The RNA Interference Pathway in Trypanosoma brucei
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In most eukaryotic cells, expression or delivery of long double-stranded RNA (dsRNA) signals the presence of foreign and/or potentially dangerous nucleic acids, such as viruses or transcripts derived from retroposons and transposons. As a consequence cells go on red alert and activate specific defense mechanisms to eliminate the invaders. Among such mechanisms is the RNA interference (RNAi) pathway, which is triggered by long dsRNAs, destroys target transcripts in a sequence-specific manner, and is widespread throughout eukaryotic evolution. Here we summarize our current understanding of the RNAi mechanism in Trypanosoma brucei, a protozoan parasite and early divergent eukaryote, and highlight similarities and differences with the RNAi machinery and its function in higher eukaryotes.
KeywordsArgonaute Dicer RNAi genes siRNA
Note added in proof
Our laboratory recently reported the characterization of two novel and essential RNAi factors, namely TbRIF4, a 3′–5′ exonuclease of the DnaQ superfamily with a critical role in the conversion of duplex siRNAs to the single-stranded form, and TbRIF5, a possible TbDCL1 cofactor (Barnes et al. 2012).
Acknowledgments Research in the author’s laboratory was supported by Public Health Service grants AI28798 and AI56333 to E.U and AI43594 to C.T.
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