L-type Ca(2+) channel-mediated Zn(2+) toxicity and modulation by ZnT-1 in PC12 cells.
In view of evidence that Zn(2+) neurotoxicity contributes to some forms of pathological neuronal death, we developed a model of Zn(2+) neurotoxicity in a cell line amenable to genetic manipulations. Exposure to 500 microM ZnCl(2) for 15 min under depolarizing conditions resulted in modest levels of PC12 cell death, that was reduced by the L-type Ca(2+) channel antagonist, nimodipine, and increased by the L-type Ca(2+) channel opener, S(-)-Bay K 8644. At lower insult levels (200 micrometer Zn(2+)+Bay K 8644), Zn(2+)-induced death appeared apoptotic under electron microscopy and was sensitive to the caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-CH(2)F (Z-VAD); at higher insult levels (1000 microM+Bay K 8644), cells underwent necrosis insensitive to Z-VAD. To test the hypothesis that the plasma membrane transporter, ZnT-1, modulates Zn(2+) neurotoxicity, we generated stable PC12 cell lines overexpressing wild type or dominant negative forms of rat ZnT-1 (rZnT-1). Clones T9 and T23 overexpressing wild type rZnT-1 exhibited enhanced Zn(2+) efflux and reduced vulnerability to Zn(2+)-induced death compared to the parental line, whereas clones D5 and D16 expressing dominant negative rZnT-1 exhibited the opposite characteristics.
Kim
A H
AH
Department of Neurology and Center for the Study of Nervous System Injury, Washington University School of Medicine, 660 S. Euclid Ave., 63110, St. Louis, MO, USA
Sheline
C T
CT
Tian
M
M
Higashi
T
T
McMahon
R J
RJ
Cousins
R J
RJ
Choi
D W
DW
D000818:Animals; D017209:Apoptosis; D002120:Calcium Channel Agonists / Q000494:pharmacology; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020746:Calcium Channels, L-Type / Q000378:metabolism*; D027682:Cation Transport Proteins; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005682:Gadolinium / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism*; D009336:Necrosis; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D016716:PC12 Cells; D019289:Pyruvic Acid / Q000494:pharmacology; D051381:Rats; D015032:Zinc / Q000633:toxicity*
D002120:Calcium Channel Agonists; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D027682:Cation Transport Proteins; D015853:Cysteine Proteinase Inhibitors; D008565:Membrane Proteins; D018696:Neuroprotective Agents; D009842:Oligopeptides; C103712:benzyloxycarbonyl-valyl-alanyl-aspartyl-fluoromethane; C092392:Slc30a1 protein, rat; D019289:Pyruvic Acid; D005682:Gadolinium; D015032:Zinc