title: Extremely stable Piwi-induced gene silencing in Caenorhabditis elegans.
abstract: In recent years, the Piwi pathway has been shown to regulate the silencing of mobile genetic elements. However, we know little about how Piwi pathways impose silencing and even less about trans-generational stability of Piwi-induced silencing. We demonstrate that the Caenorhabditis elegans Piwi protein PRG-1 can initiate an extremely stable form of gene silencing on a transgenic, single-copy target. This type of silencing is faithfully maintained over tens of generations in the absence of a functional Piwi pathway. Interestingly, RNAi can also trigger permanent gene silencing of a single-copy transgene and the phenomenon will be collectively referred to as RNA-induced epigenetic silencing (RNAe). RNAe can act in trans and is dependent on endogenous RNAi factors. The involvement of factors known to act in nuclear RNAi and the fact that RNAe is accompanied by repressive chromatin marks indicate that RNAe includes a transcriptional silencing component. Our results demonstrate that, at least in C. elegans, the Piwi pathway can impose a state of gene silencing that borders on 'permanently silent'. Such a property may be more widely conserved among Piwi pathways in different animals.
authors: Hubrecht Institute-KNAW and University Medical Centre Utrecht, Utrecht, The Netherlands.
authors: Maartje J
authors: MJ
authors: Luteijn
authors: Petra
authors: P
authors: van Bergeijk
authors: Lucas J T
authors: LJ
authors: Kaaij
authors: Miguel Vasconcelos
authors: MV
authors: Almeida
authors: Elke F
authors: EF
authors: Roovers
authors: Eugene
authors: E
authors: Berezikov
authors: René F
authors: RF
authors: Ketting
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D060565:Argonaute Proteins / Q000378:metabolism*; D017173:Caenorhabditis elegans / Q000201:enzymology* / Q000502:physiology*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D020869:Gene Expression Profiling; D020868:Gene Silencing; D008954:Models, Biological
chemical_list: D060565:Argonaute Proteins; D029742:Caenorhabditis elegans Proteins; C530363:PRG-1 protein, C elegans