RNAi Interactions with Heterochromatin RNA Editing and DNA Repair

The importance of RNAi to the formation and maintenance of heterochromatin was first discovered in fission yeast (Volpe et al. 2002). The deletion of the RNAi genes argonaute, dicer, and RNA-dependent RNApolymerase caused the de-repression of transgenes located at centromeres, which were otherwise silenced by the heterochromatic environment. Histone methylation patterns were also affected methylation of histone 3 at lysine 9 (H3-mK9) is a heterochromatic marker, while H3-mK4 is preferentially...

RNAiMediated TGS

Double-stranded RNAs can also produce TGS of homologous genomic regions (regions complementary to the siRNAs) in Arabidopsis, Schizosaccharomyces pombe, Drosophila, and mammalian cells (reviewed in Matzke and Birchler 2005). TGS was first observed when doubly transformed tobacco plants surprisingly exhibited a suppressed phenotype of a transgene. Closer examination indicated that observed suppression of the transgene was the result of directed DNA methylation at the transgene loci (Matzke et...

RNAi Important to Maintain Genome Integrity A Primitive Immune System in C elegans

In most C. elegans strains, transposition of the Tc1 transposon happens in somatic cells, but transposon shuffling is completely silenced in the germline. Many genes essential for transposon silencing, called the mutators, are also important for the RNAi pathway (Ketting et al. 1999 Ketting and Plasterk 2000 Tabara et al. 1999 Tijsterman et al. 2002 Vastenhouw et al. 2003). The common requirement of these specific genes in both silencing processes strongly points to the important role played by...