Roles of estrogen receptors and protooncogenes in uterine cell proliferation.

1)雌激素受体(ER)在小鼠子宫上皮细胞核内的定位利用超薄冰冻切片结合免疫金标记法，研究激素占用和未占用ER的定位，以明确激素结合后ER是否在细胞核内移位。成年去卵巢小鼠注射雌二醇(E_2)或生理盐水，1小时后处死，取子宫作免疫电子显微镜观察。染色质结构和ER定位未见明显变化，分散的和轻度浓缩的染色质中既有空染色质，也有占据的ER，而核仁和高度浓缩的染色质中则没有。这些结果表明ER激活了紧密定位的靶基因，而没有明显的核内移位。2)雌激素诱导的子宫细胞乳铁蛋白(Lf)在子宫细胞中的短暂定位研究了雌激素诱导的分泌蛋白在去卵巢小鼠子宫中的短暂定位，并观察了E2刺激…后Lf在子宫中的定位更多的挑战。LF免疫反应存在于分泌途径中，即在粗面内质网、高尔基体和上皮细胞的分泌小泡中。在注射E_2后6-13小时，核仁中的ER迅速被诱导，并达到高峰。这些发现表明，Lf是早期参与核糖体增殖前合成的基因之一，尽管Lf被认为是一个晚期基因，并被用作上皮细胞分化的标志物。3)激素对小鼠子宫原癌基因的诱导用免疫组织化学和原位杂交的方法检测了小鼠子宫中c-fos和c-jun原癌基因在E2刺激后的细胞类型特异性和时间性表达。注射E2后2小时，c-fos蛋白和c-fos基因在上皮细胞中有瞬时表达。而注射E_2后2-6小时，子宫上皮细胞c-jun蛋白表达降低，而间质和肌层细胞c-jun蛋白表达增加。在血管内皮细胞中，c-fos和c-jun在E_2刺激后1-2小时被一过性诱导。这些结果表明，转录因子AP-1形成的c-fos和c-jun蛋白浓度的快速和短暂变化可能触发子宫上皮细胞的增殖。较少

1) Localization of estrogen receptors (ER) in the nucleus of mouse uterine epitheliumLocalization of hormone occupied and unoccupied ER is investigated to clarify if ER translocate within the nucleus after hormone binding, using ultrathin frozen sections combined with the immunogold technique. Adult ovariectomized mice were injected with estradiol (E2) or saline and killed after 1 hr and the uteri were processed for the immunoelectron microscopy. No apparent changes in the structure of chromatin and ER localization were observed ; both unoccuoied and occupied ER were present in the dispersed and slightly condensed chromatin but not in the nucleolus and highly condensed chromatin. These results suggest that ER activate closely locating target genes without a marked intranuclear translocation.2) Hormonal induction of lactofferin (LF) in the uterine cellsTemporal localizaton of estrogen inducible secretory protein, LF was investigated in the uterus of ovariectomized mouse after E2 stimula … More tion. LF immunoreaction was detectable in the secretory pathways, i.e., in the rough surfaced endoplasmic reticulum, the Golgi apparatus and secretory vesicles of epithelial cells. Furthermore, ER were rapidly induced in the in the nucleolus showing a peak at 6-13 hr after E2 injection. These findings suggest that LF is one of early genes which is involved in the synthesis of ribosomes prior to the proliferation, although LF has been thought as a late gene and used as a maker of cytodifferentiation of epithelium.3) Hormonal induction of protooncogenes in the mouse uterusCell type specific and temporal expression of c-fos and c-jun protooncogenes was examined in the mouse uterus after E2 stimulation employing immunohistochemistry and in situ hybridization. The c-fos protein and mRNA were transiently expressed in the epithelial cells 2 hr after E2 injection. In contrast, E2 injection elicited a decrease of c-jun expression after 2-6 hr in the epithelial cells, however, it was increased in the stromal and myometrial muscle cells. In the endothelial cells of blood vessels, both c-fos and c-jun were transiently induced 1-2 hr after E2 stimulation. These results indicate that rapid and transit changes in the concentration of c-fos and c-jun proteins, which form transcription factor AP-1, may trigger the proliferation of uterine epithelium. Less