Cytoplasmic anchoring of cAMP-dependent protein kinase (PKA) by A-kinase anchor proteins (AKAPs) is required for meiotic arrest of porcine full-grown and growing oocytes.

Mammalian growing oocytes (GOs) lack the ability to resume meiosis, although the molecular mechanism of this limitation is not fully understood. We previously hypothesized that the meiotic incompetence of porcine GOs was attributed to complex spatial-temporal regulation of cAMP-dependent protein kinase by A-kinase anchor proteins (AKAPs), but found that AKAP1 is not involved in the meiotic incompetence of porcine GOs. In the present study, we cloned porcine cDNAs of AKAP5 and AKAP7alpha, and found that inhibiting the expression of these AKAPs induced translocation into the nucleus and promoted meiotic resumption of porcine GOs without affecting the total duanyu1529 activity of GOs, whereas overexpressing these AKAPs had no effect. Because AKAPs regulate duanyu1529 localization through binding with regulatory subunits of duanyu1529 binding with AKAPs was inhibited by AKAP-binding inhibition peptides or duanyu1529-R expression inhibition by antisense RNAs. We found that the expression inhibition and binding inhibition of PRKAR1A, an isoform of mammalian promoted meiotic resumption of porcine GOs, whereas these inhibitions of PRKAR2A, another duanyu1529-R isoform, had no effect. In contrast, the expression inhibition and binding inhibition of PRKAR2A had higher effects than those of PRKAR1A on meiotic resumption of porcine full-grown oocytes. These results suggest that cytoplasmic anchoring of duanyu1529 by AKAPs is required for meiotic arrest of oocytes and that the duanyu1529-R isoform working for the maintenance of meiotic arrest changed from PRKAR1A to PRKAR2A during the acquisition of meiotic competence.

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