Glioblastomas are the most common and the deadliest types of brain tumours. Due to their highly invasive behaviour, they are incurable by convencial therapeutical strategies. It was shown that some components of microtubules, namely class III β-tubulin, γ-tubulin and microtubule severing protein spastin are overexpressed in glioblastoma cell lines as well as glioblastomas. This diploma thesis is focused on the expression, subcellular distribution and function of katanin, another microtubule-severing enzyme, in gliobastoma cell lines. Katanin is formed by catalytic (p60) and regulatory (p80) subunits. Expression and cellular localization of both katanin subunits was studied in panel of human glioblastoma cell lines isolated form adults (T98G, U87MG, U118MG and U138 MG) and child (KNS42). Data presented in this thesis demonstrated that katanin subunits were overexpresed both on transcript and protein levels in T98G, U87MG and KNS42 cell lines, but not in U138MG and U118MG cell lines when compared to normal non- transformed human astrocytes. Immunofluorescence microscopy revealed that both katanin subunits were diffusively distributed in cytoplasm and concentrated on spindle poles of mitotic cells and on leading edges of migrating cells. Examination of cell motility revealed that velocities in...

Microtubules (MT) are regulated by multiple categories of proteins, including proteins responsible for severing MTs that are therefore called MT-severing proteins. Studies of katanin, spastin, and fidgetin in animal systems have clarified that these proteins are MT-severing. However, studies in plants have been limited to katanin p60, and little is known about spastin or fidgetin and their function in plants. I looked at plant genomes to identify MT-severing protein homologues to clarify which severing proteins exist in plants. I obtained data from a variety of eukaryotic species to look for MT-severing proteins using homology to human proteins and analyzed these protein sequences to obtain information on the evolution of MT-severing proteins in different species. I focused this analysis on MT-severing proteins in the maize and Arabidopsis thaliana genomes. I created evolutionary phylogenetic trees for katanin-p60, katanin-p80, spastin, and fidgetin using sequences from animal, plant, and fungal genomes. I focused on Arabidopsis spastin and worked to understand its functionality by identifying protein interaction partners. The yeast two-hybrid technique was used to screen an Arabidopsis cDNA library to identify putative spastin interactors. I sought to confirm the putative protein interactions by using molecular tools for protein localization such as the YFP system. Finally, a Biomolecular Fluorescence Complementation (BiFC) assay was initiated as a proof of concept for confirmation of in vivo protein-protein interaction.