ESTABLISHMENT AND CHARACTERISTICS OF A PRACTICAL AND USEFUL ASTROCYTECELL-LINE TRANSFORMED BY A TEMPERATURE-SENSITIVE MUTANT OF SIMIAN-VIRUS-40

A practical mouse astrocyte cell line (A640-IG) was established by tra nsformation with a temperature-sensitive mutant of simian virus 40 (SV 40) and the relationship between the function of SV40 large T antigen and the growth and differentiation of A640-IG cells, which are most cl early dependent on temperature that ever established, was reported. A6 40-IG cells proliferated actively with expression of large T antigen w hen they were cultured at 33 degrees C. They had a fibroblast-like app earance, and displayed faint immunoreactivity with an antibody against glial fibrillary acidic protein (GFAP). However, when large T antigen expression ceased at 39 degrees C, the cells did not grow actively an d differentiated into astrocytes as demonstrated by both their morphol ogical and immunohistochemical characteristics. Differentiation into a strocytes was more obvious when the cells were plated on bacteriologic al dishes in high density. Western blotting confirmed immunohistochemi cal observations. A640-IG cells thus showed contrasting behaviour in t erms of cell growth and differentiation depending on the temperature. This unique and practical astrocyte cell line is a useful model for in vestigating the mechanisms of astrocyte growth and differentiation.