Liu Y, Qu F, Cao X, Chen G, Guo Q, Ying X, Guo W, Lu L, Ding Z
Key Laboratory for Reproductive Medicine, Department of Histology and Embryology, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
Int J Androl. 2012 Apr;35(2):145-57. doi: 10.1111/j.1365-2605.2011.01195.x. Epub 2011 Jul 26.
Fertilization, the recognition and fusion between spermatozoa and oocyte, involves various molecules on the spermatozoa and oocyte membranes. Concanavalin A (ConA)-binding proteins may be one of the molecules involved in mammal spermatozoa fertilization; however, their structure and function remain largely unknown. Here, we initially identified a ConA-binding protein, Zn-α2-glycoprotein (ZAG), involved in regulating the acrosome reaction (AR) of human spermatozoa. ZAG is localized on the pre-equatorial region covering the acrosome, neck and tail (some parts of middle piece and principal piece respectively) regions of the acrosome intact human spermatozoa, and disappears in the acrosomal region of the acrosome-reacted spermatozoa. Polyclonal antibodies against human recombinant ZAG significantly reduced the AR and sperm capability binding to human zona pellucida or penetration into zona-free hamster oocytes. Furthermore, assessment of the signaling pathways regulated by ZAG revealed that ZAG affects sperm AR through both the cAMP/PKA and PKC pathways. These results indicate that ZAG, which is present on the human sperm membrane, plays a critical role in the AR and subsequently, may be involved in sperm fertility.
受精是精子与卵母细胞之间的识别与融合过程，涉及精子和卵母细胞膜上的多种分子。伴刀豆球蛋白A（ConA）结合蛋白可能是参与哺乳动物精子受精的分子之一；然而，它们的结构和功能在很大程度上仍不清楚。在此，我们最初鉴定出一种参与调节人类精子顶体反应（AR）的ConA结合蛋白，即锌-α2-糖蛋白（ZAG）。ZAG定位于覆盖完整顶体的赤道前区域、顶体完整人类精子的颈部和尾部（分别为中段和主段的某些部分）区域，并在发生顶体反应的精子的顶体区域消失。针对人重组ZAG的多克隆抗体显著降低了AR以及精子与人透明带结合或穿透无透明带仓鼠卵母细胞的能力。此外，对ZAG调节的信号通路的评估表明，ZAG通过cAMP/PKA和PKC通路影响精子AR。这些结果表明，存在于人类精子膜上的ZAG在AR中起关键作用，随后可能参与精子的生育能力。
