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Published July 1993 | public
Journal Article

Okadaic Acid Affects Spindle Organization in Metaphase II-Arrested Rat Oocytes

Abstract

We used okadaic acid (OA), a potent phosphatase inhibitor, to study the role of phosphatases in the organization of the spindle microtubules in metaphase II-arrested rat oocytes. OA induced a dramatic elongation of the spindle and disorganization of the metaphase plate. Biochemical analysis revealed some dramatic changes after OA treatment: increased histone H1 kinase activity, a burst of protein phosphorylation, and inhibition of protein synthesis. The latter effect alone cannot be responsible for the changes in the spindle structure since inhibition of protein synthesis with puromycin had no such effect. To identify the targets of OA among the proteins associated with the spindle, meiotic spindles of OA-treated and control oocytes were purified. After OA treatment some proteins gained and others lost their association with the spindle, A few proteins that lost their affinity for the spindle also underwent hyperphosphorylation after OA treatment. These results suggest that hyperphosphorylation of some proteins associated with the spindle alters their affinity to microtubules and thus stabilizes them.

Additional Information

© 1993 Academic Press. Received December 10, 1992. Revised version received February 16, 1993. We thank Professor A. K. Tarkowski , Dr. J. Kubiak, and N. Winston for critical reading of the manuscript and R. Schwartzmann and G. Géraud for their expert photographic work. We are grateful to Dr. J. Kilmartin for the gift of the YL 1/2 antibody. This work was supported by grants from INSERM, La Ligue, ARC, and FRM. M.Z.G. was the recipient of a CNRS fellowship.

Additional details

Created:
August 20, 2023
Modified:
October 20, 2023