Alexander disease mutant glial fibrillary acidic protein compromises glutamate transport in astrocytes.
Alexander disease mutant glial fibrillary acidic protein compromises glutamate transport in astrocytes.
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DOI：
10.1097/nen.0b013e3181d3cb52
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发表时间：
2010-04
影响因子：
3.2
通讯作者：
Goldman JE
中科院分区：
文献类型：
--
作者：
Tian R;Wu X;Hagemann TL;Sosunov AA;Messing A;McKhann GM;Goldman JE
亚历山大病（AxD）是由胶质细胞酸性蛋白基因杂合突变引起的脑白质营养不良，胶质细胞酸性蛋白是星形胶质细胞表达的中间丝蛋白。该突变导致星形胶质细胞内的蛋白质聚集突出;还存在髓鞘和少突胶质细胞的损失以及神经元变性。我们发现，免疫组化染色谷氨酸转运蛋白1，主要在星形胶质细胞表达的主要脑谷氨酸转运蛋白表明在婴儿AxD患者的大脑皮层水平下降。AxD基因敲入小鼠模型也显示海马中谷氨酸转运蛋白1的显著减少。为了在细胞水平上探索这种现象，在培养的星形胶质细胞中过表达野生型和R239C突变型胶质细胞酸性蛋白（最常见的突变）。Western印迹和全细胞膜片钳记录表明，R239C星形胶质细胞表现出显着降低谷氨酸转运蛋白1的蛋白水平，这导致衰减或废除谷氨酸诱导的内向转运体电流。与R239C星形胶质细胞共培养的神经元在谷氨酸激发后表现出增加的死亡。这些结果表明，异常星形胶质细胞减少谷氨酸摄取，这可能在AxD的神经元和少突胶质细胞损伤和死亡的发病机制中发挥重要作用。
Alexander disease (AxD) is a leukodystrophy caused by heterozygous mutations in the gene for glial fibrillary acidic protein, an intermediate filament protein expressed by astrocytes. The mutation causes prominent protein aggregates inside astrocytes; there is also loss of myelin and oligodendrocytes and neuronal degeneration. We show that immunohistochemical staining for glutamate transporter 1, the major brain glutamate transporter expressed primarily in astrocytes suggests decreased levels in the hippocampi of infantile AxD patients. A knock-in mouse model of AxD also shows significant reduction of glutamate transporter 1 in the hippocampus. To explore this phenomenon at the cellular level, wild-type and R239C mutant glial fibrillary acidic proteins (the most common mutation) were overexpressed in astrocytes in culture. Western blotting and whole-cell patch clamp recordings demonstrated that the R239C astrocytes exhibited markedly reduced glutamate transporter 1 protein levels; this resulted in attenuated or abolished glutamate-induced inward transporter current. Neurons cocultured with the R239C astrocytes exhibited increased death after glutamate challenge. These results indicate that aberrant astrocytes have decreased glutamate uptake, which may play an important role in the pathogenesis of neuronal and oligodendrocyte injury and death in AxD.