Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Donghu Experimental Station of Lake Ecosystems, State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, 430072, China.
Biochimie. 2021 Feb;181:134-144. doi: 10.1016/j.biochi.2020.12.007. Epub 2020 Dec 14.
Fertilization is an essential process that fundamentally impacts fitness. An egg changes dramatically after fertilization mediating the beginning of life, which mainly includes the transformation of the egg envelope via hardening, which is thought to be due to complex reactions involved in the conversion of cellular and molecular. This review highlights the mechanisms of egg envelope hardening in teleost fish. We conclude that the egg envelope hardening might be carried out in two steps. (a) A metalloprotease (alveolin) hydrolyzes the N-terminal proline-glutamine (Pro-Gln) region of zona pellucida (ZP) 1 and (b) triggers intermolecular cross-linking to ZP3 catalyzed by transglutaminase (TGase). The post-fertilization hardening of the egg envelope is an evolutionarily conserved phenomenon across species. We discuss the biochemical function and interaction of some factors reported to be essential to egg envelope hardening in mammalian and nonmammalian species, including metalloprotease, TGase, peroxidase/ovoperoxidase, and other factors (carbohydrate moieties, zinc and Larp6 proteins), and the relevant data suggest that egg envelope hardening is crucial to block polyspermy in internal fertilization, in addition to protecting the developing embryo from mechanical shock and preventing bacterial infection in external fertilization. Increased knowledge of the processes of egg envelope hardening and fertilization is likely to make a remarkable contribution to reproduction and aquaculture.
受精是一个基本过程，从根本上影响着生物的适应性。受精后，卵子会发生剧烈变化，从而开启生命的历程，这主要包括卵膜的硬化转变，其被认为是由于细胞和分子转化过程中涉及的复杂反应所致。本综述重点介绍了硬骨鱼类卵膜硬化的机制。我们的结论是，卵膜硬化可能分两步进行。（a）金属蛋白酶（肺泡蛋白）水解卵透明带（ZP）1 的 N 端脯氨酸-谷氨酰胺（Pro-Gln）区域，（b）由转谷氨酰胺酶（TGase）触发 ZP3 分子间交联。受精后卵膜的硬化是跨物种进化保守的现象。我们讨论了一些被报道在哺乳动物和非哺乳动物物种中对卵膜硬化至关重要的因素的生化功能和相互作用，包括金属蛋白酶、TGase、过氧化物酶/卵过氧化物酶和其他因素（碳水化合物部分、锌和 Larp6 蛋白），相关数据表明，卵膜硬化对于阻止内部受精的多精入卵、保护胚胎免受机械冲击以及防止外部受精中的细菌感染至关重要。对卵膜硬化和受精过程的深入了解可能会对生殖和水产养殖做出显著贡献。
