Research from Russian Academy of Sciences Yields New Findings on Biotechnology (Improved elongation factor-1 alpha-based vectors for stable high-level expression of heterologous proteins in Chinese hamster ovary cells)
By a News Reporter-Staff News Editor at Biotech Week -- Investigators discuss new findings in Technology. According to news reporting originating in Moscow, Russia, by NewsRx journalists, research stated, "Establishing highly productive clonal cell lines with constant productivity over 2-3 months of continuous culture remains a tedious task requiring the screening of tens of thousands of clonal colonies. In addition, long-term cultivation of many candidate lines derived in the absence of drug selection pressure is necessary."
The news reporters obtained a quote from the research from the Russian Academy of Sciences, "Expression vectors based on the elongation factor-1 alpha (EEF1A) gene and the dihydrofolate reductase (DHFR) selection marker (with separate promoters) can be used to obtain highly productive populations of stably transfected cells in the selection medium, but they have not been tested for their ability to support target gene amplification under gradually increasing methotrexate pressure. We have modified EEF1A-based vectors by linking the DHFR selection marker to the target gene in the bicistronic RNA, shortening the overall plasmid size, and adding an Epstein-Barr virus terminal repeat fragment (EBVTR) element. Presence of the EBVTR element increased the rate of stable transfection by the plasmid by 24 times that of the EBVTR-minus control and improved the rate of methotrexate-driven gene amplification. The mean expression level of the enhanced green fluorescent protein (eGFP) used herein as a model protein, increased up to eight-fold using a single round of amplification in the case of adherent colonies formation and up to 4.5-fold in the case of suspension polyclonal cultures. Several eGFP-expressing cell populations produced using vectors with antibiotic resistance markers instead of the DHFR marker were compared with each other. Stable transfection of Chinese hamster ovary (CHO) DG44 cells by the p1.2-Hygro-eGFP plasmid (containing a hygromycin resistance marker) generated highest eGFP expression levels of up to 8.9% of the total cytoplasmic protein, with less than 5% of the cell population being eGFP-negative. The p1.1 vector was very effective for stable transfection of CHO cells and capable of rapid MTX-driven target gene amplification, while p1.2-Hygro achieved similar eGFP expression levels as p1.1."
According to the news reporters, the research concluded: "The set of vectors we have developed should speed-up the process of generating highly productive clonal cell lines while substantially decreasing the associated experimental effort."
For more information on this research see: Improved elongation factor-1 alpha-based vectors for stable high-level expression of heterologous proteins in Chinese hamster ovary cells. Bmc Biotechnology, 2014;14():56. (BioMed Central - www.biomedcentral.com/; Bmc Biotechnology - www.biomedcentral.com/bmcbiotechnol/)
Our news correspondents report that additional information may be obtained by contacting N.A. Orlova, Laboratory of Mammalian Cell Bioengineering, Centre Bioengineering, Russian Academy of Sciences, 60-letija Oktyabrya 7, Moscow 117312, Russia. Additional authors for this research include S.V. Kovnir, J.A. Hodak, I.I. Vorobiev, A.G. Gabibov and K.G Skryabin (see also Technology).
Keywords for this news article include: Moscow, Russia, Eurasia, Technology.
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