Limited proteolysis by acrosin affects sperm-binding and mechanical resilience of the mouse zona pellucida.
Limited proteolysis by acrosin affects sperm-binding and mechanical resilience of the mouse zona pellucida.
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DOI：
10.1093/molehr/gaab022
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发表时间：
2021-03
影响因子：
4
通讯作者：
Michael Kuske;J. Floehr;I. Yiallouros;Thomas Michna;W. Jahnen-Dechent;S. Tenzer;W. Stöcker;Hagen Körschgen
中科院分区：
文献类型：
--
作者：
Michael Kuske;J. Floehr;I. Yiallouros;Thomas Michna;W. Jahnen-Dechent;S. Tenzer;W. Stöcker;Hagen Körschgen
卵母细胞和精子的相遇是哺乳动物胚胎发育的关键事件。这种存在相互作用的关键功能是由蛋白水解酶决定的，例如精子头顶体中携带的顶体蛋白酶和储存在卵母细胞皮质颗粒中的奥司他辛。受精时释放卵蛋白，切割卵母细胞周围的透明质膜（一种糖蛋白基质）。这种有限的蛋白质水解使卵母细胞的包膜变硬，从而提供了一个针对多精受精的决定性阻断，并保护发育中的胚胎。另一方面，顶体蛋白酶，著名的和最丰富的顶体蛋白酶，已被认为是使精子穿透卵母细胞包膜。根据物种的不同，顶体酶对透明质酸的蛋白水解裂解对于受精是必要的或有益的。然而，这种蛋白水解的特定靶切割位点和由此产生的生理后果仍然不清楚。在这里，我们处理本地小鼠透明带与活性顶体酶，并确定了两个切割位点的透明带蛋白1（ZP 1），五个在ZP 2和一个在ZP 3的质谱。这些位点中有几个在哺乳动物中高度保守。值得注意的是，顶体酶的有限蛋白水解导致透明质酸的重塑而不是降解。因此，顶体酶影响精子结合和机械弹性的透明质酸，分别通过显微镜和纳米压痕测量进行评估。此外，我们确定了潜在的顶体酶的调节作用，通过激活潜在的前ovastacin和失活的胎球蛋白-B，紧密结合的抑制剂ovastacin。这些结果为复杂的蛋白水解网络修饰小鼠卵母细胞的细胞外基质提供了新的见解，这可能也适用于其他物种。
The encounter of oocyte and sperm is the key event initiating embryonic development in mammals. Crucial functions of this existential interaction are determined by proteolytic enzymes, such as acrosin, carried in the sperm head acrosome, and ovastacin, stored in the oocyte cortical granules. Ovastacin is released upon fertilisation to cleave the zona pellucida, a glycoprotein matrix surrounding the oocyte. This limited proteolysis hardens the oocyte envelope, and thereby provides a definitive block against polyspermy and protects the developing embryo. On the other hand, acrosin, the renowned and most abundant acrosomal protease, has been thought to enable sperm to penetrate the oocyte envelope. Depending on the species, proteolytic cleavage of the zona pellucida by acrosin is either essential or conducive for fertilisation. However, the specific target cleavage sites and the resulting physiological consequences of this proteolysis remained obscure. Here, we treated native mouse zonae pellucidae with active acrosin and identified two cleavage sites in zona pellucida protein 1 (ZP1), five in ZP2 and one in ZP3 by mass spectrometry. Several of these sites are highly conserved in mammals. Remarkably, limited proteolysis by acrosin leads to zona pellucida remodeling rather than degradation. Thus, acrosin affects both sperm binding and mechanical resilience of the zona pellucida, as assessed by microscopy and nanoindentation measurements, respectively. Furthermore, we ascertained potential regulatory effects of acrosin, via activation of latent pro-ovastacin and inactivation of fetuin-B, a tight binding inhibitor of ovastacin. These results offer novel insights into the complex proteolytic network modifying the extracellular matrix of the mouse oocyte, which might apply also to other species.