Increased synthesis of GFAP by TCDD in differentiation-disrupted SFME cells

The effects of 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) on gene expression and synthesis of glial fibrillary acidic protein (GFAP) in differentiation-disrupted serum-free mouse embryo (SFME) cells were examined. SFME cells were exposed to fetal calf serum (FCS) and dimethyl sulfoxide (DMSO) to induce differentiation and increase GFAP synthesis. Disruption of differentiation was caused by low-level toluene, significantly inhibiting GFAP synthesis. TCDD at 0.01, 0.1 and 1 pg/ml in the presence of low-level toluene increased GFAP synthesis in the SFME cells, while expression of GFAP mRNA showed no significant change. The TCDD-treated SFME cells detached from the culture substratum, indicating an apparent change in cell adhesion. These results suggest that low-level TCDD further disrupts differentiation of SFME cells in the presence of low-level toluene by upregulating GFAP synthesis and by altering the ability in cell adhesion and that GFAP synthesis is not disrupted at transcription but at translation.