Inhibition of PTEN by peroxynitrite activates the phosphoinositide-3-kinase/Akt neuroprotective signaling pathway.
Peroxynitrite is usually considered as a neurotoxic nitric oxide-derivative. However, an increasing body of evidence suggests that, at low concentrations, peroxynitrite affords transient cytoprotection, both in vitro and in vivo. Here, we addressed the signaling mechanism responsible for this effect, and found that rat cortical neurons in primary culture acutely exposed to peroxynitrite (0.1 mmol/L) rapidly elicited Akt-Ser(473) phosphorylation. Inhibition of phosphoinositide-3-kinase (PI3K)/Akt pathway with wortmannin or Akt small hairpin RNA (shRNA) abolished the ability of peroxynitrite to prevent etoposide-induced apoptotic death. Endogenous peroxynitrite formation by short-term incubation of neurons with glutamate stimulated Akt-Ser(473) phosphorylation, whereas Akt shRNA enhanced the vulnerability of neurons against glutamate. We further show that Akt-Ser(473) phosphorylation was consequence of the oxidizing, but not the nitrating properties of peroxynitrite. Peroxynitrite failed to nitrate or phosphorylate neurotrophin tyrosine kinase receptors (Trks), and it did not modify the ability of brain-derived neurotrophic factor (BDNF), to phosphorylate its cognate receptor, TrkB; however, peroxynitrite enhanced BDNF-mediated Akt-Ser(473) phosphorylation. Finally, we found that peroxynitrite-stimulated Akt-Ser(473) phosphorylation was associated with an increased proportion of oxidized phosphoinositide phosphatase, PTEN, in neurons. Moreover, peroxynitrite prevented the increase of apoptotic neuronal death caused by over-expression of PTEN. Thus, peroxynitrite exerts neuroprotection by inhibiting PTEN, hence activating the anti-apoptotic PI3K/Akt pathway in primary neurons.
Delgado-Esteban
Maria
M
Departamento de Bioquímica y Biología Molecular, Instituto de Neurociencias de Castilla y León, Universidad de Salamanca, Salamanca, Spain.
Martin-Zanca
Dionisio
D
Andres-Martin
Laura
L
Almeida
Angeles
A
Bolaños
Juan P
JP
D000972:Antineoplastic Agents, Phytogenic / Q000037:antagonists & inhibitors / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000187:drug effects; D005047:Etoposide / Q000037:antagonists & inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D006801:Humans; D047468:Immunoprecipitation; D009249:NADP / Q000378:metabolism; D009410:Nerve Degeneration / Q000517:prevention & control; D018696:Neuroprotective Agents / Q000494:pharmacology*; D051058:Oncogene Protein v-akt / Q000378:metabolism*; D010084:Oxidation-Reduction; D051059:PTEN Phosphohydrolase / Q000037:antagonists & inhibitors*; D030421:Peroxynitrous Acid / Q000138:chemical synthesis / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation; D010957:Plasmids / Q000235:genetics; D012313:RNA / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects*; D014162:Transfection
D000972:Antineoplastic Agents, Phytogenic; D018696:Neuroprotective Agents; D030421:Peroxynitrous Acid; D009249:NADP; D012313:RNA; D005047:Etoposide; D019869:Phosphatidylinositol 3-Kinases; D051058:Oncogene Protein v-akt; D051059:PTEN Phosphohydrolase