The cystine‐glutamate exchanger (xCT, Slc7a11) is expressed in significant concentrations in a subpopulation of astrocytes in the mouse brain,Glia

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The cystine‐glutamate exchanger (xCT, Slc7a11) is expressed in significant concentrations in a subpopulation of astrocytes in the mouse brain
Glia ( IF 5.4 ) Pub Date : 2018-01-19 , DOI: 10.1002/glia.23294
Sigrid Ottestad-Hansen ₁ , Qiu Xiang Hu ₁ , Virgine Veronique Follin-Arbelet ₁ , Eduard Bentea ₂ , Hideyo Sato ₃ , Ann Massie ₂ , Yun Zhou ₁ , Niels Christian Danbolt ₁

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The cystine‐glutamate exchanger (xCT) promotes glutathione synthesis by catalyzing cystine uptake and glutamate release. The released glutamate may modulate normal neural signaling and contribute to excitotoxicity in pathological situations. Uncertainty, however, remains as neither the expression levels nor the distribution of xCT have been unambiguously determined. In fact, xCT has been reported in astrocytes, neurons, oligodendrocytes and microglia, but most of the information derives from cell cultures. Here, we show by immunohistochemistry and by Western blotting that xCT is widely expressed in the central nervous system of both sexes. The labeling specificity was validated using tissue from xCT knockout mice as controls. Astrocytes were selectively labeled, but showed greatly varying labeling intensities. This astroglial heterogeneity resulted in an astrocyte domain‐like labeling pattern. Strong xCT labeling was also found in the leptomeninges, along some blood vessels, in selected circumventricular organs and in a subpopulation of tanycytes residing the lateral walls of the ventral third ventricle. Neurons, oligodendrocytes and resting microglia, as well as reactive microglia induced by glutamine synthetase deficiency, were unlabeled. The concentration of xCT protein in hippocampus was compared with that of the EAAT3 glutamate transporter by immunoblotting using a chimeric xCT‐EAAT3 protein to normalize xCT and EAAT3 labeling intensities. The immunoblots suggested an xCT/EAAT3 ratio close to one (0.75 ± 0.07; average ± SEM; n = 4) in adult C57BL6 mice. Conclusions: xCT is present in select blood/brain/CSF interface areas and in an astrocyte subpopulation, in sufficient quantities to support the notion that system $urn:x-wiley:08941491:media:glia23294:glia23294-math-0002$ provides physiologically relevant transport activity.

中文翻译：

胱氨酸-谷氨酸交换子（xCT，Slc7a11）在小鼠脑星形胶质细胞亚群中以高浓度表达

胱氨酸-谷氨酸交换剂（xCT）通过催化胱氨酸的摄取和谷氨酸的释放来促进谷胱甘肽的合成。释放的谷氨酸可能调节正常的神经信号传导，并在病理情况下导致兴奋性毒性。但是，不确定性仍然存在，因为尚未明确确定xCT的表达水平或分布。实际上，已经在星形胶质细胞，神经元，少突胶质细胞和小胶质细胞中报道了xCT，但是大多数信息来自细胞培养。在这里，我们通过免疫组织化学和蛋白质印迹显示xCT在男女的中枢神经系统中广泛表达。使用来自xCT基因敲除小鼠的组织作为对照，验证了标记特异性。星形胶质细胞被选择性标记，但显示出很大的标记强度。这种星形胶质细胞的异质性导致了星形胶质细胞域样标记模式。在软脑膜，一些血管，选定的室间隔器官和位于腹侧第三脑室侧壁的单核细胞亚群中也发现了强大的xCT标记。神经元，少突胶质细胞和静息的小胶质细胞，以及由谷氨酰胺合成酶缺乏症诱导的反应性小胶质细胞均未标记。通过使用嵌合xCT-EAAT3蛋白进行免疫印迹以标准化xCT和EAAT3标记强度，将海马中xCT蛋白的浓度与EAAT3谷氨酸转运蛋白的浓度进行了比较。免疫印迹表明xCT / EAAT3比率接近1（0.75±0.07;平均值± 在选定的室室器官和位于腹侧第三脑室侧壁的单核细胞亚群中。神经元，少突胶质细胞和静息的小胶质细胞，以及由谷氨酰胺合成酶缺乏症诱导的反应性小胶质细胞均未标记。通过使用嵌合xCT-EAAT3蛋白进行免疫印迹以标准化xCT和EAAT3标记强度，将海马中xCT蛋白的浓度与EAAT3谷氨酸转运蛋白的浓度进行了比较。免疫印迹表明xCT / EAAT3比率接近1（0.75±0.07;平均值± 在选定的室室器官和位于腹侧第三脑室侧壁的单核细胞亚群中。神经元，少突胶质细胞和静息的小胶质细胞，以及由谷氨酰胺合成酶缺乏症诱导的反应性小胶质细胞均未标记。通过使用嵌合xCT-EAAT3蛋白进行免疫印迹以标准化xCT和EAAT3标记强度，将海马中xCT蛋白的浓度与EAAT3谷氨酸转运蛋白的浓度进行了比较。免疫印迹表明xCT / EAAT3比率接近1（0.75±0.07;平均值± 通过使用嵌合xCT-EAAT3蛋白进行免疫印迹以标准化xCT和EAAT3标记强度，将海马中xCT蛋白的浓度与EAAT3谷氨酸转运蛋白的浓度进行了比较。免疫印迹提示xCT / EAAT3比率接近1（0.75±0.07;平均值± 通过使用嵌合xCT-EAAT3蛋白进行免疫印迹以标准化xCT和EAAT3标记强度，将海马中xCT蛋白的浓度与EAAT3谷氨酸转运蛋白的浓度进行了比较。免疫印迹表明xCT / EAAT3比率接近1（0.75±0.07;平均值± 扫描电镜; n = 4）在成年C57BL6小鼠中。结论：xCT存在于特定的血液/脑/ CSF界面区域和星形胶质细胞亚群中，其数量足以支持系统 $骨灰盒：x-wiley：08941491：media：glia23294：glia23294-math-0002$ 提供生理相关运输活性的观点。

更新日期：2018-01-19

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