Extracellular vesicle-mediated export of fungal RNA

Abstract

Extracellular vesicles (EVs) play an important role in the biology of various organisms, including fungi, in which they are required for the trafficking of molecules across the cell wall. Fungal EVs contain a complex combination of macromolecules, including proteins, lipids and glycans. In this work, we aimed to describe and characterize RNA in EV preparations from the human pathogens Cryptococcus neoformans, Paracoccidiodes brasiliensis and Candida albicans, and from the model yeast Saccharomyces cerevisiae. The EV RNA content consisted mostly of molecules less than 250 nt long and the reads obtained aligned with intergenic and intronic regions or specific positions within the mRNA. We identified 114 ncRNAs, among them, six small nucleolar (snoRNA), two small nuclear (snRNA), two ribosomal (rRNA) and one transfer (tRNA) common to all the species considered, together with 20 sequences with features consistent with miRNAs. We also observed some copurified mRNAs, as suggested by reads covering entire transcripts, including those involved in vesicle-mediated transport and metabolic pathways. We characterized for the first time RNA molecules present in EVs produced by fungi. Our results suggest that RNA-containing vesicles may be determinant for various biological processes, including cell communication and pathogenesis.

Cross-kingdom RNA trafficking and environmental RNAi for powerful innovative pre- and post-harvest plant protection

“…Whether EV-mediated sRNA trafficking is a general pathway for sRNA transfer from pathogens/pests to hosts is unknown. Various RNA molecules, including sRNAs, are present in EVs isolated from human pathogens Cryptococcus neoformans, Paracoccidiodes brasiliensis and Candida albicans , and from the model yeast Saccharomyces cerevisiae [46]. It is possible that EVs mediate RNA export and communication with host cells during infection.…”

Identification of small RNAs in extracellular vesicles from the commensal yeast Malassezia sympodialis

“…EV from microorganisms with thick cell walls, such as Gram-positive bacteria and fungi, have been associated with cytotoxicity, the invasion of host cells, and the transfer of virulence factors2. As seen with exosomes18, fungal EV have been observed to deliver functional messenger (m)RNAs and micro (mi)RNA-like RNAs to recipient cells910.…”

RNA ‘Information Warfare’ in Pathogenic and Mutualistic Interactions

“…In pathogenic fungi, export of other molecules involved in virulence has been long known to occur via exosomes and related extracellular vesicle systems (Box 1) [63]. However, from in vitro cultures one study identified numerous RNAs in the extracellular vesicles of the human pathogenic fungi Candida albicans, Cryptococcus neoformans, and Paracoccidioides brasiliensis, including microRNAs and mRNAs [64]. Similarly, extracellular vesicles containing small RNAs have been reported from important parasitic protozoa such as Leishmania species [65] and Trypanosoma cruzi [66], as well as the nematode Trichuris suis [67].…”

“…Although it has been suggested that some virulence proteins are exported from pathogenic fungi to host plants via extracellular vesicles [89], definitive evidence remains to be presented. Studies of non-plant systems suggest that these vesicles act to export functional nucleic acids, including RNAs, between cells [90], and new data suggest that this includes other organisms (e.g., [64][65][66]69,91]). …”