Xenopus laevis sperm-egg adhesion is regulated by modifications in the sperm receptor and the egg vitelline envelope.
Xenopus laevis sperm-egg adhesion is regulated by modifications in the sperm receptor and the egg vitelline envelope.
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非洲爪蟾精卵粘附是通过精子受体和卵黄膜的修饰来调节的。
DOI：
10.1006/dbio.1997.8607
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
Lennarz,WJ
中科院分区：
文献类型：
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作者：
Tian,J;Gong,H;Thomsen,GH;Lennarz,WJ
在产卵和受精期间发生的非洲爪蟾（Xenopus laevisegg）包膜中的生物化学和超微结构变化已经被彻底研究（赫德里克，J.L.，和Nishihara，D. M.，36，231-247，1991; Larabell，C.一、和钱德勒，D. E、电子显微镜杂志17，294-318，1991）。然而，这些变化与配子相互作用的生物学意义尚不清楚。在目前的研究中，发现包膜的变化直接负责调节精卵粘附，这是受精的初始步骤。由于这些转化，精子只与未受精的卵子结合，而不与卵母细胞或体腔卵结合。此外，它们不与受精卵结合。在我们最近发现的两种结构相关的包膜糖蛋白gp 69/64在受精过程中充当精子受体的背景下，研究了精子结合过程调节的分子和细胞基础（Tian，J. D、龚，H.，埃里森湾H、和Lennarz，W. J.，136，1099-1108，1997）。虽然从卵母细胞或体腔卵包膜分离的纯化的gp 69/64糖蛋白表现出精子结合活性，当这些蛋白质是完整的卵母细胞或体腔卵包膜的一部分时，它们不能被抗gp 69/64抗体或精子接近。在从体腔到卵黄包膜的转换过程中，gp 69/64精子受体暴露在表面上，这与gp 43的蛋白水解裂解和伴随的包膜超微结构改变相关。相反，受精后，当卵的卵黄被膜转化为受精卵的受精被膜时，精子受体的有限蛋白水解裂解导致精子结合活性的丧失。此外，在结构改变的VE顶部形成受精层，为精子结合增加了另一个物理障碍。这些结果提供了新的见解之间的结构-功能的无尾两栖类卵子的包膜组件的关系，并提供进一步的证据支持gp 69/64作为精子受体during X的关键作用。受精卵
The biochemical and ultrastructural changes in the envelope of theXenopus laevisegg that occur during oviposition and fertilization have been thoroughly studied (Hedrick, J. L., and Nishihara, D. M.,Methods Cell Biol.36, 231–247, 1991; Larabell, C. A., and Chandler, D. E.,J. Electron Microsc. Tech.17, 294–318, 1991). However, the biological significance of these changes with respect to gamete interaction has been unclear. In the current study, it was found that changes in the envelope are directly responsible for regulating sperm–egg adhesion, an initial step of fertilization. As a result of these transformations, sperm bind only to unfertilized oviposited eggs, not to oocytes or coelomic eggs. In addition, they do not bind to fertilized eggs. The molecular and cellular basis of the regulation of the sperm binding process was investigated in the context of our recent findings that two structurally related envelope glycoproteins, gp69/64, serve as sperm receptors during fertilization (Tian, J.-D., Gong, H., Thomsen, G. H., and Lennarz, W. J.,J. Cell Biol.136, 1099–1108, 1997). Although the purified gp69/64 glycoproteins isolated from the oocyte or coelomic egg envelopes exhibited sperm binding activity, when these proteins are part of the intact oocyte or coelomic egg envelopes, they are not accessible to either anti-gp69/64 antibodies or to sperm. During the conversion from the coelomic to the vitelline envelope, the gp69/64 sperm receptors become exposed on the surface, an event that correlates with proteolytic cleavage of gp43 and accompanying ultrastructural alterations in the envelope. Conversely, after fertilization, when the vitelline envelope of the egg is converted to the fertilization envelope of the zygote, limited proteolytic cleavage of the sperm receptor results in loss of sperm binding activity. In addition, formation of a fertilization layer on top of the structurally altered VE adds another physical block to sperm binding. These results provide new insights into structure–function relationships between envelope components of the anuran egg, and provide further evidence supporting the key role of gp69/64 as sperm receptors duringX. laevisfertilization.