Non-coding RNAs in the development and pathogenesis of eukaryotic microbes

Abstract

RNA has long been regarded as the important intermediary in the central dogma of gene expression. Recently, the importance of RNAs in the regulation of gene expression became evident with the identification and characterization of non-protein coding transcripts named non-coding RNAs (ncRNAs). The ncRNAs, small and long, are ubiquitously present in all three domains of life and are being recognized for their important roles in genome defense and development. Some of the ncRNAs have been associated with diseases, and therefore, they offer diagnostic and therapeutic potential. In this mini-review, we have highlighted some recent research on the ncRNAs identified in eukaryotic microbes, with special emphasis on fungi that are pathogenic to humans or plants when possible. It is our contention that further elucidation and understanding of ncRNAs will advance our understanding of the development and pathogenesis of eukaryotic microbes and offer alternatives in the diagnosis and treatment of the diseases caused by these pathogens.

Fig. 1

Quelling in N. crassa: The repetitive DNA is identified and targeted by helicase QDE-3, which recruits the RNA dependent RNA polymerase QDE-1. The aberrant RNA produced by QDE-1 is chopped up into 25nt siRNAs by the dicers DCL1 /DCL2. The siRNAs serve as guide for the RISC complex to target specific sequences for silencing. QDE2 and QIP activate the RISC complex

Fig. 2

Classification of lncRNAs based on their proximity position relative to the target protein coding gene. The lncRNAs are marked in gray and the protein coding genes in black. The arrows indicate the direction of transcription

Fig. 3

The regulation of transcription of the FLO11 gene in S. cerevisiae by two lncRNAs ICR1 and PWR1: The transcription of PWR1 inhibits the transcription of ICR1 and thereby leaves the promoter of FLO11 open for the recruitment of transcription activators. Transcription activator Flo8 and repressor Sfl1 compete for the expression of the lncRNAs. In the absence of PWR1 expression, ICR1 is expressed, leading to dislodging of the transcription machinery from the promoter of FLO11 and thereby the repression of the FLO11 expression