BioSample

The Horizon Discovery CHO-K1 GS null cell line. Generation of the cell line is described. Gene knockout (KO) of both alleles of the glutamine synthetase (GS) gene was performed on CHO-K1 cell line purchased from the European Collection of Cell Cultures (ECACC). Parental CHO-K1 stock was prepared by single cell dilution and selection of several clones based upon the similarity of growth characteristics compared to the parental CHO-K1 cells. A suitable clone was selected for targeting alongside identification of optimal conditions for antibiotic selection following transfection tests, rAAV transduction tests and antibiotic death curves. The rAAV targeting strategy followed that of Liu et al, 2010 [DOI:10.1002/bit.22654], achieving functional knock-out of CHO GS through the targeted deletion of exon six in the GS gene. After allele 1, the selection marker was removed using Cre recombinase, before allele 2 was targeted using the same strategy. The knockout was genotypically validated using genomic PCR and phenotypically validated using RT-PCR. After engineering the adherent CHO K1 cells, the GS null cells were then adapted to suspension culture in animal component free, chemically defined media. The CHOK1GS_HD cell line is available from Horizon Discovery under accessible terms with minimal licensing restrictions.