Division of Molecular Medicine, Bose Institute, Kolkata, India.
PLoS One. 2012;7(1):e30552. doi: 10.1371/journal.pone.0030552. Epub 2012 Jan 23.
Mammalian sperm capacitation is an essential prerequisite to fertilization. Although progress is being made in understanding the physiology and biochemistry of capacitation, little has been yet explored about the potential role(s) of individual sperm cell protein during this process. Therefore elucidation of the role of different sperm proteins in the process of capacitation might be of great importance to understand the process of fertilization. The present work describes the partial characterization of a 14-kDa protein (p14) detected in goat spermatozoa using an antibody directed against the purified protein. Confocal microscopic analysis reveals that the protein is present in both the intracellular and extracellular regions of the acrosomal and postacrosomal portion of caudal sperm head. Though subcellular localization shows that p14 is mainly cytosolic, however it is also seen to be present in peripheral plasma membrane and soluble part of acrosome. Immuno-localization experiment shows change in the distribution pattern of this protein upon induction of capacitation in sperm cells. Increased immunolabeling in the anterior head region of live spermatozoa is also observed when these cells are incubated under capacitating conditions, whereas most sperm cells challenged with the calcium ionophore A23187 to acrosome react, lose their labeling almost completely. Intracellular distribution of p14 also changes significantly during acrosome reaction. Interestingly, on the other hand the antibody raised against this 14-kDa sperm protein enhances the forward motility of caprine sperm cells. Rose-Bengal staining method shows that this anti-p14 antibody also decreases the number of acrosome reacted cells if incubated with capacitated sperm cells before induction of acrosome reaction. All these results taken together clearly indicate that p14 is intimately involved and plays a critical role in the acrosomal membrane fusion event.
哺乳动物精子获能是受精的必要前提。尽管在理解获能的生理学和生物化学方面取得了进展，但对于在这个过程中单个精子细胞蛋白的潜在作用（s）还知之甚少。因此，阐明不同精子蛋白在获能过程中的作用对于理解受精过程可能非常重要。本工作描述了使用针对纯化蛋白的抗体检测到的山羊精子中 14kDa 蛋白（p14）的部分特征。共聚焦显微镜分析显示，该蛋白存在于顶体和顶体后尾部精子头部的细胞内和细胞外区域。虽然亚细胞定位表明 p14 主要位于细胞质中，但也可以看到它存在于周边质膜和顶体的可溶性部分中。免疫定位实验表明，在诱导精子获能时，该蛋白的分布模式发生变化。当这些细胞在获能条件下孵育时，在活精子的头部前区观察到免疫标记增加，而大多数受到钙离子载体 A23187 挑战以引发顶体反应的精子几乎完全失去其标记。p14 的细胞内分布在顶体反应期间也发生显著变化。有趣的是，另一方面，针对这种 14kDa 精子蛋白的抗体增强了山羊精子的前向运动。玫瑰红孟加拉染色法表明，如果在诱导顶体反应之前与获能精子孵育，这种抗 p14 抗体也会减少顶体反应细胞的数量。所有这些结果都清楚地表明，p14 密切参与并在顶体膜融合事件中发挥关键作用。
