RNA Interference Mediated Inhibition of Gene Expression Using Short Interfering Nucleic Acid (siNA)
This invention relates to compounds, compositions, and methods useful for modulating gene expression using short interfering nucleic acid (siNA) molecules. In particular, the instant invention features small nucleic acid molecules, such as short interfering nucleic acid (siNA), short interfering RNA (siRNA), double-stranded RNA (dsRNA), micro-RNA (miRNA), and short hairpin RNA (shRNA) molecules and methods used to modulate the expression of genes, such as expressed pseudogenes associated with the maintenance or development of diseases, disorders, traits, and conditions in a subject or organism. The invention also provides small nucleic acid molecules with reduced or attenuated immunostimulatory properties and methods for designing and synthesizing such small nucleic acid molecules having improved toxicologic properties while retaining RNAi activity.
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32 . A method for generating a chemically modified double stranded nucleic acid molecule that directs cleavage of a target RNA via RNA interference (RNAi) that has diminished capacity to induce an interferon response compared to an unmodified double stranded ribonucleic acid molecule, comprising:
a) introducing modified nucleotides into the double stranded nucleic acid molecule, such that
(i) the nucleic acid molecule comprises a sense strand and a separate antisense strand, each strand having one or more pyrimidine nucleotides and one or more purine nucleotides;
(ii) each strand of the nucleic acid molecule is independently 18 to 27 nucleotides in length;
(iii) an 18 to 27 nucleotide sequence of the antisense strand of the nucleic acid molecule is complementary to a human RNA sequence;
(iv) an 18 to 27 nucleotide sequence of the sense strand of the nucleic acid molecule is complementary to the antisense strand and comprises an 18 to 27 nucleotide sequence of the human RNA sequence;
(v) about 50 to 100 percent of the nucleotides in the sense strand and about 50 to 100 percent of the nucleotides in the antisense strand are chemically modified with modifications independently selected from the group consisting of 2′-O-methyl, 2′-deoxy-2′-fluoro, 2′-deoxy, phosphorothioate and deoxyabasic modifications; and
(vi) one or more of the purine nucleotides present in one or both strands of the nucleic acid molecule are 2′-O-methyl purine nucleotides and one or more of the pyrimidine nucleotides present in one or both strands of the nucleic acid molecule are 2′-deoxy-2′-fluoro pyrimidine nucleotides,
and
b) comparing the capacity to induce an interferon response of the chemically modified double stranded nucleic acid molecule of (a) with the capacity to induce an interferon response of the unmodified double stranded ribonucleic acid molecule,
wherein the unmodified double stranded ribonucleic acid molecule has the same nucleotide base sequence as the chemically modified nucleic acid molecule.
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38 . The method of claim 32 , wherein said interferon comprises interferon alpha.