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

Purkinje cells establish a glutamatergic synapse with the parallel fibers i n the cerebellum. Bergmann glial cells surround this synapse. The transcrip tion factor Stat3, highly expressed in cerebellum, is present in cultures o f chick Bergmann glia. Treatment of these cells with L-glutamate induces th e tyrosine-phosphorylation of Stat3. The maximal phosphorylation was observ ed after 15 min and by 30 min returned to basal levels. This effect correla ted with Stat3 translocation to nucleus and the appearance of a retarded ba nd in gel mobility shift assays. The effects observed with L-glutamate were mediated through metabotropic glutamate receptors. These results further s upport the notion that glial cells respond to L-glutamate through changes i n the existing proteins and also in gene expression regulation.