Morphological and quantitative analysis on α-tubulin modifications in glioblastoma cells

Glioblastoma is one of the primary tumors of the brain with high invasiveness and lethality. In the study of its pathophysiology in recent years much attention has been paid to the microtubular network, but exclusively to β- III tubulin, whose presence in glioblastoma cells is associated with the degree of malignancy and diffusion. As is well known, the microtubular network performs its many functions thanks to various post-translational modifications, most of which affect the α-tubulin subunit. These modifications, able to coexist in the same microtubule, bind certain driving and cargo proteins, deeply influencing cellular functions. Since there are no data in the literature about the diverse post-translational modifications of tubulin in glioblastoma cells, this work aims to fill this gap. In the present work, through immunofluorescence, morphological analysis and Western blot, we studied the pattern of tyrosinated, detyrosinated, delta 2 (Δ2), acetylated and polyglutamylated tubulin. We detected good immunopositivity in fluorescence for almost all the modifications examined. Only Δ2 showed a very low signal. Western blot displayed that the most abundant tubulin modifications in glioblastoma cells were tyrosinated, acetylated and polyglutamylated. Morphological evaluation revealed that these modifications were more present along the cytoplasmic extensions, less evident around the cell body and always strongly evident in the mitotic spindles of the dividing cells. For the first time, the most abundant post-translational modifications and their cellular compartmentalization in glioblastoma cells have been highlighted, suggesting a novel approach in the study of their microtubular network and in the search of new experimental therapeutic strategies.