Single stranded extended dicer substrate agents and methods for the specific inhibition of gene expression

摘要

The invention provides compositions and methods for reducing expression of a target gene in a cell, involving contacting a cell with an isolated double stranded nucleic acid (dsNA) in an amount effective to reduce expression of a target gene in a cell. The dsNAs of the invention possess a single stranded extension (in most embodiments, the single stranded extension comprises at least one modified nucleotide and/or phosphate back bone modification). Such single stranded extended Dicer-substrate siRNAs (DsiRNAs) were demonstrated to be effective RNA inhibitory agents compared to corresponding double stranded DsiRNAs.

主权项

1. An isolated double stranded nucleic acid comprising a first oligonucleotide strand having a 5′ terminus and a 3′ terminus and a second oligonucleotide strand having a 5′ terminus and a 3′ terminus, wherein each said 5′ terminus comprises a 5′ terminal nucleotide and each said 3′ terminus comprises a 3′ terminal nucleotide, wherein:
said first strand is 25-30 nucleotide residues in length, wherein starting from the 5′ terminal nucleotide (position 1) positions 1 to 23 of said first strand comprise at least 8 ribonucleotides; said second strand is 36-66 nucleotide residues in length and, starting from the 3′ terminal nucleotide, comprises at least 8 ribonucleotides in the positions paired with positions 1-23 of said first strand to form a duplex; wherein at least the 3′ terminal nucleotide of said second strand is unpaired with said first strand, and up to 6 consecutive 3′ terminal nucleotides are unpaired with said first strand, thereby forming a 3′ single stranded overhang of 1-6 nucleotides; wherein the 5′ terminus of said second strand comprises from 10-30 consecutive nucleotides which are unpaired with said first strand, thereby forming a 10-30 nucleotide single stranded 5′ overhang; wherein at least the first strand 5′ terminal and 3′ terminal nucleotides are base paired with nucleotides of said second strand when said first and second strands are aligned for maximum complementarity, thereby forming a substantially duplexed region between said first and second strands; and said second strand is sufficiently complementary to a target RNA along at least 19 ribonucleotides of said second strand length to reduce target gene expression when said double stranded nucleic acid is introduced into a mammalian cell.