Stat3 participates in the metabotropic glutamate signaling pathway in Bergmann glial cells

Purkinje cells establish a glutamatergic synapse with the parallel fibers in the cerebellum. Bergmann glial cells surround this synapse. The transcription factor Stat3, highly expressed in cerebellum, is present in cultures of chick Bergmann glia. Treatment of these cells with L-glutamate induces the tyrosine-phosphorylation of Stat3. The maximal phosphorylation was observed after 15 min and by 30 min returned to basal levels. This effect correlated with Stat3 translocation to nucleus and the appearance of a retarded band in gel mobility shift assays. The effects observed with L-glutamate were mediated through metabotropic glutamate receptors. These results further support the notion that glial cells respond to L-glutamate through changes in the existing proteins and also in gene expression regulation.