Sinkevicius Kerstin W, Burdette Joanna E, Woloszyn Karolina, Hewitt Sylvia C, Hamilton Katherine, Sugg Sonia L, Temple Karla A, Wondisford Fredric E, Korach Kenneth S, Woodruff Teresa K, Greene Geoffrey L
The Ben May Department for Cancer Research, The University of Chicago, Chicago, Illinois 60637, USA.
Endocrinology. 2008 Jun;149(6):2970-9. doi: 10.1210/en.2007-1526. Epub 2008 Mar 13.
Estrogen-nonresponsive estrogen receptor-alpha (ERalpha) knock-in (ENERKI) mice were generated to distinguish between ligand-induced and ligand-independent ER-alpha actions in vivo. These mice have a mutation [glycine 525 to leucine (G525L)] in the ligand-binding domain of ERalpha, which significantly reduces ERalpha interaction with and response to endogenous estrogens, whereas not affecting growth factor activation of ligand-independent pathways. ENERKI mice had hypoplastic uterine tissues and rudimentary mammary gland ductal trees. Females were infertile due to anovulation, and their ovaries contained hemorrhagic cystic follicles because of chronically elevated levels of LH. The ENERKI phenotype confirmed that ligand-induced activation of ERalpha is crucial in the female reproductive tract and mammary gland development. Growth factor treatments induced uterine epithelial proliferation in ovariectomized ENERKI females, directly demonstrating that ERalpha ligand-independent pathways were active. In addition, the synthetic ERalpha selective agonist propyl pyrazole triol (PPT) and ER agonist diethylstilbestrol (DES) were still able to activate ligand-induced G525L ERalpha pathways in vitro. PPT treatments initiated at puberty stimulated ENERKI uterine development, whereas neonatal treatments were needed to restore mammary gland ductal elongation, indicating that neonatal ligand-induced ERalpha activation may prime mammary ducts to become more responsive to estrogens in adult tissues. This is a useful model for in vivo evaluation of ligand-induced ERalpha pathways and temporal patterns of response. DES did not stimulate an ENERKI uterotrophic response. Because ERbeta may modulate ERalpha activation and have an antiproliferative function in the uterus, we hypothesize that ENERKI animals were particularly sensitive to DES-induced inhibition of ERalpha due to up-regulated uterine ERbeta levels.
为了在体内区分雌激素诱导的和非雌激素依赖的雌激素受体α（ERα）作用，构建了雌激素无反应性雌激素受体α基因敲入（ENERKI）小鼠。这些小鼠的ERα配体结合域发生了一个突变[甘氨酸525突变为亮氨酸（G525L）]，这显著降低了ERα与内源性雌激素的相互作用及反应，而不影响非配体依赖途径的生长因子激活。ENERKI小鼠的子宫组织发育不全，乳腺导管树发育不良。雌性小鼠因无排卵而不育，且由于促黄体生成素（LH）水平长期升高，其卵巢含有出血性囊性卵泡。ENERKI小鼠的表型证实，雌激素诱导的ERα激活在雌性生殖道和乳腺发育中至关重要。生长因子处理可诱导去卵巢的ENERKI雌性小鼠子宫上皮细胞增殖，直接证明了ERα非配体依赖途径是活跃的。此外，合成的ERα选择性激动剂丙基吡唑三醇（PPT）和雌激素激动剂己烯雌酚（DES）在体外仍能激活雌激素诱导的G525L ERα途径。青春期开始的PPT处理可刺激ENERKI小鼠子宫发育，而恢复乳腺导管伸长则需要新生儿期处理，这表明新生儿期雌激素诱导的ERα激活可能使乳腺导管在成年组织中对雌激素更敏感。这是一个用于体内评估雌激素诱导的ERα途径及反应时间模式的有用模型。DES未刺激ENERKI小鼠子宫增重反应。由于ERβ可能调节ERα激活并在子宫中具有抗增殖功能，我们推测ENERKI动物对DES诱导的ERα抑制特别敏感是由于子宫ERβ水平上调。
