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Neuromelanin selectively induces apoptosis in dopaminergic SH‐SY5Y cells by deglutathionylation in mitochondria: involvement of the protein and melanin component
Author(s) -
Naoi Makoto,
Maruyama Wakako,
Yi Hong,
Yamaoka Yuriko,
ShamotoNagai Masayo,
Akao Yukihiro,
Gerlach Manfred,
Tanaka Masashi,
Riederer Peter
Publication year - 2008
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2008.05329.x
Subject(s) - neuromelanin , apoptosis , sh sy5y , mitochondrion , cytochrome c , programmed cell death , microbiology and biotechnology , reactive oxygen species , biology , western blot , dopaminergic , dopamine , chemistry , biochemistry , cell culture , substantia nigra , endocrinology , neuroblastoma , genetics , gene
Parkinson’s disease (PD) is characterized by selective depletion of nigral dopamine (DA) neurons containing neuromelanin (NM), suggesting the involvement of NM in the pathogenesis. This study reports induction of apoptosis by NM in SH‐SY5Y cells, whereas protease‐K‐treated NM, synthesized DA‐ and cysteinyl dopamine melanin showed much less cytotoxicity. Cell death was mediated by mitochondria‐mediated apoptotic pathway, namely collapse of mitochondrial membrane potential, release of cytochrome c , and activation of caspase 3, but Bcl‐2 over‐expression did not suppress apoptosis. NM increased sulfhydryl content in mitochondria, and a major part of it was identified as GSH, whereas dopamine melanin significantly reduced sulfhydryl levels. Western blot analysis for protein‐bound GSH demonstrated that only NM reduced S ‐glutathionylated proteins in mitochondria and dissociated macromolecular structure of complex I. Reactive oxygen and nitrogen species were required for the deglutathionylation by NM, which antioxidants reduced significantly with prevention of apoptosis. These results suggest that NM may be related to cell death of DA neurons in PD and aging through regulation of mitochondrial redox state and S ‐glutathionylation, for which NM‐associated protein is absolutely required. The novel function of NM is discussed in relation to the pathogenesis of PD.