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Therapeutic silencing of an endogenous gene by systemic administration of modified siRNAs



RNA interference (RNAi) holds considerable promise as a therapeutic approach to silence disease-causing genes, particularly those that encode so-called ‘non-druggable’ targets that are not amenable to conventional therapeutics such as small molecules, proteins, or monoclonal antibodies. The main obstacle to achieving in vivo gene silencing by RNAi technologies is delivery. Here we show that chemically modified short interfering RNAs (siRNAs) can silence an endogenous gene encoding apolipoprotein B (apoB) after intravenous injection in mice. Administration of chemically modified siRNAs resulted in silencing of the apoB messenger RNA in liver and jejunum, decreased plasma levels of apoB protein, and reduced total cholesterol. We also show that these siRNAs can silence human apoB in a transgenic mouse model. In our in vivo study, the mechanism of action for the siRNAs was proven to occur through RNAi-mediated mRNA degradation, and we determined that cleavage of the apoB mRNA occurred specifically at the predicted site. These findings demonstrate the therapeutic potential of siRNAs for the treatment of disease.

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  1. 1

    Novina, C. D. & Sharp, P. A. The RNAi revolution. Nature 430, 161–164 (2004)

  2. 2

    Scherr, M., Battmer, K., Dallmann, I., Ganser, A. & Eder, M. Inhibition of GM-CSF receptor function by stable RNA interference in a NOD/SCID mouse hematopoietic stem cell transplantation model. Oligonucleotides 13, 353–363 (2003)

  3. 3

    Song, E. et al. RNA interference targeting Fas protects mice from fulminant hepatitis. Nature Med. 9, 347–351 (2003)

  4. 4

    Reich, S. J. et al. Small interfering RNA (siRNA) targeting VEGF effectively inhibits ocular neovascularization in a mouse model. Mol. Vis. 9, 210–216 (2003)

  5. 5

    Zhang, X. et al. Small interfering RNA targeting heme oxygenase-1 enhances ischemia-reperfusion-induced lung apoptosis. J. Biol. Chem. 279, 10677–10684 (2004)

  6. 6

    Dorn, G. et al. siRNA relieves chronic neuropathic pain. Nucleic Acids Res. 32, e49 (2004)

  7. 7

    Lorenz, C., Hadwiger, P., John, M., Vornlocher, H.-P. & Unverzagt, C. Steroid and lipid conjugates of siRNAs to enhance cellular uptake and gene silencing in liver cells. Bioorg. Med. Chem. Lett. 14, 4975–4977 (2004)

  8. 8

    Burnett, J. R. & Barrett, P. H. Apolipoprotein B metabolism: tracer kinetics, models, and metabolic studies. Crit. Rev. Clin. Lab. Sci. 39, 89–137 (2002)

  9. 9

    Farese, R. V. Jr, Ruland, S. L., Flynn, L. M., Stokowski, R. P. & Young, S. G. Knockout of the mouse apolipoprotein B gene results in embryonic lethality in homozygotes and protection against diet-induced hypercholesterolemia in heterozygotes. Proc. Natl Acad. Sci. USA 92, 1774–1778 (1995)

  10. 10

    Brown, M. S. & Goldstein, J. L. A receptor-mediated pathway for cholesterol homeostasis. Science 232, 34–47 (1986)

  11. 11

    Glueck, C. J. et al. Prospective 10-year evaluation of hypobetalipoproteinemia in a cohort of 772 firefighters and cross-sectional evaluation of hypocholesterolemia in 1,479 men in the National Health and Nutrition Examination Survey I. Metabolism 46, 625–633 (1997)

  12. 12

    Enjoji, M., Wang, F., Nakamuta, M., Chan, L. & Teng, B. B. Hammerhead ribozyme as a therapeutic agent for hyperlipidemia: production of truncated apolipoprotein B and hypolipidemic effects in a dyslipidemia murine model. Hum. Gene Ther. 11, 2415–2430 (2000)

  13. 13

    Linton, M. F. et al. Transgenic mice expressing high plasma concentrations of human apolipoprotein B100 and lipoprotein(a). J. Clin. Invest. 92, 3029–3037 (1993)

  14. 14

    Purcell-Huynh, D. A. et al. Transgenic mice expressing high levels of human apolipoprotein B develop severe atherosclerotic lesions in response to a high-fat diet. J. Clin. Invest. 95, 2246–2257 (1995)

  15. 15

    Jackson, A. L. et al. Expression profiling reveals off-target gene regulation by RNAi. Nature Biotechnol. 21, 635–637 (2003)

  16. 16

    Bridge, A. J., Pebernard, S., Ducraux, A., Nicoulaz, A.-L. & Iggo, R. Induction of an interferon response by RNAi vectors in mammalian cells. Nature Genet. 34, 263–264 (2003)

  17. 17

    Llave, C., Xie, Z., Kasschau, K. D. & Carrington, J. C. Cleavage of Scarecrow-like mRNA targets directed by a class of Arabidopsis miRNA. Science 20, 2053–2056 (2002)

  18. 18

    Yekta, S., Shih, I. H. & Bartel, D. P. MicroRNA-directed cleavage of HOXB8 mRNA. Science 304, 594–596 (2004)

  19. 19

    Damha, M. J. & Ogilvie, K. K. Oligoribonucleotide synthesis. The silyl-phosphoramidite method. Methods Mol. Biol. 20, 81–114 (1993)

  20. 20

    Iyer, R. P., Egan, W., Regan, J. B. & Beaucage, S. L. 3H–1,2-benzodithiole-3-one 1,1-dioxide as an improved sulfurizing reagent in the solid phase synthesis of oligodeoxyribonucleoside phosphorothioates. J. Am. Chem. Soc. 112, 1253–1254 (1990)

  21. 21

    Zlot, C. H. et al. Generation of monoclonal antibodies specific for mouse apolipoprotein B-100 in apolipoprotein B-48-only mice. J. Lipid Res. 40, 76–84 (1999)

  22. 22

    Hammad, S. M. et al. Lipoprotein subclass profiles of hyperlipidemic diabetic mice measured by nuclear magnetic resonance spectroscopy. Metabolism 52, 916–921 (2003)

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We thank P. Sharp for his advice and creative input. We are grateful to J. Maraganore and T. Ulich for their support and encouragement. We would like to thank S. Young for the LF3 anti-mouse apoB antibody; D. Bartel and S. Yekta for advice on the 5′-RACE assay; S. Young and M. Stoffel for valuable discussions; and LipoFIT Analytic GmbH and the Institute for Biophysics and Physical Biochemistry of the University of Regensburg for the characterization of lipoprotein particles by NMR. For technical assistance we thank P. Deuerling, F. Hertel, S. Leuschner, N. Linke, A. Müller, G. Ott, H. Schübel, S. Shanmugam, M. Duckman and C. Auger.

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Competing interests

All authors are employees of Alnylam.

Correspondence to Jürgen Soutschek.

Supplementary information

  1. Supplemental Figure 1

    Specificity of apoB mRNA reduction in wild-type mice. siRNA-mediated reduction of apoB mRNA in liver mRNA pools from wild-type mice that received saline (n=10), Chol-mismatch-siRNA (n=10), and Chol-apoB-1-siRNA (n=10). The apoB mRNA was normalized to 4 reference mRNAs: glyceraldehyde 3-phosphate dehydrogenase (GAPDH), glucose-6-phosphatase (G-6-P), factor VII (FVII) and vascular endothelial growth factor (VEGF). Data represent the mean of three independent measurements. Error bars illustrate the standard deviation of the mean. (JPG 18 kb)

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Further reading

Figure 1: Biodistribution of siRNAs in liver and jejunum.
Figure 2: In vivo silencing of murine apoB mRNA by siRNAs in wild-type mice.
Figure 3: Effects of siRNA administration on apoB-100 protein levels.
Figure 4: Therapeutic reduction of lipoprotein and cholesterol levels after siRNA treatment.
Figure 5: In vivo silencing of murine and human apoB mRNA in mice transgenic for human apoB.
Figure 6: siRNA-mediated cleavage of apoB mRNA in vivo


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