Alzheimer's disease amyloid beta-protein forms Zn2+-sensitive, cation-selective channels across excised membrane patches from hypothalamic neurons
Alzheimer's disease amyloid beta-protein forms Zn2+-sensitive, cation-selective channels across excised membrane patches from hypothalamic neurons
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DOI：
10.1016/s0006-3495(97)78048-2
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发表时间：
1997-07-01
影响因子：
3.4
通讯作者：
Rojas, E
中科院分区：
文献类型：
--
作者：
Kawahara, M;Arispe, N;Rojas, E
我们以前已经证明，40个残基的肽称为淀粉样β蛋白（A β P[1-40]）在溶液中形成阳离子选择性通道跨越人工磷脂双层膜。为了确定A β P[1-40]是否也形成穿过天然膜的通道，我们使用了来自下丘脑促性腺激素释放激素GnRH神经元的细胞系的电沉默切除膜贴片。我们发现，将切除膜贴片的内侧或外侧暴露于A β P[1-40]导致阳离子选择性通道的自发形成。在外部和内部盐水中以Cs+作为主要阳离子，发现A β P[1-40]通道电流的幅度遵循Cs+梯度，并在宽范围（50-500 pS）内表现出自发电导变化。我们还发现，游离锌（Zn 2+），据报道，在溶液中结合淀粉样β蛋白，可以阻止Cs+通过A β P[1-40]通道的流动。由于Zn 2+螯合剂邻菲咯啉可以逆转这种阻断，我们得出结论，潜在的机制涉及过渡元素Zn 2+和A β P[1-40]通道孔中的位点之间的直接相互作用。A β P[1-40]通道的这些特性与在人工双层系统中观察到的特性非常相似。我们还通过免疫细胞化学共聚焦显微镜显示，淀粉样β蛋白分子形成与相当一部分GnRH神经元的质膜密切相关的沉积物。总之，这些结果表明，淀粉样β蛋白和神经元膜之间的相互作用也发生在体内，贷款进一步支持的想法，A β P[1-40]通道的形成可能是淀粉样β蛋白神经毒性的机制。
We have previously shown that the 40-residue peptide termed amyloid beta-protein (A beta P[1-40]) in solution forms cation-selective channels across artificial phospholipid bilayer membranes. To determine whether A beta P[1-40] also forms channels across natural membranes, we used electrically silent excised membrane patches from a cell line derived from hypothalamic gonadotrophin-releasing hormone GnRH neurons, We found that exposing either the internal or the external side of excised membrane patches to A beta P[1-40] leads to the spontaneous formation of cation-selective channels. With Cs+ as the main cation in both the external as well as the internal saline, the amplitude of the A beta P[1-40] channel currents was found to follow the Cs+ gradient and to exhibit spontaneous conductance changes over a wide range (50-500 pS). We also found that free zinc (Zn2+), reported to bind to amyloid beta-protein in solution, can block the flow of Cs+ through the A beta P[1-40] channel. Because the Zn2+ chelator o-phenanthroline can reverse this blockade, we conclude that the underlying mechanism involves a direct interaction between the transition element Zn2+ and sites in the A beta P[1-40] channel pore. These properties of the A beta P[1-40] channel are rather similar to those observed in the artificial bilayer system, We also show here, by immunocytochemical confocal microscopy, that amyloid beta-protein molecules form deposits closely associated with the plasma membrane of a substantial fraction of the GnRH neurons. Taken together, these results suggest that the interactions between amyloid beta-protein and neuronal membranes also occur in vivo, lending further support to the idea that A beta P[1-40] channel formation might be a mechanism of amyloid beta-protein neurotoxicity.