A chloride conductance in VGLUT1 underlies maximal glutamate loading into synaptic vesicles
A chloride conductance in VGLUT1 underlies maximal glutamate loading into synaptic vesicles
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DOI：
10.1038/nn.2248
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发表时间：
2009-02-01
影响因子：
25
通讯作者：
Takamori, Shigeo
中科院分区：
文献类型：
--
作者：
Schenck, Stephan;Wojcik, Sonja M.;Takamori, Shigeo
突触囊泡对谷氨酸的摄取是由囊泡谷氨酸转运蛋白（VGLUT）介导的。虽然谷氨酸摄取已被证明是严重依赖于Cl-，这种离子的运输过程的精确贡献是不清楚的。我们发现，VGLUT 1，而不是ClC-3如前所述，代表了突触囊泡中的主要Cl-渗透途径。使用重建的VGLUT 1，我们发现，双相依赖的谷氨酸转运囊外Cl-是通过VGLUT 1本身的这种阴离子的渗透的结果。此外，我们观察到，高管腔Cl-浓度显着增强加载的谷氨酸膜电位驱动的吸收促进，并发现了迄今未被识别的运输模式VGLUT 1。由于内吞突触囊泡中存在跨越突触囊泡膜的陡峭Cl-梯度，因此我们的结果意味着转运速度和最终谷氨酸含量受到细胞外Cl-浓度的高度影响（如果不是确定的话）。
Uptake of glutamate into synaptic vesicles is mediated by vesicular glutamate transporters (VGLUTs). Although glutamate uptake has been shown to depend critically on Cl-, the precise contribution of this ion to the transport process is unclear. We found that VGLUT1, and not ClC-3 as proposed previously, represents the major Cl- permeation pathway in synaptic vesicles. Using reconstituted VGLUT1, we found that the biphasic dependence of glutamate transport on extravesicular Cl- is a result of the permeation of this anion through VGLUT1 itself. Moreover, we observed that high luminal Cl- concentrations markedly enhanced loading of glutamate by facilitation of membrane potential-driven uptake and discovered a hitherto unrecognized transport mode of VGLUT1. Because a steep Cl- gradient across the synaptic vesicle membrane exists in endocytosed synaptic vesicles, our results imply that the transport velocity and the final glutamate content are highly influenced, if not determined, by the extracellular Cl- concentration.