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1.
Cell ; 156(1-2): 343-58, 2014 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-24439387

RESUMEN

Genome-wide association studies have revealed numerous risk loci associated with diverse diseases. However, identification of disease-causing variants within association loci remains a major challenge. Divergence in gene expression due to cis-regulatory variants in noncoding regions is central to disease susceptibility. We show that integrative computational analysis of phylogenetic conservation with a complexity assessment of co-occurring transcription factor binding sites (TFBS) can identify cis-regulatory variants and elucidate their mechanistic role in disease. Analysis of established type 2 diabetes risk loci revealed a striking clustering of distinct homeobox TFBS. We identified the PRRX1 homeobox factor as a repressor of PPARG2 expression in adipose cells and demonstrate its adverse effect on lipid metabolism and systemic insulin sensitivity, dependent on the rs4684847 risk allele that triggers PRRX1 binding. Thus, cross-species conservation analysis at the level of co-occurring TFBS provides a valuable contribution to the translation of genetic association signals to disease-related molecular mechanisms.


Asunto(s)
Diabetes Mellitus Tipo 2/genética , Polimorfismo de Nucleótido Simple , Animales , Línea Celular , Células Cultivadas , Secuencia Conservada , Regulación de la Expresión Génica , Estudio de Asociación del Genoma Completo , Proteínas de Homeodominio/metabolismo , Humanos , Resistencia a la Insulina , PPAR gamma/genética , Secuencias Reguladoras de Ácidos Nucleicos , Factores de Transcripción/metabolismo
2.
Nature ; 613(7943): 355-364, 2023 01.
Artículo en Inglés | MEDLINE | ID: mdl-36599988

RESUMEN

DNA methylation is a fundamental epigenetic mark that governs gene expression and chromatin organization, thus providing a window into cellular identity and developmental processes1. Current datasets typically include only a fraction of methylation sites and are often based either on cell lines that underwent massive changes in culture or on tissues containing unspecified mixtures of cells2-5. Here we describe a human methylome atlas, based on deep whole-genome bisulfite sequencing, allowing fragment-level analysis across thousands of unique markers for 39 cell types sorted from 205 healthy tissue samples. Replicates of the same cell type are more than 99.5% identical, demonstrating the robustness of cell identity programmes to environmental perturbation. Unsupervised clustering of the atlas recapitulates key elements of tissue ontogeny and identifies methylation patterns retained since embryonic development. Loci uniquely unmethylated in an individual cell type often reside in transcriptional enhancers and contain DNA binding sites for tissue-specific transcriptional regulators. Uniquely hypermethylated loci are rare and are enriched for CpG islands, Polycomb targets and CTCF binding sites, suggesting a new role in shaping cell-type-specific chromatin looping. The atlas provides an essential resource for study of gene regulation and disease-associated genetic variants, and a wealth of potential tissue-specific biomarkers for use in liquid biopsies.


Asunto(s)
Células , Metilación de ADN , Epigénesis Genética , Epigenoma , Humanos , Línea Celular , Células/clasificación , Células/metabolismo , Cromatina/genética , Cromatina/metabolismo , Islas de CpG/genética , ADN/genética , ADN/metabolismo , Desarrollo Embrionario , Elementos de Facilitación Genéticos , Especificidad de Órganos , Proteínas del Grupo Polycomb/metabolismo , Secuenciación Completa del Genoma
3.
Int J Obes (Lond) ; 48(7): 934-940, 2024 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-38491191

RESUMEN

BACKGROUND/OBJECTIVE: Insulin resistance is more prominent in men than women. If this involves adipose tissue is unknown and was presently examined. SUBJECTS/METHODS: AdipoIR (in vivo adipose insulin resistance index) was measured in 2344 women and 787 men. In 259 of the women and 54 of the men, insulin induced inhibition of lipolysis (acylglycerol breakdown) and stimulation of lipogenesis (glucose conversion to acylglycerols) were determined in subcutaneous adipocytes; in addition, basal (spontaneous) lipolysis was also determined in the fat cells. In 234 women and 115 men, RNAseq expression of canonical insulin signal genes were measured in subcutaneous adipose tissue. Messenger RNA transcripts of the most discriminant genes were quantified in 175 women and 109 men. RESULTS: Men had higher AdipoIR values than women but only when obesity (body mass index 30 kg/m2 or more) was present (p < 0.0001). The latter sex dimorphism was found among physically active and sedentary people, in those with and without cardiometabolic disease and in people using nicotine or not (p = 0.0003 or less). In obesity, adipocyte insulin sensitivity (half maximum effective hormone concentration) and maximal antilipolytic effect were tenfold and 10% lower, respectively, in men than women (p = 0.005 or less). Basal rate of lipolysis was two times higher in men than women (p > 0.0001). Sensitivity and maximum effect of insulin on lipogenesis were similar in both sexes (p = 0.26 and p = 0.18, respectively). When corrected for multiple comparison only RNAseq expression of insulin receptor substrate 1 (IRS1) was lower in men than women (p < 0.0001). The mRNA transcript for IRS1 was 60% higher in women than men (p < 0.0001). CONCLUSIONS: In obesity, adipose tissue insulin resistance is more pronounced in men than in women. The mechanism involves less efficient insulin-mediated inhibition of adipocyte lipolysis, increased basal rate of lipolysis and decreased adipose expression of a key element of insulin signaling, IRS1.


Asunto(s)
Proteínas Sustrato del Receptor de Insulina , Resistencia a la Insulina , Lipólisis , Obesidad , Humanos , Femenino , Masculino , Lipólisis/fisiología , Resistencia a la Insulina/fisiología , Obesidad/metabolismo , Proteínas Sustrato del Receptor de Insulina/metabolismo , Proteínas Sustrato del Receptor de Insulina/genética , Adulto , Persona de Mediana Edad , Tejido Adiposo/metabolismo , Caracteres Sexuales , Adipocitos/metabolismo , Factores Sexuales
4.
Arterioscler Thromb Vasc Biol ; 43(6): 1054-1065, 2023 06.
Artículo en Inglés | MEDLINE | ID: mdl-37051928

RESUMEN

BACKGROUND: Adipose tissue insulin resistance is linked to altered plasma levels of triglycerides and HDL (high-density lipoprotein)-cholesterol. However, its degree of independence from liver resistance and different metabolic traits (lipolysis, lipogenesis) effected is not clear and was presently investigated. METHODS: In 3290 adult subjects, plasma levels of triglycerides and HDL-cholesterol were cross-sectionally measured and related to interindividual variations in measures of insulin resistance in the liver (homeostasis mode assessment of insulin resistance index) or adipose tissue (Adipo-IR index). In subgroups, insulin-induced antilipolysis and lipogenesis in isolated subcutaneous fat cells (n=578) were determined alongside global adipose tissue gene expression (n=132). RESULTS: Using linear regression, homeostasis mode assessment of insulin resistance and Adipo-IR strongly correlated with the plasma lipids explaining 33% of the variations in triglycerides. Together with other variables (age, sex, body mass index, cardiometabolic disorders, nicotine use, ethnicity, and physical activity) in multiple regression, homeostasis mode assessment of insulin resistance, and Adipo-IR each remained an important regressor for triglycerides and HDL-cholesterol (P<0.0001). In fat cells, half-maximum effective concentration but not maximum effect of insulin on antilipolysis and lipogenesis contributed independently to variations in triglycerides and HDL-cholesterol (P=0.001 or lower). This was linked to expression of the insulin receptor, insulin receptor substrate-1, and AKT serine/threonine kinase 2 in adipose tissue. CONCLUSIONS: Markers of insulin resistance in the liver and adipose tissue each associate strongly, and independently of each other, to elevated triglycerides and decreased HDL levels. At the fat cell, early insulin receptor signaling and sensitivity, but not maximum insulin action contributes to the variations in circulating triglycerides and HDL-cholesterol.


Asunto(s)
Dislipidemias , Resistencia a la Insulina , Adulto , Humanos , Receptor de Insulina , Obesidad/metabolismo , Tejido Adiposo/metabolismo , Triglicéridos , Insulina , HDL-Colesterol , Hígado/metabolismo , Dislipidemias/diagnóstico , Dislipidemias/genética
5.
Cardiovasc Diabetol ; 22(1): 84, 2023 04 12.
Artículo en Inglés | MEDLINE | ID: mdl-37046242

RESUMEN

AIM: Obesity is linked to cardiometabolic diseases, however non-obese individuals are also at risk for type 2 diabetes (T2D) and cardiovascular disease (CVD). White adipose tissue (WAT) is known to play a role in both T2D and CVD, but the contribution of WAT inflammatory status especially in non-obese patients with cardiometabolic diseases is less understood. Therefore, we aimed to find associations between WAT inflammatory status and cardiometabolic diseases in non-obese individuals. METHODS: In a population-based cohort containing non-obese healthy (n = 17), T2D (n = 16), CVD (n = 18), T2D + CVD (n = 19) individuals, seventeen different cytokines were measured in WAT and in circulation. In addition, 13-color flow cytometry profiling was employed to phenotype the immune cells. Human T cell line (Jurkat T cells) was stimulated by rCCL18, and conditioned media (CM) was added to the in vitro cultures of human adipocytes. Lipolysis was measured by glycerol release. Blocking antibodies against IFN-γ and TGF-ß were used in vitro to prove a role for these cytokines in CCL18-T-cell-adipocyte lipolysis regulation axis. RESULTS: In CVD, T2D and CVD + T2D groups, CCL18 and CD4+ T cells were upregulated significantly compared to healthy controls. WAT CCL18 secretion correlated with the amounts of WAT CD4+ T cells, which also highly expressed CCL18 receptors suggesting that WAT CD4+ T cells are responders to this chemokine. While direct addition of rCCL18 to mature adipocytes did not alter the adipocyte lipolysis, CM from CCL18-treated T cells increased glycerol release in in vitro cultures of adipocytes. IFN-γ and TGF-ß secretion was significantly induced in CM obtained from T cells treated with CCL18. Blocking these cytokines in CM, prevented CM-induced upregulation of adipocyte lipolysis. CONCLUSION: We suggest that in T2D and CVD, increased production of CCL18 recruits and activates CD4+ T cells to secrete IFN-γ and TGF-ß. This, in turn, promotes adipocyte lipolysis - a possible risk factor for cardiometabolic diseases.


Asunto(s)
Enfermedades Cardiovasculares , Diabetes Mellitus Tipo 2 , Humanos , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/metabolismo , Glicerol/metabolismo , Linfocitos T/metabolismo , Obesidad/metabolismo , Tejido Adiposo/metabolismo , Tejido Adiposo Blanco/metabolismo , Citocinas/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Linfocitos T CD4-Positivos/metabolismo , Enfermedades Cardiovasculares/diagnóstico , Enfermedades Cardiovasculares/metabolismo , Quimiocinas CC/metabolismo
6.
J Intern Med ; 291(5): 611-621, 2022 05.
Artículo en Inglés | MEDLINE | ID: mdl-34914848

RESUMEN

Recent technological developments have allowed determination of the age of fat cells and their lipids in adult humans. In contrast to prior views, this has demonstrated a high turnover rate of the fat cells (10%/year) and their unilocular lipid droplets (six times/10 years). Fat cell turnover is increased in obesity and when adipose tissue is composed of many but small adipocytes (hyperplasia, a benign adipose phenotype). While fat mass gain increases adipocyte number and size, only the latter is altered (decreased) after weight loss, which may facilitate weight regain. Fat cell lipid turnover is attenuated in subjects with excess body fat. In the subcutaneous region, this dysregulation occurs already in the overweight state while in the visceral depot, it is only observed in severe obesity. This may explain why the latter depot is particularly pernicious in the overweight/obese state as it allows for more rapid lipid fluxes between visceral fat and the liver. Adipose lipid turnover decreases during ageing due to impaired breakdown (lipolysis) of stored triglycerides. If this decline is not compensated by reduced adipocyte lipid uptake, bodyweight will increase over time. In concordance with this, low lipolysis rates are a risk factor for future weight gain and glucose intolerance. Adipose lipid turnover is also decreased in insulin resistance and certain forms of dyslipidemia. Altogether, adult human adipose tissue is in a highly dynamic state. Alterations in the turnover of fat cells and their lipids are therefore novel factors to consider in the pathophysiology of common metabolic disorders.


Asunto(s)
Resistencia a la Insulina , Enfermedades Metabólicas , Adipocitos/metabolismo , Tejido Adiposo/metabolismo , Humanos , Enfermedades Metabólicas/metabolismo , Obesidad/metabolismo , Sobrepeso/metabolismo , Triglicéridos/metabolismo
7.
J Intern Med ; 292(4): 667-678, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-35670497

RESUMEN

OBJECTIVE: Cross-sectional studies demonstrate that catecholamine stimulation of fat cell lipolysis is blunted in obesity. We investigated whether this defect persists after substantial weight loss has been induced by metabolic surgery, and whether it is related to the outcome. DESIGN/METHODS: Patients with obesity not able to successfully reduce body weight by conventional means (n = 126) were investigated before and 5 years after Roux-en-Y gastric bypass surgery (RYGB). They were compared with propensity-score matched subjects selected from a control group (n = 1017), and with the entire group after adjustment for age, sex, body mass index (BMI), fat cell volume and other clinical parameters. Catecholamine-stimulated lipolysis (glycerol release) was investigated in isolated fat cells using noradrenaline (natural hormone) or isoprenaline (synthetic beta-adrenoceptor agonist). RESULTS: Following RYGB, BMI was reduced from 39.9 (37.5-43.5) (median and interquartile range) to 29.5 (26.7-31.9) kg/m2 (p < 0.0001). The post-RYGB patients had about 50% lower lipolysis rates compared with the matched and total series of controls (p < 0.0005). Nordrenaline activation of lipolysis at baseline was associated with the RYGB effect; those with high lipolysis activation (upper tertile) lost 30%-45% more in body weight, BMI or fat mass than those with low (bottom tertile) initial lipolysis activation (p < 0.0007). CONCLUSION: Patients with obesity requiring metabolic surgery have impaired ability of catecholamines to stimulate lipolysis, which remains despite long-term normalization of body weight by RYGB. Furthermore, preoperative variations in the ability of catecholamines to activate lipolysis may predict the long-term reduction in body weight and fat mass.


Asunto(s)
Cirugía Bariátrica , Derivación Gástrica , Obesidad Mórbida , Índice de Masa Corporal , Peso Corporal , Catecolaminas/farmacología , Estudios Transversales , Glicerol , Hormonas , Humanos , Isoproterenol/farmacología , Lipólisis/fisiología , Norepinefrina , Obesidad/metabolismo , Obesidad/cirugía , Obesidad Mórbida/cirugía , Receptores Adrenérgicos/metabolismo , Resultado del Tratamiento
8.
Int J Obes (Lond) ; 46(6): 1196-1203, 2022 06.
Artículo en Inglés | MEDLINE | ID: mdl-35228658

RESUMEN

BACKGROUND/OBJECTIVE: The development of overweight/obesity associates with alterations in white adipose tissue (WAT) cellularity (fat cell size/number) and lipid metabolism, in particular lipolysis. If these changes differ between early/juvenile (EOO < 18 years of age) or late onset overweight/obesity (LOO) is unknown and was presently examined. SUBJECTS/METHODS: We included 439 subjects with validated information on body mass index (BMI) at 18 years of age. Using this information and current BMI, subjects were divided into never overweight/obese (BMI < 25 kg/m2), EOO and LOO. Adipocyte size, number, morphology (size in relation to body fat) and lipolysis were determined in subcutaneous abdominal WAT. Body composition and WAT distribution was assessed by dual-X-ray absorptiometry. RESULTS: Compared with never overweight/obese, EOO and LOO displayed larger WAT amounts in all examined depots, which in subcutaneous WAT was explained by a combination of increased size and number of fat cells in EOO and LOO. EOO had 40% larger subcutaneous fat mass than LOO (p < 0.0001). Visceral WAT mass, WAT morphology and lipolysis did not differ between EOO and LOO except for minor differences in men between the two obesity groups. On average, the increase in BMI per year was 57% higher in subjects with EOO compared to LOO (p < 0.0001). CONCLUSION: Early onset overweight/obesity causes a more rapid and pronounced accumulation of subcutaneous WAT than adult onset. However, fat mass expansion measures including WAT cellularity, morphology and fat cell lipolysis do not differ in an important way suggesting that similar mechanisms of WAT growth operate in EOO and LOO.


Asunto(s)
Sobrepeso , Grasa Subcutánea , Adipocitos/metabolismo , Tejido Adiposo/metabolismo , Tejido Adiposo Blanco/metabolismo , Adulto , Humanos , Masculino , Obesidad/metabolismo , Sobrepeso/metabolismo , Grasa Subcutánea/metabolismo
9.
Int J Obes (Lond) ; 45(12): 2675-2678, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34321614

RESUMEN

Insulin resistance of glucose utilization is fully restored following BMI normalization after bariatric surgery. We investigated if this also pertains to insulin-induced effects on fatty acid handling. Forty-three women with obesity (OB) were investigated before and 2 years after Roux-en-Y gastric by-pass when BMI was <30 kg/m2 (PO) and compared with 26 never obese women (NO). The Adipo-IR index was used as measure of insulin antilipolytic sensitivity. Changes (delta) in circulating glycerol and fatty acid levels during hyperinsulinemic euglycemic clamp represented the insulin maximum antilipolytic effect. Overall fatty acid utilization was reflected by delta fatty acids minus 3 × delta glycerol. Adipo-IR was higher in OB than in NO and PO (p < 0.0001), the latter two groups having similar values. Insulin lowered glycerol levels by about 70% in all groups, but delta glycerol was 30% larger in PO than in NO (p = 0.04). Delta adds and adds utilization were similar in all groups. We conclude that women with obesity, whose BMI is normalized after bariatric surgery, have improved maximum in vivo antilipolytic effect of insulin above expected in absolute but not relative terms as regards glycerol changes, while the handling of circulating fatty acids is changed to the normal state.


Asunto(s)
Cirugía Bariátrica/efectos adversos , Insulina/efectos adversos , Lipólisis/efectos de los fármacos , Adulto , Cirugía Bariátrica/estadística & datos numéricos , Glucemia/análisis , Glucemia/efectos de los fármacos , Glucemia/metabolismo , Femenino , Humanos , Hiperglucemia/tratamiento farmacológico , Hiperglucemia/fisiopatología , Insulina/uso terapéutico , Lipólisis/fisiología , Estudios Longitudinales , Persona de Mediana Edad
10.
Int J Obes (Lond) ; 44(12): 2436-2443, 2020 12.
Artículo en Inglés | MEDLINE | ID: mdl-32398753

RESUMEN

BACKGROUND: Obesity is a major factor behind insulin resistance. The validity of simple biochemical surrogate measures to estimate insulin resistance at the fat cell level is unclear. OBJECTIVE: To investigate if the surrogate measures HOMA-IR (glucose/insulin product) and Adipo-IR (fatty acids/insulin product) reflect insulin action on glucose/lipid metabolism in fat cells. DESIGN: Insulin-induced lipogenesis and lipolysis inhibition (antilipolysis) in subcutaneous fat cells were investigated for sensitivity (reflecting receptor-near events) and responsiveness (i.e., maximum action reflecting distal post-receptor events) in 363 subjects. Results were compared with log10 transformed values for HOMA-IR and Adipo-IR. RESULTS: Individually, the four measures of in vitro insulin action on fat cells correlated significantly (p < 0.0001) but weakly with each other (adjusted r2 0.05-0.23). HOMA-IR and Adipo-IR correlated strongly with each other (adjusted r2 = 0.81). Using Spearman or simple linear regression all in vitro measures except antilipolytic responsiveness expressed per lipid weight, correlated significantly with Adipo-IR or HOMA-IR (p values <0.0001). Similar relationships remained after combined correction for age, body mass index and sex. Together, the four in vitro measures explained 50% of the variability in HOMA-IR and ADIPO-IR (p < 0.0001). Receiver-operating characteristic analysis showed good sensitivity and specificity for Adipo-IR and HOMA-IR to detect combined insulin resistance of antilipolysis and lipogenesis in fat cells (area under the curve = 0.8). CONCLUSIONS: Insulin action at the receptor and post-receptor levels on lipolysis and lipogenesis in fat cells correlates significantly with Adipo-IR and HOMA-IR. Both surrogate measures give similar information about insulin resistance of glucose and lipid metabolism in fat cells.


Asunto(s)
Adipocitos/metabolismo , Resistencia a la Insulina , Insulina/metabolismo , Adiposidad , Adolescente , Adulto , Biomarcadores/metabolismo , Índice de Masa Corporal , Células Cultivadas , Femenino , Humanos , Lipogénesis , Lipólisis , Masculino , Persona de Mediana Edad , Adulto Joven
11.
Int J Obes (Lond) ; 44(2): 377-387, 2020 02.
Artículo en Inglés | MEDLINE | ID: mdl-31164724

RESUMEN

BACKGROUND: Transcriptome analysis of abdominal subcutaneous white adipose tissue (sWAT) has identified important obesity-associated disturbances. However, the relation between sWAT transcriptome and long-term future changes in body weight remains elusive. OBJECTIVE: To investigate sWAT transcriptome signatures before and after long-term weight changes and assess their predictive value for body weight changes. DESIGN: A total of 56 women were followed longitudinally and subdivided into weight-stable (WS, n = 25), weight-gaining (WG, n = 14) and weight-losing (WL, n = 17) groups between baseline and follow-up (13 ± 1 years). The fasting sWAT transcriptome was analyzed by gene microarray at baseline and follow-up. Key genes associated with weight changes were validated using quantitative real-time PCR. RESULTS: In total 285 transcripts exhibited difference (FDR < 30%) in expression fold change over time between WL and WS women. WL women displayed decreased pro-inflammatory (NLRP3) but increased insulin-response gene (FASN and GLUT4) expression over time. In comparison, 461 transcripts displayed difference in expression fold change over time between WG and WS women (P < 0.05). Genes involved in autophagic processes (CDK5, SQSTM1 and FBXL2) were generally upregulated in WG women. At baseline, 307 and 302 transcripts were differentially expressed (FDR < 30%) in WL and WG women, respectively, when independently compared against WS women. Baseline expression of adipogenic and lipogenic genes (PPARG, IRS2 and HACD2) was lower, while pro-fibrotic (COL6A1) was higher, in WL than WS women; whereas protein processing genes were lower expressed in WG than in WS women. CONCLUSION: In adult women, long-term body weight change associates with altered sWAT transcriptome. Expression of genes associated with inflammation, insulin response, adipogenesis and lipogenesis are linked to weight loss. However, other pathways such as autophagy not only associate but also predict future weight gain suggesting that intrinsic factors in sWAT impact tissue expansion.


Asunto(s)
Peso Corporal , Obesidad , Grasa Subcutánea Abdominal/metabolismo , Transcriptoma/genética , Adulto , Peso Corporal/genética , Peso Corporal/fisiología , Femenino , Humanos , Inflamación/genética , Lipogénesis/genética , Persona de Mediana Edad , Obesidad/genética , Obesidad/metabolismo , Estudios Prospectivos
12.
Nature ; 507(7493): 462-70, 2014 Mar 27.
Artículo en Inglés | MEDLINE | ID: mdl-24670764

RESUMEN

Regulated transcription controls the diversity, developmental pathways and spatial organization of the hundreds of cell types that make up a mammal. Using single-molecule cDNA sequencing, we mapped transcription start sites (TSSs) and their usage in human and mouse primary cells, cell lines and tissues to produce a comprehensive overview of mammalian gene expression across the human body. We find that few genes are truly 'housekeeping', whereas many mammalian promoters are composite entities composed of several closely separated TSSs, with independent cell-type-specific expression profiles. TSSs specific to different cell types evolve at different rates, whereas promoters of broadly expressed genes are the most conserved. Promoter-based expression analysis reveals key transcription factors defining cell states and links them to binding-site motifs. The functions of identified novel transcripts can be predicted by coexpression and sample ontology enrichment analyses. The functional annotation of the mammalian genome 5 (FANTOM5) project provides comprehensive expression profiles and functional annotation of mammalian cell-type-specific transcriptomes with wide applications in biomedical research.


Asunto(s)
Atlas como Asunto , Anotación de Secuencia Molecular , Regiones Promotoras Genéticas/genética , Transcriptoma/genética , Animales , Línea Celular , Células Cultivadas , Análisis por Conglomerados , Secuencia Conservada/genética , Regulación de la Expresión Génica/genética , Redes Reguladoras de Genes/genética , Genes Esenciales/genética , Genoma/genética , Humanos , Ratones , Sistemas de Lectura Abierta/genética , Especificidad de Órganos , ARN Mensajero/análisis , ARN Mensajero/genética , Factores de Transcripción/metabolismo , Sitio de Iniciación de la Transcripción , Transcripción Genética/genética
13.
Nucleic Acids Res ; 45(6): 3266-3279, 2017 04 07.
Artículo en Inglés | MEDLINE | ID: mdl-28334807

RESUMEN

Genome-wide association studies identified numerous disease risk loci. Delineating molecular mechanisms influenced by cis-regulatory variants is essential to understand gene regulation and ultimately disease pathophysiology. Combining bioinformatics and public domain chromatin information with quantitative proteomics supports prediction of cis-regulatory variants and enabled identification of allele-dependent binding of both, transcription factors and coregulators at the type 2 diabetes associated PPARG locus. We found rs7647481A nonrisk allele binding of Yin Yang 1 (YY1), confirmed by allele-specific chromatin immunoprecipitation in primary adipocytes. Quantitative proteomics also found the coregulator RING1 and YY1 binding protein (RYBP) whose mRNA levels correlate with improved insulin sensitivity in primary adipose cells carrying the rs7647481A nonrisk allele. Our findings support a concept with diverse cis-regulatory variants contributing to disease pathophysiology at one locus. Proteome-wide identification of both, transcription factors and coregulators, can profoundly improve understanding of mechanisms underlying genetic associations.


Asunto(s)
Alelos , PPAR gamma/genética , Proteómica , Elementos Reguladores de la Transcripción , Tejido Adiposo/metabolismo , Animales , Células Cultivadas , Proteínas de Unión al ADN/metabolismo , Sitios Genéticos , Variación Genética , Humanos , Resistencia a la Insulina/genética , Ratones , Ratas , Factores de Transcripción/metabolismo , Transcripción Genética , Factor de Transcripción YY1/metabolismo
14.
Diabetologia ; 61(5): 1112-1123, 2018 05.
Artículo en Inglés | MEDLINE | ID: mdl-29487953

RESUMEN

AIMS/HYPOTHESIS: By genome-wide association meta-analysis, 17 genetic loci associated with fasting serum insulin (FSI), a marker of systemic insulin resistance, have been identified. To define potential culprit genes in these loci, in a cross-sectional study we analysed white adipose tissue (WAT) expression of 120 genes in these loci in relation to systemic and adipose tissue variables, and functionally evaluated genes demonstrating genotype-specific expression in WAT (eQTLs). METHODS: Abdominal subcutaneous adipose tissue biopsies were obtained from 114 women. Basal lipolytic activity was measured as glycerol release from adipose tissue explants. Adipocytes were isolated and insulin-stimulated incorporation of radiolabelled glucose into lipids was used to quantify adipocyte insulin sensitivity. Small interfering RNA-mediated knockout in human mesenchymal stem cells was used for functional evaluation of genes. RESULTS: Adipose expression of 48 of the studied candidate genes associated significantly with FSI, whereas expression of 24, 17 and 2 genes, respectively, associated with adipocyte insulin sensitivity, lipolysis and/or WAT morphology (i.e. fat cell size relative to total body fat mass). Four genetic loci contained eQTLs. In one chromosome 4 locus (rs3822072), the FSI-increasing allele associated with lower FAM13A expression and FAM13A expression associated with a beneficial metabolic profile including decreased WAT lipolysis (regression coefficient, R = -0.50, p = 5.6 × 10-7). Knockdown of FAM13A increased lipolysis by ~1.5-fold and the expression of LIPE (encoding hormone-sensitive lipase, a rate-limiting enzyme in lipolysis). At the chromosome 7 locus (rs1167800), the FSI-increasing allele associated with lower POM121C expression. Consistent with an insulin-sensitising function, POM121C expression associated with systemic insulin sensitivity (R = -0.22, p = 2.0 × 10-2), adipocyte insulin sensitivity (R = 0.28, p = 3.4 × 10-3) and adipose hyperplasia (R = -0.29, p = 2.6 × 10-2). POM121C knockdown decreased expression of all adipocyte-specific markers by 25-50%, suggesting that POM121C is necessary for adipogenesis. CONCLUSIONS/INTERPRETATION: Gene expression and adipocyte functional studies support the notion that FAM13A and POM121C control adipocyte lipolysis and adipogenesis, respectively, and might thereby be involved in genetic control of systemic insulin sensitivity.


Asunto(s)
Proteínas Activadoras de GTPasa/genética , Estudio de Asociación del Genoma Completo , Insulina/metabolismo , Glicoproteínas de Membrana/genética , Adipocitos/metabolismo , Adipogénesis , Tejido Adiposo/metabolismo , Adiposidad , Adulto , Ayuno , Femenino , Estudios de Seguimiento , Genotipo , Glucosa/metabolismo , Humanos , Resistencia a la Insulina , Lipólisis , Persona de Mediana Edad , Obesidad/metabolismo , Análisis de Secuencia por Matrices de Oligonucleótidos , Fenotipo , Sitios de Carácter Cuantitativo , Suecia
15.
Int J Obes (Lond) ; 42(12): 2047-2056, 2018 12.
Artículo en Inglés | MEDLINE | ID: mdl-29453465

RESUMEN

BACKGROUND: Adipokines are peptides secreted from white adipose tissue (WAT), which have been linked to WAT dysfunction and metabolic complications of obesity. We set out to identify novel adipokines in subcutaneous WAT (sWAT) linked to insulin resistance (IR). METHODS: Gene expression was determined by microarray and qPCR in obese and non-obese subjects with varying degree of IR. WAT-secreted and circulating protein levels were measured by ELISA. RESULTS: In sWAT of 80 obese women discordant for IR, 44 genes encoding potential adipose-secreted proteins were differentially expressed. Among these, merely two proteins, S100A4 and MXRA5 were released from sWAT in a time-dependent manner (criterion for true adipokines) but only the circulating levels of S100A4 were higher in IR. In two additional cohorts (n = 29 and n = 56), sWAT S100A4 secretion was positively and BMI-independently associated with IR (determined by clamp or HOMA-IR), ATP-III risk score and adipocyte size (hypertrophy). In non-obese (n = 20) and obese subjects before and after bariatric surgery (n = 21), circulating and sWAT-secreted levels were highest in the obese and normalized following weight loss. Serum S100A4 concentrations were higher in subjects with type 2 diabetes. S100A4 sWAT expression associated positively with genes involved in inflammation/extracellular matrix formation and inversely with genes in metabolic pathways. Although S100A4 was expressed in both stromal cells and adipocytes, only the expression in adipocytes associated with BMI. CONCLUSIONS: S100A4 is a novel adipokine associated with IR and sWAT inflammation/adipocyte hypertrophy independently of BMI. Its value as a circulating marker for dysfunctional WAT and IR needs to be validated in larger cohorts.


Asunto(s)
Adipoquinas/metabolismo , Tejido Adiposo Blanco/metabolismo , Resistencia a la Insulina/fisiología , Obesidad/metabolismo , Proteína de Unión al Calcio S100A4/metabolismo , Adipoquinas/sangre , Tejido Adiposo Blanco/química , Adulto , Biomarcadores , Estudios de Cohortes , Femenino , Humanos , Inflamación/metabolismo , Masculino , Persona de Mediana Edad , Obesidad/sangre , Obesidad/epidemiología , Proteína de Unión al Calcio S100A4/sangre
17.
Stem Cells ; 35(7): 1799-1814, 2017 07.
Artículo en Inglés | MEDLINE | ID: mdl-28470788

RESUMEN

White adipose tissue (WAT) expands in part through adipogenesis, a process involving fat cell generation and fatty acid (FA) storage into triglycerides (TGs). Several findings suggest that inter-individual and regional variations in adipogenesis are linked to metabolic complications. We aimed to identify cellular markers that define human adipocyte progenitors (APs) with pronounced adipogenic/TG storage ability. Using an unbiased single cell screen of passaged human adipose-derived stromal cells (hADSCs), we identified cell clones with similar proliferation rates but discordant capabilities to undergo adipogenic differentiation. Transcriptomic analyses prior to induction of differentiation showed that adipogenic clones displayed a significantly higher expression of CD36, encoding the scavenger receptor CD36. CD36+ hADSCs, in comparison with CD36-cells, displayed almost complete adipogenic differentiation while CD36 RNAi attenuated lipid accumulation. Similar findings were observed in primary CD45-/CD34+/CD31-APs isolated from human WAT where the subpopulation of MSCA1+/CD36+ cells displayed a significantly higher differentiation degree/TG storage capacity than MSCA1+/CD36-cells. Functional analyses in vitro and ex vivo confirmed that CD36 conferred APs an increased capacity to take up FAs thereby facilitating terminal differentiation. Among primary APs from subcutaneous femoral, abdominal and visceral human WAT, the fraction of CD36+ cells was significantly higher in depots associated with higher adipogenesis and reduced metabolic risk (i.e., femoral WAT). We conclude that CD36 marks APs with pronounced adipogenic potential, most probably by facilitating lipid uptake. This may be of value in developing human adipocyte cell clones and possibly in linking regional variations in adipogenesis to metabolic phenotype. Stem Cells 2017;35:1799-1814.


Asunto(s)
Adipocitos Blancos/metabolismo , Tejido Adiposo Blanco/metabolismo , Antígenos CD36/genética , Células Madre/metabolismo , Transcriptoma , Triglicéridos/metabolismo , Adipocitos Blancos/citología , Adipogénesis/genética , Tejido Adiposo Blanco/citología , Adulto , Antígenos CD34/genética , Antígenos CD34/metabolismo , Antígenos de Superficie/genética , Antígenos de Superficie/metabolismo , Transporte Biológico , Antígenos CD36/antagonistas & inhibidores , Antígenos CD36/metabolismo , Diferenciación Celular , Proliferación Celular , Femenino , Perfilación de la Expresión Génica , Humanos , Antígenos Comunes de Leucocito/genética , Antígenos Comunes de Leucocito/metabolismo , Persona de Mediana Edad , Cultivo Primario de Células , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/metabolismo , Análisis de la Célula Individual , Células Madre/citología
18.
Diabetes Obes Metab ; 20(10): 2416-2425, 2018 10.
Artículo en Inglés | MEDLINE | ID: mdl-29862627

RESUMEN

AIM: To examine the cell membrane transporters involved in mediating the antilipolytic effect of biguanides in human fat cells. MATERIALS AND METHODS: Gene expression of biguanide transporters was mapped in human subcutaneous adipose tissue and in adipocytes before and after differentiation. Those expressed in mature fat cells were knocked down by RNA interference (RNAi) and the antilipolytic effects of metformin and two novel, highly potent biguanides, NT1014 and NT1044, were examined. RESULTS: Analysis of the transporter affinity of biguanides in HEK293 cells overexpressing individual transporters showed that NT1014 and NT1044 had >10 times higher affinity than metformin. Animal studies showed that NT1014 was >5 times more potent than metformin in lowering plasma glucose in mice. In human fat cells, the novel biguanides displayed higher AMP-activated protein kinase activation and antilipolytic efficacy than metformin. Five transporters, organic cation transporter (OCT)1 (SLC22A1), organic cation transporter novel type 1 (OCTN1; SLC22A4), OCT3 (SLC22A3), plasma membrane monoamine transporter (PMAT; SLC29A4) and multidrug and toxin extrusion transporter (MATE1; SLC47A1), were detectable in fat cells but only OCT3, PMAT and MATE1 increased during adipogenesis in vitro and were enriched in fat cells compared with other adipose cell types. Gene knockdown by RNAi showed that MATE1 and PMAT reduction attenuated the antilipolytic effect of metformin but only PMAT knockdown decreased the effect of all three biguanides. CONCLUSIONS: While human fat cells primarily express three biguanide transporters, our data suggest that PMAT is the primary target for development of fat cell-specific antilipolytic biguanides with high sensitivity and potency.


Asunto(s)
Adipocitos/metabolismo , Biguanidas/metabolismo , Lipólisis/genética , Proteínas de Transporte de Catión Orgánico/genética , Proteínas de Transporte de Catión Orgánico/metabolismo , Adipocitos/patología , Adulto , Anciano , Animales , Biguanidas/uso terapéutico , Transporte Biológico/genética , Células Cultivadas , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patología , Femenino , Regulación de la Expresión Génica , Células HEK293 , Humanos , Masculino , Ratones , Ratones Endogámicos C57BL , Persona de Mediana Edad , Distribución Tisular
19.
Arterioscler Thromb Vasc Biol ; 37(9): 1782-1787, 2017 09.
Artículo en Inglés | MEDLINE | ID: mdl-28663255

RESUMEN

OBJECTIVE: Fatty acids released via fat cell lipolysis can affect circulating lipid levels. However, the contribution of different lipolysis measures in adipose tissue is unknown and was presently examined in isolated subcutaneous adipocytes. APPROACH AND RESULTS: One thousand and sixty-six men and women were examined for lipolysis regulation in subcutaneous abdominal fat cells. Results were compared with fasting plasma levels of total cholesterol, high-density lipoprotein (HDL) cholesterol (HDL-C) and triglycerides. Spontaneous (basal) lipolysis and the effects of the major hormones stimulating (catecholamines and natriuretic peptides) and inhibiting lipolysis (insulin) were examined. Several statistically significant (P<0.0001) correlations between the different lipolysis parameters and plasma lipids were observed. However, physiologically relevant correlations (adjusted r2≥0.05) were only evident between basal or insulin-inhibited lipolysis and plasma triglycerides or HDL-C. Together, these lipolysis measures explained 14% of the variation in triglycerides or HDL-C, respectively. In comparison, a combination of established factors associated with variations in plasma lipids, that is, age; body mass index; waist circumference; waist-to-hip ratio; sex; nicotine use; fat cell volume; and pharmacotherapy against diabetes mellitus; hypertension; or hyperlipidemia explained 17% and 28%, respectively, of the variations in plasma triglycerides and HDL-C. CONCLUSIONS: Subcutaneous fat cell lipolysis is an important independent contributor to interindividual variations in plasma lipids. High spontaneous lipolysis activity and resistance to the antilipolytic effect of insulin associate with elevated triglyceride and low HDL-C concentrations. Thus, although several other factors also play a role, subcutaneous adipose tissue may have a causal influence on dyslipidemia.


Asunto(s)
Adipocitos Blancos/metabolismo , Lípidos/sangre , Lipólisis , Grasa Subcutánea Abdominal/metabolismo , Adipocitos Blancos/efectos de los fármacos , Adolescente , Adulto , Anciano , Antihipertensivos/uso terapéutico , Biomarcadores/sangre , HDL-Colesterol/sangre , Femenino , Humanos , Hipoglucemiantes/uso terapéutico , Hipolipemiantes/uso terapéutico , Lipólisis/efectos de los fármacos , Masculino , Persona de Mediana Edad , Grasa Subcutánea Abdominal/efectos de los fármacos , Triglicéridos/sangre , Adulto Joven
20.
Proc Natl Acad Sci U S A ; 112(14): 4363-8, 2015 Apr 07.
Artículo en Inglés | MEDLINE | ID: mdl-25831505

RESUMEN

Genome-wide association studies have implicated PLEXIN D1 (PLXND1) in body fat distribution and type 2 diabetes. However, a role for PLXND1 in regional adiposity and insulin resistance is unknown. Here we use in vivo imaging and genetic analysis in zebrafish to show that Plxnd1 regulates body fat distribution and insulin sensitivity. Plxnd1 deficiency in zebrafish induced hyperplastic morphology in visceral adipose tissue (VAT) and reduced lipid storage. In contrast, subcutaneous adipose tissue (SAT) growth and morphology were unaffected, resulting in altered body fat distribution and a reduced VAT:SAT ratio in zebrafish. A VAT-specific role for Plxnd1 appeared conserved in humans, as PLXND1 mRNA was positively associated with hypertrophic morphology in VAT, but not SAT. In zebrafish plxnd1 mutants, the effect on VAT morphology and body fat distribution was dependent on induction of the extracellular matrix protein collagen type V alpha 1 (col5a1). Furthermore, after high-fat feeding, zebrafish plxnd1 mutant VAT was resistant to expansion, and excess lipid was disproportionately deposited in SAT, leading to an even greater exacerbation of altered body fat distribution. Plxnd1-deficient zebrafish were protected from high-fat-diet-induced insulin resistance, and human VAT PLXND1 mRNA was positively associated with type 2 diabetes, suggesting a conserved role for PLXND1 in insulin sensitivity. Together, our findings identify Plxnd1 as a novel regulator of VAT growth, body fat distribution, and insulin sensitivity in both zebrafish and humans.


Asunto(s)
Moléculas de Adhesión Celular Neuronal/fisiología , Colágeno Tipo V/biosíntesis , Insulina/metabolismo , Grasa Intraabdominal/patología , Glicoproteínas de Membrana/fisiología , Proteínas del Tejido Nervioso/fisiología , Animales , Composición Corporal , Proliferación Celular , Células Endoteliales/citología , Matriz Extracelular/metabolismo , Femenino , Regulación de la Expresión Génica , Humanos , Péptidos y Proteínas de Señalización Intracelular , Lípidos/química , Ratones , Mutación , Obesidad , ARN Mensajero/metabolismo , Transducción de Señal , Pez Cebra
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