MPP+ toxicity and plasma membrane dopamine transporter: study using cell lines expressing the wild-type and mutant rat dopamine transporters.
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.
Kitayama
S
S
Department of Pharmacology, Hiroshima University School of Dentistry, Kasumi 1-2-3, Minami-ku, Hiroshima 734, Japan. shigeok@ipc.hiroshima-u.ac.jp
Mitsuhata
C
C
Davis
S
S
Wang
J B
JB
Sato
T
T
Morita
K
K
Uhl
G R
GR
Dohi
T
T
D015655:1-Methyl-4-phenylpyridinium / Q000037:antagonists & inhibitors / Q000633:toxicity*; D000818:Animals; D001692:Biological Transport; D019556:COS Cells; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D002470:Cell Survival; D003042:Cocaine / Q000494:pharmacology; D015259:Dopamine Agents / Q000633:toxicity*; D050483:Dopamine Plasma Membrane Transport Proteins; D004305:Dose-Response Relationship, Drug; D006367:HeLa Cells; D006540:Herbicides / Q000633:toxicity*; D006801:Humans; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D051381:Rats; D013778:Tetrazolium Salts; D014162:Transfection
C110656:2-(4-iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium; D002352:Carrier Proteins; D015259:Dopamine Agents; D050483:Dopamine Plasma Membrane Transport Proteins; D006540:Herbicides; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; C493214:SLC6A3 protein, human; C493216:Slc6a3 protein, rat; D013778:Tetrazolium Salts; D003042:Cocaine; D015655:1-Methyl-4-phenylpyridinium