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RNAi A NEW APPROACH TO HEALING

RNAi A NEW APPROACH TO HEALING. Nouna Bakhiet, Ph.D. MESA Faculty Lecture Series Southwestern College Fall 2004. BEING CURRENT. SEPTEMBER 13,2004. STEPPING BACK TO GO FORWARD. UNDERSTANDING THE CENTRAL DOGMA DNA REPLICATION TRANSCRIPTION RNA TRANSLATION PROTEIN.

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RNAi A NEW APPROACH TO HEALING

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  1. RNAi A NEW APPROACH TO HEALING Nouna Bakhiet, Ph.D. MESA Faculty Lecture Series Southwestern College Fall 2004

  2. BEING CURRENT SEPTEMBER 13,2004

  3. STEPPING BACK TO GO FORWARD UNDERSTANDING THE CENTRAL DOGMA DNA REPLICATION TRANSCRIPTION RNA TRANSLATION PROTEIN

  4. MAMMAILAN CELLS keratinocytes fibroblasts macrophages

  5. THE CELL DNA cell nucleus

  6. THE NUCLEUS DNA nucleus

  7. THE DNA

  8. FUNCTIONS OF THE DNA

  9. FUNCTIONS OF THE DNA

  10. HOW TRANSCRIPTION STARTS

  11. AND CONTINUES

  12. AND CONTINUES

  13. AND CONTINUES

  14. TRANSCRIPTION COMPLETED

  15. THE FUNCTION OF RNAi SIMPLY PUT

  16. DOUBLE STANDED RNAi

  17. FROM dsRNA TO siRNA

  18. MODEL OF DICER FUNCTION Hannon, Nature 2002

  19. INTRODUCING DICER • Highly conserved • Specific for dsRNAs • Functions as dimer • Processes siRNAs and microRNAs • Different structural domains • Helicase (+/-ATP-bining motif) • PAZ domain • Tandem RNase III domains • C-reminal dsRNA-binding domain

  20. MODEL OF siRNA FUNCTION Keep this in mind

  21. DEFINING RISC • RNA-Induced Silencing Complex • Multiple protein complex • ATP-dependent endonuclease • Cleaves RNAs • Activated by ATP

  22. RNAi SEQUENCE cDNA cacaaaacgaatgcagcacgtctagcacgttagccaaag iRNA ugcacgagcucuagcagcutt ttacgugcucgagaucgucga target sequence (19-21bases) constant region

  23. Model of Post-Transcriptional Gene Silencing Biological functions: Believed to participate in the regulation of gene expression, And importantly, in maintenance of genomic stability by limiting the “jumping around” of transposable elements and viral replication And incorporation into the genome.

  24. WHAT WE KNOW NOW mRNA targetting Translational repression Transcriptional repression

  25. RNAi SILENCING FUNCTION (in the presence of Dicer) wild-type GFP dsRNA GFP – germline transgene Keep this in mind dcr1 -/-

  26. Uninjected No hybridization probe Uninjected Normal mex3 mRNA staining Injected with anti-sense Mex3 RNA Injected with Mex3 dsRNA dsRNA INDUCES POTENT GENE SILENCING IN C. elegans Keep this in mind Fire et al. Nature 1998

  27. Caenorhabditis elegans

  28. EXPERIMENTALLY INDUCED RNAi IN VARIOUS SYSTEMS Hannon, Nature 2004

  29. Hydrodynamic Transfection in Mice

  30. RNA INTERFERENCE IN ADULT MICE McCaffrey et al. Nature 2002

  31. APPLICATION In the lab • Genetic analysis in model organisms such as C. elegans and Drosophila, and for the analysis of gene function in mammals • These technologies are being used to study the relationship of certain genes with cancer, obesity and aging In the clinic • Therapeutic uses of RNAi are currently being explored with studies using siRNAs to target viruses such as HIV • Major problem is delivery

  32. DELIVERY AND ETHICS • If we start with embryonic cells • Add cDNA encoding dsRNA specific to the target gene • Incorporation into the genome can take place • Leading to an individual in whom the target gene product is absent • This individual will pass on the RNAi sequence upon propagating to all subsequent generations

  33. REFERENCES • Denli & Hannon 2003 TIBS 28 196-201 • Dykxhoorn 2003 Nat Rev Cell Mol Biol 4 457-67 • Hunter & Poethig 2003 Curr Opin Genet Dev 13 372-8 • Samuel 2004 Nat Biotech 22 280-2

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