PKC는 그들의 cofactor-requirments에 따라 cPKC, nPKC 그리고 aPKC, 3그룹으로 나어진다. 마우스 난 성숙과정에 있어서 cPKC 및 nPKC의 activators인 PMA의 영향에 대한 많은 결과가 보고되었다. 그러나 각각의 그룹에 대한 차별화된 영향에 대하여는 밝혀져 있지 않다. Mezerein의 analog인 thymeleatoxin은 cPKC의 특이적인 activator로 보고되어져 있다. 본 연구에서는 specific cPKC activator인 thymeleatoxin의 마우스 난 성숙과정에의 영향을 제1감수분열 재개 능(germinal vesicle break down, GVBD)과 제1 극체 형성 능(1st polar body extrusion)을 조사하여 cPKC및 nPKC activator인 PMA와 비교 검토하였다. 그 결과 GVBD IC50는 thymeleatoxin에서 ～400nM, PMA에서는 ～50nM이었으며, 제1극체 방출의 IC50는 thymeleatoxin에서 ～200nM, PMA에서는 ～20nM이었다. 이들 결과는 Thymeleatoxin의 GVBD나 1st polar body extrusion 저해효과가 PMA에 비하여 1/8～1/10인 것으로 나타났다. 이들 결과는 GVBD나 제1극체 형성을 포함하는 난 성숙과정에서 cPKC보다 상대적으로 nPKC의 관여가 깊음을 보여 준다.
Protein kinase C exists as a family of serine/threonine kinases which are broadly classified into three groups as cPKC nPKC and aPKC depending on their cofactor requirements. Previous studies have shown that the role of PKC in the process of mouse oocyte maturation. For example, phorbol 12-myristate 13-acetate which is known as an activator of cPKC and nPKC inhibits germinal vesicle break down and 1st polar body extrusion in maturing oocytes. In this study, the effect of thymeleatoxin, a specific activator of cPKC not nPKC, was tested comparing with PMA to address the roles of cPKC and nPKC during mouse oocyte maturation. Cumulus-oocyte complex were cultured in M16 medium for 6 or 12 hr with each of these PKC activators to investigate the effect of germinal vesicle breakdown (GVBD) or the extrusion of 1st polar body. IC50 of GVBD were at concentrations of 50nM in PMA and 400nM in thymeleatoxin and of 1st polar body extrusion were 20nM in PMA and 200nM in thy- meleatoxin. The results suggest that activation of nPKC is more closely related to the inhibition of GVBD and 1st polar body extrusion than activation of cPKC. Additionally, we found that the oocytes inhibited 1st polar body extrusion with PMA or thymeleatoxin were arrested in metaphase I of first meiosis.
