TrkAIII promotion of MT nucleation and assembly at the centrosome bears close similarity to the influence of c-Src upon MT nucleation and assembly, which has been reported to depend upon the recruitment of γ-tubulin ring structures to the centrosome [ 23, 24].
We propose that this novel role for TrkAIII contributes to MT involvement in the promotion and maintenance of an undifferentiated anaplastic NB cell morphology by restricting and augmenting MT nucleation and assembly at the centrosomal MTOC.
In conclusion, we propose that spontaneous intracellular pericentrosomal TrkAIII activation contributes to MT involvement in the promotion and maintenance of a proliferating, undifferentiated, and anaplastic NB cell phenotype by restricting and augmenting MT nucleation and assembly to the centrosomal MTOC.
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 α -tubulin and promotes MT nucleation and assembly at the centrosome.
However, the fact that TrkAIII contemporarily binds α and γ-tubulin (this study and [ 4]) suggests that TrkAIII may independently recruit α and γ-tubulin to the centrosome for MT nucleation and assembly.
Here, we report that TrkAIII interacts with α-tubulin and promotes tubulin polymerisation, contributing to MT involvement in promoting and maintaining a proliferating, undifferentiated, and anaplastic NB cell phenotype by restricting and augmenting MT nucleation and assembly at the interphase centrosome.
It has been recently shown that the Nup 107 160 complex recruits γ-TuRC at the level of kinetochores promoting MT nucleation and K-fiber assembly; however, this mechanism would produce MTs of opposite polarity (Mishra et al., 2010).
In summary, these data support the model that Cdk1 and Mps1 phosphorylations of Spc110 regulate γ-TuSC-mediated MT nucleation by controlling template assembly.
The central finding of our work is that gradients of cortical MT nucleation are sufficient for the assembly of a functional compartmentalised MT cytoskeleton in wild-type oocytes.
Co-overexpression of SPC97, SPC98, and TUB4 does not induce MT nucleation despite of γ-TuSC assembly (Pereira et al., 1998).
