Abstract
Chronic complex I inhibition caused by rotenone induces features of Parkinson's disease in rats, including selective nigrostriatal dopaminergic degeneration and Lewy bodies with α-synuclein-positive inclusions. To determine the mechanisms underlying rotenone-induced neuronal death, we used an in vitro model of human dopaminergic SH-SY5Y cells. In rotenone-induced cell death, rotenone induced Bad dephosphorylation without changing the amount of Bad proteins. Rotenone also increased the amount of α-synuclein in cells showing morphological changes in response to rotenone. Because Bad and α-synuclein are known to bind to 14-3-3 proteins, we examined the effects of rotenone on these complexes. Whereas a decreased Bad amount bound to 14-3-3 proteins, rotenone increased α-synuclein binding to these proteins. Beccause dephosphorylation by calcineurin activates Bad, we examined the possible involvement of Bad activation in rotenone-induced apoptosis by using the calcineurin inhibitor tacrolimus (FK506). Tacrolimus suppressed two rotenone-induced actions: Bad dephosphorylation and apoptosis. Furthermore, the inhibition of caspase-9, which functions downstream from Bad, completely suppressed rotenone-induced apoptosis. Our findings demonstrate that Bad activation plays a role in rotenone-induced apoptosis of SH-SY5Y cells.
Footnotes
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This work was supported in part by a grant-in-aid for scientific research from the Ministry of Education, Science and Culture of Japan.
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doi:10.1124/jpet.104.071381.
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ABBREVIATIONS: Z-VAD-FMK, N-benzyloxycarbonyl-Val-Ala-Asp(O-Me) fluoromethyl ketone; Z-LEHD-FMK, Z-Leu-Glu(O-ME)-His-Asp(O-Me) fluoromethyl ketone; PBS, phosphate-buffered saline.
- Received May 26, 2004.
- Accepted July 27, 2004.
- The American Society for Pharmacology and Experimental Therapeutics
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