title: Two sets of RNAi components are required for heterochromatin formation in trans triggered by truncated transgenes.
abstract: Across kingdoms, RNA interference (RNAi) has been shown to control gene expression at the transcriptional- or the post-transcriptional level. Here, we describe a mechanism which involves both aspects: truncated transgenes, which fail to produce intact mRNA, induce siRNA accumulation and silencing of homologous loci in trans in the ciliate Paramecium We show that silencing is achieved by co-transcriptional silencing, associated with repressive histone marks at the endogenous gene. This is accompanied by secondary siRNA accumulation, strictly limited to the open reading frame of the remote locus. Our data shows that in this mechanism, heterochromatic marks depend on a variety of RNAi components. These include RDR3 and PTIWI14 as well as a second set of components, which are also involved in post-transcriptional silencing: RDR2, PTIWI13, DCR1 and CID2. Our data indicates differential processing of nascent un-spliced and long, spliced transcripts thus suggesting a hitherto-unrecognized functional interaction between post-transcriptional and co-transcriptional RNAi. Both sets of RNAi components are required for efficient trans-acting RNAi at the chromatin level and our data indicates similar mechanisms contributing to genome wide regulation of gene expression by epigenetic mechanisms.
authors.affiliation: Molecular Cell Dynamics Saarland University, Centre for Human and Molecular Biology, Campus A2 4, 66123 Saarbrücken, Germany Department of Biology, University of Kaiserslautern, Erwin-Schrödinger Straße, Building Nr. 14, 67663 Kaiserslautern, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Götz
authors.affiliation: Molecular Cell Dynamics Saarland University, Centre for Human and Molecular Biology, Campus A2 4, 66123 Saarbrücken, Germany.
authors.forename: Simone
authors.initials: S
authors.lastname: Marker
authors.affiliation: Molecular Cell Dynamics Saarland University, Centre for Human and Molecular Biology, Campus A2 4, 66123 Saarbrücken, Germany Department of Biology, University of Kaiserslautern, Erwin-Schrödinger Straße, Building Nr. 14, 67663 Kaiserslautern, Germany.
authors.forename: Miriam
authors.initials: M
authors.lastname: Cheaib
authors.affiliation: Institute of Biotechnology and Drug Research, Erwin-Schrödinger-Str. 56, 67663 Kaiserslautern, Germany.
authors.forename: Karsten
authors.initials: K
authors.lastname: Andresen
authors.affiliation: Molecular Cell Dynamics Saarland University, Centre for Human and Molecular Biology, Campus A2 4, 66123 Saarbrücken, Germany Department of Biology, University of Kaiserslautern, Erwin-Schrödinger Straße, Building Nr. 14, 67663 Kaiserslautern, Germany.
authors.forename: Simon
authors.initials: S
authors.lastname: Shrestha
authors.affiliation: Cluster of Excellence, Multimodal Computing and Interaction and Max Planck Institute for Informatics Saarland University, Department for Computational Biology and Applied Algorithmics, Campus E1 4, 66123 Saarbrücken, Germany.
authors.forename: Dilip A
authors.initials: DA
authors.lastname: Durai
authors.affiliation: Department for Genetics, Saarland University, Centre for Human and Molecular Biology, Campus A2 4, 66123 Saarbrücken, Germany.
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Nordström
authors.affiliation: Cluster of Excellence, Multimodal Computing and Interaction and Max Planck Institute for Informatics Saarland University, Department for Computational Biology and Applied Algorithmics, Campus E1 4, 66123 Saarbrücken, Germany.
authors.forename: Marcel H
authors.initials: MH
authors.lastname: Schulz
authors.affiliation: Molecular Cell Dynamics Saarland University, Centre for Human and Molecular Biology, Campus A2 4, 66123 Saarbrücken, Germany martin.simon@uni-saarland.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Simon
mesh_terms: D042002:Chromatin Assembly and Disassembly; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D063990:Gene Ontology; D006570:Heterochromatin / Q000737:chemistry / Q000378:metabolism*; D058977:Molecular Sequence Annotation; D010247:Paramecium / Q000235:genetics* / Q000378:metabolism; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D011062:Polynucleotide Adenylyltransferase / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference; D012330:RNA, Double-Stranded / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D019076:Transgenes
chemical_list: D004268:DNA-Binding Proteins; D006570:Heterochromatin; D015800:Protozoan Proteins; D012330:RNA, Double-Stranded; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D014157:Transcription Factors; D011062:Polynucleotide Adenylyltransferase