Molecular regulation of gene expression and development of mammalian embryos

在胚胎着床前，从1细胞阶段到囊胚阶段，哺乳动物胚胎的体外发育在合子基因激活（ZGA）发生时被阻止在物种的一个阶段特征。因此，这种发育阻滞可能反映了ZGA在体外培养条件下没有得到很好的调节。最近，活性氧（ROS）参与了这种发育阻滞。降低氧张力和在培养基中添加抗氧化剂，如超氧化物歧化酶或硫氧还蛋白，已被证明对胚胎的体外发育有有益的影响。因此，确定ROS调控早期胚胎发育的机制是很有意义的。近年来，ROS作为调控细胞生长和分化的第二信使，除了氧化应激外，还具有其他功能。在本研究中，我们试图明确氧化还原在早期小鼠胚胎体外发育中的调控作用。结果表明，核因子κ B （NF-kB）的mRNA和蛋白在着床前发育过程中在小鼠胚胎中表达，并且NF-kB在小鼠胚胎的早期1细胞阶段特异性激活，并且NF-kB的激活对于小鼠胚胎超过2细胞阶段的发育至关重要。在生产识别NF-kB特异性活化形式的抗体的实验过程中，我们发现了NF-kB相关的100 kDa蛋白。克隆实验表明，该蛋白在哺乳动物中是一种新的pre-mRNA剪接因子，免疫荧光实验显示，该蛋白在小鼠晚期1细胞胚胎的细胞核中也有阶段特异性积累。在第二个实验中，我们发现一氧化氮（一种自由基分子）对发育起调节作用，特别是对2细胞胚胎向4细胞阶段的过渡和囊胚的形成起调节作用。由此可见，着床前胚胎的发育和基因表达，特别是在ZGA和囊胚形成时期，在氧化还原控制下受到调控。少

In vitro development of mammalian embryos during preimplantation period from the 1-cell to the blastocyst stages is known to be arrested at a stage characteristics for the species when zygotic gene activation (ZGA) occurs. This developmental arrest might, therefore, reflect a ZGA that is not well-regulated under in vitro culture conditions. Recently, involvement of reactive oxygen species (ROS) in this developmental arrest has been noted. Lowering oxygen tension and the addition of anti-oxidants, such as superoxide dismutase or thioredoxin, to the culture medium has been shown to exert a beneficial effect on in vitro development of embryos. Thus, it is much of interest to define the mechanisms by which early embryonic development is regulated by ROS.Recently, it has become clear that ROS have additional functions besides oxidative stress as second messengers for regulation of cell growth and differentiation. In the present studies, attempts were made to define the redox regulation in i … More n vitro development of early mouse embryos. As the results, it was shown that the mRNA and protein of nuclear factor kappa B (NF-kB), a transcription factor that controls the expression of a number of genes under cellular redox potentials, are expressed in mouseembryos during preimplantation development, and NF-kB is stage-specifically activated at early 1-cell stage in mouse embryos, and moreover that the activation of NF-kB is essential for the development of mouse embryos beyond the 2-cell stage. During the course of experiments on the production of antibodies that recognize specifically activated form of NF-kB, we found NF-kB-related 100 kDa protein. Cloning experiments of the protein revealed that it is a novel pre-mRNA splicing factor in mammals, and immunofluorescense experiments revealed that it is also stage -specifically accumulated in the nuclei of late 1-cell mouse embryos. In the second experiments, we found that nitric oxide, a free radical molecule acts as a regulator of development, especially transition of 2-cell embryos to the 4-cell stage and formation of blastocysts. Thus, it is indicated that the development and gene expression of embryos during preimplantation stages, especially at periods of ZGA and blastocyst formation are regulated under redox controls. Less