TDP-43 Pathology in Alzheimer’s Disease

AbstractTransactive response DNA binding protein of 43 kDa (TDP-43) is an intranuclear protein encoded by the TARDBP gene that is involved in RNA splicing, trafficking, stabilization, and thus, the regulation of gene expression. Cytoplasmic inclusion bodies containing phosphorylated and truncated forms of TDP-43 are hallmarks of amyotrophic lateral sclerosis (ALS) and a subset of frontotemporal lobar degeneration (FTLD). Additionally, TDP-43 inclusions have been found in up to 57% of Alzheimer’s disease (AD) cases, most often in a limbic distribution, with or without hippocampal sclerosis. In some cases, TDP-43 deposits are also found in neurons with neurofibrillary tangles. AD patients with TDP-43 pathology have increased severity of cognitive impairment compared to those without TDP-43 pathology. Furthermore, the most common genetic risk factor for AD, apolipoprotein E4 (APOE4), is associated with increased frequency of TDP-43 pathology. These findings provide strong evidence that TDP-43 pathology is an integral part of multiple neurodegenerative conditions, including AD. Here, we review the biology and pathobiology of TDP-43 with a focus on its role in AD. We emphasize the need for studies on the mechanisms that lead to TDP-43 pathology, especially in the setting of age-related disorders such as AD.

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Mitophagy in Alzheimer’s Disease and Other Age-Related Neurodegenerative Diseases

Cells ◽

10.3390/cells9010150 ◽

2020 ◽

Vol 9 (1) ◽

pp. 150 ◽

Cited By ~ 20

Author(s):

Qian Cai ◽

Yu Young Jeong

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Neurodegenerative Diseases ◽

Molecular Mechanisms ◽

Therapeutic Potential ◽

Cellular Energy ◽

Age Related ◽

Mitochondrial Turnover ◽

Neuronal Functions ◽

Lateral Sclerosis

Mitochondrial dysfunction is a central aspect of aging and neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, and Huntington’s disease. Mitochondria are the main cellular energy powerhouses, supplying most of ATP by oxidative phosphorylation, which is required to fuel essential neuronal functions. Efficient removal of aged and dysfunctional mitochondria through mitophagy, a cargo-selective autophagy, is crucial for mitochondrial maintenance and neuronal health. Mechanistic studies into mitophagy have highlighted an integrated and elaborate cellular network that can regulate mitochondrial turnover. In this review, we provide an updated overview of the recent discoveries and advancements on the mitophagy pathways and discuss the molecular mechanisms underlying mitophagy defects in Alzheimer’s disease and other age-related neurodegenerative diseases, as well as the therapeutic potential of mitophagy-enhancing strategies to combat these disorders.

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Alzheimer's Disease Including Focal Presentations

Seminars in Neurology ◽

10.1055/s-0039-1681041 ◽

2019 ◽

Vol 39 (02) ◽

pp. 213-226 ◽

Cited By ~ 8

Author(s):

Nicolas Villain ◽

Bruno Dubois

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Medial Temporal Lobe ◽

Chronic Traumatic Encephalopathy ◽

Hippocampal Sclerosis ◽

Clinical Status ◽

Lewy Body Disease ◽

Epidemiological Data ◽

Cortical Atrophy ◽

Age Related

AbstractAlzheimer's disease (AD) is the commonest neurodegenerative disease and the most frequent cause of dementia. It affects 30 million people worldwide. Current research criteria focus on biomarkers' status for amyloid and tau using positron emission tomography and cerebrospinal fluid analysis, independent of clinical status. Current epidemiological data, which mostly rely on biomarker-undetermined AD cases, have highlighted ApoE4 and age as the main risk factors. Rare autosomal dominant mutations also account for a small fraction of early-onset AD. The main clinical phenotype at presentation is the amnestic phenotype targeting episodic memory. This is followed by rarer phenotypes such as posterior cortical atrophy, logopenic variant of primary progressive aphasia, frontal variant AD, corticobasal syndrome, and other even rarer presentations mimicking language variants of frontotemporal dementia. Main differential diagnoses include hippocampal sclerosis with TDP-43, primary age-related tauopathy, argyrophilic grain disease, frontotemporal lobar degeneration, Lewy body disease, chronic traumatic encephalopathy as well as nondegenerative disorders such as cerebrovascular disease, chronic alcohol consumption, limbic encephalitis, medial temporal lobe epilepsy, and others. Co-occurrence of AD pathology with other neurodegenerative and vascular diseases is common and increases with age. This presents a challenge in current clinical practice due to a lack of reliable biomarkers for non-AD neurodegenerative diseases.

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Defective Autophagy and Mitophagy in Aging and Alzheimer’s Disease

Frontiers in Neuroscience ◽

10.3389/fnins.2020.612757 ◽

2021 ◽

Vol 14 ◽

Author(s):

Michael Tran ◽

P. Hemachandra Reddy

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Mitochondrial Dysfunction ◽

Physiological Function ◽

Mitochondrial Dynamics ◽

Age Factors ◽

Age Related ◽

Living Organisms ◽

Physiological Markers ◽

Lateral Sclerosis

Aging is the time-dependent process that all living organisms go through characterized by declining physiological function due to alterations in metabolic and molecular pathways. Many decades of research have been devoted to uncovering the cellular changes and progression of aging and have revealed that not all organisms with the same chronological age exhibit the same age-related declines in physiological function. In assessing biological age, factors such as epigenetic changes, telomere length, oxidative damage, and mitochondrial dysfunction in rescue mechanisms such as autophagy all play major roles. Recent studies have focused on autophagy dysfunction in aging, particularly on mitophagy due to its major role in energy generation and reactive oxidative species generation of mitochondria. Mitophagy has been implicated in playing a role in the pathogenesis of many age-related diseases, including Alzheimer’s disease (AD), Parkinson’s, Huntington’s, and amyotrophic lateral sclerosis. The purpose of our article is to highlight the mechanisms of autophagy and mitophagy and how defects in these pathways contribute to the physiological markers of aging and AD. This article also discusses how mitochondrial dysfunction, abnormal mitochondrial dynamics, impaired biogenesis, and defective mitophagy are related to aging and AD progression. This article highlights recent studies of amyloid beta and phosphorylated tau in relation to autophagy and mitophagy in AD.

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Is it Alzheimer's disease, or age-related memory problems?

PsycEXTRA Dataset ◽

10.1037/e435022008-007 ◽

2000 ◽

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Memory Problems ◽

Age Related

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Emerging Promise of Immunotherapy for Alzheimer’s Disease: A New Hope for the Development of Alzheimer’s Vaccine

Current Topics in Medicinal Chemistry ◽

10.2174/1568026620666200422105156 ◽

2020 ◽

Vol 20 (13) ◽

pp. 1214-1234 ◽

Cited By ~ 4

Author(s):

Md. Tanvir Kabir ◽

Md. Sahab Uddin ◽

Bijo Mathew ◽

Pankoj Kumar Das ◽

Asma Perveen ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Immune Response ◽

Neutralizing Antibodies ◽

Neurodegenerative Disorder ◽

Symptomatic Relief ◽

Aβ Oligomers ◽

Th2 Immune Response ◽

Age Related ◽

Anti Inflammatory

Background: Alzheimer's disease (AD) is a chronic neurodegenerative disorder and the characteristics of this devastating disorder include the progressive and disabling deficits in the cognitive functions including reasoning, attention, judgment, comprehension, memory, and language. Objective: In this article, we have focused on the recent progress that has been achieved in the development of an effective AD vaccine. Summary: Currently, available treatment options of AD are limited to deliver short-term symptomatic relief only. A number of strategies targeting amyloid-beta (Aβ) have been developed in order to treat or prevent AD. In order to exert an effective immune response, an AD vaccine should contain adjuvants that can induce an effective anti-inflammatory T helper 2 (Th2) immune response. AD vaccines should also possess the immunogens which have the capacity to stimulate a protective immune response against various cytotoxic Aβ conformers. The induction of an effective vaccine’s immune response would necessitate the parallel delivery of immunogen to dendritic cells (DCs) and their priming to stimulate a Th2-polarized response. The aforesaid immune response is likely to mediate the generation of neutralizing antibodies against the neurotoxic Aβ oligomers (AβOs) and also anti-inflammatory cytokines, thus preventing the AD-related inflammation. Conclusion: Since there is an age-related decline in the immune functions, therefore vaccines are more likely to prevent AD instead of providing treatment. AD vaccines might be an effective and convenient approach to avoid the treatment-related huge expense.

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Two human metabolites rescue a C. elegans model of Alzheimer’s disease via a cytosolic unfolded protein response

Communications Biology ◽

10.1038/s42003-021-02218-7 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Priyanka Joshi ◽

Michele Perni ◽

Ryan Limbocker ◽

Benedetta Mannini ◽

Sam Casford ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Unfolded Protein Response ◽

Neurodegenerative Disorders ◽

C Elegans ◽

Unfolded Protein ◽

Model Of Alzheimer’S Disease ◽

Age Related ◽

Parkinson’S Diseases ◽

Protein Response

AbstractAge-related changes in cellular metabolism can affect brain homeostasis, creating conditions that are permissive to the onset and progression of neurodegenerative disorders such as Alzheimer’s and Parkinson’s diseases. Although the roles of metabolites have been extensively studied with regard to cellular signaling pathways, their effects on protein aggregation remain relatively unexplored. By computationally analysing the Human Metabolome Database, we identified two endogenous metabolites, carnosine and kynurenic acid, that inhibit the aggregation of the amyloid beta peptide (Aβ) and rescue a C. elegans model of Alzheimer’s disease. We found that these metabolites act by triggering a cytosolic unfolded protein response through the transcription factor HSF-1 and downstream chaperones HSP40/J-proteins DNJ-12 and DNJ-19. These results help rationalise previous observations regarding the possible anti-ageing benefits of these metabolites by providing a mechanism for their action. Taken together, our findings provide a link between metabolite homeostasis and protein homeostasis, which could inspire preventative interventions against neurodegenerative disorders.

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Tau and TDP-43 synergy: a novel therapeutic target for sporadic late-onset Alzheimer’s disease

GeroScience ◽

10.1007/s11357-021-00407-0 ◽

2021 ◽

Author(s):

Caitlin S. Latimer ◽

Nicole F. Liachko

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Late Onset ◽

Hippocampal Sclerosis ◽

Model Organism ◽

Amyloid Β ◽

Underlying Disease ◽

Therapeutic Interventions ◽

Disease Biology ◽

Rapid Cognitive Decline

AbstractAlzheimer’s disease (AD) is traditionally defined by the presence of two types of protein aggregates in the brain: amyloid plaques comprised of the protein amyloid-β (Aβ) and neurofibrillary tangles containing the protein tau. However, a large proportion (up to 57%) of AD patients also have TDP-43 aggregates present as an additional comorbid pathology. The presence of TDP-43 aggregates in AD correlates with hippocampal sclerosis, worse brain atrophy, more severe cognitive impairment, and more rapid cognitive decline. In patients with mixed Aβ, tau, and TDP-43 pathology, TDP-43 may interact with neurodegenerative processes in AD, worsening outcomes. While considerable progress has been made to characterize TDP-43 pathology in AD and late-onset dementia, there remains a critical need for mechanistic studies to understand underlying disease biology and develop therapeutic interventions. This perspectives article reviews the current understanding of these processes from autopsy cohort studies and model organism-based research, and proposes targeting neurotoxic synergies between tau and TDP-43 as a new therapeutic strategy for AD with comorbid TDP-43 pathology.

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A novel orally active HDAC6 inhibitor T-518 shows a therapeutic potential for Alzheimer’s disease and tauopathy in mice

Scientific Reports ◽

10.1038/s41598-021-94923-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Tomohiro Onishi ◽

Ryouta Maeda ◽

Michiko Terada ◽

Sho Sato ◽

Takahiro Fujii ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Therapeutic Potential ◽

Drug Candidate ◽

Histone Deacetylase 6 ◽

Cellular Assays ◽

Age Related ◽

Acetylation State ◽

Hdac6 Inhibitor ◽

Orally Active

AbstractAccumulation of tau protein is a key pathology of age-related neurodegenerative diseases such as Alzheimer's disease and progressive supranuclear palsy. Those diseases are collectively termed tauopathies. Tau pathology is associated with axonal degeneration because tau binds to microtubules (MTs), a component of axon and regulates their stability. The acetylation state of MTs contributes to stability and histone deacetylase 6 (HDAC6) is a major regulator of MT acetylation status, suggesting that pharmacological HDAC6 inhibition could improve axonal function and may slow the progression of tauopathy. Here we characterize N-[(1R,2R)-2-{3-[5-(difluoromethyl)-1,3,4-oxadiazol-2-yl]-5-oxo-5H,6H,7H-pyrrolo[3,4-b]pyridin-6-yl}cyclohexyl]-2,2,3,3,3-pentafluoropropanamide (T-518), a novel, potent, highly selective HDAC6 inhibitor with clinically favorable pharmacodynamics. T-518 shows potent inhibitory activity against HDAC6 and superior selectivity over other HDACs compared with the known HDAC6 inhibitors in the enzyme and cellular assays. T-518 showed brain penetration in an oral dose and blocked HDAC6-dependent tubulin deacetylation at Lys40 in mouse hippocampus. A 2-week treatment restored impaired axonal transport and novel object recognition in the P301S tau Tg mouse, tauopathy model, while a 3-month treatment also decreased RIPA-insoluble tau accumulation. Pharmaceutical inhibition of HDAC6 is a potential therapeutic strategy for tauopathy, and T-518 is a particularly promising drug candidate.

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Probable Causes of Alzheimer’s Disease

Sci ◽

10.3390/sci3010016 ◽

2021 ◽

Vol 3 (1) ◽

pp. 16

Author(s):

James David Adams

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Lactic Acid ◽

Blood Brain Barrier ◽

Transient Receptor Potential ◽

Brain Barrier ◽

Folate Intake ◽

Blood Brain ◽

Age Related ◽

The Brain

A three-part mechanism is proposed for the induction of Alzheimer’s disease: (1) decreased blood lactic acid; (2) increased blood ceramide and adipokines; (3) decreased blood folic acid. The age-related nature of these mechanisms comes from age-associated decreased muscle mass, increased visceral fat and changes in diet. This mechanism also explains why many people do not develop Alzheimer’s disease. Simple changes in lifestyle and diet can prevent Alzheimer’s disease. Alzheimer’s disease is caused by a cascade of events that culminates in damage to the blood–brain barrier and damage to neurons. The blood–brain barrier keeps toxic molecules out of the brain and retains essential molecules in the brain. Lactic acid is a nutrient to the brain and is produced by exercise. Damage to endothelial cells and pericytes by inadequate lactic acid leads to blood–brain barrier damage and brain damage. Inadequate folate intake and oxidative stress induced by activation of transient receptor potential cation channels and endothelial nitric oxide synthase damage the blood–brain barrier. NAD depletion due to inadequate intake of nicotinamide and alterations in the kynurenine pathway damages neurons. Changes in microRNA levels may be the terminal events that cause neuronal death leading to Alzheimer’s disease. A new mechanism of Alzheimer’s disease induction is presented involving lactic acid, ceramide, IL-1β, tumor necrosis factor α, folate, nicotinamide, kynurenine metabolites and microRNA.

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