by electron microscopy [3], and the effects of some of these inhibitors were monitored [9,10]. Electron microscopy has also been used for examining inhibition in other yeasts [11,12,13,14,15].…”

Effects of cytochalasin E onParacoccidioides brasiliensis

“…According to Kopecká et al . (), after inhibition of F‐actin by latrunculin A in the budding yeast Saccharomyces cerevisiae , chitin synthases in the bud neck can escape and diffuse randomly along the cell surface and synthesize chitin at arbitrary locations.…”