RNA interference pathways in filamentous fungi

Abstract

RNA interference is a conserved eukaryotic homology-dependent post-transcriptional gene silencing mechanism. The filamentous fungus Neurospora crassa is one of the first organisms used for RNAi studies. Quelling and Meiotic Silencing by Unpaired DNA (MSUD) are two RNAi related phenomena discovered in Neurospora and their characterizations have contributed significantly to our understanding of RNAi mechanisms in eukaryotes. More recently, a type of DNA damage-induced small RNA, microRNA-like small RNAs and Dicer-independent small silencing RNAs have been discovered in Neurospora crassa which can regulate gene expression. In addition, there are at least six different pathways responsible for the production of these small RNAs, indicating that this fungus is an important model system to study small RNA function and biogenesis. The RNAi studies in other filamentous fungi such as Cryphonectria paracitica and Aspergillus provide evidences that RNAi plays an important role in antiviral defense and RNAi mechanism is widely conserved in filamentous fungi, and RNAi has been commonly used as an efficient tool for studying the gene function. The discovery of the endogenous small RNAs from M. circinelloides further indicates the richness and complex of the RNAi field in eukaryotes.

Histone H3K56 Acetylation Is Required for Quelling-induced Small RNA Production through Its Role in Homologous Recombination

“…Quelling-induced small RNAs and DNA damage induced qiRNAs are produced in Neurospora during the vegetative stage from repetitive DNA loci (4,5). We previously showed that homologous recombination process are essential for the production of these small RNAs and is likely the mechanism to distinguish the repetitive sequences from the rest of the genome.…”

RNA-Mediated Silencing in Algae: Biological Roles and Tools for Analysis of Gene Function

“…Some AGO-Piwi polypeptides function as sRNA-guided endonucleases ("slicers") that cleave complementary transcripts, whereas others appear to lack endonucleolytic activity and may be part of effector complexes involved in nondegradative RNAi processes such as translation repression (10,14,25,30,37,39,45,53,91,92,97). In certain eukaryotes, RDRs also play an important role in RNAi (14,15,51,67) (Fig. 1).…”

“…1). In these organisms, RDR activity may initiate RNAi by producing dsRNA from single-stranded transcripts or dramatically enhance the RNAi response by amplifying the precursors of sRNAs (14,15,51,67).…”

Polymicrobial Infection with Periodontal Pathogens Specifically Enhances MicroRNA miR-146a in ApoE −/− Mice during Experimental Periodontal Disease

“…Recently, miRNAs have been shown to regulate a diverse set of biological functions, including diverse actions such as the regulation of developmental timing, differentiation of cells, and development of cancers (2). Recent studies suggested that bacterial, parasite, and viral infections of mammalian cells and plant cells can modulate miRNA expression (9,24). Importantly, miRNA miR-146a was demonstrated to play an important role in innate immunity by regulating cytokine production in response to microbial ligands by various mechanisms, such as endotoxin tolerance (32) as well as crosstolerance (33).…”