The role of microtubules splitting proteins in regulation of cytoskeleton.

Microtubules are highly dynamic cytoskeletal structures, which secure cell shape, intracellular transport and organization of cellular organelles. They also participate in cell migration and in formation of mitotic spindle. Microtubules create a highly organized network which changes its organisation in response to the immediate need of the cell. They are formed of αβ-tubulin dimers and a large number of associated proteins. Microtubules are a polar structures with (+) and (-) ends, that differ in the rate of assembly. For fast regulation of microtubule structure are important microtubule-severing proteins (spastin, katanin and fidgetin), that belong to the AAA ATPases. These proteins associate with microtubules and consequently sever microtubules into two parts creating new (+) and (-) ends. In this way, they regulate many cellular processes, such as maintaining of cell shape, cell motility, proliferation and differentiation. Beside microtubule-severing activity, spastin and fidgetin are involved in processes in cell nucleus. Spastin is also associated with membranes and participates in modulation of endoplasmic reticulum and generation of endosomal vesicles. Mutations of microtubule-severing proteins cause embryonal development disorders, nervous system defects or infertility. The latest research..