Pharmacological disruption of calcium channel trafficking by the α2δ ligand gabapentin
Pharmacological disruption of calcium channel trafficking by the α2δ ligand gabapentin
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DOI：
10.1073/pnas.0708930105
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发表时间：
2008-03-04
影响因子：
11.1
通讯作者：
Dolphin, Annette C.
中科院分区：
文献类型：
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作者：
Hendrich, Jan;Van Minh, Alexandra Tran;Dolphin, Annette C.
加巴喷丁类药物家族的抗癫痫和抗癫痫药物的作用机制仍然知之甚少。加巴喷丁（GBP）与电压门控钙通道的α (2) δ -1和α (2) δ -2辅助亚基的外表面表位结合，但GBP对钙电流的急性抑制要么很小，要么不存在。我们提出了一个假设，即GBP通过影响转运，削弱了α (2) δ亚基增强电压门控Ca（2+）通道质膜密度的能力。我们的研究结果最终表明，GBP抑制钙电流，只有在长期应用时才会模拟α (2) δ的缺乏，而不是在外源表达系统和背根神经节神经元中。GBP主要作用于细胞内，需要摄取，因为长期应用GBP的作用被系统l中性氨基酸转运蛋白的抑制剂阻断，并通过转运蛋白的共表达增强。然而，它是由α (2) δ亚基介导的，被α (2) δ -1或α (2) δ -2的突变所阻止，这些突变会消除GBP的结合，而α (2) δ -3则没有观察到，它不结合GBP。此外，α (2) δ -2和Ca(v)2通道的运输被GBP和α (2) δ -2的突变破坏，这阻止了GBP的结合，我们发现GBP降低了α (2) δ -2和Ca(v)2.1亚基的细胞表面表达。我们的证据表明，GBP可能通过取代通常是α (2) δ亚基功能的正调节剂的内源性配体而长期起作用，从而损害其结合的α (2) δ亚基的运输功能。
The mechanism of action of the antiepileptic and antinociceptive drugs of the gabapentinoid family has remained poorly understood. Gabapentin (GBP) binds to an exofacial epitope of the alpha(2)delta-1 and alpha(2)delta-2 auxiliary subunits of voltage-gated calcium channels, but acute inhibition of calcium currents by GBP is either very minor or absent. We formulated the hypothesis that GBP impairs the ability of alpha(2)delta subunits to enhance voltage-gated Ca(2+)channel plasma membrane density by means of an effect on trafficking. Our results conclusively demonstrate that GBP inhibits calcium currents, mimicking a lack of alpha(2)delta only when applied chronically, but not acutely, both in heterologous expression systems and in dorsal root-ganglion neurons. GBP acts primarily at an intracellular location, requiring uptake, because the effect of chronically applied GBP is blocked by an inhibitor of the system-L neutral amino acid transporters and enhanced by coexpression of a transporter. However, it is mediated by alpha(2)delta subunits, being prevented by mutations in either alpha(2)delta-1 or alpha(2)delta-2 that abolish GBP binding, and is not observed for alpha(2)delta-3, which does not bind GBP. Furthermore, the trafficking of alpha(2)delta-2 and Ca(v)2 channels is disrupted both by GBP and by the mutation in alpha(2)delta-2, which prevents GBP binding, and we find that GBP reduces cell-surface expression of alpha(2)delta-2 and Ca(v)2.1 subunits. Our evidence indicates that GBP may act chronically by displacing an endogenous ligand that is normally a positive modulator of alpha(2)delta subunit function, thereby impairing the trafficking function of the alpha(2)delta subunits to which it binds.