TrkAIII promotes microtubule nucleation and assembly at the centrosome in SH-SY5Y neuroblastoma cells, contributing to an undifferentiated anaplastic phenotype.

The alternative TrkAIII splice variant is expressed by advanced stage human neuroblastomas (NBs) and exhibits oncogenic activity in NB models. In the present study, employing stable transfected cell lines and assays of indirect immunofluorescence, immunoprecipitation,Western blotting, microtubule regrowth, tubulin kinase, and tubulin polymerisation, we report that TrkAIII binds -tubulin and promotes MT nucleation and assembly at the centrosome. This effect depends upon spontaneous TrkAIII activity, TrkAIII localisation to the centrosome and pericentrosomal area, and the capacity of TrkAIII to bind, phosphorylate, and polymerise tubulin.We propose that this novel role for TrkAIII contributes toMT involvement in the promotion and maintenance of an undifferentiated anaplastic NB cell morphology by restricting and augmentingMT nucleation and assembly at the centrosomal MTOC.