Translocation of classical PKC and cortical granule exocytosis of human oocyte in germinal vesicle and metaphase II stage

Abstract

Protein kinase C (PKC) is as a family of serine/threonine kinases that can be activated by Ca2+, phospholipid and diacylglycerol. PKC plays an important role in oocyte maturation and activation. This study was undertaken to investigate classical PKC (cPKC) in human oocyte maturation and activation. Germinal vesicle (GV) and metaphase II (MII) stage oocytes were collected from healthy women. The expression and distribution of cPKC were investigated by immunoflourescence. MII oocytes were treated with PKC activator or inhibitor and imaged using a laser confocal scanning microscope (LCSM). In GV oocytes, PKCalpha, beta1 and gamma were localized to the germinal vesicles, with a weak expression in ooplasm. In MII oocytes, PKCalpha, beta1 and gamma were distributed evenly in ooplasm. After treatment with PKC activator, phorbol 12-myristate 13-acetate (PMA), cPKC translocated to the periphery of oocyte, and cortical granules (CG) exocytosis was found. When the oocytes were treated with PKC inhibitor, staurosporine, no translocation of cPKC and CG exocytosis were found. PKCalpha, beta1 and gamma exist in human oocytes and activation of these subunits could induce CG exocytosis in MII stage.