1. Ch 16. Posttranscriptional Regulation RNA interference (RNAi)

2. dsRNA(si RNA)Down regulation of gene expression (Disrupt transcribed mRNA) + Anti-sense RNA+ dsRNA - control+ control

3. dsRNA and 21-23nt RNA fragment

4. siRNA (short interfering RNA) Nuclease (Dicer) 21-23 nt dsRNA (si RNA) Target mRNA disruption (RISC) Trigger ds RNA

5. Dicer & RISC (RNA-induced silencing complex) Argonaute(Slicer) guide strand passenger strand

6. Slicer activity of Argonaute

7. RNAi

8. Effect of RNAi on cell Anti-viral effect (RNA virus) Inhibition of transposition during development Downregulation of transgene and its homolog; shRNA(short hairpin RNA) Heterochromatin & gene inactivation ; Histone and DNA methylation (epigenetic) X-chromosome inactivation Amplification of siRNA

9. RNAi at the centromere: heterochromatin formation RNA-induced initiator of transcriptional gene silencing (RITS)

10. Methylation of regulatory region by siRNA induces gene silencing

11. microRNA (miRNA) Drosha Developmental regulation (Lin, HOX)

12. Pre-miRNA

13. Inhibitory effect of the miRNA during translation