Down regulation of nestin by TGF-beta or serum in SFME cells accompanies differentiation into astrocytes.

The serum-free mouse embryo (SFME) cell line, derived from 16-day-old mouse embryos in medium in which serum was replaced by growth factors and other supplements, has been cultured for more than 200 generations. SFME cells are nontumorigenic, lack gross chromosomal abnormalities, and display characteristics of CNS progenitor cells. SFME cells show reversible induction of the astrocyte-specific marker glial fibrillary acidic protein when cultured in the presence of TGF-beta or serum. In order to determine if SFME cells exhibit further characteristics of CNS progenitor cells we investigated the expression of the gene encoding nestin, an intermediate filament protein expressed by neuroepithelial stem cells of the CNS. SFME cells express nestin in serum-free medium, and nestin expression is reversibly down-regulated by TGF-beta or serum. These results demonstrate that nestin expression is regulated by factors present in serum and support the hypothesis that SFME cells represent a CNS progenitor cell.