Class III β-Tubulin Is a Component of the Mitotic Spindle in Multiple Cell Types

Abstract

S U M M A R Y The findings of this study show that Class III b-tubulin is a component of the mitotic spindle in multiple cell types. Class III b-tubulin has been widely used as a neuronspecific marker, but it has been detected also in association with breast and pancreatic cancers. In this study, we describe a novel finding of Class III b-tubulin in a subpopulation of cells in malignant peripheral nerve sheath tumor. The findings of this study also show that Class III b-tubulin is expressed by normal mesenchymal and epithelial cells (fibroblasts and keratinocytes), two transitional cell carcinoma cell lines, and neurofibroma Schwann cells, as shown by immunolabeling and Western transfer analysis using two different Tuj-1 antibodies that are specific for Class III b-tubulin. The corresponding mRNA was detected using RT-PCR and whole human genome microarrays. Both antibodies localized Class III b-tubulin to the mitotic spindle and showed a colocalization with a-tubulin. The immunoreaction became visible in early prophase, and the most intense immunoreaction was detected during metaphase and anaphase when microtubules were connected to the kinetochores on chromosomes. Class III b-tubulin-specific immunoreaction lasted to the point when the midbody of cytokinesis became detectable.

Transcriptional and post-transcriptional regulation of βIII-tubulin protein expression in relation with cell cycle-dependent regulation of tumor cells

“…Furthermore, TUBB3 expression has been demonstrated by immunohistochemistry in the large intestine, fibroblasts and keratinocytes under physiological conditions (9,10). These lines of evidence support our finding that TUBB3 is an important component in mitosis.…”

“…The protein of TUBB3 is often used as a specific differentiation marker for neurons, being immunostained by the antibody Tuj-1 (8). However, it appears that TUBB3 protein expression is not absolutely neuron-specific, there is evidence that TUBB3 is expressed at a low level in normal large intestine, fibroblasts and keratinocytes (9,10). Therefore, it is uncertain whether the afore-mentioned abnormal ectopic expression of TUBB3 protein in certain non-neuronal tumors is dependent on chromatin remodeling or transcriptional de-repression and/ or activation.…”

Human mesenchymal stem cells express neuronal markers after osteogenic and adipogenic differentiation

“…Our hypothesis is supported by literature data reporting that neuronal, glial and progenitor markers can be expressed in cells that are other than neural ones. The early neuronal marker III-tubulin, abundantly expressed in the central and peripheral nervous system [16], is also present in non-neural tissues, both in embryonic and adult stages [16,42], in tumor cells [43,44] and as a component of the mitotic spindles of many cell types [45]. Nestin, considered a major neural progenitor marker [46], has also been found in extra-neural tissues [47] and various types of human solid tumors [48], and has been considered a predictor of poor prognosis in patients with malignant melanoma [49].…”

The Development of Cutaneous Neurofibromas

“…The cells in these sheets were characterized by using indirect immunolabeling and Western blot analysis for different stem cell markers, as described previously. 20 For the NF1 mutation analysis and further differentiation of the cells, single floating cells (or cell spheres) were captured with a micropipette under inverted light microscope and seeded onto 10-cm 2 culture plates containing previously defined stem cell growth medium.…”

“…20 The cells were photographed with Leica DMRB fluorescence microscope (Leica, Wetzlar, Germany). Confocal laser scanning microscopy was carried out using Zeiss LSM 510 META confocal microscope (Zeiss, Jena, Germany) and LSM 3.0 software (Zeiss).…”