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Wsp1 is downstream of Cin1 and regulates vesicle transport and actin cytoskeleton as an effector of Cdc42 and Rac1 in Cryptococcus neoformans.

ABSTRACT: Human Wiskott-Aldrich syndrome protein (WASP) is a scaffold linking upstream signals to the actin cytoskeleton. In response to intersectin ITSN1 and Rho GTPase Cdc42, WASP activates the Arp2/3 complex to promote actin polymerization. The human pathogen Cryptococcus neoformans contains the ITSN1 homolog Cin1 and the WASP homolog Wsp1, which share more homology with human proteins than those of other fungi. Here we demonstrate that Cin1, Cdc42/Rac1, and Wsp1 function in an effector pathway similar to that of mammalian models. In the cin1 mutant, expression of the autoactivated Wsp1-B-GBD allele partially suppressed the mutant defect in endocytosis, and expression of the constitutively active CDC42(Q61L) allele restored normal actin cytoskeleton structures. Similar phenotypic suppression can be obtained by the expression of a Cdc42-green fluorescent protein (GFP)-Wsp1 fusion protein. In addition, Rac1, which was found to exhibit a role in early endocytosis, activates Wsp1 to regulate vacuole fusion. Rac1 interacted with Wsp1 and depended on Wsp1 for its vacuolar membrane localization. Expression of the Wsp1-B-GBD allele restored vacuolar membrane fusion in the rac1 mutant. Collectively, our studies suggest novel ways in which this pathogenic fungus has adapted conserved signaling pathways to control vesicle transport and actin organization, likely benefiting survival within infected hosts.

SUBMITTER: Shen G

PROVIDER: S-EPMC3318296 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature

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Wsp1 is downstream of Cin1 and regulates vesicle transport and actin cytoskeleton as an effector of Cdc42 and Rac1 in Cryptococcus neoformans.

Shen Gui G Zhou Erxun E Alspaugh J Andrew JA Wang Ping P

Eukaryotic cell 20120210 4

Human Wiskott-Aldrich syndrome protein (WASP) is a scaffold linking upstream signals to the actin cytoskeleton. In response to intersectin ITSN1 and Rho GTPase Cdc42, WASP activates the Arp2/3 complex to promote actin polymerization. The human pathogen Cryptococcus neoformans contains the ITSN1 homolog Cin1 and the WASP homolog Wsp1, which share more homology with human proteins than those of other fungi. Here we demonstrate that Cin1, Cdc42/Rac1, and Wsp1 function in an effector pathway similar ...[more]

PMID: 22327008

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Project description:Resistance to fluconazole (FLC), the most widely used antifungal drug, is typically achieved by altering the azole drug target and/or drug efflux pumps. Recent reports have suggested a link between vesicular trafficking and antifungal resistance. Here, we identified novel Cryptococcus neoformans regulators of extracellular vesicle (EV) biogenesis that impact FLC resistance. In particular, the transcription factor Hap2 does not affect the expression of the drug target or efflux pumps, yet it impacts the cellular sterol profile. Subinhibitory FLC concentrations also downregulate EV production. Moreover, in vitro spontaneous FLC-resistant colonies showed altered EV production, and the acquisition of FLC resistance was associated with decreased EV production in clinical isolates. Finally, the reversion of FLC resistance was associated with increased EV production. These data suggest a model in which fungal cells can regulate EV production in place of regulating the drug target gene expression as a first line of defense against antifungal assault in this fungal pathogen. IMPORTANCE Extracellular vesicles (EVs) are membrane-enveloped particles that are released by cells into the extracellular space. Fungal EVs can mediate community interactions and biofilm formation, but their functions remain poorly understood. Here, we report the identification of the first regulators of EV production in the major fungal pathogen Cryptococcus neoformans. Surprisingly, we uncover a novel role of EVs in modulating antifungal drug resistance. Disruption of EV production was associated with altered lipid composition and changes in fluconazole susceptibility. Spontaneous azole-resistant mutants were deficient in EV production, while loss of resistance restored initial EV production levels. These findings were recapitulated in C. neoformans clinical isolates, indicating that azole resistance and EV production are coregulated in diverse strains. Our study reveals a new mechanism of drug resistance in which cells adapt to azole stress by modulating EV production.

Dataset Information

Wsp1 is downstream of Cin1 and regulates vesicle transport and actin cytoskeleton as an effector of Cdc42 and Rac1 in Cryptococcus neoformans.

Publications

Wsp1 is downstream of Cin1 and regulates vesicle transport and actin cytoskeleton as an effector of Cdc42 and Rac1 in Cryptococcus neoformans.

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