RESUMO
During development, the regulation of expression of the Trk family of tyrosine kinase receptors plays an important role in defining the cellular responses to neurotrophin action. We report here that neurotrophin receptors are differentially expressed in distinct populations of retinoic acid-differentiated P19 cells. TrkB, the tyrosine kinase receptor for brain-derived neurotrophic factor, and LNGFR, the low-affinity receptor for all neutrophins, are preferentially expressed in P19-derived neurones. In contrast, retinoic acid induces the expression of TrkA, the high-affinity receptor for nerve growth factor, and of a non-catalytic form of TrkB, in non-neural subsets of differentiated cells. We propose P19 cells as a model system to study the mechanisms controlling the expression of neurotrophin receptors and the responsiveness of developing neurones to a specific neurotrophin.
