Microtubule cycle, regulation

Finally, 80 proteins localized to an abnormal intranuclear microtubule structure upon LMB treatment, while others simply occupied nucleus or nucleolus. Crml-dependent dynamic interchange of proteins between the nucleus and the microtubules may regulate microtubule organization during the cell cycle in fission yeast. Further analysis of individual proteins will reveal the involvement of Crml in the process for microtubule assembly and disassembly. 

Cyclic uptake and release of Ca2+ from the extracellular medium occur during mitosis in Physarum pofycephalum, and correlate with specific structural and kinetic events in the mitotic nuclei.442 The membrane system in the mitotic apparatus in Haemantkus endosperm cells functions in the localized release of Ca2+, so regulating the events of mitosis.443 It is known that calcium exerts effects on the stability of spindle microtubules. An alternative view is that free magnesium concentration acts as the fundamental regulator of the cell cycle.444 Tubulin polymerization depends on the presence of magnesium and the absence of calcium, and control of the Ca2+/Mg2+ ratio is relevant to spindle assembly. 

Cassimeris, L. (1999). Accessory protein regulation of microtubule dynamics throughout the cell cycle. Curr. Opin. CellBiol. 11, 134—141. 

Sontag E, Nunbhakdi-Craig V, Bloom GS et al (1995) A novel pool of protein phosphatase 2A is associated with microtubules and is regulated during the cell cycle. J Cell Biol 128 1131-1144... 

The microtubule cytoskeleton plays an important role in maintaining and regulating cell division. Microtubules are polymers that consist of a- and (3-tubulin heterodimers. In the process of mitosis, microtubules undergo dynamic cycles of lengthening (polymerizatiOTi) and shortening (depolymerization), and these cycles are critical for chromosome attachment to the mitotic spindle and for appropriate chromosome segregation. Thus, perturbation of microtubule dynanucs by either mechanism provides effective anticancer approaches. 

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