Maneix Laure, Antonson Per, Humire Patricia, Rochel-Maia Sabrina, Castañeda Jessica, Omoto Yoko, Kim Hyun-Jin, Warner Margaret, Gustafsson Jan-Åke
Center for Nuclear Receptors and Cell Signaling, Department of Biology and Biochemistry, University of Houston, Houston, TX 77204; and.
Center for Biosciences, Department of Biosciences and Nutrition, Karolinska Institutet, Novum, 14186 Stockholm, Sweden.
Proc Natl Acad Sci U S A. 2015 Apr 21;112(16):5135-40. doi: 10.1073/pnas.1504944112. Epub 2015 Apr 6.
In 1998, an estrogen receptor β (ERβ) knockout (KO) mouse was created by interrupting the gene at the DNA binding domain (DBD) with a neocassette. The mutant females were subfertile and there were abnormalities in the brain, prostate, lung, colon, and immune system. In 2008, another ERβ mutant mouse was generated by deleting ERβ exon 3 which encodes the first zinc finger in the DBD. The female mice of this strain were unable to ovulate but were otherwise normal. The differences in the phenotypes of the two KO strains, have led to questions about the physiological function of ERβ. In the present study, we created an ERβ exon 3-deleted mouse (ERβ-Δex3) and confirmed that the only observable defect was anovulation. Despite the two in-frame stop codons introduced by splicing between exons 2 and 4, an ERβ protein was expressed in nuclei of prostate epithelial cells. Using two different anti-ERβ antibodies, we showed that an in-frame ligand binding domain and C terminus were present in the ERβ-Δex3 protein. Moreover, with nuclear extracts from ERβ-Δex3 prostates, there was an ERβ-dependent retardation of migration of activator protein-1 response elements in EMSA. Unlike the original knockout mouse, expression of Ki67, androgen receptor, and Dachshund-1 in prostate epithelium was not altered in the ERβ-Δex3 mouse. We conclude that very little of ERβ transcriptional activity depends on binding to classical estrogen response elements (EREs).
1998年，通过用新盒式结构在DNA结合域（DBD）处中断基因，创建了一种雌激素受体β（ERβ）基因敲除（KO）小鼠。突变雌性小鼠生育力低下，并且在大脑、前列腺、肺、结肠和免疫系统中存在异常。2008年，通过缺失编码DBD中第一个锌指的ERβ外显子3，产生了另一种ERβ突变小鼠。该品系的雌性小鼠无法排卵，但其他方面正常。两种基因敲除品系表型的差异引发了关于ERβ生理功能的疑问。在本研究中，我们创建了一种缺失ERβ外显子3的小鼠（ERβ-Δex3），并证实唯一可观察到的缺陷是无排卵。尽管外显子2和4之间的剪接引入了两个框内终止密码子，但在前列腺上皮细胞核中表达了一种ERβ蛋白。使用两种不同的抗ERβ抗体，我们表明ERβ-Δex3蛋白中存在框内配体结合域和C末端。此外，用ERβ-Δex3前列腺的核提取物进行电泳迁移率变动分析（EMSA）时，激活蛋白-1反应元件的迁移存在ERβ依赖性阻滞。与原始基因敲除小鼠不同，ERβ-Δex3小鼠前列腺上皮中Ki67、雄激素受体和腊肠犬相关转录因子1的表达没有改变。我们得出结论，ERβ的转录活性很少依赖于与经典雌激素反应元件（ERE）的结合。
