RESUMO
Ewing sarcoma (EwS) is a rare bone and soft tissue malignancy driven by chromosomal translocations encoding chimeric transcription factors, such as EWSR1-FLI1, that bind GGAA motifs forming novel enhancers that alter nearby expression. We propose that germline microsatellite variation at the 6p25.1 EwS susceptibility locus could impact downstream gene expression and EwS biology. We performed targeted long-read sequencing of EwS blood DNA to characterize variation and genomic features important for EWSR1-FLI1 binding. We identified 50 microsatellite alleles at 6p25.1 and observed that EwS-affected individuals had longer alleles (>135 bp) with more GGAA repeats. The 6p25.1 GGAA microsatellite showed chromatin features of an EWSR1-FLI1 enhancer and regulated expression of RREB1, a transcription factor associated with RAS/MAPK signaling. RREB1 knockdown reduced proliferation and clonogenic potential and reduced expression of cell cycle and DNA replication genes. Our integrative analysis at 6p25.1 details increased binding of longer GGAA microsatellite alleles with acquired EWSR-FLI1 to promote Ewing sarcomagenesis by RREB1-mediated proliferation.
Assuntos
Neoplasias Ósseas , Sarcoma de Ewing , Humanos , Alelos , Neoplasias Ósseas/genética , Neoplasias Ósseas/patologia , Linhagem Celular Tumoral , Regulação Neoplásica da Expressão Gênica , Proteínas de Fusão Oncogênica/genética , Proteínas de Fusão Oncogênica/metabolismo , Proteína Proto-Oncogênica c-fli-1/genética , Proteína Proto-Oncogênica c-fli-1/metabolismo , Proteína EWS de Ligação a RNA/genética , Proteína EWS de Ligação a RNA/metabolismo , Sarcoma de Ewing/genética , Sarcoma de Ewing/metabolismo , Sarcoma de Ewing/patologiaRESUMO
Approximately 1.5 billion people worldwide are overweight or affected by obesity, and are at risk of developing type 2 diabetes, cardiovascular disease and related metabolic and inflammatory disturbances. Although the mechanisms linking adiposity to associated clinical conditions are poorly understood, recent studies suggest that adiposity may influence DNA methylation, a key regulator of gene expression and molecular phenotype. Here we use epigenome-wide association to show that body mass index (BMI; a key measure of adiposity) is associated with widespread changes in DNA methylation (187 genetic loci with P < 1 × 10-7, range P = 9.2 × 10-8 to 6.0 × 10-46; n = 10,261 samples). Genetic association analyses demonstrate that the alterations in DNA methylation are predominantly the consequence of adiposity, rather than the cause. We find that methylation loci are enriched for functional genomic features in multiple tissues (P < 0.05), and show that sentinel methylation markers identify gene expression signatures at 38 loci (P < 9.0 × 10-6, range P = 5.5 × 10-6 to 6.1 × 10-35, n = 1,785 samples). The methylation loci identify genes involved in lipid and lipoprotein metabolism, substrate transport and inflammatory pathways. Finally, we show that the disturbances in DNA methylation predict future development of type 2 diabetes (relative risk per 1 standard deviation increase in methylation risk score: 2.3 (2.07-2.56); P = 1.1 × 10-54). Our results provide new insights into the biologic pathways influenced by adiposity, and may enable development of new strategies for prediction and prevention of type 2 diabetes and other adverse clinical consequences of obesity.
Assuntos
Adiposidade/genética , Índice de Massa Corporal , Metilação de DNA/genética , Diabetes Mellitus Tipo 2/genética , Epigênese Genética , Epigenômica , Estudo de Associação Genômica Ampla , Obesidade/genética , Tecido Adiposo/metabolismo , Povo Asiático/genética , Sangue/metabolismo , Estudos de Coortes , Diabetes Mellitus Tipo 2/complicações , Europa (Continente)/etnologia , Feminino , Marcadores Genéticos , Predisposição Genética para Doença , Humanos , Índia/etnologia , Masculino , Obesidade/sangue , Obesidade/complicações , Sobrepeso/sangue , Sobrepeso/complicações , Sobrepeso/genética , População Branca/genéticaRESUMO
AIMS/HYPOTHESIS: Type 2 diabetes is a complex metabolic disease with increasing prevalence worldwide. Improving the prediction of incident type 2 diabetes using epigenetic markers could help tailor prevention efforts to those at the highest risk. The aim of this study was to identify predictive methylation markers for incident type 2 diabetes by combining epigenome-wide association study (EWAS) results from five prospective European cohorts. METHODS: We conducted a meta-analysis of EWASs in blood collected 7-10 years prior to type 2 diabetes diagnosis. DNA methylation was measured with Illumina Infinium Methylation arrays. A total of 1250 cases and 1950 controls from five longitudinal cohorts were included: Doetinchem, ESTHER, KORA1, KORA2 and EPIC-Norfolk. Associations between DNA methylation and incident type 2 diabetes were examined using robust linear regression with adjustment for potential confounders. Inverse-variance fixed-effects meta-analysis of cohort-level individual CpG EWAS estimates was performed using METAL. The methylGSA R package was used for gene set enrichment analysis. Confirmation of genome-wide significant CpG sites was performed in a cohort of Indian Asians (LOLIPOP, UK). RESULTS: The meta-analysis identified 76 CpG sites that were differentially methylated in individuals with incident type 2 diabetes compared with control individuals (p values <1.1 × 10-7). Sixty-four out of 76 (84.2%) CpG sites were confirmed by directionally consistent effects and p values <0.05 in an independent cohort of Indian Asians. However, on adjustment for baseline BMI only four CpG sites remained genome-wide significant, and addition of the 76 CpG methylation risk score to a prediction model including established predictors of type 2 diabetes (age, sex, BMI and HbA1c) showed no improvement (AUC 0.757 vs 0.753). Gene set enrichment analysis of the full epigenome-wide results clearly showed enrichment of processes linked to insulin signalling, lipid homeostasis and inflammation. CONCLUSIONS/INTERPRETATION: By combining results from five European cohorts, and thus significantly increasing study sample size, we identified 76 CpG sites associated with incident type 2 diabetes. Replication of 64 CpGs in an independent cohort of Indian Asians suggests that the association between DNA methylation levels and incident type 2 diabetes is robust and independent of ethnicity. Our data also indicate that BMI partly explains the association between DNA methylation and incident type 2 diabetes. Further studies are required to elucidate the underlying biological mechanisms and to determine potential causal roles of the differentially methylated CpG sites in type 2 diabetes development.
Assuntos
Diabetes Mellitus Tipo 2 , Epigenoma , Ilhas de CpG/genética , Metilação de DNA/genética , Diabetes Mellitus Tipo 2/epidemiologia , Diabetes Mellitus Tipo 2/genética , Epigênese Genética/genética , Estudo de Associação Genômica Ampla , Humanos , Estudos ProspectivosRESUMO
Circulating levels of adiponectin, an adipocyte-secreted protein associated with cardiovascular and metabolic risk, are highly heritable. To gain insights into the biology that regulates adiponectin levels, we performed an exome array meta-analysis of 265,780 genetic variants in 67,739 individuals of European, Hispanic, African American, and East Asian ancestry. We identified 20 loci associated with adiponectin, including 11 that had been reported previously (p < 2 × 10-7). Comparison of exome array variants to regional linkage disequilibrium (LD) patterns and prior genome-wide association study (GWAS) results detected candidate variants (r2 > .60) spanning as much as 900 kb. To identify potential genes and mechanisms through which the previously unreported association signals act to affect adiponectin levels, we assessed cross-trait associations, expression quantitative trait loci in subcutaneous adipose, and biological pathways of nearby genes. Eight of the nine loci were also associated (p < 1 × 10-4) with at least one obesity or lipid trait. Candidate genes include PRKAR2A, PTH1R, and HDAC9, which have been suggested to play roles in adipocyte differentiation or bone marrow adipose tissue. Taken together, these findings provide further insights into the processes that influence circulating adiponectin levels.
Assuntos
Adiponectina/genética , Tecido Adiposo/patologia , Exoma/genética , Predisposição Genética para Doença , Lipídeos/análise , Obesidade/etiologia , Polimorfismo de Nucleotídeo Único , Tecido Adiposo/metabolismo , Adolescente , Adulto , Negro ou Afro-Americano/genética , Idoso , Idoso de 80 Anos ou mais , Feminino , Hispânico ou Latino/genética , Humanos , Masculino , Pessoa de Meia-Idade , Obesidade/patologia , Fenótipo , Locos de Características Quantitativas , População Branca/genética , Adulto JovemRESUMO
Progranulin is a secreted protein with important functions in processes including immune and inflammatory response, metabolism and embryonic development. The present study aimed at identification of genetic factors determining progranulin concentrations. We conducted a genome-wide association meta-analysis for serum progranulin in three independent cohorts from Europe: Sorbs (N = 848) and KORA (N = 1628) from Germany and PPP-Botnia (N = 335) from Finland (total N = 2811). Single nucleotide polymorphisms (SNPs) associated with progranulin levels were replicated in two additional German cohorts: LIFE-Heart Study (Leipzig; N = 967) and Metabolic Syndrome Berlin Potsdam (Berlin cohort; N = 833). We measured mRNA expression of genes in peripheral blood mononuclear cells (PBMC) by micro-arrays and performed mRNA expression quantitative trait and expression-progranulin association studies to functionally substantiate identified loci. Finally, we conducted siRNA silencing experiments in vitro to validate potential candidate genes within the associated loci. Heritability of circulating progranulin levels was estimated at 31.8% and 26.1% in the Sorbs and LIFE-Heart cohort, respectively. SNPs at three loci reached study-wide significance (rs660240 in CELSR2-PSRC1-MYBPHL-SORT1, rs4747197 in CDH23-PSAP and rs5848 in GRN) explaining 19.4%/15.0% of the variance and 61%/57% of total heritability in the Sorbs/LIFE-Heart Study. The strongest evidence for association was at rs660240 (P = 5.75 × 10-50), which was also associated with mRNA expression of PSRC1 in PBMC (P = 1.51 × 10-21). Psrc1 knockdown in murine preadipocytes led to a consecutive 30% reduction in progranulin secretion. In conclusion, the present meta-GWAS combined with mRNA expression identified three loci associated with progranulin and supports the role of PSRC1 in the regulation of progranulin secretion.
Assuntos
Estudo de Associação Genômica Ampla/métodos , Progranulinas/sangue , Animais , Genótipo , Humanos , Leucócitos Mononucleares/metabolismo , Camundongos , Fosfoproteínas/genética , Fosfoproteínas/metabolismo , Polimorfismo de Nucleotídeo Único/genética , RNA Mensageiro/metabolismoRESUMO
Large artery atherosclerotic stroke (LAS) shows substantial heritability not explained by previous genome-wide association studies. Here, we explore the role of coding variation in LAS by analyzing variants on the HumanExome BeadChip in a total of 3,127 cases and 9,778 controls from Europe, Australia, and South Asia. We report on a nonsynonymous single-nucleotide variant in serpin family A member 1 (SERPINA1) encoding alpha-1 antitrypsin [AAT; p.V213A; P = 5.99E-9, odds ratio (OR) = 1.22] and confirm histone deacetylase 9 (HDAC9) as a major risk gene for LAS with an association in the 3'-UTR (rs2023938; P = 7.76E-7, OR = 1.28). Using quantitative microscale thermophoresis, we show that M1 (A213) exhibits an almost twofold lower dissociation constant with its primary target human neutrophil elastase (NE) in lipoprotein-containing plasma, but not in lipid-free plasma. Hydrogen/deuterium exchange combined with mass spectrometry further revealed a significant difference in the global flexibility of the two variants. The observed stronger interaction with lipoproteins in plasma and reduced global flexibility of the Val-213 variant most likely improve its local availability and reduce the extent of proteolytic inactivation by other proteases in atherosclerotic plaques. Our results indicate that the interplay between AAT, NE, and lipoprotein particles is modulated by the gate region around position 213 in AAT, far away from the unaltered reactive center loop (357-360). Collectively, our findings point to a functionally relevant balance between lipoproteins, proteases, and AAT in atherosclerosis.
Assuntos
Histona Desacetilases/genética , Placa Aterosclerótica/complicações , Polimorfismo de Nucleotídeo Único , Proteínas Repressoras/genética , Acidente Vascular Cerebral/genética , alfa 1-Antitripsina/genética , Regiões 3' não Traduzidas , Medição da Troca de Deutério , Estudos de Associação Genética , Humanos , Elastase de Leucócito/metabolismo , Espectrometria de Massas , Placa Aterosclerótica/genética , Acidente Vascular Cerebral/etiologia , alfa 1-Antitripsina/metabolismoRESUMO
BACKGROUND: The discovery of low-frequency coding variants affecting the risk of coronary artery disease has facilitated the identification of therapeutic targets. METHODS: Through DNA genotyping, we tested 54,003 coding-sequence variants covering 13,715 human genes in up to 72,868 patients with coronary artery disease and 120,770 controls who did not have coronary artery disease. Through DNA sequencing, we studied the effects of loss-of-function mutations in selected genes. RESULTS: We confirmed previously observed significant associations between coronary artery disease and low-frequency missense variants in the genes LPA and PCSK9. We also found significant associations between coronary artery disease and low-frequency missense variants in the genes SVEP1 (p.D2702G; minor-allele frequency, 3.60%; odds ratio for disease, 1.14; P=4.2×10(-10)) and ANGPTL4 (p.E40K; minor-allele frequency, 2.01%; odds ratio, 0.86; P=4.0×10(-8)), which encodes angiopoietin-like 4. Through sequencing of ANGPTL4, we identified 9 carriers of loss-of-function mutations among 6924 patients with myocardial infarction, as compared with 19 carriers among 6834 controls (odds ratio, 0.47; P=0.04); carriers of ANGPTL4 loss-of-function alleles had triglyceride levels that were 35% lower than the levels among persons who did not carry a loss-of-function allele (P=0.003). ANGPTL4 inhibits lipoprotein lipase; we therefore searched for mutations in LPL and identified a loss-of-function variant that was associated with an increased risk of coronary artery disease (p.D36N; minor-allele frequency, 1.9%; odds ratio, 1.13; P=2.0×10(-4)) and a gain-of-function variant that was associated with protection from coronary artery disease (p.S447*; minor-allele frequency, 9.9%; odds ratio, 0.94; P=2.5×10(-7)). CONCLUSIONS: We found that carriers of loss-of-function mutations in ANGPTL4 had triglyceride levels that were lower than those among noncarriers; these mutations were also associated with protection from coronary artery disease. (Funded by the National Institutes of Health and others.).
Assuntos
Angiopoietinas/genética , Moléculas de Adesão Celular/genética , Doença da Artéria Coronariana/genética , Lipase Lipoproteica/genética , Mutação , Triglicerídeos/sangue , Idoso , Proteína 4 Semelhante a Angiopoietina , Feminino , Técnicas de Genotipagem , Humanos , Lipase Lipoproteica/antagonistas & inibidores , Lipase Lipoproteica/metabolismo , Masculino , Pessoa de Meia-Idade , Mutação de Sentido Incorreto , Fatores de Risco , Análise de Sequência de DNA , Triglicerídeos/genéticaRESUMO
Animal sterols, plant sterols and bile acids in stool samples have been suggested as biomarkers of dietary intake. It is still unknown whether they also reflect long-term habitual dietary intake and can be used in aetiological research. In a subgroup of the Cooperative Health Research in the Augsburg Region (KORA FF4) study, habitual dietary intake was estimated based on repeated 24-h food list and a FFQ. Stool samples were collected according to a standard operating procedure and those meeting the quality criteria were extracted and analysed by means of a metabolomics technique. The present study is based on data from 513 men and 495 women with a mean age of 60 and 58 years, respectively, for which faecal animal and plant sterols and bile acids concentrations and dietary intake data were available. In adjusted regression models, the associations between food intake and log-normalised metabolite concentrations were analysed. Bonferroni correction was used to account for multiple testing. In this population-based sample, associations between habitual dietary intake and faecal concentrations of animal sterols were identified, while the impact of usual diet on bile acids was limited. A habitual diet high in 'fruits' and 'nuts and seeds' is associated with lower animal faecal sterols concentrations, whereas a diet high in 'meat and meat products' is positively related to faecal concentrations of animal sterols. A positive association between glycocholate and fruit consumption was found. Further studies are necessary for evaluation of faecal animal sterols as biomarkers of diet. The findings need to be confirmed in other populations with diverse dietary habits.
Assuntos
Ácidos e Sais Biliares/análise , Dieta , Ingestão de Alimentos , Fezes/química , Esteróis/análise , Adulto , Idoso , Antropometria , Biomarcadores/análise , Colesterol/metabolismo , Fibras na Dieta/análise , Feminino , Frutas , Alemanha/epidemiologia , Ácido Glicocólico/metabolismo , Humanos , Estilo de Vida , Masculino , Carne/análise , Metabolômica , Pessoa de Meia-Idade , Nozes , Fitosteróis , Sementes , Inquéritos e QuestionáriosRESUMO
Epigenetic DNA modifications in genes related to the hypothalamic-pituitary-adrenal (HPA) axis are discussed as a mechanism underlying the association between prenatal depression and altered child HPA activity. In a longitudinal study, DNA methylation changes related to prenatal depressive symptoms were investigated in 167 children aged 6 to 9 years. At six candidate genes, 126 cytosine-guanine dinucleotides were considered without correcting for multiple testing due to the exploratory nature of the study. Further associations with the basal child HPA activity were examined. Children exposed to prenatal depressive symptoms exhibited lower bedtime cortisol (p = .003, ηp2 = 0.07) and a steeper diurnal slope (p = .023, ηp2 = 0.06). For total cortisol release, prenatal exposure was related to lower cortisol release in boys, and higher release in girls. Furthermore, prenatal depressive symptoms were associated with altered methylation in the glucocorticoid receptor gene (NR3C1), the mineralocorticoid receptor gene (NR3C2), and the serotonin receptor gene (SLC6A4), with some sex-specific effects (p = .012-.040, ηp2 = 0.03-0.04). In boys, prenatal depressive symptoms predicted bedtime cortisol mediated by NR3C2 methylation, indirect effect = -0.07, 95% confidence interval [-0.16, -0.02]. Results indicate relations of prenatal depressive symptoms to both child basal HPA activity and DNA methylation, partially fitting a mediation model, with exposed boys and girls being affected differently.
Assuntos
Metilação de DNA , Depressão/metabolismo , Hidrocortisona/análise , Sistema Hipotálamo-Hipofisário/metabolismo , Sistema Hipófise-Suprarrenal/metabolismo , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Adulto , Criança , Depressão/genética , Epigênese Genética , Feminino , Humanos , Estudos Longitudinais , Masculino , Gravidez , Efeitos Tardios da Exposição Pré-Natal/genética , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismo , Receptores de Mineralocorticoides/genética , Receptores de Mineralocorticoides/metabolismo , Proteínas da Membrana Plasmática de Transporte de Serotonina/genética , Proteínas da Membrana Plasmática de Transporte de Serotonina/metabolismoRESUMO
More than a million childhood diarrhoeal episodes occur worldwide each year, and in developed countries a considerable part of them are caused by viral infections. In this study, we aimed to search for genetic variants associated with diarrhoeal disease in young children by meta-analyzing genome-wide association studies, and to elucidate plausible biological mechanisms. The study was conducted in the context of the Early Genetics and Lifecourse Epidemiology (EAGLE) consortium. Data about diarrhoeal disease in two time windows (around 1 year of age and around 2 years of age) was obtained via parental questionnaires, doctor interviews or medical records. Standard quality control and statistical tests were applied to the 1000 Genomes imputed genotypic data. The meta-analysis (N = 5758) followed by replication (N = 3784) identified a genome-wide significant association between rs8111874 and diarrhoea at age 1 year. Conditional analysis suggested that the causal variant could be rs601338 (W154X) in the FUT2 gene. Children with the A allele, which results in a truncated FUT2 protein, had lower risk of diarrhoea. FUT2 participates in the production of histo-blood group antigens and has previously been implicated in the susceptibility to infections, including Rotavirus and Norovirus Gene-set enrichment analysis suggested pathways related to the histo-blood group antigen production, and the regulation of ion transport and blood pressure. Among others, the gastrointestinal tract, and the immune and neuro-secretory systems were detected as relevant organs. In summary, this genome-wide association meta-analysis suggests the implication of the FUT2 gene in diarrhoeal disease in young children from the general population.
Assuntos
Diarreia/genética , Fucosiltransferases/genética , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Alelos , Pré-Escolar , Diarreia/patologia , Feminino , Genótipo , Humanos , Lactente , Masculino , Polimorfismo de Nucleotídeo Único , Galactosídeo 2-alfa-L-FucosiltransferaseRESUMO
PURPOSE OF REVIEW: Glucose metabolism is a central process in mammalian energy homeostasis. Its deregulation is a key factor in development of metabolic disease like diabetes and cancer. In recent decades, our understanding of gene regulation at the signaling, chromatin and posttranscriptional levels has seen dramatic developments. RECENT FINDINGS: A number of epigenetic mechanisms that do not affect the genetic code can be assessed with new technologies. However, increasing complexity becomes a major challenge for translation into clinical application. SUMMARY: The current review provides an update of transcriptional control of glucose metabolism, focusing on epigenetic regulators, DNA-methylation, histone modifications and noncoding RNAs. Recent studies heavily support the importance of those mechanisms for future therapeutics and preventive efforts for metabolic diseases.
Assuntos
Epigênese Genética/fisiologia , Glucose/metabolismo , Homeostase/fisiologia , Acetilação , Animais , Metilação de DNA/fisiologia , Código das Histonas/fisiologia , Histonas/metabolismo , Humanos , Doenças Metabólicas/prevenção & controle , Doenças Metabólicas/terapia , Metilação , RNA não TraduzidoRESUMO
Angiopoietin-like protein 8 (ANGPTL8)/betatrophin expression in visceral adipose tissue and associations with circulating fatty acid profile have not yet been investigated.Forty subjects were included in a cross-sectional study, 57 in a dietary weight reduction intervention. Circulating Angiopoietin-like protein 8/betatrophin was measured in all subjects. Liver and adipose tissue were sampled and plasma fatty acids and tissue Angiopoietin-like protein 8/betatrophin expression were evaluated in the cross-sectional study. In the intervention study oral glucose testing and liver magnetic resonance scanning at baseline and after 6 months were performed. Angiopoietin-like protein 8/betatrophin mRNA was increased in visceral compared to subcutaneous adipose tissue (p<0.001). Circulating ANGPTL8/betatrophin correlated with liver steatosis (r=0.42, p=0.047), triacylglycerols (r=0.34, p=0.046), saturated (r=0.43, p=0.022), monounsaturated (r=0.51, p=0.007), and polyunsaturated fatty acids (r=-0.53, p=0.004). In the intervention study, baseline Angiopoietin-like protein 8/betatrophin correlated with age (r=0.32, p=0.010) and triacylglycerols (r=0.30, p=0.02) and was increased with hepatic steatosis (p=0.033). Weight loss reduced liver fat by 45% and circulating Angiopoietin-like protein 8/betatrophin by 11% (288±17 vs. 258±17 pg/ml; p=0.015). Angiopoietin-like protein 8/betatrophin is related to liver steatosis, while visceral adipose tissue represents an additional site of expression in humans.
Assuntos
Proteínas Semelhantes a Angiopoietina/genética , Fígado Gorduroso/genética , Gordura Intra-Abdominal/metabolismo , Hormônios Peptídicos/genética , Proteína 8 Semelhante a Angiopoietina , Proteínas Semelhantes a Angiopoietina/metabolismo , Estudos de Coortes , Dieta , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Hepatopatia Gordurosa não Alcoólica/genética , Hormônios Peptídicos/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismoRESUMO
AIMS: Molecular adaptations in human non-alcoholic fatty liver disease (NAFLD) are incompletely understood. This study investigated the main gene categories related to hepatic de novo lipogenesis and lipid oxidation capacity. METHODS: Liver specimens of 48 subjects were histologically classified according to steatosis severity. In-depth analyses were undertaken using real-time polymerase chain reaction, immunoblotting, and immunohistochemistry. Lipid profiles were analyzed by gas chromatography/flame ionization detection, and effects of key fatty acids were studied in primary human hepatocytes. RESULTS: Real-time polymerase chain reaction, immunoblotting, and immunohistochemistry indicated 5'AMP-activated protein kinase (AMPK) to be increased with steatosis score ≥ 2 (all P < 0.05), including various markers of de novo lipogenesis and lipid degradation (all P < 0.05). Regarding endoplasmic reticulum stress, X-Box binding protein-1 (XBP1) was upregulated in steatosis score ≥ 2 (P = 0.029) and correlated with plasma palmitate (r = 0.34; P = 0.035). Palmitate incubation of primary human hepatocytes increased XBP1 and downstream stearoyl CoA desaturase-1 mRNA expression (both P < 0.05). Moreover, plasma and liver tissue exposed a NAFLD-related lipid profile with reduced polyunsaturated/saturated fatty acid ratio, increased palmitate and palmitoleate, and elevated lipogenesis and desaturation indices with steatosis score ≥ 2 (all P < 0.05). CONCLUSION: In humans with advanced fatty liver disease, hepatic AMPK protein is upregulated, potentially in a compensatory manner. Moreover, pathways of lipid synthesis and degradation are co-activated in subjects with advanced steatosis. Palmitate may drive lipogenesis by activating XBP1-mediated endoplasmic reticulum stress and represent a target for future dietary or pharmacological intervention.
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Chemerin is an adipokine proposed to link obesity and chronic inflammation of adipose tissue. Genetic factors determining chemerin release from adipose tissue are yet unknown. We conducted a meta-analysis of genome-wide association studies (GWAS) for serum chemerin in three independent cohorts from Europe: Sorbs and KORA from Germany and PPP-Botnia from Finland (total Nâ=â2,791). In addition, we measured mRNA expression of genes within the associated loci in peripheral mononuclear cells by micro-arrays, and within adipose tissue by quantitative RT-PCR and performed mRNA expression quantitative trait and expression-chemerin association studies to functionally substantiate our loci. Heritability estimate of circulating chemerin levels was 16.2% in the Sorbs cohort. Thirty single nucleotide polymorphisms (SNPs) at chromosome 7 within the retinoic acid receptor responder 2 (RARRES2)/Leucine Rich Repeat Containing (LRRC61) locus reached genome-wide significance (p<5.0×10-8) in the meta-analysis (the strongest evidence for association at rs7806429 with pâ=â7.8×10-14, betaâ=â-0.067, explained variance 2.0%). All other SNPs within the cluster were in linkage disequilibrium with rs7806429 (minimum r2â=â0.43 in the Sorbs cohort). The results of the subgroup analyses of males and females were consistent with the results found in the total cohort. No significant SNP-sex interaction was observed. rs7806429 was associated with mRNA expression of RARRES2 in visceral adipose tissue in women (p<0.05 after adjusting for age and body mass index). In conclusion, the present meta-GWAS combined with mRNA expression studies highlights the role of genetic variation in the RARRES2 locus in the regulation of circulating chemerin concentrations.
Assuntos
Quimiocinas/sangue , Quimiocinas/genética , Peptídeos e Proteínas de Sinalização Intercelular/sangue , Peptídeos e Proteínas de Sinalização Intercelular/genética , Quimiocinas/metabolismo , Expressão Gênica , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos , Peptídeos e Proteínas de Sinalização Intercelular/metabolismo , Gordura Intra-Abdominal/metabolismo , Obesidade/sangue , Obesidade/genética , Polimorfismo de Nucleotídeo Único , Gordura Subcutânea/metabolismoRESUMO
In humans and rodents, risk of metabolic syndrome is sexually dimorphic, with an increased incidence in males. Additionally, the protective role of female gonadal hormones is ostensible, as prevalence of type 2 diabetes mellitus (T2DM) increases after menopause. Here, we investigated the influence of estrogen (E2) on the onset of T2DM in female New Zealand obese (NZO) mice. Diabetes prevalence (defined as blood glucose levels >16.6 mmol/l) of NZO females on high-fat diet (60 kcal% fat) in week 22 was 43%. This was markedly dependent on liver fat content in week 10, as detected by computed tomography. Only mice with a liver fat content >9% in week 10 plus glucose levels >10 mmol/l in week 9 developed hyperglycemia by week 22. In addition, at 11 wk, diacylglycerols were elevated in livers of diabetes-prone mice compared with controls. Hepatic expression profiles obtained from diabetes-prone and -resistant mice at 11 wk revealed increased abundance of two transcripts in diabetes-prone mice: Mogat1, which catalyzes the synthesis of diacylglycerols from monoacylglycerol and fatty acyl-CoA, and the fatty acid transporter Cd36. E2 treatment of diabetes-prone mice for 10 wk prevented any further increase in liver fat content and reduced diacylglycerols and the abundance of Mogat1 and Cd36, leading to a reduction of diabetes prevalence and an improved glucose tolerance compared with untreated mice. Our data indicate that early elevation of hepatic Cd36 and Mogat1 associates with increased production and accumulation of triglycerides and diacylglycerols, presumably resulting in reduced hepatic insulin sensitivity and leading to later onset of T2DM.
Assuntos
Diabetes Mellitus Tipo 2/metabolismo , Estrogênios/farmacologia , Ácidos Graxos/metabolismo , Gordura Intra-Abdominal/metabolismo , Fígado/metabolismo , Obesidade/metabolismo , Animais , Feminino , Gordura Intra-Abdominal/efeitos dos fármacos , Fígado/efeitos dos fármacos , Prevalência , RatosRESUMO
Adipocyte-derived mediators contribute to chronic, diabetes-associated inflammation. We recently demonstrated, that heat shock protein 60 (Hsp60) is an effective inductor of inflammatory adipocyte activities. In the present study, we characterized the initial Hsp60 binding to adipocyte receptor structures. Analyses with preadipocytes and adipocytes from the murine 3T3-L1 line and with primary cultures from the New Zealand obese mouse, a model of human obesity, revealed comparable specific, dose-dependent and saturable Hsp60 binding, confirming the characteristics of a ligand-receptor interaction. Furthermore, we identified the N-terminal regions aa1-50 and aa91-110 of the Hsp60 molecule as relevant epitopes involved in binding to receptor structures on these cells. Our results demonstrate differentiation-independent conserved Hsp60 reactivity in permanent and primary adipocytes, strongly indicating that Hsp60 is an important regulator of inflammatory adipocyte activities.
Assuntos
Adipócitos/metabolismo , Chaperonina 60/metabolismo , Células 3T3-L1 , Animais , Chaperonina 60/genética , Endocitose , Humanos , Ligantes , Camundongos , Camundongos EndogâmicosRESUMO
[This corrects the article DOI: 10.1371/journal.pone.0172995.].
RESUMO
BACKGROUND: Ewing sarcoma (EwS) is a rare, aggressive solid tumor of childhood, adolescence and young adulthood associated with pathognomonic EWSR1-ETS fusion oncoproteins altering transcriptional regulation. Genome-wide association studies (GWAS) have identified 6 common germline susceptibility loci but have not investigated low-frequency inherited variants with minor allele frequencies below 5% due to limited genotyped cases of this rare tumor. METHODS: We investigated the contribution of rare and low-frequency variation to EwS susceptibility in the largest EwS genome-wide association study to date (733 EwS cases and 1,346 unaffected controls of European ancestry). RESULTS: We identified two low-frequency variants, rs112837127 and rs2296730, on chromosome 20 that were associated with EwS risk (OR = 0.186 and 2.038, respectively; P-value < 5×10-8) and located near previously reported common susceptibility loci. After adjusting for the most associated common variant at the locus, only rs112837127 remained a statistically significant independent signal (OR = 0.200, P-value = 5.84×10-8). CONCLUSIONS: These findings suggest rare variation residing on common haplotypes are important contributors to EwS risk. IMPACT: Motivate future targeted sequencing studies for a comprehensive evaluation of low-frequency and rare variation around common EwS susceptibility loci.
Assuntos
Loci Gênicos , Predisposição Genética para Doença , Variação Genética , Células Germinativas/metabolismo , Sarcoma de Ewing/genética , Estudo de Associação Genômica Ampla , Humanos , Desequilíbrio de Ligação/genética , Razão de Chances , Polimorfismo de Nucleotídeo Único/genéticaRESUMO
Recent studies suggest that insulin-like growth factor binding protein 2 (IGFBP-2) may protect against type 2 diabetes, but population-based human studies are scarce. We aimed to investigate the prospective association of circulating IGFBP-2 concentrations and of differential methylation in the IGFBP-2 gene with type 2 diabetes risk.