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1.
PLoS One ; 14(7): e0218111, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31283791

RESUMO

Late onset Alzheimer's disease is the most common form of dementia for which about 30 susceptibility loci have been reported. The aim of the current study is to identify novel genes associated with Alzheimer's disease using the largest up-to-date reference single nucleotide polymorphism (SNP) panel, the most accurate imputation software and a novel gene-based analysis approach which tests for patterns of association within genes, in the powerful genome-wide association dataset of the International Genomics of Alzheimer's Project Consortium, comprising over 7 million genotypes from 17,008 Alzheimer's cases and 37,154 controls. In addition to earlier reported genes, we detected three novel gene-wide significant loci PPARGC1A (p = 2.2 × 10-6), RORA (p = 7.4 × 10-7) and ZNF423 (p = 2.1 × 10-6). PPARGC1A and RORA are involved in circadian rhythm; circadian disturbances are one of the earliest symptoms of Alzheimer's disease. PPARGC1A is additionally linked to energy metabolism and the generation of amyloid beta plaques. RORA is involved in a variety of functions apart from circadian rhythm, such as cholesterol metabolism and inflammation. The ZNF423 gene resides in an Alzheimer's disease-specific protein network and is likely involved with centrosomes and DNA damage repair.

2.
Brain ; 2019 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-31216018

RESUMO

The mismatch repair gene MSH3 has been implicated as a genetic modifier of the CAG·CTG repeat expansion disorders Huntington's disease and myotonic dystrophy type 1. A recent Huntington's disease genome-wide association study found rs557874766, an imputed single nucleotide polymorphism located within a polymorphic 9 bp tandem repeat in MSH3/DHFR, as the variant most significantly associated with progression in Huntington's disease. Using Illumina sequencing in Huntington's disease and myotonic dystrophy type 1 subjects, we show that rs557874766 is an alignment artefact, the minor allele for which corresponds to a three-repeat allele in MSH3 exon 1 that is associated with a reduced rate of somatic CAG·CTG expansion (P = 0.004) and delayed disease onset (P = 0.003) in both Huntington's disease and myotonic dystrophy type 1, and slower progression (P = 3.86 × 10-7) in Huntington's disease. RNA-Seq of whole blood in the Huntington's disease subjects found that repeat variants are associated with MSH3 and DHFR expression. A transcriptome-wide association study in the Huntington's disease cohort found increased MSH3 and DHFR expression are associated with disease progression. These results suggest that variation in the MSH3 exon 1 repeat region influences somatic expansion and disease phenotype in Huntington's disease and myotonic dystrophy type 1, and suggests a common DNA repair mechanism operates in both repeat expansion diseases.

3.
Hum Mol Genet ; 2018 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-30358836

RESUMO

Huntington's disease (HD) is an inherited neurodegenerative disease caused by an expanded CAG repeat in the HTT gene. CAG repeat length explains around half of the variation in age-at-onset, but genetic variation elsewhere in the genome accounts for a significant proportion of the remainder. Genome-wide association studies have identified a bidirectional signal on chromosome 15, likely underlain by FAN1 (FANCD2 and FANCI Associated Nuclease 1), a nuclease involved in DNA interstrand cross link repair. Here we show that increased FAN1 expression is significantly associated with delayed age-at-onset and slower progression of HD suggesting FAN1 is protective in the context of an expanded HTT CAG repeat. FAN1 overexpression in human cells reduces CAG repeat expansion in exogenously expressed mutant HTT exon 1, and in patient-derived stem cells and differentiated medium spiny neurons, FAN1 knockdown increases CAG repeat expansion. The stabilising effect is FAN1 concentration and CAG repeat length dependent. We show that FAN1 binds to the expanded HTT CAG repeat DNA and its nuclease activity is not required for protection against CAG repeat expansion. These data shed new mechanistic insights into how the genetic modifiers of HD act to alter disease progression, and show that FAN1 affects somatic expansion of the CAG repeat through a nuclease-independent mechanism. This provides new avenues for therapeutic interventions in HD and potentially other triplet repeat disorders.

4.
J Huntingtons Dis ; 7(3): 209-222, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30103338

RESUMO

BACKGROUND: People with Huntington's disease (HD) have been observed to have lower rates of cancers. OBJECTIVE: To investigate the relationship between age of onset of HD, CAG repeat length, and cancer diagnosis. METHODS: Data were obtained from the European Huntington's disease network REGISTRY study for 6540 subjects. Population cancer incidence was ascertained from the GLOBOCAN database to obtain standardised incidence ratios of cancers in the REGISTRY subjects. RESULTS: 173/6528 HD REGISTRY subjects had had a cancer diagnosis. The age-standardised incidence rate of all cancers in the REGISTRY HD population was 0.26 (CI 0.22-0.30). Individual cancers showed a lower age-standardised incidence rate compared with the control population with prostate and colorectal cancers showing the lowest rates. There was no effect of CAG length on the likelihood of cancer, but a cancer diagnosis within the last year was associated with a greatly increased rate of HD onset (Hazard Ratio 18.94, p < 0.001). CONCLUSIONS: Cancer is less common than expected in the HD population, confirming previous reports. However, this does not appear to be related to CAG length in HTT. A recent diagnosis of cancer increases the risk of HD onset at any age, likely due to increased investigation following a cancer diagnosis.

5.
Neuropsychopharmacology ; 43(10): 2134-2145, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29950584

RESUMO

An enhanced understanding of the pathophysiology of depression would facilitate the discovery of new efficacious medications. To this end, we examined hippocampal transcriptional changes in rat models of disease and in humans to identify common disease signatures by using a new algorithm for signature-based clustering of expression profiles. The tool identified a transcriptomic signature comprising 70 probesets able to discriminate depression models from controls in both Flinders Sensitive Line and Learned Helplessness animals. To identify disease-relevant pathways, we constructed an expanded protein network based on signature gene products and performed functional annotation analysis. We applied the same workflow to transcriptomic profiles of depressed patients. Remarkably, a 171-probesets transcriptional signature which discriminated depressed from healthy subjects was identified. Rat and human signatures shared the SCARA5 gene, while the respective networks derived from protein-based significant interactions with signature genes contained 25 overlapping genes. The comparison between the most enriched pathways in the rat and human signature networks identified a highly significant overlap (p-value: 3.85 × 10-6) of 67 terms including ErbB, neurotrophin, FGF, IGF, and VEGF signaling, immune responses and insulin and leptin signaling. In conclusion, this study allowed the identification of a hippocampal transcriptional signature of resilient or susceptible responses in rat MDD models which overlapped with gene expression alterations observed in depressed patients. These findings are consistent with a loss of hippocampal neural plasticity mediated by altered levels of growth factors and increased inflammatory responses causing metabolic impairments as crucial factors in the pathophysiology of MDD.

6.
Methods Mol Biol ; 1780: 483-495, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29856032

RESUMO

Huntington's disease (HD) is caused by a CAG repeat expansion in the HTT gene. Repeat length can change over time, both in individual cells and between generations, and longer repeats may drive pathology. Cellular DNA repair systems have long been implicated in CAG repeat instability but recent genetic evidence from humans linking DNA repair variants to HD onset and progression has reignited interest in this area. The DNA damage response plays an essential role in maintaining genome stability, but may also license repeat expansions in the context of HD. In this chapter we summarize the methods developed to assay CAG repeat expansion/contraction in vitro and in cells, and review the DNA repair genes tested in mouse models of HD. While none of these systems is currently ideal, new technologies, such as long-read DNA sequencing, should improve the sensitivity of assays to assess the effects of DNA repair pathways in HD. Improved assays will be essential precursors to high-throughput testing of small molecules that can alter specific steps in DNA repair pathways and perhaps ameliorate expansion or enhance contraction of the HTT CAG repeat.

7.
PLoS Genet ; 14(5): e1007274, 2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29750799

RESUMO

Modifiers of Mendelian disorders can provide insights into disease mechanisms and guide therapeutic strategies. A recent genome-wide association (GWA) study discovered genetic modifiers of Huntington's disease (HD) onset in Europeans. Here, we performed whole genome sequencing and GWA analysis of a Venezuelan HD cluster whose families were crucial for the original mapping of the HD gene defect. The Venezuelan HD subjects develop motor symptoms earlier than their European counterparts, implying the potential for population-specific modifiers. The main Venezuelan HD family inherits HTT haplotype hap.03, which differs subtly at the sequence level from European HD hap.03, suggesting a different ancestral origin but not explaining the earlier age at onset in these Venezuelans. GWA analysis of the Venezuelan HD cluster suggests both population-specific and population-shared genetic modifiers. Genome-wide significant signals at 7p21.2-21.1 and suggestive association signals at 4p14 and 17q21.2 are evident only in Venezuelan HD, but genome-wide significant association signals at the established European chromosome 15 modifier locus are improved when Venezuelan HD data are included in the meta-analysis. Venezuelan-specific association signals on chromosome 7 center on SOSTDC1, which encodes a bone morphogenetic protein antagonist. The corresponding SNPs are associated with reduced expression of SOSTDC1 in non-Venezuelan tissue samples, suggesting that interaction of reduced SOSTDC1 expression with a population-specific genetic or environmental factor may be responsible for modification of HD onset in Venezuela. Detection of population-specific modification in Venezuelan HD supports the value of distinct disease populations in revealing novel aspects of a disease and population-relevant therapeutic strategies.


Assuntos
Genes Modificadores/genética , Estudo de Associação Genômica Ampla/métodos , Doença de Huntington/genética , Sequenciamento Completo do Genoma/métodos , Idade de Início , Saúde da Família , Feminino , Interação Gene-Ambiente , Genética Populacional , Haplótipos , Humanos , Proteína Huntingtina/genética , Masculino , Polimorfismo de Nucleotídeo Único , Proteínas/genética , Venezuela
8.
Dis Model Mech ; 11(1)2018 01 30.
Artigo em Inglês | MEDLINE | ID: mdl-29419417

RESUMO

Diseases such as Huntington's disease and certain spinocerebellar ataxias are caused by the expansion of genomic cytosine-adenine-guanine (CAG) trinucleotide repeats beyond a specific threshold. These diseases are all characterised by neurological symptoms and central neurodegeneration, but our understanding of how expanded repeats drive neuronal loss is incomplete. Recent human genetic evidence implicates DNA repair pathways, especially mismatch repair, in modifying the onset and progression of CAG repeat diseases. Repair pathways might operate directly on repeat sequences by licensing or inhibiting repeat expansion in neurons. Alternatively, or in addition, because many of the genes containing pathogenic CAG repeats encode proteins that themselves have roles in the DNA damage response, it is possible that repeat expansions impair specific DNA repair pathways. DNA damage could then accrue in neurons, leading to further expansion at repeat loci, thus setting up a vicious cycle of pathology. In this review, we consider DNA damage and repair pathways in postmitotic neurons in the context of disease-causing CAG repeats. Investigating and understanding these pathways, which are clearly relevant in promoting and ameliorating disease in humans, is a research priority, as they are known to modify disease and therefore constitute prevalidated drug targets.


Assuntos
Dano ao DNA/genética , Reparo do DNA/genética , Expansão das Repetições de Trinucleotídeos/genética , Animais , Genoma , Humanos , Modelos Biológicos
9.
Hum Mol Genet ; 26(R2): R83-R90, 2017 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-28977442

RESUMO

In the decades since the genes and mutations associated with the commoner Mendelian disorders were first discovered, technological advances in genetic analysis have made finding genomic variation a much less onerous task. Recently, the global efforts to collect subjects with Mendelian disorders, to better define the disorders and to empower appropriate clinical trials, along with improved genetic technologies, have allowed the identification of genetic variation that does not cause disease, but substantially modifies disease presentation. The advantage of this is it identifies biological pathways and molecules, that, if modified in people, might alter disease presentation. In Huntington's disease (HD), caused by an expanded CAG repeat tract in HTT, genetic variation has been uncovered that is associated with change in the onset or progression of disease. Some of this variation lies in genes that are part of the DNA damage response, previously suggested to be important in modulating expansion of the repeat tract in germline and somatic cells. The genetic evidence implicates a DNA damage response-related pathway in modulating the pathogenicity of the repeat tracts in HD, and possibly, in other trinucleotide repeat disorders. These findings offer new targets for drug development in these currently intractable disorders.


Assuntos
Proteína Huntingtina/genética , Doença de Huntington/genética , Genes Modificadores , Predisposição Genética para Doença/genética , Estudo de Associação Genômica Ampla/métodos , Humanos , Proteína Huntingtina/metabolismo , Mutação/genética , Expansão das Repetições de Trinucleotídeos/genética , Repetições de Trinucleotídeos/genética
10.
Hum Mol Genet ; 26(19): 3859-3867, 2017 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-28934397

RESUMO

Huntington's disease (HD) is a dominantly inherited neurodegenerative disease caused by an expanded CAG repeat in HTT. Many clinical characteristics of HD such as age at motor onset are determined largely by the size of HTT CAG repeat. However, emerging evidence strongly supports a role for other genetic factors in modifying the disease pathogenesis driven by mutant huntingtin. A recent genome-wide association analysis to discover genetic modifiers of HD onset age provided initial evidence for modifier loci on chromosomes 8 and 15 and suggestive evidence for a locus on chromosome 3. Here, genotyping of candidate single nucleotide polymorphisms in a cohort of 3,314 additional HD subjects yields independent confirmation of the former two loci and moves the third to genome-wide significance at MLH1, a locus whose mouse orthologue modifies CAG length-dependent phenotypes in a Htt-knock-in mouse model of HD. Both quantitative and dichotomous association analyses implicate a functional variant on ∼32% of chromosomes with the beneficial modifier effect that delays HD motor onset by 0.7 years/allele. Genomic DNA capture and sequencing of a modifier haplotype localize the functional variation to a 78 kb region spanning the 3'end of MLH1 and the 5'end of the neighboring LRRFIP2, and marked by an isoleucine-valine missense variant in MLH1. Analysis of expression Quantitative Trait Loci (eQTLs) provides modest support for altered regulation of MLH1 and LRRFIP2, raising the possibility that the modifier affects regulation of both genes. Finally, polygenic modification score and heritability analyses suggest the existence of additional genetic modifiers, supporting expanded, comprehensive genetic analysis of larger HD datasets.


Assuntos
Proteína Huntingtina/genética , Proteína 1 Homóloga a MutL/genética , Alelos , Animais , Cromossomos Humanos Par 15 , Cromossomos Humanos Par 8 , Modelos Animais de Doenças , Genes Modificadores/genética , Estudo de Associação Genômica Ampla , Genótipo , Humanos , Doença de Huntington/genética , Doença de Huntington/metabolismo , Camundongos , Proteína 1 Homóloga a MutL/metabolismo , Fenótipo , Polimorfismo de Nucleotídeo Único/genética , Repetições de Trinucleotídeos
11.
Eur J Hum Genet ; 25(11): 1202-1209, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28832564

RESUMO

Huntington's disease (HD) is an autosomal dominant neurodegenerative disease caused by expansion of a CAG trinucleotide repeat in HTT, resulting in an extended polyglutamine tract in huntingtin. We and others have previously determined that the HD-causing expansion occurs on multiple different haplotype backbones, reflecting more than one ancestral origin of the same type of mutation. In view of the therapeutic potential of mutant allele-specific gene silencing, we have compared and integrated two major systems of HTT haplotype definition, combining data from 74 sequence variants to identify the most frequent disease-associated and control chromosome backbones and revealing that there is potential for additional resolution of HD haplotypes. We have used the large collection of 4078 heterozygous HD subjects analyzed in our recent genome-wide association study of HD age at onset to estimate the frequency of these haplotypes in European subjects, finding that common genetic variation at HTT can distinguish the normal and CAG-expanded chromosomes for more than 95% of European HD individuals. As a resource for the HD research community, we have also determined the haplotypes present in a series of publicly available HD subject-derived fibroblasts, induced pluripotent cells, and embryonic stem cells in order to facilitate efforts to develop inclusive methods of allele-specific HTT silencing applicable to most HD patients. Our data providing genetic guidance for therapeutic gene-based targeting will significantly contribute to the developments of rational treatments and implementation of precision medicine in HD.


Assuntos
Haplótipos , Doença de Huntington/genética , Linhagem Celular , Células-Tronco Embrionárias/metabolismo , Fibroblastos/metabolismo , Frequência do Gene , Heterozigoto , Humanos , Proteína Huntingtina/genética , Células-Tronco Pluripotentes Induzidas/metabolismo , Polimorfismo Genético
13.
Lancet Neurol ; 16(9): 701-711, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28642124

RESUMO

BACKGROUND: Huntington's disease is caused by a CAG repeat expansion in the huntingtin gene, HTT. Age at onset has been used as a quantitative phenotype in genetic analysis looking for Huntington's disease modifiers, but is hard to define and not always available. Therefore, we aimed to generate a novel measure of disease progression and to identify genetic markers associated with this progression measure. METHODS: We generated a progression score on the basis of principal component analysis of prospectively acquired longitudinal changes in motor, cognitive, and imaging measures in the 218 indivduals in the TRACK-HD cohort of Huntington's disease gene mutation carriers (data collected 2008-11). We generated a parallel progression score using data from 1773 previously genotyped participants from the European Huntington's Disease Network REGISTRY study of Huntington's disease mutation carriers (data collected 2003-13). We did a genome-wide association analyses in terms of progression for 216 TRACK-HD participants and 1773 REGISTRY participants, then a meta-analysis of these results was undertaken. FINDINGS: Longitudinal motor, cognitive, and imaging scores were correlated with each other in TRACK-HD participants, justifying use of a single, cross-domain measure of disease progression in both studies. The TRACK-HD and REGISTRY progression measures were correlated with each other (r=0·674), and with age at onset (TRACK-HD, r=0·315; REGISTRY, r=0·234). The meta-analysis of progression in TRACK-HD and REGISTRY gave a genome-wide significant signal (p=1·12 × 10-10) on chromosome 5 spanning three genes: MSH3, DHFR, and MTRNR2L2. The genes in this locus were associated with progression in TRACK-HD (MSH3 p=2·94 × 10-8DHFR p=8·37 × 10-7 MTRNR2L2 p=2·15 × 10-9) and to a lesser extent in REGISTRY (MSH3 p=9·36 × 10-4DHFR p=8·45 × 10-4MTRNR2L2 p=1·20 × 10-3). The lead single nucleotide polymorphism (SNP) in TRACK-HD (rs557874766) was genome-wide significant in the meta-analysis (p=1·58 × 10-8), and encodes an aminoacid change (Pro67Ala) in MSH3. In TRACK-HD, each copy of the minor allele at this SNP was associated with a 0·4 units per year (95% CI 0·16-0·66) reduction in the rate of change of the Unified Huntington's Disease Rating Scale (UHDRS) Total Motor Score, and a reduction of 0·12 units per year (95% CI 0·06-0·18) in the rate of change of UHDRS Total Functional Capacity score. These associations remained significant after adjusting for age of onset. INTERPRETATION: The multidomain progression measure in TRACK-HD was associated with a functional variant that was genome-wide significant in our meta-analysis. The association in only 216 participants implies that the progression measure is a sensitive reflection of disease burden, that the effect size at this locus is large, or both. Knockout of Msh3 reduces somatic expansion in Huntington's disease mouse models, suggesting this mechanism as an area for future therapeutic investigation. FUNDING: The European Commission FP7 NeurOmics project; CHDI Foundation; the Medical Research Council UK; the Brain Research Trust; and the Guarantors of Brain.


Assuntos
Proteínas de Ligação a DNA/genética , Progressão da Doença , Estudo de Associação Genômica Ampla/métodos , Doença de Huntington/genética , Doença de Huntington/fisiopatologia , Sistema de Registros , Índice de Gravidade de Doença , Adulto , Humanos , Estudos Longitudinais , Proteína 3 Homóloga a MutS , Análise de Componente Principal
14.
Sci Rep ; 7: 44849, 2017 03 21.
Artigo em Inglês | MEDLINE | ID: mdl-28322270

RESUMO

There is widespread transcriptional dysregulation in Huntington's disease (HD) brain, but analysis is inevitably limited by advanced disease and postmortem changes. However, mutant HTT is ubiquitously expressed and acts systemically, meaning blood, which is readily available and contains cells that are dysfunctional in HD, could act as a surrogate for brain tissue. We conducted an RNA-Seq transcriptomic analysis using whole blood from two HD cohorts, and performed gene set enrichment analysis using public databases and weighted correlation network analysis modules from HD and control brain datasets. We identified dysregulated gene sets in blood that replicated in the independent cohorts, correlated with disease severity, corresponded to the most significantly dysregulated modules in the HD caudate, the most prominently affected brain region, and significantly overlapped with the transcriptional signature of HD myeloid cells. High-throughput sequencing technologies and use of gene sets likely surmounted the limitations of previously inconsistent HD blood expression studies. Our results suggest transcription is disrupted in peripheral cells in HD through mechanisms that parallel those in brain. Immune upregulation in HD overlapped with Alzheimer's disease, suggesting a common pathogenic mechanism involving macrophage phagocytosis and microglial synaptic pruning, and raises the potential for shared therapeutic approaches.


Assuntos
Doença de Alzheimer/etiologia , Encéfalo/metabolismo , Regulação da Expressão Gênica , Doença de Huntington/etiologia , Imunidade/genética , Transcriptoma , Adulto , Idoso , Doença de Alzheimer/sangue , Doença de Alzheimer/diagnóstico , Doença de Alzheimer/metabolismo , Biomarcadores , Estudos de Casos e Controles , Feminino , Perfilação da Expressão Gênica , Redes Reguladoras de Genes , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Doença de Huntington/sangue , Doença de Huntington/diagnóstico , Doença de Huntington/metabolismo , Masculino , Pessoa de Meia-Idade , Células Mieloides/imunologia , Células Mieloides/metabolismo , Córtex Pré-Frontal/metabolismo , Transdução de Sinais , Adulto Jovem
15.
Lancet Neurol ; 16(1): 88-96, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27979358

RESUMO

BACKGROUND: Inherited diseases caused by unstable repeated DNA sequences are rare, but together represent a substantial cause of morbidity. Trinucleotide repeat disorders are severe, usually life-shortening, neurological disorders caused by nucleotide expansions, and most have no disease-modifying treatments. Longer repeat expansions are associated with genetic anticipation (ie, earlier disease onset in successive generations), although the differences in age at onset are not entirely accounted for by repeat length. Such phenotypic variation within disorders implies the existence of additional modifying factors in pathways that can potentially be modulated to treat disease. RECENT DEVELOPMENTS: A genome-wide association study detected genetic modifiers of age at onset in Huntington's disease. Similar findings were seen in the spinocerebellar ataxias, indicating an association between DNA damage-response and repair pathways and the age at onset of disease. These studies also suggest that a common genetic mechanism modulates age at onset across polyglutamine diseases and could extend to other repeat expansion disorders. Genetic defects in DNA repair underlie other neurodegenerative disorders (eg, ataxia-telangiectasia), and DNA double-strand breaks are crucial to the modulation of early gene expression, which provides a mechanistic link between DNA repair and neurodegeneration. Mismatch and base-excision repair are important in the somatic expansion of repeated sequences in mouse models of trinucleotide repeat disorders, and somatic expansion of the expanded CAG tract in HTT correlates with age at onset of Huntington's disease and other trinucleotide repeat disorders. WHERE NEXT?: To understand the common genetic architecture of trinucleotide repeat disorders and any further genetic susceptibilities in individual disorders, genetic analysis with increased numbers of variants and sample sizes is needed, followed by sequencing approaches to define the phenotype-modifying variants. The findings must then be translated into cell biology analyses to elucidate the mechanisms through which the genetic variants operate. Genes that have roles in the DNA damage response could underpin a common DNA repeat-based mechanism and provide new therapeutic targets (and hence therapeutics) in multiple trinucleotide repeat disorders.


Assuntos
Reparo do DNA/genética , Proteína Huntingtina/genética , Doença de Huntington/genética , Expansão das Repetições de Trinucleotídeos/genética , Estudo de Associação Genômica Ampla , Humanos
16.
J Alzheimers Dis ; 56(1): 25-36, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-27911318

RESUMO

Plasma biomarkers to aid the early diagnosis of Alzheimer's disease (AD) or to monitor disease progression have long been sought and continue to be widely studied. Biomarkers that correlate with AD polygenic risk score, a measure of the polygenic architecture of the disease and highly predictive of AD status, would be excellent candidates. Therefore, we undertook a preliminary study to assess the association of plasma inflammatory biomarkers with an overall AD polygenic risk score as well as with an inflammation-specific AD polygenic risk score in a sample set of 93 AD cases. We measured five complement biomarkers [complement receptor 1 (CR1), clusterin, complement component 9 (C9), C1 inhibitor (C1inh), terminal complement complex (TCC)] and the benchmark inflammatory marker C-reactive protein (CRP). Plasma clusterin level showed an association with overall AD polygenic risk score, while clusterin, C1inh, and CRP levels each displayed some association with the inflammatory-specific AD polygenic risk score. The results suggest that elevated plasma levels of inflammatory biomarkers, including complement proteins, associate with polygenic risk scores in AD, further strengthening the link between genetic and biomarker disease predictors and indicating a potential role for these markers in disease prediction and patient stratification in AD.


Assuntos
Doença de Alzheimer/sangue , Doença de Alzheimer/complicações , Biomarcadores/sangue , Citocinas/sangue , Inflamação/etiologia , Doença de Alzheimer/genética , Proteína C-Reativa/metabolismo , Clusterina/sangue , Proteína Inibidora do Complemento C1/metabolismo , Progressão da Doença , Feminino , Humanos , Inflamação/sangue , Masculino , Herança Multifatorial/genética , Testes Neuropsicológicos , Receptores de Complemento/sangue , Fatores de Risco , Estatística como Assunto , Estatísticas não Paramétricas
17.
PLoS One ; 11(10): e0165069, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27736977

RESUMO

[This corrects the article DOI: 10.1371/journal.pone.0144864.].

18.
BMC Neurosci ; 17(1): 50, 2016 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-27430330

RESUMO

BACKGROUND: Polymorphisms in the gene for phosphatidylinositol binding clathrin assembly protein (PICALM), an endocytic-related protein, are associated with a small, increased risk of developing Alzheimer's disease (AD), strongly suggesting that changes in endocytosis are involved in the aetiology of the disease. We have investigated the involvement of PICALM in the processing of amyloid precursor protein (APP) to understand how PICALM could be linked to the development of AD. We used siRNA to deplete levels of PICALM, its isoforms and clathrin heavy chain in the human brain-derived H4 neuroglioma cell line that expresses endogenous levels of APP. We then used Western blotting, ELISA and immunohistochemistry to detect intra- and extracellular protein levels of endocytic-related proteins, APP and APP metabolites including ß-amyloid (Aß). Levels of functional endocytosis were quantified using ALEXA 488-conjugated transferrin and flow cytometry as a marker of clathrin-mediated endocytosis (CME). RESULTS: Following depletion of all the isoforms of PICALM by siRNA in H4 cells, levels of intracellular APP, intracellular ß-C-terminal fragment (ß-CTF) and secreted sAPPß (APP fragments produced by ß-secretase cleavage) were significantly reduced but Aß40 was not affected. Functional endocytosis was significantly reduced after both PICALM and clathrin depletion, highlighting the importance of PICALM in this process. However, depletion of clathrin did not affect APP but did reduce ß-CTF levels. PICALM depletion altered the intracellular distribution of clathrin while clathrin reduction affected the subcellular pattern of PICALM labelling. Both PICALM and clathrin depletion reduced the expression of BACE1 mRNA and PICALM siRNA reduced protein levels. Individual depletion of PICALM isoforms 1 and 2 did not affect APP levels while clathrin depletion had a differential effect on the isoforms, increasing isoform 1 while decreasing isoform 2 expression. CONCLUSIONS: The depletion of PICALM in brain-derived cells has significant effects on the processing of APP, probably by reducing CME. In particular, it affects the production of ß-CTF which is increasingly considered to be an important mediator in AD independent of Aß. Thus a decrease in PICALM expression in the brain could be beneficial to slow or prevent the development of AD.


Assuntos
Secretases da Proteína Precursora do Amiloide/metabolismo , Endocitose/fisiologia , Proteínas Monoméricas de Montagem de Clatrina/deficiência , Doença de Alzheimer/metabolismo , Peptídeos beta-Amiloides/metabolismo , Precursor de Proteína beta-Amiloide/metabolismo , Western Blotting , Encéfalo/metabolismo , Linhagem Celular Tumoral , Cadeias Pesadas de Clatrina/genética , Cadeias Pesadas de Clatrina/metabolismo , Ensaio de Imunoadsorção Enzimática , Citometria de Fluxo , Humanos , Imuno-Histoquímica , Proteínas Monoméricas de Montagem de Clatrina/genética , Fragmentos de Peptídeos/metabolismo , Isoformas de Proteínas/deficiência , Isoformas de Proteínas/genética , RNA Mensageiro/metabolismo , RNA Interferente Pequeno , Transferrina/metabolismo
19.
PLoS One ; 11(5): e0155834, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27196694

RESUMO

Huntington's disease (HD) cellular pathology is characterised by the aggregation of mutant huntingtin (mHTT) protein into inclusion bodies. The present paper compared the sensitivity of five widely used mHTT antibodies (S830; MW8; EM48; 1C2; ubiquitin) against mice from five commonly used HD mouse models (R6/1; YAC128; HdhQ92; B6 HdhQ150; B6 x129/Ola HdhQ150) at two ages to determine: the most sensitive antibodies for each model; whether mHTT antibody binding differed depending on aggregation stage (diffuse versus frank inclusion); the role of ubiquitin during aggregation as the ubiquitin proteosome system has been implicated in disease development. The models demonstrated unique profiles of antibody binding even when the models varied only by background strain (HdhQ150). MW8 was highly sensitive for detecting frank inclusions in all lines whereas EM48, ubiquitin and 1C2 demonstrated consistent staining in all models irrespective of age or form of mHTT. MW8 and S830 were the most sensitive antibodies with 1C2 the least. Ubiquitin levels were stable for each model regardless of age. Ubiquitin was particularly sensitive in young YAC128 mice that demonstrate an absence of inclusions until ~12 months of age suggesting high affinity to mHTT in its diffuse form. The data indicate that generalisations across models regarding the quantification of aggregations may not be valid and that mHTT antibody binding is unique to the mouse model and sensitive to changes in inclusion development.


Assuntos
Proteína Huntingtina/metabolismo , Doença de Huntington/metabolismo , Ubiquitina/metabolismo , Animais , Anticorpos/química , Encéfalo/metabolismo , Modelos Animais de Doenças , Genótipo , Proteína Huntingtina/imunologia , Imuno-Histoquímica , Corpos de Inclusão/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Ligação Proteica , Reprodutibilidade dos Testes
20.
Hum Mol Genet ; 25(14): 2893-2904, 2016 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-27170315

RESUMO

Innate immune activation beyond the central nervous system is emerging as a vital component of the pathogenesis of neurodegeneration. Huntington's disease (HD) is a fatal neurodegenerative disorder caused by a CAG repeat expansion in the huntingtin gene. The systemic innate immune system is thought to act as a modifier of disease progression; however, the molecular mechanisms remain only partially understood. Here we use RNA-sequencing to perform whole transcriptome analysis of primary monocytes from thirty manifest HD patients and thirty-three control subjects, cultured with and without a proinflammatory stimulus. In contrast with previous studies that have required stimulation to elicit phenotypic abnormalities, we demonstrate significant transcriptional differences in HD monocytes in their basal, unstimulated state. This includes previously undetected increased resting expression of genes encoding numerous proinflammatory cytokines, such as IL6 Further pathway analysis revealed widespread resting enrichment of proinflammatory functional gene sets, while upstream regulator analysis coupled with Western blotting suggests that abnormal basal activation of the NFĸB pathway plays a key role in mediating these transcriptional changes. That HD myeloid cells have a proinflammatory phenotype in the absence of stimulation is consistent with a priming effect of mutant huntingtin, whereby basal dysfunction leads to an exaggerated inflammatory response once a stimulus is encountered. These data advance our understanding of mutant huntingtin pathogenesis, establish resting myeloid cells as a key source of HD immune dysfunction, and further demonstrate the importance of systemic immunity in the potential treatment of HD and the wider study of neurodegeneration.


Assuntos
Proteína Huntingtina/genética , Doença de Huntington/genética , Imunidade Inata/genética , Inflamação/genética , Ativação Transcricional/genética , Perfilação da Expressão Gênica , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Proteína Huntingtina/biossíntese , Doença de Huntington/patologia , Inflamação/patologia , Interleucina-6/genética , Células Mieloides/metabolismo , Células Mieloides/patologia , Proteínas do Tecido Nervoso/biossíntese , Proteínas do Tecido Nervoso/genética , Transdução de Sinais , Expansão das Repetições de Trinucleotídeos/genética
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