| Serum-free mouse embryo (SFME) cells are derived in medium in which serum is replaced with growth factors and other supplements. They display unusual properties. They do not lose proliferative potential or show gross chromosomal aberration upon extended culture, they depend on epidermal growth factor (EGF) for survival, and are reversibly growth inhibited by plasma and serum. In the presence of transforming growth factor beta (TGF-{dollar}beta{dollar}) SFME cells express the astrocyte marker, glial fibrillary acidic protein (GFAP).; The growth inhibitory activity of human plasma on serum-free mouse embryo cells was investigated. Human plasma did not inhibit SFME cells transformed with the human Ha-ras oncogene. The activity was present in delipidated plasma and was not dialyzable against 1 M acetic acid. The activity could be precipitated by methanol, bound to concanavalin A-agarose and was retarded by Sephadex G-50 in 200 mM acetic acid. A fifty to hundred fold purification was achieved, although the differential inhibition of untransformed versus transformed cells was lost in the course of the purification.; Using the technique of differential screening of a cDNA library a calf serum- and TGF-{dollar}beta{dollar}-regulated mRNA species was identified in SFME cells. This mRNA was approximately 8.5 kilobases in size and brain-specific. Picomolar quantities of TGF-{dollar}beta{dollar} caused an increase of this message in SFME cells within four hours. This increase was reversed when TGF-{dollar}beta{dollar} was removed from the culture medium. |
