Acute increase of α-synuclein inhibits synaptic vesicle recycling evoked during intense stimulation.
Acute increase of α-synuclein inhibits synaptic vesicle recycling evoked during intense stimulation.
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DOI：
10.1091/mbc.e14-02-0708
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发表时间：
2014-12-01
影响因子：
3.3
通讯作者：
Morgan JR
中科院分区：
文献类型：
--
作者：
Busch DJ;Oliphint PA;Walsh RB;Banks SM;Woods WS;George JM;Morgan JR
这是第一个研究表明α-突触核蛋白对突触囊泡运输的直接影响，并阐明了潜在的结构机制。急剧增加的α-突触核蛋白严重抑制突触囊泡从质膜的再循环。内吞缺陷需要α-突触核蛋白的N-末端α-螺旋结构域正确折叠。帕金森病与α-突触核蛋白基因的增殖和蛋白质的异常积累有关。在动物模型中，α-突触核蛋白过度表达广泛损害突触囊泡运输。然而，过量的α-突触核蛋白影响囊泡运输途径的确切步骤和潜在的分子机制仍然未知。因此，我们在脊椎动物突触中急剧增加突触核蛋白水平，并对突触前膜的影响进行了详细的超微结构分析。在刺激的突触（20赫兹），过量的突触核蛋白引起突触囊泡的损失和质膜的扩张，表明损害囊泡回收。突触核蛋白的N-末端结构域（NTD）折叠成α-螺旋，足以重现这些效应。相反，N-末端α-螺旋被破坏的α-突触核蛋白突变体（T6 K和A30 P）在相同条件下几乎没有影响。另一种具有正确折叠的NTD的α-突触核蛋白突变体（A53 T）进一步支持该模型，其表型模仿了野生型中观察到的突触囊泡再循环缺陷。有趣的是，当刺激频率降低（5 Hz）时，未观察到囊泡再循环缺陷。因此，过量的α-突触核蛋白通过需要适当折叠的N-末端α-螺旋的机制损害在强烈刺激期间诱发的突触囊泡再循环。
This is the first study to show the direct effects of α-synuclein on synaptic vesicle trafficking and to elucidate the underlying structural mechanisms. Acutely increasing α-synuclein severely inhibits synaptic vesicle recycling from the plasma membrane. The endocytic defects require a properly folded N-terminal α-helical domain of α-synuclein. Parkinson's disease is associated with multiplication of the α-synuclein gene and abnormal accumulation of the protein. In animal models, α-synuclein overexpression broadly impairs synaptic vesicle trafficking. However, the exact steps of the vesicle trafficking pathway affected by excess α-synuclein and the underlying molecular mechanisms remain unknown. Therefore we acutely increased synuclein levels at a vertebrate synapse and performed a detailed ultrastructural analysis of the effects on presynaptic membranes. At stimulated synapses (20 Hz), excess synuclein caused a loss of synaptic vesicles and an expansion of the plasma membrane, indicating an impairment of vesicle recycling. The N-terminal domain (NTD) of synuclein, which folds into an α-helix, was sufficient to reproduce these effects. In contrast, α-synuclein mutants with a disrupted N-terminal α-helix (T6K and A30P) had little effect under identical conditions. Further supporting this model, another α-synuclein mutant (A53T) with a properly folded NTD phenocopied the synaptic vesicle recycling defects observed with wild type. Interestingly, the vesicle recycling defects were not observed when the stimulation frequency was reduced (5 Hz). Thus excess α-synuclein impairs synaptic vesicle recycling evoked during intense stimulation via a mechanism that requires a properly folded N-terminal α-helix.