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1.
Cell Rep ; 43(5): 114240, 2024 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-38753486

RESUMEN

Adipose tissue remodeling and dysfunction, characterized by elevated inflammation and insulin resistance, play a central role in obesity-related development of type 2 diabetes (T2D) and cardiovascular diseases. Long intergenic non-coding RNAs (lincRNAs) are important regulators of cellular functions. Here, we describe the functions of linc-ADAIN (adipose anti-inflammatory), an adipose lincRNA that is downregulated in white adipose tissue of obese humans. We demonstrate that linc-ADAIN knockdown (KD) increases KLF5 and interleukin-8 (IL-8) mRNA stability and translation by interacting with IGF2BP2. Upregulation of KLF5 and IL-8, via linc-ADAIN KD, leads to an enhanced adipogenic program and adipose tissue inflammation, mirroring the obese state, in vitro and in vivo. KD of linc-ADAIN in human adipose stromal cell (ASC) hTERT adipocytes implanted into mice increases adipocyte size and macrophage infiltration compared to implanted control adipocytes, mimicking hallmark features of obesity-induced adipose tissue remodeling. linc-ADAIN is an anti-inflammatory lincRNA that limits adipose tissue expansion and lipid storage.


Asunto(s)
Adipogénesis , Interleucina-8 , Factores de Transcripción de Tipo Kruppel , Estabilidad del ARN , ARN Largo no Codificante , Humanos , ARN Largo no Codificante/genética , ARN Largo no Codificante/metabolismo , Factores de Transcripción de Tipo Kruppel/metabolismo , Factores de Transcripción de Tipo Kruppel/genética , Adipogénesis/genética , Animales , Estabilidad del ARN/genética , Interleucina-8/metabolismo , Interleucina-8/genética , Ratones , Proteínas de Unión al ARN/metabolismo , Proteínas de Unión al ARN/genética , Adipocitos/metabolismo , Tejido Adiposo/metabolismo , Obesidad/metabolismo , Obesidad/genética , Obesidad/patología , ARN Mensajero/metabolismo , ARN Mensajero/genética , Masculino , Inflamación/patología , Inflamación/genética , Inflamación/metabolismo
2.
Obesity (Silver Spring) ; 32(1): 70-79, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-37929774

RESUMEN

OBJECTIVE: This study investigated remodeling of cellular metabolism and structures during browning of primary human adipocytes derived from both visceral and subcutaneous adipose tissues. Effects of glucocorticoids on the browning were also assessed. METHODS: Differentiated omental and subcutaneous human adipocytes were treated with rosiglitazone, with or without dexamethasone, and expression levels of brite adipocyte markers, lipolysis, and lipid droplet and mitochondrial structures were examined. RESULTS: Both omental and subcutaneous adipocytes acquired brite phenotypes upon peroxisome proliferator-activated receptor-γ agonist treatment, and dexamethasone tended to enhance the remodeling. Although rosiglitazone increased lipolysis during treatment, brite adipocytes exhibited lower basal lipolytic rates and enhanced responses to ß-adrenergic agonists or atrial natriuretic peptide. Transcriptome analysis identified induction of both breakdown and biosynthesis of lipids in brite adipocytes. After 60+ days in culture, lipid droplet size increased to ~50 microns, becoming almost unilocular in control adipocytes, and after browning, they acquired paucilocular morphology, clusters of small lipid droplets (1-2 micron) surrounded by mitochondria appearing on the periphery of the central large one. CONCLUSIONS: Metabolic and structural remodeling during browning of primary human adipocytes is similar to previous findings in human adipocytes in vivo, supporting their uses for mechanical studies investigating browning with translational relevance.


Asunto(s)
Adipocitos , Grasa Subcutánea , Humanos , Rosiglitazona/farmacología , Rosiglitazona/metabolismo , Adipocitos/metabolismo , Grasa Subcutánea/metabolismo , Lipólisis , Dexametasona
3.
Curr Opin Genet Dev ; 81: 102079, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-37406429

RESUMEN

Body fat is stored in anatomically distinct adipose depots that vary in their cell composition and play specialized roles in systemic metabolic homeostasis via secreted products. Their local effects on nearby tissues (e.g. the gut and visceral adipose tissues) are increasingly recognized and this local crosstalk is being elucidated. The major subcutaneous fat depots, abdominal and gluteal-femoral, exert opposite effects on the risk of metabolic disease. The pace of research into developmental, sex, and genetic determinants of human adipose depot growth and function is rapidly accelerating, providing insight into the pathogenesis of metabolic dysfunction in persons with obesity.


Asunto(s)
Tejido Adiposo , Obesidad , Humanos , Obesidad/metabolismo , Tejido Adiposo/patología , Adiposidad , Grasa Subcutánea/metabolismo , Grasa Subcutánea/patología , Grasa Intraabdominal/metabolismo , Grasa Intraabdominal/patología
4.
Exp Biol Med (Maywood) ; 248(3): 209-216, 2023 02.
Artículo en Inglés | MEDLINE | ID: mdl-36544403

RESUMEN

Dietary supplementation with l-arginine has been reported to reduce white fat mass in diet-induced obese rats and in obese humans. This study was conducted to test the hypothesis that the arginine treatment regulates glucose and fatty acid metabolism in insulin-sensitive tissues. Male Sprague-Dawley rats (4-week-old) were fed either low- or high-fat diets for 15 weeks (n = 16/diet). Thereafter, lean or obese rats were fed their respective diets and received drinking water containing either 1.51% l-arginine-HCl or 2.55% alanine (isonitrogenous control) (n = 8/treatment group). After 12 weeks of treatment, rats were euthanized and tissue samples were collected for biochemical assays. High-fat feeding increased the size of adipocytes isolated from retroperitoneal (RP) adipose tissue, while arginine treatment reduced their size. The total number of adipocytes in the adipose tissue did not differ among the four groups of rats. Glucose oxidation in extensor digitorum longus (EDL) muscle, soleus muscle, and RP adipose tissue were reduced in response to high-fat feeding. On the contrary, oleic acid oxidation in RP adipose tissue was enhanced in rats fed the high-fat diet. Arginine treatment stimulated both glucose and oleic acid oxidation in EDL and soleus muscles, while having no effect on glucose oxidation, oleic acid oxidation, or basal lipolysis per 106 adipocytes in RP adipose tissue. Collectively, these results indicate that oral supplementation with arginine to diet-induced obese rats promoted the oxidation of energy substrates in skeletal muscle, thereby reducing white fat in the body.


Asunto(s)
Tejido Adiposo , Ácido Oléico , Humanos , Ratas , Masculino , Animales , Ácido Oléico/metabolismo , Ácido Oléico/farmacología , Ratas Sprague-Dawley , Tejido Adiposo/metabolismo , Obesidad/metabolismo , Músculo Esquelético/metabolismo , Arginina/metabolismo , Glucosa/metabolismo , Dieta Alta en Grasa , Suplementos Dietéticos
5.
Metabolism ; 137: 155331, 2022 12.
Artículo en Inglés | MEDLINE | ID: mdl-36228741

RESUMEN

BACKGROUND: The triglyceride (TG) transfer activity of microsomal triglyceride transfer protein (MTP) is essential for lipoprotein assembly in the liver and intestine; however, its function in adipose tissue, which does not assemble lipoproteins, is unknown. Here we have elucidated the function of MTP in adipocytes. APPROACH AND RESULTS: We demonstrated that MTP is present on lipid droplets in human adipocytes. Adipose-specific MTP deficient (A-Mttp-/-) male and female mice fed an obesogenic diet gained less weight than Mttpf/f mice, had less fat mass, smaller adipocytes and were insulin sensitive. A-Mttp-/- mice showed higher energy expenditure than Mttpf/f mice. During a cold challenge, A-Mttp-/- mice maintained higher body temperature by mobilizing more fatty acids. Biochemical studies indicated that MTP deficiency de-repressed adipose triglyceride lipase (ATGL) activity and increased TG lipolysis. Both wild type MTP and mutant MTP deficient in TG transfer activity interacted with and inhibited ATGL activity. Thus, the TG transfer activity of MTP is not required for ATGL inhibition. C-terminally truncated ATGL that retains its lipase activity interacted less efficiently than full-length ATGL. CONCLUSION: Our findings demonstrate that adipose-specific MTP deficiency increases ATGL-mediated TG lipolysis and enhances energy expenditure, thereby resisting diet-induced obesity. We speculate that the regulatory function of MTP involving protein-protein interactions might have evolved before the acquisition of TG transfer activity in vertebrates. Adipose-specific inhibition of MTP-ATGL interactions may ameliorate obesity while avoiding the adverse effects associated with inhibition of the lipid transfer activity of MTP.


Asunto(s)
Lipasa , Lipólisis , Animales , Femenino , Humanos , Masculino , Ratones , Adipocitos/metabolismo , Lipasa/metabolismo , Lípidos/farmacología , Obesidad/metabolismo
6.
Obesity (Silver Spring) ; 29(3): 562-568, 2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-33624437

RESUMEN

OBJECTIVE: The purpose of this study was to investigate the effects of vitamin D on adipokine expression and inflammation in human adipose tissues and adipocytes and evaluate the molecular mechanisms involved. METHODS: Omental and abdominal subcutaneous human adipose tissues were treated with 1,25-dihydroxyvitamin D3 (1,25(OH)2 D3 ), and adipokine levels were measured. Vitamin D effects were measured with or without dexamethasone because glucocorticoids are known to affect vitamin D actions. Using RNA interference, we examined whether the vitamin D receptor (VDR) mediated vitamin D actions on adipokine expression and inflammatory signaling pathways in human adipocytes. RESULTS: mRNA levels and secretion of leptin and IL-6 were suppressed by 1,25(OH)2 D3 in omental adipose tissues. Cotreatment with dexamethasone did not affect these inhibitory actions but partially blocked CYP24A1 induction. Similar results were observed in the subcutaneous depot. In addition, 1,25(OH)2 D3 suppressed leptin and IL-6 expression as well as nuclear factor-κB and extracellular signal-regulated kinase-1/2 phosphorylation in human adipocytes. Adipokine expression also was decreased by 25-hydroxyvitamin D3 (25(OH)D3 ), but not vitamin D3 . Knockdown of VDR increased the inflammatory signaling activity in the control condition and blocked the inhibitory effects of 1,25(OH)2 D3 on adipokine and inflammatory signaling pathways. CONCLUSION: Vitamin D acts through VDR to inhibit inflammatory pathways and adipokine expression in human adipocytes. Increasing vitamin D status may ameliorate obesity-associated metabolic complications by decreasing adipose tissue inflammation.


Asunto(s)
Adipocitos/efectos de los fármacos , Adipoquinas/metabolismo , Mediadores de Inflamación/metabolismo , Receptores de Calcitriol/fisiología , Vitamina D/análogos & derivados , Adipocitos/metabolismo , Tejido Adiposo/efectos de los fármacos , Tejido Adiposo/metabolismo , Adulto , Anciano , Células Cultivadas , Femenino , Humanos , Inflamación/genética , Inflamación/metabolismo , Inflamación/prevención & control , Masculino , Persona de Mediana Edad , Cultivo Primario de Células , Receptores de Calcitriol/metabolismo , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética , Vitamina D/farmacología
7.
Elife ; 92020 12 15.
Artículo en Inglés | MEDLINE | ID: mdl-33320092

RESUMEN

It has been known adipocytes increase p53 expression and activity in obesity, however, only canonical p53 functions (i.e. senescence and apoptosis) are attributed to inflammation-associated metabolic phenotypes. Whether or not p53 is directly involved in mature adipocyte metabolic regulation remains unclear. Here we show p53 protein expression can be up-regulated in adipocytes by nutrient starvation without activating cell senescence, apoptosis, or a death-related p53 canonical pathway. Inducing the loss of p53 in mature adipocytes significantly reprograms energy metabolism and this effect is primarily mediated through a AMP-activated protein kinase (AMPK) pathway and a novel downstream transcriptional target, lysosomal acid lipase (LAL). The pathophysiological relevance is further demonstrated in a conditional and adipocyte-specific p53 knockout mouse model. Overall, these data support a non-canonical p53 function in the regulation of adipocyte energy homeostasis and indicate that the dysregulation of this pathway may be involved in developing metabolic dysfunction in obesity.


Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Adipocitos/metabolismo , Metabolismo Energético/fisiología , Obesidad/patología , Proteína p53 Supresora de Tumor/metabolismo , Células 3T3-L1 , Animales , Sistemas CRISPR-Cas/genética , Línea Celular , Reprogramación Celular , Edición Génica/métodos , Glucosa/metabolismo , Metabolismo de los Lípidos/fisiología , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Interferencia de ARN , ARN Interferente Pequeño/genética , Inanición/metabolismo , Esterol Esterasa/metabolismo , Proteína p53 Supresora de Tumor/genética
8.
Cell ; 183(3): 684-701.e14, 2020 10 29.
Artículo en Inglés | MEDLINE | ID: mdl-33058756

RESUMEN

Positive selection in Europeans at the 2q21.3 locus harboring the lactase gene has been attributed to selection for the ability of adults to digest milk to survive famine in ancient times. However, the 2q21.3 locus is also associated with obesity and type 2 diabetes in humans, raising the possibility that additional genetic elements in the locus may have contributed to evolutionary adaptation to famine by promoting energy storage, but which now confer susceptibility to metabolic diseases. We show here that the miR-128-1 microRNA, located at the center of the positively selected locus, represents a crucial metabolic regulator in mammals. Antisense targeting and genetic ablation of miR-128-1 in mouse metabolic disease models result in increased energy expenditure and amelioration of high-fat-diet-induced obesity and markedly improved glucose tolerance. A thrifty phenotype connected to miR-128-1-dependent energy storage may link ancient adaptation to famine and modern metabolic maladaptation associated with nutritional overabundance.


Asunto(s)
Enfermedades Metabólicas/genética , MicroARNs/genética , Adipocitos Marrones/patología , Adiposidad , Alelos , Animales , Diferenciación Celular , Línea Celular , Células Cultivadas , Dieta Alta en Grasa , Metabolismo Energético , Epigénesis Genética , Sitios Genéticos , Glucosa/metabolismo , Homeostasis , Humanos , Hipertrofia , Resistencia a la Insulina , Leptina/deficiencia , Leptina/metabolismo , Masculino , Mamíferos/genética , Ratones Endogámicos C57BL , Ratones Obesos , MicroARNs/metabolismo , Obesidad/genética , Oligonucleótidos/metabolismo , Especificidad de la Especie
9.
J Lipid Res ; 60(4): 856-868, 2019 04.
Artículo en Inglés | MEDLINE | ID: mdl-30782959

RESUMEN

Treatment with PPARγ agonists in vivo improves human adipocyte metabolism, but the cellular mechanisms and possible depot differences in responsiveness to their effects are poorly understood. To examine the ex vivo metabolic effects of rosiglitazone (Rosi), we cultured explants of human visceral (omental) and abdominal subcutaneous adipose tissues for 7 days. Rosi increased mRNA levels of transcriptional regulators of brite/beige adipocytes (PGC1α, PRDM16), triglyceride synthesis (GPAT3, DGAT1), and lipolysis (ATGL) similarly in adipose tissues from both depots. In parallel, Rosi increased key modulators of FA oxidation (UCP1, FABP3, PLIN5 protein), rates of FA oxidation, and protein levels of electron transport complexes, suggesting an enhanced respiratory capacity as confirmed in newly differentiated adipocytes. Rosi led to the formation of small lipid droplets (SLDs) around the adipocyte central lipid droplet; each SLD was decorated with redistributed mitochondria that colocalized with PLIN5. SLD maintenance required lipolysis and FA reesterification. Rosi thus coordinated a structural and metabolic remodeling in adipocytes from both visceral and subcutaneous depots that enhanced oxidative capacity. Selective targeting of these cellular mechanisms to improve adipocyte FA handling may provide a new approach to treat metabolic complications of obesity and diabetes.


Asunto(s)
Adipocitos/efectos de los fármacos , Tejido Adiposo/efectos de los fármacos , Hipoglucemiantes/farmacología , Gotas Lipídicas/efectos de los fármacos , Rosiglitazona/farmacología , Adipocitos/metabolismo , Tejido Adiposo/metabolismo , Adulto , Anciano , Femenino , Humanos , Gotas Lipídicas/metabolismo , Masculino , Persona de Mediana Edad , Oxidación-Reducción , Fenotipo
10.
Diabetes ; 68(3): 587-597, 2019 03.
Artículo en Inglés | MEDLINE | ID: mdl-30530781

RESUMEN

Visceral obesity is associated with insulin resistance and higher risk of type 2 diabetes and metabolic diseases. A limited ability of adipose tissues to remodel through the recruitment and differentiation of adipose stem cells (ASCs) is associated with adipose tissue inflammation and fibrosis and the metabolic syndrome. We show that the lower adipogenesis of omental (Om) compared with abdominal subcutaneous (Abdsc) ASCs was associated with greater secretion of TGFß ligands that acted in an autocrine/paracrine loop to activate SMAD2 and suppress adipogenesis. Inhibition of TGFß signaling rescued Om ASC differentiation. In Abdsc ASCs, low concentrations of dexamethasone suppressed TGFß signaling and enhanced adipogenesis, at least in part by increasing TGFBR3 protein that can sequester TGFß ligands. Om ASCs were resistant to these dexamethasone effects; recombinant TGFBR3 increased their differentiation. Pericellular fibrosis, a hallmark of dysfunctional adipose tissue, was greater in Om and correlated with higher level of tissue TGFß signaling activity and lower ASC differentiation. We conclude that glucocorticoids restrain cell-autonomous TGFß signaling in ASCs to facilitate adipogenesis and healthy remodeling in Abdsc and these processes are impaired in Om. Therapies directed at overcoming glucocorticoid resistance in visceral adipose tissue may improve remodeling and help prevent metabolic complications of visceral obesity.


Asunto(s)
Tejido Adiposo/metabolismo , Fibrosis/metabolismo , Glucocorticoides/farmacología , Epiplón/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Activinas/genética , Activinas/metabolismo , Adipogénesis/efectos de los fármacos , Adipogénesis/genética , Tejido Adiposo/citología , Adulto , Dexametasona/farmacología , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Femenino , Fibrosis/genética , Humanos , Interleucina-6/genética , Interleucina-6/metabolismo , Masculino , Persona de Mediana Edad , Epiplón/efectos de los fármacos , Proteoglicanos/genética , Proteoglicanos/metabolismo , Receptores de Factores de Crecimiento Transformadores beta/genética , Receptores de Factores de Crecimiento Transformadores beta/metabolismo , Células Madre/citología , Células Madre/efectos de los fármacos , Células Madre/metabolismo , Factor de Crecimiento Transformador beta/genética , Adulto Joven
11.
J Clin Endocrinol Metab ; 103(9): 3430-3438, 2018 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-29982704

RESUMEN

Context and Objective: Direct comparisons between types of dietary carbohydrate in terms of cardiometabolic risk indicators are limited. This study was designed to compare the effects of an isocaloric exchange of simple, refined, and unrefined carbohydrates on serum cardiometabolic risk indicators, adipose tissue inflammatory markers, and peripheral blood mononuclear cell (PBMC) fractional cholesterol efflux. Design, Participants, and Measures: Participants [postmenopausal women and men (N = 11), 65 ± 8 years, body mass index 29.8 ± 3.2 kg/m2, low-density lipoprotein (LDL) cholesterol ≥2.6 mmol/L] were provided with diets (60% energy from total carbohydrate, 15% from protein, 25% from fat) for 4.5 weeks in a randomized crossover design, with 2-week washout periods. The variable component was an isocaloric exchange of simple, refined, or unrefined carbohydrate-containing foods. Serum lipoprotein, glucose, insulin, and inflammatory marker concentrations were measured. Abdominal subcutaneous adipose tissue was aspirated to assess macrophage and inflammatory marker gene expression and ex vivo cytokine secretion, and PBMCs were isolated to assess ex vivo fractional cholesterol efflux. Results: Fasting serum LDL and non-high-density lipoprotein (HDL) cholesterol concentrations were higher after the refined compared with simple or unrefined carbohydrate-enriched diets (P < 0.01). Other serum measures, ex vivo fractional cholesterol efflux and adipose tissue gene expression and ex vivo cytokine secretion, were similar between diets. Conclusions: Diets enriched in refined compared with simple or unrefined carbohydrate resulted in higher fasting serum LDL and non-HDL cholesterol concentrations but had little effect on other cardiometabolic risk indicators. This small study raises the intriguing possibility that refined carbohydrate may have unique adverse effects on cardiometabolic risk indicators distinct from simple and unrefined carbohydrate.


Asunto(s)
Carbohidratos/química , Dieta/métodos , Carbohidratos de la Dieta/administración & dosificación , Mediadores de Inflamación/metabolismo , Grasa Subcutánea/metabolismo , Anciano , Biomarcadores/metabolismo , Glucemia/metabolismo , HDL-Colesterol/sangre , Estudios Cruzados , Citocinas/metabolismo , Ayuno/sangre , Femenino , Humanos , Insulina/sangre , Leucocitos Mononucleares , Lipoproteínas LDL/sangre , Masculino , Persona de Mediana Edad , Posmenopausia , Factores de Riesgo
12.
PLoS One ; 13(5): e0197777, 2018.
Artículo en Inglés | MEDLINE | ID: mdl-29799877

RESUMEN

White adipose tissue expands through both adipocyte hypertrophy and hyperplasia and it is hypothesized that fibrosis or excess accumulation of extracellular matrix within adipose tissue may limit tissue expansion contributing to metabolic dysfunction. The pathways that control adipose tissue remodeling are only partially understood, however it is likely that adipose tissue stromal and perivascular progenitors participate in fibrotic remodeling and also serve as adipocyte progenitors. The goal of this study was to investigate the role of the secreted extracellular matrix protein aortic carboxypeptidase-like protein (ACLP) on adipose progenitor differentiation in the context of adipose tissue fibrosis. Treatment of 10T1/2 mouse cells with recombinant ACLP suppressed adipogenesis and enhanced myofibroblast differentiation, which was dependent on transforming growth factor-ß receptor kinase activity. Mice fed a chronic high fat diet exhibited white adipose tissue fibrosis with elevated ACLP expression and cellular fractionation of these depots revealed that ACLP was co-expressed with collagens primarily in the inflammatory cell depleted stromal-vascular fraction (SVF). SVF cells isolated from mice fed a high fat diet secreted increased amounts of ACLP compared to low fat diet control SVF. These cells also exhibited reduced adipogenic differentiation capacity in vitro. Importantly, differentiation studies in primary human adipose stromal cells revealed that mature adipocytes do not express ACLP and exogenous ACLP administration blunted their differentiation potential while upregulating myofibroblastic markers. Collectively, these studies identify ACLP as a stromal derived mediator of adipose progenitor differentiation that may limit adipocyte expansion during white adipose tissue fibrosis.


Asunto(s)
Tejido Adiposo Blanco/patología , Tejido Adiposo/citología , Carboxipeptidasas/metabolismo , Miofibroblastos/citología , Proteínas Represoras/metabolismo , Regulación hacia Arriba , Tejido Adiposo/metabolismo , Tejido Adiposo Blanco/metabolismo , Animales , Diferenciación Celular , Células Cultivadas , Fibrosis , Humanos , Masculino , Ratones , Miofibroblastos/metabolismo , Receptores de Factores de Crecimiento Transformadores beta/metabolismo , Células del Estroma/citología , Células del Estroma/metabolismo
13.
J Leukoc Biol ; 103(4): 611-613, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29534319
14.
Arterioscler Thromb Vasc Biol ; 38(4): 733-743, 2018 04.
Artículo en Inglés | MEDLINE | ID: mdl-29348118

RESUMEN

OBJECTIVE: Adipose tissue cholesterol increases with adipocyte triglyceride content and size during development of obesity. However, how adipocyte cholesterol affects adipocyte function is poorly understood. The aim of this study was to evaluate the role of the cellular cholesterol exporter, Abca1 (ATP-binding cassette transporter A1), on adipose tissue function during diet-induced obesity. APPROACH AND RESULTS: Adiponectin Cre recombinase transgenic mice were crossed with Abca1flox/flox mice to generate ASKO (adipocyte-specific Abca1 knockout) mice. Control and ASKO mice were then fed a high-fat, high-cholesterol (45% calories as fat and 0.2% cholesterol) diet for 16 weeks. Compared with control mice, ASKO mice had a 2-fold increase in adipocyte plasma membrane cholesterol content and significantly lower body weight, epididymal fat pad weight, and adipocyte size. ASKO versus control adipose tissue had decreased PPARγ (peroxisome proliferator-activated receptor γ) and CCAAT/enhancer-binding protein expression, nuclear SREBP1 (sterol regulatory element-binding protein 1) protein, lipogenesis, and triglyceride accretion but similar Akt activation after acute insulin stimulation. Acute siRNA-mediated Abca1 silencing during 3T3L1 adipocyte differentiation reduced adipocyte Abca1 and PPARγ protein expression and triglyceride content. Systemic stimulated triglyceride lipolysis and glucose homeostasis were similar between control and ASKO mice. CONCLUSIONS: Adipocyte Abca1 is a key regulator of adipocyte lipogenesis and lipid accretion, likely because of increased adipose tissue membrane cholesterol, resulting in decreased activation of lipogenic transcription factors PPARγ and SREBP1.


Asunto(s)
Transportador 1 de Casete de Unión a ATP/deficiencia , Adipocitos/metabolismo , Tejido Adiposo/metabolismo , Colesterol en la Dieta , Dieta Alta en Grasa , Eliminación de Gen , Lipólisis , Obesidad/prevención & control , Células 3T3-L1 , Transportador 1 de Casete de Unión a ATP/genética , Adipocitos/patología , Adipogénesis , Tejido Adiposo/patología , Tejido Adiposo/fisiopatología , Animales , Colesterol en la Dieta/metabolismo , Modelos Animales de Enfermedad , Predisposición Genética a la Enfermedad , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Obesidad/genética , Obesidad/metabolismo , Obesidad/fisiopatología , PPAR gamma/metabolismo , Fenotipo , Proteína 1 de Unión a los Elementos Reguladores de Esteroles/metabolismo , Triglicéridos/metabolismo , Aumento de Peso
15.
Adv Exp Med Biol ; 1043: 29-51, 2017.
Artículo en Inglés | MEDLINE | ID: mdl-29224089

RESUMEN

Sex differences in adipose tissue distribution and the metabolic, endocrine, and immune functions of different anatomical fat depots have been described, but they are incompletely documented in the literature. It is becoming increasingly clear that adipose depots serve distinct functions in males and females and have specific physiological roles. However, the mechanisms that regulate the size and function of specific adipose tissues in men and women remain poorly understood. New insights from mouse models have advanced our understanding of depot differences in adipose growth and remodeling via the proliferation and differentiation of adipose progenitors that can expand adipocyte number in the tissue or simply replace dysfunctional older and larger adipocytes. A limited ability of a depot to expand or remodel can lead to excessive adipocyte hypertrophy, which is often correlated with metabolic dysfunction. However, the relationship of adipocyte size and function varies by depot and sex. For example, femoral adipose tissues of premenopausal women appear to have a greater capacity for adipose expansion via hyperplasia and hypertrophy; although larger, these gluteal-femoral adipocytes remain insulin sensitive. The microenvironment of specific depots, including the composition of the extracellular matrix and cellular composition, as well as cell-autonomous genetic differences, influences sex- and depot-dependent metabolic and growth properties. Although there are some species differences, studies of the molecular and physiological determinants of sex differences in adipocyte growth and function in humans and rodents are both needed for understanding sex differences in health and disease.


Asunto(s)
Adipocitos/metabolismo , Tejido Adiposo/metabolismo , Adiposidad , Adipocitos/patología , Adipogénesis , Tejido Adiposo/fisiopatología , Adiposidad/genética , Animales , Proliferación Celular , Microambiente Celular , Femenino , Disparidades en el Estado de Salud , Humanos , Masculino , Enfermedades Metabólicas/genética , Enfermedades Metabólicas/metabolismo , Enfermedades Metabólicas/patología , Enfermedades Metabólicas/fisiopatología , Modelos Animales , Obesidad/genética , Obesidad/metabolismo , Obesidad/patología , Obesidad/fisiopatología , Factores de Riesgo , Caracteres Sexuales , Factores Sexuales , Transducción de Señal
16.
Obesity (Silver Spring) ; 25(8): 1375-1383, 2017 08.
Artículo en Inglés | MEDLINE | ID: mdl-28649807

RESUMEN

OBJECTIVE: Lower body fat is associated with diminishing cardiometabolic risk. Physiological differences between gluteofemoral and abdominal subcutaneous adipocyte functions are known, but the molecular basis for depot differences in adipocyte function is poorly understood. The objective of this study was to identify depot differences in microRNA (miRNA) expression in human abdominal and gluteofemoral subcutaneous adipose tissues and their implication in gene regulation. METHODS: Abdominal and gluteofemoral adipose tissue aspirates obtained from 18 participants (9 male and 9 female, age 30 ± 1.5 y, BMI 27.3 ± 1.23 kg/m2 ) were analyzed for miRNA expression profiles by next-generation DNA sequencing. The raw reads were mapped to miRBase 17, and differentially expressed miRNAs were confirmed by qRT-PCR. The hsa-mimic-miR196a was transfected into cultured abdominal preadipocytes isolated from five women with obesity. Target gene expression was evaluated by RT-qPCR. RESULTS: Among the 640 miRNAs detected in adipose tissue, miR196a2, miR196a1, miR196b, and miR204 showed a higher expression in the gluteofemoral depot (fold change = 2.7, 2.3, 1.7, and 2.3, respectively) independent of sex. Bioinformatic analyses and human primary preadipocyte transfection with miR196 suggested that the differentially expressed miRNAs could directly or indirectly modulate homeobox (HOX) gene expression. CONCLUSIONS: The miR196 gene family could play an important role in the regulation of HOX gene expression in subcutaneous adipose tissue and in fat distribution variation.


Asunto(s)
Nalgas , Proteínas de Homeodominio/genética , MicroARNs/genética , Grasa Subcutánea/metabolismo , Adipocitos/metabolismo , Adulto , Índice de Masa Corporal , Biología Computacional , Femenino , Regulación de la Expresión Génica , Proteínas de Homeodominio/metabolismo , Humanos , Masculino , MicroARNs/metabolismo , Obesidad/genética , Obesidad/metabolismo , Análisis de Secuencia de ADN
17.
Growth Horm IGF Res ; 35: 17-20, 2017 08.
Artículo en Inglés | MEDLINE | ID: mdl-28628810

RESUMEN

OBJECTIVE: To investigate the effects of short-term GH administration on abdominal subcutaneous adipocyte size and CT attenuation in men with abdominal obesity. DESIGN: 6-week, randomized, double-blind, placebo-controlled study of GH (starting dose 2µg/kg/d) vs placebo of 15 abdominally obese men (mean age: 34±6years; mean BMI: 37.7±6.1kg/m2, mean IGF-1 SDS: -1.9±0.5) who underwent abdominal subcutaneous adipose tissue (SAT) aspirations to determine adipocyte size, CTs for body composition and measures of glucose tolerance at baseline and 6weeks. GH dosing was titrated to target IGF-1 levels in the upper normal age-appropriate range. RESULTS: GH administration decreased subcutaneous abdominal adipocyte size compared to placebo. Adipocyte size was positively associated with 120-min glucose and HOMA-IR and inversely associated with peak-stimulated GH and CT attenuation. CT attenuation of SAT was inversely associated with 120-min glucose and HOMA-IR and increased following GH administration. CONCLUSION: In men with abdominal obesity, subcutaneous abdominal adipocyte size is positively associated with measures of impaired glucose tolerance and administration of GH at doses that raise IGF-1 levels within the normal range, decreases abdominal subcutaneous adipocyte size, suggesting that GH administration improves the health of adipose tissue. Clinical trials number: NCT00131378.


Asunto(s)
Adipocitos/efectos de los fármacos , Adipocitos/patología , Hormona de Crecimiento Humana/uso terapéutico , Obesidad Abdominal/tratamiento farmacológico , Grasa Subcutánea Abdominal/efectos de los fármacos , Grasa Subcutánea Abdominal/patología , Adulto , Composición Corporal/efectos de los fármacos , Tamaño de la Célula/efectos de los fármacos , Método Doble Ciego , Humanos , Masculino , Obesidad Abdominal/patología , Placebos
18.
Mol Metab ; 6(1): 125-137, 2017 01.
Artículo en Inglés | MEDLINE | ID: mdl-28123943

RESUMEN

OBJECTIVE: Insulin signaling plays a unique role in the regulation of energy homeostasis and the impairment of insulin action is associated with altered lipid metabolism, obesity, and Type 2 Diabetes. The main aim of this study was to provide further insight into the regulatory mechanisms governing the insulin signaling pathway by investigating the role of non-proteolytic ubiquitination in insulin-mediated activation of AKT. METHODS: The molecular mechanism of AKT regulation through ubiquitination is first dissected in vitro in 3T3-L1 preadipocytes and then validated in vivo using mice with adipo-specific deletion of GPS2, an endogenous inhibitor of Ubc13 activity (GPS2-AKO mice). RESULTS: Our results indicate that K63 ubiquitination is a critical component of AKT activation in the insulin signaling pathway and that counter-regulation of this step is provided by GPS2 preventing AKT ubiquitination through inhibition of Ubc13 enzymatic activity. Removal of this negative checkpoint, through GPS2 downregulation or genetic deletion, results in sustained activation of insulin signaling both in vitro and in vivo. As a result, the balance between lipid accumulation and utilization is shifted toward storage in the adipose tissue and GPS2-AKO mice become obese under normal laboratory chow diet. However, the adipose tissue of GPS2-AKO mice is not inflamed, the levels of circulating adiponectin are elevated, and systemic insulin sensitivity is overall improved. CONCLUSIONS: Our findings characterize a novel layer of regulation of the insulin signaling pathway based on non-proteolytic ubiquitination of AKT and define GPS2 as a previously unrecognized component of the insulin signaling cascade. In accordance with this role, we have shown that GPS2 presence in adipocytes modulates systemic metabolism by restricting the activation of insulin signaling during the fasted state, whereas in absence of GPS2, the adipose tissue is more efficient at lipid storage, and obesity becomes uncoupled from inflammation and insulin resistance.


Asunto(s)
Tejido Adiposo/metabolismo , Insulina/metabolismo , Péptidos y Proteínas de Señalización Intracelular/fisiología , Células 3T3 , Adipocitos/metabolismo , Animales , Diabetes Mellitus Tipo 2/metabolismo , Inflamación/genética , Insulina/genética , Insulina/fisiología , Resistencia a la Insulina/genética , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Ratones , Obesidad/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal , Enzimas Ubiquitina-Conjugadoras/antagonistas & inhibidores , Enzimas Ubiquitina-Conjugadoras/metabolismo , Ubiquitinación
19.
J Obes Metab Syndr ; 26(3): 172-180, 2017 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-31089514

RESUMEN

Men and women are different in their fat mass and distribution pattern. The gynoid-type fat distribution, accumulation in lower-body, is considered to be protective while the android-type accumulation in upper-body, both in abdominal subcutaneous and visceral depots, is detrimental. Sex-dependent depot differences in adipose metabolic and endocrine functions are thought to contribute to the sexual disparity in fat distribution as well as its association with cardiometabolic risks. Although molecular details have not been completely elucidated, available evidence shows that sex steroid hormones are important factors governing sexual dimorphism in adipose tissue distribution and hence, risks for metabolic diseases. We will review sex-dependent heterogeneities in adipose tissue properties that can link their depot-specific biology to metabolic complications in men and women. In addition, we will also review how sex steroids regulate adipose tissue biology, both development and functional characteristics, with emphasis on their depot-dependent actions.

20.
Obesity (Silver Spring) ; 25(1): 15, 2017 01.
Artículo en Inglés | MEDLINE | ID: mdl-27935267
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