COS Cells 

 COS cells are monkey kidney fibroblasts (Fig. 1); they have become popular in recent years because they support certain strains of replication-deficient animal viruses (1, 2) and can be transfected easily (3, 4). Two lines are in common use, COS-7 (ATCC CRL-1651) and COS-1 (ATCC CRL-1650). 

Figure 1. Confluent culture of COS-7 cells. Phase contrast, Olympus CK microscope, 20× objective.

1. Origin

 Both cell lines were derived from CV-1 cells (ATCC CCL-70), an established cell line of simian fibroblasts, by transformation with an origin-defective mutant of SV40 virus (1). Both are T-antigen-positive, permit lytic growth of SV40, and support the replication of temperature-sensitive mutant SV40 tsA209 and of SV40 mutants with deletions in the early region. COS-1 cells contain a single integrated copy of the complete early region of the SV40 genome.

2. Properties

 COS cells are propagated as a monolayer in the alpha modification of Eagle's minimal essential medium (a-MEM) supplemented with 10% fetal bovine serum  or in Dulbecco's modification of Eagle's medium. They grow rapidly, with an approximate population doubling time of 18 h.

3. Usage

 COS cells have been used extensively in DNA transfer studies (5-7) and have been transfected by a number of different methods, including calcium phosphate (8), DEAE (4), and lipid transfection (9).

References

1. Y. Gluzman (1981) SV40-transformed simian cells support the replication of early SV40 mutants. Cell 23, 175–182. 

2.F. Unckell, R. E. Streeck, and M. Sapp (1997) J. Virol. 71, 2934–2939.

3. Y. Cao, D. M. Stafforini, G. A. Zimmerman, T. M. McIntyre, and S. M. Prescott (1997) J. Biol. Chem. 273, 4012–4020. 

4. J. J. Schwartz and R. Rosenberg (1998) in DNA Transfer to Cultured Cells, K. Ravid and R. I. Freshney, eds., Wiley-Liss, New York, pp. 179–192. 

5. V. Misra, H. J. Klamut, and A. M. Rauth (1998) Transfection of COS-1 cells with DT-diaphorase cDNA: Role of base change at position 609. Br. J. Cancer 77, 1236–1240. 

6. S. G. Plonk, S. K. Park, and J. H. Exton (1998) J. Biol. Chem. 273, 4823–4826. 

7. B. Corsi, F. Perrone, M. Bourgeois, C. Beaumont, M. C. Panzeri, A. Cozzi, R. Sangregorio, P. Santambrogio, A. Albertini, P. Arosio, and S. Levi (1998) Biochem. J. 330, 315–320. 

8. J. V. O''Mahoney and T. E. Adams (1998) in DNA Transfer to Cultured Cells, K. Ravid and R. I. Freshney, eds., Wiley-Liss, New York, pp. 125–145. 

9 .V. V. Bickko (1998) In DNA Transfer to Cultured Cells (K. Ravid and R. I. Freshney, eds., Wiley-Liss, New York, pp. 193–212.