title: Toxin-antitoxin based transgene expression in mammalian cells.
abstract: Long-term, recombinant gene expression in mammalian cells depends on the nature of the transgene integration site and its inherent properties to modulate transcription (epigenetic effects). Here we describe a method by which high transgene expression is achieved and stabilized in extensively proliferating cultures. The method is based on strict co-expression of the transgene with an antitoxin in cells that express the respective toxin. Since the strength of antitoxin expression correlates with an advantage for cell growth, the cells with strong antitoxin expression are enriched over time in cultures of heterogeneous cells. This principle was applied to CHO cell lines that conditionally express the toxin kid and that are transduced to co-express the antitoxin kis together with different transgenes of interest. Cultivation of pools of transfectants that express the toxin steadily increase their transgene expression within several weeks to reach a maximum that is up to 120-fold over the initial status. In contrast, average transgene expression drops in the absence of toxin expression. Together, we show that cells conditionally expressing kid can be employed to create overexpressing cells by a simple coupling of kis to the transgene of interest, without further manipulation and in absence of selectable drugs.
authors.affiliation: Helmholtz Centre for Infection Research, Braunschweig, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Nehlsen
authors.forename: S
authors.initials: S
authors.lastname: Herrmann
authors.forename: J
authors.initials: J
authors.lastname: Zauers
authors.forename: H
authors.initials: H
authors.lastname: Hauser
authors.forename: D
authors.initials: D
authors.lastname: Wirth
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D019076:Transgenes
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C068354:Kis protein, Bacteria; D012333:RNA, Messenger; C485184:enhanced green fluorescent protein; C473072:kid toxin protein, E coli plasmid R1; D049452:Green Fluorescent Proteins