1,25-dfflydroxyvitamin d₃ induces differentiation of rat neuroblastoma cells

Receptors for 1,25-dihydroxyvitamin D, (l,25(OH)₂D₃) are present in developing dorsal root ganglia in vivo and in dorsal root ganglion cells maintained in culture (J. A. Johnson, Brain Research, in press, 1996). To investigate the function of 1,25(OH)₂D₃ in the development of neuronal cells we treated a rat neuroblastoma cell line, NE-115, with ethanol, 10^-12 M, Kr'°M, and Iff'M 1,25(OH)₂D₂. As a control serum-deprivation, a manoever known to induce differentiation in these cells, was carried out over a six day period. A significant decrease in cell growth proportional to the amount of 1,25(OH)2D3 added was observed within 24 hours. Following treatment with l,25(OH)2Dj a greater percentage of the cells underwent morphological changes characteristic of a more mature phenotype. To determine if the decrease in cell growth and change in morphology was associated with cell differentiation, we tested the cells for the production of tau-1, a protein marker of neuronal differentiation. Cells were treated over a 3 day period with ethanol, 11^-12M, 10-'°M, and Iff'M 1,25(OH)₂D₃ and also serum deprived. Cells were subsequently stained on a daily basis using an antitau-1 monoclonal antibody. A significant increase in the amount of tau-1 protein was observed in cells that had been treated with 1,25(OH)₂D,. Ethanol treated cells showed only modest changes in tau-1 protein. These results suggest that l,25(OH)₂D₃, is a prodifferentiation factor for NE-115 cells and may play an important role in the development of neuronal cells.