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 C NS progenitor cells we investigated the expression of the gene encodin g nestin, an intermediate filament protein expressed by neuroepithelia l stem cells of the CNS. SFME cells express nestin in serum-free mediu m, and nestin expression is reversibly down-regulated by TGF-beta or s erum. These results demonstrate that nestin expression is regulated by factors present in serum and support the hypothesis that SFME cells r epresent a CNS progenitor cell.