Studies on physiological functions of ovalbumin and occurrence of neural tube defects due to deprivation of ovalbumin in chick embryo.

卵清蛋白被归类为丝氨酸蛋白酶抑制剂（丝氨酸蛋白酶抑制剂）的同源物，尽管除了它可能是一种营养来源外，对其功能知之甚少。我们已经证明，在胚胎发育过程中，卵白蛋白的天然分子（n -卵白蛋白）被结合到组织中而不降解，同时经历结构变化，形成一种称为“hs -卵白蛋白”的热稳定形式。在这里，为了研究hs -卵清蛋白的必要性，我们使用了一种体外培养方法，通过这种方法，从第7期（神经管开始关闭之前）的鸡蛋中分离出的小鸡胚胎可以正常发育长达24小时。当在培养基中加入抗卵清蛋白多克隆IgG阻断内源性残余卵清蛋白时，分离的胚胎变得不规则，特别是在脑组织中，导致所谓的神经管缺陷（NTD）。NTD诱导的胚胎凋亡和细胞增殖信号减弱。此外，通过在培养基中添加足够量的hs -卵清蛋白，可以挽救igg处理的胚胎，使其在没有NTD的情况下获得正常形态。hs -卵白蛋白比n -卵白蛋白和s -卵白蛋白表现出更高的拯救率，后者是另一种通过体外加热n -卵白蛋白人工产生的热稳定对偶物。这些结果表明卵清蛋白（特别是HS-form）在胚胎器官发生，包括神经管形成中是必不可少的。本研究结果还表明，卵清蛋白缺失的胚胎对TUNEL试剂和PCNA/c-Myc蛋白的原位信号降低，这分别反映了细胞凋亡和细胞增殖的变化。卵清蛋白的剥夺还会影响胚胎的许多基因表达，包括与形态发生有关的分化诱导因子。FGF8和slug的表达明显下降，而BMP4和Pax3的表达增加了3倍以上。然而，这些改变是形态发生异常的原因还是结果尚不清楚。卵清蛋白属于蛇形蛋白超家族，有可能与一些关键的分化诱导因子直接相互作用。少

Ovalbumin has been classified as a homolog of serine protease inhibitor (serpin), although little is known of its function except that it may be a nutrient source. We have shown that, during embryonic development, native molecules of ovalbumin (N-ovalbumin) are incorporated into tissues without degradation while undergoing configurational changes into a heat-stable form called 'HS-ovalbumin.' Here, to investigate the indispensability of HS-ovalbumin, we utilized an in vitro culture method by which chick embryos isolated from eggs at Stage 7 (before the neural tube begins to close) could develop normally for up to 24h. When endogenous, remnant ovalbumin was blocked by adding anti-ovalbumin polyclonal IgG to the medium, the isolated embryos became irregular particularly in brain tissue, resulting in the so-called neural tube deficiency (NTD). The embryos with NTD showed reduced signals for apoptosis and cell proliferation. Moreover, IgG-treated embryos were rescued by adding a sufficient … More amount of HS-ovalbumin to the medium, attaining normal morphologies without NTD. HS-ovalbumin exhibited a higher rescue rate than N-ovalbumin and S-ovalbumin, the latter being another heat-stable counterpart that occurs artificially by heating N-ovalbumin in vitro. These results indicate that ovalbumin (particularly in the HS-form) is essential in embryonic organogenesis, including neural tube formation. present results show also that the ovalbumin-deprived embryos gave decreased in situ signals for TUNEL reagents and for PCNA/c-Myc proteins, which mirror changes in apoptosis and cell proliferation, respectively. Also the ovalbumin deprival affect the embryos on many gene expressions including differentiation-inducing factors related to morphogenesis. Expressions of FGF8 and slug have decreased markedly, whereas those of BMP4 and Pax3 have increased over 3-fold. However, whether each of these alterations is a cause or a result of morphogenetic aberrancy is unclear. Since ovalbumin belongs to the serpin superfamily, there is a possibility that it shows direct interactions with some crucial differentiation-inducing factors. Less