α-synuclein overexpression increases cytosolic catecholamine concentration
α-synuclein overexpression increases cytosolic catecholamine concentration
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DOI：
10.1523/jneurosci.0519-06.2006
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发表时间：
2006-09-06
影响因子：
5.3
通讯作者：
Sulzer, David
中科院分区：
文献类型：
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作者：
Mosharov, Eugene V.;Staal, Roland G. W.;Sulzer, David
多巴胺稳态的失调和递质胞质水平的升高被认为是帕金森病中儿茶酚胺能神经元脆弱性的基础。由于几种已知的α-突触核蛋白突变或野生型（WT）蛋白的过度表达导致家族性帕金森病，我们研究了α-突触核蛋白发病机制和多巴胺稳态之间可能的联系。从过表达A30 P α-突触核蛋白的转基因小鼠中分离的嗜铬细胞显示出显著增加的胞质儿茶酚胺水平，如通过细胞内贴片电化学测量的，而过表达WT蛋白的细胞和来自敲除动物的细胞与对照组没有差异。同样，儿茶酚浓度较高的L-DOPA-处理过的PC 12细胞过表达A30 P或A53 T相比，那些表达WT α-突触核蛋白，虽然细胞的能力，以保持低的胞质多巴胺水平L-DOPA挑战后显着抑制蛋白质。我们还发现，与低微摩尔浓度的WT，A30 P，或A53 T α-突触核蛋白孵育抑制ATP依赖性的维持pH梯度在孤立的嗜铬囊泡和WT蛋白是显着较低的效力在诱导质子泄漏。总之，我们证明了不同类型的α-突触核蛋白的过表达破坏囊泡pH值，并导致细胞溶质儿茶酚类物质的水平显着增加，这种作用可能反过来触发细胞氧自由基损伤。虽然多种分子机制可能是造成胞质儿茶酚胺稳态扰动的原因，但本研究提供了关于α-突触核蛋白如何发挥其细胞毒性并选择性损伤儿茶酚胺能细胞的关键证据。
Dysregulation of dopamine homeostasis and elevation of the cytosolic level of the transmitter have been suggested to underlie the vulnerability of catecholaminergic neurons in Parkinson's disease. Because several known mutations in alpha-synuclein or overexpression of the wild-type(WT) protein causes familial forms of Parkinson's disease, we investigated possible links between alpha-synuclein pathogenesis and dopamine homeostasis. Chromaffin cells isolated from transgenic mice that overexpress A30P alpha-synuclein displayed significantly increased cytosolic catecholamine levels as measured by intracellular patch electrochemistry, whereas cells overexpressing the WT protein and those from knock-out animals were not different from controls. Likewise, catechol concentrations were higher in L-DOPA-treated PC12 cells overexpressing A30P or A53T compared with those expressing WT alpha-synuclein, although the ability of cells to maintain a low cytosolic dopamine level after L-DOPA challenge was markedly inhibited by either protein. We also found that incubation with low-micromolar concentrations of WT, A30P, or A53T alpha-synuclein inhibited ATP-dependent maintenance of pH gradients in isolated chromaffin vesicles and that the WT protein was significantly less potent in inducing the proton leakage. In summary, we demonstrate that overexpression of different types of alpha-synuclein disrupts vesicular pH and leads to a marked increase in the levels of cytosolic catechol species, an effect that may in turn trigger cellular oxyradical damage. Although multiple molecular mechanisms may be responsible for the perturbation of cytosolic catecholamine homeostasis, this study provides critical evidence about how alpha-synuclein might exert its cytotoxicity and selectively damage catecholaminergic cells.