Abstract
The murine embryonal carcinoma cell line P19S18O1A1 develops into neuronlike cells after treatment with retinoic acid (Edwards and McBurney, 1983). We have analyzed the expression of cell surface carbohydrate antigens and intracellular cytoskeletal antigens in differentiating O1A1 cells in order to identify the cell types present in the cultures and to characterize the differentiation process. Undifferentiated O1A1 cells express the SSEA-1 antigen, GD3 ganglioside, and the D1.1 ganglioside antigen, carbohydrate markers that are found on early embryonic cells and neuroepithelial germinal cells in vivo. The cells also bind tetanus toxin, cholera toxin, and monoclonal antibody A2B5, probes that bind to gangliosides found on the surfaces of neurons and immature astrocytes in vivo and in vitro. They contain vimentin-type intermediate filament antigens but have no detectable neurofilament or glial filament protein antigens. After aggregation of the cells in medium containing retinoic acid followed by growth in a serum-free chemically defined medium, over 80% of the cells differentiate into neurons as determined by immunofluorescent labeling with antibodies against neurofilament protein antigens. The differentiated cells no longer express either the embryonic or neuroepithelial carbohydrate antigens, but they continue to express the cell surface markers characteristic of neurons. These changes in the expression of cell surface antigens are accompanied by changes in ganglioside metabolism, including a shift towards the synthesis of more complex gangliosides. Thus, the retinoic acid-induced changes in O1A1 cells in vitro resemble the in vivo development of neurons. This establishes the O1A1 cell line as a relevant model system for studies of the molecular basis of neuronal differentiation and development.
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