RESUMEN
Brown adipocytes are found in several fat depots, however, the origins and contributions of different lineages of adipogenic progenitor cells (APCs) to these depots are unclear. In this issue of Developmental Cell, Shi et al. show that platelet-derived growth factor receptor ß (PDGFRß)-lineage and T-box transcription factor 18 (TBX18)-lineage APCs differentially contribute to brown adipogenesis across these depots.
Asunto(s)
Adipogénesis , Receptores Notch , Células Madre , Adipogénesis/fisiología , Animales , Receptores Notch/metabolismo , Células Madre/metabolismo , Células Madre/citología , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Pardo/citología , Humanos , Adipocitos Marrones/metabolismo , Adipocitos Marrones/citología , Receptor beta de Factor de Crecimiento Derivado de Plaquetas/metabolismo , Receptor beta de Factor de Crecimiento Derivado de Plaquetas/genética , Diferenciación Celular , Linaje de la Célula , Ratones , Transducción de SeñalRESUMEN
De novo brown adipogenesis holds potential in combating the epidemics of obesity and diabetes. However, the identity of brown adipocyte progenitor cells (APCs) and their regulation have not been extensively explored. Here, through in vivo lineage tracing and mouse modeling, we observed that platelet-derived growth factor receptor beta (PDGFRß)+ pericytes give rise to developmental brown adipocytes but not to those in adult homeostasis. By contrast, T-box 18 (TBX18)+ pericytes contribute to brown adipogenesis throughout both developmental and adult stages, though in a depot-specific manner. Mechanistically, Notch inhibition in PDGFRß+ pericytes promotes brown adipogenesis by downregulating PDGFRß. Furthermore, inhibition of Notch signaling in PDGFRß+ pericytes mitigates high-fat, high-sucrose (HFHS)-induced glucose and metabolic impairment in mice during their development and juvenile phases. Collectively, these findings show that the Notch/PDGFRß axis negatively regulates developmental brown adipogenesis, and its repression promotes brown adipose tissue expansion and improves metabolic health.
Asunto(s)
Adipocitos Marrones , Adipogénesis , Diferenciación Celular , Receptor beta de Factor de Crecimiento Derivado de Plaquetas , Receptores Notch , Células Madre , Animales , Receptor beta de Factor de Crecimiento Derivado de Plaquetas/metabolismo , Receptor beta de Factor de Crecimiento Derivado de Plaquetas/genética , Receptores Notch/metabolismo , Ratones , Adipocitos Marrones/metabolismo , Adipocitos Marrones/citología , Células Madre/metabolismo , Células Madre/citología , Transducción de Señal , Pericitos/metabolismo , Pericitos/citología , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Pardo/citología , Ratones Endogámicos C57BL , MasculinoRESUMEN
Promoting the thermogenic function of brown adipose tissue (BAT) is a promising strategy to combat obesity and metabolic disorders. While much is known about the transcriptional regulation of BAT activation, however, the underlying mechanism of post-transcriptional control by RNA binding proteins remains largely unknown. Here, we found that RNA binding protein Y-box binding protein 1 (YBX1) expression was abundant in BAT and induced by cold exposure and a ß-adrenergic agonist in mice. Loss-of-function experiments showed that YBX1 deficiency inhibited mouse primary brown adipocyte differentiation and thermogenic function. Further study showed that YBX1 positively regulates thermogenesis through enhancing mitophagy. Mechanistically, RNA immunoprecipitation identified that YBX1 directly targeted the transcripts of PTEN-induced kinase 1 (Pink1) and parkin RBR E3 ubiquitin-protein ligase (Prkn), two key regulators of mitophagy. RNA decay assay proved that loss of YBX1 decreased mRNA stability of Pink1 and Prkn, leading to reduced protein expression, thereby alleviating mitophagy and inhibiting thermogenic program. Importantly, in vivo experiments demonstrated that YBX1 overexpression in BAT promoted thermogenesis and mitophagy in mice. Collectively, our results reveal novel insight into the molecular mechanism of YBX1 in post-transcriptional regulation of PINK1/PRKN-mediated mitophagy and highlight the critical role of YBX1 in brown adipogenesis and thermogenesis.
Asunto(s)
Adipogénesis , Mitofagia , Termogénesis , Factores de Transcripción/metabolismo , Adipocitos Marrones/citología , Adipocitos Marrones/metabolismo , Animales , Células Cultivadas , Ratones , Ratones Endogámicos C57BL , Proteínas Quinasas/metabolismo , Factores de Transcripción/genética , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
The development of hepatic insulin resistance (IR) is a critical factor in developing type 2 diabetes (T2D), where insulin fails to inhibit hepatic glucose production but retains its capacity to promote hepatic de novo lipogenesis leading to hyperglycemia and hypertriglyceridemia. Improving insulin sensitivity can be effective in preventing and treating T2D. However, selective control of glucose and lipid synthesis has been difficult. It is known that excess white adipose tissue is detrimental to insulin sensitivity, whereas brown adipose tissue transplantation can restore it in diabetic mice. However, challenges remain in our understanding of liver-adipose communication because the confounding effects of hypothalamic regulation of metabolic function cannot be ruled out in previous studies. There is a lack ofin vitromodels that use primary cells to study cellular-crosstalk under insulin resistant conditions. Building upon our previous work on the microfluidic primary liver and adipose organ-on-chips, we report for the first time, the development of an integrated insulin resistant liver-adipose (white and brown) organ-on-chip. The design of the microfluidic device was carried out using computational fluid dynamics; the experimental studies were conducted by carrying out detailed biochemical analysis RNA-seq analysis on both cell types. Further, we tested the hypothesis that brown adipocytes (BAC) regulated both hepatic insulin sensitivity and de novo lipogenesis. Our results show that BAC effectively restored insulin sensitivity and supressed hepatic glucose production and de novo lipogenesis suggesting that the experimental platform could be useful for identifying potential therapeutics to treat IR and diabetes.
Asunto(s)
Adipocitos Marrones , Adipocitos Blancos , Resistencia a la Insulina/fisiología , Hígado/metabolismo , Análisis de Matrices Tisulares , Adipocitos Marrones/citología , Adipocitos Marrones/metabolismo , Adipocitos Blancos/citología , Adipocitos Blancos/metabolismo , Animales , Diabetes Mellitus Tipo 2/metabolismo , Glucosa/metabolismo , Dispositivos Laboratorio en un Chip , Lipogénesis/fisiología , Masculino , Ratones , Ratones Endogámicos C57BL , Técnicas Analíticas Microfluídicas/instrumentación , Técnicas Analíticas Microfluídicas/métodos , Análisis de Matrices Tisulares/instrumentación , Análisis de Matrices Tisulares/métodosRESUMEN
AIMS: Prednisone is a corticosteroid-derived drug which is widely used for its role in immunosuppression and treatment of lung disorders. The current study reports, for the first time, the critical role of prednisone in the induction of white fat browning, thereby promoting thermogenic effect in cultured white adipocytes. MAIN METHODS: The fat-browning activity of prednisone was evaluated in 3T3-L1 cells by quantitative real-time PCR, immunoblot analysis, immunofluorescence, and molecular docking techniques. KEY FINDINGS: Exposure to prednisone stimulated browning in 3T3-L1 white adipocytes by increasing the expressions of core fat browning marker proteins (UCP1, PGC-1α and PRDM16) as well as beige-specific genes (Cd137, Cidea, Cited1, and Tbx1) via ATF2 and CREB activation mediated by p38 MAPK and ERK signaling, respectively. Prednisone exposure also resulted in the robust activation of lipolytic and fatty acid oxidation marker proteins, thereby increasing mitochondrial biogenesis. In addition, prednisone treatment resulted in reduced expression levels of adipogenic transcription factors while elevating SIRT1, as well as attenuation of lipogenesis and lipid droplets formation. Furthermore, molecular docking and mechanistic studies demonstrated the recruitment of beige fat by prednisone via the ß3-AR/p38 MAPK/ERK signaling pathway. SIGNIFICANCE: Taken together, these results indicate the unique role of prednisone as a fat-browning stimulant, and demonstrate its therapeutic potential in the treatment of obesity by enhancing thermogenesis.
Asunto(s)
Adipocitos Marrones/citología , Adipocitos Blancos/citología , Proteína Quinasa 1 Activada por Mitógenos/metabolismo , Proteína Quinasa 3 Activada por Mitógenos/metabolismo , Prednisona/farmacología , Receptores Adrenérgicos beta 3/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo , Adipocitos Marrones/efectos de los fármacos , Adipocitos Marrones/metabolismo , Adipocitos Blancos/efectos de los fármacos , Adipocitos Blancos/metabolismo , Animales , Antiinflamatorios/farmacología , Regulación de la Expresión Génica , Ratones , Proteína Quinasa 1 Activada por Mitógenos/genética , Proteína Quinasa 3 Activada por Mitógenos/genética , Receptores Adrenérgicos beta 3/genética , Proteínas Quinasas p38 Activadas por Mitógenos/genéticaRESUMEN
Maternal obesity (MO) predisposes offspring to obesity and metabolic disorders but little is known about the contribution of offspring brown adipose tissue (BAT). We find that MO impairs fetal BAT development, which persistently suppresses BAT thermogenesis and primes female offspring to metabolic dysfunction. In fetal BAT, MO enhances expression of Dio3, which encodes deiodinase 3 (D3) to catabolize triiodothyronine (T3), while a maternally imprinted long noncoding RNA, Dio3 antisense RNA (Dio3os), is inhibited, leading to intracellular T3 deficiency and suppression of BAT development. Gain and loss of function shows Dio3os reduces D3 content and enhances BAT thermogenesis, rendering female offspring resistant to high fat diet-induced obesity. Attributing to Dio3os inactivation, its promoter has higher DNA methylation in obese dam oocytes which persists in fetal and adult BAT, uncovering an oocyte origin of intergenerational obesity. Overall, our data uncover key features of Dio3os activation in BAT to prevent intergenerational obesity and metabolic dysfunctions.
Asunto(s)
Tejido Adiposo Pardo/metabolismo , Obesidad/genética , ARN Largo no Codificante/genética , Adipocitos Marrones/citología , Adipocitos Marrones/metabolismo , Adipogénesis , Tejido Adiposo Pardo/citología , Animales , Diferenciación Celular , Metilación de ADN , Proteínas de Unión al ADN/metabolismo , Dieta Occidental/efectos adversos , Metabolismo Energético , Femenino , Impresión Genómica , Yoduro Peroxidasa/metabolismo , Ratones , Obesidad/etiología , Obesidad/metabolismo , Obesidad Materna/genética , Obesidad Materna/metabolismo , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/metabolismo , Embarazo , ARN Largo no Codificante/metabolismo , Termogénesis , Factores de Transcripción/metabolismo , Triyodotironina/metabolismoRESUMEN
Recently, it has been irrefutably discovered that brown adipocytes dissipate energy as heat and protect against obesity. Researchers make great efforts to explore approaches for its activation. Lipoxin A4 (LXA4) has been proven to reverse adipose tissue inflammation and improve insulin resistance, but its function on brown adipocyte differentiation has been poorly understood, which therefore to be investigated in the present study. Mouse embryonic fibroblasts (MEFs) were induced and differentiated to model brown adipocytes, and treated with LXA4 at 0, 1, 5, and 10 nM for 0-14 d. Afterwards, Oil Red O staining detected lipid droplets. In differentiated MEFs with or without LXA4 (10 nM) treatment, western blot and quantitative real-time polymerase chain reaction (qRT-PCR) assessed adipocyte browning marker uncoupling protein 1 (UCP-1), and brown adipogenesis markers peroxisome proliferator-activated receptor gamma (PPARγ), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), cyclooxygenase-2 (COX-2), and positive regulation domain containing 16 (PRDM16) as well as lipogenic genes of stearoyl-CoA desaturase 1 (SCD1), fatty acid synthase (FASN), glucose transporter type 4 (GLUT4), and carbohydrate response element binding protein (ChREBP). The induced differentiation of MEFs toward brown adipocytes was successful. LXA4 promoted intracellular accumulation of lipid droplets of induced cells and increased UCP-1 expression in a dose- or time-dependent manner. Under the administration of LXA4, brown adipogenesis markers and lipogenic genes were further upregulated. LXA4 made a contribution to induce differentiation of MEFs to brown adipocytes, which could be regarded a new drug target for obesity management.
Asunto(s)
Adipogénesis/efectos de los fármacos , Fibroblastos/efectos de los fármacos , Lipoxinas/farmacología , Adipocitos Marrones/citología , Adipocitos Marrones/efectos de los fármacos , Adipogénesis/fisiología , Animales , Diferenciación Celular/efectos de los fármacos , Diferenciación Celular/fisiología , Células Cultivadas , Relación Dosis-Respuesta a Droga , Fibroblastos/citología , Fibroblastos/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Gotas Lipídicas/efectos de los fármacos , Gotas Lipídicas/metabolismo , Lipoxinas/administración & dosificación , Ratones , Proteína Desacopladora 1/genética , Proteína Desacopladora 1/metabolismoRESUMEN
We visualized a dynamic process of fatty acid uptake of brown adipocytes using a time-lapse ultra-broadband multiplex coherent anti-Stokes Raman scattering (CARS) spectroscopic imaging system with an onstage incubator. Combined with the deuterium labeling technique, the intracellular uptake of saturated fatty acids was traced up to 9 h, a substantial advance over the initial multiplex CARS system, with an analysis time of 80 min. Characteristic metabolic activities of brown adipocytes, such as resistance to lipid saturation, were elucidated, supporting the utility of the newly developed system.
Asunto(s)
Adipocitos Marrones/citología , Adipocitos Marrones/metabolismo , Ácidos Grasos/metabolismo , Incubadoras , Metabolismo de los Lípidos , Espectrometría Raman , Animales , Línea Celular , Ratones , Imagen de Lapso de TiempoRESUMEN
We studied the effect of bacterial pathogen-associated molecular patterns and myokines on the secretion of adipokines by mesenchymal stem cells (MSC) and products of their adipogenic differentiation. The secretion of adiponectin, adipsin, leptin, and insulin by adipogenically differentiated cell cultures was quantitatively determined using multiplex ELISA. MSC obtained from the stromal vascular fraction of human subcutaneous adipose tissue were shown to secrete a known adipokine adipsin. The ability of white adipocytes to secrete significant amounts of insulin (in vitro) has been shown for the first time. Control cultures of white adipocytes secreted much higher levels of adiponectin, leptin, and insulin when compared to other adipocytes cultures. On the other hand, beige and brown adipocyte cultures secreted more adipsin than white adipocyte cultures. The influence of myokine ß-aminoisobutyric acid on the secretion of adipsin in MSC, white, beige, and brown adipocytes was also studied.
Asunto(s)
Adipocitos Beige/efectos de los fármacos , Adipocitos Marrones/efectos de los fármacos , Adipocitos Blancos/efectos de los fármacos , Adipoquinas/farmacología , Ácidos Aminoisobutíricos/farmacología , Flagelina/farmacología , Lipopolisacáridos/farmacología , Adipocitos Beige/citología , Adipocitos Beige/metabolismo , Adipocitos Marrones/citología , Adipocitos Marrones/metabolismo , Adipocitos Blancos/citología , Adipocitos Blancos/metabolismo , Adipogénesis/efectos de los fármacos , Adipogénesis/genética , Adiponectina/genética , Adiponectina/metabolismo , Tejido Adiposo Pardo/citología , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Pardo/cirugía , Diferenciación Celular/efectos de los fármacos , Factor D del Complemento/genética , Factor D del Complemento/metabolismo , Regulación de la Expresión Génica , Humanos , Insulina/genética , Insulina/metabolismo , Leptina/genética , Leptina/metabolismo , Lipectomía/métodos , Células Madre Mesenquimatosas/citología , Células Madre Mesenquimatosas/efectos de los fármacos , Células Madre Mesenquimatosas/metabolismo , Especificidad de Órganos , Cultivo Primario de CélulasRESUMEN
Obesity and metabolic disorders caused by energy surplus pose an increasing concern within the global population. Brown adipose tissue (BAT) dissipates energy through mitochondrial non-shivering thermogenesis, thus representing a powerful agent against obesity. Here we explore the novel role of a mitochondrial outer membrane protein, LETM1-domain containing 1 (LETMD1), in BAT. We generated a knockout (Letmd1KO ) mouse model and analyzed BAT morphology, function and gene expression under various physiological conditions. While the Letmd1KO mice are born normally and have normal morphology and body weight, they lose multilocular brown adipocytes completely and have diminished mitochondrial abundance, DNA copy number, cristae structure, and thermogenic gene expression in the intrascapular BAT, associated with elevated reactive oxidative stress. In consequence, the Letmd1KO mice fail to maintain body temperature in response to acute cold exposure without food and become hypothermic within 4 h. Although the cold-exposed Letmd1KO mice can maintain body temperature in the presence of food, they cannot upregulate expression of uncoupling protein 1 (UCP1) and convert white to beige adipocytes, nor can they respond to adrenergic stimulation. These results demonstrate that LETMD1 is essential for mitochondrial structure and function, and thermogenesis of brown adipocytes.
Asunto(s)
Adipocitos Marrones/metabolismo , Tejido Adiposo Pardo/metabolismo , Mitocondrias/metabolismo , Proteínas Oncogénicas/fisiología , Receptores de Superficie Celular/fisiología , Termogénesis , Adipocitos Marrones/citología , Tejido Adiposo Pardo/citología , Animales , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Obesidad/metabolismoRESUMEN
Despite peroxisomes being important partners of mitochondria by carrying out fatty acid oxidation in brown adipocytes, no clear evidence concerning peroxisome origin and way(s) of biogenesis exists. Herein we used methimazole-induced hypothyroidism for 7, 15, and 21 days to study peroxisomal remodeling and origin in rat brown adipocytes. We found that peroxisomes originated via both canonic, and de novo pathways. Each pathway operates in euthyroid control and over the course of hypothyroidism, in a time-dependent manner. Hypothyroidism increased the peroxisomal number by 1.8-, 3.6- and 5.8-fold on days 7, 15, and 21. Peroxisomal presence, their distribution, and their degree of maturation were heterogeneous in brown adipocytes in a Harlequin-like manner, reflecting differences in their origin. The canonic pathway, through numerous dumbbell-like and "pearls on strings" structures, supported by high levels of Pex11ß and Drp1, prevailed on day 7. The de novo pathway of peroxisomal biogenesis started on day 15 and became dominant by day 21. The transition of peroxisomal biogenesis from canonic to the de novo pathway was driven by increased levels of Pex19, PMP70, Pex5S, and Pex26 and characterized by numerous tubular structures. Furthermore, specific peroxisomal origin from mitochondria, regardless of thyroid status, indicates their mutual regulation in rat brown adipocytes.
Asunto(s)
Adipocitos Marrones/citología , Hipotiroidismo/fisiopatología , Peroxisomas/fisiología , Adipocitos Marrones/fisiología , Animales , Mitocondrias/metabolismo , Oxidación-Reducción , PPAR alfa/metabolismo , PPAR gamma/metabolismo , Ratas , Ratas Wistar , Factores de TiempoRESUMEN
3-hydroxymorphinan (3-HM), a metabolite of dextromethorphan, has previously been reported to have anti-inflammatory, anti-oxidative stress, and neuroprotective effects. However, its effect on energy metabolism in adipocytes remains unclear. Herein, we investigated 3-hydroxymorphinan (3-HM) effects on mitochondrial biogenesis, oxidative stress, and lipid accumulation in 3T3-L1 adipocytes. Further, we explored 3-HM-associated molecular mechanisms. Mouse adipocyte 3T3-L1 cells were treated with 3-HM, and various protein expression levels were determined by western blotting analysis. Mitochondria accumulation and lipid accumulation were measured by staining methods. Cell toxicity was assessed by cell viability assay. We found that treatment of 3T3-L1 adipocytes with 3-HM increased expression of brown adipocyte markers, such as uncoupling protein-1 (UCP-1) and peroxisome proliferator-activated receptor-gamma coactivator 1-alpha (PGC-1α). 3-HM promotes mitochondrial biogenesis and its-mediated gene expression. Additionally, 3-HM treatment suppressed mitochondrial ROS generation and superoxide along with improved mitochondrial complex I activity. We found that treatment of 3-HM enhanced AMPK phosphorylation. siRNA-mediated suppression of AMPK reversed all these changes in 3T3-L1 adipocytes. In sum, 3-HM promotes mitochondrial biogenesis and browning and attenuates oxidative stress and lipid accumulation in 3T3-L1 adipocytes via AMPK signaling. Thus, 3-HM-mediated AMPK activation can be considered a therapeutic approach for treating obesity and related diseases.
Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Adipocitos Marrones/efectos de los fármacos , Adipocitos/efectos de los fármacos , Dextrometorfano/análogos & derivados , Biogénesis de Organelos , Transducción de Señal/efectos de los fármacos , Células 3T3-L1 , Proteínas Quinasas Activadas por AMP/genética , Adipocitos/citología , Adipocitos/metabolismo , Adipocitos Marrones/citología , Adipocitos Marrones/metabolismo , Animales , Western Blotting , Supervivencia Celular/efectos de los fármacos , Dextrometorfano/farmacología , Metabolismo de los Lípidos/efectos de los fármacos , Lipogénesis/efectos de los fármacos , Ratones , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Estrés Oxidativo/efectos de los fármacos , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/metabolismo , Fosforilación/efectos de los fármacos , Interferencia de ARN , Proteína Desacopladora 1/metabolismoRESUMEN
Brown adipocytes (BA) are a specialized fat cell which possesses a high capacity for fuel oxidation combined with heat production. The maintenance of high metabolic activity in BA requires elevated oxidation of fuel through the tricarboxylic acid cycle. Pyruvate carboxylase (PC) was previously proposed to be essential for coordination between fuel oxidation and thermogenesis. By differentiating human pluripotent stem cells to mature BA in vitro, we showed that ablation of PC gene by CRISPR Cas9 genome engineering did not impair the ability of stem cells to generate mature BA. However, brown adipocytes deficient for PC expression displayed a 35% reduction in ATP-linked respiration, but not thermogenesis under both basal and isoproterenol-stimulated conditions. This relatively mild impairment of ATP-link respiration in PC knockout BA was protected by increased spare mitochondrial respiratory capacity. Taken together, this study highlights the role of PC in supporting fuel oxidation rather than thermogenesis in human BA.
Asunto(s)
Adenosina Trifosfato/metabolismo , Adipocitos Marrones/metabolismo , Diferenciación Celular/fisiología , Consumo de Oxígeno/fisiología , Células Madre Pluripotentes/metabolismo , Piruvato Carboxilasa/metabolismo , Adipocitos Marrones/citología , Adipocitos Marrones/efectos de los fármacos , Western Blotting , Broncodilatadores/farmacología , Diferenciación Celular/genética , Células Cultivadas , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Expresión Génica , Técnicas de Inactivación de Genes , Humanos , Isoproterenol/farmacología , Oxidación-Reducción/efectos de los fármacos , Consumo de Oxígeno/genética , Células Madre Pluripotentes/citología , Piruvato Carboxilasa/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Termogénesis/efectos de los fármacos , Termogénesis/genética , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Proteína Desacopladora 1/genética , Proteína Desacopladora 1/metabolismoRESUMEN
Brown adipose tissue (BAT) is specialized for uncoupled heat production through mitochondrion fueled majorly from fatty acids (FAs) of lipid droplets (LDs). How the interaction between the two organelles contributes the generation of heat remains elusive. Here, we report that LD-anchored mitochondria (LDAM) were observed in the BAT of mice raised at three different temperatures, 30 °C, 23 °C, and 6 °C. The biochemical analyses including Western blotting of electron transport chain subunits showed that LDAM were functional. Comparative proteomics analysis was conducted, which revealed differential expressions of proteins between LDAM and cytoplasmic mitochondria (CM) at different temperatures. Higher expressions of proteins at low temperature were observed for i) FA ß-oxidation in LDAM including FA synthesis and uncoupling, ii) pseudo-futile cycle in CM, and iii) two shuttle systems: glycerol 3-phosphate in both CM and LDAM and citrate malate in CM. Together, these results suggest that LDs and LDAM form a preorganized and functional organelle complex that permits the rapid response to cold.
Asunto(s)
Adipocitos Marrones/metabolismo , Frío/efectos adversos , Metabolismo Energético/genética , Gotas Lipídicas/metabolismo , Mitocondrias/metabolismo , Adipocitos Marrones/citología , Adipocitos Marrones/ultraestructura , Tejido Adiposo Pardo/citología , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Pardo/ultraestructura , Animales , Antígenos CD36/metabolismo , Fraccionamiento Celular , Separación Celular , Ácidos Grasos/metabolismo , Regulación de la Expresión Génica , Gotas Lipídicas/ultraestructura , Metabolismo de los Lípidos/genética , Masculino , Ratones , Microscopía Electrónica de Transmisión , Mitocondrias/ultraestructura , Oxidación-Reducción , Proteómica , Proteínas de Transporte Vesicular/metabolismoRESUMEN
Changes to mitochondrial architecture are associated with various adaptive and pathogenic processes. However, quantification of changes to mitochondrial structures is limited by the yet unmet challenge of defining the borders of each individual mitochondrion within an image. Here, we describe a novel method for segmenting primary brown adipocyte (BA) mitochondria images. We describe a granular approach to quantifying subcellular structures, particularly mitochondria in close proximity to lipid droplets: peridroplet mitochondria. In addition, we lay out a novel machine-learning-based mitochondrial segmentation method that eliminates the bias of manual mitochondrial segmentation and improves object recognition compared to conventional thresholding analyses. By applying these methods, we discovered a significant difference between cytosolic and peridroplet BA mitochondrial H2O2 production and validated the machine-learning algorithm in BA via norepinephrine-induced mitochondrial fragmentation and comparing manual analyses to the automated analysis. This approach provides a high-throughput analysis protocol to quantify ratiometric probes in subpopulations of mitochondria in adipocytes.
Asunto(s)
Adipocitos Marrones/metabolismo , Ensayos Analíticos de Alto Rendimiento/métodos , Procesamiento de Imagen Asistido por Computador/métodos , Gotas Lipídicas/metabolismo , Aprendizaje Automático , Mitocondrias/metabolismo , Imagen Óptica/métodos , Adipocitos Marrones/citología , Algoritmos , Humanos , Gotas Lipídicas/química , Mitocondrias/ultraestructuraRESUMEN
Brown adipose tissue (BAT) is well known to burn calories through uncoupled respiration, producing heat to maintain body temperature. This 'calorie wasting' feature makes BAT a special tissue, which can function as an 'energy sink' in mammals. While a combination of high energy intake and low energy expenditure is the leading cause of overweight and obesity in modern society, activating a safe 'energy sink' has been proposed as a promising obesity treatment strategy. Metabolically, lipids and glucose have been viewed as the major energy substrates in BAT, while succinate, lactate, branched-chain amino acids, and other metabolites can also serve as energy substrates for thermogenesis. Since the cataplerotic and anaplerotic reactions of these metabolites interconnect with each other, BAT relies on its dynamic, flexible, and complex metabolism to support its special function. In this review, we summarize how BAT orchestrates the metabolic utilization of various nutrients to support thermogenesis and contributes to whole-body metabolic homeostasis.
Asunto(s)
Adipocitos Marrones/metabolismo , Tejido Adiposo Pardo/metabolismo , Metabolismo Energético/genética , Metabolismo de los Lípidos/genética , Obesidad/genética , Termogénesis/genética , Adipocitos Marrones/citología , Tejido Adiposo Pardo/citología , Aminoácidos de Cadena Ramificada/metabolismo , Animales , Fluorodesoxiglucosa F18/administración & dosificación , Glucosa/metabolismo , Homeostasis/genética , Humanos , Ácido Láctico/metabolismo , Obesidad/diagnóstico por imagen , Obesidad/metabolismo , Obesidad/patología , Tomografía de Emisión de Positrones , Ácido Succínico/metabolismoRESUMEN
AIMS: Browning induction (beiging) of white adipocytes is an emerging prospective strategy to defeat obesity and its related metabolic disorders. Cytochrome P450 2E1 (CYP2E1), a membrane protein which belongs to the cytochrome P450 superfamily, reportedly functions in the xenobiotic metabolism in the body, especially ethanol metabolism. Although previous studies have reported the effect of CYP2E1 on obesity in animal models, the data remains controversial. In the current study, we investigate for the first time, the role of CYP2E1 in lipid metabolism in 3T3-L1 white adipocytes, with a focus on fat browning. METHODS: 3T3-L1 white adipocytes and Cyp2e1 siRNA were applied to investigate the role of CYP2E1 in white adipocytes. After that, cells were seperately exposed to ß3-AR agonist, ß3-AR antagonist and p38 inhibitor to identify the pathway which CYP2E1 was involved in to regulate browning event in white adipocytes. KEY FINDINGS: We found that CYP2E1 deficiency results in reduced adipogenesis and lipogenesis as well as brown adipocyte-like phenotype induction. A mechanistic study to identify the molecular signals for CYP2E1 regulation in the browning of white adipocytes revealed that CYP2E1 inhibition deters the ß3-adrenergic receptor activation and its downstream targets. SIGNIFICANCE: Our data unveilved a previously unknown mechanism in the regulation of browning by CYP2E1 in 3T3-L1 white adipocytes, suggesting that CYP2E1 is a promising molecular target for the treatment of obesity and its related diseases.
Asunto(s)
Adipocitos Marrones/metabolismo , Adipocitos Blancos/metabolismo , Citocromo P-450 CYP2E1/metabolismo , Lipólisis , Células 3T3-L1 , Adipocitos Marrones/citología , Adipocitos Blancos/citología , Adipogénesis , Animales , Citocromo P-450 CYP2E1/genética , Silenciador del Gen , Metabolismo de los Lípidos , RatonesRESUMEN
Excessive fat accumulation in the body causes overweight and obesity. To date, research has confirmed that there are two types of adipose tissue with opposing functions: lipid-storing white adipose tissue (WAT) and lipid-burning brown adipose tissue (BAT). After the rediscovery of the presence of metabolically active BAT in adults, BAT has received increasing attention especially since activation of BAT is considered a promising way to combat obesity and associated comorbidities. It has become clear that energy homeostasis differs between the sexes, which has a significant impact on the development of pathological conditions such as type 2 diabetes. Sex differences in BAT activity may contribute to this and, therefore, it is important to address the underlying mechanisms that contribute to sex differences in BAT activity. In this review, we discuss the role of sex hormones in the regulation of BAT activity under physiological and some pathological conditions. Given the increasing number of studies suggesting a crosstalk between sex hormones and the hypothalamic-pituitary-adrenal axis in metabolism, we also discuss this crosstalk in relation to sex differences in BAT activity.
Asunto(s)
Tejido Adiposo Pardo/fisiología , Glucocorticoides/metabolismo , Hormonas Esteroides Gonadales/metabolismo , Factores Sexuales , Adipocitos Marrones/citología , Andrógenos/metabolismo , Animales , Diabetes Mellitus Tipo 2/metabolismo , Femenino , Homeostasis , Humanos , Sistema Hipotálamo-Hipofisario/metabolismo , Metabolismo de los Lípidos , Lípidos/química , Masculino , Ratones , Obesidad/complicaciones , Ratas , Caracteres Sexuales , TermogénesisRESUMEN
High uncoupling protein 1 (Ucp1) expression is a characteristic of differentiated brown adipocytes and is linked to adipogenic differentiation. Paracrine fibroblast growth factor 8b (FGF8b) strongly induces Ucp1 transcription in white adipocytes independent of adipogenesis. Here, we report that FGF8b and other paracrine FGFs act on brown and white preadipocytes to upregulate Ucp1 expression via a FGFR1-MEK1/2-ERK1/2 axis, independent of adipogenesis. Transcriptomic analysis revealed an upregulation of prostaglandin biosynthesis and glycolysis upon Fgf8b treatment of preadipocytes. Oxylipin measurement by LC-MS/MS in FGF8b conditioned media identified prostaglandin E2 as a putative mediator of FGF8b induced Ucp1 transcription. RNA interference and pharmacological inhibition of the prostaglandin E2 biosynthetic pathway confirmed that PGE2 is causally involved in the control over Ucp1 transcription. Importantly, impairment of or failure to induce glycolytic flux blunted the induction of Ucp1, even in the presence of PGE2 . Lastly, a screening of transcription factors identified Nrf1 and Hes1 as required regulators of FGF8b induced Ucp1 expression. Thus, we conclude that paracrine FGFs co-regulate prostaglandin and glucose metabolism to induce Ucp1 expression in a Nrf1/Hes1-dependent manner in preadipocytes, revealing a novel regulatory network in control of Ucp1 expression in a formerly unrecognized cell type.
Asunto(s)
Adipocitos Marrones/metabolismo , Adipocitos Blancos/metabolismo , Dinoprostona/metabolismo , Factor 8 de Crecimiento de Fibroblastos/metabolismo , Regulación de la Expresión Génica , Glucólisis , Proteína Desacopladora 1/fisiología , Adipocitos Marrones/citología , Adipocitos Blancos/citología , Adipogénesis , Animales , Células Cultivadas , Factor 8 de Crecimiento de Fibroblastos/genética , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones NoqueadosRESUMEN
Brown adipose tissue (BAT) is responsible for non-shivering thermogenesis in mammals, and brown adipocytes (BAs) are the functional units of BAT. BAs contain both multilocular lipid droplets and abundant mitochondria, and they express uncoupling protein 1 (UCP1). BAs are categorized into two sub-types based on their origin: embryo derived classical BAs (cBAs) and white adipocytes derived BAs. Due to their relatively low density, BAs cannot be isolated from BAT with traditional centrifugation method. In this study, a new method was developed to isolate BAs from mice for gene and protein expression analysis. In this protocol, interscapular BAT from adult mice was digested with Collagenase and Dispase solution, and the dissociated BAs were enriched with 6% iodixanol solution. Isolated BAs were then lysed with Trizol reagent for simultaneous isolation of RNA, DNA, and protein. After RNA isolation, the organic phase of the lysate was used for protein extraction. Our data showed that 6% iodixanol solution efficiently enriched BAs without interfering with follow-up gene and protein expression studies. Platelet-derived growth factor (PDGF) is a growth factor that regulates the growth and proliferation of mesenchymal cells. Compared to the brown adipose tissue, isolated BAs had significantly higher expression of Pdgfa. In summary, this new method provides a platform for studying the biology of brown adipocytes at a single cell-type level.