Involvement of the cytoskeleton in the intracellular distribution of mannoproteins in hyphal cells of Candida albicans

Cylindrical growth of fungal hyphae requires spatial organization of secretion to the growing tip. In order to better understand the involvement of the cytoskeleton in the spatial control of the secretion, we examined the effects of two anti-cytoskeletal drugs, benomyl and cytochalasin A, on the intracellular distribution of mannoproteins, a major secreted component of the cell wall, in hyphal cells of the dimorphic yeast Candida albicans. The distribution of the mannoproteins was assessed by epifluorescence microscopy with a fluorescence-labelled lentil lectin (FTTC-LCA). Brefeldin A, an inhibitor of secretory transport, induced a localized accumulation of the mannopolysaccharides near the tip as previously reported (Akashi et al, 1997). Benomyl, an inhibitor of microtubules, disrupted the localized accumulation of the polysaccharides, Cytochalasin A, an inhibitor of actin, caused a localized accumulation of the polysaccharides near the tip, where Golgi-like cisternae were also accumulated. Both cytochalasin A and brefeldin A caused some modifications of the actin network, but neither disturbed the polarization of actin and neither affected the microtubule network. Our results suggested that the microtubules are involved in membrane trafficking in hyphal growth as well as the cell polarity of the hyphae.