Document Detail

Inhibition of mouse egg chromosome decondensation due to meiotic apparatus derangement induced by the protein phosphatase inhibitor, okadaic acid.
MedLine Citation:
PMID:  8972585     Owner:  NLM     Status:  MEDLINE    
The transition from metaphase to interphase involves protein dephosphorylation. Genetic and immunologic evidence suggest that protein phosphatase (PP) 1 and PP 2A may be required for this transition. Okadaic acid, a specific inhibitor of PP 1 and 2A, prevents the exit from metaphase in mammalian cells, but also disrupts the mitotic apparatus. Since disruption of the spindle itself causes cell cycle arrest, the present study was carried out to determine whether okadaic acid-treated cells fail to exit from metaphase because PP 1 and/or 2A activity is required, or because of spindle disruption. It was possible to distinguish between these two alternatives by including the protein kinase inhibitor, 6-dimethylaminopurine (6-DMAP), in the culture medium, since cells treated with 6-DMAP exit from metaphase despite disruption of the spindle. Mouse eggs, physiologically arrested at metaphase of the second meiotic division, complete meiosis and enter interphase when exposed to the calcium ionophore A23187. When eggs were exposed to 80 or 100 nM okadaic acid for 8 h, the meiotic spindle disappeared and the chromosomes disjoined. Nuclei did not form in eggs treated with okadaic acid and A23187, but did form in eggs treated with okadaic acid, A23187, and 6-DMAP. Therefore, eggs treated with okadaic acid have the capacity to exit from metaphase and enter interphase.
R M Moses
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of experimental zoology     Volume:  276     ISSN:  0022-104X     ISO Abbreviation:  J. Exp. Zool.     Publication Date:  1996 Dec 
Date Detail:
Created Date:  1997-01-22     Completed Date:  1997-01-22     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0375365     Medline TA:  J Exp Zool     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  369-74     Citation Subset:  IM    
Department of Zoology, University of Toronto, Ont., Canada.
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MeSH Terms
Okadaic Acid / pharmacology*
Ovum / drug effects*,  ultrastructure
Phosphoprotein Phosphatases / antagonists & inhibitors*
Reg. No./Substance:
78111-17-8/Okadaic Acid; EC Phosphatases

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