Activation of Akt kinase inhibits apoptosis and changes in Bcl-2 and Bax expression induced by nitric oxide in primary hippocampal neurons.
Emerging data indicate that growth factors such as insulin-like growth factor-1 (IGF-1) prevent neuronal death due to nitric oxide (NO) toxicity. On the other hand, growth factors can promote cell survival by acting on phosphatidylinositol 3-kinase (PI3-kinase) and its downstream target, serine-threonine kinase Akt, in various types of cells. Here, we examined the mechanism by which IGF-1 inhibits neuronal apoptosis induced by NO in primary hippocampal neurons. IGF-1 was capable of preventing apoptosis and caspase-3-like activation induced by a NO donor, sodium nitroprusside or 3-morpholin-osydnonimine. Incubation of neurons with a P13-kinase inhibitor, wortmannin or LY294002, blocked the effects of IGF-1 on NO-induced neurotoxicity and caspase-3-like activation. In addition, the P13-kinase inhibitors blocked the effect of IGF-1 on down-regulation in Bcl-2 and upregulation in Bax expression induced by NO. Adenovirus-mediated overexpression of the activated form of Akt significantly inhibited NO-induced cell death, caspase-3-like activation, and changes in Bcl-2 and Bax expression. Moreover, expression of the kinase-defective form of Akt almost completely blocked the effects of IGF-1. These findings suggest that activation of Akt is necessary and sufficient for the effect of IGF-1 and is capable of preventing NO-induced apoptosis by modulating the NO-induced changes in Bcl-2 and Bax expression.
Matsuzaki
H
H
Department of Anatomy and Neuroscience, Osaka University Medical School, Japan.
Tamatani
M
M
Mitsuda
N
N
Namikawa
K
K
Kiyama
H
H
Miyake
S
S
Tohyama
M
M
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D005822:Genetic Vectors; D006624:Hippocampus / Q000166:cytology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D009569:Nitric Oxide / Q000494:pharmacology*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009599:Nitroprusside / Q000494:pharmacology; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D051057:Proto-Oncogene Proteins c-akt; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics*; D051381:Rats; D017207:Rats, Sprague-Dawley; D051028:bcl-2-Associated X Protein
C494828:Bax protein, rat; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein; D009599:Nitroprusside; D009569:Nitric Oxide; D007334:Insulin-Like Growth Factor I; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; C505410:Casp3 protein, rat; D053148:Caspase 3; D020169:Caspases