Neurotrophic protein S100 beta stimulates glial cell proliferation.

Nervous system development involves a coordinated series of events, including regulation of cell proliferation and differentiation by specific extracellular factors. S100 beta is a neurotrophic protein that has been implicated in regulation of cellular proliferation, but direct evidence was lacking. In this report, nanomolar concentrations of S100 beta are shown to stimulate proliferation of rat C6 glioma cells and primary astrocytes. An S100 mutant with a single amino acid change was inactive. S100 beta also stimulated increases in the steady-state levels of c-myc and c-fos protooncogene mRNAs and complemented the effects of platelet-derived growth factor. Two neuroblastoma cell lines did not proliferate in response to S100 beta, suggesting that the mitogenic activity of S100 beta is selective for astroglial cells. These results suggest that S100 beta may be involved in the coordinate development and maintenance of the central nervous system by synchronously stimulating the differentiation of neurons and the proliferation of astroglia.