Division of Environmental Genetics and Molecular Toxicology, Department of Environmental Health, University of Cincinnati Medical Center, Cincinnati, OH 45267, United States.
Mol Cell Endocrinol. 2012 Jul 6;358(1):27-35. doi: 10.1016/j.mce.2012.02.012. Epub 2012 Feb 19.
Multiple phosphorylation sites on the human estrogen receptor (hER)α were identified and shown to influence mammary carcinogenesis. In contrast, functional phosphorylation sites of hERβ have yet to be experimentally identified and validated. Here, using mass spectrometry, we uncovered three serines (S75, S87, and S105) in the N-terminus of hERβ as targets of ERK1/2 and p38 kinases. We raised a specific antibody against phosphorylated S105 (pS105) and demonstrated that this site was endogenously phosphorylated in MDA-MB-231 and BT-474 cells. A phospho-mimetic mutant generated from hERβ1 was found to exhibit higher transactivation activity than hERβ1. Ectopic expression of this mutant inhibited cell migration and invasion, but did not affect cell growth and cell-cycle progression in these cell models. In breast cancer specimens, pS105-hERβ immunoreactivity was detected with a higher prevalence and intensity than that of hERβ1. These results underscore the functional importance of the first experimentally identified hERβ-phosphorylation site in breast cancer.
人类雌激素受体（hER）α上的多个磷酸化位点已被鉴定出来，并被证明会影响乳腺癌的发生。相比之下，hERβ的功能磷酸化位点尚未经过实验鉴定和验证。在这里，我们使用质谱技术在 hERβ的 N 端发现了三个丝氨酸（S75、S87 和 S105），它们是 ERK1/2 和 p38 激酶的作用靶点。我们针对磷酸化 S105（pS105）产生了一种特异性抗体，并证明该位点在 MDA-MB-231 和 BT-474 细胞中是内源性磷酸化的。从 hERβ1 生成的磷酸模拟突变体被发现具有比 hERβ1 更高的转录激活活性。在这些细胞模型中，该突变体的异位表达抑制了细胞迁移和侵袭，但不影响细胞生长和细胞周期进程。在乳腺癌标本中，pS105-hERβ 的免疫反应性比 hERβ1 更为普遍和强烈。这些结果强调了第一个在乳腺癌中实验鉴定的 hERβ 磷酸化位点的功能重要性。
