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RNA INTERFERENCE

RNA INTERFERENCE. Pigment enhancing gene. Accidental Discovery. Control. Mex-3 antisense RNA. Mex-3 antisense + sense RNA. Nobel Prize for Medicine-2006 Fire and Mello. mex-3 , highly expressed in C. elegans embryos. RNA Interference.

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RNA INTERFERENCE

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  1. RNA INTERFERENCE

  2. Pigment enhancing gene Accidental Discovery

  3. Control Mex-3 antisense RNA Mex-3 antisense + sense RNA Nobel Prize for Medicine-2006Fire and Mello mex-3, highly expressed in C. elegans embryos

  4. RNA Interference The phenomenon where double stranded RNA causes the silencing of genes by targeting complimentary mRNA for degradation. Widely found in eukaryotic species (fungus, plants and animals)

  5. Sources of double stranded RNA • MicroRNAs (miRNAs) • Viruses • Jumping genes

  6. MicroRNAs (miRNAs) • Derived from ~70 nt pre-miRNAs • 21-23 nucleotides (nt) in length • Two base pair overhangs • Transcribed by RNA polymerase II • Do not encode a protein • Many found in the intronic regions of genes

  7. RNA INTERFERENCE

  8. Two Modes of RNA Interference

  9. miRNAs as a Therapeutic Tool Every disease caused by activity of one or a few genes • Cancer • Autoimmune diseases • Dominant genetic disorders • Viral infections

  10. siRNA therapy for hypercholestrolemia Synthesis of siRNA for mouse apoB Chemical modification to prevent from degradation Injection in tails of mice Within 24 hours serum LDL reduced by over 50%

  11. siRNA therapy for ALS Define optimum anti-SOD1 siRNA sequences in tissue culture Incorporate sequence in retroviral vector Injection into spinal cord of mutant mice Retardation in onset and progression of ALS

  12. RNAi & Age-related Macular Degeneration (AMD) • Over expression of vascular endothelial growth factor (VEGF) • siRNA against the VEGF gene • Inject directly into the eye • Suppression of VEGF protein • Suppression of angiogenesis in the eye Human clinical trials successful

  13. RNAi: The obstacles • Delivery to the desired cell type, tissue or organ • Stimulation of innate immune response • Suppression of off-targets

  14. STEM CELL THERAPY

  15. Stem Cells Stem cells are • Unspecialized • have the ability to divide and renew themselves indefinitely • can differentiate into one or more specialized cell types

  16. Growth pattern of a stem cell

  17. Fertilized egg TOTIPOTENT Types of stem cells Inner cell mass Embryonic stem cells PLURIPOTENT Blastocyst Embryonic germ cells PLURIPOTENT Fetus Adult stem cells MULTIPOTENT or UNIPOTENT

  18. Stem Cell Research Two types of cells • Embryonic stem (ES) cells • Adult stem cells

  19. ES Cells • are derived from the inner mass of a blastocyst • are capable of unlimited cell division • are pluripotent • express the transcription factor Oct-4

  20. Adult stem cells • Generate cells to replace those lost through normal wear and tear, injury or disease • Are identified by the tissue from which they originated. • are found in minute quantities in the bone marrow, blood, cornea, retina, skeletal muscle, liver, skin, brain etc. • Can be made to differentiate into different cells under specific experimental conditions

  21. Potential uses of stem cells • Therapeutic Cloning: Treat human diseases and injuries where the damaged cells or tissues cannot heal or renew themselves • Study basic genetic mechanisms responsible for the processes of development and differentiation. • Test different substances (drugs and chemicals) on stem cells.

  22. THERAPEUTIC CLONING

  23. REPRODUCTIVE CLONING

  24. Advantages and Disadvantages of Embryonic and Adult Stem Cells

  25. Potential diseases treatable by stem cells

  26. Focus of Stem Cell Research • determining precisely how stem cells remain unspecialized and self renewing for many years • identifying the signals (internal as well as external) that cause stem cells to become specialized cells

  27. Stem cells therapy: Ethical considerations

  28. Induced Pluripotent Stem Cells (iPSCs) 2006: Adult mouse fibroblasts converted to pluripotent cells (iPS cells) on injection with genes coding for four transcription factors (Oct-3/4, SOX2, c-Myc, and Klf4). 2007: iPS cells could give rise to all cell types and grown into baby mice when injected into a mouse blastocyst 2008: Skin cells from 80 year old ALS patient converted to iPS cells

  29. stem cell therapy… Success stories!! July 2011 November 2008

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