Mezger V, Bensaude O, Morange M
Laboratoire de Biologie Moléculaire du Stress, Institut Pasteur, Paris, France.
Mol Cell Biol. 1989 Sep;9(9):3888-96. doi: 10.1128/mcb.9.9.3888-3896.1989.
In contrast to differentiated somatic cells, mouse embryonal carcinoma (EC) cell lines spontaneously express high levels of major members of the heat shock protein (HSP) family. In addition, some EC cell lines (noninducible) are not able to induce HSP gene transcription and HSP synthesis after a stress. However, after in vitro differentiation, constitutive HSP expression decreases and the differentiated derivatives become able to induce HSP gene transcription after a stress. These cells were tested by gel shift assays for the presence of an activity able to bind the heat shock element (HSE) before and after a stress. Control fibroblasts grown at 37 degrees C did not contain significant levels of HSE-binding activity, but heat shock dramatically increased the level of HSE-binding activity. In contrast to control fibroblasts, all EC cells contained significant levels of HSE-binding activity at 37 degrees C. In the inducible EC cell line F9, as in fibroblasts, heat shock strongly increased the level of HSE-binding activity. In the noninducible EC cells, however, HSE-binding activity markedly decreased upon heat shock. During in vitro differentiation of the noninducible cell line PCC7-S-1009, the constitutive HSE-binding activity found at 37 degrees C disappeared and heat induction of the HSE-binding activity appeared. Therefore, a good correlation exists between the high spontaneous expression of some members of the HSP family and the constitutive level of HSE-binding activity in EC cells at 37 degrees C. Heat induction of HSP gene transcription correlates with a strong increase in HSE-binding activity, whereas a deficiency in heat induction of HSP gene transcription is associated with a loss of HSE-binding activity upon heat shock.
与分化的体细胞不同，小鼠胚胎癌细胞系会自发高水平表达热休克蛋白（HSP）家族的主要成员。此外，一些胚胎癌细胞系（非诱导型）在应激后无法诱导HSP基因转录和HSP合成。然而，在体外分化后，组成型HSP表达降低，分化后的衍生物在应激后能够诱导HSP基因转录。通过凝胶迁移试验检测了这些细胞在应激前后是否存在能够结合热休克元件（HSE）的活性。在37℃培养的对照成纤维细胞不含显著水平的HSE结合活性，但热休克显著增加了HSE结合活性水平。与对照成纤维细胞不同，所有胚胎癌细胞在37℃时都含有显著水平的HSE结合活性。在可诱导的胚胎癌细胞系F9中，与成纤维细胞一样，热休克强烈增加了HSE结合活性水平。然而，在非诱导型胚胎癌细胞中，热休克后HSE结合活性显著降低。在非诱导型细胞系PCC7-S-1009的体外分化过程中，在37℃时发现的组成型HSE结合活性消失，热诱导的HSE结合活性出现。因此，HSP家族某些成员的高自发表达与胚胎癌细胞在37℃时HSE结合活性的组成型水平之间存在良好的相关性。HSP基因转录的热诱导与HSE结合活性的强烈增加相关，而HSP基因转录热诱导的缺陷与热休克后HSE结合活性的丧失相关。
