Oxidative stress and endoplasmic reticulum (ER) stress have been associated with Alzheimer's disease (AD) progression. In this study we analyzed whether oxidative stress involving changes in Nrf2 and ER stress may constitute early events in AD pathogenesis by using human peripheral blood cells and an AD transgenic mouse model at different disease stages. Increased oxidative stress and increased phosphorylated Nrf2 (p(Ser40)Nrf2) were observed in human peripheral blood mononuclear cells (PBMCs) isolated from individuals with mild cognitive impairment (MCI). Moreover, we observed impaired ER Ca2+ homeostasis and increased ER stress markers in PBMCs from MCI individuals and mild AD patients. Evidence of early oxidative stress defense mechanisms in AD was substantiated by increased p(Ser40)Nrf2 in 3month-old 3xTg-AD male mice PBMCs, and also with increased nuclear Nrf2 levels in brain cortex. However, SOD1 protein levels were decreased in human MCI PBMCs and in 3xTg-AD mice brain cortex; the latter further correlated with reduced SOD1 mRNA levels. Increased ER stress was also detected in the brain cortex of young female and old male 3xTg-AD mice. We demonstrate oxidative stress and early Nrf2 activation in AD human and mouse models, which fails to regulate some of its targets, leading to repressed expression of antioxidant defenses (e.g., SOD-1), and extending to ER stress. Results suggest markers of prodromal AD linked to oxidative stress associated with Nrf2 activation and ER stress that may be followed in human peripheral blood mononuclear cells.

Sirtuin 1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD)-dependent lysine deacetylase that regulates longevity and enhances mitochondrial metabolism. Both activation and inhibition of SIRT1 were previously shown to ameliorate neuropathological mechanisms in Huntington's disease (HD), a neurodegenerative disease that selectively affects the striatum and cortex and is commonly linked to mitochondrial dysfunction. Thus, in this study, we tested the influence of resveratrol (RESV, a SIRT1 activator) versus nicotinamide (NAM, a SIRT1 inhibitor) in counteracting mitochondrial dysfunction in HD models, namely striatal and cortical neurons isolated from YAC128 transgenic mice embryos, HD human lymphoblasts, and an in vivo HD model. HD cell models displayed a deregulation in mitochondrial membrane potential and respiration, implicating a decline in mitochondrial function. Further studies revealed decreased PGC-1α and TFAM protein levels, linked to mitochondrial DNA loss in HD lymphoblasts. Remarkably, RESV completely restored these parameters, while NAM increased NAD levels, providing a positive add on mitochondrial function in in vitro HD models. In general, RESV decreased while NAM increased H3 acetylation at lysine 9. In agreement with in vitro data, continuous RESV treatment for 28 days significantly improved motor coordination and learning and enhanced expression of mitochondrial-encoded electron transport chain genes in YAC128 mice. In contrast, high concentrations of NAM blocked mitochondrial-related transcription, worsening motor phenotype. Overall, data indicate that activation of deacetylase activity by RESV improved gene transcription associated to mitochondrial function in HD, which may partially control HD-related motor disturbances.

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Alzheimer's disease (AD) is the major cause of dementia in the world. Abnormal extracellular accumulation of amyloid-β (Aβ) peptide and tau hyperphosphorylation, forming neurofibrillary tangles in the brain, are hallmarks of the disease. Oxidative stress, neuroinflammation, and mitochondrial and synaptic dysfunction are also observed in AD and often correlated to intracellular Aβ. This peptide results from the cleavage of the amyloid-β protein precursor by β- and γ-secretases and tends to be secreted after its production. However, secreted Aβ can be internalized by the interaction with membrane receptors, namely N-methyl-D-aspartate receptors, advanced glycation end products receptors, and/or alpha 7 nicotinic acetylcholine receptors. Inside the cell, Aβ interacts with several organelles, including mitochondria and nucleus, and there is growing evidence pointing to a possible role of Aβ in the regulation of gene transcription. Accordingly, transcriptional deregulation was observed in several AD models and human samples from AD patients through modified expression, phosphorylation levels, function, and subcellular localization of some transcription factors, resulting in the suppression of neuroprotective transcription both in the nucleus and the mitochondria. In this review we focus on key transcription regulators related with mitochondrial biogenesis and antioxidant defenses that seem to be altered in AD models and also on the role of intranuclear Aβ in the pathogenesis of the disease.

Autism spectrum disorder (ASD) is characterized by dysfunction in social interactions, stereotypical behaviours and high co-morbidity with intellectual disability. A variety of syndromic and non-syndromic neurodevelopmental disorders have been connected to alterations in metabotropic glutamate receptor (mGluR) signalling. These receptors contribute to synaptic plasticity, spine maturation and circuit development. Here, we investigate the physiological role of Gprasp2 , a gene linked to neurodevelopmental disabilities and involved in the postendocytic sorting of G-protein-coupled receptors. We show that Gprasp2 deletion leads to ASD-like behaviour in mice and alterations in synaptic communication. Manipulating the levels of Gprasp2 bidirectionally modulates the surface availability of mGluR 5 and produces alterations in dendritic complexity, spine density and synaptic maturation. Loss of Gprasp2 leads to enhanced hippocampal long-term depression, consistent with facilitated mGluR-dependent activation. These findings demonstrate a role for Gprasp2 in glutamatergic synapses and suggest a possible mechanism by which this gene is linked to neurodevelopmental diseases.