RESUMEN
Although previous studies have documented a bottleneck in the transmission of mtDNA genomes from mothers to offspring, several aspects remain unclear, including the size and nature of the bottleneck. Here, we analyze the dynamics of mtDNA heteroplasmy transmission in the Genomes of the Netherlands (GoNL) data, which consists of complete mtDNA genome sequences from 228 trios, eight dizygotic (DZ) twin quartets, and 10 monozygotic (MZ) twin quartets. Using a minor allele frequency (MAF) threshold of 2%, we identified 189 heteroplasmies in the trio mothers, of which 59% were transmitted to offspring, and 159 heteroplasmies in the trio offspring, of which 70% were inherited from the mothers. MZ twin pairs exhibited greater similarity in MAF at heteroplasmic sites than DZ twin pairs, suggesting that the heteroplasmy MAF in the oocyte is the major determinant of the heteroplasmy MAF in the offspring. We used a likelihood method to estimate the effective number of mtDNA genomes transmitted to offspring under different bottleneck models; a variable bottleneck size model provided the best fit to the data, with an estimated mean of nine individual mtDNA genomes transmitted. We also found evidence for negative selection during transmission against novel heteroplasmies (in which the minor allele has never been observed in polymorphism data). These novel heteroplasmies are enhanced for tRNA and rRNA genes, and mutations associated with mtDNA diseases frequently occur in these genes. Our results thus suggest that the female germ line is able to recognize and select against deleterious heteroplasmies.
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ADN Mitocondrial , Familia , Heterogeneidad Genética , Patrón de Herencia , Población Blanca/genética , Alelos , Femenino , Frecuencia de los Genes , Humanos , Masculino , Modelos Genéticos , Modelos Estadísticos , Mutación , Países Bajos , Polimorfismo Genético , Selección Genética , GemelosRESUMEN
Current molecular genomic approaches to human genetic disorders have led to an explosion in the identification of the genes and their encoded proteins responsible for these disorders. The identification of the gene altered by mutations in Duchenne and Becker muscular dystrophy was one of the earliest examples of this paradigm. The nearly 30 years of research partly outlined here exemplifies the road that similar current gene discovery protocols will be expected to travel, albeit much more rapidly owing to improved diagnosis of genetic disorders and an understanding of the spectrum of mutations thought to cause them. The identification of the protein dystrophin has led to a new understanding of the muscle cell membrane and the proteins involved in membrane stability, as well as new candidate genes for additional forms of muscular dystrophy. Animal models identified with naturally occurring mutations and developed by genetic manipulation have furthered the understanding of disease progression and underlying pathology. The biochemistry and molecular analysis of patient samples have led to the different dystrophin-dependent and -independent therapies that are currently close to or in human clinical trials. The lessons learned from decades of research on dystrophin have benefited the field of human genetics.
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Distrofina/metabolismo , Distrofias Musculares/fisiopatología , Distrofias Musculares/terapia , Animales , Ensayos Clínicos como Asunto , Modelos Animales de Enfermedad , Distrofina/genética , Terapia Genética/métodos , Humanos , Terapia Molecular Dirigida/métodos , Mutación , Hidrolasas Diéster Fosfóricas/metabolismo , Esteroides/uso terapéutico , Utrofina/genética , Utrofina/metabolismoRESUMEN
Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy, or CADASIL, is a hereditary cerebral small vessel disease caused by characteristic cysteine altering missense mutations in the NOTCH3 gene. NOTCH3 mutations in CADASIL result in an uneven number of cysteine residues in one of the 34 epidermal growth factor like-repeat (EGFr) domains of the NOTCH3 protein. The consequence of an unpaired cysteine residue in an EGFr domain is an increased multimerization tendency of mutant NOTCH3, leading to toxic accumulation of the protein in the (cerebro)vasculature, and ultimately reduced cerebral blood flow, recurrent stroke and vascular dementia. There is no therapy to delay or alleviate symptoms in CADASIL. We hypothesized that exclusion of the mutant EGFr domain from NOTCH3 would abolish the detrimental effect of the unpaired cysteine and thus prevent toxic NOTCH3 accumulation and the negative cascade of events leading to CADASIL. To accomplish this NOTCH3 cysteine correction by EGFr domain exclusion, we used pre-mRNA antisense-mediated skipping of specific NOTCH3 exons. Selection of these exons was achieved using in silico studies and based on the criterion that skipping of a particular exon or exon pair would modulate the protein in such a way that the mutant EGFr domain is eliminated, without otherwise corrupting NOTCH3 structure and function. Remarkably, we found that this strategy closely mimics evolutionary events, where the elimination and fusion of NOTCH EGFr domains led to the generation of four functional NOTCH homologues. We modelled a selection of exon skip strategies using cDNA constructs and show that the skip proteins retain normal protein processing, can bind ligand and be activated by ligand. We then determined the technical feasibility of targeted NOTCH3 exon skipping, by designing antisense oligonucleotides targeting exons 2-3, 4-5 and 6, which together harbour the majority of distinct CADASIL-causing mutations. Transfection of these antisense oligonucleotides into CADASIL patient-derived cerebral vascular smooth muscle cells resulted in successful exon skipping, without abrogating NOTCH3 signalling. Combined, these data provide proof of concept for this novel application of exon skipping, and are a first step towards the development of a rational therapeutic approach applicable to up to 94% of CADASIL-causing mutations.
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CADASIL/genética , Cisteína/genética , Exones/genética , Receptores Notch/genética , Secuencia de Aminoácidos , CADASIL/diagnóstico , Cisteína/química , Terapia Genética/tendencias , Células HEK293 , Humanos , Datos de Secuencia Molecular , Músculo Liso Vascular/fisiología , Técnicas de Cultivo de Órganos , Estructura Secundaria de Proteína , Receptor Notch3 , Receptores Notch/químicaRESUMEN
Many disease-associated variants affect gene expression levels (expression quantitative trait loci, eQTLs) and expression profiling using next generation sequencing (NGS) technology is a powerful way to detect these eQTLs. We analyzed 94 total blood samples from healthy volunteers with DeepSAGE to gain specific insight into how genetic variants affect the expression of genes and lengths of 3'-untranslated regions (3'-UTRs). We detected previously unknown cis-eQTL effects for GWAS hits in disease- and physiology-associated traits. Apart from cis-eQTLs that are typically easily identifiable using microarrays or RNA-sequencing, DeepSAGE also revealed many cis-eQTLs for antisense and other non-coding transcripts, often in genomic regions containing retrotransposon-derived elements. We also identified and confirmed SNPs that affect the usage of alternative polyadenylation sites, thereby potentially influencing the stability of messenger RNAs (mRNA). We then combined the power of RNA-sequencing with DeepSAGE by performing a meta-analysis of three datasets, leading to the identification of many more cis-eQTLs. Our results indicate that DeepSAGE data is useful for eQTL mapping of known and unknown transcripts, and for identifying SNPs that affect alternative polyadenylation. Because of the inherent differences between DeepSAGE and RNA-sequencing, our complementary, integrative approach leads to greater insight into the molecular consequences of many disease-associated variants.
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Regulación de la Expresión Génica/genética , Poliadenilación/genética , Sitios de Carácter Cuantitativo/genética , Retroelementos/genética , Regiones no Traducidas 3'/genética , Estudio de Asociación del Genoma Completo , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Polimorfismo de Nucleótido SimpleRESUMEN
Persistent infection of basal keratinocytes with high-risk human papillomavirus (hrHPV) may cause cancer. Keratinocytes are equipped with different pattern recognition receptors (PRRs) but hrHPV has developed ways to dampen their signals resulting in minimal inflammation and evasion of host immunity for sustained periods of time. To understand the mechanisms underlying hrHPV's capacity to evade immunity, we studied PRR signaling in non, newly, and persistently hrHPV-infected keratinocytes. We found that active infection with hrHPV hampered the relay of signals downstream of the PRRs to the nucleus, thereby affecting the production of type-I interferon and pro-inflammatory cytokines and chemokines. This suppression was shown to depend on hrHPV-induced expression of the cellular protein ubiquitin carboxyl-terminal hydrolase L1 (UCHL1) in keratinocytes. UCHL1 accomplished this by inhibiting tumor necrosis factor receptor-associated factor 3 (TRAF3) K63 poly-ubiquitination which lead to lower levels of TRAF3 bound to TANK-binding kinase 1 and a reduced phosphorylation of interferon regulatory factor 3. Furthermore, UCHL1 mediated the degradation of the NF-kappa-B essential modulator with as result the suppression of p65 phosphorylation and canonical NF-κB signaling. We conclude that hrHPV exploits the cellular protein UCHL1 to evade host innate immunity by suppressing PRR-induced keratinocyte-mediated production of interferons, cytokines and chemokines, which normally results in the attraction and activation of an adaptive immune response. This identifies UCHL1 as a negative regulator of PRR-induced immune responses and consequently its virus-increased expression as a strategy for hrHPV to persist.
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Regulación Enzimológica de la Expresión Génica/inmunología , Papillomavirus Humano 16/inmunología , Inmunidad Innata , Queratinocitos/inmunología , Infecciones por Papillomavirus/inmunología , Ubiquitina Tiolesterasa/inmunología , Regulación hacia Arriba/inmunología , Células 3T3 , Animales , Células Cultivadas , Citocinas/inmunología , Citocinas/metabolismo , Femenino , Regulación Viral de la Expresión Génica/inmunología , Papillomavirus Humano 16/metabolismo , Humanos , Queratinocitos/enzimología , Queratinocitos/patología , Queratinocitos/virología , Ratones , Infecciones por Papillomavirus/enzimología , Infecciones por Papillomavirus/patología , Fosforilación/inmunología , Proteínas Serina-Treonina Quinasas/inmunología , Proteínas Serina-Treonina Quinasas/metabolismo , Transducción de Señal/inmunología , Factor 3 Asociado a Receptor de TNF/inmunología , Factor 3 Asociado a Receptor de TNF/metabolismo , Factor de Transcripción ReIA/inmunología , Factor de Transcripción ReIA/metabolismo , Ubiquitina Tiolesterasa/biosíntesis , Ubiquitinación/inmunología , Neoplasias del Cuello Uterino/inmunología , Neoplasias del Cuello Uterino/metabolismo , Neoplasias del Cuello Uterino/patología , Neoplasias del Cuello Uterino/virologíaRESUMEN
Huntington disease is caused by expansion of a CAG repeat in the huntingtin gene that is translated into an elongated polyglutamine stretch within the N-terminal domain of the huntingtin protein. The mutation is thought to introduce a gain-of-toxic function in the mutant huntingtin protein, and blocking this toxicity by antibody binding could alleviate Huntington disease pathology. Llama single domain antibodies (VHH) directed against mutant huntingtin are interesting candidates as therapeutic agents or research tools in Huntington disease because of their small size, high thermostability, low cost of production, possibility of intracellular expression, and potency of blood-brain barrier passage. We have selected VHH from llama phage display libraries that specifically target the N-terminal domain of the huntingtin protein. Our VHH are capable of binding wild-type and mutant human huntingtin under native and denatured conditions and can be used in Huntington disease studies as a novel antibody that is easy to produce and manipulate.
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Anticuerpos Monoclonales/farmacología , Enfermedad de Huntington/terapia , Proteínas del Tejido Nervioso/análisis , Proteínas del Tejido Nervioso/inmunología , Secuencia de Aminoácidos , Especificidad de Anticuerpos , Epítopos/inmunología , Escherichia coli , Humanos , Proteína Huntingtina , Enfermedad de Huntington/inmunología , Datos de Secuencia Molecular , Unión ProteicaRESUMEN
BACKGROUND: The level of expression of the interleukin 7 receptor (IL7R) gene in blood has recently been found to be associated with familial longevity and healthy ageing. IL7R is crucial for T cell development and important for immune competence. To further investigate the IL7R pathway in ageing, we identified the closest interacting genes to construct an IL7R gene network that consisted of IL7R and six interacting genes: IL2RG, IL7, TSLP, CRLF2, JAK1 and JAK3. This network was explored for association with chronological age, familial longevity and immune-related diseases (type 2 diabetes, chronic obstructive pulmonary disease and rheumatoid arthritis) in 87 nonagenarians, 337 of their middle-aged offspring and 321 middle-aged controls from the Leiden Longevity Study (LLS). RESULTS: We observed that expression levels within the IL7R gene network were significantly different between the nonagenarians and middle-aged controls (P = 4.6 × 10(-4)), being driven by significantly lower levels of expression in the elderly of IL7, IL2RG and IL7R. After adjustment for multiple testing and white blood cell composition and in comparison with similarly aged controls, middle-aged offspring of nonagenarian siblings exhibit a lower expression level of IL7R only (P = 0.006). Higher IL7R gene expression in the combined group of middle-aged offspring and controls is associated with a higher prevalence of immune-related disease (P = 0.001). On the one hand, our results indicate that lower IL7R expression levels, as exhibited by the members of long-lived families that can be considered as 'healthy agers', are beneficial in middle age. This is augmented by the observation that higher IL7R gene expression associates with immune-related disease. On the other hand, IL7R gene expression in blood is lower in older individuals, indicating that low IL7R gene expression might associate with reduced health. Interestingly, this contradictory result is supported by the observation that a higher IL7R gene expression level is associated with better prospective survival, both in the nonagenarians (Hazard ratio (HR) = 0.63, P = 0.037) and the middle-aged individuals (HR = 0.33, P = 1.9 × 10(-4)). CONCLUSIONS: Overall, we conclude that the IL7R network reflected by gene expression levels in blood may be involved in the rate of ageing and health status of elderly individuals.
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AIMS/HYPOTHESIS: Not all obese individuals develop type 2 diabetes. Why some obese individuals retain normal glucose tolerance (NGT) is not well understood. We hypothesise that the biochemical mechanisms that underlie the function of adipose tissue can help explain the difference between obese individuals with NGT and those with type 2 diabetes. METHODS: RNA sequencing was used to analyse the transcriptome of samples extracted from visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) of obese women with NGT or type 2 diabetes who were undergoing bariatric surgery. The gene expression data was analysed by bioinformatic visualisation and statistical analyses techniques. RESULTS: A network-based approach to distinguish obese individuals with NGT from obese individuals with type 2 diabetes identified acetyl-CoA metabolic network downregulation as an important feature in the pathophysiology of type 2 diabetes in obese individuals. In general, genes within two reaction steps of acetyl-CoA were found to be downregulated in the VAT and SAT of individuals with type 2 diabetes. Upon weight loss and amelioration of metabolic abnormalities three months following bariatric surgery, the expression level of these genes recovered to levels seen in individuals with NGT. We report four novel genes associated with type 2 diabetes and recovery upon weight loss: ACAT1 (encoding acetyl-CoA acetyltransferase 1), ACACA (encoding acetyl-CoA carboxylase α), ALDH6A1 (encoding aldehyde dehydrogenase 6 family, member A1) and MTHFD1 (encoding methylenetetrahydrofolate dehydrogenase). CONCLUSIONS/INTERPRETATION: Downregulation of the acetyl-CoA network in VAT and SAT is an important feature in the pathophysiology of type 2 diabetes in obese individuals. ACAT1, ACACA, ALDH6A1 and MTHFD1 represent novel biomarkers in adipose tissue associated with type 2 diabetes in obese individuals.
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Acetilcoenzima A/metabolismo , Tejido Adiposo/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Obesidad/enzimología , Acetil-CoA C-Acetiltransferasa/genética , Acetil-CoA Carboxilasa/genética , Adipocitos/metabolismo , Adulto , Femenino , Humanos , Grasa Intraabdominal/metabolismo , Masculino , Metilenotetrahidrofolato Deshidrogenasa (NADP)/genética , Persona de Mediana Edad , Antígenos de Histocompatibilidad Menor , Obesidad/metabolismo , Análisis de Secuencia de ARN , Pérdida de Peso/fisiologíaRESUMEN
BACKGROUND: Local intramuscular administration of the antisense oligonucleotide PRO051 in patients with Duchenne's muscular dystrophy with relevant mutations was previously reported to induce the skipping of exon 51 during pre-messenger RNA splicing of the dystrophin gene and to facilitate new dystrophin expression in muscle-fiber membranes. The present phase 1-2a study aimed to assess the safety, pharmacokinetics, and molecular and clinical effects of systemically administered PRO051. METHODS: We administered weekly abdominal subcutaneous injections of PRO051 for 5 weeks in 12 patients, with each of four possible doses (0.5, 2.0, 4.0, and 6.0 mg per kilogram of body weight) given to 3 patients. Changes in RNA splicing and protein levels in the tibialis anterior muscle were assessed at two time points. All patients subsequently entered a 12-week open-label extension phase, during which they all received PRO051 at a dose of 6.0 mg per kilogram per week. Safety, pharmacokinetics, serum creatine kinase levels, and muscle strength and function were assessed. RESULTS: The most common adverse events were irritation at the administration site and, during the extension phase, mild and variable proteinuria and increased urinary α(1)-microglobulin levels; there were no serious adverse events. The mean terminal half-life of PRO051 in the circulation was 29 days. PRO051 induced detectable, specific exon-51 skipping at doses of 2.0 mg or more per kilogram. New dystrophin expression was observed between approximately 60% and 100% of muscle fibers in 10 of the 12 patients, as measured on post-treatment biopsy, which increased in a dose-dependent manner to up to 15.6% of the expression in healthy muscle. After the 12-week extension phase, there was a mean (±SD) improvement of 35.2±28.7 m (from the baseline of 384±121 m) on the 6-minute walk test. CONCLUSIONS: Systemically administered PRO051 showed dose-dependent molecular efficacy in patients with Duchenne's muscular dystrophy, with a modest improvement in the 6-minute walk test after 12 weeks of extended treatment. (Funded by Prosensa Therapeutics; Netherlands National Trial Register number, NTR1241.).
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Empalme Alternativo , Distrofia Muscular de Duchenne/tratamiento farmacológico , Oligonucleótidos/uso terapéutico , Adolescente , Niño , Preescolar , Creatina Quinasa/orina , Relación Dosis-Respuesta a Droga , Distrofina/genética , Distrofina/metabolismo , Prueba de Esfuerzo , Exones , Humanos , Inyecciones Subcutáneas , Masculino , Fuerza Muscular/efectos de los fármacos , Músculo Esquelético/química , Músculo Esquelético/metabolismo , Distrofia Muscular de Duchenne/genética , Mutación , Oligonucleótidos/administración & dosificación , Oligonucleótidos/efectos adversos , Oligonucleótidos/sangre , ARN/análisisRESUMEN
Duchenne muscular dystrophy (DMD) is a severe muscle-wasting disorder caused by the lack of functional dystrophin. There is no cure, but several clinical trials aimed to restore the synthesis of functional dystrophin are underway. The dystrophin levels needed for improvement of muscle pathology, function, and overall vitality are not known. Here, we describe the mdx/utrn(-/-)/Xist(Δhs) mouse model, which expresses a range of low dystrophin levels, depending on the degree of skewing of X inactivation in a utrophin-negative background. Mdx/utrn(-/-) mice develop severe muscle weakness, kyphosis, respiratory and heart failure, and premature death closely resembling DMD pathology. We show that at dystrophin levels < 4%, survival and motor function in these animals are greatly improved. In mice expressing >4% dystrophin, histopathology is ameliorated, as well. These findings suggest that the dystrophin levels needed to benefit vitality and functioning of patients with DMD might be lower than those needed for full protection against muscle damage.
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Distrofina/metabolismo , Distrofia Muscular Animal/patología , Distrofia Muscular Animal/fisiopatología , Distrofia Muscular de Duchenne/patología , Distrofia Muscular de Duchenne/fisiopatología , Utrofina/deficiencia , Animales , Biomarcadores/sangre , Distrofina/deficiencia , Distrofina/genética , Femenino , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos mdx , Ratones Noqueados , Fuerza Muscular/genética , Fuerza Muscular/fisiología , Músculo Esquelético/patología , Músculo Esquelético/fisiopatología , Fenotipo , Utrofina/genéticaRESUMEN
Spinocerebellar ataxia type 3 is caused by a polyglutamine expansion in the ataxin-3 protein, resulting in gain of toxic function of the mutant protein. The expanded glutamine stretch in the protein is the result of a CAG triplet repeat expansion in the penultimate exon of the ATXN3 gene. Several gene silencing approaches to reduce mutant ataxin-3 toxicity in this disease aim to lower ataxin-3 protein levels, but since this protein is involved in deubiquitination and proteasomal protein degradation, its long-term silencing might not be desirable. Here, we propose a novel protein modification approach to reduce mutant ataxin-3 toxicity by removing the toxic polyglutamine repeat from the ataxin-3 protein through antisense oligonucleotide-mediated exon skipping while maintaining important wild type functions of the protein. In vitro studies showed that exon skipping did not negatively impact the ubiquitin binding capacity of ataxin-3. Our in vivo studies showed no toxic properties of the novel truncated ataxin-3 protein. These results suggest that exon skipping may be a novel therapeutic approach to reduce polyglutamine-induced toxicity in spinocerebellar ataxia type 3.
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Enfermedad de Machado-Joseph/patología , Mutación/genética , Proteínas del Tejido Nervioso/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Represoras/metabolismo , Repeticiones de Trinucleótidos/genética , Animales , Ataxina-3 , Células Cultivadas , Análisis Mutacional de ADN , Relación Dosis-Respuesta a Droga , Exones/genética , Fibroblastos/efectos de los fármacos , Fibroblastos/metabolismo , Humanos , Enfermedad de Machado-Joseph/tratamiento farmacológico , Enfermedad de Machado-Joseph/genética , Ratones , Ratones Endogámicos C57BL , Proteínas del Tejido Nervioso/genética , Proteínas Nucleares/genética , Oligonucleótidos Antisentido/farmacología , Péptidos/metabolismo , Unión Proteica/efectos de los fármacos , Unión Proteica/genética , ARN Mensajero/metabolismo , Proteínas Represoras/genética , Transfección , Ubiquitina/metabolismoAsunto(s)
Envejecimiento/genética , ADN (Citosina-5-)-Metiltransferasas/genética , Proteínas de Unión al ADN/genética , Longevidad/genética , Mutación , Proteínas Proto-Oncogénicas/genética , Anciano , Anciano de 80 o más Años , ADN/sangre , ADN/genética , ADN Metiltransferasa 3A , Dioxigenasas , Femenino , Estudios de Seguimiento , Hematopoyesis/genética , Humanos , Masculino , Países Bajos/epidemiología , Análisis de Secuencia de ADNRESUMEN
BACKGROUND: Among the most commonly applied microarray normalization methods are intensity-dependent normalization methods such as lowess or loess algorithms. Their computational complexity makes them slow and thus less suitable for normalization of large datasets. Current implementations try to circumvent this problem by using a random subset of the data for normalization, but the impact of this modification has not been previously assessed. We developed a novel intensity-dependent normalization method for microarrays that is fast, simple and can include weighing of observations. RESULTS: Our normalization method is based on the P-spline scatterplot smoother using all data points for normalization. We show that using a random subset of the data for normalization should be avoided as unstable results can be produced. However, in certain cases normalization based on an invariant subset is desirable, for example, when groups of samples before and after intervention are compared. We show in the context of DNA methylation arrays that a constant weighted P-spline normalization yields a more reliable normalization curve than the one obtained by normalization on the invariant subset only. CONCLUSIONS: Our novel intensity-dependent normalization method is simpler and faster than current loess algorithms, and can be applied to one- and two-colour array data, similar to normalization based on loess. AVAILABILITY: An implementation of the method is currently available as an R package called TurboNorm from www.bioconductor.org.
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Ensayos Analíticos de Alto Rendimiento/normas , Análisis por Micromatrices/métodos , Análisis por Micromatrices/normas , Biología Computacional/métodos , Biología Computacional/normas , Ensayos Analíticos de Alto Rendimiento/métodos , Humanos , Distribución Aleatoria , Estándares de Referencia , Programas Informáticos , Factores de Tiempo , Estudios de Validación como AsuntoRESUMEN
Metabolomics is the comprehensive study of metabolites, which are the substrates, intermediate, and end products of cellular metabolism. The heritability of the concentrations of circulating metabolites bears relevance for evaluating their suitability as biomarkers for disease. We report aspects of familial resemblance for the concentrations in human serum of more than 100 metabolites, measured using a targeted metabolomics platform. Age- and sex-corrected monozygotic twin correlations, midparent-offspring regression coefficients, and spouse correlations in subjects from two independent cohorts (Netherlands Twin Register and Leiden Longevity Study) were estimated for each metabolite. In the Netherlands Twin Register subjects, who were largely fasting, we found significant monozygotic twin correlations for 121 out of 123 metabolites. Heritability was confirmed by midparent-offspring regression. For most detected metabolites, the correlations between spouses were considerably lower than those between twins, indicating a contribution of genetic effects to familial resemblance. Remarkably high heritability was observed for free carnitine (monozygotic twin correlation 0.66), for the amino acids serine (monozygotic twin correlation 0.77) and threonine (monozygotic twin correlation 0.64), and for phosphatidylcholine acyl-alkyl C40:3 (monozygotic twin correlation 0.77). For octenoylcarnitine, a consistent point estimate of approximately 0.50 was found for the spouse correlations in the two cohorts as well as for the monozygotic twin correlation, suggesting that familiality for this metabolite is explained by shared environment. We conclude that for the majority of metabolites targeted by the used metabolomics platform, the familial resemblance of serum concentrations is largely genetic. Our results contribute to the knowledge of the heritability of fasting serum metabolite concentrations, which is relevant for biomarker research.
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Gemelos Dicigóticos , Gemelos Monocigóticos , Enfermedades en Gemelos/genética , Ambiente , Humanos , Países Bajos , Gemelos Dicigóticos/genética , Gemelos Monocigóticos/genéticaRESUMEN
It has been postulated that aging is the consequence of an accelerated accumulation of somatic DNA mutations and that subsequent errors in the primary structure of proteins ultimately reach levels sufficient to affect organismal functions. The technical limitations of detecting somatic changes and the lack of insight about the minimum level of erroneous proteins to cause an error catastrophe hampered any firm conclusions on these theories. In this study, we sequenced the whole genome of DNA in whole blood of two pairs of monozygotic (MZ) twins, 40 and 100 years old, by two independent next-generation sequencing (NGS) platforms (Illumina and Complete Genomics). Potentially discordant single-base substitutions supported by both platforms were validated extensively by Sanger, Roche 454, and Ion Torrent sequencing. We demonstrate that the genomes of the two twin pairs are germ-line identical between co-twins, and that the genomes of the 100-year-old MZ twins are discerned by eight confirmed somatic single-base substitutions, five of which are within introns. Putative somatic variation between the 40-year-old twins was not confirmed in the validation phase. We conclude from this systematic effort that by using two independent NGS platforms, somatic single nucleotide substitutions can be detected, and that a century of life did not result in a large number of detectable somatic mutations in blood. The low number of somatic variants observed by using two NGS platforms might provide a framework for detecting disease-related somatic variants in phenotypically discordant MZ twins.
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Envejecimiento/genética , Células Sanguíneas/fisiología , Genoma Humano , Secuenciación de Nucleótidos de Alto Rendimiento , Mutación/genética , Gemelos Monocigóticos/genética , Adulto , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
While recent scans for genetic variation associated with human disease have been immensely successful in uncovering large numbers of loci, far fewer studies have focused on the underlying pathways of disease pathogenesis. Many loci which are associated with disease and complex phenotypes map to non-coding, regulatory regions of the genome, indicating that modulation of gene transcription plays a key role. Thus, this study generated genome-wide profiles of both genetic and transcriptional variation from the total blood extracts of over 500 randomly-selected, unrelated individuals. Using measurements of blood lipids, key players in the progression of atherosclerosis, three levels of biological information are integrated in order to investigate the interactions between circulating leukocytes and proximal lipid compounds. Pair-wise correlations between gene expression and lipid concentration indicate a prominent role for basophil granulocytes and mast cells, cell types central to powerful allergic and inflammatory responses. Network analysis of gene co-expression showed that the top associations function as part of a single, previously unknown gene module, the Lipid Leukocyte (LL) module. This module replicated in T cells from an independent cohort while also displaying potential tissue specificity. Further, genetic variation driving LL module expression included the single nucleotide polymorphism (SNP) most strongly associated with serum immunoglobulin E (IgE) levels, a key antibody in allergy. Structural Equation Modeling (SEM) indicated that LL module is at least partially reactive to blood lipid levels. Taken together, this study uncovers a gene network linking blood lipids and circulating cell types and offers insight into the hypothesis that the inflammatory response plays a prominent role in metabolism and the potential control of atherogenesis.
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Redes Reguladoras de Genes/genética , Inmunidad/genética , Lípidos/sangre , Adulto , Anciano , Apolipoproteínas B/sangre , Estudios de Cohortes , Regulación de la Expresión Génica , Variación Genética , Humanos , Hipersensibilidad/sangre , Hipersensibilidad/genética , Hipersensibilidad/inmunología , Mediadores de Inflamación/sangre , Leucocitos/metabolismo , Lipoproteínas HDL/sangre , Síndrome Metabólico/sangre , Síndrome Metabólico/genética , Persona de Mediana Edad , Modelos Genéticos , Obesidad/sangre , Obesidad/genética , Sitios de Carácter Cuantitativo/genética , Análisis de Regresión , Triglicéridos/sangreRESUMEN
The autosomal dominant myopathy facioscapulohumeral muscular dystrophy (FSHD1, OMIM 158900) is caused by contraction of the D4Z4 repeat array on 4qter. We show that this contraction causes marked hypomethylation of the contracted D4Z4 allele in individuals with FSHD1. Individuals with phenotypic FSHD1, who are clinically identical to FSHD1 but have an unaltered D4Z4, also have hypomethylation of D4Z4. These results strongly suggest that hypomethylation of D4Z4 is a key event in the cascade of epigenetic events causing FSHD1.
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Cromosomas Humanos Par 4/genética , Metilación de ADN , Distrofia Muscular Facioescapulohumeral/genética , Polimorfismo Genético , Secuencias Repetitivas de Ácidos Nucleicos/genética , Femenino , Genotipo , Humanos , Masculino , LinajeRESUMEN
Contractions in the polymorphic D4Z4 repeat array of subtelomere 4qter cause autosomal dominant facioscapulohumeral muscular dystrophy in humans. A polymorphic segment of 10 kb directly distal to D4Z4 exists in two allelic forms, 4qA and 4qB. Although both alleles are equally common in the general population, we now report that FSHD is associated solely with the 4qA allele.
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Cromosomas Humanos Par 4 , Distrofia Muscular Facioescapulohumeral/genética , Polimorfismo Genético , Femenino , Humanos , Masculino , Linaje , Secuencias Repetitivas de Ácidos Nucleicos , TelómeroRESUMEN
Only a small proportion of cancers result from familial cancer syndromes with Mendelian inheritance. Nonfamilial, 'sporadic' cancers, which represent most cancer cases, also have a significant hereditary component, but the genes involved have low penetrance and are extremely difficult to detect. Therefore, mapping and cloning of quantitative trait loci (QTLs) for cancer susceptibility in animals could help identify homologous genes in humans. Several cancer-susceptibility QTLs have been mapped in mice and rats, but none have been cloned so far. Here we report the positional cloning of the mouse gene Scc1 (Susceptibility to colon cancer 1) and the identification of Ptprj, encoding a receptor-type protein tyrosine phosphatase, as the underlying gene. In human colon, lung and breast cancers, we show frequent deletion of PTPRJ, allelic imbalance in loss of heterozygosity (LOH) and missense mutations. Our data suggest that PTPRJ is relevant to the development of several different human cancers.
Asunto(s)
Adenocarcinoma/genética , Proteínas de Ciclo Celular/genética , Neoplasias del Colon/genética , Proteínas Tirosina Fosfatasas/genética , Adenocarcinoma/patología , Animales , Neoplasias de la Mama/genética , Proteínas de Ciclo Celular/química , Proteínas Cromosómicas no Histona , Mapeo Cromosómico , Neoplasias del Colon/inducido químicamente , Dimetilhidrazinas , Eliminación de Gen , Silenciador del Gen , Marcadores Genéticos , Humanos , Pérdida de Heterocigocidad , Neoplasias Pulmonares/genética , Ratones , Ratones Endogámicos BALB C , Ratones Endogámicos , Proteínas Nucleares , Fosfoproteínas , Polimorfismo Genético , Carácter Cuantitativo Heredable , Proteínas Tirosina Fosfatasas Clase 3 Similares a Receptores , Proteínas de Saccharomyces cerevisiae , Homología de Secuencia de Aminoácido , Homología de Secuencia de Ácido NucleicoRESUMEN
Gene regulatory networks give important insights into the mechanisms underlying physiology and pathophysiology. The derivation of gene regulatory networks from high-throughput expression data via machine learning strategies is problematic as the reliability of these models is often compromised by limited and highly variable samples, heterogeneity in transcript isoforms, noise, and other artifacts. Here, we develop a novel algorithm, dubbed Dandelion, in which we construct and train intraspecies Bayesian networks that are translated and assessed on independent test sets from other species in a reiterative procedure. The interspecies disease networks are subjected to multi-layers of analysis and evaluation, leading to the identification of the most consistent relationships within the network structure. In this study, we demonstrate the performance of our algorithms on datasets from animal models of oculopharyngeal muscular dystrophy (OPMD) and patient materials. We show that the interspecies network of genes coding for the proteasome provide highly accurate predictions on gene expression levels and disease phenotype. Moreover, the cross-species translation increases the stability and robustness of these networks. Unlike existing modeling approaches, our algorithms do not require assumptions on notoriously difficult one-to-one mapping of protein orthologues or alternative transcripts and can deal with missing data. We show that the identified key components of the OPMD disease network can be confirmed in an unseen and independent disease model. This study presents a state-of-the-art strategy in constructing interspecies disease networks that provide crucial information on regulatory relationships among genes, leading to better understanding of the disease molecular mechanisms.