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Involvement of Bcl‐2 Family and Caspase‐3‐Like Protease in NO‐Mediated Neuronal Apoptosis
Author(s) -
Tamatani Michio,
Ogawa Satoshi,
Niitsu Youichirou,
Tohyama Masaya
Publication year - 1998
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 - 10.1046/j.1471-4159.1998.71041588.x
Subject(s) - apoptosis , programmed cell death , nitric oxide , nitric oxide synthase , caspase 3 , microbiology and biotechnology , caspase , astrocyte , hypoxia (environmental) , biology , sodium nitroprusside , downregulation and upregulation , chemistry , biochemistry , endocrinology , central nervous system , organic chemistry , oxygen , gene
To clarify mechanisms of neuronal death in the postischemic brain, we examined whether astrocytes exposed to hypoxia/reoxygenation exert a neurotoxic effect, using a coculture system. Neurons cocultured with astrocytes subjected to hypoxia/reoxygenation underwent apoptotic cell death, the effect enhanced by a combination of interleukin‐1β with hypoxia. The synergistic neurotoxic activity of hypoxia and interleukin‐1β was dependent on de novo expression of inducible nitric oxide synthase (iNOS) and on nitric oxide (NO) production in astrocytes. Further analysis to determine the neurotoxic mechanism revealed decreased Bcl‐2 and increased Bax expression together with caspase‐3 activation in cortical neurons cocultured with NO‐producing astrocytes. Inhibition of NO production in astrocytes by N G ‐monomethyl‐ l ‐arginine, an inhibitor of NOS, significantly inhibited neuronal death together with changes in Bcl‐2 and Bax protein levels and in caspase‐3‐like activity. Moreover, treatment of neurons with a bax antisense oligonucleotide inhibited the caspase‐3‐like activation and neuronal death induced by an NO donor, sodium nitroprusside. These data suggest that NO produced by astrocytes after hypoxic insult induces apoptotic death of neurons through mechanisms involving the caspase‐3 activation after down‐regulation of BCl‐2 and up‐regulation of Bax protein levels.