| Summary: | Microtubules (MTs) play crucial roles in intracellular organization and transport, cell polarity, motility, signalling, division and differentiation. MTs form complex arrays, which are, due to their highly dynamic nature, capable of rapid reorganization in response to cellular requirements. Dynamics, stability and spatial organization of MTs are regulated by many factors including MT regulatory proteins. In the presented study we functionally characterized three selected MT regulatory proteins: Ca2+ -sensor STIM1, MT severing protein spastin and γ-tubulin that is essential for MT nucleation. We found out that activation of bone marrow mast cells (BMMCs) leads to the formation of plasma membrane protrusions containing MTs. Formation of these MT protrusions is dependent on an influx of extracellular Ca2+ regulated by protein STIM1, located in endoplasmic reticulum. STIM1 associates with MTs and its depletion prevents formation of MT protrusions. This indicates that Ca2+ ions might be involved in MT regulation. Since STIM1 depletion also causes defects in chemotaxis, we propose that MT protrusions might be involved in sensing of external signals recognized by BMMCs. Glioblastoma multiforme is the most common and most aggressive malignant primary brain tumor in humans. We demonstrated that MT severing...
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