scholarly journals Redox-Active Metal Ions and Amyloid-Degrading Enzymes in Alzheimer’s Disease

2021 ◽  
Vol 22 (14) ◽  
pp. 7697
Author(s):  
Namdoo Kim ◽  
Hyuck Jin Lee
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Metal Ions ◽  
Normal Brain ◽  
Insulin Degrading Enzyme ◽  
Degrading Enzymes ◽  
Redox Active ◽  
Active Metal ◽  
The Brain ◽  
Redox Active Metal

Redox-active metal ions, Cu(I/II) and Fe(II/III), are essential biological molecules for the normal functioning of the brain, including oxidative metabolism, synaptic plasticity, myelination, and generation of neurotransmitters. Dyshomeostasis of these redox-active metal ions in the brain could cause Alzheimer’s disease (AD). Thus, regulating the levels of Cu(I/II) and Fe(II/III) is necessary for normal brain function. To control the amounts of metal ions in the brain and understand the involvement of Cu(I/II) and Fe(II/III) in the pathogenesis of AD, many chemical agents have been developed. In addition, since toxic aggregates of amyloid-β (Aβ) have been proposed as one of the major causes of the disease, the mechanism of clearing Aβ is also required to be investigated to reveal the etiology of AD clearly. Multiple metalloenzymes (e.g., neprilysin, insulin-degrading enzyme, and ADAM10) have been reported to have an important role in the degradation of Aβ in the brain. These amyloid degrading enzymes (ADE) could interact with redox-active metal ions and affect the pathogenesis of AD. In this review, we introduce and summarize the roles, distributions, and transportations of Cu(I/II) and Fe(II/III), along with previously invented chelators, and the structures and functions of ADE in the brain, as well as their interrelationships.

scholarly journals Hypothesis: Soluble AβOligomers in Association with Redox-Active Metal Ions Are the Optimal Generators of Reactive Oxygen Species in Alzheimer's Disease

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Brian J. Tabner ◽  
Jennifer Mayes ◽  
David Allsop
Keyword(s):  
Alzheimer’S Disease ◽  
Reactive Oxygen Species ◽  
Alzheimer's Disease ◽  
Hydrogen Peroxide ◽  
Metal Ions ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Redox Active ◽  
Active Metal ◽  
Redox Active Metal

Considerable evidence points to oxidative stress in the brain as an important event in the early stages of Alzheimer's disease (AD). The transition metal ions of Cu, Fe, and Zn are all enriched in the amyloid cores of senile plaques in AD. Those of Cu and Fe are redox active and bind to Aβin vitro. When bound, they can facilitate the reduction of oxygen to hydrogen peroxide, and of the latter to the hydroxyl radical. This radical is very aggressive and can cause considerable oxidative damage. Recent research favours the involvement of small, soluble oligomers as the aggregating species responsible for Aβ neurotoxicity. We propose that the generation of reactive oxygen species (i.e., hydrogen peroxide and hydroxyl radicals) by these oligomers, in association with redox-active metal ions, is a key molecular mechanism underlying the pathogenesis of AD and some other neurodegenerative disorders.

scholarly journals Cognitive and Disease-Modifying Effects of 11β-Hydroxysteroid Dehydrogenase Type 1 Inhibition in Male Tg2576 Mice, a Model of Alzheimer's Disease

Endocrinology ◽  
2015 ◽  
Vol 156 (12) ◽  
pp. 4592-4603 ◽  
Author(s):  
Karen Sooy ◽  
June Noble ◽  
Andrew McBride ◽  
Margaret Binnie ◽  
Joyce L. W. Yau ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Decline ◽  
Hydroxysteroid Dehydrogenase ◽  
Insulin Degrading Enzyme ◽  
Short Term Treatment ◽  
Model Of Alzheimer’S Disease ◽  
The Brain ◽  
Tg2576 Mice

Chronic exposure to elevated levels of glucocorticoids has been linked to age-related cognitive decline and may play a role in Alzheimer's disease. In the brain, 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) amplifies intracellular glucocorticoid levels. We show that short-term treatment of aged, cognitively impaired C57BL/6 mice with the potent and selective 11β-HSD1 inhibitor UE2316 improves memory, including after intracerebroventricular drug administration to the central nervous system alone. In the Tg2576 mouse model of Alzheimer's disease, UE2316 treatment of mice aged 14 months for 4 weeks also decreased the number of β-amyloid (Aβ) plaques in the cerebral cortex, associated with a selective increase in local insulin-degrading enzyme (involved in Aβ breakdown and known to be glucocorticoid regulated). Chronic treatment of young Tg2576 mice with UE2316 for up to 13 months prevented cognitive decline but did not prevent Aβ plaque formation. We conclude that reducing glucocorticoid regeneration in the brain improves cognition independently of reduced Aβ plaque pathology and that 11β-HSD1 inhibitors have potential as cognitive enhancers in age-associated memory impairment and Alzheimer's dementia.

scholarly journals he amyloid hypothesis of Alzheimer's disease: past and present, hopes and disappointments

2019 ◽  
Vol 11 (3) ◽  
pp. 4-10
Author(s):  
I. V. Litvinenko ◽  
A. Yu. Emelin ◽  
V. Yu. Lobzin ◽  
K. A. Kolmakova ◽  
K. M. Naumov ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Clinical Signs ◽  
Passive Immunization ◽  
Amyloid Hypothesis ◽  
Amyloid Deposits ◽  
Redox Active ◽  
Protein Overproduction ◽  
The Brain

In 1887, S.A. Belyakov, a physician of the Imperial Medical and Surgical Academy, first described amyloid deposits in the brain of patients with dementia. Later, in 1906, A. Alzheimer revealed amyloid plaques and tau tangles in a patient with clinical signs of dementia. Over the following 100 years, the development of the concept of the amyloid origin of Alzheimer's disease (AD) confirmed numerous relationships between the brain accumulation of APs and cognitive decline. And if at the beginning of the amyloid era many researchers considered that the disease was caused by amyloid beta (Aβ) protein overproduction, in recent years they have increasingly pointed to a defect in the mechanisms of Aβ clearance, especially after the discovery of the lymphatic system of the brain. The role of disturbed homeostasis of redox-active metals, primarily iron and copper, in the development of the disease is also considered.The amyloid hypothesis of AD has served as the basis for several areas in the design of drugs, such as secretase inhibitors, immunomodulatory drugs for active and passive immunization. However, only one drug (Akatinol memantine, an inhibitor of NMDA receptors and glutamatergic excitotoxicity) for the treatment of AD has been introduced into clinical practice over the past 20 years. Of interest are the data obtained in new studies of Akatinol memantine, which suggest that the latter is able to some extent affect the main pathophysiological processes underlying the development of cognitive impairment in Alzheimer-type pathology. 

scholarly journals Mechanisms of Brain Aging Regulation by Insulin: Implications for Neurodegeneration in Late-Onset Alzheimer's Disease

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Artur F. Schuh ◽  
Carlos M. Rieder ◽  
Liara Rizzi ◽  
Márcia Chaves ◽  
Matheus Roriz-Cruz
Keyword(s):  
Alzheimer’S Disease ◽  
Insulin Resistance ◽  
Alzheimer's Disease ◽  
Brain Aging ◽  
Late Onset ◽  
Energy Deficit ◽  
Insulin Degrading Enzyme ◽  
Microvascular Endothelium ◽  
Chronic Hyperglycemia ◽  
The Brain

Insulin and IGF seem to be important players in modulating brain aging. Neurons share more similarities with islet cells than any other human cell type. Insulin and insulin receptors are diffusely found in the brain, especially so in the hippocampus. Caloric restriction decreases insulin resistance, and it is the only proven mechanism to expand lifespan. Conversely, insulin resistance increases with age, obesity, and sedentarism, all of which have been shown to be risk factors for late-onset Alzheimer's disease (AD). Hyperphagia and obesity potentiate the production of oxidative reactive species (ROS), and chronic hyperglycemia accelerates the formation of advanced glucose end products (AGEs) in (pre)diabetes—both mechanisms favoring a neurodegenerative milieu. Prolonged high cerebral insulin concentrations cause microvascular endothelium proliferation, chronic hypoperfusion, and energy deficit, triggering β-amyloid oligomerization and tau hyperphosphorylation. Insulin-degrading enzyme (IDE) seems to be the main mechanism in clearing β-amyloid from the brain. Hyperinsulinemic states may deviate IDE utilization towards insulin processing, decreasing β-amyloid degradation.

scholarly journals Characterization of Brain Iron Deposition Pattern and Its Association With Genetic Risk Factor in Alzheimer’s Disease Using Susceptibility-Weighted Imaging

2021 ◽  
Vol 15 ◽  
Author(s):  
Peiting You ◽  
Xiang Li ◽  
Zhijiang Wang ◽  
Huali Wang ◽  
Bin Dong ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Association Studies ◽  
Iron Deposition ◽  
Susceptibility Weighted Imaging ◽  
Normal Brain ◽  
Brain Iron ◽  
Brain Functions ◽  
The Brain ◽  
Brain Iron Deposition

The presence of iron is an important factor for normal brain functions, whereas excessive deposition of iron may impair normal cognitive function in the brain and lead to Alzheimer’s disease (AD). MRI has been widely applied to characterize brain structural and functional changes caused by AD. However, the effectiveness of using susceptibility-weighted imaging (SWI) for the analysis of brain iron deposition is still unclear, especially within the context of early AD diagnosis. Thus, in this study, we aim to explore the relationship between brain iron deposition measured by SWI with the progression of AD using various feature selection and classification methods. The proposed model was evaluated on a 69-subject SWI imaging dataset consisting of 24 AD patients, 21 mild cognitive impairment patients, and 24 normal controls. The identified AD progression-related regions were then compared with the regions reported from previous genetic association studies, and we observed considerable overlap between these two. Further, we have identified a new potential AD-related gene (MEF2C) closely related to the interaction between iron deposition and AD progression in the brain.

scholarly journals Metformin Ameliorates Aβ Pathology by Insulin-Degrading Enzyme in a Transgenic Mouse Model of Alzheimer’s Disease

2020 ◽  
Vol 2020 ◽  
pp. 1-10 ◽  
Author(s):  
Xin-Yi Lu ◽  
Shun Huang ◽  
Qu-Bo Chen ◽  
Dapeng Zhang ◽  
Wanyan Li ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Transgenic Mice ◽  
Mrna Expression ◽  
Insulin Degrading Enzyme ◽  
Antidiabetic Drug ◽  
Degrading Enzyme ◽  
Expression Levels ◽  
The Brain ◽  
Mrna Expression Levels

Alzheimer’s disease (AD) is the most common neurodegenerative disease. The accumulation of amyloid beta (Aβ) is the main pathology of AD. Metformin, a well-known antidiabetic drug, has been reported to have AD-protective effect. However, the mechanism is still unclear. In this study, we tried to figure out whether metformin could activate insulin-degrading enzyme (IDE) to ameliorate Aβ-induced pathology. Morris water maze and Y-maze results indicated that metformin could improve the learning and memory ability in APPswe/PS1dE9 (APP/PS1) transgenic mice. 18F-FDG PET-CT result showed that metformin could ameliorate the neural dysfunction in APP/PS1 transgenic mice. PCR analysis showed that metformin could effectively improve the mRNA expression level of nerve and synapse-related genes (Syp, Ngf, and Bdnf) in the brain. Metformin decreased oxidative stress (malondialdehyde and superoxide dismutase) and neuroinflammation (IL-1β and IL-6) in APP/PS1 mice. In addition, metformin obviously reduced the Aβ level in the brain of APP/PS1 mice. Metformin did not affect the enzyme activities and mRNA expression levels of Aβ-related secretases (ADAM10, BACE1, and PS1). Meanwhile, metformin also did not affect the mRNA expression levels of Aβ-related transporters (LRP1 and RAGE). Metformin increased the protein levels of p-AMPK and IDE in the brain of APP/PS1 mice, which might be the key mechanism of metformin on AD. In conclusion, the well-known antidiabetic drug, metformin, could be a promising drug for AD treatment.

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