Genetic suppression and replacement
Methods and agents for suppressing expression of a mutant allele of a gene and providing a replacement nucleic acid are provided. The methods of the invention provide suppression effectors such as, for example, antisense nucleic acids, ribozymes, or RNAi, that bind to the gene or its RNA. The invention further provides for the introduction of a replacement nucleic acid with modified sequences such that the replacement nucleic acid is protected from suppression by the suppression effector. The replacement nucleic acid is modified at degenerate wobble positions in the target region of the suppression effector and thereby is not suppressed by the suppression effector. In addition, by altering wobble positions, the replacement nucleic acid can still encode a wild type gene product. The invention has the advantage that the same suppression strategy could be used to suppress, in principle, many mutations in a gene. Also disclosed is a transgenic mouse that expresses human rhodopsin (modified replacement gene) and a transgenic mouse that expresses a suppression effector targeting rhodopsin. Also disclosed in intraocular administration of siRNA.
1. A composition comprising:
a) an RNAi suppression effector, or modified version thereof, or a suppression effector encoding an RNAi, that binds to mature RNA transcribed from DNA of a mutant allele of rhodopsin, thereby to inhibit the expression of the mutant allele, wherein said mature RNA comprises the nucleotide sequence CUCUACGUCACCGUC (SEQ ID NO: 176); and
b) a replacement nucleic acid that encodes a wild-type or non-disease causing allele and that comprises five degenerate / wobble nucleotides that are altered so that the replacement nucleic acid is not suppressed, or is only partially suppressed, by the suppression effector.
2. The composition of claim 1 , wherein the suppression effector is operatively linked to an expression vector.
3. The composition of claim 1 , wherein the replacement nucleic acid is operatively linked to an expression vector.
4. A method for preparing a suppression effector and replacement nucleic acid, the method comprising the steps of:
a) preparing an RNAi suppression effector, or modified version thereof, or a suppression effector encoding an RNAi, that binds to mature RNA transcribed from DNA encoding a mutant allele of rhodopsin, thereby to inhibit the expression of the mutant allele;
wherein said mature RNA comprises the nucleotide sequence CUCUACGUCACCGUC (SEQ ID NO: 176) and
b) preparing a replacement nucleic acid that encodes a wild-type or non-disease causing allele and that comprises five degenerate/wobble nucleotides that are altered so that the replacement nucleic acid is not suppressed, or is only partially suppressed, by the suppression effector.
5. A kit comprising:
a) an RNAi suppression effector, or modified version thereof, or a suppression effector encoding an RNAi, that suppresses the expression of a mature RNA transcribed from a DNA encoding a mutant allele of rhodopsin wherein said mature RNA comprises the nucleotide sequence CUCUACGUCACCGUC (SEQ ID NO: 176); and
b) a replacement nucleic acid that encodes a wild-type or non-disease causing allele that is not suppressed, or is only partially suppressed, by the suppression effector and that differs from the mutant allele in five degenerate/wobble nucleotides.
6. The composition of claim 1 , wherein the suppression effector suppresses both alleles of an endogenous gene.
7. An isolated cell expressing (i) an RNAi suppression effector, or modified version thereof, or a suppression effector encoding an RNAi, that targets a mutant allele of rhodopsin, thereby inhibiting the expression of the mutant allele, wherein said suppression effector binds to the mature RNA transcribed from DNA encoding the mutant allele, wherein said mature RNA comprises the nucleotide sequence CUCUACGUCACCGUC (SEQ ID NO: 176); and (ii) a replacement nucleic acid that encodes a wild-type or non-disease causing allele and that comprises five degenerate/wobble nucleotides that are altered so that the replacement nucleic acid is not suppressed, or is only partially suppressed, by the suppression effector.
8. The composition of claim 1 , wherein the replacement nucleic acid encodes mammalian rhodopsin.
9. The composition of claim 1 , wherein the suppression effector encoding an RNAi and replacement nucleic acid are located on the same vector.
10. The method of claim 4 , further comprising the step of transfecting the suppression effector and/or replacement nucleic into a cell using a lipofectamine or oligofectamine product.
11. The composition of claim 1 , wherein the RNAi suppression effector or modified version thereof, or a suppression effector encoding an RNAi, and/or the replacement nucleic acid is naked nucleic acid.
12. The composition of claim 1 , further comprising a lipid, a polymer, a nucleic acid, or another derivative that aids gene delivery or expression of the RNAi suppression effector or modified version thereof, or a suppression effector encoding an RNAi, and/or the replacement nucleic acid.
13. The method of claim 4 , wherein the RNAi suppression effector or modified version thereof, or a suppression effector encoding an RNAi, and/or the replacement nucleic acid is naked nucleic acid.
14. The method of claim 4 , further comprising providing a lipid, a polymer, a nucleic acid, or another derivative that aids gene delivery or expression of the RNAi suppression effector or modified version thereof, or a suppression effector encoding an RNAi, and/or the replacement nucleic acid.
15. The kit of claim 5 , wherein the an RNAi suppression effector or modified version thereof, or a suppression effector encoding an RNAi, and/or the replacement nucleic acid is naked nucleic acid.
16. The kit of claim 5 , further comprising a lipid, a polymer, a nucleic acid, or another derivative that aids gene delivery or expression of the RNAi suppression effector or modified version thereof, or a suppression effector encoding an RNAi, and/or the replacement nucleic acid.
17. The composition of claim 1 , wherein the RNA is an mRNA.
18. The composition of claim 1 , wherein said replacement nucleic acid comprises the nucleotide sequence CTGTATGTGACGGTG (SEQ ID NO: 175) or the corresponding mature RNA sequence thereof.
19. The method of claim 4 , wherein said replacement nucleic acid comprises the nucleotide sequence CTGTATGTGACGGTG (SEQ ID NO: 175) or the corresponding mature RNA sequence thereof.
20. The kit of claim 5 , wherein said replacement nucleic acid comprises the nucleotide sequence CTGTATGTGACGGTG (SEQ ID NO: 175) or the corresponding mature RNA sequence thereof.
21. The isolated cell of claim 7 , wherein said replacement nucleic acid comprises the nucleotide sequence CTGTATGTGACGGTG (SEQ ID NO: 175) or the corresponding mature RNA sequence thereof.