ABSTRACT
Serum-free mouse embryo (SFME) cells derived in a defined serum-free medium have been cultured for more than 200 generations and display properties of neural progenitor cells. SFME cells express the neuroepithelial stem cell marker nestin in defined serum-free medium. Exposure of SFME cells to transforming growth factor beta (TGF-beta) or serum decreases nestin expression and induces the astrocyte marker glial fibrillary acidic protein, suggesting that SFME cells differentiate into astrocytes upon exposure to TGF-beta or serum. We examined the expression by SFME cells of the functional central nervous system (CNS) astrocyte marker glutamine synthetase (GS). GS activity is induced in SFME cells upon exposure to TFG-beta or serum. The induction of GS activity was dose- and time-dependent and was reversible. Retinoic acid, hydrocortisone, and dibutyryl cyclic AMP also induced GS expression. The induction of GS activity was accompanied by an increase in the level of GS mRNA and protein. This work provides further evidence that SFME cells represent neural progenitor cells which differentiate into functional astrocytes upon exposure to TGF-beta or serum.
Subject(s)
Astrocytes/cytology , Brain/embryology , Gene Expression Regulation, Developmental , Glutamate-Ammonia Ligase/biosynthesis , Nerve Tissue Proteins/biosynthesis , Stem Cells/cytology , Animals , Astrocytes/enzymology , Biomarkers , Blood , Blotting, Western , Brain/cytology , Bucladesine/pharmacology , Cattle , Cell Differentiation/drug effects , Charcoal , Culture Media, Serum-Free/pharmacology , Enzyme Induction/drug effects , Glutamate-Ammonia Ligase/genetics , Hydrocortisone/pharmacology , Intermediate Filament Proteins/biosynthesis , Intermediate Filament Proteins/genetics , Mice , Mice, Inbred BALB C , Nerve Tissue Proteins/genetics , Nestin , Stem Cells/drug effects , Stem Cells/enzymology , Transforming Growth Factor beta/pharmacology , Tretinoin/pharmacology , Valproic Acid/pharmacologyABSTRACT
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.
