RESUMO
Excess glucocorticoid (GC) signaling in adipose tissue is a key driver of insulin resistance and hepatic steatosis, but underlying mechanisms have not been fully elucidated. Signal transducer and activator of transcription 5 (STAT5) signaling in adipocytes has also been implicated in the progression of similar metabolic disturbances. Although STAT5 has been shown to interact with the glucocorticoid receptor (GR) in many cell types including adipocytes, the relevance of the STAT5/GR complex has not been investigated in adipocytes. Adult male and female adipocyte-specific STAT5 knockout (STAT5AKO) and floxed mice were given corticosterone (CORT) or vehicle in their drinking water for 1 wk and examined for differences in their metabolic responses to GC excess. CORT-induced lipolysis, insulin resistance, and changes in body composition were comparable between genotypes and in both sexes. Adipocyte STAT5 is not necessary for GC-mediated progression of metabolic disease.NEW & NOTEWORTHY Both STAT5 and glucocorticoid receptor contribute to metabolic processes and type 2 diabetes, in large part, due to their functions in adipocytes. These two transcription factors can form a complex and function together. Our novel studies determined the role of adipocyte STAT5 in glucocorticoid-induced diabetes. We observed that STAT5 in adipocytes is not needed for glucocorticoid-induced diabetes.
Assuntos
Diabetes Mellitus Tipo 2 , Resistência à Insulina , Doenças Metabólicas , Fator de Transcrição STAT5 , Animais , Feminino , Masculino , Camundongos , Adipócitos/metabolismo , Corticosterona/farmacologia , Corticosterona/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Glucocorticoides/efeitos adversos , Glucocorticoides/metabolismo , Glucocorticoides/farmacologia , Resistência à Insulina/genética , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismo , Fator de Transcrição STAT5/genética , Fator de Transcrição STAT5/metabolismo , Doenças Metabólicas/induzido quimicamente , Doenças Metabólicas/genéticaRESUMO
Herbal remedies are increasing in popularity as treatments for metabolic conditions such as obesity and Type 2 Diabetes. One potential therapeutic option is fenugreek seeds (Trigonella foenum-graecum), which have been used for treating high cholesterol and Type 2 diabetes. A proposed mechanism for these benefits is through alterations in the microbiome, which impact mammalian host metabolic function. This study used untargeted metabolomics to investigate the fenugreek-induced alterations in the intestinal, liver, and serum profiles of mice fed either a 60% high-fat or low-fat control diet each with or without fenugreek supplementation (2% w/w) for 14 weeks. Metagenomic analyses of intestinal contents found significant alterations in the relative composition of the gut microbiome resulting from fenugreek supplementation. Specifically, Verrucomicrobia, a phylum containing beneficial bacteria which are correlated with health benefits, increased in relative abundance with fenugreek. Metabolomics partial least squares discriminant analysis revealed substantial fenugreek-induced changes in the large intestines. However, it was observed that while the magnitude of changes was less, significant modifications were present in the liver tissues resulting from fenugreek supplementation. Further analyses revealed metabolic processes affected by fenugreek and showed broad ranging impacts in multiple pathways, including carnitine biosynthesis, cholesterol and bile acid metabolism, and arginine biosynthesis. These pathways may play important roles in the beneficial effects of fenugreek.
Assuntos
Diabetes Mellitus Tipo 2 , Microbioma Gastrointestinal , Trigonella , Animais , Colesterol , Diabetes Mellitus Tipo 2/tratamento farmacológico , Suplementos Nutricionais , Mamíferos , Camundongos , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêuticoRESUMO
Two new diprenylated coumaric acid isomers (1a and 1b) and two known congeners, capillartemisin A (2) and B (3), were isolated from Artemisia scoparia as bioactive markers using bioactivity-guided HPLC fractionation. Their structures were determined by spectroscopic means, including 1D and 2D NMR methods and LC-MS, with their purity assessed by 1D 1H pure shift qNMR spectroscopic analysis. The bioactivity of compounds was evaluated by enhanced accumulation of lipids, as measured using Oil Red O staining, and by increased expression of several adipocyte marker genes, including adiponectin in 3T3-L1 adipocytes relative to untreated negative controls. Compared to the plant's 80% EtOH extract, these purified compounds showed significant but still weaker inhibition of TNFα-induced lipolysis in 3T3-L1 adipocytes. This suggests that additional bioactive substances are responsible for the multiple metabolically favorable effects on adipocytes observed with Artemisia scoparia extract.
Assuntos
Adipócitos/efeitos dos fármacos , Adipogenia/efeitos dos fármacos , Artemisia/química , Ácidos Cumáricos/farmacologia , Células 3T3-L1 , Adiponectina/metabolismo , Animais , Ácidos Cumáricos/isolamento & purificação , Lipólise/efeitos dos fármacos , Camundongos , Compostos Fitoquímicos/isolamento & purificação , Compostos Fitoquímicos/farmacologia , Prenilação , Fator de Necrose Tumoral alfa/metabolismoRESUMO
STAT5 proteins play a role in adipocyte development and function, but their specific functions are largely unknown. To this end, we used an unbiased MS-based approach to identify novel STAT5-interacting proteins. We observed that STAT5A bound the E1ß and E2 subunits of the pyruvate dehydrogenase complex (PDC). Whereas STAT5A typically localizes to the cytosol or nucleus, PDC normally resides within the mitochondrial matrix where it converts pyruvate to acetyl-CoA. We employed affinity purification and immunoblotting to validate the interaction between STAT5A and PDC subunits in murine and human cultured adipocytes, as well as in adipose tissue. We found that multiple PDC subunits interact with hormone-activated STAT5A in a dose- and time-dependent manner that coincides with tyrosine phosphorylation of STAT5. Using subcellular fractionation and immunofluorescence microscopy, we observed that PDC-E2 is present within the adipocyte nucleus where it associates with STAT5A. Because STAT5A is a transcription factor, we used chromatin immunoprecipitation (ChIP) to assess PDC's ability to interact with STAT5 DNA-binding sites. These analyses revealed that PDC-E2 is bound to a STAT5-binding site in the promoter of the STAT5 target gene cytokine-inducible SH2-containing protein (cish). We have demonstrated a compelling interaction between STAT5A and PDC subunits in adipocytes under physiological conditions. There is previous evidence that PDC localizes to cancer cell nuclei where it plays a role in histone acetylation. On the basis of our ChIP data and these previous findings, we hypothesize that PDC may modulate STAT5's ability to regulate gene expression by controlling histone or STAT5 acetylation.
Assuntos
Tecido Adiposo/metabolismo , Complexo Piruvato Desidrogenase/metabolismo , Fator de Transcrição STAT5/metabolismo , Células 3T3-L1 , Tecido Adiposo/citologia , Animais , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fosforilação , Ligação ProteicaRESUMO
An ethanolic extract of Artemisia scoparia (SCO) has metabolically favorable effects on adipocyte development and function in vitro and in vivo. In diet-induced obese mice, SCO supplementation significantly reduced fasting glucose and insulin levels. Given the importance of adipocyte lipolysis in metabolic health, we hypothesized that SCO modulates lipolysis in vitro and in vivo. Free fatty acids and glycerol were measured in the sera of mice fed a high-fat diet with or without SCO supplementation. In cultured 3T3-L1 adipocytes, the effects of SCO on lipolysis were assessed by measuring glycerol and free fatty acid release. Microarray analysis, qPCR, and immunoblotting were used to assess gene expression and protein abundance. We found that SCO supplementation of a high-fat diet in mice substantially reduces circulating glycerol and free fatty acid levels, and we observed a cell-autonomous effect of SCO to significantly attenuate tumor necrosis factor-α (TNFα)-induced lipolysis in cultured adipocytes. Although several prolipolytic and antilipolytic genes were identified by microarray analysis of subcutaneous and visceral adipose tissue from SCO-fed mice, regulation of these genes did not consistently correlate with SCO's ability to reduce lipolytic metabolites in sera or cell culture media. However, in the presence of TNFα in cultured adipocytes, SCO induced antilipolytic changes in phosphorylation of hormone-sensitive lipase and perilipin. Together, these data suggest that the antilipolytic effects of SCO on adipose tissue play a role in the ability of this botanical extract to improve whole body metabolic parameters and support its use as a dietary supplement to promote metabolic resiliency.
Assuntos
Adipócitos/efeitos dos fármacos , Artemisia , Lipólise/efeitos dos fármacos , Extratos Vegetais/farmacologia , Células 3T3-L1 , Adipócitos/metabolismo , Animais , Células Cultivadas , Ácidos Graxos não Esterificados/sangue , Glicerol/sangue , Camundongos , Perilipina-1/metabolismo , Fosforilação/efeitos dos fármacos , Esterol Esterase/metabolismo , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
Adiponectin is a hormone secreted from adipocytes that plays an important role in insulin sensitivity and protects against metabolic syndrome. Growth hormone (GH) and prolactin (PRL) are potent STAT5 activators that regulate the expression of several genes in adipocytes. Studies have shown that the secretion of adiponectin from adipose tissue is decreased by treatment with PRL and GH. In this study, we demonstrate that 3T3-L1 adipocytes treated with GH or PRL exhibit a reduction in adiponectin protein levels. Furthermore, we identified three putative STAT5 binding sites in the murine adiponectin promoter and show that only one of these, located at -3,809, binds nuclear protein in a GH- or PRL-dependent manner. Mutation of the STAT5 binding site reduced PRL-dependent protein binding, and supershift analysis revealed that STAT5A and -5B, but not STAT1 and -3, bind to this site in response to PRL. Chromatin immunoprecipitation (IP) analysis demonstrated that only STAT5A, and not STAT1 and -3, bind to the murine adiponectin promoter in a GH-dependent manner in vivo. Adiponectin promoter/reporter constructs were responsive to GH, and chromatin IP analysis reveals that STAT5 binds the adiponectin promoter in vivo following GH stimulation. Overall, these data strongly suggest that STAT5 activators regulate adiponectin transcription through the binding of STAT5 to the -3,809 site that leads to decreased adiponectin expression and secretion. These mechanistic observations are highly consistent with studies in mice and humans that have high GH or PRL levels that are accompanied by lower circulating levels of adiponectin.
Assuntos
Adipócitos/efeitos dos fármacos , Adiponectina/metabolismo , Hormônio do Crescimento/farmacologia , Prolactina/farmacologia , Fator de Transcrição STAT5/metabolismo , Células 3T3-L1 , Adipócitos/metabolismo , Animais , Camundongos , Regiões Promotoras GenéticasRESUMO
Adipocytes play important roles in lipid storage, energy homeostasis and whole body insulin sensitivity. The JAK-STAT (Janus Kinase-Signal Transducer and Activator of Transcription) pathway mediates a variety of physiological processes including development, hematopoiesis, and inflammation. Although the JAK-STAT signaling pathway occurs in all cells, this pathway can mediate cell specific responses. Studies in the last two decades have identified hormones and cytokines that activate the JAK-STAT signaling pathway. These cytokines and hormones have profound effects on adipocytes. The content of this review will introduce the types of adipocytes and immune cells that make up adipose tissue, the impact of obesity on adipose cellular composition and function, and the general constituents of the JAK-STAT pathway and how its activators regulate adipose tissue development and physiology. A summary of the identification of STAT target genes in adipocytes reveals how these transcription factors impact various areas of adipocyte metabolism including insulin action, modulation of lipid stores, and glucose homeostasis. Lastly, we will evaluate exciting new data linking the JAK-STAT pathway and brown adipose tissue and consider the future outlook in this area of investigation. This article is part of a Special Issue entitled: Modulation of Adipose Tissue in Health and Disease.
Assuntos
Tecido Adiposo Marrom/metabolismo , Insulina/metabolismo , Janus Quinases/metabolismo , Fatores de Transcrição STAT/metabolismo , Adipócitos/metabolismo , Metabolismo Energético , Glucose/metabolismo , Humanos , Insulina/fisiologia , Metabolismo dos Lipídeos , Transdução de SinaisRESUMO
Lysine acetyltransferase 8, also known as KAT8, is an enzyme involved in epigenetic regulation, primarily recognized for its ability to modulate histone acetylation. This review presents an overview of KAT8, emphasizing its biological functions, which impact many cellular processes and range from chromatin remodeling to genetic and epigenetic regulation. In many model systems, KAT8's acetylation of histone H4 lysine 16 (H4K16) is critical for chromatin structure modification, which influences gene expression, cell proliferation, differentiation, and apoptosis. Furthermore, this review summarizes the observed genetic variability within the KAT8 gene, underscoring the implications of various single nucleotide polymorphisms (SNPs) that affect its functional efficacy and are linked to diverse phenotypic outcomes, ranging from metabolic traits to neurological disorders. Advanced insights into the structural biology of KAT8 reveal its interaction with multiprotein assemblies, such as the male-specific lethal (MSL) and non-specific lethal (NSL) complexes, which regulate a wide range of transcriptional activities and developmental functions. Additionally, this review focuses on KAT8's roles in cellular homeostasis, stem cell identity, DNA damage repair, and immune response, highlighting its potential as a therapeutic target. The implications of KAT8 in health and disease, as evidenced by recent studies, affirm its importance in cellular physiology and human pathology.
Assuntos
Epigênese Genética , Histona Acetiltransferases , Humanos , Histona Acetiltransferases/metabolismo , Histona Acetiltransferases/genética , Acetilação , Histonas/metabolismo , Histonas/genética , Polimorfismo de Nucleotídeo Único , Animais , Montagem e Desmontagem da CromatinaRESUMO
OBJECTIVE: The objective of this study was to examine the changes in adipose tissue lipolytic capacity and insulin signaling in response to shortened sleep duration (SSD) in postmenopausal women. METHODS: Adipose tissue from a randomized crossover study of nine healthy postmenopausal women (mean [SD], age: 59 [4] years; BMI: 28.0 [2.6] kg/m2) exposed to four nights of habitual and SSD (60% of habitual sleep) while following a eucaloric diet was examined ex vivo. Tissue lipolytic capacity was determined by measurement of secreted glycerol. Cellular insulin signaling was determined by measuring insulin-mediated changes in Akt phosphorylation. RNA sequencing examined global transcriptional changes. RESULTS: With SSD, basal glycerol secretion was reduced, and isoproterenol-stimulated lipolysis was attenuated. Insulin concentration-dependent increases in phosphorylated Akt observed in samples after habitual sleep were abrogated after SSD. However, insulin-mediated suppression of lipolysis remained unaltered with changes in sleep duration. Increased transcription of genes involved in adipogenesis and fatty acid metabolism was observed after SSD. CONCLUSIONS: SSD blunts adrenergic stimulation of lipolysis without altering insulin-mediated suppression of lipolysis in postmenopausal women. These changes in adipose tissue may potentiate fat gain independent of caloric intake. Therefore, interventions promoting sleep may be considered to mitigate abdominal adiposity in postmenopausal women.
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Adipocytes are insulin-sensitive cells that play a major role in energy homeostasis. Obesity is the primary disease of fat cells and a major risk factor for the development of Type 2 diabetes, cardiovascular disease, and metabolic syndrome. The use of botanicals in the treatment of metabolic diseases is an emerging area of research. In previous studies, we screened over 425 botanical extracts for their ability to modulate adipogenesis and insulin sensitivity. We identified St. John's Wort (SJW) extracts as inhibitors of adipogenesis of 3T3-L1 cells and demonstrated that these extracts also inhibited insulin-sensitive glucose uptake in mature fat cells. In these follow-up studies we have further characterized the effects of SJW on insulin action in both murine and human fat cells. We have shown that SJW also attenuates insulin-sensitive glucose uptake in human adipocytes. Moreover, SJW inhibits IRS-1 tyrosine phosphorylation in both murine and human fat cells. Botanical extracts are complex mixtures. Many bioactive compounds have been identified in SJW, including hypericin (HI) and hyperforin (HF). We have examined the ability of HI and HF, purified from SJW, to modulate adipocyte development and insulin action in mature adipocytes. Our novel studies indicate that the profound effects of SJW on adipogenesis, IRS-1 activation, and insulin-stimulated glucose uptake are not mediated by HI and/or HF. Nonetheless, we propose that extracts of SJW may contribute to adipocyte related diseases by limiting differentiation of preadipocytes and significantly inducing insulin resistance in mature fat cells.
Assuntos
Adipócitos/efeitos dos fármacos , Hypericum , Insulina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Células 3T3-L1 , Adipócitos/metabolismo , Animais , Eletroforese em Gel de Poliacrilamida , Humanos , CamundongosRESUMO
Impaired adipocyte function contributes to systemic metabolic dysregulation, and altered fat mass or function increases the risk of Type 2 diabetes. EHMTs 1 and 2 (euchromatic histone lysine methyltransferases 1 and 2), also known as the G9a-like protein (GLP) and G9a, respectively, catalyze the mono- and di-methylation of histone 3 lysine 9 (H3K9) and also methylate nonhistone substrates; in addition, they can act as transcriptional coactivators independent of their methyltransferase activity. These enzymes are known to contribute to adipocyte development and function, and in vivo data indicate a role for G9a and GLP in metabolic disease states; however, the mechanisms involved in the cell-autonomous functions of G9a and GLP in adipocytes are largely unknown. Tumor necrosis factor alpha (TNFα) is a proinflammatory cytokine typically induced in adipose tissue in conditions of insulin resistance and Type 2 diabetes. Using an siRNA approach, we have determined that the loss of G9a and GLP enhances TNFα-induced lipolysis and inflammatory gene expression in adipocytes. Furthermore, we show that G9a and GLP are present in a protein complex with nuclear factor kappa B (NF-κB) in TNFα-treated adipocytes. These novel observations provide mechanistic insights into the association between adipocyte G9a and GLP expression and systemic metabolic health.
RESUMO
OBJECTIVE: The aim of this study was to investigate the effect of sleep restriction (SR) on insulin sensitivity and energy metabolism in postmenopausal women. METHODS: In a randomized crossover trial, 14 women underwent four nights of habitual sleep (HS, 100% normal sleep) and SR (60% of HS) while following a eucaloric diet. Outcomes included the following: (1) insulin sensitivity by hyperinsulinemic-euglycemic clamp, defined as the glucose infusion rate (GIR); (2) resting metabolism and substrate oxidation by indirect calorimetry; and (3) glucose, insulin, and C-peptide concentrations following a standard meal test. RESULTS: Nine postmenopausal women (mean [SD], age 59 [4] years, BMI 28.0 [2.6] kg/m2 ) were analyzed. Accelerometer-determined total time in bed was 8.4 ± 0.6 hours during HS versus 5.0 ± 0.4 hours during SR (38% reduction, p < 0.0001). SR reduced low-dose insulin GIR by 20% (HS: 2.55 ± 0.22 vs. SR: 2.03 ± 0.20 mg/kg/min; p = 0.01) and high-dose insulin GIR by 12% (HS: 10.48 ± 0.72 vs. SR: 9.19 ± 0.72 mg/kg/min; p < 0.001). SR reduced fat oxidation during high-dose insulin infusion (p < 0.01), and it did not alter resting energy metabolism. CONCLUSIONS: Four nights of SR reduced insulin sensitivity and fat oxidation in postmenopausal women. These findings underscore the role of insufficient sleep in metabolic dysfunction following menopause. Larger trials investigating how sleep disturbances cause metabolic dysfunction during menopause are needed across all stages of menopause.
Assuntos
Resistência à Insulina , Humanos , Feminino , Pessoa de Meia-Idade , Pós-Menopausa , Estudos Cross-Over , Sono , Glucose/metabolismo , Metabolismo Energético , Insulina/metabolismo , Glicemia/metabolismoRESUMO
The aggregation of meso-tetra(4-sulfonatophenyl)porphyrin (H(2)TPPS(4-)) in phosphate solutions was investigated as a function of pH, concentration, time, ionic strength, and solution preparation (either from dilution of a freshly prepared 2 mM stock or by direct preparation of µM solution concentrations) using a combination of complementary analytical techniques. UV-vis and fluorescence spectroscopy indicated the formation of staggered, side-by-side (J-type) assemblies. Their size and self-associative behavior were determined using analytical ultracentrifugation and small-angle X-ray scattering. Our results indicate that in neutral and basic solutions of H(2)TPPS(4-), porphyrin dimers and trimers are formed at micromolar concentrations and in the absence of NaCl to screen any ionic interactions. At these low concentrations and pH 4, the protonated H(4)TPPS(2-) species self-assembles, leading to the formation of particularly stable aggregates bearing 25 ± 3 macrocycles. At higher concentrations, these structures further organize or reorganize into tubular, rod-like shapes of various lengths, which were imaged by cryogenic and freeze-fracture transmission electron microscopy. Micron-scale fibrillar aggregates were obtained even at micromolar concentrations at pH 4 when prepared from dilution of a 2 mM stock solution, upon addition of NaCl, or both.
Assuntos
Porfirinas/química , Cloreto de Sódio/química , Água/química , Microscopia Crioeletrônica , Concentração de Íons de Hidrogênio , Microscopia Eletrônica de Transmissão por Filtração de Energia , Estrutura Molecular , Espectrometria de FluorescênciaRESUMO
STATs (Signal Transducers and Activators of Transcription) 5A and 5B are induced during adipocyte differentiation and are primarily activated by growth hormone (GH) and prolactin in fat cells. Previous studies in mice lacking adipocyte GH receptor or STAT5 support their roles in lipolysis-mediated reduction of adipose tissue mass. Male and female mice harboring adipocyte-specific deletion of both STAT5 genes (STAT5AKO) exhibit increased subcutaneous or inguinal adipose tissue mass, but no changes in visceral or gonadal fat mass. Both depots display substantial increases in adipocyte size with no changes in lipolysis in adipose tissue explants. RNA sequencing analysis of subcutaneous adipose tissue and indirect calorimetry experiments reveal sex-dependent differences in adipose gene expression and whole-body energy expenditure, respectively, resulting from the loss of adipocyte STAT5.
Assuntos
Adiposidade , Lipólise , Adipócitos/metabolismo , Tecido Adiposo/metabolismo , Adiposidade/genética , Animais , Feminino , Lipólise/genética , Masculino , Camundongos , Obesidade/genética , Obesidade/metabolismo , Fator de Transcrição STAT5/genéticaRESUMO
Botanicals have a long history of medicinal use for a multitude of ailments, and many modern pharmaceuticals were originally isolated from plants or derived from phytochemicals. Among these, artemisinin, first isolated from Artemisia annua, is the foundation for standard anti-malarial therapies. Plants of the genus Artemisia are among the most common herbal remedies across Asia and Central Europe. The species Artemisia scoparia (SCOPA) is widely used in traditional folk medicine for various liver diseases and inflammatory conditions, as well as for infections, fever, pain, cancer, and diabetes. Modern in vivo and in vitro studies have now investigated SCOPA's effects on these pathologies and its ability to mitigate hepatotoxicity, oxidative stress, obesity, diabetes, and other disease states. This review focuses on the effects of SCOPA that are particularly relevant to metabolic health. Indeed, in recent years, an ethanolic extract of SCOPA has been shown to enhance differentiation of cultured adipocytes and to share some properties of thiazolidinediones (TZDs), a class of insulin-sensitizing agonists of the adipogenic transcription factor PPARγ. In a mouse model of diet-induced obesity, SCOPA diet supplementation lowered fasting insulin and glucose levels, while inducing metabolically favorable changes in adipose tissue and liver. These observations are consistent with many lines of evidence from various tissues and cell types known to contribute to metabolic homeostasis, including immune cells, hepatocytes, and pancreatic beta-cells. Compounds belonging to several classes of phytochemicals have been implicated in these effects, and we provide an overview of these bioactives. The ongoing global epidemics of obesity and metabolic disease clearly require novel therapeutic approaches. While the mechanisms involved in SCOPA's effects on metabolic, anti-inflammatory, and oxidative stress pathways are not fully characterized, current data support further investigation of this plant and its bioactives as potential therapeutic agents in obesity-related metabolic dysfunction and many other conditions.
Assuntos
Artemisia , Scoparia , Animais , Artemisia/química , Artemisia/metabolismo , Insulina/metabolismo , Camundongos , Obesidade/tratamento farmacológico , Compostos Fitoquímicos/farmacologia , Compostos Fitoquímicos/uso terapêutico , Scoparia/metabolismoRESUMO
The Janus kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway has cell-specific functions. Suppressors of cytokine signaling (SOCS) proteins are negative-feedback regulators of JAK-STAT signaling. STAT5 plays a significant role in adipocyte development and function, and bromodomain and extraterminal (BET) proteins may be involved in STAT5 transcriptional activity. We treated 3T3-L1 adipocytes with the BET inhibitor JQ1 and observed that growth hormone (GH)-induced expression of 2 STAT5 target genes from the SOCS family, Socs3 and Cish, were inversely regulated (increased and decreased, respectively) by BET inhibition. Chromatin immunoprecipitation analyses revealed that changes in STAT5 binding did not correlate with gene expression changes. GH promoted the recruitment of the BET protein BRD2 to the Cish, but not Socs3, promoter. JQ1 treatment ablated this effect as well as the GH-induced binding of ribonucleic acid polymerase II (RNA Pol II) to the Cish transcription start site. BRD2 knockdown also suppressed GH induction of Cish, further supporting the role of BRD2 in Cish transcriptional activation. In contrast, JQ1 increased the binding of activated Pol II to the Socs3 coding region, suggesting enhanced messenger RNA (mRNA) elongation. Our finding that JQ1 transiently reduced the interaction between the positive transcription elongation factor (P-TEFb) and its inhibitor hexamethylene bis-acetamide inducible 1 (HEXIM1) is consistent with a previously described off-target effect of JQ1, whereby P-TEFb becomes more available to be recruited by genes that do not depend on BET proteins for activating transcription. These results demonstrate substantially different transcriptional regulation of Socs3 and Cish and suggest distinct roles in adipocytes for these 2 closely related proteins.
Assuntos
Adipócitos/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Hormônio do Crescimento/metabolismo , Proteínas Nucleares/antagonistas & inibidores , Proteína 3 Supressora da Sinalização de Citocinas/metabolismo , Proteínas Supressoras da Sinalização de Citocina/metabolismo , Células 3T3-L1 , Adipócitos/efeitos dos fármacos , Animais , Azepinas , Camundongos , Fator B de Elongação Transcricional Positiva/metabolismo , Proteínas de Ligação a RNA/metabolismo , Fatores de Transcrição/metabolismo , TriazóisRESUMO
OBJECTIVE: The objectives of this study were to assess the role of mitochondrial pyruvate carriers (MPCs) in adipocyte development in vitro and determine whether MPCs are regulated in vivo by high-fat feeding in male and female C57BL/6J mice. METHODS: This study utilized small interfering RNA-mediated knockdown to assess the requirement of MPC1 for adipogenesis in the 3T3-L1 model system. Treatment with UK-5099, a potent pharmacological MPC inhibitor, was also used to assess the loss of MPC activity. Western blot analysis was performed on adipose tissue samples from mice on a low-fat diet or a high-fat diet (HFD) for 12 weeks. RESULTS: The loss of MPC expression via small interfering RNA-mediated knockdown or pharmacological inhibition did not affect adipogenesis of 3T3-L1 cells. In vivo studies indicated that expression of MPCs was significantly decreased in brown adipose tissue of male mice, but not female, on an HFD. CONCLUSIONS: Although MPCs are essential for pyruvate transport, MPCs are not required for adipogenesis in vitro, suggesting that other substrates can be used for energy production when the MPC complex is not functional. Also, a significant decrease in MPC1 and 2 expression occurred in brown fat, but not white fat, of male mice fed an HFD.
Assuntos
Adipogenia/fisiologia , Tecido Adiposo Marrom/metabolismo , Dieta Hiperlipídica/métodos , Transportadores de Ácidos Monocarboxílicos/metabolismo , Obesidade/fisiopatologia , Animais , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BLRESUMO
OBJECTIVE: An ethanolic extract of Artemisia scoparia (SCO) improves adipose tissue function and reduces negative metabolic consequences of high-fat feeding. A. scoparia has a long history of medicinal use across Asia and has anti-inflammatory effects in various cell types and disease models. The objective of the current study was to investigate SCO's effects on inflammation in cells relevant to metabolic health. METHODS: Inflammatory responses were assayed in cultured adipocytes, macrophages, and insulinoma cells by quantitative polymerase chain reaction, immunoblotting, and NF-κB reporter assays. RESULTS: In tumor necrosis factor α-treated adipocytes, SCO mitigated ERK and NF-κB signaling as well as transcriptional responses but had no effect on fatty acid-binding protein 4 secretion. SCO also reduced levels of deleted in breast cancer 1 protein in adipocytes and inhibited inflammatory gene expression in stimulated macrophages. Finally, in pancreatic ß-cells, SCO decreased NF-κB-responsive promoter activity induced by IL-1ß treatment. CONCLUSIONS: SCO's ability to promote adipocyte development and function is thought to mediate its insulin-sensitizing actions in vivo. Our findings that SCO inhibits inflammatory responses through at least two distinct signaling pathways (ERK and NF-κB) in three cell types known to contribute to metabolic disease reveal that SCO may act more broadly than previously thought to improve metabolic health.
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Adipócitos/metabolismo , Anti-Inflamatórios/uso terapêutico , Artemisia/química , Inflamação/tratamento farmacológico , Células Secretoras de Insulina/metabolismo , Macrófagos/metabolismo , Scoparia/química , Animais , Anti-Inflamatórios/farmacologia , Modelos Animais de Doenças , Humanos , Camundongos , TransfecçãoRESUMO
Fenugreek (Trigonella foenum-graecum) is an annual herbaceous plant and a staple of traditional health remedies for metabolic conditions including high cholesterol and diabetes. While the mechanisms of the beneficial actions of fenugreek remain unknown, a role for intestinal microbiota in metabolic homeostasis is likely. To determine if fenugreek utilizes intestinal bacteria to offset the adverse effects of high fat diets, C57BL/6J mice were fed control/low fat (CD) or high fat (HFD) diets each supplemented with or without 2% (w/w) fenugreek for 16 weeks. The effects of fenugreek and HFD on gut microbiota were comprehensively mapped and then statistically assessed in relation to effects on metrics of body weight, hyperlipidemia, and glucose tolerance. 16S metagenomic analyses revealed robust and significant effects of fenugreek on gut microbiota, with alterations in both alpha and beta diversity as well as taxonomic redistribution under both CD and HFD conditions. As previously reported, fenugreek attenuated HFD-induced hyperlipidemia and stabilized glucose tolerance without affecting body weight. Finally, fenugreek specifically reversed the dysbiotic effects of HFD on numerous taxa in a manner tightly correlated with overall metabolic function. Collectively, these data reinforce the essential link between gut microbiota and metabolic syndrome and suggest that the preservation of healthy populations of gut microbiota participates in the beneficial properties of fenugreek in the context of modern Western-style diets.
Assuntos
Dieta Hiperlipídica/efeitos adversos , Microbioma Gastrointestinal/efeitos dos fármacos , Extratos Vegetais/farmacologia , Animais , Bactérias/genética , Glicemia , Peso Corporal/efeitos dos fármacos , Suplementos Nutricionais , Modelos Animais de Doenças , Dislipidemias/prevenção & controle , Glucose/metabolismo , Intolerância à Glucose/prevenção & controle , Hiperlipidemias/tratamento farmacológico , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Obesidade/tratamento farmacológico , Obesidade/microbiologia , Extratos Vegetais/metabolismo , RNA Ribossômico 16S/genética , Trigonella/metabolismoRESUMO
INTRODUCTION: Access to governmental and international nongovernmental sources of health care within eastern Myanmar's conflict regions is virtually nonexistent. Historically, under these circumstances effective care for the victims of trauma, particularly landmine injuries, has been severely deficient. Recognizing this, community-based organizations (CBOs) providing health care in these regions sought to scale up the capacity of indigenous health workers to provide trauma care. CASE DESCRIPTION: The Trauma Management Program (TMP) was developed by CBOs in cooperation with a United States-based health care NGO. The goal of the TMP is to improve the capacity of local health workers to deliver effective trauma care. From 2000 to the present, international and local health care educators have conducted regular workshops to train indigenous health workers in the management of landmine injuries, penetrating and blunt trauma, shock, wound and infection care, and orthopedics. Health workers have been regularly resupplied with the surgical instruments, supplies and medications needed to provide the care learnt through TMP training workshops. DISCUSSION AND EVALUATION: Since 2000, approximately 300 health workers have received training through the TMP, as part of a CBO-run health system providing care for approximately 250,000 internally displaced persons (IDPs) and war-affected residents. Based on interviews with health workers, trauma registry inputs and photo/video documentation, protocols and procedures taught during training workshops have been implemented effectively in the field. Between June 2005 and June 2007, more than 200 patients were recorded in the trauma patient registry. The majority were victims of weapons-related trauma. CONCLUSION: This report illustrates a method to increase the capacity of indigenous health workers to manage traumatic injuries. These health workers are able to provide trauma care for otherwise inaccessible populations in remote and conflicted regions. The principles learnt during the implementation of the TMP might be applied in similar settings.