Translation cell culture

MammaBan. For mammalian proteins, mammalian cells offer the most natural host for expression. Problems of incorrect processing and post-translational modification are avoided using these cells. Mammalian cells are usually grown in continuous cell culture, reducing the variabiUty in results (see Cell CULTURE technology). Moderate-level production of native protein is possible. The procedure, however, is slow and very cosdy, and the level of protein expression is low. Thus large-scale production of proteins in mammalian cells is not practical. When low quantities of protein are sufficient, this system offers the several advantages described. 

Characterization of the exact nature of the post-translational modifications the mammary system is capable of undertaking. For example, the carbohydrate composition of tPA produced in this system differs from the recombinant enzyme produced in murine cell culture systems. 

Mammalian cell culture is more technically complex and more expensive than microbial cell fermentation. Therefore, it is usually only used in the manufacture of therapeutic proteins that show extensive and essential post-translational modifications. In practice, this usually refers to glycosylation, and the use of animal cell culture would be appropriate where the carbohydrate content and pattern are essential to the protein s biological activity, its stability or serum half-life. Therapeutic proteins falling into this category include EPO (Chapter 10), the gonadotrophins (Chapter 11), some cytokines (Chapters 8-10) and intact monoclonal antibodies (Chapter 13). 

The vast majority of research focused on selenium in biology (primarily in the fields of molecular biology, cell biology, and biochemistry) over the past 20 years has centered on identification and characterization of specific selenoproteins, or proteins that contain selenium in the form of selenocysteine. In addition, studies to determine the unique machinery necessary for incorporation of a nonstandard amino acid (L-selenocysteine) during translation also have been central to our understanding of how cells can utilize this metalloid. This process has been studied in bacterial models (primarily Escherichia colt) and more recently in mammals in vitro cell culture and animal models). In this work, we will review the biosynthesis of selenoproteins in bacterial systems, and only briefly review what is currently known about parallel pathways in mammals, since a comprehensive review in this area has been recently published. Moreover, we summarize the global picture of the nonspecific and specific use of selenium from a broader perspective, one that includes lesser known pathways for selenium utilization into modified nucleosides in tRNA and a labile selenium cofactor. We also review recent research on newly identified mammalian selenoproteins and discuss their role in mammalian cell biology. 

Gold, R, Schmied, M., Rothe, G, Zischler, H., Breitschopf, H, Wekerle, H, and Lassmann, H, (1993) Detection of DNA fragmentation in apoptosis- application of in situ nick translation to cell culture systems and tissue sections J Histochem Cytochem 41, 1023-1030... 

One feature of the hydroxypyranones that presented a major challenge was the poor translation of high intrinsic inhibitory potency against the enzyme into antiviral activity in cell culture (Prasad et al., 1996). The acidic character of the enolic hydroxy group (pAa 4.2-6.5) as compared with aliphatic hydroxyl groups found in other classes of inhibitors did not appear to offer an explanation in as much as inhibitors of the pyranone class penetrate cells efficiently (Vara Prasad et al, 1995). Empirically,... 

Mammalian cell culture is a technology used for the production of recombinant proteins of therapeutic use, as they can secrete proteins with post-translational modifications similar to those present in human proteins. The most important advantages of this capacity of the mammalian cell lines are that they secrete a protein with the similar characteristics to the original protein, so that the protein can be used for human treatment without generating immunological responses. 

This chapter describes some of the most important and well-studied forms of post-translational modifications of proteins, which have been associated with the production of glycoproteins as biopharmaceuticals from mammalian cell culture systems. Most attention is given to glycosylation because of its general importance for the activity of all these... 

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