Ecdysone receptor-based inducible gene expression system
View Patent ↗This invention relates to the field of biotechnology or genetic engineering. Specifically, this invention relates to the field of gene expression. More specifically, this invention relates to a novel inducible gene expression system and methods of modulating gene expression in a host cell for applications such as gene therapy, large scale production of proteins and antibodies, cell-based high throughput screening assays, functional genomics and regulation of traits in transgenic plants and animals.
1. An isolated mammalian cell comprising a gene expression modulation system comprising:
(a) a first gene expression cassette that is capable of being expressed in said mammalian cell comprising a polynucleotide sequence that encodes a first polypeptide comprising:
(i) a DNA-binding domain that recognizes a response element associated with a gene whose expression is to be modulated;
(ii) an ecdysone receptor ligand binding domain;
(b) a second gene expression cassette that is capable of being expressed in said mammalian cell comprising a polynucleotide sequence that encodes a second polypeptide comprising:
(i) a transactivation domain; and
(ii) a retinoid X receptor ligand binding domain;
wherein the transactivation domain is from a nuclear receptor other than an ecdysone receptor, a retinoid X receptor, or an ultraspiracle receptor,
wherein the ligand binding domains from the first polypeptide and the second polypeptide are different and dimerize
wherein at least one of the first polypeptide and the second polypeptide does not contain the A and B domains of the corresponding ecdysone receptor or retinoid X receptor, and
wherein said gene expression modulation system is more sensitive to a diacylhydrazine ligand than to a steroid ligand when expressed in a mammalian cell.
2. The isolated mammalian cell according to claim 1 , wherein said gene expression modulation system further comprises a third gene expression cassette comprising:
(i) a response element to which the DNA-binding domain of the first polypeptide binds;
(ii) a promoter that is activated by the transactivation domain of the second polypeptide; and
(iii) the gene whose expression is to be modulated.
3. The isolated mammalian cell according to claim 1 , wherein the ligand binding domain of the first polypeptide is encoded by a polynucleotide comprising a nucleic acid sequence selected from the group consisting of SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, and SEQ ID NO: 10.
4. The isolated mammalian cell according to claim 1 , wherein the ligand binding domain of the first polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18, SEQ ID NO: 19, and SEQ ID NO: 20.
5. The isolated mammalian cell according to claim 1 , wherein the ligand binding domain of the second polypeptide is encoded by a polynucleotide comprising a nucleic acid sequence selected from the group consisting of SEQ ID NO: 21, SEQ ID NO: 22, SEQ ID NO: 23, SEQ ID NO: 24, SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO:28, SEQ ID NO: 29, and SEQ ID NO: 30.
6. The isolated mammalian cell according to claim 1 , wherein the ligand binding domain of the second polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 31, SEQ ID NO: 32, SEQ ID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO 37, SEQ ID NO 38, SEQ ID NO: 39, and SEQ ID NO: 40.
7. An isolated mammalian cell comprising a gene expression modulation system comprising:
(a) a first gene expression cassette that is capable of being expressed in said mammalian cell comprising a polynucleotide sequence that encodes a first polypeptide comprising:
(i) a DNA-binding domain that recognizes a response element associated with a gene whose expression is to be modulated; and
(ii) a retinoid X receptor ligand binding domain; and
(b) a second gene expression cassette that is capable of being expressed in said mammalian cell comprising a polynucleotide sequence that encodes a second polypeptide comprising:
(i) a transactivation domain; and
(ii) an ecdysone receptor ligand binding domain;
wherein the ligand binding domains from the first polypeptide and the second polypeptide are different and dimerize, and
wherein at least one of the first polypeptide and the second polypeptide does not contain the A and B domains of the corresponding retinoid X receptor or ecdysone receptor, and
wherein said gene expression modulation system is more sensitive to a diacylhydrazine ligand than to a steroid ligand when expressed in a mammalian cell.
8. The isolated mammalian cell according to claim 7 , further comprising a third gene expression cassette comprising:
(i) a response element to which the DNA-binding domain of the first polypeptide binds;
(ii) a promoter that is activated by the transactivation domain of the second polypeptide; and
(iii) the gene whose expression is being modulated.
9. The isolated mammalian cell according to claim 7 , wherein the ligand binding domain of the first polypeptide is encoded by a polynucleotide comprising a nucleic acid sequence selected from the group consisting of SEQ ID NO: 21, SEQ ID NO: 22, SEQ ID NO: 23, SEQ ID NO: 24, SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO:28, SEQ ID NO: 29, and SEQ ID NO: 30.
10. The isolated mammalian cell according to claim 7 , wherein the ligand binding domain of the first polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID NO: 31, SEQ ID NO: 32, SEQ ID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO 37, SEQ ID NO 38, SEQ ID NO: 39, and SEQ ID NO: 40.
11. The isolated mammalian cell according to claim 7 , wherein the ligand binding domain of the second polypeptide is encoded by a polynucleotide comprising a nucleic acid sequence selected from the group consisting of SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, and SEQ ID NO: 10.
12. The isolated mammalian cell according to claim 7 , wherein the ligand binding domain of the second polypeptide comprises an amino acid sequence selected from the group consisting of SEQ ID No 11, SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18, SEQ ID NO: 19, and SEQ ID NO: 20.
13. The isolated mammalian cell of claim 1 , wherein said first gene expression cassette comprises a polynucleotide encoding a hybrid polypeptide comprising a DNA-binding domain encoded by a polynucleotide comprising a nucleic acid sequence selected from the group consisting of GAL4 DBD (SEQ ID NO: 41) or a LexA DBD (SEQ ID NO: 43) and an ecdysone receptor ligand binding domain encoded by a polynucleotide comprising a nucleic acid sequence selected from the group consisting of SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, and SEQ ID NO: 10.
14. The isolated mammalian cell of claim 1 , wherein said first gene expression cassette comprises a polynucleotide encoding a hybrid polypeptide comprising a DNA-binding domain comprising an amino acid sequence selected from the group consisting of a GAL4 DBD (SEQ ID NO: 42) or a LexA DBD (SEQ ID NO: 44) and an ecdysone receptor ligand binding domain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18, SEQ ID NO: 19, and SEQ ID NO: 20.
15. The isolated mammalian cell of claim 7 , wherein said first gene expression cassette comprises a polynucleotide encoding a hybrid polypeptide comprising a DNA-binding domain encoded by a polynucleotide comprising a nucleic acid sequence selected from the group consisting of a GAL4 DBD (SEQ ID NO: 41) or a LexA DBD (SEQ ID NO: 43) and a retinoid X receptor ligand binding domain encoded by a polynucleotide comprising a nucleic acid sequence selected from the group consisting of SEQ ID NO: 21, SEQ ID NO: 22, SEQ ID NO: 23, SEQ ID NO: 24, SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO:28, SEQ ID NO: 29, and SEQ ID NO: 30.
16. The isolated mammalian cell of claim 7 , wherein said first gene expression cassette comprises a polynucleotide encoding a hybrid polypeptide comprising a DNA-binding domain comprising an amino acid sequence selected from the group consisting of a GAL4 DBD (SEQ ID NO: 42) or a LexA DBD (SEQ ID NO: 44) and a retinoid X receptor ligand binding domain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 31, SEQ ID NO: 32, SEQ ID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO 37, SEQ ID NO 38, SEQ ID NO: 39, and SEQ ID NO: 40.
17. The isolated mammalian cell of claim 7 , wherein said second gene expression cassette comprises a polynucleotide encoding a hybrid polypeptide comprising a transactivation domain encoded by a polynucleotide comprising a nucleic acid sequence of SEQ ID NO: 45 and an ecdysone receptor ligand binding domain encoded by a polynucleotide comprising a nucleic acid sequence selected from the group consisting of SEQ ID NO: 1, SEQ ID NO: 2, SEQ ID NO: 3, SEQ ID NO: 4, SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8, SEQ ID NO: 9, and SEQ ID NO: 10.
18. The isolated mammalian cell of claim 7 , wherein said second gene expression cassette comprises a polynucleotide encoding a hybrid polypeptide comprising a transactivation domain comprising an amino acid sequence of SEQ ID NO: 46 and an ecdysone receptor ligand binding domain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO: 17, SEQ ID NO: 18, SEQ ID NO: 19, and SEQ ID NO: 20.
19. The isolated mammalian cell of claim 1 , wherein said second gene expression cassette comprises a polynucleotide encoding a hybrid polypeptide comprising a transactivation domain encoded by a polynucleotide comprising a nucleic acid sequence of SEQ ID NO: 45 and a retinoid X receptor ligand binding domain encoded by a polynucleotide comprising a nucleic acid sequence selected from the group consisting of SEQ ID NO: 21, SEQ ID NO: 22, SEQ ID NO: 23, SEQ ID NO: 24, SEQ ID NO: 25, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO:28, SEQ ID NO: 29, and SEQ ID NO: 30.
20. The isolated mammalian cell of claim 1 , wherein said second gene expression cassette comprises a polynucleotide encoding a hybrid polypeptide comprising a transactivation domain comprising an amino acid sequence of SEQ ID NO: 46 and a retinoid X receptor ligand binding domain comprising an amino acid sequence selected from the group consisting of SEQ ID NO: 31, SEQ ID NO: 32, SEQ ID NO: 33, SEQ ID NO: 34, SEQ ID NO: 35, SEQ ID NO: 36, SEQ ID NO 37, SEQ ID NO 38, SEQ ID NO: 39, and SEQ ID NO: 40.
21. The mammalian cell of claim 1 , wherein said mammalian cell is a human cell.
22. The mammalian cell of claim 1 , wherein said mammalian cell is a murine cell.
23. The mammalian cell of claim 7 , wherein said mammalian cell is a human cell.
24. The mammalian cell of claim 7 , wherein said mammalian cell is a murine cell.
25. The isolated mammalian cell of claim 1 , wherein said first polypeptide does not contain the ecdysone receptor A and B domains, and said second polypeptide does not contain the retinoid X receptor A and B domains.
26. The isolated mammalian cell of claim 7 , wherein said first polypeptide does not contain the retinoid X receptor A and B domains, and said second polypeptide does not contain the ecdysone receptor A and B domains.
27. The isolated mammalian cell of claim 1 , wherein said diacylhydrazine ligand is a compound of the formula
wherein:
E is a (C4-C6)alkyl containing a tertiary carbon or a cyano(C 3 -C 5 ) alkyl containing a tertiary carbon;
R 1 is H, Me, Et, i-Pr, F, formyl, CF 3 , CHF 2 , CHCl 2 , CH 2 F, CH 2 Cl, CH 2 OH, CH 2 OMe, CH 2 CN, CN, C≡CH, 1-propynyl, 2-propynyl, vinyl, OH, OMe, OEt, cyclopropyl, CF 2 CF 3 , CH═CHCN, allyl, azido, SCN, or SCHF 2 ;
R 2 is H, Me, Et, n-Pr, i-Pr, formyl, CF 3 , CHF 2 , CHCl 2 , CH 2 F, CH 2 Cl, CH 2 OH, CH 2 OMe, CH 2 CN, CN, C≡CH, 1-propynyl, 2-propynyl, vinyl, Ac, F, Cl, OH, OMe, OEt, O-n-Pr, OAc, NMe 2 , NEt 2 , SMe, SEt, SOCF 3 , OCF 2 CF 2 H, COEt, cyclopropyl, CF 2 CF 3 , CH═CHCN, allyl, azido, OCF 3 , OCHF 2 , O-i-Pr, SCN, SCHF 2 , SOMe, NH—CN, or joined with R 3 and the phenyl carbons to which R 2 and R 3 are attached to form an ethylenedioxy, a dihydrofuryl ring with the oxygen adjacent to a phenyl carbon, or a dihydropyryl ring with the oxygen adjacent to a phenyl carbon;
R 3 is H, Et, or joined with R 2 and the phenyl carbons to which R 2 and R 3 are attached to form an ethylenedioxy, a dihydrofuryl ring with the oxygen adjacent to a phenyl carbon, or a dihydropyryl ring with the oxygen adjacent to a phenyl carbon;
R 4 , R 5 , and R 6 are independently H, Me, Et, F, Cl, Br, formyl, CF 3 , CHF 2 , CHCl 2 , CH 2 F, CH 2 Cl, CH 2 OH, CN, C≡CH, 1-propynyl, 2-propynyl, vinyl, OMe, OEt, SMe, or SEt.
28. The isolated mammalian cell of claim 7 , wherein said diacylhydrazine ligand is a compound of the formula
wherein:
E is a (C4-C6)alkyl containing a tertiary carbon or a cyano(C 3 -C 5 ) alkyl containing a tertiary carbon;
R 1 is H, Me, Et, i-Pr, F, formyl, CF 3 , CHF 2 , CHCl 2 , CH 2 F, CH 2 Cl, CH 2 OH, CH 2 OMe, CH 2 CN, CN, C≡CH, 1-propynyl, 2-propynyl, vinyl, OH, OMe, OEt, cyclopropyl, CF 2 CF 3 , CH═CHCN, allyl, azido, SCN, or SCHF 2 ;
R 2 is H, Me, Et, n-Pr, i-Pr, formyl, CF 3 , CHF 2 , CHCl 2 , CH 2 F, CH 2 Cl, CH 2 OH, CH 2 OMe, CH 2 CN, CN, C≡CH, 1-propynyl, 2-propynyl, vinyl, Ac, F, Cl, OH, OMe, OEt, O-n-Pr, OAc, NMe 2 , NEt 2 , SMe, SEt, SOCF 3 , OCF 2 CF 2 H, COEt, cyclopropyl, CF 2 CF 3 , CH═CHCN, allyl, azido, OCF 3 , OCHF 2 , O-i-Pr, SCN, SCHF 2 , SOMe, NH—CN, or joined with R 3 and the phenyl carbons to which R 2 and R 3 are attached to form an ethylenedioxy, a dihydrofuryl ring with the oxygen adjacent to a phenyl carbon, or a dihydropyryl ring with the oxygen adjacent to a phenyl carbon;
R 3 is H, Et, or joined with R 2 and the phenyl carbons to which R 2 and R 3 are attached to form an ethylenedioxy, a dihydrofuryl ring with the oxygen adjacent to a phenyl carbon, or a dihydropyryl ring with the oxygen adjacent to a phenyl carbon;
R 4 , R 5 , and R 6 are independently H, Me, Et, F, Cl, Br, formyl, CF 3 , CHF 2 , CHCl 2 , CH 2 F, CH 2 Cl, CH 2 OH, CN, C≡CH, 1-propynyl, 2-propynyl, vinyl, OMe, OEt, SMe, or SEt.