Leber hereditary optic neuropathy mtDNA mutations disrupt glutamate transport in cybrid cell lines
Leber hereditary optic neuropathy mtDNA mutations disrupt glutamate transport in cybrid cell lines
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DOI：
10.1093/brain/awh258
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发表时间：
2004-10-01
期刊：
影响因子：
14.5
通讯作者：
Ferrarese, C
中科院分区：
文献类型：
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作者：
Beretta, S;Mattavelli, L;Ferrarese, C
Leber遗传性视神经病变（LHON）是由线粒体基因组（mtDNA）中的点突变引起的导致视神经萎缩的视网膜神经节细胞变性的母系遗传形式。三种致病性突变（位置11778/ND 4、3460/ND 1和14484/ND 6）占LHON病例的大多数，并且它们影响编码线粒体复合物I的不同亚基的基因。视网膜神经节细胞和视神经的兴奋性毒性损伤先前已被假设，特别是考虑到这种神经细胞类型对谷氨酸毒性的高敏感性。从6名不相关的LHON患者中产生的骨肉瘤源性胞质杂交体（胞质杂交体），每个致病性突变的两个细胞系，与从3名健康对照中获得的胞质杂交体进行比较。分子和生化分析表明，兴奋性氨基酸转运蛋白1（EAAT 1）/GLAST是在这个细胞模型中最活跃的谷氨酸转运蛋白。谷氨酸摄取最大速率在所有LHON胞质杂交体中与对照胞质杂交体相比显著降低。这种减少与线粒体产生活性氧的程度相关，这在LHON胞质杂种中增强。我们的研究结果支持这一假设，即遗传决定的线粒体功能障碍LHON患者导致受损的EAAT 1谷氨酸转运蛋白的活性。这一观察结果是特别相关的，因为EAAT 1是视网膜内层谷氨酸清除的主要手段，这可以防止视网膜神经节细胞因兴奋性毒性而受损。
Leber hereditary optic neuropathy (LHON) is a maternally inherited form of retinal ganglion cell degeneration leading to optic atrophy which is caused by point mutations in the mitochondrial genome (mtDNA). Three pathogenic mutations (positions 11778/ND4, 3460/ND1 and 14484/ND6) account for the majority of LHON cases and they affect genes that encode for different subunits of mitochondrial complex I. Excitotoxic injury to retinal ganglion cells and the optic nerve has been previously hypothesized, especially given the high susceptibility of this neural cell type to glutamate toxicity. Osteosarcoma-derived cytoplasmic hybrids (cybrids) generated from six unrelated LHON patients, two cell lines for each pathogenic mutation, were compared with cybrids obtained from three healthy controls. Molecular and biochemical analyses showed that excitatory amino acid transporter 1 (EAAT1)/GLAST is the most active glutamate transporter in this cellular model. The glutamate uptake maximal velocity was significantly reduced in all LHON cybrids compared with control cybrids. This reduction was correlated in a mutation-specific fashion with the degree of mitochondrial production of reactive oxygen species, which is enhanced in LHON cybrids. Our findings support the hypothesis that the genetically determined mitochondrial dysfunction in LHON patients leads to impaired activity of the EAAT1 glutamate transporter. This observation is particularly relevant since EAAT1 is the major means of glutamate removal in the inner retina and this prevents retinal ganglion cells being damaged as a result of excitotoxicity.