Regulated expression at high copy number allows production of a growth-inhibitory oncogene product in Drosophila Schneider cells.

Abstract

The Drosophila metallothionein promoter (Mtn) was used to obtain efficient, regulated expression of foreign gene products inserted in high copy numbers into Drosophila melanogaster Schneider 2 cells. An expression unit comprised of a reporter gene [Escherichia coli galactokinase (ga/K)] fused to the Mtn promoter was stably introduced into Schneider 2 cells in up to several hundred copies per cell in a single transfection-selection event. This system contrasts dramatically with other eukaryotic systems that permit only a few copies of a gene to be stably inserted in a single transfection-selection event. The transfected Drosophila $2 cell lines expressed high levels of both ga/K mRNA and protein in response to metal induction. Most important, and in contrast to mammalian cells, expression remained fully regulated even at high copy number, with low basal expression maintained in the absence of inducer. This regulated system was used to obtain efficient expression in Drosophila cells of an otherwise lethal or growth-inhibitory gene product, the human H-ras oncogene. The ability to obtain regulated high-level expression of potentially lethal foreign proteins is unique to the Drosophila cell system.

Expression, characterization, and preliminary X-ray crystallographic analysis of recombinant murine Follistatin-like 1 expressed in Drosophila S2 cells

“…Expression of recombinant proteins in insect cell hosts is advantageous because it permits production of posttranslationally modified eukaryotic proteins in large amounts and in a relatively short period of time. Moreover, in the present Drosophila S2 expression system, the pMT/BiP-HisA expression vector contained the metallothionein (MT) promoter, which allowed for high levels of FSTL1 expression when induced by copper sulfate (CuSO 4 ) (35). In addition to the MT promoter, the vector also contained a BiP secretion signal, which promoted secretion of FSTL1 containing proper posttranslational modifications, such as glycosylation (36).…”

Preparation and immunogenic properties of a recombinant West Nile subunit vaccine

“…Expression of recombinant proteins-The West Nile envelope protein (E) and non-structural protein 1 (NS1) were produced in the Drosophila S2 expression system. The expression system consists of the Drosophila S2 cells and a series of broad host plasmid vectors that directed the expression of heterologous proteins [32][33][34]. The expression plasmid pMttbns (derived from pMttPA) contained the following elements: Drosophila melanogaster metallothionein promoter, the human tissue plasminogen activator secretion leader (tPAL) and the SV40 early polyadenylation signal.…”

Human T-Cell Leukemia Virus Type 1 Receptor Expression among Syncytium-Resistant Cell Lines Revealed by a Novel Surface Glycoprotein-Immunoadhesin

“…D. melanogaster Schnieder 2 cells were maintained in Shields and Sang M3 medium supplemented with 10% fetal bovine serum (Gibco-BRL) (24). Cotransfection of cells with plasmid DNA and the selection vector pCOhygro and subsequent isolation of stable cell lines by the hygromycin B selection procedure have been described previously (3,24).…”