Methods and compositions for enhancing the efficacy and specificity of RNA silencing

摘要

The present invention provides methods of enhancing the efficacy and specificity of RNA silencing. The invention also provides compositions for mediating RNA silencing. In particular, the invention provides siRNAs, siRNA-like molecules, shRNAs, vectors and transgenes having improved specificity and efficacy in mediating silencing of a target gene. Therapeutic methods are also featured.

主权项

1. A method of enhancing the efficacy of an RNAi agent, comprising synthesizing a substituted RNAi agent comprising a sense and an antisense strand, wherein the substituted RNAi agent directs cleavage by a RISC complex at phosphodiester bond within a desired target mRNA that is the same phosphodiester bond at which the RNAi agent directs cleavage by the RISC complex, comprising lessening the base pair strength between the antisense strand 5′ end (AS 5′) and the sense strand 3′ end (S 3′) of the substituted RNAi agent as compared to the base pair strength between the antisense strand 3′ end (AS 3′) and the sense strand 5′ end (S 5′) of the substituted RNAi agent, such that efficacy is enhanced, wherein the base pair strength is lessened due to the introduction of a modification between the AS 5′ and the S 3′, wherein the modification is selected from the group consisting of: (a) at least one mismatched base pair; (b) at least one wobble base pair; (c) at least one mismatched base pair in combination with at least one wobble base pair; (d) at least one base pair comprising a rare nucleotide; and (e) at least one base pair comprising a modified nucleotide selected from the group consisting of 2-amino-G, 2-amino-A, 2,6-diamino-G, and 2,6-diamino-A, such that the base pair strength between the AS 5′ and the S 3′ of the substituted RNAi agent as compared to the base pair strength between the AS 3′ and the S 5′ of the substituted RNAi agent is lessened.