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Comment |
Fan HY, et al 2002 reported the translocation of the classic protein kinase C Isoforms in
porcine oocytes: Implications of protein kinase C involvement
in the regulation of nuclear activity and cortical granule
exocytosis
Protein kinase C (PKC) is a family of Ser/Thr protein kinases categorized into
three subfamilies: classical, novel, and atypical. The subcellular
localization of classical PKCalpha, -betaI, and -gamma in the process of
porcine oocyte maturation, fertilization, and parthenogenetic activation and
their involvement in cortical granule (CG) exocytosis were investigated. The
results of Western blot showed that PKCalpha, -beta I, and -gamma were
expressed in the oocytes at the germinal vesicle (GV) and metaphase II (MII)
Stages. Confocal microscopy revealed that the three PKC isoforms were
concentrated in the GV but evenly distributed in the cytoplasm of AIII eggs.
PKCalpha and -gamma were translocated to the plasma membrane soon after sperm
penetration. cPKCs migrated into the pronucleus in fertilized eggs. Following
treatment with a PKC activator, phorbol 12-myristate 13-acetate (PMA), CGs
were released and PKCalpha and -gamma were translocated to the membrane. The
CG exocytosis and PKC redistribution induced by PMA could be blocked by the
PKC inhibitor staurosporine. Parthenogenetic stimulation with ionophore A23187
or electrical pulse also induced cPKC translocation and CG exocytosis. Eggs
injected with PKCalpha isoform-specific antibody failed to undergo CG
exocytosis after PMA treatment or fertilization. The results suggest that
cPKCs, especially the alpha-isotype, regulate nuclear function and CG
exocytosis in porcine eggs.
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