Enhancement of mouse egg activation by the kinase inhibitor, 6-dimethylaminopurine (6-DMAP).

Metaphase arrest in vertebrate eggs is maintained by the action of cytostatic factor (CSF) on maturation promoting factor (MPF). In amphibian eggs, the kinase inhibitor, 6-dimethylaminopurine (6-DMAP) inactivates both CSF and MPF, resulting in the release from metaphase and entry into interphase. In the mouse, 6-DMAP induces nuclear formation in maturing oocytes, but not in eggs at metaphase II. We found that 6-DMAP accelerated the transition to interphase in mouse eggs treated with the parthenogenetic agents A23187, cycloheximide, or phorbol 12-myristate 13-acetate (PMA). Newly ovulated eggs, refractory to full activation by A23187, entered interphase when treated with A23187 and 6-DMAP in combination. Occasional batches of eggs formed nuclei in response to 6-DMAP alone. These results are discussed with regard to the possible effects of 6-DMAP on MPF and CSF.