Kitayama S, Mitsuhata C, Davis S, Wang J B, Sato T, Morita K, Uhl G R, Dohi T
Department of Pharmacology, Hiroshima University School of Dentistry, Kasumi 1-2-3, Minami-ku, Hiroshima 734, Japan.
Biochim Biophys Acta. 1998 Sep 16;1404(3):305-13. doi: 10.1016/s0167-4889(98)00071-8.
The Parkinsonism-inducing neurotoxin 1-methyl-4-phenylpyridinium (MPP+) causes specific cell death in dopaminergic neurons after accumulation by the dopamine transporter (DAT). COS cells, a non-neuronal cell line insensitive to high doses of MPP+, becomes sensitive to MPP+ when transfected with the rat DAT cDNA. We analyzed the bi-directional transport of MPP+ and its toxicity in several cell lines expressing wild or mutant DATs. Cell death in COS cells expressing wild DAT by exposure to MPP+ was concentration-dependent and cocaine-reversible. Increased wild DAT expression caused higher sensitivities to the toxin in HeLa cells. Although several mutant DATs demonstrated greater transport activity than the wild-type, they displayed similar or lower sensitivity to MPP+ toxicity. Reverse transport of preloaded [3H]MPP+ through DAT was facilitated in COS cells expressing certain mutant DATs, which consistently displayed less sensitivity to MPP+ toxicity. These results suggest that re-distribution of MPP+ due to influx/efflux turnover through the transporter is a key factor in MPP+ toxicity.
帕金森氏症诱导神经毒素1-甲基-4-苯基吡啶鎓（MPP+）通过多巴胺转运体（DAT）积累后，会导致多巴胺能神经元发生特异性细胞死亡。COS细胞是一种对高剂量MPP+不敏感的非神经元细胞系，当用大鼠DAT cDNA转染时，它会对MPP+变得敏感。我们分析了MPP+在几种表达野生型或突变型DAT的细胞系中的双向转运及其毒性。通过暴露于MPP+，表达野生DAT的COS细胞中的细胞死亡呈浓度依赖性且可被可卡因逆转。野生DAT表达的增加导致HeLa细胞对该毒素的敏感性更高。尽管几种突变型DAT表现出比野生型更高的转运活性，但它们对MPP+毒性的敏感性相似或更低。在表达某些突变型DAT的COS细胞中，预加载的[3H]MPP+通过DAT的逆向转运得到促进，这些细胞对MPP+毒性始终表现出较低的敏感性。这些结果表明，由于通过转运体的流入/流出周转导致的MPP+重新分布是MPP+毒性的关键因素。
