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.