Low levels of aflatoxin B1, ricin, and milk enhance recombinant protein production in mammalian cells.
Gene expression in transduced mammalian cells correlates with virus titer, but high doses of vector for gene therapy leads to toxicity in humans and in animals. Changing the optimal tissue culture medium by adding low levels of environmental stressors, such as 1 µM of the fungal toxin aflatoxin B1 (AFB1), 1 ng of the castor bean protein toxin ricin, or 1% reconstituted milk, enhances transcription and increases production of proteins in transduced mammalian cells as demonstrated by production of the following three recombinant proteins: firefly luciferase, β-galactosidase, and green fluorescent protein (GFP). Higher concentrations of the stress-producing substances damage the cells beyond recovery, resulting in inhibited gene expression and cell death. We also evaluated the effect of the stressor substances on the enhanced infectivity of virus. The presented findings extend methods for large-scale transient recombinant protein production in mammalian cells and suggest that it may be possible to reduce the cytotoxicity of the adenovirus by reducing the virus titer without adversely affecting gene expression levels.
Foodborne Contaminants, Agricultural Research Service, United State Department of Agriculture, Albany, California, United State of America. reuven.rasooly@ars.usda.gov
Reuven
R
Rasooly
Bradley
B
Hernlem
Mendel
M
Friedman
D016604:Aflatoxin B1 / Q000494:pharmacology*; D000818:Animals; D002522:Chlorocebus aethiops; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation / Q000187:drug effects*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008322:Mammals; D008892:Milk / Q000502:physiology*; D011994:Recombinant Proteins / Q000235:genetics* / Q000378:metabolism*; D012276:Ricin / Q000494:pharmacology*; D014709:Vero Cells; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
D011994:Recombinant Proteins; D049452:Green Fluorescent Proteins; D012276:Ricin; D016604:Aflatoxin B1; D001616:beta-Galactosidase