[show abstract][hide abstract] ABSTRACT: Growth Arrest Specific 1 (GAS1) is a protein expressed when cells are arrested and during development. When ectopically expressed, GAS1 induces cell arrest and apoptosis of different cell lines, and we have previously demonstrated that the apoptotic process set off by GAS1 is caused by its capacity inhibiting the GDNF-mediated intracellular survival signaling. In the present work, we have dissected the molecular pathway leading to cell death. We employed the SH-SY5Y human neuroblastoma cell line that expresses GAS1 when deprived of serum. We observed, as we have previously described, that the presence of GAS1 reduces RET phosphorylation and inhibits the activation of AKT. We have now determined that the presence of GAS1 also triggers the dephosphorylation of BAD, which, in turn, provokes the release of Cytochrome-c from the mitochondria to the cytosol activating caspase-9, prompting the activity of caspase-3 and resulting in apoptosis of the cells. The apoptotic process is intrinsic, because there is no activation of caspase-8, thus this is consistent with apoptosis induced by the lack of trophic support. Interestingly, in cells where GAS1 has been silenced there is a significant delay in the onset of apoptosis.
[show abstract][hide abstract] ABSTRACT: Nitric oxide (NO) is an essential messenger molecule in brain, where it is produced in neurons mostly by the activity of the neuronal isoform of nitric oxide synthase (nNOS). To understand the participation of the different isoforms of NOS in physiological functioning and in pathological processes, mice with null mutations for each of the NOS isoforms have been generated. In the present paper, we report that there is a selective protection from oxidative damage in the brain of mice with a targeted disruption of the nNOS gene. The cerebellum of these mice shows reduced levels of lipid peroxidation (LP) at the different ages tested, compared with wild-type mice, and also a reduction in the formation of reactive oxygen species (ROS). We observed a decrease of LP in cortex, and no effect on either LP or ROS formation was observed in striatum of knockout mice compared with wild type. We also report increased spontaneous motor activity of knockout mice. The expression and activity of nNOS are crucial to maintain redox status in brain, and we consider that the alteration in oxidative damage may help us to explain the phenotypical characteristics of nNOS knockout mice and their differential susceptibility to brain insults.
Journal of Neuroscience Research 06/2007; 85(7):1391-402. · 2.97 Impact Factor