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Transformed African Green Monkey Kidney Fibroblast Cells (COS-7 Line)

The CV-1 cell line, which is permissive for lytic growth of simian virus 40 (SV40), was established in the 1960s from the kidney of an African green monkey. The COS-7 line was developed from that line about 20 years later by Yakov Gluzman via transformation with an origin defective mutant of SV40 that codes for the wild-type virus T-antigen.

COS-7 Cells

Adherent growth to both glass and plastic surfaces is characteristic of COS-7 cells in culture. The line, which is often utilized as a transfection host, retains the CV-1 trait of complete permissiveness for the lytic growth of SV40 and supports the replication of the tsA209 strain of the virus at 40 degrees Celsius as well as SV40 mutants with deletions in the early region. COS-7 cells are a popular research tool, especially for transfection experiments with recombinant plasmids.

Studies involving SV40 have been intense over the last few decades, partly due to the potential link between the virus and some varieties of cancer that affect humans, such as mesothelioma. SV40 is also of interest because the genetic organization of the DNA tumor virus is unusually simple, facilitating its comparatively easy genetic manipulation. SV40 DNA is 5243 nucleotides long and is arranged in a closed circular superhelical conformation. Only a few functions are encoded by the viral DNA because of space limitations, and capsid proteins are encoded with overlapping reading frames. Besides capsid proteins, the potentially oncogenic protein dubbed T-antigen and a spliced form of the material known as small t-antigen are encoded by SV40 DNA. T-antigen typically controls SV40 DNA replication and packaging of the virus in simian cells. In a variety of other cell types, however, T-antigen becomes bound to certain proteins involved in the regulation of cell growth, which can interfere with their customary functions and lead to tumor growth.

A monolayer culture of African green monkey kidney cells (presented above) was labeled with a mitochondrion-selective stain, MitoTracker Deep Red 633 (pseudocolored blue), and a high-affinity nucleic acid stain, SYTOX Orange. In addition, the filamentous actin network was targeted with BODIPY FL conjugated to phallacidin (a toxin derived from the death cap mushroom). Images were recorded with a 60x oil immersion objective using a zoom factor of 2.0 and sequential scanning with the 488-nanometer spectral line of an argon-ion laser, the 543-nanometer line from a green helium-neon laser, and the 633-nanometer line of a red helium-neon laser. During the processing stage, individual image channels were pseudocolored with RGB values corresponding to each of the fluorophore emission spectral profiles unless otherwise noted above.

Additional Confocal Images of African Green Monkey Kidney Fibroblast (COS-7) Cells

Mitochondria, Actin, and DNA Distribution in COS-7 Fibroblasts - The filamentous actin and mitochondrial networks were targeted in an adherent culture of COS-7 kidney cells with BODIPY FL conjugated to phallacidin and MitoTracker Orange CMTMRos, respectively. DNA in the cells was counterstained with the red-absorbing dye TO-PRO-3 (pseudocolored cyan).

Targeting F-Actin in African Green Monkey Kidney Cell Cultures with Phallotoxins - The culture of COS-7 kidney cells presented in this section was labeled for mitochondria with MitoTracker Orange CMTMRos and for the cytoskeletal filamentous actin network with BODIPY FL conjugated to phallacidin, a cyclic peptide derived from a toxic mushroom (Amanita phalloides). In addition, the cells were probed for DNA in the cell nucleus with TO-PRO-3, a monomeric cyanine nucleic acid stain.

COS-7 Cells with BODIPY FL, MitoTracker Deep Red 633, and SYTOX Orange - A COS-7 fibroblast cell culture was stained with BODIPY FL conjugated to phallacidin, targeting the F-actin cytoskeletal network. The cells were also stained with MitoTracker Deep Red 633 (pseudocolored magenta) and SYTOX Orange (pseudocolored red), which preferentially bind with intracellular mitochondria and DNA in the cell nucleus, respectively.

Contributing Authors

Nathan S. Claxton, Shannon H. Neaves, and Michael W. Davidson - National High Magnetic Field Laboratory, 1800 East Paul Dirac Dr., The Florida State University, Tallahassee, Florida, 32310.