Differentiation-specific mRNA expression of a mouse bipotential glial cell line.

We have previously reported that a bipotential glial cell line from mouse cerebrum, designated OS3, phenotypically differentiates into oligodendrocytes and astrocytes both in vitro and in vivo. To study the potential mechanisms of differentiation, in this study we investigated mRNA expression of cytokines and developmentally regulated proteins in OS3 during differentiation into oligodendrocytes by semi-quantitative reverse transcription and polymerase chain reaction. In the presence of 10% calf serum OS3 cells expressed IL-1alpha and IL-1beta mRNA. However, when the cells were cultured in chemically defined medium or low serum-containing medium the expression of IL-1alpha and IL-1beta mRNA was down-regulated. Under stimulation of phorbol ester, expression of IL-6 and nerve growth factor mRNA was up-regulated. The capacity for differentiation of OS3 cells into oligodendrocytes in vitro was limited and most OS3 cells ceased their differentiation at the proligodendroblast stage. However, expression of proteolipid protein (PLP) and DM20 mRNA was detectable and was up-regulated in accordance with the differentiation into oligodendrocytes. As a control, primary astrocytes expressed DM20 mRNA but not PLP mRNA and the expression of DM20 mRNA was independent of culture condition. Therefore, OS3 cells will be of use for the study of differentiation of progenitor cells into type-2 astrocytes or oligodendrocytes at the molecular level.