DIFFERENTIAL EXPRESSION OF PROTEIN-KINASES IN CULTURED PRIMARY NEURONS DERIVED FROM THE CEREBRAL-CORTEX, HIPPOCAMPUS, AND SYMPATHETIC-GANGLIA

Protein kinases play pivotal roles in the development of the nervous s ystem. They are involved in almost every stage of neuronal development , from initial proliferation and differentiation of progenitor cells t o pathfinding of neurites and formation of synapses. Activation of pro tein kinases is also critical for neuronal cell, survival. To gain fur ther insights into kinases in neural development, we studied the expre ssion patterns of protein kinases in three cultured primary neurons by degenerate primer-based reverse transcription-polymerase chain reacti on (PCR) and DNA sequencing, taking advantage of all known kinases con taining a conserved catalytic domain. Our data demonstrated that the e xpression patterns of kinases in various cultured neurons are not only different from those of non-neural tissues, but also distinct among n eurons derived from discrete origins. For example, FGF receptor 1 is p redominantly expressed in hippocampal neurons. As this approach may be biased during PCR and cloning steps, an RNase protection assay was em ployed to verify the expression levels of six kinases in cultured neur ons. Results from the RNase protection assay did generally confirm tho se obtained by the PCR-based method. However, quantitative nature of t he latter was dependent on numbers of clones analyzed, and discrepancy of expression levels of kinases detected by the two methods was somet imes observed.