Critical Role of the Cortical Alveolus Protease Alveolin in Chorion Hardening In Vivo at Medaka Fertilization.
Critical Role of the Cortical Alveolus Protease Alveolin in Chorion Hardening In Vivo at Medaka Fertilization.
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皮质肺泡蛋白酶肺泡在青鳉受精体内绒毛膜硬化中的关键作用。
DOI：
10.3390/biom13010146
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发表时间：
2023-01-10
期刊：
影响因子：
5.5
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中科院分区：
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肺泡蛋白是一种皮质肺泡蛋白酶，在受精时在卵周间隙 (PVS) 中分泌，作用于绒毛膜。已知纯化的肺泡蛋白可通过处理主要绒毛膜成分 B 透明带 (ZPB) 来诱导绒毛膜硬化。然而，肺泡蛋白的体内功能仍不清楚。因此，在本研究中，使用青鳉Oryzias latipes 来研究肺泡素效率 (Alv−/−) 在生物体水平上的影响。 Alv−/− 受精卵在机械上是脆弱的；然而，只要在孵化前小心处理，它们就能正常发育并留下后代。机械压力测试表明，Alv−/− 受精卵比野生型卵脆弱六倍。由于 PVS 增大，它们的尺寸增大了 35%，厚度减小了 34%，并且甚至可以渗透 10 kDa FITC-葡聚糖。这些结果与透射电子显微镜观察到的 Alv−/− 绒毛膜内层外围高度多孔的现象一致。在绒毛膜硬化中，肺泡介导的 ZPB 加工和转谷氨酰胺酶 (TGase) 介导的绒毛膜成分交联是关键步骤。这项研究首次表明肺泡蛋白还与 ZPB 一起加工 TGase，这极大地促进了交联。因此，肺泡蛋白被认为是体内绒毛膜硬化的主要触发因素。此外，在平衡盐溶液中受精可以部分改善在水中受精的 Alv−/− 卵的受损绒毛膜硬化，这可能是通过一种不依赖于肺泡蛋白的机制。
Alveolin is a cortical alveolus proteinase that is secreted in the perivitelline space (PVS) at fertilization to act on the chorion. Purified alveolin is known to induce chorion hardening in vitro by processing zona pellucida B (ZPB), a major chorion component. However, in vivo function of alveolin remains unclear; thus, in this study, the effects of alveolin efficiency (Alv−/−) at the organism level were investigated using the medaka, Oryzias latipes. The Alv−/− fertilized eggs were mechanically fragile; however, they developed normally and left offspring as long as they were carefully handled before hatching. A mechanical press test showed that the Alv−/− fertilized eggs were six times more fragile than the wild-type eggs. They were 35% larger owing to the enlarged PVS, 34% thinner, and permeable to even 10 kDa FITC-dextran. These results are consistent with the transmission electron microscopy observation that the periphery of the inner layers was highly porous in the Alv−/− chorion. In chorion hardening, the alveolin-mediated processing of ZPB and the transglutaminase (TGase)-mediated crosslinking of chorion components are the key steps. This study was the first to show that alveolin also processed TGase concomitantly with ZPB, which greatly facilitated the crosslinking. Thus, alveolin was concluded to be the primary trigger for chorion hardening in vivo. Furthermore, fertilization in a balanced salt solution could partially improve the impaired chorion hardening of the Alv−/− eggs fertilized in water, probably through an alveolin-independent mechanism.