Mezger V, Renard J P, Christians E, Morange M
Département de Biologie, Ecole Normale Supérieure, Paris.
Dev Biol. 1994 Oct;165(2):627-38. doi: 10.1006/dbio.1994.1281.
Heat shock gene expression is regulated by highly conserved sequence elements (HSE for "heat shock elements"). Some of heat shock genes display an atypical expression during preimplantation mouse development. We have examined the profile of HSE-binding activities (HSE-BA) in matured ovulated oocytes and during the preimplantation development by gel shift assay and quantified the data by PhosphorImager. In each of our experiments, the F9 embryonal carcinoma cell line that contains both constitutive and heat-induced activity has been used as a control. We determine the number of oocytes or embryos required to get reproducible signals and accurate quantification by PhosphorImager. Oocytes, one-cell, and two-cell embryos respond to heat shock by inducing a strong HSE-BA. At the four-cell stage, no HSE-BA can be induced by heat shock, which suggests that noninducibility of heat shock genes at this stage (when the general mechanism of transcription is well established) might result from a defect in HSF or in the mechanism of HSF activation. A progressive reappearance of the ability to induce HSE-BA by stress is observed between the eight-cell stage and the blastocyst stage, and this parallels the appearance of heat shock gene inducibility. Matured ovulated oocytes and the first cleavage stages of embryos do not contain any HSE-BA at normal temperature but we observed a HSE-BA at normal temperature at the morula stage, which is increased at the blastocyst stage. These data, which, to our knowledge, for the first time describe the profile of a DNA-binding activity during the mouse preimplantation development, could serve as a basis for the study of other transcription factors during early embryogenesis.
热休克基因的表达受高度保守的序列元件（热休克元件，简称HSE）调控。部分热休克基因在小鼠植入前发育过程中呈现非典型表达。我们通过凝胶迁移试验检测了成熟排卵卵母细胞及植入前发育过程中热休克元件结合活性（HSE - BA）的情况，并利用磷光成像仪对数据进行定量分析。在我们的每项实验中，含有组成型和热诱导活性的F9胚胎癌细胞系均用作对照。我们确定了获得可重复信号及通过磷光成像仪进行准确定量所需的卵母细胞或胚胎数量。卵母细胞、单细胞和双细胞胚胎通过诱导强烈的HSE - BA对热休克作出反应。在四细胞阶段，热休克不能诱导HSE - BA，这表明在此阶段（转录的一般机制已充分建立）热休克基因的不可诱导性可能是由于热休克因子（HSF）缺陷或HSF激活机制缺陷所致。在八细胞阶段至囊胚阶段之间观察到应激诱导HSE - BA的能力逐渐恢复，这与热休克基因诱导性的出现相平行。成熟排卵卵母细胞和胚胎的首次分裂阶段在常温下不含有任何HSE - BA，但我们在桑葚胚阶段观察到常温下的HSE - BA，在囊胚阶段其有所增加。据我们所知，这些数据首次描述了小鼠植入前发育过程中DNA结合活性的情况，可为早期胚胎发生过程中其他转录因子的研究提供基础。
