Open AccessInduction of Gene Silencing by Hairpin RNA Expression inTetrahymena thermophilaReveals a Second Small RNAPathway
Author(s) -
Rachel A. Howard-Till,
Meng-Chao Yao
Publication year - 2006
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.01430-06
Subject(s) - biology , argonaute , rna induced transcriptional silencing , trans acting sirna , rna interference , rna silencing , gene silencing , dicer , tetrahymena , rna , rna induced silencing complex , genetics , dna directed rna interference , microbiology and biotechnology , small hairpin rna , gene
Unlike in other eukaryotes, in which it causes gene silencing, RNAinterference (RNAi) has been linked to programmed DNA deletion in theciliateTetrahymena thermophila . Here we have developed anefficient method to inducibly express double-stranded RNA hairpins anddemonstrated that they cause gene silencing through targeted mRNAdegradation in all phases of the life cycle, including growth,starvation, and mating. This technique offers a new tool for genesilencing in this model organism. Induction of RNA hairpins causesdramatic upregulation of Dicer and Argonaute family genes, revealing asystem capable of rapidly responding to double-stranded RNA. Thesehairpins are processed into 23- to 24-nucleotide (nt) small RNAs, whichare distinctly different from the 28- to 30-nt small RNAs known to beassociated with DNA deletion. Thus, two different small RNA pathwaysappear to be responsible for gene silencing and DNA deletion.Surprisingly, expression of the RNA hairpin also causes targeted DNAdeletion during conjugation, although at low efficiencies, whichsuggests a possible crossover of these two molecularpaths.