Preselection of recombinant gene integration sites enabling high transcription rates in CHO cells using alternate start codons and recombinase mediated cassette exchange.

Site-specific recombinase mediated cassette exchange (RMCE) enables the transfer of the gene of interest (GOI) into pre-selected genomic locations with defined expression properties. For the generation of recombinant production cell lines, this has the advantage that screening for high transcription rates at the genome integration site would be required only once, with the possibility to reuse the selected site for new products. Here, we describe a strategy that aims at the selection of transcriptionally active genome integration sites in Chinese Hamster Ovary (CHO) cells by using alternate start codons in the surface reporter protein CD4, in combination with FACS sorting for high expressers.

The external gate of the human and Drosophila serotonin transporters requires a basic/acidic amino acid pair for 3,4-methylenedioxymethamphetamine (MDMA) translocation and the induction of substrate efflux.

The substituted amphetamine, 3,4-methylenedioxy-methamphetamine (MDMA, ecstasy), is a widely used drug of abuse that induces non-exocytotic release of serotonin, dopamine, and norepinephrine through their cognate transporters as well as blocking the reuptake of neurotransmitter by the same transporters. The resulting dramatic increase in volume transmission and signal duration of neurotransmitters leads to psychotropic, stimulant, and entactogenic effects. The mechanism by which amphetamines drive reverse transport of the monoamines remains largely enigmatic, however, promising outcomes for the therapeutic utility of MDMA for post-traumatic stress disorder and the long-time use of the dopaminergic and noradrenergic-directed amphetamines in treatment of attention-deficit hyperactivity disorder and narcolepsy increases the importance of understanding this phenomenon.

Chinese hamster ovary (CHO) host cell engineering to increase sialylation of recombinant therapeutic proteins by modulating sialyltransferase expression.

N-Glycans of human proteins possess both α2,6- and α2,3-linked terminal sialic acid (SA). Recombinant glycoproteins produced in Chinese hamster overy (CHO) only have α2,3-linkage due to the absence of α2,6-sialyltransferase (St6gal1) expression. The Chinese hamster ST6GAL1 was successfully overexpressed using a plasmid expression vector in three recombinant immunoglobulin G (IgG)-producing CHO cell lines.

Overexpression of Serpinb1 in Chinese hamster ovary cells increases recombinant IgG productivity.

We report the discovery and validation of a novel CHO cell engineering target for improving IgG expression, serpin peptidase inhibitor, clade B, member 1 (Serpinb1). Transcriptomic studies using microarrays revealed that Serpinb1 was up-regulated in cultures with IgG heavy and light chain transcription transiently repressed compared with cultures treated with non-targeting siRNA. As proof of concept, a lentiviral vector was employed to overexpress the Chinese Hamster Serpinb1 in a CHOZN(®) Glutamine Synthetase (-/-) recombinant IgG producing CHO line.

The GalNAc-type O-Glycoproteome of CHO cells characterized by the SimpleCell strategy.

The Chinese hamster ovary cell (CHO) is the major host cell factory for recombinant production of biological therapeutics primarily because of its "human-like" glycosylation features. CHO is used for production of several O-glycoprotein therapeutics including erythropoietin, coagulation factors, and chimeric receptor IgG1-Fc-fusion proteins, however, some O-glycoproteins are not produced efficiently in CHO. We have previously shown that the capacity for O-glycosylation of proteins can be one limiting parameter for production of active proteins in CHO.

Engineering Chinese hamster ovary (CHO) cells for producing recombinant proteins with simple glycoforms by zinc-finger nuclease (ZFN)-mediated gene knockout of mannosyl (alpha-1,3-)-glycoprotein beta-1,2-N-acetylglucosaminyltransferase (Mgat1).

While complex N-linked glycoforms are often desired in biotherapeutic protein production, proteins with simple, homogeneous glycan structure have implications for X-ray crystallography and for recombinant therapeutics targeted to the mannose receptor of antigen presenting cells. Mannosyl (alpha-1,3-)-glycoprotein beta-1,2-N-acetylglucosaminyltransferase (Mgat1, also called GnTI) adds N-acetylglucosamine to the Man5GlcNAc2 (Man5) N-glycan structure as part of complex N-glycan synthesis. Here, we report the use of zinc-finger nuclease (ZFN) genome editing technology to create Mgat1 disrupted Chinese hamster ovary (CHO) cell lines.