蛋白激酶C对精子活力和顶体反应的影响

Influence of Protein Kinase C on Motility and Acrosome Reaction of Sperm

蛋白激酶C(PKC)位于精子头部赤道段和尾部主段。外源性PKC激动剂可增强精子鞭毛的活力 ,而PKC抑制剂如癌基因抑活药 (staurosporine)则能抑制这种作用。精子中PKC的含量与精子活力呈显著正相关 (r =0 .9,P <0 .0 0 1)。精子与透明带 (ZP)结合刺激顶体反应的发生 ,导致顶体释放多种水解酶以及精子暴露出新的膜区域。ZP与精子质膜上的受体结合后 ,可以调节腺苷酸环化酶 (AC)的活性 ,使cAMP浓度升高并激活蛋白激酶A(PKA)。PKA能激活位于顶体外膜的电压依赖性钙通道 ,后者使顶体内部的Ca2 + 释放至胞质中 ,磷脂酶C(PLC)因Ca2 + 浓度升高而激活并水解磷脂酰肌醇二磷酸 ,其水解产物激活PKC ,后者使精子质膜上电压依赖性钙通道 (L型 )开放 ,胞质中第二次较大幅度Ca2 + 浓度的上升导致质膜溶解及顶体反应发生。

Protein kinase C (PKC) is localized in the equatorial segment and the principal piece of the tail of spermtozoa. Activator of PKC results in increasing flagellar motility of sperm that is blocked by PKC inhibitors such as staurosporine. A good correlation ( r =0.9, P <0.001) is found between the content of PKC in sperm and sperm motility. Zona pellucida (ZP) stimulates the spermatozoa binding the acrosome reaction resulting in the release of hydrolytic enzymes and in the exposure of new membrane domains. ZP binding to receptors in the plasma membrane can regulate adenyl cyclase (AC) leading to elevation of cAMP and protein kinase A (PKA) activation. The PKA activates a voltage dependent Ca 2+ channel in the outer acrosomal membrane which releases Ca 2+ from the interior of the acrosome to the cytosol. Activation of the PLC resulted from the rise in Ca 2+ hydrolyze phosphatidyl inositol bisphosphate. The product activate PCK to open a voltage dependent Ca 2+ channel (L) in the plasma membrane, leading to the second (Ⅱ) Ca 2+ higher increase which result in membrane fusion and acrosome reaction. It is proposed that PKC would be involved in the regulation of motility and acrosome reaction of sperm.