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1.
Genome Res ; 31(6): 1069-1081, 2021 06.
Article in English | MEDLINE | ID: mdl-34011578

ABSTRACT

Single-cell RNA sequencing (scRNA-seq) is a widely used method for identifying cell types and trajectories in biologically heterogeneous samples, but it is limited in its detection and quantification of lowly expressed genes. This results in missing important biological signals, such as the expression of key transcription factors (TFs) driving cellular differentiation. We show that targeted sequencing of ∼1000 TFs (scCapture-seq) in iPSC-derived neuronal cultures greatly improves the biological information garnered from scRNA-seq. Increased TF resolution enhanced cell type identification, developmental trajectories, and gene regulatory networks. This allowed us to resolve differences among neuronal populations, which were generated in two different laboratories using the same differentiation protocol. ScCapture-seq improved TF-gene regulatory network inference and thus identified divergent patterns of neurogenesis into either excitatory cortical neurons or inhibitory interneurons. Furthermore, scCapture-seq revealed a role for of retinoic acid signaling in the developmental divergence between these different neuronal populations. Our results show that TF targeting improves the characterization of human cellular models and allows identification of the essential differences between cellular populations, which would otherwise be missed in traditional scRNA-seq. scCapture-seq TF targeting represents a cost-effective enhancement of scRNA-seq, which could be broadly applied to improve scRNA-seq resolution.


Subject(s)
Induced Pluripotent Stem Cells , Single-Cell Analysis , Gene Expression Profiling/methods , Gene Regulatory Networks , Humans , Induced Pluripotent Stem Cells/metabolism , Sequence Analysis, RNA/methods , Single-Cell Analysis/methods , Transcription Factors/genetics , Transcription Factors/metabolism
2.
Int J Mol Sci ; 24(9)2023 May 01.
Article in English | MEDLINE | ID: mdl-37175835

ABSTRACT

Inhibitory GABAergic interneurons originate in the embryonic medial ganglionic eminence (MGE) and control network activity in the neocortex. Dysfunction of these cells is believed to lead to runaway excitation underlying seizure-based neurological disorders such as epilepsy, autism, and schizophrenia. Despite their importance in heath and disease, our knowledge about the development of this diverse neuronal population remains incomplete. Here we conducted single-cell RNA sequencing (scRNA-seq) of human foetal MGE from 10 to 15 weeks post conception. These MGE tissues are composed of largely cycling progenitors and immature post-mitotic interneurons with characteristic regional marker expression. Analysis of integrated human and mouse MGE data revealed species-conserved transcriptomic profiles and regulatory programs. Moreover, we identified novel candidate transcription regulators for human interneuron differentiation. These findings provide a framework for in vitro modelling of interneuron development and a strategy for potentially enhancing interneuron production from human pluripotent stem cells.


Subject(s)
Neocortex , Transcriptome , Humans , Mice , Animals , Interneurons/metabolism , Cell Differentiation/genetics , GABAergic Neurons/metabolism
3.
Hum Mol Genet ; 28(12): 2001-2013, 2019 06 15.
Article in English | MEDLINE | ID: mdl-30753527

ABSTRACT

Parkinson's disease (PD) is the second most common neurodegenerative disorder and a central role for α-synuclein (αSyn; SNCA) in disease aetiology has been proposed based on genetics and neuropathology. To better understand the pathological mechanisms of αSyn, we generated induced pluripotent stem cells (iPSCs) from healthy individuals and PD patients carrying the A53T SNCA mutation or a triplication of the SNCA locus and differentiated them into dopaminergic neurons (DAns). iPSC-derived DAn from PD patients carrying either mutation showed increased intracellular αSyn accumulation, and DAns from patients carrying the SNCA triplication displayed oligomeric αSyn pathology and elevated αSyn extracellular release. Transcriptomic analysis of purified DAns revealed perturbations in expression of genes linked to mitochondrial function, consistent with observed reduction in mitochondrial respiration, impairment in mitochondrial membrane potential, aberrant mitochondrial morphology and decreased levels of phosphorylated DRP1Ser616. Parkinson's iPSC-derived DAns showed increased endoplasmic reticulum stress and impairments in cholesterol and lipid homeostasis. Together, these data show a correlation between αSyn cellular pathology and deficits in metabolic and cellular bioenergetics in the pathology of PD.


Subject(s)
Dopaminergic Neurons/metabolism , Induced Pluripotent Stem Cells/metabolism , Mitochondria/metabolism , Parkinson Disease/genetics , alpha-Synuclein/genetics , Cell Differentiation , Dynamins/metabolism , Endoplasmic Reticulum Stress/genetics , Energy Metabolism/genetics , Humans , Lipid Metabolism/genetics , Membrane Potential, Mitochondrial , Mitochondria/ultrastructure , Mutation , Parkinson Disease/metabolism , RNA-Seq , Synucleinopathies/metabolism , alpha-Synuclein/metabolism
4.
Ann Neurol ; 87(6): 853-868, 2020 06.
Article in English | MEDLINE | ID: mdl-32167609

ABSTRACT

OBJECTIVE: Neuronal loss in the substantia nigra pars compacta (SNpc) in Parkinson disease (PD) is not uniform, as dopamine neurons from the ventral tier are lost more rapidly than those of the dorsal tier. Identifying the intrinsic differences that account for this differential vulnerability may provide a key for developing new treatments for PD. METHODS: Here, we compared the RNA-sequenced transcriptomes of ~100 laser captured microdissected SNpc neurons from each tier from 7 healthy controls. RESULTS: Expression levels of dopaminergic markers were similar across the tiers, whereas markers specific to the neighboring ventral tegmental area were virtually undetected. After accounting for unwanted sources of variation, we identified 106 differentially expressed genes (DEGs) between the SNpc tiers. The genes higher in the dorsal/resistant SNpc tier neurons displayed coordinated patterns of expression across the human brain, their protein products had more interactions than expected by chance, and they demonstrated evidence of functional convergence. No significant shared functionality was found for genes higher in the ventral/vulnerable SNpc tier. Surprisingly but importantly, none of the identified DEGs was among the familial PD genes or genome-wide associated loci. Finally, we found some DEGs in opposite tier orientation between human and analogous mouse populations. INTERPRETATION: Our results highlight functional enrichments of vesicular trafficking, ion transport/homeostasis and oxidative stress genes showing higher expression in the resistant neurons of the SNpc dorsal tier. Furthermore, the comparison of gene expression variation in human and mouse SNpc populations strongly argues for the need of human-focused omics studies. ANN NEUROL 2020;87:853-868.


Subject(s)
Dopaminergic Neurons/pathology , Mesencephalon/pathology , Parkinson Disease/genetics , Parkinson Disease/pathology , Transcriptome , Animals , Gene Expression Regulation/genetics , Genome-Wide Association Study , Healthy Volunteers , Humans , Mice , RNA/genetics , Substantia Nigra/pathology , Ventral Tegmental Area/pathology
6.
Mol Psychiatry ; 25(11): 3091-3099, 2020 11.
Article in English | MEDLINE | ID: mdl-31168069

ABSTRACT

Genome-wide association studies (GWAS) of psychiatric phenotypes have tended to focus on categorical diagnoses, but to understand the biology of mental illness it may be more useful to study traits which cut across traditional boundaries. Here, we report the results of a GWAS of mood instability as a trait in a large population cohort (UK Biobank, n = 363,705). We also assess the clinical and biological relevance of the findings, including whether genetic associations show enrichment for nervous system pathways. Forty six unique loci associated with mood instability were identified with a SNP heritability estimate of 9%. Linkage Disequilibrium Score Regression (LDSR) analyses identified genetic correlations with Major Depressive Disorder (MDD), Bipolar Disorder (BD), Schizophrenia, anxiety, and Post Traumatic Stress Disorder (PTSD). Gene-level and gene set analyses identified 244 significant genes and 6 enriched gene sets. Tissue expression analysis of the SNP-level data found enrichment in multiple brain regions, and eQTL analyses highlighted an inversion on chromosome 17 plus two brain-specific eQTLs. In addition, we used a Phenotype Linkage Network (PLN) analysis and community analysis to assess for enrichment of nervous system gene sets using mouse orthologue databases. The PLN analysis found enrichment in nervous system PLNs for a community containing serotonin and melatonin receptors. In summary, this work has identified novel loci, tissues and gene sets contributing to mood instability. These findings may be relevant for the identification of novel trans-diagnostic drug targets and could help to inform future stratified medicine innovations in mental health.


Subject(s)
Affect , Databases, Factual , Gene Expression , Genetic Predisposition to Disease/genetics , Genomics , Mental Disorders/genetics , Mood Disorders/genetics , Adult , Aged , Animals , Female , Genome-Wide Association Study , Humans , Male , Mice , Middle Aged , Polymorphism, Single Nucleotide/genetics , United Kingdom
7.
Brain ; 143(9): 2771-2787, 2020 09 01.
Article in English | MEDLINE | ID: mdl-32889528

ABSTRACT

Dystonia is a neurological disorder characterized by sustained or intermittent muscle contractions causing abnormal movements and postures, often occurring in absence of any structural brain abnormality. Psychiatric comorbidities, including anxiety, depression, obsessive-compulsive disorder and schizophrenia, are frequent in patients with dystonia. While mutations in a fast-growing number of genes have been linked to Mendelian forms of dystonia, the cellular, anatomical, and molecular basis remains unknown for most genetic forms of dystonia, as does its genetic and biological relationship to neuropsychiatric disorders. Here we applied an unbiased systems-biology approach to explore the cellular specificity of all currently known dystonia-associated genes, predict their functional relationships, and test whether dystonia and neuropsychiatric disorders share a genetic relationship. To determine the cellular specificity of dystonia-associated genes in the brain, single-nuclear transcriptomic data derived from mouse brain was used together with expression-weighted cell-type enrichment. To identify functional relationships among dystonia-associated genes, we determined the enrichment of these genes in co-expression networks constructed from 10 human brain regions. Stratified linkage-disequilibrium score regression was used to test whether co-expression modules enriched for dystonia-associated genes significantly contribute to the heritability of anxiety, major depressive disorder, obsessive-compulsive disorder, schizophrenia, and Parkinson's disease. Dystonia-associated genes were significantly enriched in adult nigral dopaminergic neurons and striatal medium spiny neurons. Furthermore, 4 of 220 gene co-expression modules tested were significantly enriched for the dystonia-associated genes. The identified modules were derived from the substantia nigra, putamen, frontal cortex, and white matter, and were all significantly enriched for genes associated with synaptic function. Finally, we demonstrate significant enrichments of the heritability of major depressive disorder, obsessive-compulsive disorder and schizophrenia within the putamen and white matter modules, and a significant enrichment of the heritability of Parkinson's disease within the substantia nigra module. In conclusion, multiple dystonia-associated genes interact and contribute to pathogenesis likely through dysregulation of synaptic signalling in striatal medium spiny neurons, adult nigral dopaminergic neurons and frontal cortical neurons. Furthermore, the enrichment of the heritability of psychiatric disorders in the co-expression modules enriched for dystonia-associated genes indicates that psychiatric symptoms associated with dystonia are likely to be intrinsic to its pathophysiology.


Subject(s)
Dystonic Disorders/genetics , Gene Regulatory Networks/genetics , Mental Disorders/genetics , Neurons/physiology , Dystonic Disorders/diagnosis , Dystonic Disorders/epidemiology , Humans , Mental Disorders/diagnosis , Mental Disorders/epidemiology
8.
Trends Genet ; 33(4): 256-265, 2017 04.
Article in English | MEDLINE | ID: mdl-28268034

ABSTRACT

The contribution of epistasis to human disease remains unclear. However, several studies have now identified epistatic interactions between common variants that increase the risk of a neuropsychiatric disorder, while there is growing evidence that genetic interactions contribute to the pathogenicity of rare, multigenic copy-number variants (CNVs) that have been observed in patients. This review discusses the current evidence for epistatic events and genetic interactions in neuropsychiatric disorders, how paradigm shifts in the phenotypic classification of patients would empower the search for epistatic effects, and how network and cellular models might be employed to further elucidate relevant epistatic interactions.


Subject(s)
Autistic Disorder/genetics , Bipolar Disorder/genetics , Epistasis, Genetic , Schizophrenia/genetics , Autistic Disorder/pathology , Bipolar Disorder/pathology , DNA Copy Number Variations/genetics , Genotype , Humans , Phenotype , Quantitative Trait Loci/genetics , Schizophrenia/pathology
9.
Mov Disord ; 35(11): 2056-2067, 2020 11.
Article in English | MEDLINE | ID: mdl-32864809

ABSTRACT

BACKGROUND: Parkinson's disease (PD) is a neurodegenerative disease with an often complex component identifiable by genome-wide association studies. The most recent large-scale PD genome-wide association studies have identified more than 90 independent risk variants for PD risk and progression across more than 80 genomic regions. One major challenge in current genomics is the identification of the causal gene(s) and variant(s) at each genome-wide association study locus. The objective of the current study was to create a tool that would display data for relevant PD risk loci and provide guidance with the prioritization of causal genes and potential mechanisms at each locus. METHODS: We included all significant genome-wide signals from multiple recent PD genome-wide association studies including themost recent PD risk genome-wide association study, age-at-onset genome-wide association study, progression genome-wide association study, and Asian population PD risk genome-wide association study. We gathered data for all genes 1 Mb up and downstream of each variant to allow users to assess which gene(s) are most associated with the variant of interest based on a set of self-ranked criteria. Multiple databases were queried for each gene to collect additional causal data. RESULTS: We created a PD genome-wide association study browser tool (https://pdgenetics.shinyapps.io/GWASBrowser/) to assist the PD research community with the prioritization of genes for follow-up functional studies to identify potential therapeutic targets. CONCLUSIONS: Our PD genome-wide association study browser tool provides users with a useful method of identifying potential causal genes at all known PD risk loci from large-scale PD genome-wide association studies. We plan to update this tool with new relevant data as sample sizes increase and new PD risk loci are discovered. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society. This article has been contributed to by US Government employees and their work is in the public domain in the USA.


Subject(s)
Neurodegenerative Diseases , Parkinson Disease , Age of Onset , Genetic Predisposition to Disease/genetics , Genome-Wide Association Study , Humans , Parkinson Disease/genetics , Risk Factors
10.
Brain ; 142(10): 3243-3264, 2019 10 01.
Article in English | MEDLINE | ID: mdl-31504240

ABSTRACT

Neuroinflammation and microglial activation are significant processes in Alzheimer's disease pathology. Recent genome-wide association studies have highlighted multiple immune-related genes in association with Alzheimer's disease, and experimental data have demonstrated microglial proliferation as a significant component of the neuropathology. In this study, we tested the efficacy of the selective CSF1R inhibitor JNJ-40346527 (JNJ-527) in the P301S mouse tauopathy model. We first demonstrated the anti-proliferative effects of JNJ-527 on microglia in the ME7 prion model, and its impact on the inflammatory profile, and provided potential CNS biomarkers for clinical investigation with the compound, including pharmacokinetic/pharmacodynamics and efficacy assessment by TSPO autoradiography and CSF proteomics. Then, we showed for the first time that blockade of microglial proliferation and modification of microglial phenotype leads to an attenuation of tau-induced neurodegeneration and results in functional improvement in P301S mice. Overall, this work strongly supports the potential for inhibition of CSF1R as a target for the treatment of Alzheimer's disease and other tau-mediated neurodegenerative diseases.


Subject(s)
Imidazoles/pharmacology , Microglia/drug effects , Pyridines/pharmacology , Receptors, Granulocyte-Macrophage Colony-Stimulating Factor/metabolism , Alzheimer Disease/pathology , Animals , Cell Proliferation/drug effects , Disease Models, Animal , Genome-Wide Association Study , Humans , Imidazoles/metabolism , Mice , Mice, Transgenic , Microglia/physiology , Neurodegenerative Diseases/drug therapy , Neurogenesis , Neuroimmunomodulation/drug effects , Neuroimmunomodulation/physiology , Pyridines/metabolism , Receptors, GABA/genetics , Receptors, Granulocyte-Macrophage Colony-Stimulating Factor/antagonists & inhibitors , Tauopathies/drug therapy , tau Proteins/genetics
11.
Neurobiol Dis ; 129: 56-66, 2019 09.
Article in English | MEDLINE | ID: mdl-31085228

ABSTRACT

Non-neuronal cell types such as astrocytes can contribute to Parkinson's disease (PD) pathology. The G2019S mutation in leucine-rich repeat kinase 2 (LRRK2) is one of the most common known causes of familial PD. To characterize its effect on astrocytes, we developed a protocol to produce midbrain-patterned astrocytes from human induced pluripotent stem cells (iPSCs) derived from PD LRRK2 G2019S patients and healthy controls. RNA sequencing analysis revealed the downregulation of genes involved in the extracellular matrix in PD cases. In particular, transforming growth factor beta 1 (TGFB1), which has been shown to inhibit microglial inflammatory response in a rat model of PD, and matrix metallopeptidase 2 (MMP2), which has been shown to degrade α-synuclein aggregates, were found to be down-regulated in LRRK2 G2019S astrocytes. Our findings suggest that midbrain astrocytes carrying the LRRK2 G2019S mutation may have reduced neuroprotective capacity and may contribute to the development of PD pathology.


Subject(s)
Astrocytes/metabolism , Matrix Metalloproteinase 2/biosynthesis , Parkinson Disease/metabolism , Transforming Growth Factor beta1/biosynthesis , Aged , Down-Regulation , Female , Humans , Induced Pluripotent Stem Cells/metabolism , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/genetics , Male , Middle Aged , Mutation , Parkinson Disease/genetics , Sequence Analysis, RNA
12.
Hum Mol Genet ; 26(3): 552-566, 2017 02 01.
Article in English | MEDLINE | ID: mdl-28096185

ABSTRACT

While induced pluripotent stem cell (iPSC) technologies enable the study of inaccessible patient cell types, cellular heterogeneity can confound the comparison of gene expression profiles between iPSC-derived cell lines. Here, we purified iPSC-derived human dopaminergic neurons (DaNs) using the intracellular marker, tyrosine hydroxylase. Once purified, the transcriptomic profiles of iPSC-derived DaNs appear remarkably similar to profiles obtained from mature post-mortem DaNs. Comparison of the profiles of purified iPSC-derived DaNs derived from Parkinson's disease (PD) patients carrying LRRK2 G2019S variants to controls identified significant functional convergence amongst differentially-expressed (DE) genes. The PD LRRK2-G2019S associated profile was positively matched with expression changes induced by the Parkinsonian neurotoxin rotenone and opposed by those induced by clioquinol, a compound with demonstrated therapeutic efficacy in multiple PD models. No functional convergence amongst DE genes was observed following a similar comparison using non-purified iPSC-derived DaN-containing populations, with cellular heterogeneity appearing a greater confound than genotypic background.


Subject(s)
Induced Pluripotent Stem Cells/drug effects , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/genetics , Parkinson Disease/drug therapy , Transcriptome/genetics , Autopsy , Cells, Cultured , Clioquinol/administration & dosage , Dopamine/genetics , Dopaminergic Neurons/drug effects , Dopaminergic Neurons/metabolism , Dopaminergic Neurons/pathology , Gene Expression Profiling/methods , Gene Expression Regulation/drug effects , Humans , Induced Pluripotent Stem Cells/metabolism , Leucine-Rich Repeat Serine-Threonine Protein Kinase-2/biosynthesis , Mutation , Parkinson Disease/genetics , Parkinson Disease/pathology , Rotenone/metabolism , Rotenone/toxicity , Transcriptome/drug effects
13.
Am J Hum Genet ; 98(1): 149-64, 2016 Jan 07.
Article in English | MEDLINE | ID: mdl-26748517

ABSTRACT

Intellectual disability (ID) disorders are genetically and phenotypically extremely heterogeneous. Can this complexity be depicted in a comprehensive way as a means of facilitating the understanding of ID disorders and their underlying biology? We provide a curated database of 746 currently known genes, mutations in which cause ID (ID-associated genes [ID-AGs]), classified according to ID manifestation and associated clinical features. Using this integrated resource, we show that ID-AGs are substantially enriched with co-expression, protein-protein interactions, and specific biological functions. Systematic identification of highly enriched functional themes and phenotypes revealed typical phenotype combinations characterizing process-defined groups of ID disorders, such as chromatin-related disorders and deficiencies in DNA repair. Strikingly, phenotype classification efficiently breaks down ID-AGs into subsets with significantly elevated biological coherence and predictive power. Custom-made functional Drosophila datasets revealed further characteristic phenotypes among ID-AGs and specific clinical classes. Our study and resource provide systematic insights into the molecular and clinical landscape of ID disorders, represent a significant step toward overcoming current limitations in ID research, and prove the utility of systematic human and cross-species phenomics analyses in highly heterogeneous genetic disorders.


Subject(s)
Intellectual Disability/genetics , Mutation , Phenotype , Animals , Drosophila/genetics , Humans
14.
Genome Res ; 25(6): 802-13, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25887030

ABSTRACT

Clusters of functionally related genes can be disrupted by a single copy number variant (CNV). We demonstrate that the simultaneous disruption of multiple functionally related genes is a frequent and significant characteristic of de novo CNVs in patients with developmental disorders (P = 1 × 10(-3)). Using three different functional networks, we identified unexpectedly large numbers of functionally related genes within de novo CNVs from two large independent cohorts of individuals with developmental disorders. The presence of multiple functionally related genes was a significant predictor of a CNV's pathogenicity when compared to CNVs from apparently healthy individuals and a better predictor than the presence of known disease or haploinsufficient genes for larger CNVs. The functionally related genes found in the de novo CNVs belonged to 70% of all clusters of functionally related genes found across the genome. De novo CNVs were more likely to affect functional clusters and affect them to a greater extent than benign CNVs (P = 6 × 10(-4)). Furthermore, such clusters of functionally related genes are phenotypically informative: Different patients possessing CNVs that affect the same cluster of functionally related genes exhibit more similar phenotypes than expected (P < 0.05). The spanning of multiple functionally similar genes by single CNVs contributes substantially to how these variants exert their pathogenic effects.


Subject(s)
DNA Copy Number Variations , Developmental Disabilities/genetics , Multigene Family , Chromosomes, Human/genetics , Cluster Analysis , Databases, Genetic , Developmental Disabilities/diagnosis , Gene Regulatory Networks , Genome, Human , Healthy Volunteers , Humans , Logistic Models , Phenotype
15.
Genome Res ; 25(5): 655-66, 2015 May.
Article in English | MEDLINE | ID: mdl-25792609

ABSTRACT

Recently, a handful of intergenic long noncoding RNAs (lncRNAs) have been shown to compete with mRNAs for binding to miRNAs and to contribute to development and disease. Beyond these reports, little is yet known of the extent and functional consequences of miRNA-mediated regulation of mRNA levels by lncRNAs. To gain further insight into lncRNA-mRNA miRNA-mediated crosstalk, we reanalyzed transcriptome-wide changes induced by the targeted knockdown of over 100 lncRNA transcripts in mouse embryonic stem cells (mESCs). We predicted that, on average, almost one-fifth of the transcript level changes induced by lncRNAs are dependent on miRNAs that are highly abundant in mESCs. We validated these findings experimentally by temporally profiling transcriptome-wide changes in gene expression following the loss of miRNA biogenesis in mESCs. Following the depletion of miRNAs, we found that >50% of lncRNAs and their miRNA-dependent mRNA targets were up-regulated coordinately, consistent with their interaction being miRNA-mediated. These lncRNAs are preferentially located in the cytoplasm, and the response elements for miRNAs they share with their targets have been preserved in mammals by purifying selection. Lastly, miRNA-dependent mRNA targets of each lncRNA tended to share common biological functions. Post-transcriptional miRNA-mediated crosstalk between lncRNAs and mRNA, in mESCs, is thus surprisingly prevalent, conserved in mammals, and likely to contribute to critical developmental processes.


Subject(s)
Embryonic Stem Cells/metabolism , Gene Expression Regulation, Developmental , MicroRNAs/genetics , RNA, Long Noncoding/genetics , RNA, Messenger/genetics , Animals , Cells, Cultured , Mice , RNA Processing, Post-Transcriptional , Transcriptome
16.
PLoS Comput Biol ; 13(10): e1005816, 2017 Oct.
Article in English | MEDLINE | ID: mdl-29059180

ABSTRACT

Type 2 Diabetes (T2D) constitutes a global health burden. Efforts to uncover predisposing genetic variation have been considerable, yet detailed knowledge of the underlying pathogenesis remains poor. Here, we constructed a T2D phenotypic-linkage network (T2D-PLN), by integrating diverse gene functional information that highlight genes, which when disrupted in mice, elicit similar T2D-relevant phenotypes. Sensitising the network to T2D-relevant phenotypes enabled significant functional convergence to be detected between genes implicated in monogenic or syndromic diabetes and genes lying within genomic regions associated with T2D common risk. We extended these analyses to a recent multiethnic T2D case-control exome of 12,940 individuals that found no evidence of T2D risk association for rare frequency variants outside of previously known T2D risk loci. Examining associations involving protein-truncating variants (PTV), most at low population frequencies, the T2D-PLN was able to identify a convergent set of biological pathways that were perturbed within four of five independent T2D case/control ethnic sets of 2000 to 5000 exomes each. These same pathways were found to be over-represented among both known monogenic or syndromic diabetes genes and genes within T2D-associated common risk loci. Our study demonstrates convergent biology amongst variants representing different classes of T2D genetic risk. Although convergence was observed at the pathway level, few of the contributing genes were found in common between different cohorts or variant classes, most notably between the exome variant sets which suggests that future rare variant studies may be better focusing their power onto a single population of recent common ancestry.


Subject(s)
Diabetes Mellitus, Type 2/epidemiology , Diabetes Mellitus, Type 2/genetics , Gene Regulatory Networks/genetics , Genetic Predisposition to Disease/epidemiology , Genetic Predisposition to Disease/genetics , Polymorphism, Single Nucleotide/genetics , Proteome/genetics , Genetic Markers/genetics , Genetic Variation/genetics , Genome-Wide Association Study/methods , Humans , Prevalence , Reproducibility of Results , Risk Factors , Sensitivity and Specificity
17.
PLoS Genet ; 11(3): e1004998, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25816101

ABSTRACT

Autism spectrum disorders (ASDs) are highly heritable and characterised by deficits in social interaction and communication, as well as restricted and repetitive behaviours. Although a number of highly penetrant ASD gene variants have been identified, there is growing evidence to support a causal role for combinatorial effects arising from the contributions of multiple loci. By examining synaptic and circadian neurological phenotypes resulting from the dosage variants of unique human:fly orthologues in Drosophila, we observe numerous synergistic interactions between pairs of informatically-identified candidate genes whose orthologues are jointly affected by large de novo copy number variants (CNVs). These CNVs were found in the genomes of individuals with autism, including a patient carrying a 22q11.2 deletion. We first demonstrate that dosage alterations of the unique Drosophila orthologues of candidate genes from de novo CNVs that harbour only a single candidate gene display neurological defects similar to those previously reported in Drosophila models of ASD-associated variants. We then considered pairwise dosage changes within the set of orthologues of candidate genes that were affected by the same single human de novo CNV. For three of four CNVs with complete orthologous relationships, we observed significant synergistic effects following the simultaneous dosage change of gene pairs drawn from a single CNV. The phenotypic variation observed at the Drosophila synapse that results from these interacting genetic variants supports a concordant phenotypic outcome across all interacting gene pairs following the direction of human gene copy number change. We observe both specificity and transitivity between interactors, both within and between CNV candidate gene sets, supporting shared and distinct genetic aetiologies. We then show that different interactions affect divergent synaptic processes, demonstrating distinct molecular aetiologies. Our study illustrates mechanisms through which synergistic effects resulting from large structural variation can contribute to human disease.


Subject(s)
Autism Spectrum Disorder/genetics , DNA Copy Number Variations/genetics , DiGeorge Syndrome/genetics , Gene Dosage/genetics , Animals , Autism Spectrum Disorder/etiology , DiGeorge Syndrome/etiology , Disease Models, Animal , Drosophila melanogaster/genetics , Genetic Association Studies , Genetic Predisposition to Disease , Humans , Phenotype , Synapses/genetics
18.
PLoS Genet ; 11(3): e1005012, 2015 Mar.
Article in English | MEDLINE | ID: mdl-25781962

ABSTRACT

Readily-accessible and standardised capture of genotypic variation has revolutionised our understanding of the genetic contribution to disease. Unfortunately, the corresponding systematic capture of patient phenotypic variation needed to fully interpret the impact of genetic variation has lagged far behind. Exploiting deep and systematic phenotyping of a cohort of 197 patients presenting with heterogeneous developmental disorders and whose genomes harbour de novo CNVs, we systematically applied a range of commonly-used functional genomics approaches to identify the underlying molecular perturbations and their phenotypic impact. Grouping patients into 408 non-exclusive patient-phenotype groups, we identified a functional association amongst the genes disrupted in 209 (51%) groups. We find evidence for a significant number of molecular interactions amongst the association-contributing genes, including a single highly-interconnected network disrupted in 20% of patients with intellectual disability, and show using microcephaly how these molecular networks can be used as baits to identify additional members whose genes are variant in other patients with the same phenotype. Exploiting the systematic phenotyping of this cohort, we observe phenotypic concordance amongst patients whose variant genes contribute to the same functional association but note that (i) this relationship shows significant variation across the different approaches used to infer a commonly perturbed molecular pathway, and (ii) that the phenotypic similarities detected amongst patients who share the same inferred pathway perturbation result from these patients sharing many distinct phenotypes, rather than sharing a more specific phenotype, inferring that these pathways are best characterized by their pleiotropic effects.


Subject(s)
DNA Copy Number Variations/genetics , Developmental Disabilities/genetics , Metabolic Networks and Pathways/genetics , Protein Interaction Maps/genetics , Animals , Developmental Disabilities/metabolism , Developmental Disabilities/pathology , Gene Expression , Genetic Association Studies , Genome, Human , Genotype , Humans , Mice , Phenotype , Protein Interaction Mapping
19.
Anal Chem ; 89(4): 2440-2448, 2017 02 21.
Article in English | MEDLINE | ID: mdl-28192931

ABSTRACT

Induced pluripotent stem cells have great potential as a human model system in regenerative medicine, disease modeling, and drug screening. However, their use in medical research is hampered by laborious reprogramming procedures that yield low numbers of induced pluripotent stem cells. For further applications in research, only the best, competent clones should be used. The standard assays for pluripotency are based on genomic approaches, which take up to 1 week to perform and incur significant cost. Therefore, there is a need for a rapid and cost-effective assay able to distinguish between pluripotent and nonpluripotent cells. Here, we describe a novel multiplexed, high-throughput, and sensitive peptide-based multiple reaction monitoring mass spectrometry assay, allowing for the identification and absolute quantitation of multiple core transcription factors and pluripotency markers. This assay provides simpler and high-throughput classification into either pluripotent or nonpluripotent cells in 7 min analysis while being more cost-effective than conventional genomic tests.


Subject(s)
Induced Pluripotent Stem Cells/metabolism , Proteome/analysis , Proteomics , Cell Differentiation , Cells, Cultured , Cellular Reprogramming , Embryoid Bodies/cytology , Embryoid Bodies/metabolism , Humans , Induced Pluripotent Stem Cells/cytology , Mass Spectrometry/methods , Proteome/metabolism , Skin/cytology , Transcription Factors/analysis , Transcription Factors/metabolism
20.
Nucleic Acids Res ; 43(15): e101, 2015 Sep 03.
Article in English | MEDLINE | ID: mdl-26001969

ABSTRACT

Any given human individual carries multiple genetic variants that disrupt protein-coding genes, through structural variation, as well as nucleotide variants and indels. Predicting the phenotypic consequences of a gene disruption remains a significant challenge. Current approaches employ information from a range of biological networks to predict which human genes are haploinsufficient (meaning two copies are required for normal function) or essential (meaning at least one copy is required for viability). Using recently available study gene sets, we show that these approaches are strongly biased towards providing accurate predictions for well-studied genes. By contrast, we derive a haploinsufficiency score from a combination of unbiased large-scale high-throughput datasets, including gene co-expression and genetic variation in over 6000 human exomes. Our approach provides a haploinsufficiency prediction for over twice as many genes currently unassociated with papers listed in Pubmed as three commonly-used approaches, and outperforms these approaches for predicting haploinsufficiency for less-studied genes. We also show that fine-tuning the predictor on a set of well-studied 'gold standard' haploinsufficient genes does not improve the prediction for less-studied genes. This new score can readily be used to prioritize gene disruptions resulting from any genetic variant, including copy number variants, indels and single-nucleotide variants.


Subject(s)
Haploinsufficiency , Animals , Disease/genetics , Gene Regulatory Networks , Genomics/methods , Humans , Mice , Support Vector Machine
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