Class III β-Tubulin and γ-Tubulin are Co-expressed and Form Complexes in Human Glioblastoma Cells

We have previously shown that the neuronal-associated class III β-tubulin isotype and the centrosome-associated γ-tubulin are aberrantly expressed in astrocytic gliomas (Cell Motil Cytoskeleton 2003, 55:77-96; J Neuropathol Exp Neurol 2006, 65:455–467). Here we determined the expression, distribution and interaction of βIII-tubulin and γ-tubulin in diffuse-type astrocytic gliomas (grades II-IV) ( n = 17) and the human glioblastoma cell line T98G. By immunohistochemistry and immunofluorescence microscopy, βIII-tubulin and γ-tubulin were co-distributed in anaplastic astrocytomas and glioblastomas and to a lesser extent, in low-grade diffuse astrocytomas ( P < 0.05). In T98G glioblastoma cells βIII-tubulin was associated with microtubules whereas γ-tubulin exhibited striking diffuse cytoplasmic staining in addition to its expectant centrosome-associated pericentriolar distribution. Treatment with different anti-microtubule drugs revealed that βIII-tubulin was not associated with insoluble γ-tubulin aggregates. On the other hand, immunoprecipitation experiments unveiled that both tubulins formed complexes in soluble cytoplasmic pools, where substantial amounts of these proteins were located. We suggest that aberrant expression and interactions of βIII-tubulin and γ-tubulin may be linked to malignant changes in glial cells.