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Dev Biol. 1991 May;145(1):119-27.

Stimulatory effect of okadaic acid, an inhibitor of protein phosphatases, on nuclear envelope breakdown and protein phosphorylation in mouse oocytes and one-cell embryos.

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Department of Biology, University of Pennsylvania, Philadelphia 19104-6018.


Treatment of one-cell mouse embryos with okadaic acid (OA), which is an inhibitor of protein phosphatases 1 and 2A, induces a concentration-dependent precocious nuclear envelope breakdown (NEBD) of the pronuclei; at 10 microM okadaic acid, NEBD starts to occur after 1 hr and the embryos become committed to NEBD after about 45 min. Correlated with NEBD is the conversion of a protein of Mr 32,000 (p32) to more highly phosphorylated forms. One-cell embryos cultured continuously in OA-containing medium do not cleave, whereas one-cell embryos incubated for 15-60 min prior to transfer to OA-free medium reveal a time-dependent inhibition in their ability to cleave. OA treatment of oocytes that are arrested from resuming spontaneous maturation by either a phosphodiesterase inhibitor or biologically active phorbol diester results in germinal vesicle breakdown and the maturation-associated changes in the pattern of protein phosphorylation, which include the apparent phosphorylation of p32. Results of these experiments implicate protein phosphatases in the G2 to M transition of the cell cycle in both meiotic and mitotic cells.

[Indexed for MEDLINE]

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