The biological and functional significance of the sperm acrosome and acrosomal enzymes in mammalian fertilization.
The biological and functional significance of the sperm acrosome and acrosomal enzymes in mammalian fertilization.
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DOI：
10.1006/excr.1998.3943
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发表时间：
1998-05
影响因子：
3.7
通讯作者：
D. Tulsiani;A. Abou-haila;C. Loeser;Ben M.J. Pereira
中科院分区：
文献类型：
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作者：
D. Tulsiani;A. Abou-haila;C. Loeser;Ben M.J. Pereira
哺乳动物精子在精子发生、附睾成熟和雌性生殖道获能过程中经历了不断的修饰。只有有能力的精子才能与带完整的卵子结合并进行顶体反应。受精过程是多种分子事件的最终结果，这些事件使射精精子能够识别并结合到卵子的细胞外外壳，即透明带（ZP）。精子-卵子相互作用是一种物种特异性的事件，它是由存在于精子质膜（受体）和ZP（配体）表面的互补分子的识别和结合引起的。这是一个碳水化合物介导的事件，它启动了一个信号转导级联，导致顶体内容物的胞吐。这一步骤被认为是使顶体反应的精子能够穿透ZP并使卵子受精的先决条件。本文就精子顶体的形成、内容以及顶体反应的诱导机制作一综述。特别强调了顶体内酸性糖水解酶的合成、加工、底物特异性和作用机制。在精子带结合部位释放的糖水解酶和蛋白酶的水解作用，以及结合精子的高激活模式所产生的增强推力，是调节ZP渗透的重要因素。我们讨论了最近的研究，这些研究试图解释导致顶体胞吐的信号转导途径。
The mammalian spermatozoon undergoes continuous modifications during spermatogenesis, maturation in the epididymis, and capacitation in the female reproductive tract. Only the capacitated spermatozoa are capable of binding the zona-intact egg and undergoing the acrosome reaction. The fertilization process is a net result of multiple molecular events which enable ejaculated spermatozoa to recognize and bind to the egg's extracellular coat, the zona pellucida (ZP). Sperm-egg interaction is a species-specific event which is initiated by the recognition and binding of complementary molecule(s) present on sperm plasma membrane (receptor) and the surface of the ZP (ligand). This is a carbohydrate-mediated event which initiates a signal transduction cascade resulting in the exocytosis of acrosomal contents. This step is believed to be a prerequisite which enables the acrosome reacted spermatozoa to penetrate the ZP and fertilize the egg. This review focuses on the formation and contents of the sperm acrosome as well as the mechanisms underlying the induction of the acrosome reaction. Special emphasis has been laid on the synthesis, processing, substrate specificity, and mechanism of action of the acid glycohydrolases present within the acrosome. The hydrolytic action of glycohydrolases and proteases released at the site of sperm-zona binding, along with the enhanced thrust generated by the hyperactivated beat pattern of the bound spermatozoon, are important factors regulating the penetration of ZP. We have discussed the most recent studies which have attempted to explain signal transduction pathways leading to the acrosomal exocytosis.