Serum-free mouse embryo cells generate a self-sustaining feedback loop for an astrocyte marker protein and respond to cytokines and bisphenol A in accordance with the subtle difference in their differentiation state

Serum-free mouse embryo (SFME) cells, the astrocyte progenitor cells in the central nervous system, generated a self-sustaining feedback loop for glial fibrillary acidic protein (GFAP) expression after a period of cell passages. The period required was about 150 days (30 passages). SFME and high-GFAP-expressing SFME (G-SFME) cells were exposed to 10 ng/ml leukemia inhibitory factor (LIF) and 10 ng/ml bone morphogenetic protein 2 (BMP2) to induce differentiation and their responses to cytokine signals were analyzed. Although differentiation was significantly induced in both cell types, SFME cells showed more obvious responses to the cytokine signals. Various concentrations of bisphenol A (BPA) (0.1 pg/ml to 1 μg/ml) were added to determine its effects on cell differentiation. A completely serum-free culture was developed for effective differentiation of G-SFME cells with LIF and BMP2, and GFAP expression was significantly increased in the presence of 1-100 pg/ml BPA. These increases were attributed to excessive activation of signal transducer and activator of transcription 3 (STAT3) and mothers against decapentaplegic homolog 1 (Smad1) by the low-level BPA. The data obtained in the present study revealed that the sensitivity of the cells to LIF, BMP2 and BPA could change upon cell differentiation, suggesting that the cells may possibly respond differently to cytokines and endocrine disruptors depending on subtle differences in their differentiation state.