Oxidative Stress triggers phosphoinositide 3-kinase/Akt, c-Src and Erk signaling in rat cerebral cortex synaptic endings

URANGA, ROMINA; GIUSTO NORMA; SALVADOR GABRIELA AUTOR CORRESP.

Washington

Congreso; 38th Annual Meeting of the Society for Neuroscience (SFN); 2009

Society for Neuroscience

Oxidative stress triggers phosphoinositide 3-kinase/Akt, c-Src and Erk signaling in rat cerebral cortex synaptic endings¡±. Uranga, R.M. 1, 2, 3, Giusto, N.M. 1, 2, 3, Salvador, G.A. 1, 2, 3 1 Instituto de Investigaciones Bioqu¨ªmicas de Bah¨ªa Blanca, Bah¨ªa Blanca, Argentina. 2 Universidad Nacional del Sur, Bah¨ªa Blanca, Argentina. 3 Consejo Nacional de Investigaciones Cient¨ªficas y T¨¦cnicas, Bah¨ªa Blanca, Argentina. The exposure to metal ions such as Fe2+ is considered a potent oxidative damage inducer. This type of oxidative injury is comparable to that of ¦Â-amyloid peptide (¦ÂA) on the brain of Alzheimer¡¯s disease patients. In our experimental model, synaptosomes obtained from adult Wistar rats were exposed to FeSO4 (50 ¦ÌM) for different periods of time (5, 30 and 60 min) and viability parameters and the state of different signal transduction pathways were measured. Mitochondrial function, glutamate uptake and plasma membrane integrity were affected by the presence of Fe2+, with respect to control conditions after 5, 30 and 60 min of incubation. Synaptosomes and anti-p85 inmunoprecipitates (IP) incubated in the presence of [¦Ã-32P]ATP showed an increase in PI3K activity after 5 min of Fe2+-exposure. The increase in Akt phosphorylation in serine 473 and threonine 308 was temporally coincident with PI3K activation. Experiments carried out in the presence of sodium orthovanadate or herbimycin A indicated the involvement of tyrosine phosphorylation in PI3K activation induced by Fe2+. IPs of c-Src demonstrated a strong association between Akt, p-Akt and this tyrosine kinase induced by oxidative stress. The downstream Akt effector, GSK3¦Â, was also phosphorylated after 5 and 30 min of iron exposure and this phosphorylation was inhibited by LY294002. Additionally, Erk activation was observed after 5 and 60 min of insult exposure, but only the latter activation was PI3K-dependent. Our results demonstrate that oxidative stress triggers the activation of different synaptic signaling pathways such as PI3K/Akt, c-Src, GSK3¦Â and Erk.