Single-Stranded Nucleic Acid Molecule for Controlling Gene Expression

Abstract

Provided is a novel nucleic acid molecule that is a single-stranded nucleic acid molecule including an expression inhibitory sequence that inhibits expression of a target gene. The single-stranded nucleic acid molecule includes, in sequence from the 5′ side to the 3′ side: a 5′ side region (Xc); an inner region (Z); and a 3′ side region (Yc). The inner region (Z) is composed of an inner 5′ side region (X) and an inner 3′ side region (Y) that are linked to each other. The 5′ side region (Xc) is complementary to the inner 5′ side region (X). The 3′ side region (Yc) is complementary to the inner 3′ side region (Y). At least one of the inner region (Z), the 5′ side region (Xc), and the 3′ side region (Yc) includes the expression inhibitory sequence.

1 . A single-stranded nucleic acid molecule comprising:
 an expression inhibitory sequence that inhibits expression of a target gene, wherein   the single-stranded nucleic acid molecule comprises, in sequence from a 5′ side to a 3′ side: a 5′ side region (Xc); an inner region (Z); and a 3′ side region (Yc),   the inner region (Z) is composed of an inner 5′ side region (X) and an inner 3′ side region (Y) that are linked to each other,   the 5′ side region (Xc) is complementary to the inner 5′ side region (X),   the 3′ side region (Yc) is complementary to the inner 3′ side region (Y), and   at least one of the inner region (Z), the 5′ side region (Xc), and the 3′ side region (Yc) comprises the expression inhibitory sequence.   
     
     
         2 . The single-stranded nucleic acid molecule according to  claim 1 , further comprising:
 a linker region (Lx) between the 5′ side region (Xc) and the inner 5′ side region (X),   wherein the 5′ side region (Xc) and the inner 5′ side region (X) are linked to each other via the linker region (Lx).   
     
     
         3 . The single-stranded nucleic acid molecule according to  claim 1 , further comprising:
 a linker region (Ly) between the 3′ side region (Yc) and the inner 3′ side region (Y),   wherein the 3′ side region (Yc) and the inner 3′ side region (Y) are linked to each other via the linker region (Ly).   
     
     
         4 . The single-stranded nucleic acid molecule according to  claim 1 , further comprising:
 a linker region (Lx) between the 5′ side region (Xc) and the inner 5′ side region (X); and   a linker region (Ly) between the 3′ side region (Yc) and the inner 3′ side region (Y),   wherein the 5′ side region (Xc) and the inner 5′ side region (X) are linked to each other via the linker region (Lx), and   the 3′ side region (Yc) and the inner 3′ side region (Y) are linked to each other via the linker region (Ly).   
     
     
         5 . The single-stranded nucleic acid molecule according to  claim 1 , wherein the number of bases (Z) in the inner region (Z), the number of bases (X) in the inner 5′ side region (X), the number of bases (Y) in the inner 3′ side region (Y), the number of bases (Xc) in the 5′ side region (Xc), and the number of bases (Yc) in the 3′ side region (Yc) satisfy conditions of Expressions (1) and (2):
     Z=X+Y   (1)
 
     Z≧Xc+Yc   (2)
 
 
     
     
         6 . The single-stranded nucleic acid molecule according to  claim 1 , wherein the number of bases (X) in the inner 5′ side region (X), the number of bases (Xc) in the 5′ side region (Xc), the number of bases (Y) in the inner 3′ side region (Y), and the number of bases (Yc) in the 3′ side region (Yc) satisfy any of conditions (a) to (d):
 (a) Conditions of Expressions (3) and (4) are satisfied;
     X>Xc   (3)
 
     Y=Yc   (4)
 
 
 (b) Conditions of Expressions (5) and (6) are satisfied;
     X=Xc   (5)
 
     Y>Yc   (6)
 
 
 (c) Conditions of Expressions (7) and (8) are satisfied;
     X>Xc   (7)
 
     Y>Yc   (8)
 
 
 (d) Conditions of Expressions (9) and (10) are satisfied;
     X=Xc   (9)
 
     Y=Yc   (10).
 
 
 
     
     
         7 . The single-stranded nucleic acid molecule according to  claim 6 , wherein, in the conditions (a) to (d), the difference between the number of bases (X) in the inner 5′ side region (X) and the number of bases (Xc) in the 5′ side region (Xc), and the difference between the number of bases (Y) in the inner 3′ side region (Y) and the number of bases (Yc) in the 3′ side region (Yc) satisfy the following conditions:
 (a) Conditions of Expressions (11) and (12) are satisfied;
     X−Xc= 1, 2 or 3  (11)
 
     Y−Yc= 0  (12)
 
 
 (b) Conditions of Expressions (13) and (14) are satisfied;
     X−Xc= 0  (13)
 
     Y−Yc= 1, 2 or 3  (14)
 
 
 (c) Conditions of Expressions (15) and (16) are satisfied;
     X−Xc= 1, 2 or 3  (15)
 
     Y−Yc= 1, 2 or 3  (16)
 
 
 (d) Conditions of Expressions (17) and (18) are satisfied;
     X−Xc= 0  (17)
 
     Y−Yc= 0  (18).
 
 
 
     
     
         8 . The single-stranded nucleic acid molecule according to  claim 1 , wherein the number of bases (Z) in the inner region (Z) is 19 or more. 
     
     
         9 . The single-stranded nucleic acid molecule according to  claim 8 , wherein the number of bases (Z) in the inner region (Z) is 19 to 30. 
     
     
         10 . The single-stranded nucleic acid molecule according to  claim 1 , wherein the number of bases (Xc) in the 5′ side region (Xc) is 1 to 11. 
     
     
         11 . The single-stranded nucleic acid molecule according to  claim 10 , wherein the number of bases (Xc) in the 5′ side region (Xc) is 1 to 7. 
     
     
         12 - 26 . (canceled) 
     
     
         27 . A pharmaceutical composition comprising: the single-stranded nucleic acid molecule according to  claim 1 . 
     
     
         28 . A method of treating inflammation in a subject comprising
 administering the pharmaceutical composition according to  claim 27  to the subject.   
     
     
         29 . A method of inhibiting expression of a target gene, the method comprising the step of: using the single-stranded nucleic acid molecule according to  claim 1 . 
     
     
         30 . The method according to  claim 29 , comprising the step of: administering the single-stranded nucleic acid molecule to a cell, a tissue, or an organ. 
     
     
         31 . The method according to  claim 30 , wherein the single-stranded nucleic acid molecule is administered in vivo or in vitro. 
     
     
         32 . The method according to  claim 29 , wherein expression of the gene is inhibited by RNA interference. 
     
     
         33 . A method of inducing RNA interference that inhibits expression of a target gene, the method comprising the step of: using the single-stranded nucleic acid molecule according to  claim 1 . 
     
     
         34 . A method of treating a disease, the method comprising the step of:
 administering the single-stranded nucleic acid molecule according to  claim 1 , to a patient,   wherein the single-stranded nucleic acid molecule comprises, as the expression inhibitory sequence, a sequence that inhibits expression of a gene causing the disease.   
     
     
         35 - 36 . (canceled) 
     
     
         37 . A nucleic acid molecule for use in treatment of a disease, wherein the nucleic acid molecule is the single-stranded nucleic acid molecule according to  claim 1 , and
 the single-stranded nucleic acid molecule comprises, as the expression inhibitory sequence, a sequence that inhibits expression of a gene causing the disease.