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1.
J Clin Invest ; 132(12)2022 06 15.
Article in English | MEDLINE | ID: mdl-35536645

ABSTRACT

Caffeine is the most widely consumed psychoactive substance in the world. Strikingly, the molecular pathways engaged by its regular consumption remain unclear. We herein addressed the mechanisms associated with habitual (chronic) caffeine consumption in the mouse hippocampus using untargeted orthogonal omics techniques. Our results revealed that chronic caffeine exerts concerted pleiotropic effects in the hippocampus at the epigenomic, proteomic, and metabolomic levels. Caffeine lowered metabolism-related processes (e.g., at the level of metabolomics and gene expression) in bulk tissue, while it induced neuron-specific epigenetic changes at synaptic transmission/plasticity-related genes and increased experience-driven transcriptional activity. Altogether, these findings suggest that regular caffeine intake improves the signal-to-noise ratio during information encoding, in part through fine-tuning of metabolic genes, while boosting the salience of information processing during learning in neuronal circuits.


Subject(s)
Caffeine , Proteomics , Animals , Caffeine/metabolism , Caffeine/pharmacology , Hippocampus/metabolism , Learning , Mice , Neuronal Plasticity/physiology
2.
Front Mol Neurosci ; 15: 841892, 2022.
Article in English | MEDLINE | ID: mdl-35250480

ABSTRACT

Alzheimer's disease (AD) is the leading cause of dementia. While impaired glucose homeostasis has been shown to increase AD risk and pathological loss of tau function, the latter has been suggested to contribute to the emergence of the glucose homeostasis alterations observed in AD patients. However, the links between tau impairments and glucose homeostasis, remain unclear. In this context, the present study aimed at investigating the metabolic phenotype of a new tau knock-in (KI) mouse model, expressing, at a physiological level, a human tau protein bearing the P301L mutation under the control of the endogenous mouse Mapt promoter. Metabolic investigations revealed that, while under chow diet tau KI mice do not exhibit significant metabolic impairments, male but not female tau KI animals under High-Fat Diet (HFD) exhibited higher insulinemia as well as glucose intolerance as compared to control littermates. Using immunofluorescence, tau protein was found colocalized with insulin in the ß cells of pancreatic islets in both mouse (WT, KI) and human pancreas. Isolated islets from tau KI and tau knock-out mice exhibited impaired glucose-stimulated insulin secretion (GSIS), an effect recapitulated in the mouse pancreatic ß-cell line (MIN6) following tau knock-down. Altogether, our data indicate that loss of tau function in tau KI mice and, particularly, dysfunction of pancreatic ß cells might promote glucose homeostasis impairments and contribute to metabolic changes observed in AD.

3.
Acta Neuropathol ; 141(1): 39-65, 2021 01.
Article in English | MEDLINE | ID: mdl-33079262

ABSTRACT

Several lines of recent evidence indicate that the amyloid precursor protein-derived C-terminal fragments (APP-CTFs) could correspond to an etiological trigger of Alzheimer's disease (AD) pathology. Altered mitochondrial homeostasis is considered an early event in AD development. However, the specific contribution of APP-CTFs to mitochondrial structure, function, and mitophagy defects remains to be established. Here, we demonstrate in neuroblastoma SH-SY5Y cells expressing either APP Swedish mutations, or the ß-secretase-derived APP-CTF fragment (C99) combined with ß- and γ-secretase inhibition, that APP-CTFs accumulation independently of Aß triggers excessive mitochondrial morphology alteration (i.e., size alteration and cristae disorganization) associated with enhanced mitochondrial reactive oxygen species production. APP-CTFs accumulation also elicit basal mitophagy failure illustrated by enhanced conversion of LC3, accumulation of LC3-I and/or LC3-II, non-degradation of SQSTM1/p62, inconsistent Parkin and PINK1 recruitment to mitochondria, enhanced levels of membrane and matrix mitochondrial proteins, and deficient fusion of mitochondria with lysosomes. We confirm the contribution of APP-CTFs accumulation to morphological mitochondria alteration and impaired basal mitophagy in vivo in young 3xTgAD transgenic mice treated with γ-secretase inhibitor as well as in adeno-associated-virus-C99 injected mice. Comparison of aged 2xTgAD and 3xTgAD mice indicates that, besides APP-CTFs, an additional contribution of Aß to late-stage mitophagy activation occurs. Importantly, we report on mitochondrial accumulation of APP-CTFs in human post-mortem sporadic AD brains correlating with mitophagy failure molecular signature. Since defective mitochondria homeostasis plays a pivotal role in AD pathogenesis, targeting mitochondrial dysfunctions and/or mitophagy by counteracting early APP-CTFs accumulation may represent relevant therapeutic interventions in AD.


Subject(s)
Alzheimer Disease/pathology , Amyloid beta-Protein Precursor/genetics , Amyloid beta-Protein Precursor/metabolism , Brain/pathology , Mitochondria/pathology , Mitochondria/ultrastructure , Mitophagy/genetics , Aged , Aged, 80 and over , Alzheimer Disease/metabolism , Amyloid Precursor Protein Secretases/antagonists & inhibitors , Amyloid Precursor Protein Secretases/metabolism , Animals , Aspartic Acid Endopeptidases/antagonists & inhibitors , Aspartic Acid Endopeptidases/metabolism , Autopsy , Cell Line , Female , Humans , Membrane Potential, Mitochondrial , Mice , Mitochondria/metabolism , Peptide Fragments/genetics , Peptide Fragments/metabolism , Reactive Oxygen Species/metabolism
4.
Data Brief ; 31: 105921, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32676526

ABSTRACT

The data presented in this paper are related to the research article "Functional characterization of a FUS mutant zebrafish line as a novel genetic model for ALS". In this model the lack of fus causes reduced lifespan as well as impaired motor abilities associated with a decrease of motor neurons axons lenght and an increase of neuromuscular junctions fragmentation. Data in this article describes the global locomotor activity data at 3, 4 and 5 days post fertilization in WT, fus heterozygous (fus+/-) and fus homozygous (fus-/-) zebrafish embryos as a response to visual light stimulation, with particular attention on the freezing respose.

5.
Neurobiol Dis ; 142: 104935, 2020 08.
Article in English | MEDLINE | ID: mdl-32380281

ABSTRACT

Mutations in Fused in sarcoma (FUS), an RNA-binding protein, are known to cause Amyotrophic Lateral Sclerosis (ALS). However, molecular mechanisms due to loss of FUS function remain unclear and controversial. Here, we report the characterization and phenotypic analysis of a deletion mutant of the unique FUS orthologue in zebrafish where Fus protein levels are depleted. The homozygous mutants displayed a reduced lifespan as well as impaired motor abilities associated with specific cellular deficits, including decreased motor neurons length and neuromuscular junctions (NMJ) fragmentation. Furthermore, we demonstrate that these cellular impairments are linked to the misregulation of mRNA expression of acetylcholine receptor (AChR) subunits and histone deacetylase 4, markers of denervation and reinnervation processes observed in ALS patients. In addition, fus loss of function alters tau transcripts favoring the expression of small tau isoforms. Overall, this new animal model extends our knowledge on FUS and supports the relevance of FUS loss of function in ALS physiopathology.


Subject(s)
Amyotrophic Lateral Sclerosis/genetics , Disease Models, Animal , Models, Genetic , RNA-Binding Protein FUS/genetics , Zebrafish/genetics , Amyotrophic Lateral Sclerosis/pathology , Animals , Behavior, Animal/physiology , Motor Neurons/pathology , Mutation , Neuromuscular Junction/pathology
6.
FASEB J ; 34(2): 2968-2977, 2020 02.
Article in English | MEDLINE | ID: mdl-31908108

ABSTRACT

Tau hyperphosphorylation is a major neuropathological hallmark of many neurodegenerative disorders such as Alzheimer's disease. Several anesthetics have been shown previously to induced marked tau hyperphosphorylation. Although the ketamine/xylazine mixture is one of the most commonly used anesthetic agents in animal research and veterinary practice, the effect of this anesthetic agent on tau phosphorylation still remains to be determined. Here, we found that ketamine-/xylazine-induced a rapid and robust hyperphosphorylation of tau in a dose-dependent manner under normothermic and hypothermic conditions in mice. When used together, ketamine and xylazine exerted a synergistic action on tau phosphorylation most strongly not only on epitopes S396 and S262, but also on other residues (T181, and S202/T205). We observed that activation of the calmodulin-dependent protein kinase II (CaMKII) is the major upstream molecular event leading to tau hyperphosphorylation following ketamine/xylazine anesthesia in mice. Moreover, we observed that intracerebroventricular injection of the selective CaMKII inhibitor KN93 attenuated tau hyperphosphorylation. Since ketamine/xylazine also had a marked impact on other key molecular signaling pathways involving the MAP/microtubule affinity-regulating kinase (MARK), extracellular signal-regulated kinase (ERK), and glycogen synthase kinase-3 (GSK3), our study calls for high caution and careful monitoring when using this anesthetic agent in laboratory animal settings across all fields of biological sciences in order to avoid artifactual results.


Subject(s)
Anesthetics, Dissociative/pharmacology , Calcium-Calmodulin-Dependent Protein Kinase Type 2/metabolism , Ketamine/pharmacology , MAP Kinase Signaling System/drug effects , Xylazine/pharmacology , tau Proteins/metabolism , Anesthetics, Dissociative/adverse effects , Animals , Ketamine/adverse effects , Male , Mice , Phosphorylation/drug effects , Xylazine/adverse effects
7.
Mol Psychiatry ; 25(8): 1876-1900, 2020 08.
Article in English | MEDLINE | ID: mdl-29950682

ABSTRACT

Synaptic dysfunction plays a central role in Alzheimer's disease (AD), since it drives the cognitive decline. An association between a polymorphism of the adenosine A2A receptor (A2AR) encoding gene-ADORA2A, and hippocampal volume in AD patients was recently described. In this study, we explore the synaptic function of A2AR in age-related conditions. We report, for the first time, a significant overexpression of A2AR in hippocampal neurons of aged humans, which is aggravated in AD patients. A similar profile of A2AR overexpression in rats was sufficient to drive age-like memory impairments in young animals and to uncover a hippocampal LTD-to-LTP shift. This was accompanied by increased NMDA receptor gating, dependent on mGluR5 and linked to enhanced Ca2+ influx. We confirmed the same plasticity shift in memory-impaired aged rats and APP/PS1 mice modeling AD, which was rescued upon A2AR blockade. This A2AR/mGluR5/NMDAR interaction might prove a suitable alternative for regulating aberrant mGluR5/NMDAR signaling in AD without disrupting their constitutive activity.


Subject(s)
Aging/metabolism , Long-Term Synaptic Depression , Neurons/metabolism , Receptor, Adenosine A2A/metabolism , Receptor, Metabotropic Glutamate 5/metabolism , Receptors, N-Methyl-D-Aspartate/metabolism , Adenosine/metabolism , Alzheimer Disease/metabolism , Animals , Cells, Cultured , Hippocampus/metabolism , Humans , Mice , Rats , Rats, Sprague-Dawley , Spatial Memory
8.
Neurobiol Dis ; 129: 217-233, 2019 09.
Article in English | MEDLINE | ID: mdl-30928644

ABSTRACT

Alzheimer's Disease is a devastating dementing disease involving amyloid deposits, neurofibrillary tangles, progressive and irreversible cognitive impairment. Today, only symptomatic drugs are available and therapeutic treatments, possibly acting at a multiscale level, are thus urgently needed. To that purpose, we designed multi-effects compounds by synthesizing drug candidates derived by substituting a novel N,N'-disubstituted piperazine anti-amyloid scaffold and adding acetylcholinesterase inhibition property. Two compounds were synthesized and evaluated. The most promising hybrid molecule reduces both the amyloid pathology and the Tau pathology as well as the memory impairments in a preclinical model of Alzheimer's disease. In vitro also, the compound reduces the phosphorylation of Tau and inhibits the release of Aß peptides while preserving the processing of other metabolites of the amyloid precursor protein. We synthetized and tested the first drug capable of ameliorating both the amyloid and Tau pathology in animal models of AD as well as preventing the major brain lesions and associated memory impairments. This work paves the way for future compound medicines against both Alzheimer's-related brain lesions development and the associated cognitive impairments.


Subject(s)
Alzheimer Disease/pathology , Brain/drug effects , Nerve Degeneration/pathology , Neuroprotective Agents/pharmacology , Piperazines/pharmacology , Animals , Cell Line , Disease Models, Animal , Humans , Memory/drug effects , Mice, Inbred C57BL , Mice, Transgenic , Neurons/drug effects , Plaque, Amyloid/pathology
9.
Adv Exp Med Biol ; 1184: 207-216, 2019.
Article in English | MEDLINE | ID: mdl-32096040

ABSTRACT

Myotonic dystrophies (DM) are rare inherited neuromuscular disorders linked to microsatellite unstable expansions in non-coding regions of ubiquitously expressed genes. The DMPK and ZNF9/CNBP genes which mutations are responsible for DM1 and DM2 respectively. DM are multisystemic disorders with brain affection and cognitive deficits. Brain lesions consisting of neurofibrillary tangles are often observed in DM1 and DM2 brain. Neurofibrillary tangles (NFT) made of aggregates of hyper and abnormally phosphorylated isoforms of Tau proteins are neuropathological lesions common to more than 20 neurological disorders globally referred to as Tauopathies. Although NFT are observed in DM1 and DM2 brain, the question of whether DM1 and DM2 are Tauopathies remains a matter of debate. In the present review, several pathophysiological processes including, missplicing, nucleocytoplasmic transport disruption, RAN translation which are common mechanisms implicated in neurodegenerative diseases will be described. Together, these processes including the missplicing of Tau are providing evidence that DM1 and DM2 are not solely muscular diseases but that their brain affection component share many similarities with Tauopathies and other neurodegenerative diseases. Understanding DM1 and DM2 pathophysiology is therefore valuable to more globally understand other neurodegenerative diseases such as Tauopathies but also frontotemporal lobar neurodegeneration and amyotrophic lateral sclerosis.


Subject(s)
Gain of Function Mutation , Myotonic Dystrophy/genetics , Myotonic Dystrophy/metabolism , RNA/metabolism , Tauopathies/genetics , Tauopathies/metabolism , Humans , Protein Isoforms/chemistry , Protein Isoforms/genetics , Protein Isoforms/metabolism , tau Proteins/chemistry , tau Proteins/genetics , tau Proteins/metabolism
10.
PLoS Curr ; 102018 Jul 09.
Article in English | MEDLINE | ID: mdl-30050723

ABSTRACT

Emergency medical teams provide urgent medical and surgical care in emergencies characterized by a surge in trauma or disease. Rehabilitation has historically not been included in the acute phase of care, as teams have either not perceived it as their responsibility or have relied on external providers, including local services and international organizations, to provide services. Low- and middle-income countries, which often have limited rehabilitation capacity within their health system,  are particularly vulnerable to disaster and are usually  ill-equipped to address the increased burden of rehabilitation needs that arise. The resulting unmet needs for rehabilitation culminate in unnecessary complications for patients, delayed recovery, reduced functional outcomes, and often impede return to daily activities and life roles. Recognizing the systemic neglect of rehabilitation in global emergency medical response, the World Health Organization, in collaboration with key operational partners and experts, developed technical standards and recommendations for rehabilitation which are integrated into  the WHO verification  process for EMTs. This protocol report presents: 1) the rationale for the development of the standards and accompanying recommendations; 2) the methodology of the development process; 3) the minimum standards and other significant content included in the document; 4) challenges encountered during development and implementation; and 5) current and next steps to continue strengthening the inclusion of rehabilitation in emergency medical response.

11.
Methods Mol Biol ; 1523: 251-261, 2017.
Article in English | MEDLINE | ID: mdl-27975254

ABSTRACT

Technology breakthrough in proteomics enables to gather qualitative and quantitative information about a protein or a complex mixture of proteins. Two-dimensional gel electrophoresis remains an interesting technique, which provides an overview of the complexity of isovariants from a single protein when coupled to western blotting. Here, we describe a detailed protocol for the two-dimensional analysis of microtubule-associated Tau isovariants from cell to human or mouse brain tissue. We provide protocol enabling to separate native and Tau proteins that are aggregated in neurodegenerative disorders such as Alzheimer's disease.


Subject(s)
Electrophoresis, Gel, Two-Dimensional/methods , Microtubule-Associated Proteins/metabolism , tau Proteins/metabolism , Alzheimer Disease/metabolism , Animals , Brain/metabolism , Humans , Isoelectric Focusing , Mice , Microtubule-Associated Proteins/chemistry , Protein Processing, Post-Translational , tau Proteins/chemistry
12.
Mov Disord ; 31(12): 1883-1890, 2016 12.
Article in English | MEDLINE | ID: mdl-27709663

ABSTRACT

BACKGROUND: Progressive supranuclear palsy (PSP) is a rare neurodegenerative disease causing parkinsonian symptoms. Altered DNA methylation of the microtubule-associated protein tau gene correlates with the expression changes in Alzheimer's disease and Parkinson's disease brains. However, few studies examine the sequences beyond the constitutive promoter. OBJECTIVES: Because activating different microtubule-associated protein tau gene control regions via methylation might regulate the differential tau expression constituting the specific signatures of individual tauopathies, we compared methylation of a candidate promoter, intron 0. METHODS: We assessed DNA methylation in the brains of patients with different tauopathies (35 Alzheimer's disease, 10 corticobasal degeneration, and 18 PSP) and 19 controls by intron 0 pyrosequencing. We also evaluated methylation in an independent cohort of 11 PSP cases and 12 controls. Frontal (affected by tau pathology) and occipital (unaffected) cortices were analyzed. RESULTS: In the initial samples, one CpG island site in intron 0 (CpG1) showed significant hypomethylation in PSP-affected frontal cortices when compared with controls (P = .022). Such hypomethylation was observed in replicate samples, but not in occipital cortices or other tauopathies. PSP and control samples (combining the initial and replicate samples) remained significantly different after adjustment for potential confounding factors (age, H1/H1 diplotype; P = .0005). PSP-affected tissues exhibited microtubule-associated protein tau RNA hyperexpression when compared with controls (P = .004), although no correlation with CpG1 methylation was observed. CONCLUSIONS: This exploratory study suggests that regions other than the constitutive promoter may be involved in microtubule-associated protein tau gene regulation in tauopathies and that intron 0 hypomethylation may be a specific epigenetic signature of PSP. These preliminary findings require confirmation. © 2016 International Parkinson and Movement Disorder Society.


Subject(s)
Frontal Lobe/metabolism , Occipital Lobe/metabolism , Supranuclear Palsy, Progressive/metabolism , Tissue Banks , tau Proteins/metabolism , Aged , Aged, 80 and over , Alzheimer Disease/metabolism , CpG Islands , DNA Methylation , Female , Humans , Introns , Male , Middle Aged , Promoter Regions, Genetic
13.
Acta Neuropathol Commun ; 4(1): 74, 2016 07 19.
Article in English | MEDLINE | ID: mdl-27435172

ABSTRACT

Reduction of Tau protein expression was described in 2003 by Zhukareva et al. in a variant of frontotemporal lobar degeneration (FTLD) referred to as diagnosis of dementia lacking distinctive histopathology, then re-classified as FTLD with ubiquitin inclusions. However, the analysis of Tau expression in FTLD has not been reconsidered since then. Knowledge of the molecular basis of protein aggregates and genes that are mutated in the FTLD spectrum would enable to determine whether the "Tau-less" is a separate pathological entity or if it belongs to an existing subclass of FTLD. To address this question, we have analyzed Tau expression in the frontal brain areas from control, Alzheimer's disease and FTLD cases, including FTLD- Tau (MAPT), FTLD-TDP (sporadic, FTLD-TDP-GRN, FTLD-TDP-C9ORF72) and sporadic FTLD-FUS, using western blot and 2D-DIGE (Two-Dimensional fluorescence Difference Gel Electrophoresis) approaches. Surprisingly, we found that most of the FTLD-TDP-GRN brains are characterized by a huge reduction of Tau protein expression without any decrease in Tau mRNA levels. Interestingly, only cases affected by point mutations, rather than cases with total deletion of one GRN allele, seem to be affected by this reduction of Tau protein expression. Moreover, proteomic analysis highlighted correlations between reduced Tau protein level, synaptic impairment and massive reactive astrogliosis in these FTLD-GRN cases. Consistent with a recent study, our data also bring new insights regarding the role of progranulin in neurodegeneration by suggesting its involvement in lysosome and synaptic regulation. Together, our results demonstrate a strong association between progranulin deficiency and reduction of Tau protein expression that could lead to severe neuronal and glial dysfunctions. Our study also indicates that this FTLD-TDP-GRN subgroup could be part as a distinct entity of FTLD classification.


Subject(s)
Frontal Lobe/metabolism , Frontotemporal Lobar Degeneration/genetics , Frontotemporal Lobar Degeneration/metabolism , Intercellular Signaling Peptides and Proteins/genetics , tau Proteins/metabolism , Adult , Aged , Aged, 80 and over , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Astrocytes/metabolism , Astrocytes/pathology , Female , Frontal Lobe/pathology , Frontotemporal Lobar Degeneration/classification , Frontotemporal Lobar Degeneration/pathology , Gene Expression , Gliosis/genetics , Gliosis/metabolism , Gliosis/pathology , Humans , Intercellular Signaling Peptides and Proteins/deficiency , Male , Middle Aged , Point Mutation , Progranulins , Proteome , RNA, Messenger/metabolism , Sequence Deletion
14.
Neurology ; 85(15): 1293-300, 2015 Oct 13.
Article in English | MEDLINE | ID: mdl-26354981

ABSTRACT

OBJECTIVE: To describe a cluster of progressive supranuclear palsy (PSP) in northern France. PSP has not been reported in geographical, temporal, or occupational clusters. A unit of Neurology and Neurogeriatrics opened in 2005 at the Centre Hospitalier de Wattrelos, serving the population of Wattrelos and Leers (combined population 51,551) and parts of neighboring towns. For most of the 20th century, this area was a center for chromate and phosphate ore processing, textile dyeing, and tanning. Significant industrial waste persists close to residential areas. METHODS: From 2005 to 2014, 92 patients with PSP at Centre Hospitalier de Wattrelos were identified and studied. Detailed residential data were available in the medical records. Eighty cases have had magnetic resonance head scanning and 60 have died, of whom 13 have been examined neuropathologically. RESULTS: The ratio of observed to expected PSP incidence over the period 2005 to 2012 was 12.3 (95% confidence interval: 7.4-35.9). Mean onset age was 74.3 years. The Richardson syndrome/PSP-parkinsonism ratio was 43%/42%. Four other phenotypes each occurred in 2% to 5%. Onset was gait/balance difficulty in 52%. None of the 92 affected patients were relatives and 7 were of North African ancestry. MRI was compatible with a clinical diagnostic of PSP in all cases. Histopathologic examination confirmed neurofibrillary degeneration and tufted astrocytes in all autopsied cases. Western blots revealed a typical tau 4R doublet. The tau H1 haplotype occurred in 95.8% of cases' chromosomes. CONCLUSIONS: We have identified a cluster of PSP in a geographical area with severe environmental contamination by industrial metals.


Subject(s)
Haplotypes/genetics , Movement Disorders/epidemiology , Supranuclear Palsy, Progressive/diagnosis , Supranuclear Palsy, Progressive/epidemiology , Aged , Aged, 80 and over , Female , France , Humans , Magnetic Resonance Imaging/methods , Male , Middle Aged , Movement Disorders/diagnosis , Movement Disorders/genetics , Phenotype , Supranuclear Palsy, Progressive/complications , tau Proteins/genetics , tau Proteins/metabolism
15.
Sci Rep ; 5: 9659, 2015 May 14.
Article in English | MEDLINE | ID: mdl-25974414

ABSTRACT

Tau is a central player in Alzheimer's disease (AD) and related Tauopathies, where it is found as aggregates in degenerating neurons. Abnormal post-translational modifications, such as truncation, are likely involved in the pathological process. A major step forward in understanding the role of Tau truncation would be to identify the precise cleavage sites of the several truncated Tau fragments that are observed until now in AD brains, especially those truncated at the N-terminus, which are less characterized than those truncated at the C-terminus. Here, we optimized a proteomics approach and succeeded in identifying a number of new N-terminally truncated Tau species from the human brain. We initiated cell-based functional studies by analyzing the biochemical characteristics of two N-terminally truncated Tau species starting at residues Met11 and Gln124 respectively. Our results show, interestingly, that the Gln124-Tau fragment displays a stronger ability to bind and stabilize microtubules, suggesting that the Tau N-terminal domain could play a direct role in the regulation of microtubule stabilization. Future studies based on our new N-terminally truncated-Tau species should improve our knowledge of the role of truncation in Tau biology as well as in the AD pathological process.


Subject(s)
Alzheimer Disease/pathology , Microtubules/physiology , Tubulin/metabolism , tau Proteins/genetics , Acetylation , Alzheimer Disease/genetics , Brain/pathology , Cell Line , Humans , Nerve Degeneration/metabolism , Phosphorylation , Protein Binding/genetics , Protein Processing, Post-Translational , Proteomics , tau Proteins/metabolism
16.
Neurobiol Aging ; 36(2): 730-9, 2015 Feb.
Article in English | MEDLINE | ID: mdl-25443285

ABSTRACT

Cognitive decline, the hallmark of Alzheimer's disease, and accompanying neuropsychiatric symptoms share dysfunctions of synaptic processes as a common cellular pathomechanism. Long-term potentiation has proven to be a sensitive tool for the "diagnosis" of such synaptic dysfunctions. Much less, however, is known about how long-term depression (LTD), an alternative mechanism for the storage of memory, is affected by Alzheimer's disease progression. Here, we demonstrate that impaired late LTD (>3 hours) in THY-Tau22 mice can be rescued by either inhibition of glycogen synthase kinase-3 (GSK3ß) activity or by application of the protein-phosphatase 2A agonist selenate. In line with these findings, we observed increased phosphorylation of GSK3ß at Y216 and reduced total phosphatase activity in biochemical assays of hippocampal tissue of THY-Tau22 mice. Interestingly, LTD induction and pharmacologic inhibition of GSK3ß appeared to downregulate GSK3ß activity via a marked upregulation of phosphorylation at the inhibitory Ser9 residue. Our results point to alterations in phosphorylation and/or dephosphorylation homeostasis as key mechanisms underlying the deficits in LTD and hippocampus-dependent learning found in THY-Tau22 mice.


Subject(s)
Depression/genetics , tau Proteins/genetics , Alzheimer Disease/psychology , Animals , Depression/diagnosis , Depression/drug therapy , Depression/psychology , Disease Models, Animal , Glycogen Synthase Kinase 3/antagonists & inhibitors , Hippocampus/metabolism , Hippocampus/physiology , Learning , Long-Term Potentiation , Male , Memory , Mice, Transgenic , Molecular Targeted Therapy , Phosphorylation , Protein Phosphatase 2/metabolism
17.
J Biol Chem ; 290(7): 4059-74, 2015 Feb 13.
Article in English | MEDLINE | ID: mdl-25540200

ABSTRACT

A link between Tau phosphorylation and aggregation has been shown in different models for Alzheimer disease, including yeast. We used human Tau purified from yeast models to generate new monoclonal antibodies, of which three were further characterized. The first antibody, ADx201, binds the Tau proline-rich region independently of the phosphorylation status, whereas the second, ADx215, detects an epitope formed by the Tau N terminus when Tau is not phosphorylated at Tyr(18). For the third antibody, ADx210, the binding site could not be determined because its epitope is probably conformational. All three antibodies stained tangle-like structures in different brain sections of THY-Tau22 transgenic mice and Alzheimer patients, and ADx201 and ADx210 also detected neuritic plaques in the cortex of the patient brains. In hippocampal homogenates from THY-Tau22 mice and cortex homogenates obtained from Alzheimer patients, ADx215 consistently stained specific low order Tau oligomers in diseased brain, which in size correspond to Tau dimers. ADx201 and ADx210 additionally reacted to higher order Tau oligomers and presumed prefibrillar structures in the patient samples. Our data further suggest that formation of the low order Tau oligomers marks an early disease stage that is initiated by Tau phosphorylation at N-terminal sites. Formation of higher order oligomers appears to require additional phosphorylation in the C terminus of Tau. When used to assess Tau levels in human cerebrospinal fluid, the antibodies permitted us to discriminate patients with Alzheimer disease or other dementia like vascular dementia, indicative that these antibodies hold promising diagnostic potential.


Subject(s)
Alzheimer Disease/diagnosis , Antibodies, Monoclonal , Brain/pathology , Hippocampus/pathology , tau Proteins/chemistry , tau Proteins/immunology , Alzheimer Disease/cerebrospinal fluid , Alzheimer Disease/immunology , Animals , Biotinylation , Blotting, Western , Brain/immunology , Brain/metabolism , Disease Progression , Enzyme-Linked Immunosorbent Assay , Epitope Mapping , Hippocampus/immunology , Hippocampus/metabolism , Humans , Immunization , Immunoenzyme Techniques , Immunoprecipitation , Magnetic Resonance Spectroscopy , Membrane Microdomains , Mice , Mice, Inbred BALB C , Mice, Transgenic , Neurofibrillary Tangles , Peptide Fragments/metabolism , Phosphorylation , Plaque, Amyloid , Saccharomyces cerevisiae , tau Proteins/cerebrospinal fluid
18.
Cereb Cortex ; 25(9): 3107-21, 2015 Sep.
Article in English | MEDLINE | ID: mdl-24860020

ABSTRACT

Brain-derived neurotrophic factor (BDNF) and its high-affinity full-length (FL) receptor, TrkB-FL, play a central role in the nervous system by providing trophic support to neurons and regulating synaptic plasticity and memory. TrkB and BDNF signaling are impaired in Alzheimer's disease (AD), a neurodegenerative disease involving accumulation of amyloid-ß (Aß) peptide. We recently showed that Aß leads to a decrease of TrkB-FL receptor and to an increase of truncated TrkB receptors by an unknown mechanism. In the present study, we found that (1) Aß selectively increases mRNA levels for the truncated TrkB isoforms without affecting TrkB-FL mRNA levels, (2) Aß induces a calpain-mediated cleavage on TrkB-FL receptors, downstream of Shc-binding site, originating a new truncated TrkB receptor (TrkB-T') and an intracellular fragment (TrkB-ICD), which is also detected in postmortem human brain samples, (3) Aß impairs BDNF function in a calpain-dependent way, as assessed by the inability of BDNF to modulate neurotransmitter (GABA and glutamate) release from hippocampal nerve terminals, and long-term potentiation in hippocampal slices. It is concluded that Aß-induced calpain activation leads to TrkB cleavage and impairment of BDNF neuromodulatory actions.


Subject(s)
Amyloid beta-Peptides/metabolism , Brain-Derived Neurotrophic Factor/metabolism , Calpain/pharmacology , Frontal Lobe/drug effects , Neurons/drug effects , Receptor, trkB/metabolism , Animals , Brain/cytology , Embryo, Mammalian , Enzyme Inhibitors/pharmacology , Female , Gene Expression Regulation/drug effects , Glutamic Acid/metabolism , Humans , Long-Term Potentiation/drug effects , Long-Term Potentiation/physiology , Male , Pregnancy , Rats , Rats, Sprague-Dawley , Rats, Wistar , Receptor, trkB/genetics , Synaptosomes/drug effects , Synaptosomes/metabolism , gamma-Aminobutyric Acid/metabolism
19.
J Vis Exp ; (86)2014 Apr 10.
Article in English | MEDLINE | ID: mdl-24747743

ABSTRACT

Two-dimensional gel electrophoresis (2DE) is a powerful tool to uncover proteome modifications potentially related to different physiological or pathological conditions. Basically, this technique is based on the separation of proteins according to their isoelectric point in a first step, and secondly according to their molecular weights by SDS polyacrylamide gel electrophoresis (SDS-PAGE). In this report an optimized sample preparation protocol for little amount of human post-mortem and mouse brain tissue is described. This method enables to perform both two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) and mini 2DE immunoblotting. The combination of these approaches allows one to not only find new proteins and/or protein modifications in their expression thanks to its compatibility with mass spectrometry detection, but also a new insight into markers validation. Thus, mini-2DE coupled to western blotting permits to identify and validate post-translational modifications, proteins catabolism and provides a qualitative comparison among different conditions and/or treatments. Herein, we provide a method to study components of protein aggregates found in AD and Lewy body dementia such as the amyloid-beta peptide and the alpha-synuclein. Our method can thus be adapted for the analysis of the proteome and insoluble proteins extract from human brain tissue and mice models too. In parallel, it may provide useful information for the study of molecular and cellular pathways involved in neurodegenerative diseases as well as potential novel biomarkers and therapeutic targets.


Subject(s)
Brain/metabolism , Immunoblotting/methods , Nerve Tissue Proteins/analysis , Proteome/analysis , Two-Dimensional Difference Gel Electrophoresis/methods , Animals , Brain Chemistry , Carbocyanines/chemistry , Fluorescent Dyes/chemistry , Humans , Mice , Nerve Tissue Proteins/metabolism , Proteome/metabolism
20.
J Alzheimers Dis ; 37(4): 769-76, 2013.
Article in English | MEDLINE | ID: mdl-23948919

ABSTRACT

Frontotemporal lobe degeneration includes a large spectrum of neurodegenerative disorders. Patients with frontotemporal dementia with parkinsonism linked to chromosome 17 exhibit heterogeneity in both clinical and neuropathological features. Here, we report the case of a young patient with a G389R mutation. This teenager girl was 17 years old when she progressively developed severe behavioral disturbances. First, she was considered to be suffering from atypical depression. After 2 years, she was referred to the department of neurology. By this time, the patient exhibited typical frontotemporal dementia with mild extrapyramidal disorders. The main behavioral features included apathy and reduced speech output. MRI and SPECT showed a frontotemporal atrophy and hypofixation, respectively. She died 7 years after onset. Three relatives on her father side had also died after early onset dementia. Genetic testing revealed a heterozygous guanine to cytosine mutation at the first base of codon 389 (Exon 13) of MAPT, the tau gene, resulting in a glycine to arginine substitution, in the patient and her non-affected father. Postmortem neuropathological and biochemical data indicate a Pick-like tau pathology but with phosphoserine 262-positive immunoreactivity. This case is remarkable because of the extremely early onset of the disease.


Subject(s)
Frontotemporal Dementia/diagnosis , Frontotemporal Dementia/genetics , Mutation/genetics , Parkinsonian Disorders/diagnosis , Parkinsonian Disorders/genetics , tau Proteins/genetics , Adolescent , Age Factors , Codon/genetics , Early Diagnosis , Fatal Outcome , Female , Frontotemporal Dementia/complications , Humans , Longitudinal Studies , Male , Parkinsonian Disorders/complications , Pedigree
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