Guzmán Cristina B, Deighton-Collins Sarah, Martinez Angela, Kleerekoper Michael, Zhao Changqing, Benjamins Joyce A, Skafar D F
Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Neuro Endocrinol Lett. 2005 Oct;26(5):526-32.
The mechanism through which estrogen exerts its neuroprotective and anti-neurodegenerative effects in the central nervous system is poorly understood. Human glial cells are implicated in the pathogenesis of Alzheimer's disease and have both alpha and beta estrogen receptors (ER). We developed a glial cell model for ER function using the N20.1 mouse oligodendroglial cell line to evaluate the response of ERalpha and ERbeta to estradiol (E2), a raloxifene analog LY117018 (LY) and 4-hydroxytamoxifen (4OHT).
We tested the ability of exogenous ER to activate transcription in response to ligands (100 nM) using the glial cell line N20.1 in a transient cotransfection assay with an ERalpha or ERbeta expression vector, an ERE-driven reporter and a Renilla luciferase transfection control.
Endogenous ER was not detected in the N20.1 cells by Western immunoblotting. E2 stimulated both ERalpha and ERbeta on both ERE- and AP-1 driven promoters. The transcription stimulation by E2 in the ERalpha and ERbeta through the AP-1driven promoter, though significant, was not of the same magnitude as the stimulation of the ERalpha through the ERE-driven promoter. 4OHT and LY did not show significant transcriptional activation of either the ERalpha or ERbeta, through either the ERE or AP-1 driven promoters. LY, at a 10-fold higher concentration than E2, showed a difference in its antagonist activity on the ERbeta through the AP-1 pathway when compared with the ERE- driven promoter, demonstrating not only promoter specificity, but also receptor specificity.
This is the first description of the activity of 4OHT and LY on estrogen receptors in glia.
雌激素在中枢神经系统中发挥神经保护和抗神经退行性变作用的机制尚不清楚。人类胶质细胞与阿尔茨海默病的发病机制有关，且同时具有α和β雌激素受体（ER）。我们利用N20.1小鼠少突胶质细胞系建立了一个用于ER功能研究的胶质细胞模型，以评估ERα和ERβ对雌二醇（E2）、雷洛昔芬类似物LY117018（LY）和4-羟基他莫昔芬（4OHT）的反应。
我们在瞬时共转染实验中，使用胶质细胞系N20.1、ERα或ERβ表达载体、雌激素反应元件（ERE）驱动的报告基因以及海肾荧光素酶转染对照，测试外源性ER对配体（100 nM）激活转录的能力。
通过蛋白质免疫印迹法在N20.1细胞中未检测到内源性ER。E2在ERE和AP-1驱动的启动子上均刺激了ERα和ERβ。E2通过AP-1驱动的启动子对ERα和ERβ的转录刺激虽然显著，但与通过ERE驱动的启动子对ERα的刺激程度不同。4OHT和LY通过ERE或AP-1驱动的启动子均未显示出对ERα或ERβ的显著转录激活作用。与ERE驱动的启动子相比，LY在浓度比E2高10倍时，通过AP-1途径对ERβ的拮抗活性存在差异，这不仅证明了启动子特异性，还证明了受体特异性。
这是首次描述4OHT和LY对胶质细胞中雌激素受体的活性。
