Activation of phosphoinositide-3 kinase/Akt pathway by FeSO4 in rat cerebral cortex synaptic endings.
The aim of this work was to study the involvement of the phosphoinositide-3-kinase (PI3K)/Akt pathway in synaptic endings incubated under oxidative stress conditions. Synaptosomes purified from rat cerebral cortex were exposed to FeSO4 (50 microM) for different periods of time. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction and lactate dehydrogenate (LDH) leakage were significantly affected after 5 min of incubation in the presence of FeSO4, with respect to control conditions. In whole synaptosomes incubated in the presence of [gamma-(32)P]ATP, phosphoinositide (PPI) labeling was increased after 5 min of Fe2+ exposure. This effect was prevented by the specific PI3K inhibitor LY294002. Anti-p85 immunoprecipitates (IPs) obtained from synaptosomes preincubated with Fe2+ (5 min) showed a PI3K activity two-fold higher than the activity recovered under control conditions. Additionally, Akt activation was temporally coincident with PI3K activation. LY294002 was not able to prevent the LDH leakage and diminution of MTT reduction induced by Fe2+. Our results demonstrate that free iron provokes the early activation of PI3K/Akt pathway, but this activation is not sufficient for protecting synaptic endings from oxidative damage.
Uranga
Romina M
RM
Instituto de Investigaciones Bioquímicas de Bahía Blanca, Universidad Nacional del Sur and Consejo Nacional de Investigaciones Científicas y Técnicas, Bahía Blanca, Argentina.
Mateos
Melina V
MV
Giusto
Norma M
NM
Salvador
Gabriela A
GA
D000818:Animals; D002540:Cerebral Cortex / Q000648:ultrastructure*; D002867:Chromones / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005296:Ferrous Compounds / Q000494:pharmacology*; D018698:Glutamic Acid / Q000502:physiology; D047468:Immunoprecipitation; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000187:drug effects*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D013778:Tetrazolium Salts; D013844:Thiazoles; D013997:Time Factors
D002867:Chromones; D004791:Enzyme Inhibitors; D005296:Ferrous Compounds; D009025:Morpholines; D013778:Tetrazolium Salts; D013844:Thiazoles; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C020748:ferrous sulfate; D018698:Glutamic Acid; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; C022616:thiazolyl blue