Studies of the hormone-dependent expression of conalbumin gene

蛋清蛋白是一种蛋清蛋白，在鸡输卵管中由雌激素诱导产生。包括雌激素在内的类固醇激素与靶细胞中的特定受体结合，然后类固醇受体复合体通过与核染色质结合而发挥刺激作用。本研究对核中组蛋白乙酰化作用进行了研究。雌性雏鸡用雌激素刺激14~19天，然后拔除输卵管。用~(3 H)H-乙酸钠孵育组织，使核组蛋白乙酰化。用羟基磷灰石柱层析法分析鸡输卵管染色质乙酰化组蛋白的释放。随着氯化钠浓度的增加，乙酰化组蛋白被从羟基磷灰石结合的染色质中洗脱出来，这取决于它们从核小体DNA中的释放。酸性尿素凝胶电泳法显示，低乙酰化组蛋白H4在较低的氯化钠浓度下洗脱，说明高乙酰化组蛋白H4在核小体中的稳定性降低。这些数据有力地表明，组蛋白乙酰化在鸡输卵管基因表达中起着重要作用。

Conalbumin, an egg white protein, is induced in the chick oviduct by the administration of estrogen. Steroid hormones including estrogen bind to specific receptors in target cells, then the steroid-receptor complexes exert the stimulation effects through their binding to nuclear chromatin. In this study, the role of nuclear histone acetylation was studied. Female chicks were stimulated for 14 to 19 days with estrogen, then oviducts were removed. Nuclear histone was acetylated by incubating the tissue with ^3H-sodium acetate. The release of acetylated histones from chick oviduct chromatin was analyzed by hydroxylapatite column chromatography. By raising of the NaCl concentration, acetylated histones were eluted from hydroxylapatite-bound chromatin depending on their release from nucleosomal DNA. Electrophoresis on acid-urea gel showed that hypoeracetylated forms of histone H4 were eluted at a lower NaCl concentration than non-acetylated or hypoacetylated H4, indicating that hyperacetylated H4 has decreased stability in nucleosomes. These data strongly suggest that histone acetylation has an important role on the gene expression in the chick oviduct.