Self-association of β-amyloid (Aβ) into oligomers and fibrils is associated with Alzheimer's disease (AD), motivating the search for compounds that bind to and inhibit Aβ oligomerization and/or neurotoxicity. Peptides are an attractive class of such compounds, with potential advantages over small molecules in affinity and specificity. Self-complementation and peptide library screening are two strategies that have been employed in the search for peptides that bind to Aβ. Alternatively, one could design Aβ-binding peptides based on knowledge of complementary binding proteins. One candidate protein, transthyretin (TTR), binds Aβ, inhibits aggregation, and reduces its toxicity. Previously, strand G of TTR was identified as part of a specific Aβ binding domain, and G16, a 16-mer peptide with a sequence that spans strands G and H of TTR, was synthesized and tested. Although both TTR and G16 bound to Aβ, they differed significantly in their effect on Aβ aggregation, and G16 was less effective than TTR at protecting neurons from Aβ toxicity. G16 lacks the β-strand/loop/β-strand structure of TTR's Aβ binding domain. To enforce proper residue alignment, we transplanted the G16 sequence onto a β-hairpin template. Two peptides with 18 and 22 amino acids were synthesized using an orthogonally protected glutamic acid derivative, and an N-to-C cyclization reaction was carried out to further restrict conformational flexibility. The cyclized 22-mer (but not the noncyclized 22-mer nor the 18-mer) strongly suppressed Aβ aggregation into fibrils, and protected neurons against Aβ toxicity. The imposition of structural constraints generated a much-improved peptidomimetic of the Aβ binding epitope on TTR.

The presence of senile plaques is one of the major pathologic hallmarks of the brain with Alzheimer's disease (AD). The plaques predominantly contain insoluble amyloid β-peptide, a cleavage product of the larger amyloid precursor protein (APP). Two enzymes, named β and γ secretase, generate the neurotoxic amyloid-β peptide from APP. Mature APP is also turned over endogenously by autophagy, more specifically by the endosomal-lysosomal pathway. A defective lysosomal system is known to be pathogenic in AD. Modulation of NF-E2 related factor 2 (Nrf2) has been shown in several neurodegenerative disorders, and Nrf2 has become a potential therapeutic target for various neurodegenerative disorders, including AD, Parkinson's disease, and amyotrophic lateral sclerosis. In the current study, we explored the effect of genetic ablation of Nrf2 on APP/Aβ processing and/or aggregation as well as changes in autophagic dysfunction in APP/PS1 mice. There was a significant increase in inflammatory response in APP/PS1 mice lacking Nrf2. This was accompanied by increased intracellular levels of APP, Aβ (1–42), and Aβ (1–40), without a change total full-length APP. There was a shift of APP and Aβ into the insoluble fraction, as well as increased poly-ubiquitin conjugated proteins in mice lacking Nrf2. APP/PS1-mediated autophagic dysfunction is also enhanced in Nrf2-deficient mice. Finally, neurons in the APP/PS1/Nrf2−/− mice had increased accumulation of multivesicular bodies, endosomes, and lysosomes. These outcomes provide a better understanding of the role of Nrf2 in modulating autophagy in an AD mouse model and may help design better Nrf2 targeted therapeutics that could be efficacious in the treatment of AD.

Self-association of β-amyloid (Aβ) into soluble oligomers and fibrillar aggregates is associated with Alzheimer's disease pathology, motivating the search for compounds that selectively bind to and inhibit Aβ oligomerization and/or neurotoxicity. Numerous small-molecule inhibitors of Aβ aggregation or toxicity have been reported in the literature. However, because of their greater size and complexity, peptides and peptidomimetics may afford improved specificity and affinity as Aβ aggregation modulators compared to small molecules. Two divergent strategies have been employed in the search for peptides that bind Aβ: (i) using recognition domains corresponding to sequences in Aβ itself (such as KLVFF) and (ii) screening random peptide-based libraries. In this study, we propose a third strategy, specifically, designing peptides that mimic binding domains of Aβ-binding proteins. Transthyretin, a plasma transport protein that is also relatively abundant in cerebrospinal fluid, has been shown to bind to Aβ, inhibit aggregation, and reduce its toxicity. Previously, we identified strand G of transthyretin as a specific Aβ binding domain. In this work we further explore and define the necessary features of this binding domain. We demonstrate that peptides derived from transthyretin bind Aβ and inhibit its toxicity. We also show that, although both transthyretin and transthyretin-derived peptides bind Aβ and inhibit toxicity, they differ significantly in their effect on Aβ aggregation.

The major pathological hallmarks of Alzheimer's disease (AD) are presence of beta-amyloid plaques surrounded by dead neurites and neurofibrillary tangles. AD brain is under tremendous oxidative stress that may be a cause or consequence of the pathology. The major familial AD-linked mutations are the mutations in amyloid precursor protein (APP) and Presinilin 1 and 2 (PS1 and 2). The most well-known mouse model to study AD is the mouse carrying human APPswe and PS1ΔE9 mutation (APP/PS1 mouse). These mice show accelerated plaque deposition. The transcription factor Nrf2 is the primary cellular defense factor against cytotoxic effects of oxidative stress. It is sequestered in the cytoplasm by Keap1 and translocate to nucleus upon oxidative insult to transcribe phase II detoxification genes. The transgenic mice were developed by crossing Nrf2 knock out (Nrf2-/-) mice to APP/PS1 mouse. The cortex, hippocampus and cerebellum were harvested from 7 mo mice for biochemistry and molecular biology. Brains were harvested for histology. We observed changes in detergent soluble and urea soluble beta-amyloid levels in APP/PS1/Nrf2-/- mice compared to APP/PS1/Nrf2+/+ mice. A significant decrease in total p62 levels was observed in cortex and hippocampus of APP/PS1/Nrf2-/- mice compared to APP/PS1/Nrf2+/+ mice. A further investigation into soluble and insoluble fraction from hippocampal tissue for p62 protein expression revealed modulation of p62 level in APP/PS1/Nrf2-/- compared to APP/PS1/Nrf2+/+ mice. There were altered poly-ubiquitin conjugated proteins levels in APP/PS1/Nrf2-/- cortex and hippocampus tissue compared to APP/PS1/Nrf2+/+ mice. SQSTM1/p62 regulates autophagic removal of ubiquitinated protein aggregates. Others have showed induction of the p62 gene by oxidative stress, which is mediated by Nrf2. In APP/PS1 mice an increase in Nrf2 and p62 was observed. In addition, Keap1 facilitates p62-mediated ubiquitin aggregate clearance via autophagy. A significant decrease in p62 in Nrf2 deficient APP/PS1 mice may be because of increased oxidative stress in addition to the lack of Nrf2. Changes in poly-ubiquitinated proteins in APP/PS1/Nrf2-/- suggests involvement of p62-Keap1-Nrf2 cascade. A further investigation is required into the pathways of beta-amyloid clearance or APP processing and behavioral changes that may have been affected by loss of Nrf2 in APP/PS1 mice.

Transthyretin (TTR) is a homotetrameric transport protein, assembled from monomers that each contain two four-stranded β-sheets and a short α-helix and loop. In the tetramer, the "inner" β-sheet forms a hydrophobic pocket while the helix and loop are solvent-exposed. β-Amyloid (Aβ) aggregates bind to TTR, and the level of binding is significantly reduced in mutants L82A (on the loop) and L110A (on the inner β-sheet). Protection against Aβ toxicity was demonstrated for wild-type TTR but not L82A or L110A, providing a direct link between TTR-Aβ binding and TTR-mediated cytoprotection. Protection is afforded at substoichiometric (1:100) TTR:Aβ molar ratios, and the level of binding of Aβ to TTR is highest for partially aggregated materials and decreased for freshly prepared or heavily aggregated Aβ, suggesting that TTR binds selectively to soluble toxic Aβ aggregates. A novel technique, nanoparticle tracking, is used to show that TTR arrests Aβ aggregation by both preventing formation of new aggregates and inhibiting growth of existing aggregates. TTR tetramers are normally quite stable; tetrameric structure is necessary for the protein's transport functions, and mutations that decrease tetramer stability have been linked to TTR amyloid diseases. However, TTR monomers bind more Aβ than do tetramers, presumably because the hydrophobic inner sheet is solvent-exposed upon tetramer disassembly. Wild-type and L110A tetramers, but not L82A, were destabilized upon being co-incubated with Aβ, suggesting that binding of Aβ to L82 triggers tetramer dissociation. Taken together, these results suggest a novel mechanism of action for TTR: the EF helix/loop "senses" the presence of soluble toxic Aβ oligomers, triggering destabilization of TTR tetramers and exposure of the hydrophobic inner sheet, which then "scavenges" these toxic oligomers and prevents them from causing cell death.

Transactive DNA-binding protein 43 (TDP-43) proteinopathy is the signature pathology of most cases of frontotemporal lobar degeneration (FTLD) and a co-morbidity in up to half of all Alzheimer's disease (AD) cases. The etiologies of TDP-43 proteinopathy are largely unknown but the presence of TDP-43 proteinopathy in AD indicates that this is a secondary effect of cellular stress/toxicity caused by AD pathology. We investigatedabeta-mediated toxicity in primary cortical neurons and APP/PS1 mice using subcellular fractionation, immunoblotting, immunofluorescence, and electron microscopy. In an A beta toxicity model in cortical neurons, we observed release of TDP-43 from the nucleus in a dose- and time-dependent manner. In comparing three-month old and nine-month old APP/PSEN1 mice, there was an age-dependent change in localization of phosphorylated TDP-43. This change in localization of phosophorylated TDP-43 also occurred prior to A beta deposition in two-month old APP/PSEN1 mice. We also undertook immunogold transmission electron microscopy (TEM) of phosphorylated TDP-43 in eight-month-old wild-type and APP/PSEN1 mice which revealed cytoplasmic accumulation of phosphorylated TDP-43 in hippocampal neurons. This cytoplasmic accumulation of TDP-43 pre-amyloid depostion in 2-month-old APP mice may indicate an early role of phosphorylated TDP-43 in response to abeta mediated stress. Whether cytoplasmic localization of TDP-43 in response to Abeta is protective or pathogenic needs further investigation.

Modulation of NF-E2 related factor 2 (Nrf2) has been shown in several neurodegenerative disorders. The overexpression of Nrf2 has become a potential therapeutic avenue for various neurodegenerative disorders such as Parkinson, Amyotrophic lateral sclerosis, and Alzheimer's disease. The expression of phase II detoxification enzymes is governed by the cis-acting regulatory element known as antioxidant response element (ARE). The transcription factor Nrf2 binds to ARE thereby transcribing multitude of antioxidant genes. Keap1, a culin 3-based E3 ligase that targets Nrf2 for degradation, sequesters Nrf2 in cytoplasm. Disruption of Keap1-Nrf2 interaction or genetic overexpression of Nrf2 can increase the endogenous antioxidant capacity of the brain thereby rendering protection against oxidative stress in neurodegenerative disorders. This review primarily focuses on recent patents that target Nrf2 overexpression as a promising therapeutic strategy for the treatment of neurodegenerative disorders.

Nuclear factor erythroid 2-related factor 2 (Nrf2) is the master transcription factor of the antioxidant response element pathway, coordinating the induction of detoxifying and antioxidant enzymes. Nrf2 is normally sequestered in the cytoplasm by Kelch-like ECH-associating protein 1 (Keap1). To identify novel small molecules that will disturb Nrf2Keap1 binding and promote activation of the Nrf2- antioxidant response element pathway, we generated a quantum model based on the structures of known Nrf2- antioxidant response element activators. We used the quantum model to perform in silico screening on over 18 million commercially available chemicals to identify the structures predicted to activate the Nrf2- antioxidant response element pathway based on the quantum model. The top hits were tested in vitro, and half of the predicted hits activated the Nrf2-antioxidant response element pathway significantly in primary cell culture. In addition, we identified a new family of Nrf2-antioxidant response element-activating structures that all have comparable activity to tBHQ and protect against oxidative stress and dopaminergic toxins in vitro. The improved ability to identify potent activators of Nrf2 through the combination of in silico and in vitro screening described here improves the speed and cost associated with screening Nrf2-antioxidant response element -activating compounds for drug development.

Proteomics analyses were performed on the brains of wild-type (WT) controls and an Alzheimer's disease (AD) mouse model, APP/PS-1 human double mutant knock-in mice. Mice were given either drinking water or water supplemented with N-acetylcysteine (NAC) (2 mg/kg body weight) for a period of five months. The time periods of treatment correspond to ages prior to A beta deposition (i.e. 4-9 months), resembling human mild cognitive impairment (MCI), and after A beta deposition (i.e. 7-12 months), more closely resembling advancing stages of AD. Substantial differences exist between the proteomes of WT and APP/PS-1 mice at 9 or 12 months, indicating that A beta deposition and oxidative stress lead to downstream changes in protein expression. Altered proteins are involved in energy-related pathways, excitotoxicity, cell cycle signaling, synaptic abnormalities, and cellular defense and structure. Overall, the proteomic results support the notion that NAC may be beneficial for increasing cellular stress responses in WT mice and for influencing the levels of energy-and mitochondria-related proteins in APP/PS-1 mice.

Adriamycin (ADR) is a chemotherapeutic for the treatment of solid tumors. This quinone-containing anthracycline is well known to produce large amounts of reactive oxygen species (ROS) in vivo. A common complaint of patients undergoing long-term treatment with ADR is somnolence, often referred to as “chemobrain.” While ADR itself does not cross the blood brain barrier (BBB), we recently showed that ADR administration causes a peripheral increase in tumor necrosis factor α (TNF-α), which migrates across the BBB and leads to inflammation and oxidative stress in brain, most likely contributing to the observed decline in cognition. In the current study, we measured levels of the antioxidant glutathione (GSH) in brains of mice injected intraparitoneally (i.p.) with ADR, as well as the levels and activities of several enzymes involved in brain GSH metabolism. We observed significantly decreased GSH levels, as well as altered GSH/GSSG ratio in brains of ADR treated mice relative to saline-treated controls. Also observed in brains of ADR treated mice were increased levels of glutathione peroxidase (GPx), glutathione-S-transferase (GST), and glutathione reductase (GR). We also observed increased activity of GPx, but a significant reduction in GST and GR activity in mice brain, 72 h post i.p. injection of ADR (20 mg/kg body weight). Furthermore, we used redox proteomics to identify specific proteins that are oxidized and/or have differential levels in mice brains as a result of a single i.p. injection of ADR. Visinin like protein 1 (VLP1), peptidyl prolyl isomerase 1 (Pin1), and syntaxin 1 (SYNT1) showed differential levels in ADR treated mice relative to saline-treated controls. Triose phosphate isomerase (TPI), enolase, and peroxiredoxin 1 (PRX-1) showed significantly increased specific carbonylation in ADR treated mice brain. These results further support the notion ADR induces oxidative stress in brain despite not crossing the BBB, and that antioxidant intervention may prevent ADR-induced cognitive dysfunction.

Alzheimer's disease (AD) is the most prevalent form of dementia among the elderly. Although the underlying cause has yet to be established, numerous data have shown that oxidative stress is implicated in AD as well as in preclinical stages of AD, such as mild cognitive impairment (MCI). The oxidative stress observed in brains of subjects with AD and MCI may be due, either fully or in part, to increased free radicals mediated by amyloid‐β peptide (Aβ). By using double human mutant APP/PS‐1 knock‐in mice as the AD model, the present work demonstrates that the APP/PS‐1 double mutation results in elevated protein oxidation (as indexed by protein carbonyls), protein nitration (as indexed by 3‐nitrotyrosine), as well as lipid peroxidation (as indexed by protein‐bound 4‐hydroxy‐2‐nonenal) in brains of mice aged 9 months and 12 months. APP/PS‐1 mice also exhibited lower levels of brain glutathione peroxidase (GPx) in both age groups studied, whereas glutathione reductase (GR) levels in brain were unaffected by the mutation. The activities of both of these antioxidant enzymes were significantly decreased in APP/PS‐1 mouse brains, whereas the activity of glucose‐6‐phosphate dehydrogenase (G6PDH) was increased relative to controls in both age groups. Levels of peptidyl prolyl isomerase 1 (Pin1) were significantly decreased in APP/PS‐1 mouse brain aged 9 and 12 months. Administration of N‐acetyl‐L‐cysteine (NAC), a glutathione precursor, to APP/PS‐1 mice via drinking water suppressed increased protein oxidation and nitration and also significantly augmented levels and activity of GPx in brain from both age groups. Oral administration of NAC also increased the diminished activity of GR and protected against lipid peroxidation in brains of 9‐month‐old APP/PS‐1 mice only. Pin1 levels, GR levels, and G6PDH activity in brain were unaffected by oral administration of NAC in both age groups. These results are discussed with reference to the therapeutic potential of this brain‐accessible glutathione precursor in the treatment of MCI and AD. © 2010 Wiley‐Liss, Inc.

Quercetin, a flavonoid found in various foodstuffs, has antioxidant properties and increases glutathione (GSH) levels and antioxidant enzyme function. Considerable attention has been focused on increasing the intracellular GSH levels in many diseases, including Alzheimer's disease (AD). Amyloid beta-peptide [Aβ(1–42)], elevated in AD brain, is associated with oxidative stress and neurotoxicity. We aimed to investigate the protective effects of quercetin on Aβ(1–42)-induced oxidative cell toxicity in cultured neurons in the present study. Decreased cell survival in neuronal cultures treated with Aβ(1–42) correlated with increased free radical production measured by dichlorofluorescein fluorescence and an increase in protein oxidation (protein carbonyl, 3-nitrotyrosine) and lipid peroxidation (protein-bound 4-hydroxy-2-nonenal). Pretreatment of primary hippocampal cultures with quercetin significantly attenuated Aβ(1–42)-induced cytotoxicity, protein oxidation, lipid peroxidation and apoptosis. A dose–response study suggested that quercetin showed protective effects against Aβ(1–42) toxicity by modulating oxidative stress at lower doses, but higher doses were not only non-neuroprotective but also toxic. These findings provide motivation to test the hypothesis that quercetin may provide a promising approach for the treatment of AD and other oxidative-stress-related neurodegenerative diseases.

Aging and age-related disorders such as Alzheimer's disease (AD) are usually accompanied by oxidative stress as one of the main mechanisms contributing to neurodegeneration and cognitive decline. Aging canines develop cognitive dysfunction and neuropathology similar to those seen in humans, and the use of antioxidants results in reductions in oxidative damage and in improvement in cognitive function in this canine model of human aging. In the present study, the effect of a long-term treatment with an antioxidant-fortified diet and a program of behavioral enrichment on oxidative damage was studied in aged canines. To identify the neurobiological mechanisms underlying these treatment effects, the parietal cortex from 23 beagle dogs (8.1-12.4 years) were treated for 2.8 years in one of four treatment groups: i.e., control food-control behavioral enrichment (CC); control food-behavioral enrichment (CE); antioxidant food-control behavioral enrichment (CA); enriched environment-antioxidant-fortified food (EA). We analyzed the levels of the oxidative stress biomarkers, i.e., protein carbonyls, 3-nitrotyrosine (3-NT), and the lipid peroxidation product, 4-hydroxynonenal (HNE), and observed a decrease in their levels on all treatments when compared to control, with the most significant effects found in the combined treatment, EA. Since EA treatment was most effective, we also carried out a comparative proteomics study to identify specific brain proteins that were differentially expressed and used a parallel redox proteomics approach to identify specific brain proteins that were less oxidized following EA. The specific protein carbonyl levels of glutamate dehydrogenase [NAD (P)], glyceraldehyde-3-phosphate dehydrogenase (GAPDH), alpha-enolase, neurofilament triplet L protein, glutathione-S-transferase (GST) and fascin actin bundling protein were significantly reduced in brain of EA-treated dogs compared to control. We also observed significant increases in expression of Cu/Zn superoxide dismutase, fructose-bisphosphate aldolase C, creatine kinase, glutamate dehydrogenase and glyceraldehyde-3-phosphate dehydrogenase. The increased expression of these proteins and in particular Cu/Zn SOD correlated with improved cognitive function. In addition, there was a significant increase in the enzymatic activities of glutathione-S-transferase (GST) and total superoxide dismutase (SOD), and significant increase in the protein levels of heme oxygenase (HO-1) in EA treated dogs compared to control. These findings suggest that the combined treatment reduces the levels of oxidative damage and improves the antioxidant reserve systems in the aging canine brain, and may contribute to improvements in learning and memory. These observations provide insights into a possible neurobiological mechanism underlying the effects of the combined treatment. These results support the combination treatments as a possible therapeutic approach that could be translated to the aging human population who are at risk for age-related neurodegenerative disorders, including Alzheimer's disease.

Considerable evidence supports the role of oxidative stress in the pathogenesis of Alzheimer’s disease. One hallmark of Alzheimer’s disease is the accumulation of amyloid β-peptide, which invokes a cascade of oxidative damage to neurons that can eventually result in neuronal death. Amyloid β-peptide is the main component of senile plaques and generates free radicals ultimately leading to neuronal damage of membrane lipids, proteins and nucleic acids. Therefore, interest in the protective role of different antioxidant compounds has been growing for treatment of Alzheimer’s disease and other oxidative stress-related disorders. Among different antioxidant drugs, much interest has been devoted to “thiol-delivering” compounds. Tricyclodecan-9-yl-xanthogenate is an inhibitor of phosphatidylcholine specific phospholipase C, and recent studies reported its ability to act as a glutathione-mimetic compound. In the present study, we investigate the in vivo ability of tricyclodecan-9-yl-xanthogenate to protect synaptosomes against amyloid β-peptide-induced oxidative stress. Gerbils were injected i.p. with tricyclodecan-9-yl-xanthogenate or with saline solution, and synaptosomes were isolated from the brain. Synaptosomal preparations isolated from tricyclodecan-9-yl-xanthogenate injected gerbils and treated ex vivo with amyloid β-peptide (1–42) showed a significant decrease of oxidative stress parameters: reactive oxygen species levels, protein oxidation (protein carbonyl and 3-nitrotyrosine levels) and lipid peroxidation (4-hydroxy-2-nonenal levels). Our results are consistent with the hypothesis that modulation of free radicals generated by amyloid β-peptide might represent an efficient therapeutic strategy for treatment of Alzheimer’s disease and other oxidative-stress related disorders. Based on the above data, we suggest that tricyclodecan-9-yl-xanthogenate is a potent antioxidant and could be of importance for the treatment of Alzheimer’s disease and other oxidative stress-related disorders.

Proteolytic processing and phosphorylation of amyloid precursor protein (APP), and hyperphosphorylation of tau protein, have been shown to be increased in Alzheimer's disease (AD) brains, leading to increased production of beta-amyloid (A beta) peptides and neurofibrillary tangles, respectively. These observations suggest that phosphorylation events are critical to the understanding of the pathogenesis and treatment of this devastating disease. Pin-1, one of the peptidyl-prolyl isomerases (PPIase), catalyzes the isomerization of the peptide bond between pSer/Thr-Pro in proteins, thereby regulating their biological functions which include protein assembly, folding, intracellular transport, intracellular signaling, transcription, cell cycle progression and apoptosis. A number of previous studies have shown that Pin1 is co-localized with phosphorylated tau in AD brain, and shows an inverse relationship to the expression of tau. Pin1 protects neurons under in vitro conditions. Moreover, recent studies demonstrate that APP is a target for Pin1 and thus, in A beta production. Furthermore, Pin1 was found to be oxidatively modified and to have reduced activity in the hippocampus in mild cognitive impairment (MCI) and AD. Because of the diverse functions of Pin1, and the discovery that this protein is one of the oxidized proteins common to both MCI and AD brain, the question arises as to whether Pin1 is one of the driving forces for the initiation or progression of AD pathogenesis, finally leading to neurodegeneration and neuronal apoptosis. In the present review, we discuss the role of Pin1 with respect to Alzheimer's disease.

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the deposition of amyloid-beta peptide (Abeta), a peptide that as both oligomers and fibrils is believed to play a central role in the development and progress of AD by inducing oxidative stress in brain. Therefore, treatment with antioxidants might, in principle, prevent propagation of tissue damage and neurological dysfunction. The aim of the present study was to investigate the in vivo protective effect of the antioxidant compound ferulic acid ethyl ester (FAEE) against Abeta-induced oxidative damage on isolated synaptosomes. Gerbils were injected intraperitoneally (i.p.) with FAEE or with dimethylsulfoxide, and synaptosomes were isolated from the brain. Synaptosomes isolated from FAEE-injected gerbils and then treated ex vivo with Abeta(1-42) showed a significant decrease in oxidative stress parameters: reactive oxygen species levels, protein oxidation (protein carbonyl and 3-nitrotyrosine levels), and lipid peroxidation (4-hydroxy-2-nonenal levels). Consistent with these results, both FAEE and Abeta(1-42) increased levels of antioxidant defense systems, evidenced by increased levels of heme oxygenase 1 and heat shock protein 72. FAEE led to decreased levels of inducible nitric oxide synthase. These results are discussed with potential therapeutic implications of FAEE, a brain accessible, multifunctional antioxidant compound, for AD involving modulation of free radicals generated by Abeta.

Oxidative stress in heart and brain by the cancer chemotherapeutic drug adriamycin (ADR), used for treating solid tumors, is well established. Long-term treatment with ADR in breast cancer patients has led to symptoms of cardiomyopathy. Less well recognized, but increasingly well documented, is cognitive dysfunction. After chemotherapy, free radical-mediated oxidative stress has been reported in both heart and brain. We recently showed a significant increase in protein oxidation and lipid peroxidation in brain isolated from mice injected intraperitonially (i.p) with ADR. Systemic administration of ADR also induces tumor necrosis factor-alpha (TNF-alpha), which leads to production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in brain. Circulating TNF also causes mitochondrial dysfunction, leading to apoptotic pathways in brain. Inducible nitric oxide synthase also plays a role in ADR-induced TNF-mediated neurotoxicity. In addition, we previously showed a significant decrease in glutathione (GSH) levels in brain isolated from ADR injected mice, along with increased expression of multidrug-resistant protein-1 (MRP-1), glutathione-S-transferase (GST), glutathione peroxidase (GPx), and glutathione reductase (GR). There was a significant decrease in activity of brain GST. The present study was designed to test the hypothesis that, by elevating brain levels of GSH, the brain would be protected against oxidative stress in ADR-injected mice. gamma-Glutamyl cysteine ethyl ester (GCEE), a precursor of glutathione, injected i.p. (150 mg/ kg body weight) 4 hr prior ADR injection (20 mg/kg body weight) led to significantly decreased protein oxidation and lipid peroxidation in subsequently isolated mice brain compared with brain isolated from ADR-injected mice without GCEE. The GSH levels were restored to the level of brain isolated from saline-injected mice. Furthermore, the enzyme activity of GST was increased in brain isolated from ADR-injected mice previously injected with GCEE compared with the brain isolated from ADR-injected mice previously injected with saline. These results are discussed with regard to potential pharmacological prevention of brain cognitive dysfunction in patients receiving ADR chemotherapy.

Abstract Proteolytic processing and phosphorylation of amyloid precursor protein (APP), and hyperphosphorylation of tau protein, have been shown to be increased in Alzheimer's disease (AD) brains, leading to increased production of β‐amyloid (Aβ) peptides and neurofibrillary tangles, respectively. These observations suggest that phosphorylation events are critical to the understanding of the pathogenesis and treatment of this devastating disease. Pin‐1, one of the peptidyl‐prolyl isomerases (PPIase), catalyzes the isomerization of the peptide bond between pSer/Thr‐Pro in proteins, thereby regulating their biological functions which include protein assembly, folding, intracellular transport, intracellular signaling, transcription, cell cycle progression and apoptosis. A number of previous studies have shown that Pin1 is co‐localized with phosphorylated tau in AD brain, and shows an inverse relationship to the expression of tau. Pin1 protects neurons under in vitro conditions. Moreover, recent studies demonstrate that APP is a target for Pin1 and thus, in Aβ production. Furthermore, Pin1 was found to be oxidatively modified and to have reduced activity in the hippocampus in mild cognitive impairment (MCI) and AD. Because of the diverse functions of Pin1, and the discovery that this protein is one of the oxidized proteins common to both MCI and AD brain, the question arises as to whether Pin1 is one of the driving forces for the initiation or progression of AD pathogenesis, finally leading to neurodegeneration and neuronal apoptosis. In the present review, we discuss the role of Pin1 with respect to Alzheimer's disease.