Mitotic chromatin regulates phosphorylation of Stathmin/Op18

• Published in: Nature (London) Vol. 389; no. 6651; pp. 640 - 643
• Main Authors: Andersen, Søren S. L, Ashford, Anthony J, Tournebize, Rgis, Gavet, Olivier, Sobel, Andr, Hyman, Anthony A, Karsenti, Eric
• Format: Journal Article
• Language: English
• Published: London Nature Publishing 09-10-1997; Nature Publishing Group
• Subjects: Animals; Binding Sites; Biological and medical sciences; CDC2 Protein Kinase - metabolism; Cell cycle, cell proliferation; Cell physiology; Chromatin - physiology; Cloning, Molecular; Fundamental and applied biological sciences. Psychology; Life Sciences; Microtubule Proteins; Mitosis; Molecular and cellular biology; Mutagenesis, Site-Directed; Phosphoprotein Phosphatases - metabolism; Phosphoproteins - genetics; Phosphoproteins - metabolism; Phosphorylation; Spindle Apparatus - metabolism; Stathmin; Xenopus; Xenopus Proteins; Chromatin; Phosphorylation; Xenopus laevis; Amphibia; Polymerization; Salientia; Mitotic spindle; In vitro; Stathmin; Vertebrata; Phosphoproteins; Cell cycle; Microtubule; Oocyte
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/39382

Meiotic and mitotic spindles are required for the even segregation of duplicated
chromosomes to the two daughter cells. The mechanism of spindle assembly is
not fully understood, but two have been proposed that are not mutually exclusive. The 'search and capture' model suggests that
dynamic microtubules become progressively captured and stabilized by the kinetochores
on chromosomes, leading to spindle assembly,.
The 'local stabilization' model proposes that chromosomes change
the state of the cytoplasm around them, making it more favourable to microtubule
polymerization,. It has been shown, that Stathmin/Op18 inhibits microtubule polymerization
in vitro by interaction with tubulin, and that overexpression
in tissue culture cells of non-phosphorylatable mutants of Stathmin/Op18 prevents
the assembly of mitotic spindles. We have used Xenopus
egg extracts and magnetic chromatin beads to show that
mitotic chromatin induces phosphorylation of Stathmin/Op18. We have also shown
that Stathmin/Op18 is one of the factors regulated by mitotic chromatin that
governs preferential microtubule growth around chromosomes during spindle
assembly.