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1.
Nat Methods ; 21(7): 1349-1363, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38849569

ABSTRACT

The Long-read RNA-Seq Genome Annotation Assessment Project Consortium was formed to evaluate the effectiveness of long-read approaches for transcriptome analysis. Using different protocols and sequencing platforms, the consortium generated over 427 million long-read sequences from complementary DNA and direct RNA datasets, encompassing human, mouse and manatee species. Developers utilized these data to address challenges in transcript isoform detection, quantification and de novo transcript detection. The study revealed that libraries with longer, more accurate sequences produce more accurate transcripts than those with increased read depth, whereas greater read depth improved quantification accuracy. In well-annotated genomes, tools based on reference sequences demonstrated the best performance. Incorporating additional orthogonal data and replicate samples is advised when aiming to detect rare and novel transcripts or using reference-free approaches. This collaborative study offers a benchmark for current practices and provides direction for future method development in transcriptome analysis.


Subject(s)
Gene Expression Profiling , RNA-Seq , Humans , Animals , Mice , RNA-Seq/methods , Gene Expression Profiling/methods , Transcriptome , Sequence Analysis, RNA/methods , Molecular Sequence Annotation/methods
2.
Nucleic Acids Res ; 51(D1): D942-D949, 2023 01 06.
Article in English | MEDLINE | ID: mdl-36420896

ABSTRACT

GENCODE produces high quality gene and transcript annotation for the human and mouse genomes. All GENCODE annotation is supported by experimental data and serves as a reference for genome biology and clinical genomics. The GENCODE consortium generates targeted experimental data, develops bioinformatic tools and carries out analyses that, along with externally produced data and methods, support the identification and annotation of transcript structures and the determination of their function. Here, we present an update on the annotation of human and mouse genes, including developments in the tools, data, analyses and major collaborations which underpin this progress. For example, we report the creation of a set of non-canonical ORFs identified in GENCODE transcripts, the LRGASP collaboration to assess the use of long transcriptomic data to build transcript models, the progress in collaborations with RefSeq and UniProt to increase convergence in the annotation of human and mouse protein-coding genes, the propagation of GENCODE across the human pan-genome and the development of new tools to support annotation of regulatory features by GENCODE. Our annotation is accessible via Ensembl, the UCSC Genome Browser and https://www.gencodegenes.org.


Subject(s)
Computational Biology , Genome, Human , Humans , Animals , Mice , Molecular Sequence Annotation , Computational Biology/methods , Genome, Human/genetics , Transcriptome/genetics , Gene Expression Profiling , Databases, Genetic
3.
Nat Rev Genet ; 19(9): 535-548, 2018 09.
Article in English | MEDLINE | ID: mdl-29795125

ABSTRACT

Gene maps, or annotations, enable us to navigate the functional landscape of our genome. They are a resource upon which virtually all studies depend, from single-gene to genome-wide scales and from basic molecular biology to medical genetics. Yet present-day annotations suffer from trade-offs between quality and size, with serious but often unappreciated consequences for downstream studies. This is particularly true for long non-coding RNAs (lncRNAs), which are poorly characterized compared to protein-coding genes. Long-read sequencing technologies promise to improve current annotations, paving the way towards a complete annotation of lncRNAs expressed throughout a human lifetime.


Subject(s)
Chromosome Mapping , Gene Expression Profiling , Genome, Human , RNA, Long Noncoding , Transcriptome/physiology , Genome-Wide Association Study , Humans , RNA, Long Noncoding/biosynthesis , RNA, Long Noncoding/genetics
4.
Alzheimers Dement ; 20(10): 6922-6934, 2024 Oct.
Article in English | MEDLINE | ID: mdl-39193664

ABSTRACT

INTRODUCTION: Typical Alzheimer's disease (AD) and limbic-predominant age-related TAR DNA-binding protein 43 (TDP-43) encephalopathy (LATE) are two neurodegenerative diseases that present with a similar initial amnestic clinical phenotype but are associated with distinct proteinopathies. METHODS: We investigated white matter (WM) fiber bundle alterations, using fixel-based analysis, a state-of-the-art diffusion magnetic resonance imaging model, in early AD, presumed LATE, and controls. We also investigated regional cortical atrophy. RESULTS: Both amnestic AD and presumed LATE patients exhibited WM alterations in tracts of the temporal and limbic lobes and in callosal fibers connecting superior frontal gyri. In addition, presumed LATE patients showed alterations in callosal fibers connecting the middle frontal gyri and in the cerebello-thalamo-cortical tract. Cortical thickness was reduced in regions connected by the most altered tracts. DISCUSSION: These findings, the first to describe WM fiber bundle alterations in presumed LATE, are consistent with results on cortical atrophy and with the staging system of tau or TDP-43 accumulation. HIGHLIGHTS: Fixel-based analysis revealed white matter (WM) fiber bundle alterations in presumed limbic-predominant age-related TAR DNA-binding protein 43 encephalopathy (LATE) patients identified by isolated episodic/limbic amnesia, the absence of positive Alzheimer's disease (AD) biomarkers, and no other neurological diagnosis after 2 years of follow-up. Presumed LATE and amnestic AD shared similar patterns of WM alterations in fiber bundles of the limbic and temporal lobes, in congruence with their similar limbic cognitive phenotype. Presumed LATE differed from AD by the alteration of the callosal fibers connecting the middle frontal gyri and of the cerebello-thalamo-cortical tract. WM fiber bundle alterations were consistent with results on regional cortical atrophy. The different anatomical patterns of WM degeneration could provide information on the propagation pathways of distinct proteinopathies.


Subject(s)
Alzheimer Disease , Atrophy , White Matter , Humans , Alzheimer Disease/pathology , Male , Female , Aged , White Matter/pathology , White Matter/diagnostic imaging , Atrophy/pathology , Amnesia/pathology , Diffusion Magnetic Resonance Imaging , Brain/pathology , Brain/diagnostic imaging , Middle Aged , Aged, 80 and over
5.
Nucleic Acids Res ; 49(D1): D916-D923, 2021 01 08.
Article in English | MEDLINE | ID: mdl-33270111

ABSTRACT

The GENCODE project annotates human and mouse genes and transcripts supported by experimental data with high accuracy, providing a foundational resource that supports genome biology and clinical genomics. GENCODE annotation processes make use of primary data and bioinformatic tools and analysis generated both within the consortium and externally to support the creation of transcript structures and the determination of their function. Here, we present improvements to our annotation infrastructure, bioinformatics tools, and analysis, and the advances they support in the annotation of the human and mouse genomes including: the completion of first pass manual annotation for the mouse reference genome; targeted improvements to the annotation of genes associated with SARS-CoV-2 infection; collaborative projects to achieve convergence across reference annotation databases for the annotation of human and mouse protein-coding genes; and the first GENCODE manually supervised automated annotation of lncRNAs. Our annotation is accessible via Ensembl, the UCSC Genome Browser and https://www.gencodegenes.org.


Subject(s)
COVID-19/prevention & control , Computational Biology/methods , Databases, Genetic , Genomics/methods , Molecular Sequence Annotation/methods , SARS-CoV-2/genetics , Animals , COVID-19/epidemiology , COVID-19/virology , Epidemics , Humans , Internet , Mice , Pseudogenes/genetics , RNA, Long Noncoding/genetics , SARS-CoV-2/metabolism , SARS-CoV-2/physiology , Transcription, Genetic/genetics
6.
J Neurol Neurosurg Psychiatry ; 93(5): 459-467, 2022 05.
Article in English | MEDLINE | ID: mdl-35228270

ABSTRACT

OBJECTIVES: To explore whether regional tau binding measured at baseline is associated with the rapidity of Alzheimer's disease (AD) progression over 2 years, as assessed by the decline in specified cognitive domains, and the progression of regional brain atrophy, in comparison with amyloid-positron emission tomography (PET), MRI and cerebrospinal fluid (CSF) biomarkers. METHODS: Thirty-six patients with AD (positive CSF biomarkers and amyloid-PET) and 15 controls underwent a complete neuropsychological assessment, 3T brain MRI, [11C]-PiB and [18F]-flortaucipir PET imaging, and were monitored annually over 2 years, with a second brain MRI after 2 years. We used mixed effects models to explore the relations between tau-PET, amyloid-PET, CSF biomarkers and MRI at baseline and cognitive decline and the progression of brain atrophy over 2 years in patients with AD. RESULTS: Baseline tau-PET was strongly associated with the subsequent cognitive decline in regions that are usually associated with each cognitive domain. No significant relationship was observed between the cognitive decline and initial amyloid load, regional cortical atrophy or CSF biomarkers. Baseline tau tracer binding in the superior temporal gyrus was associated with subsequent atrophy in an inferomedial temporal volume of interest, as was the voxelwise tau tracer binding with subsequent cortical atrophy in the superior temporal, parietal and frontal association cortices. CONCLUSIONS: These results suggest that tau tracer binding is predictive of cognitive decline in AD in domain-specific brain areas, which provides important insights into the interaction between tau burden and neurodegeneration, and is of the utmost importance to develop new prognostic markers that will help improve the design of therapeutic trials.


Subject(s)
Alzheimer Disease , Cognitive Dysfunction , Alzheimer Disease/cerebrospinal fluid , Amyloid beta-Peptides/metabolism , Atrophy , Biomarkers/cerebrospinal fluid , Brain/diagnostic imaging , Brain/metabolism , Cognitive Dysfunction/cerebrospinal fluid , Humans , Positron-Emission Tomography/methods , tau Proteins/metabolism
7.
Acta Neuropathol ; 142(2): 259-278, 2021 08.
Article in English | MEDLINE | ID: mdl-34095977

ABSTRACT

Microduplications of the 17q21.31 chromosomal region encompassing the MAPT gene, which encodes the Tau protein, were identified in patients with a progressive disorder initially characterized by severe memory impairment with or without behavioral changes that can clinically mimic Alzheimer disease. The unique neuropathological report showed a primary tauopathy, which could not be unanimously classified in a given known subtype, showing both 4R- and 3R-tau inclusions, mainly within temporal cortical subregions and basal ganglia, without amyloid deposits. Recently, two subjects harboring the same duplication were reported with an atypical extrapyramidal syndrome and gait disorder. To decipher the phenotypic spectrum associated with MAPT duplications, we studied ten carriers from nine families, including two novel unrelated probands, gathering clinical (n = 10), cerebrospinal fluid (n = 6), MRI (n = 8), dopamine transporter scan (n = 4), functional (n = 5), amyloid (n = 3) and Tau-tracer (n = 2) PET imaging data as well as neuropathological examination (n = 4). Ages at onset ranged from 37 to 57 years, with prominent episodic memory impairment in 8/10 patients, associated with behavioral changes in four, while two patients showed atypical extrapyramidal syndrome with gait disorder at presentation, including one with associated cognitive deficits. Amyloid imaging was negative but Tau imaging showed significant deposits mainly in both mesiotemporal cortex. Dopaminergic denervation was found in 4/4 patients, including three without extrapyramidal symptoms. Neuropathological examination exclusively showed Tau-immunoreactive lesions. Distribution, aspect and 4R/3R tau aggregates composition suggested a spectrum from predominantly 3R, mainly cortical deposits well correlating with cognitive and behavioral changes, to predominantly 4R deposits, mainly in the basal ganglia and midbrain, in patients with prominent extrapyramidal syndrome. Finally, we performed in vitro seeding experiments in HEK-biosensor cells. Morphological features of aggregates induced by homogenates of three MAPT duplication carriers showed dense/granular ratios graduating between those induced by homogenates of a Pick disease and a progressive supranuclear palsy cases. These results suggest that MAPT duplication causes a primary tauopathy associated with diverse clinical and neuropathological features.


Subject(s)
Brain/pathology , Tauopathies/pathology , tau Proteins/metabolism , Adult , Age of Onset , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Cognitive Dysfunction/metabolism , Cognitive Dysfunction/pathology , Female , Heterozygote , Humans , Inclusion Bodies/pathology , Male , Middle Aged , Tauopathies/metabolism , tau Proteins/genetics
8.
Nucleic Acids Res ; 47(D1): D766-D773, 2019 01 08.
Article in English | MEDLINE | ID: mdl-30357393

ABSTRACT

The accurate identification and description of the genes in the human and mouse genomes is a fundamental requirement for high quality analysis of data informing both genome biology and clinical genomics. Over the last 15 years, the GENCODE consortium has been producing reference quality gene annotations to provide this foundational resource. The GENCODE consortium includes both experimental and computational biology groups who work together to improve and extend the GENCODE gene annotation. Specifically, we generate primary data, create bioinformatics tools and provide analysis to support the work of expert manual gene annotators and automated gene annotation pipelines. In addition, manual and computational annotation workflows use any and all publicly available data and analysis, along with the research literature to identify and characterise gene loci to the highest standard. GENCODE gene annotations are accessible via the Ensembl and UCSC Genome Browsers, the Ensembl FTP site, Ensembl Biomart, Ensembl Perl and REST APIs as well as https://www.gencodegenes.org.


Subject(s)
Databases, Genetic , Genome, Human/genetics , Genomics , Pseudogenes/genetics , Animals , Computational Biology , Humans , Internet , Mice , Molecular Sequence Annotation , Software
9.
Psychol Res ; 85(2): 879-886, 2021 Mar.
Article in English | MEDLINE | ID: mdl-31792611

ABSTRACT

Information coming from multiple senses, as compared to a single one, typically enhances our performance. The multisensory improvement has been extensively examined in perception studies, as well as in tasks involving a motor response like a simple reaction time. However, how this effect extends to more complex behavior, typically involving the coordination of movements, such as bimanual coordination or walking, is still unclear. A critical element in achieving motor coordination in complex behavior is its stability. Reaching a stable state in the coordination pattern allows to sustain complex behavior over time (e.g., without interruption or negative consequences, like falling). This study focuses on the relation between stability in the coordination of movement patterns, like walking, and multisensory improvement. Participants walk with unimodal and audio-tactile metronomes presented either at their preferred rate or at a slower walking rate, the instruction being to synchronize their steps to the metronomes. Walking at a slower rate makes gait more variable than walking at the preferred rate. Interestingly however, the multimodal stimuli enhance the stability of motor coordination but only in the slower condition. Thus, the reduced stability of the coordination pattern (at a slower gait rate) prompts the sensorimotor system to capitalize on multimodal stimulation. These findings provide evidence of a new link between multisensory improvement and behavioral stability, in the context of ecological sensorimotor task.


Subject(s)
Gait/physiology , Movement/physiology , Psychomotor Performance/physiology , Walking/physiology , Adult , Female , Humans , Male , Reaction Time/physiology , Touch/physiology
10.
Alzheimers Dement ; 17(11): 1843-1854, 2021 11.
Article in English | MEDLINE | ID: mdl-34855281

ABSTRACT

The pathophysiological processes underlying the development and progression of Alzheimer's disease (AD) on the neuronal level are still unclear. Previous research has hinted at metabolic energy deficits and altered sodium homeostasis with impaired neuronal function as a potential metabolic marker relevant for neurotransmission in AD. Using sodium (23 Na) magnetic resonance (MR) imaging on an ultra-high-field 7 Tesla MR scanner, we found increased cerebral tissue sodium concentration (TSC) in 17 biomarker-defined AD patients compared to 22 age-matched control subjects in vivo. TSC was highly discriminative between controls and early AD stages and was predictive for cognitive state, and associated with regional tau load assessed with flortaucipir-positron emission tomography as a possible mediator of TSC-associated neurodegeneration. TSC could therefore serve as a non-invasive, stage-dependent, metabolic imaging marker. Setting a focus on cellular metabolism and potentially disturbed interneuronal communication due to energy-dependent altered cell homeostasis could hamper progressive cognitive decline by targeting these processes in future interventions.


Subject(s)
Alzheimer Disease , Positron-Emission Tomography , Sodium/metabolism , Synaptic Transmission , Aged , Alzheimer Disease/metabolism , Alzheimer Disease/physiopathology , Carbolines , Cognitive Dysfunction/metabolism , Cognitive Dysfunction/physiopathology , Female , Humans , Magnetic Resonance Imaging , Male , Sodium/radiation effects , tau Proteins/metabolism
11.
Nature ; 515(7527): 355-64, 2014 Nov 20.
Article in English | MEDLINE | ID: mdl-25409824

ABSTRACT

The laboratory mouse shares the majority of its protein-coding genes with humans, making it the premier model organism in biomedical research, yet the two mammals differ in significant ways. To gain greater insights into both shared and species-specific transcriptional and cellular regulatory programs in the mouse, the Mouse ENCODE Consortium has mapped transcription, DNase I hypersensitivity, transcription factor binding, chromatin modifications and replication domains throughout the mouse genome in diverse cell and tissue types. By comparing with the human genome, we not only confirm substantial conservation in the newly annotated potential functional sequences, but also find a large degree of divergence of sequences involved in transcriptional regulation, chromatin state and higher order chromatin organization. Our results illuminate the wide range of evolutionary forces acting on genes and their regulatory regions, and provide a general resource for research into mammalian biology and mechanisms of human diseases.


Subject(s)
Genome/genetics , Genomics , Mice/genetics , Molecular Sequence Annotation , Animals , Cell Lineage/genetics , Chromatin/genetics , Chromatin/metabolism , Conserved Sequence/genetics , DNA Replication/genetics , Deoxyribonuclease I/metabolism , Gene Expression Regulation/genetics , Gene Regulatory Networks/genetics , Genome-Wide Association Study , Humans , RNA/genetics , Regulatory Sequences, Nucleic Acid/genetics , Species Specificity , Transcription Factors/metabolism , Transcriptome/genetics
12.
Nature ; 512(7515): 445-8, 2014 Aug 28.
Article in English | MEDLINE | ID: mdl-25164755

ABSTRACT

The transcriptome is the readout of the genome. Identifying common features in it across distant species can reveal fundamental principles. To this end, the ENCODE and modENCODE consortia have generated large amounts of matched RNA-sequencing data for human, worm and fly. Uniform processing and comprehensive annotation of these data allow comparison across metazoan phyla, extending beyond earlier within-phylum transcriptome comparisons and revealing ancient, conserved features. Specifically, we discover co-expression modules shared across animals, many of which are enriched in developmental genes. Moreover, we use expression patterns to align the stages in worm and fly development and find a novel pairing between worm embryo and fly pupae, in addition to the embryo-to-embryo and larvae-to-larvae pairings. Furthermore, we find that the extent of non-canonical, non-coding transcription is similar in each organism, per base pair. Finally, we find in all three organisms that the gene-expression levels, both coding and non-coding, can be quantitatively predicted from chromatin features at the promoter using a 'universal model' based on a single set of organism-independent parameters.


Subject(s)
Caenorhabditis elegans/genetics , Drosophila melanogaster/genetics , Gene Expression Profiling , Transcriptome/genetics , Animals , Caenorhabditis elegans/embryology , Caenorhabditis elegans/growth & development , Chromatin/genetics , Cluster Analysis , Drosophila melanogaster/growth & development , Gene Expression Regulation, Developmental/genetics , Histones/metabolism , Humans , Larva/genetics , Larva/growth & development , Models, Genetic , Molecular Sequence Annotation , Promoter Regions, Genetic/genetics , Pupa/genetics , Pupa/growth & development , RNA, Untranslated/genetics , Sequence Analysis, RNA
13.
Ann Neurol ; 83(2): 387-405, 2018 02.
Article in English | MEDLINE | ID: mdl-29369398

ABSTRACT

OBJECTIVE: Recent studies have underlined the effect of systemic inflammation on the pathophysiology of Alzheimer's disease (AD). Neutrophils are key components of early innate immunity and contribute to uncontrolled systemic inflammation if not tightly regulated. The aim of our study was to fully characterize human circulating neutrophils at different disease stages in AD. METHODS: We analyzed neutrophil phenotypes and functions in 42 patients with AD (16 with mild cognitive impairment and 26 with dementia), and compared them to 22 age-matched healthy subjects. This study was performed directly in whole blood to avoid issues with data interpretation related to cell isolation procedures. RESULTS: Blood samples from AD patients with dementia revealed neutrophil hyperactivation associated with increased reactive oxygen species production and increased levels of intravascular neutrophil extravascular traps. The homeostasis of circulating neutrophils in these patients also changed: The ratio between the harmful hyperreactive CXCR4high /CD62Llow senescent and the CD16bright /CD62Ldim immunosuppressive neutrophil subsets rose in the later stage of the disease. These abnormalities were greater in fast-decliner than in slow-decliner patients. INTERPRETATION: Our results indicate that the inflammatory properties of circulating neutrophils shift as the percentage of aged neutrophils expands in patients with AD-changes that may play an instrumental role in establishing systemic chronic inflammation. Most important, our data strongly suggest that the neutrophil phenotype may be associated with the rate of cognitive decline and may thus constitute an innovative and prognostic blood biomarker in patients with AD. Ann Neurol 2018;83:387-405.


Subject(s)
Alzheimer Disease/immunology , Neutrophil Activation/immunology , Neutrophils/immunology , Aged , Aged, 80 and over , Cognitive Dysfunction/immunology , Disease Progression , Female , Humans , Longitudinal Studies , Male , Middle Aged
14.
Brain ; 141(6): 1855-1870, 2018 06 01.
Article in English | MEDLINE | ID: mdl-29608645

ABSTRACT

Although brain neuroinflammation may play an instrumental role in the pathophysiology of Alzheimer's disease, its actual impact on disease progression remains controversial, being reported as either detrimental or protective. This work aimed at investigating the temporal relationship between microglial activation and clinical progression of Alzheimer's disease. First, in a large cohort of patients with Alzheimer's disease we analysed the predictive value of microglial activation assessed by 18F-DPA-714 PET imaging on functional, cognitive and MRI biomarkers outcomes after a 2-year follow-up. Second, we analysed the longitudinal progression of 18F-DPA-714 binding in patients with Alzheimer's disease by comparison with controls, and assessed its influence on clinical progression. At baseline, all participants underwent a clinical assessment, brain MRI, 11C-PiB, 18F-DPA-714 PET imaging and TSPO genotyping. Participants were followed-up annually for 2 years. At the end of the study, subjects were asked to repeat a second 18F-DPA-714-PET imaging. Initial 18F-DPA-714 binding was higher in prodromal (n = 33) and in demented patients with Alzheimer's disease (n = 19) compared to controls (n = 17). After classifying patients into slow and fast decliners according to functional (Clinical Dementia Rating change) or cognitive (Mini-Mental State Examination score decline) outcomes, we found a higher initial 18F-DPA-714 binding in slow than fast decliners. Negative correlations were observed between initial 18F-DPA-714 binding and the Clinical Dementia Rating Sum of Boxes score increase, the MMSE score loss and the progression of hippocampal atrophy. This suggests that higher initial 18F-DPA-714 binding is associated with better clinical prognosis. Twenty-four patients with Alzheimer's disease and 15 control subjects performed a second DPA-PET. We observed an increase of 18F-DPA-714 in patients with Alzheimer's disease as compared with controls (mean 13.2% per year versus 4.2%) both at the prodromal (15.8%) and at the demented stages (8.3%). The positive correlations between change in 18F-DPA-714 binding over time and the three clinical outcome measures (Clinical Dementia Rating, Mini-Mental State Examination, hippocampal atrophy) suggested a detrimental effect on clinical Alzheimer's disease progression of increased neuroinflammation after the initial PET examination, without correlation with PiB-PET uptake at baseline. High initial 18F-DPA-714 binding was correlated with a low subsequent increase of microglial activation and favourable clinical evolution, whereas the opposite profile was observed when initial 18F-DPA-714 binding was low, independently of disease severity at baseline. Taken together, our results support a pathophysiological model involving two distinct profiles of microglial activation signatures with different dynamics, which differentially impact on disease progression and may vary depending on patients rather than disease stages.


Subject(s)
Alzheimer Disease/pathology , Alzheimer Disease/physiopathology , Disease Progression , Hippocampus/diagnostic imaging , Microglia/pathology , Aged , Aged, 80 and over , Alzheimer Disease/diagnostic imaging , Amyloid beta-Peptides/metabolism , Analysis of Variance , Aniline Compounds/pharmacokinetics , Brain Mapping , Female , Humans , Longitudinal Studies , Magnetic Resonance Imaging , Male , Mental Status Schedule , Middle Aged , Neuropsychological Tests , Organoplatinum Compounds/metabolism , Positron-Emission Tomography , Prospective Studies , Pyrazoles/pharmacokinetics , Pyrimidines/pharmacokinetics , Radiopharmaceuticals/pharmacokinetics , Thiazoles/pharmacokinetics
15.
J Neural Transm (Vienna) ; 125(5): 847-867, 2018 05.
Article in English | MEDLINE | ID: mdl-28516240

ABSTRACT

Increasing evidence suggests that neuroinflammation contributes to the pathophysiology of many neurodegenerative diseases, especially Alzheimer's disease (AD). Molecular imaging by PET may be a useful tool to assess neuroinflammation in vivo, thus helping to decipher the complex role of inflammatory processes in the pathophysiology of neurodegenerative diseases and providing a potential means of monitoring the effect of new therapeutic approaches. For this objective, the main target of PET studies is the 18 kDa translocator protein (TSPO), as it is overexpressed by activated microglia. In the present review, we describe the most widely used PET tracers targeting the TSPO, the methodological issues in tracer quantification and summarize the results obtained by TSPO PET imaging in AD, as well as in neurodegenerative disorders associated with AD, in psychiatric disorders and ageing. We also briefly describe alternative PET targets and imaging modalities to study neuroinflammation. Lastly, we question the meaning of PET imaging data in the context of a highly complex and multifaceted role of neuroinflammation in neurodegenerative diseases. This overview leads to the conclusion that PET imaging of neuroinflammation is a promising way of deciphering the enigma of the pathophysiology of AD and of monitoring the effect of new therapies.


Subject(s)
Alzheimer Disease/diagnostic imaging , Inflammation/diagnostic imaging , Neuroimaging/methods , Positron-Emission Tomography/methods , Alzheimer Disease/pathology , Humans , Inflammation/pathology
16.
Nature ; 489(7414): 101-8, 2012 Sep 06.
Article in English | MEDLINE | ID: mdl-22955620

ABSTRACT

Eukaryotic cells make many types of primary and processed RNAs that are found either in specific subcellular compartments or throughout the cells. A complete catalogue of these RNAs is not yet available and their characteristic subcellular localizations are also poorly understood. Because RNA represents the direct output of the genetic information encoded by genomes and a significant proportion of a cell's regulatory capabilities are focused on its synthesis, processing, transport, modification and translation, the generation of such a catalogue is crucial for understanding genome function. Here we report evidence that three-quarters of the human genome is capable of being transcribed, as well as observations about the range and levels of expression, localization, processing fates, regulatory regions and modifications of almost all currently annotated and thousands of previously unannotated RNAs. These observations, taken together, prompt a redefinition of the concept of a gene.


Subject(s)
DNA/genetics , Encyclopedias as Topic , Genome, Human/genetics , Molecular Sequence Annotation , Regulatory Sequences, Nucleic Acid/genetics , Transcription, Genetic/genetics , Transcriptome/genetics , Alleles , Cell Line , DNA, Intergenic/genetics , Enhancer Elements, Genetic , Exons/genetics , Gene Expression Profiling , Genes/genetics , Genomics , Humans , Polyadenylation/genetics , Protein Isoforms/genetics , RNA/biosynthesis , RNA/genetics , RNA Editing/genetics , RNA Splicing/genetics , Repetitive Sequences, Nucleic Acid/genetics , Sequence Analysis, RNA
17.
Alzheimer Dis Assoc Disord ; 31(1): 8-12, 2017.
Article in English | MEDLINE | ID: mdl-27680780

ABSTRACT

The central cholinergic system undergoes changes during the physiological process of aging and the pathologic process of Alzheimer disease (AD). We aimed to analyze the impairment of cholinergic pathways by positron emission tomography using the [F]-F-A-85380 (FA85) tracer, which has a high affinity for nicotinic acetylcholine receptors (nAChRs). Aging was assessed by comparing young (n=10) and elderly (n=4) healthy subjects, and the pathologic process of AD was assessed by comparing elderly controls and age-matched AD patients (n=8). We measured an index of the nAChR density in the cortex and the hippocampus and the total number of FA85-binding sites by taking into account the volume changes. In AD, the nAChR density was preserved in both the cortex and hippocampus. The total estimated number of FA85-binding sites was decreased in the hippocampus despite the lack of a significant loss of volume, whereas the difference in the cortex did not withstand the adjustment for multiple comparisons despite a significant loss of volume. In contrast, in aging, the estimated number of FA85-binding sites was decreased in both the cortex and hippocampus with significant hippocampal atrophy. These findings suggest a preferential impairment of cholinergic pathways in the cortex during aging, whereas in AD, this damage predominated in the hippocampus with a potential compensatory cholinergic effect in the cortex.


Subject(s)
Aging/physiology , Alzheimer Disease/pathology , Azetidines , Positron-Emission Tomography/methods , Pyridines , Receptors, Nicotinic , Adult , Aged , Alzheimer Disease/diagnostic imaging , Alzheimer Disease/metabolism , Atrophy/pathology , Binding, Competitive/physiology , Brain/diagnostic imaging , Brain/pathology , Cerebral Cortex/pathology , Female , Hippocampus/pathology , Humans , Magnetic Resonance Imaging , Male
18.
Brain ; 139(Pt 4): 1252-64, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26984188

ABSTRACT

While emerging evidence suggests that neuroinflammation plays a crucial role in Alzheimer's disease, the impact of the microglia response in Alzheimer's disease remains a matter of debate. We aimed to study microglial activation in early Alzheimer's disease and its impact on clinical progression using a second-generation 18-kDa translocator protein positron emission tomography radiotracer together with amyloid imaging using Pittsburgh compound B positron emission tomography. We enrolled 96 subjects, 64 patients with Alzheimer's disease and 32 controls, from the IMABio3 study, who had both (11)C-Pittsburgh compound B and (18)F-DPA-714 positron emission tomography imaging. Patients with Alzheimer's disease were classified as prodromal Alzheimer's disease (n = 38) and Alzheimer's disease dementia (n = 26). Translocator protein-binding was measured using a simple ratio method with cerebellar grey matter as reference tissue, taking into account regional atrophy. Images were analysed at the regional (volume of interest) and at the voxel level. Translocator protein genotyping allowed the classification of all subjects in high, mixed and low affinity binders. Thirty high+mixed affinity binders patients with Alzheimer's disease were dichotomized into slow decliners (n = 10) or fast decliners (n = 20) after 2 years of follow-up. All patients with Alzheimer's disease had an amyloid positive Pittsburgh compound B positron emission tomography. Among controls, eight had positive amyloid scans (n = 6 high+mixed affinity binders), defined as amyloidosis controls, and were analysed separately. By both volumes of interest and voxel-wise comparison, 18-kDa translocator protein-binding was higher in high affinity binders, mixed affinity binders and high+mixed affinity binders Alzheimer's disease groups compared to controls, especially at the prodromal stage, involving the temporo-parietal cortex. Translocator protein-binding was positively correlated with Mini-Mental State Examination scores and grey matter volume, as well as with Pittsburgh compound B binding. Amyloidosis controls displayed higher translocator protein-binding than controls, especially in the frontal cortex. We found higher translocator protein-binding in slow decliners than fast decliners, with no difference in Pittsburgh compound B binding. Microglial activation appears at the prodromal and possibly at the preclinical stage of Alzheimer's disease, and seems to play a protective role in the clinical progression of the disease at these early stages. The extent of microglial activation appears to differ between patients, and could explain the overlap in translocator protein binding values between patients with Alzheimer's disease and amyloidosis controls.


Subject(s)
Alzheimer Disease/diagnostic imaging , Alzheimer Disease/metabolism , Fluorine Radioisotopes , Microglia/metabolism , Positron-Emission Tomography/methods , Pyrazoles , Pyrimidines , Aged , Aged, 80 and over , Brain/metabolism , Brain/pathology , Cohort Studies , Female , Follow-Up Studies , Humans , Longitudinal Studies , Male , Middle Aged , Prospective Studies
19.
Brain Cogn ; 113: 172-183, 2017 04.
Article in English | MEDLINE | ID: mdl-28257971

ABSTRACT

Living in a complex and multisensory environment demands constant interaction between perception and action. In everyday life it is common to combine efficiently simultaneous signals coming from different modalities. There is evidence of a multisensory benefit in a variety of laboratory tasks (temporal judgement, reaction time tasks). It is less clear if this effect extends to ecological tasks, such as walking. Furthermore, benefits of multimodal stimulation are linked to temporal properties such as the temporal window of integration and temporal recalibration. These properties have been examined in tasks involving single, non-repeating stimulus presentations. Here we investigate the same temporal properties in the context of a rhythmic task, namely audio-tactile stimulation during walking. The effect of audio-tactile rhythmic cues on gait variability and the ability to synchronize to the cues was studied in young adults. Participants walked with rhythmic cues presented at different stimulus-onset asynchronies. We observed a multisensory benefit by comparing audio-tactile to unimodal stimulation. Moreover, both the temporal window of integration and temporal recalibration mediated the response to multimodal stimulation. In sum, rhythmic behaviours obey the same principles as temporal discrimination and detection behaviours and thus can also benefit from multimodal stimulation.


Subject(s)
Auditory Perception/physiology , Touch Perception/physiology , Walking/physiology , Acoustic Stimulation , Adult , Cues , Female , Gait , Humans , Male , Periodicity , Photic Stimulation , Physical Stimulation , Reaction Time/physiology , Touch , Visual Perception/physiology , Walking/psychology , Young Adult
20.
Exp Brain Res ; 234(2): 463-74, 2016 Feb.
Article in English | MEDLINE | ID: mdl-26525707

ABSTRACT

The brain has the remarkable ability to bind together inputs from different sensory origin into a coherent percept. Behavioral benefits can result from such ability, e.g., a person typically responds faster and more accurately to cross-modal stimuli than to unimodal stimuli. To date, it is, however, largely unknown whether such multisensory benefits, shown for discrete reactive behaviors, generalize to the continuous coordination of movements. The present study addressed multisensory integration from the perspective of bimanual coordination dynamics, where the perceptual activity no longer triggers a single response but continuously guides the motor action. The task consisted in coordinating anti-symmetrically the continuous flexion-extension of the index fingers, while synchronizing with an external pacer. Three different configurations of metronome were tested, for which we examined whether a cross-modal pacing (audio-tactile beats) improved the stability of the coordination in comparison with unimodal pacing condition (auditory or tactile beats). We found a more stable bimanual coordination for cross-modal pacing, but only when the metronome configuration directly matched the anti-symmetric coordination pattern. We conclude that multisensory integration can benefit the continuous coordination of movements; however, this is constrained by whether the perceptual and motor activities match in space and time.


Subject(s)
Acoustic Stimulation/methods , Auditory Perception/physiology , Fingers/physiology , Motor Activity/physiology , Psychomotor Performance/physiology , Touch/physiology , Adult , Humans , Male , Movement/physiology , Reaction Time/physiology , Young Adult
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