RESUMEN
Truncating genetic variants of SORL1, encoding the endosome recycling receptor SORLA, have been accepted as causal of Alzheimer's disease (AD). However, most genetic variants observed in SORL1 are missense variants, for which it is complicated to determine the pathogenicity level because carriers come from pedigrees too small to be informative for penetrance estimations. Here, we describe three unrelated families in which the SORL1 coding missense variant rs772677709, that leads to a p.Y1816C substitution, segregates with Alzheimer's disease. Further, we investigate the effect of SORLA p.Y1816C on receptor maturation, cellular localization, and trafficking in cell-based assays. Under physiological circumstances, SORLA dimerizes within the endosome, allowing retromer-dependent trafficking from the endosome to the cell surface, where the luminal part is shed into the extracellular space (sSORLA). Our results showed that the p.Y1816C mutant impairs SORLA homodimerization in the endosome, leading to decreased trafficking to the cell surface and less sSORLA shedding. These trafficking defects of the mutant receptor can be rescued by the expression of the SORLA 3Fn-minireceptor. Finally, we find that iPSC-derived neurons with the engineered p.Y1816C mutation have enlarged endosomes, a defining cytopathology of AD. Our studies provide genetic as well as functional evidence that the SORL1 p.Y1816C variant is causal for AD. The partial penetrance of the mutation suggests this mutation should be considered in clinical genetic screening of multiplex early-onset AD families.
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Enfermedad de Alzheimer , Endosomas , Proteínas Relacionadas con Receptor de LDL , Proteínas de Transporte de Membrana , Linaje , Humanos , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/patología , Endosomas/metabolismo , Proteínas Relacionadas con Receptor de LDL/genética , Proteínas Relacionadas con Receptor de LDL/metabolismo , Femenino , Masculino , Proteínas de Transporte de Membrana/genética , Proteínas de Transporte de Membrana/metabolismo , Mutación Missense , Transporte de Proteínas , Multimerización de Proteína , Anciano , Persona de Mediana Edad , Células HEK293RESUMEN
A recent large genome-wide association study has identified EGFR (encoding the epidermal growth factor EGFR) as a new genetic risk factor for late-onset AD. SHIP2, encoded by INPPL1, is taking part in the signalling and interactome of several growth factor receptors, such as the EGFR. While INPPL1 has been identified as one of the most significant genes whose RNA expression correlates with cognitive decline, the potential alteration of SHIP2 expression and localization during the progression of AD remains largely unknown. Here we report that gene expression of both EGFR and INPPL1 was upregulated in AD brains. SHIP2 immunoreactivity was predominantly detected in plaque-associated astrocytes and dystrophic neurites and its increase was correlated with amyloid load in the brain of human AD and of 5xFAD transgenic mouse model of AD. While mRNA of INPPL1 was increased in AD, SHIP2 protein undergoes a significant solubility change being depleted from the soluble fraction of AD brain homogenates and co-enriched with EGFR in the insoluble fraction. Using FRET-based flow cytometry biosensor assay for tau-tau interaction, overexpression of SHIP2 significantly increased the FRET signal while siRNA-mediated downexpression of SHIP2 significantly decreased FRET signal. Genetic association analyses suggest that some variants in INPPL1 locus are associated with the level of CSF pTau. Our data support the hypothesis that SHIP2 is an intermediate key player of EGFR and AD pathology linking amyloid and tau pathologies in human AD.
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Enfermedad de Alzheimer , Encéfalo , Progresión de la Enfermedad , Receptores ErbB , Fosfatidilinositol-3,4,5-Trifosfato 5-Fosfatasas , Anciano , Anciano de 80 o más Años , Animales , Femenino , Humanos , Masculino , Ratones , Enfermedad de Alzheimer/patología , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/metabolismo , Encéfalo/patología , Encéfalo/metabolismo , Receptores ErbB/genética , Receptores ErbB/metabolismo , Expresión Génica , Ratones Transgénicos , Fosfatidilinositol-3,4,5-Trifosfato 5-Fosfatasas/genética , Fosfatidilinositol-3,4,5-Trifosfato 5-Fosfatasas/metabolismo , Solubilidad , Proteínas tau/metabolismo , Proteínas tau/genéticaRESUMEN
Alzheimer's disease (AD) is a growing problem worldwide. Since ABCA7's identification as a risk gene, it has been extensively researched for its role in the disease. We review its recently characterized structure and what the mechanistic insights teach us about its function. We furthermore provide an overview of identified ABCA7 mutations, their presence in different ancestries and protein domains and how they might cause AD. For ABCA7 PTC variants and a VNTR expansion, haploinsufficiency is proposed as the most likely mode-of-action, although splice events could further influence disease risk. Overall, the need to better understand expression of canonical ABCA7 and its isoforms in disease is indicated. Finally, ABCA7's potential functions in lipid metabolism, phagocytosis, amyloid deposition, and the interplay between these three, is described. To conclude, in this review, we provide a comprehensive overview and discussion about the current knowledge on ABCA7 in AD, and what research questions remain. HIGHLIGHTS: Alzheimer's risk-increasing variants in ABCA7 can be found in up to 7% of AD patients. We review the recently characterized protein structure of ABCA7. We present latest insights in genetics, expression patterns, and functions of ABCA7.
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Transportadoras de Casetes de Unión a ATP , Enfermedad de Alzheimer , Humanos , Enfermedad de Alzheimer/genética , Transportadoras de Casetes de Unión a ATP/genética , Predisposición Genética a la Enfermedad , Mutación , AnimalesRESUMEN
Alzheimer's disease (AD) is characterized by amyloid beta (Aß) plaques and hyperphosphorylated tau in the brain. Aß plaques precede cognitive impairments and can be detected through amyloid-positron emission tomography (PET) or in cerebrospinal fluid (CSF). Assessing the plasma Aß42/Aß40 ratio seems promising for non-invasive and cost-effective detection of brain Aß accumulation. This approach involves some challenges, including the accuracy of blood-based biomarker measurements and the establishment of clear, standardized thresholds to categorize the risk of developing brain amyloid pathology. Plasma Aß42/Aß40 ratio was measured in 277 volunteers without dementia, 70 AD patients and 18 non-AD patients using single-molecule array. Patients (n = 88) and some volunteers (n = 66) were subject to evaluation of amyloid status by CSF Aß quantification or PET analysis. Thresholds of plasma Aß42/Aß40 ratio were determined based on a Gaussian mixture model, a decision tree, and the Youden's index. The 0.0472 threshold, the one with the highest sensitivity, was retained for general population without dementia screening, and the 0.0450 threshold was retained for research and clinical trials recruitment, aiming to minimize the need for CSF or PET analyses to identify amyloid-positive individuals. These findings offer a promising step towards a cost-effective method for identifying individuals at risk of developing AD.
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Enfermedad de Alzheimer , Péptidos beta-Amiloides , Humanos , Proteínas Amiloidogénicas , Tomografía de Emisión de Positrones , Enfermedad de Alzheimer/diagnóstico , Encéfalo , Placa AmiloideRESUMEN
Alzheimer's disease (AD) biomarkers represent several neurodegenerative processes, such as synaptic dysfunction, neuronal inflammation and injury, as well as amyloid pathology. We performed an exome-wide rare variant analysis of six AD biomarkers (ß-amyloid, total/phosphorylated tau, NfL, YKL-40, and Neurogranin) to discover genes associated with these markers. Genetic and biomarker information was available for 480 participants from two studies: EMIF-AD and ADNI. We applied a principal component (PC) analysis to derive biomarkers combinations, which represent statistically independent biological processes. We then tested whether rare variants in 9576 protein-coding genes associate with these PCs using a Meta-SKAT test. We also tested whether the PCs are intermediary to gene effects on AD symptoms with a SMUT test. One PC loaded on NfL and YKL-40, indicators of neuronal injury and inflammation. Four genes were associated with this PC: IFFO1, DTNB, NLRC3, and SLC22A10. Mediation tests suggest, that these genes also affect dementia symptoms via inflammation/injury. We also observed an association between a PC loading on Neurogranin, a marker for synaptic functioning, with GABBR2 and CASZ1, but no mediation effects. The results suggest that rare variants in IFFO1, DTNB, NLRC3, and SLC22A10 heighten susceptibility to neuronal injury and inflammation, potentially by altering cytoskeleton structure and immune activity disinhibition, resulting in an elevated dementia risk. GABBR2 and CASZ1 were associated with synaptic functioning, but mediation analyses suggest that the effect of these two genes on synaptic functioning is not consequential for AD development.
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Enfermedad de Alzheimer , Enfermedad de Alzheimer/diagnóstico , Péptidos beta-Amiloides/genética , Biomarcadores , Proteína 1 Similar a Quitinasa-3/genética , Proteínas de Unión al ADN , Ácido Ditionitrobenzoico , Humanos , Inflamación/genética , Péptidos y Proteínas de Señalización Intercelular , Neurogranina/genética , Factores de Transcripción , Proteínas tauRESUMEN
INTRODUCTION: This study employed an integrative system and causal inference approach to explore molecular signatures in blood and CSF, the amyloid/tau/neurodegeneration [AT(N)] framework, mild cognitive impairment (MCI) conversion to Alzheimer's disease (AD), and genetic risk for AD. METHODS: Using the European Medical Information Framework (EMIF)-AD cohort, we measured 696 proteins in cerebrospinal fluid (n = 371), 4001 proteins in plasma (n = 972), 611 metabolites in plasma (n = 696), and genotyped whole-blood (7,778,465 autosomal single nucleotide epolymorphisms, n = 936). We investigated associations: molecular modules to AT(N), module hubs with AD Polygenic Risk scores and APOE4 genotypes, molecular hubs to MCI conversion and probed for causality with AD using Mendelian randomization (MR). RESULTS: AT(N) framework associated with protein and lipid hubs. In plasma, Proprotein Convertase Subtilisin/Kexin Type 7 showed evidence for causal associations with AD. AD was causally associated with Reticulocalbin 2 and sphingomyelins, an association driven by the APOE isoform. DISCUSSION: This study reveals multi-omics networks associated with AT(N) and causal AD molecular candidates.
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Enfermedad de Alzheimer , Disfunción Cognitiva , Humanos , Péptidos beta-Amiloides/líquido cefalorraquídeo , Proteínas tau/líquido cefalorraquídeo , Multiómica , Biomarcadores/líquido cefalorraquídeo , Disfunción Cognitiva/líquido cefalorraquídeo , Fragmentos de Péptidos/líquido cefalorraquídeoRESUMEN
INTRODUCTION: Despite increasing evidence of a role of rare genetic variation in the risk of Alzheimer's disease (AD), limited attention has been paid to its contribution to AD-related biomarker traits indicative of AD-relevant pathophysiological processes. METHODS: We performed whole-exome gene-based rare-variant association studies (RVASs) of 17 AD-related traits on whole-exome sequencing (WES) data generated in the European Medical Information Framework for Alzheimer's Disease Multimodal Biomarker Discovery (EMIF-AD MBD) study (n = 450) and whole-genome sequencing (WGS) data from ADNI (n = 808). RESULTS: Mutation screening revealed a novel probably pathogenic mutation (PSEN1 p.Leu232Phe). Gene-based RVAS revealed the exome-wide significant contribution of rare coding variation in RBKS and OR7A10 to cognitive performance and protection against left hippocampal atrophy, respectively. DISCUSSION: The identification of these novel gene-trait associations offers new perspectives into the role of rare coding variation in the distinct pathophysiological processes culminating in AD, which may lead to identification of novel therapeutic and diagnostic targets.
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Enfermedad de Alzheimer , Humanos , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/diagnóstico , Exoma/genética , Estudios de Asociación Genética , Fenotipo , BiomarcadoresRESUMEN
We sequenced the genome of the Yoruban reference individual NA19240 on the long-read sequencing platform Oxford Nanopore PromethION for evaluation and benchmarking of recently published aligners and germline structural variant calling tools, as well as a comparison with the performance of structural variant calling from short-read sequencing data. The structural variant caller Sniffles after NGMLR or minimap2 alignment provides the most accurate results, but additional confidence or sensitivity can be obtained by a combination of multiple variant callers. Sensitive and fast results can be obtained by minimap2 for alignment and a combination of Sniffles and SVIM for variant identification. We describe a scalable workflow for identification, annotation, and characterization of tens of thousands of structural variants from long-read genome sequencing of an individual or population. By discussing the results of this well-characterized reference individual, we provide an approximation of what can be expected in future long-read sequencing studies aiming for structural variant identification.
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Variación Genética , Genoma Humano , Análisis de Secuencia de ADN/instrumentación , Benchmarking , Línea Celular Tumoral , Biología Computacional , HumanosRESUMEN
Over 25 genes are known to affect the risk of developing Alzheimer disease (AD), the most common neurodegenerative dementia. However, mechanistic insights and improved disease management remains limited, due to difficulties in determining the functional consequences of genetic associations. Transcriptomics is increasingly being used to corroborate or enhance interpretation of genetic discoveries. These approaches, which include second and third generation sequencing, single-cell sequencing, and bioinformatics, reveal allele-specific events connecting AD risk genes to expression profiles, and provide converging evidence of pathophysiological pathways underlying AD. Simultaneously, they highlight brain region- and cell-type-specific expression patterns, and alternative splicing events that affect the straightforward relation between a genetic variant and AD, re-emphasizing the need for an integrated approach of genetics and transcriptomics in understanding AD.
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Enfermedad de Alzheimer/genética , Encéfalo/metabolismo , Redes y Vías Metabólicas/genética , Transcriptoma/genética , Enfermedad de Alzheimer/patología , Encéfalo/patología , Mapeo Encefálico/métodos , Biología Computacional , Expresión Génica/genética , Predisposición Genética a la Enfermedad , Humanos , Análisis de Secuencia de ADN/métodos , Análisis de la Célula Individual/métodosRESUMEN
INTRODUCTION: This study sought to discover and replicate plasma proteomic biomarkers relating to Alzheimer's disease (AD) including both the "ATN" (amyloid/tau/neurodegeneration) diagnostic framework and clinical diagnosis. METHODS: Plasma proteins from 972 subjects (372 controls, 409 mild cognitive impairment [MCI], and 191 AD) were measured using both SOMAscan and targeted assays, including 4001 and 25 proteins, respectively. RESULTS: Protein co-expression network analysis of SOMAscan data revealed the relation between proteins and "N" varied across different neurodegeneration markers, indicating that the ATN variants are not interchangeable. Using hub proteins, age, and apolipoprotein E ε4 genotype discriminated AD from controls with an area under the curve (AUC) of 0.81 and MCI convertors from non-convertors with an AUC of 0.74. Targeted assays replicated the relation of four proteins with the ATN framework and clinical diagnosis. DISCUSSION: Our study suggests that blood proteins can predict the presence of AD pathology as measured in the ATN framework as well as clinical diagnosis.
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Enfermedad de Alzheimer , Péptidos beta-Amiloides/sangre , Biomarcadores/sangre , Proteínas Sanguíneas , Proteómica , Proteínas tau/sangre , Anciano , Enfermedad de Alzheimer/sangre , Enfermedad de Alzheimer/patología , Apolipoproteína E4/sangre , Apolipoproteína E4/genética , Disfunción Cognitiva/sangre , Disfunción Cognitiva/patología , Europa (Continente) , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
INTRODUCTION: Neurofilament light (NfL), chitinase-3-like protein 1 (YKL-40), and neurogranin (Ng) are biomarkers for Alzheimer's disease (AD) to monitor axonal damage, astroglial activation, and synaptic degeneration, respectively. METHODS: We performed genome-wide association studies (GWAS) using DNA and cerebrospinal fluid (CSF) samples from the EMIF-AD Multimodal Biomarker Discovery study for discovery, and the Alzheimer's Disease Neuroimaging Initiative study for validation analyses. GWAS were performed for all three CSF biomarkers using linear regression models adjusting for relevant covariates. RESULTS: We identify novel genome-wide significant associations between DNA variants in TMEM106B and CSF levels of NfL, and between CPOX and YKL-40. We confirm previous work suggesting that YKL-40 levels are associated with DNA variants in CHI3L1. DISCUSSION: Our study provides important new insights into the genetic architecture underlying interindividual variation in three AD-related CSF biomarkers. In particular, our data shed light on the sequence of events regarding the initiation and progression of neuropathological processes relevant in AD.
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Enfermedad de Alzheimer/genética , Biomarcadores/líquido cefalorraquídeo , Estudio de Asociación del Genoma Completo , Proteínas de la Membrana/genética , Proteínas del Tejido Nervioso/genética , Anciano , Proteína 1 Similar a Quitinasa-3/genética , Femenino , Humanos , Masculino , Proteínas de Neurofilamentos/genética , Neurogranina/líquido cefalorraquídeoRESUMEN
Genome-wide association studies (GWAS) have identified PICALM as one of the most significant susceptibility loci for late-onset Alzheimer's disease (AD) after APOE and BIN1. PICALM is a clathrin-adaptor protein and plays critical roles in clathrin-mediated endocytosis and in autophagy. PICALM modulates brain amyloid ß (Aß) pathology and tau accumulation. We have previously reported that soluble PICALM protein level is reduced in correlation with abnormalities of autophagy markers in the affected brain areas of neurodegenerative diseases including AD, sporadic tauopathies and familial cases of frontotemporal lobar degeneration with tau-immunoreactive inclusions (FTLD-tau) with mutations in the microtubule-associated protein tau (MAPT) gene. It remains unclarified whether in vivo PICALM reduction could either trigger or influence tau pathology progression in the brain. In this study, we confirmed a significant reduction of soluble PICALM protein and autophagy deficits in the post-mortem human brains of FTLD-tau-MAPT (P301L, S364S and L266V). We generated a novel transgenic mouse line named Tg30xPicalm+/- by crossing Tg30 tau transgenic mice with Picalm-haploinsufficient mice to test whether Picalm reduction may modulate tau pathology. While Picalm haploinsufficiency did not lead to any motor phenotype or detectable tau pathology in mouse brains, Tg30xPicalm+/- mice developed markedly more severe motor deficits than Tg30 by the age of 9 months. Tg30xPicalm+/- had significantly higher pathological tau levels in the brain, an increased density of neurofibrillary tangles compared to Tg30 mice and increased abnormalities of autophagy markers. Our results demonstrate that Picalm haploinsufficiency in transgenic Tg30 mice significantly aggravated tau pathologies and tau-mediated neurodegeneration, supporting a role for changes in Picalm expression as a risk/sensitizing factor for development of tau pathology and as a mechanism underlying the AD risk associated to PICALM.
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Proteínas de Ensamble de Clatrina Monoméricas/genética , Tauopatías/genética , Tauopatías/patología , Animales , Encéfalo/patología , Modelos Animales de Enfermedad , Femenino , Demencia Frontotemporal/metabolismo , Haploinsuficiencia , Humanos , Masculino , Ratones , Ratones Transgénicos , Persona de Mediana Edad , Proteínas de Ensamble de Clatrina Monoméricas/metabolismo , Tauopatías/metabolismo , Proteínas tau/genéticaRESUMEN
Genes associated with immune response and inflammation have been identified as genetic risk factors for late-onset Alzheimer´s disease (LOAD). The rare R47H variant within triggering receptor expressed on myeloid cells 2 (TREM2) has been shown to increase the risk for developing Alzheimer's disease (AD) 2-3-fold. Here, we report the generation and characterization of a model of late-onset Alzheimer's disease (LOAD) using lymphoblast-derived induced pluripotent stem cells (iPSCs) from patients carrying the TREM2 R47H mutation, as well as from control individuals without dementia. All iPSCs efficiently differentiated into mature neuronal cultures, however AD neuronal cultures showed a distinct gene expression profile. Furthermore, manipulation of the iPSC-derived neuronal cultures with an Aß-S8C dimer highlighted metabolic pathways, phagosome and immune response as the most perturbed pathways in AD neuronal cultures. Through the construction of an Aß-induced gene regulatory network, we were able to identify an Aß signature linked to protein processing in the endoplasmic reticulum (ER), which emphasized ER-stress, as a potential causal role in LOAD. Overall, this study has shown that our AD-iPSC based model can be used for in-depth studies to better understand the molecular mechanisms underlying the etiology of LOAD and provides new opportunities for screening of potential therapeutic targets.
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Enfermedad de Alzheimer/genética , Glicoproteínas de Membrana/genética , Receptores Inmunológicos/genética , Anciano , Enfermedad de Alzheimer/metabolismo , Péptidos beta-Amiloides/genética , Péptidos beta-Amiloides/metabolismo , Encéfalo/metabolismo , Diferenciación Celular/genética , Retículo Endoplásmico/genética , Retículo Endoplásmico/metabolismo , Femenino , Redes Reguladoras de Genes/genética , Predisposición Genética a la Enfermedad/genética , Variación Genética/genética , Humanos , Masculino , Glicoproteínas de Membrana/metabolismo , Modelos Biológicos , Mutación/genética , Células Mieloides/metabolismo , Neuronas/metabolismo , Células Madre Pluripotentes/metabolismo , Células Madre Pluripotentes/fisiología , Receptores Inmunológicos/metabolismoRESUMEN
Genome-wide association studies (GWAS) originally identified ATP-binding cassette, sub-family A, member 7 (ABCA7), as a novel risk gene of Alzheimer's disease (AD). Since then, accumulating evidence from in vitro, in vivo, and human-based studies has corroborated and extended this association, promoting ABCA7 as one of the most important risk genes of both early-onset and late-onset AD, harboring both common and rare risk variants with relatively large effect on AD risk. Within this review, we provide a comprehensive assessment of the literature on ABCA7, with a focus on AD-related human -omics studies (e.g. genomics, transcriptomics, and methylomics). In European and African American populations, indirect ABCA7 GWAS associations are explained by expansion of an ABCA7 variable number tandem repeat (VNTR), and a common premature termination codon (PTC) variant, respectively. Rare ABCA7 PTC variants are strongly enriched in AD patients, and some of these have displayed inheritance patterns resembling autosomal dominant AD. In addition, rare missense variants are more frequent in AD patients than healthy controls, whereas a common ABCA7 missense variant may protect from disease. Methylation at several CpG sites in the ABCA7 locus is significantly associated with AD. Furthermore, ABCA7 contains many different isoforms and ABCA7 splicing has been shown to associate with AD. Besides associations with disease status, these genetic and epigenetic ABCA7 markers also showed significant correlations with AD endophenotypes; in particular amyloid deposition and brain morphology. In conclusion, human-based -omics studies provide converging evidence of (partial) ABCA7 loss as an AD pathomechanism, and future studies should make clear if interventions on ABCA7 expression can serve as a valuable therapeutic target for AD.
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Transportadoras de Casetes de Unión a ATP/genética , Enfermedad de Alzheimer/genética , Transportadoras de Casetes de Unión a ATP/deficiencia , Transportadoras de Casetes de Unión a ATP/fisiología , Enfermedad de Alzheimer/etnología , Amiloide/metabolismo , Animales , Atrofia , Encéfalo/metabolismo , Encéfalo/patología , Codón sin Sentido , Cognición/fisiología , Islas de CpG , Metilación de ADN , Modelos Animales de Enfermedad , Etnicidad/genética , Femenino , Genes Dominantes , Predisposición Genética a la Enfermedad , Genómica , Humanos , Metabolismo de los Lípidos/genética , Masculino , Ratones , Repeticiones de Minisatélite , Mutación Missense , Polimorfismo de Nucleótido Simple , Riesgo , TranscriptomaRESUMEN
Emerging evidence suggested a converging mechanism in neurodegenerative brain diseases (NBD) involving early neuronal network dysfunctions and alterations in the homeostasis of neuronal firing as culprits of neurodegeneration. In this study, we used paired-end short-read and direct long-read whole genome sequencing to investigate an unresolved autosomal dominant dementia family significantly linked to 7q36. We identified and validated a chromosomal inversion of ca. 4 Mb, segregating on the disease haplotype and disrupting the coding sequence of dipeptidyl-peptidase 6 gene (DPP6). DPP6 resequencing identified significantly more rare variants-nonsense, frameshift, and missense-in early-onset Alzheimer's disease (EOAD, p value = 0.03, OR = 2.21 95% CI 1.05-4.82) and frontotemporal dementia (FTD, p = 0.006, OR = 2.59, 95% CI 1.28-5.49) patient cohorts. DPP6 is a type II transmembrane protein with a highly structured extracellular domain and is mainly expressed in brain, where it binds to the potassium channel Kv4.2 enhancing its expression, regulating its gating properties and controlling the dendritic excitability of hippocampal neurons. Using in vitro modeling, we showed that the missense variants found in patients destabilize DPP6 and reduce its membrane expression (p < 0.001 and p < 0.0001) leading to a loss of protein. Reduced DPP6 and/or Kv4.2 expression was also detected in brain tissue of missense variant carriers. Loss of DPP6 is known to cause neuronal hyperexcitability and behavioral alterations in Dpp6-KO mice. Taken together, the results of our genomic, genetic, expression and modeling analyses, provided direct evidence supporting the involvement of DPP6 loss in dementia. We propose that loss of function variants have a higher penetrance and disease impact, whereas the missense variants have a variable risk contribution to disease that can vary from high to low penetrance. Our findings of DPP6, as novel gene in dementia, strengthen the involvement of neuronal hyperexcitability and alteration in the homeostasis of neuronal firing as a disease mechanism to further investigate.
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Inversión Cromosómica , Demencia/genética , Dipeptidil-Peptidasas y Tripeptidil-Peptidasas/deficiencia , Mutación , Proteínas del Tejido Nervioso/deficiencia , Enfermedades Neurodegenerativas/genética , Neuronas/fisiología , Canales de Potasio/deficiencia , Potenciales de Acción/fisiología , Adulto , Anciano , Cromosomas Humanos Par 7/genética , Demencia/fisiopatología , Dipeptidil-Peptidasas y Tripeptidil-Peptidasas/genética , Dipeptidil-Peptidasas y Tripeptidil-Peptidasas/fisiología , Femenino , Genes Dominantes , Homeostasis , Humanos , Masculino , Persona de Mediana Edad , Proteínas del Tejido Nervioso/genética , Proteínas del Tejido Nervioso/fisiología , Enfermedades Neurodegenerativas/fisiopatología , Linaje , Penetrancia , Polimorfismo de Nucleótido Simple , Canales de Potasio/genética , Canales de Potasio/fisiología , Estabilidad Proteica , Transporte de Proteínas , Transmisión Sináptica , Secuenciación Completa del GenomaAsunto(s)
Enfermedad de Alzheimer , Apolipoproteína E4 , Humanos , Apolipoproteína E4/genética , Enfermedad de Alzheimer/genética , Apolipoproteínas E/genética , Proteínas Nucleares/genética , Proteínas Supresoras de Tumor/genética , Proteínas Adaptadoras Transductoras de Señales/genética , Metilasas de Modificación del ADN , Enzimas Reparadoras del ADNRESUMEN
INTRODUCTION: We investigated relations between amyloid-ß (Aß) status, apolipoprotein E (APOE) ε4, and cognition, with cerebrospinal fluid markers of neurogranin (Ng), neurofilament light (NFL), YKL-40, and total tau (T-tau). METHODS: We included 770 individuals with normal cognition, mild cognitive impairment, and Alzheimer's disease (AD)-type dementia from the EMIF-AD Multimodal Biomarker Discovery study. We tested the association of Ng, NFL, YKL-40, and T-tau with Aß status (Aß- vs. Aß+), clinical diagnosis APOE ε4 carriership, baseline cognition, and change in cognition. RESULTS: Ng and T-tau distinguished between Aß+ from Aß- individuals in each clinical group, whereas NFL and YKL-40 were associated with Aß+ in nondemented individuals only. APOE ε4 carriership did not influence NFL, Ng, and YKL-40 in Aß+ individuals. NFL was the best predictor of cognitive decline in Aß+ individuals across the cognitive spectrum. DISCUSSION: Axonal degeneration, synaptic dysfunction, astroglial activation, and altered tau metabolism are involved already in preclinical AD. NFL may be a useful prognostic marker.
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Enfermedad de Alzheimer/líquido cefalorraquídeo , Biomarcadores/líquido cefalorraquídeo , Disfunción Cognitiva/líquido cefalorraquídeo , Proteínas de Neurofilamentos/líquido cefalorraquídeo , Neurogranina/líquido cefalorraquídeo , Proteínas tau/líquido cefalorraquídeo , Anciano , Anciano de 80 o más Años , Enfermedad de Alzheimer/fisiopatología , Péptidos beta-Amiloides , Apolipoproteína E4/genética , Disfunción Cognitiva/fisiopatología , Femenino , HumanosRESUMEN
INTRODUCTION: Plasma proteins have been widely studied as candidate biomarkers to predict brain amyloid deposition to increase recruitment efficiency in secondary prevention clinical trials for Alzheimer's disease. Most such biomarker studies are targeted to specific proteins or are biased toward high abundant proteins. METHODS: 4001 plasma proteins were measured in two groups of participants (discovery group = 516, replication group = 365) selected from the European Medical Information Framework for Alzheimer's disease Multimodal Biomarker Discovery study, all of whom had measures of amyloid. RESULTS: A panel of proteins (n = 44), along with age and apolipoprotein E (APOE) ε4, predicted brain amyloid deposition with good performance in both the discovery group (area under the curve = 0.78) and the replication group (area under the curve = 0.68). Furthermore, a causal relationship between amyloid and tau was confirmed by Mendelian randomization. DISCUSSION: The results suggest that high-dimensional plasma protein testing could be a useful and reproducible approach for measuring brain amyloid deposition.
Asunto(s)
Enfermedad de Alzheimer , Amiloide/metabolismo , Biomarcadores/sangre , Encéfalo/metabolismo , Proteómica , Factores de Edad , Anciano , Enfermedad de Alzheimer/genética , Enfermedad de Alzheimer/metabolismo , Apolipoproteína E4/genética , Apolipoproteína E4/metabolismo , Europa (Continente) , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
INTRODUCTION: A critical and as-yet unmet need in Alzheimer's disease (AD) is the discovery of peripheral small molecule biomarkers. Given that brain pathology precedes clinical symptom onset, we set out to test whether metabolites in blood associated with pathology as indexed by cerebrospinal fluid (CSF) AD biomarkers. METHODS: This study analyzed 593 plasma samples selected from the European Medical Information Framework for Alzheimer's Disease Multimodal Biomarker Discovery study, of individuals who were cognitively healthy (n = 242), had mild cognitive impairment (n = 236), or had AD-type dementia (n = 115). Logistic regressions were carried out between plasma metabolites (n = 883) and CSF markers, magnetic resonance imaging, cognition, and clinical diagnosis. RESULTS: Eight metabolites were associated with amyloid ß and one with t-tau in CSF, these were primary fatty acid amides (PFAMs), lipokines, and amino acids. From these, PFAMs, glutamate, and aspartate also associated with hippocampal volume and memory. DISCUSSION: PFAMs have been found increased and associated with amyloid ß burden in CSF and clinical measures.
Asunto(s)
Péptidos beta-Amiloides , Amiloidosis/sangre , Biomarcadores , Hipocampo , Memoria/fisiología , Metabolómica , Anciano , Péptidos beta-Amiloides/sangre , Péptidos beta-Amiloides/líquido cefalorraquídeo , Amiloidosis/líquido cefalorraquídeo , Amiloidosis/metabolismo , Biomarcadores/sangre , Biomarcadores/líquido cefalorraquídeo , Encéfalo/patología , Disfunción Cognitiva/diagnóstico , Estudios de Cohortes , Femenino , Hipocampo/metabolismo , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Pruebas Neuropsicológicas , Proteínas tau/sangre , Proteínas tau/líquido cefalorraquídeoRESUMEN
Frontotemporal lobar degeneration (FTLD) is a neurodegenerative condition that predominantly affects behavior, social awareness, and language. It is characterized by extensive heterogeneity at the clinical, pathological, and genetic levels. Recognition of these levels of heterogeneity is important for proper disease management. The identification of progranulin and TDP-43 as key proteins in a significant proportion of FTLD patients has provided the impetus for a wealth of studies probing their role in neurodegeneration. This review highlights the most recent developments and future directions in this field and puts them in perspective of the novel insights into the neurodegenerative process, which have been gained from related disorders, e.g., the role of FUS in amyotrophic lateral sclerosis.