Amphetamine-induced loss of human dopamine transporter activity: An internalization-dependent and cocaine-sensitive mechanism
Amphetamine-induced loss of human dopamine transporter activity: An internalization-dependent and cocaine-sensitive mechanism
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DOI：
10.1073/pnas.110035297
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发表时间：
2000-06-06
影响因子：
11.1
通讯作者：
Galli, A
中科院分区：
文献类型：
--
作者：
Saunders, C;Ferrer, JV;Galli, A
多巴胺转运体（DAT）是安非他明（AMPH）和可卡因的靶标。这些精神兴奋剂减弱DAT清除效率，从而增加突触多巴胺（DA）水平。再摄取速率是由细胞表面功能性转运蛋白的数量以及它们的周转率决定的。在这里，我们提出的证据表明，数据底物，包括AMPH和DA，导致人类数据的内在化，从而降低了运输能力。急性AMPH治疗降低了[H-3]DA的最大摄取率，降低了AMPH诱导的电流，并显著地将表位标记的DAT的免疫荧光从质膜重新分布到人胚胎肾293细胞的胞质溶胶中。相反，当与AMPH一起给药时，DAT抑制剂，如可卡因、马辛多尔和诺非芬，会阻止[H-3]DA摄取的减少和DAT免疫荧光向细胞质的重新分配。[H-3]DA摄取的减少和amph诱导的DAT内化也被动力蛋白I显性阴性突变体（K44A）的共表达所抑制，这表明内吞作用可能通过网状蛋白介导的途径调节运输能力。在这种调节机制下，急性应用AMPH不仅会通过直接竞争摄取来减少DA的摄取，还会通过减少可用的细胞表面DAT来减少DA的摄取。此外，amph诱导的内化可能减少可用于DA外排的DAT量，从而调节细胞外DA升高的细胞毒性作用。
The dopamine transporter (DAT) is a target of amphetamine (AMPH) and cocaine. These psychostimulants attenuate DAT clearance efficiency, thereby increasing synaptic dopamine (DA) levels. Re-uptake rate is determined by the number of functional transporters at the cell surface as well as by their turnover rate. Here, we present evidence that DAT substrates, including AMPH and DA, cause internalization of human DAT, thereby reducing transport capacity. Acute treatment with AMPH reduced the maximal rate of [H-3]DA uptake, decreased AMPH-induced currents, and significantly redistributed the immunofluorescence of an epitope-tagged DAT from the plasma membrane to the cytosol in human embryonic: kidney 293 cells. Conversely, DAT inhibitors, such as cocaine, mazindol, and nomifensine, when administered with AMPH, blocked the reduction in [H-3]DA uptake and the redistribution of DAT immunofluorescence to the cytosol. The reductions of [H-3]DA uptake and AMPH-induced DAT internalization also were inhibited by coexpression of a dominant negative mutant of dynamin I (K44A), indicating that endocytosis modulates transport capacity, likely through a clathrin-mediated pathway. With this mechanism of regulation, acute application of AMPH would reduce DA uptake not only by direct competition for uptake, but also by reducing the available cell-surface DAT. Moreover, AMPH-induced internalization might diminish the amount of DAT available for DA efflux, thereby modulating the cytotoxic effects of elevated extracellular DA.