S100-BETA STIMULATES CALCIUM FLUXES IN GLIAL AND NEURONAL CELLS

The glial-derived protein S-100-beta can act as a mitogen or a neurotrophic factor, stimulating proliferation of glial cells or differentiation of immature neurons. We report here that dimeric S100-beta evokes increases in intracellular free calcium concentrations ([Ca2+]i) in both glial cells and neuronal cells. The [Ca2+]i increase exhibited a rapid transient component which was not affected by removal of extracellular calcium and a sustained component which appeared to require influx of extracellular calcium through Ni2+-sensitive channels. S100-beta also stimulated hydrolysis of phosphoinositides, suggesting a mobilization of calcium from intracellular stores. These data suggest that although the final biological responses of neuronal and glial cells to S100-beta are different, transduction of the S100-beta signal in both cell types involves changes in [Ca2+]i.