Immunocytochemical and functional characterization of an immortalized type 1 astrocytic cell line

The DI TNC1 cell line has been derived from cultures of rat brain astrocytes by targeted oncogenesis. Cultured astrocytes are known to promote neurite outgrowth via the production of adhesion molecules found either on the cell surface or in the extracellular matrix. We sought to investigate whether DI TNC1 cells retained the ability to produce such neurite-inducing molecules, and promote neurite growth. We found by immunofluorescence that DI TNC1 cells expressed laminin, N-CAM and 1A1. The latter is a cell adhesion molecule that is expressed exclusively on astrocytes of the type 1 lineage. In vitro neurite outgrowth assays were also used to assess the functional properties of these cells. Monolayers of DI TNC1 cells were almost as effective a substrate as monolayers of astrocytes purified from the neonatal rat brain in their ability to support neurite outgrowth. In addition, PC12 cells grown on extracellular matrix derived from either DI TNC1 cells or neonatal astrocytes displayed significantly more neurite growth than cells plated on plastic. This effect was partially inhibited by preincubation of the extracellular matrix with anti-laminin antibodies. Taken together, these results suggest that the immortalized DI TNC1 cells show many similarities to neonatal astrocytes. Given the heterogeneity of cultured astrocytes, this homogeneous cell line may prove to be particularly useful for future investigations on interactions between glia and neurons.