Changing subcellular distribution and activity-dependent utilization of a dendritically localized mRNA in developing Purkinje cells

In cerebellar Purkinje neurons, the degree of dendritic segregation of the Purkinje cell-specific mRNA L7/pcp-2 is correlated with their development a nd synaptic investment. This developmental pattern is also observed in Purk inje cells in primary dissociated culture. Short-term (12-48 h) stimulation of cultured Purkinje cells by potassium-induced depolarization or blockade of their inhibitory GABAergic input results in an increased incidence of P urkinje cells with L7/pcp-2 mRNA-positive dendrites and increased levels of L7 protein expression, the latter by a posttranscriptional mechanism. None of these treatments affected the localization of the mRNA encoding calbind in D28k nor the level of this protein in Purkinje neurons. Protracted expos ure to depolarizing levels of potassium or elimination of GABAergic transmi ssion resulted in conspicuous changes of Purkinje cell dendritic morphology . These data suggest a scenario in which activity-driven translation of sub cellularly segregated mRNAs may contribute to the developmental and functio nal plasticity of nerve cells.