Biomaterial Database

Distinct RNA-dependent RNA polymerases are required for RNAi triggered by double-stranded RNA versus truncated transgenes in Paramecium tetraurelia. 2010

Simone Marker, and Anne Le Mouël, and Eric Meyer, and Martin Simon

Department of Biology, University of Kaiserslautern, Gottlieb-Daimler Street, 67663 Kaiserslautern, Germany.

In many eukaryotes, RNA-dependent RNA polymerases (RdRPs) play key roles in the RNAi pathway. They have been implicated in the recognition and processing of aberrant transcripts triggering the process, and in amplification of the silencing response. We have tested the functions of RdRP genes from the ciliate Paramecium tetraurelia in experimentally induced and endogenous mechanisms of gene silencing. In this organism, RNAi can be triggered either by high-copy, truncated transgenes or by directly feeding cells with double-stranded RNA (dsRNA). Surprisingly, dsRNA-induced silencing depends on the putatively functional RDR1 and RDR2 genes, which are required for the accumulation of both primary siRNAs and a distinct class of small RNAs suggestive of secondary siRNAs. In contrast, a third gene with a highly divergent catalytic domain, RDR3, is required for siRNA accumulation when RNAi is triggered by truncated transgenes. Our data further implicate RDR3 in the accumulation of previously described endogenous siRNAs and in the regulation of the surface antigen gene family. While only one of these genes is normally expressed in any clonal cell line, the knockdown of RDR3 leads to co-expression of multiple antigens. These results provide evidence for a functional specialization of Paramecium RdRP genes in distinct RNAi pathways operating during vegetative growth.

UI	MeSH Term	Description	Entries
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D000953	Antigens, Protozoan	Any part or derivative of any protozoan that elicits immunity; malaria (Plasmodium) and trypanosome antigens are presently the most frequently encountered.	Protozoan Antigens
D000954	Antigens, Surface	Antigens on surfaces of cells, including infectious or foreign cells or viruses. They are usually protein-containing groups on cell membranes or walls and may be isolated.	Cell Surface Antigens,Surface Antigens,Surface Markers, Immunological,Cell Surface Antigen,Immunologic Surface Markers,Markers, Immunological Surface,Surface Antigen,Surface Markers, Immunologic,Antigen, Cell Surface,Antigen, Surface,Antigens, Cell Surface,Immunological Surface Markers,Markers, Immunologic Surface,Surface Antigen, Cell,Surface Antigens, Cell
D012324	RNA-Dependent RNA Polymerase	An enzyme that catalyses RNA-template-directed extension of the 3'- end of an RNA strand by one nucleotide at a time, and can initiate a chain de novo. (Enzyme Nomenclature, 1992, p293)	Nucleoside-Triphosphate:RNA Nucleotidyltransferase (RNA-directed),RNA Replicase,RNA-Dependent RNA Replicase,RNA-Directed RNA Polymerase,RNA Dependent RNA Polymerase,RNA Dependent RNA Replicase,RNA Directed RNA Polymerase,RNA Polymerase, RNA-Dependent,RNA Polymerase, RNA-Directed,RNA Replicase, RNA-Dependent,Replicase, RNA,Replicase, RNA-Dependent RNA
D012330	RNA, Double-Stranded	RNA consisting of two strands as opposed to the more prevalent single-stranded RNA. Most of the double-stranded segments are formed from transcription of DNA by intramolecular base-pairing of inverted complementary sequences separated by a single-stranded loop. Some double-stranded segments of RNA are normal in all organisms.	Double-Stranded RNA,Double Stranded RNA,RNA, Double Stranded
D016805	Paramecium tetraurelia	A species of ciliate protozoa. It is used in biomedical research.	Paramecium tetraurelias,tetraurelias, Paramecium
D018503	Genome, Protozoan	The complete genetic complement contained in a set of CHROMOSOMES in a protozoan.	Protozoan Genome,Genomes, Protozoan,Protozoan Genomes
D019076	Transgenes	Genes that are introduced into an organism using GENE TRANSFER TECHNIQUES.	Recombinant Transgenes,Recombinant Transgene,Transgene,Transgene, Recombinant,Transgenes, Recombinant
D034622	RNA Interference	A gene silencing phenomenon whereby specific dsRNAs (RNA, DOUBLE-STRANDED) trigger the degradation of homologous mRNA (RNA, MESSENGER). The specific dsRNAs are processed into SMALL INTERFERING RNA (siRNA) which serves as a guide for cleavage of the homologous mRNA in the RNA-INDUCED SILENCING COMPLEX. DNA METHYLATION may also be triggered during this process.	Gene Silencing, Post-Transcriptional,Post-Transcriptional Gene Silencing,Co-Suppression,Cosuppression,Posttranscriptional Gene Silencing,RNA Silencing,RNAi,Co Suppression,Gene Silencing, Post Transcriptional,Gene Silencing, Posttranscriptional,Gene Silencings, Posttranscriptional,Interference, RNA,Post Transcriptional Gene Silencing,Post-Transcriptional Gene Silencings,Silencing, Post-Transcriptional Gene