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物(Serpin)的同系物，尽管人们对其功能知之甚少，但它可能是一种营养来源。我们已经证明，在胚胎发育过程中，天然的卵清蛋白分子(N-卵清蛋白)在经历构型变化时不会降解地被整合到组织中，形成一种称为HS-卵蛋白的热稳定形式。在这里，为了探讨HS-卵清蛋白的必要性，我们利用了一种体外培养方法，通过这种方法，从7期(神经管开始关闭之前)的鸡蛋中分离出的鸡胚胎可以正常发育到24小时。当在培养液中加入抗卵清蛋白多克隆抗体阻断内源性残留卵白蛋白时，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患者胚胎的细胞凋亡和细胞增殖信号减少。此外，加入足够的…可以挽救免疫球蛋白处理过的胚胎。更多的HS-卵清蛋白进入培养液，在没有NTD的情况下达到正常的形态。HS-卵白蛋白具有比N-卵白蛋白和S卵白蛋白更高的救援率，后者是人工加热N-卵白蛋白而产生的另一种体外热稳定的类似物。这些结果表明，卵清蛋白(尤其是HS形式)在胚胎器官发生中是必不可少的，包括神经管的形成。目前的结果还表明，去卵白蛋白胚胎的原位TUNEL试剂和增殖细胞核抗原/c-Myc蛋白信号减弱，分别反映了细胞凋亡和细胞增殖的变化。此外，卵清蛋白的剥夺还会影响胚胎的许多基因表达，包括与形态发生相关的分化诱导因子。FGF8和Slug的表达明显减少，而BMP4和Pax3的表达增加了3倍以上。然而，这些改变中的每一种都是形态发生异常的原因还是结果尚不清楚。由于卵清蛋白属于丝氨酸超家族，因此它有可能与一些关键的分化诱导因子直接相互作用。较少

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