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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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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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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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Correspondence to Jürgen Soutschek.

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All authors are employees of Alnylam.

Supplementary information

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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Soutschek, J., Akinc, A., Bramlage, B. et al. Therapeutic silencing of an endogenous gene by systemic administration of modified siRNAs. Nature 432, 173–178 (2004).

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