Methods and compositions for producing double allele knock outs
The present invention provides a method and compositions utilizing the CRISPR system to disrupt a target gene in eukaryotic cells to produce double allele knock outs. The method finds use in producing afucosylated antibodies with enhanced ADCC activity.
1. A method of producing a double allele knock-out of a target gene in a eukaryotic cell, comprising the steps of: providing the cells with a CRISPR system comprising a wild-type Cas9 nuclease, wherein the Cas9 nuclease has two functional nuclease domains that produce a double-stranded break, and three to seven targeting RNAs located in the same gene, wherein each targeting RNA is comprised of a crRNA and a tracrRNA, wherein each crRNA has a different sequence, and expressing the CRISPR nuclease and the targeting RNAs whereby the target gene is knocked out in both alleles of the cell.
2. The method of claim 1 , wherein each targeting RNA has the same tracrRNA.
3. The method of claim 2 , wherein the targeting RNAs use one of at least two different tracrRNAs.
4. The method of claim 1 , wherein said cells are mammalian.
5. The method of claim 4 , wherein said cells are CHO cells, 293 cells, NS0 cells, embryonic stem cells, or derivatives thereof, or antibody-producing cells or derivatives thereof.
6. The method of claim 1 , wherein the tracrRNA and the crRNA are connected by a hairpin RNA linkage.
7. The method of claim 1 , wherein at least two targeting RNAs is are complementary to a corresponding target sequence in the targeted gene, and wherein the target sequences are in a single exon of the targeted gene.
8. The method of claim 1 , wherein at least two targeting RNAs are complementary to a corresponding target sequence in the targeted gene, and wherein the target sequences are located in a contiguous stretch of 375 bp in the target gene.
9. The method of claim 1 , wherein at least two targeting RNAs are complementary to a corresponding target sequence in the targeted gene, and wherein the target sequences are located in a contiguous stretch of 200 bp in the target gene.
10. The method of claim 1 , wherein at least two targeting RNAs are complementary to a corresponding target sequence in the targeted gene, and wherein the target sequences are located in a contiguous stretch of 150 bp in the target gene.
11. The method of claim 1 , wherein the targeted gene is a fucosyltransferase.
12. The method of claim 1 , wherein the targeted gene is glutamine synthetase.
13. The method of claim 1 , wherein the targeted gene is dihydrofolate reductase (DHFR).
14. The method of claim 1 , wherein the targeted gene is a sialidase.
15. The method of claim 1 , wherein the targeted gene is a Fut8.
16. The method of claim 1 , wherein the target gene is comprised of at least two exons and at least one intron, and wherein at least two targeting RNAs are located in the same exon.
17. The method of claim 1 , wherein the CRISPR system comprises four targeting RNAs located in the same gene.
18. The method of claim 1 , wherein the CRISPR system comprises five targeting RNAs located in the same gene.