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RRF-1

RRF-1. Ruchira Ranaweera. Clone summary. What is the function of “rrf-1”?. RNA-directed RNA Polymerase Amplifies RNAi silencing Only required for RNAi in somatic cells, NOT germline. What is an RNA-directed RNA Polymerase?. Different from RNA polymerase used in transcription

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RRF-1

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  1. RRF-1 Ruchira Ranaweera

  2. Clone summary

  3. What is the function of “rrf-1”? • RNA-directed RNA Polymerase • Amplifies RNAi silencing • Only required for RNAi in somatic cells, NOT germline

  4. What is an RNA-directed RNA Polymerase? • Different from RNA polymerase used in transcription • RdRp uses RNA as a template to create an RNA copy, or a cRNA • Involved in RNAi amplification causing transitive RNA interference

  5. Blast-n search results • Shows 78% sequence similarity in C. elegans cosmid F26A3 • Best matching ORF was rrf-1 coding region • Chromosome I , +2.23 • exons 12 and 13 • Related gene ego-1, also an RdRP is downstream of rrf-1 in genome

  6. Protein Homology • Putative Conserved RdRp domain found • Extensive homology in nematodes (C. remanei vs. C. elegans, C. briggsae) • Also homologous to other RdRp in plant species (Arabidopsis thaliana, Oryza Sativa)

  7. Protein Sequence Alignment • Highly conserved sequence matches with other RdRp homologs in C. elegans • Conserved across region with RdRp domain

  8. RNA interference • RdRp amplifies siRNA-directed silencing • Produces more copies of long dsRNA using trigger siRNA as a primer which can then be cleaved by Dicer • The new siRNAs have unique specificities • Amplified response allows for degradation of a large amount of dsRNA www.pnas.orgcgidoi10.1073pnas.1232238100 Dillin, A. “The specifics of small interfering RNA specificity”

  9. Why have RNAi? • First line of defense against viruses and transposons • RdRp helps send immune response signal to other cells in organism • Propagates a good adaptive immunity • Vertebrates may have evolved past need for RdRp

  10. Future of RdRp and RNAi • Mutants of rrf-1 • Study selective silencing of genes in germline • Research • Study gene expression and regulation without need for complete gene knockouts • RNAi therapy • Treat genetic diseases where genes have been incorrectly activated

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