RESUMEN
The central nervous system has been implicated in the age-induced reduction in adipose tissue lipolysis. However, the underlying mechanisms remain unclear. Here, we show the expression of SLC7A14 is reduced in proopiomelanocortin (POMC) neurons of aged mice. Overexpression of SLC7A14 in POMC neurons alleviates the aging-reduced lipolysis, whereas SLC7A14 deletion mimics the age-induced lipolysis impairment. Metabolomics analysis reveals that POMC SLC7A14 increased taurochenodeoxycholic acid (TCDCA) content, which mediates the SLC7A14 knockout- or age-induced WAT lipolysis impairment. Furthermore, SLC7A14-increased TCDCA content is dependent on intestinal apical sodium-dependent bile acid transporter (ASBT), which is regulated by intestinal sympathetic afferent nerves. Finally, SLC7A14 regulates the intestinal sympathetic afferent nerves by inhibiting mTORC1 signaling through inhibiting TSC1 phosphorylation. Collectively, our study suggests the function for central SLC7A14 and an upstream mechanism for the mTORC1 signaling pathway. Moreover, our data provides insights into the brain-gut-adipose tissue crosstalk in age-induced lipolysis impairment.
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Tejido Adiposo Blanco , Envejecimiento , Sistema de Transporte de Aminoácidos y+ , Hipotálamo , Lipólisis , Animales , Masculino , Ratones , Tejido Adiposo Blanco/metabolismo , Envejecimiento/metabolismo , Sistema de Transporte de Aminoácidos y+/metabolismo , Sistema de Transporte de Aminoácidos y+/genética , Hipotálamo/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina/metabolismo , Ratones Endogámicos C57BL , Ratones Noqueados , Neuronas/metabolismo , Proopiomelanocortina/metabolismo , Proopiomelanocortina/genética , Transducción de Señal , Simportadores/metabolismo , Simportadores/genéticaRESUMEN
Gut microbiota is linked to human metabolic diseases. The previous work showed that leucine deprivation improved metabolic dysfunction, but whether leucine deprivation alters certain specific species of bacterium that brings these benefits remains unclear. Here, this work finds that leucine deprivation alters gut microbiota composition, which is sufficient and necessary for the metabolic improvements induced by leucine deprivation. Among all the affected bacteria, B. coccoides is markedly increased in the feces of leucine-deprived mice. Moreover, gavage with B. coccoides improves insulin sensitivity and reduces body fat in high-fat diet (HFD) mice, and singly colonization of B. coccoides increases insulin sensitivity in gnotobiotic mice. The effects of B. coccoides are mediated by metabolizing tryptophan into indole-3-acetic acid (I3AA) that activates the aryl hydrocarbon receptor (AhR) in the liver. Finally, this work reveals that reduced fecal B. coccoides and I3AA levels are associated with the clinical metabolic syndrome. These findings suggest that B. coccoides is a newly identified bacterium increased by leucine deprivation, which improves metabolic disorders via metabolizing tryptophan into I3AA.
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Modelos Animales de Enfermedad , Microbioma Gastrointestinal , Leucina , Ratones Endogámicos C57BL , Animales , Ratones , Leucina/metabolismo , Microbioma Gastrointestinal/fisiología , Microbioma Gastrointestinal/genética , Masculino , Enfermedades Metabólicas/metabolismo , Enfermedades Metabólicas/microbiología , Dieta Alta en Grasa , Resistencia a la Insulina/fisiología , Triptófano/metabolismo , Ácidos Indolacéticos/metabolismo , Heces/microbiología , Clostridiales/metabolismo , Clostridiales/genética , HumanosRESUMEN
This paper investigated the effects of twin-screw extrusion treatment on the formation, structure and properties of yam starch-gallic acid complexes. Yam starch and gallic acid were extruded. The microstructure, gelatinization characteristics, and rheological properties of the samples were determined. The microstructure of extruded yam starch-gallic acid complexes presented a rough granular morphology, low swelling, and high solubility. The X-ray diffraction analysis showed that the extruded yam starch-gallic acid complexes exhibited A + V-type crystalline structure. Fourier transform infrared spectroscopy results showed that the extrusion treatment could destroy the internal orderly structure of yam starch, and the addition of gallic acid could further reduce its molecular orderliness. Differential scanning calorimetry analysis showed a decrease in the enthalpy of gelatinization of the sample. Dynamic rheological analysis showed that the storage modulus and loss modulus of the extruded yam starch-gallic acid complexes were significantly reduced, exhibiting a weak gel system. The results of viscosity showed that extrusion synergistic gallic acid reduced the peak viscosity and setback value of starch. In addition, extrusion treatment had an inhibitory effect on the digestibility of yam starch, and enhanced the interaction of gallic acid with yam starch or hydrolytic enzymes. Therefore, extrusion synergistic gallic acid has improved the structure and properties of yam starch-related products, which can provide new directions and new ideas for the development of yam starch.
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Dioscorea , Almidón , Almidón/química , Dioscorea/química , Solubilidad , Hidrólisis , ViscosidadRESUMEN
Chronic stress induces depression- and anxiety-related behaviors, which are common mental disorders accompanied not only by dysfunction of the brain but also of the intestine. Activating transcription factor 4 (ATF4) is a stress-induced gene, and we previously show that it is important for gut functions; however, the contribution of the intestinal ATF4 to stress-related behaviors is not known. Here, we show that chronic stress inhibits the expression of ATF4 in gut epithelial cells. ATF4 overexpression in the colon relieves stress-related behavioral alterations in male mice, as measured by open-field test, elevated plus-maze test, and tail suspension test, whereas intestine-specific ATF4 knockout induces stress-related behavioral alterations in male mice. Furthermore, glutamatergic neurons are inhibited in the paraventricular thalamus (PVT) of two strains of intestinal ATF4-deficient mice, and selective activation of these neurons alleviates stress-related behavioral alterations in intestinal ATF4-deficient mice. The highly expressed gut-secreted peptide trefoil factor 3 (TFF3) is chosen from RNA-Seq data from ATF4 deletion mice and demonstrated decreased in gut epithelial cells, which is directly regulated by ATF4. Injection of TFF3 reverses stress-related behaviors in ATF4 knockout mice, and the beneficial effects of TFF3 are blocked by inhibiting PVT glutamatergic neurons using DREADDs. In summary, this study demonstrates the function of ATF4 in the gut-brain regulation of stress-related behavioral alterations, via TFF3 modulating PVT neural activity. This research provides evidence of gut signals regulating stress-related behavioral alterations and identifies possible drug targets for the treatment of stress-related behavioral disorders.
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Factor de Transcripción Activador 4 , Tálamo , Masculino , Animales , Ratones , Factor de Transcripción Activador 4/metabolismo , Tálamo/metabolismo , Neuronas/metabolismo , Ratones Noqueados , Colon/metabolismoRESUMEN
An important role for liver in the regulation of adipose tissue thermogenesis upon cold exposure has been suggested; however, the underlying mechanisms remain incompletely defined. Here, we identify elevated serum bradykinin levels in response to acute cold exposure in male mice. A bolus of anti-bradykinin antibodies reduces body temperature during acute cold exposure, whereas bradykinin has the opposite effect. We demonstrate that bradykinin induces brown adipose tissue thermogenesis and white adipose tissue browning, and bradykinin increases uncoupling protein 1 (UCP1) expression in adipose tissue. The bradykinin B2 receptor (B2R), adrenergic signaling and nitric oxide signaling are involved in regulating bradykinin-increased UCP1 expression. Moreover, acute cold exposure inhibits hepatic prolyl endopeptidase (PREP) activity, causing reduced liver bradykinin degradation and increased serum bradykinin levels. Finally, by blocking the breakdown of bradykinin, angiotensin-converting enzyme inhibitors (ACEIs) increase serum bradykinin levels and induce brown adipose tissue thermogenesis and white adipose tissue browning via B2R. Collectively, our data provide new insights into the mechanisms underlying organ crosstalk in whole-body physiology control during cold exposure and also suggest bradykinin as a possible anti-obesity target.
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Tejido Adiposo Blanco , Obesidad , Ratones , Masculino , Animales , Tejido Adiposo Blanco/metabolismo , Obesidad/metabolismo , Tejido Adiposo Pardo/metabolismo , Termogénesis , Hígado/metabolismo , Proteína Desacopladora 1/genética , Proteína Desacopladora 1/metabolismo , Frío , Ratones Endogámicos C57BLRESUMEN
BACKGROUND AND AIMS: The incidence of inflammatory bowel disease [IBD] in the elderly has increased in recent years. However, the mechanisms underlying the ageing-related IBD susceptibility remain elusive. Cytokine-inducible SH2-containing protein [CISH] is involved in regulating metabolism, the expansion of intestinal tuft cells and type-2 innate lymphoid cells, and ageing-related airway inflammation. Here, we investigated the role of CISH in ageing-related colitis susceptibility. METHODS: CISH and phosphorylated signal transducer and activator of transcription-3 [p-STAT3] levels were evaluated in the colons of ageing mice and older ulcerative colitis [UC] patients. Mice with intestinal epithelial cell-specific knockout of Cish [CishΔIEC] and Cish-floxed mice were administered dextran sodium sulphate [DSS] or trinitrobenzene sulphonic acid [TNBS] to induce colitis. Colonic tissues were analysed in quantitative real-time polymerase chain reaction, immunoblotting, immunohistochemical, and histological staining experiments. Differentially expressed genes from colonic epithelia were analysed by RNA sequencing. RESULTS: Ageing increased the severity of DSS-induced colitis and the expression of colonic epithelial CISH in mice. CishΔIEC prevented DSS- or TNBS-induced colitis in middle-aged mice but not in young mice. RNA-sequencing analysis revealed that CishΔIEC significantly suppressed DSS-induced oxidative stress and proinflammatory responses. During ageing in the CCD841 cell model, knockdown of CISH decreased ageing-induced oxidative stress and proinflammatory responses, whereas these effects were compromised by knocking down or inhibiting STAT3. The increase in CISH expression was higher in the colonic mucosa of older patients with UC than in that of healthy controls. CONCLUSIONS: CISH might be a proinflammatory regulator in ageing; therefore, targeted therapy against CISH may provide a novel strategy for treating ageing-related IBD.
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Colitis Ulcerosa , Colitis , Enfermedades Inflamatorias del Intestino , Ratones , Animales , Inmunidad Innata , Linfocitos/metabolismo , Colitis/inducido químicamente , Colitis/genética , Colitis/metabolismo , Colitis Ulcerosa/inducido químicamente , Colitis Ulcerosa/genética , Colitis Ulcerosa/metabolismo , Colon/patología , Células Epiteliales/metabolismo , Mucosa Intestinal/patología , Enfermedades Inflamatorias del Intestino/patología , Envejecimiento/genética , Citocinas/metabolismo , Sulfato de Dextran/farmacología , Ratones Endogámicos C57BL , Modelos Animales de EnfermedadRESUMEN
Lysosomal amino acid accumulation is implicated in several diseases, but its role in insulin resistance, the central mechanism to type 2 diabetes and many metabolic diseases, is unclear. In this study, we show the hepatic expression of lysosomal membrane protein solute carrier family 7 member 14 (SLC7A14) is increased in insulin-resistant mice. The promoting effect of SLC7A14 on insulin resistance is demonstrated by loss- and gain-of-function experiments. SLC7A14 is further demonstrated as a transporter resulting in the accumulation of lysosomal γ-aminobutyric acid (GABA), which induces insulin resistance via inhibiting mTOR complex 2 (mTORC2)'s activity. These results establish a causal link between lysosomal amino acids and insulin resistance and suggest that SLC7A14 inhibition may provide a therapeutic strategy in treating insulin resistance-related and GABA-related diseases and may provide insights into the upstream mechanisms for mTORC2, the master regulator in many important processes.
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Diabetes Mellitus Tipo 2 , Resistencia a la Insulina , Ratones , Animales , Diabetes Mellitus Tipo 2/metabolismo , Diana Mecanicista del Complejo 2 de la Rapamicina/metabolismo , Aminoácidos/metabolismo , Ácido gamma-Aminobutírico/metabolismo , Lisosomas/metabolismoRESUMEN
Psychiatric disorders, such as anxiety, are associated with inflammatory bowel disease (IBD), however, the neural mechanisms regulating this comorbidity are unknown. Here, we show that hypothalamic agouti-related protein (AgRP) neuronal activity is suppressed under chronic restraint stress (CRS), a condition known to increase anxiety and colitis susceptibility. Consistently, chemogenic activation or inhibition of AgRP neurons reverses or mimics CRS-induced increase of anxiety-like behaviors and colitis susceptibility, respectively. Furthermore, CRS inhibits AgRP neuronal activity by suppressing the expression of c-Jun. Moreover, overexpression of c-Jun in these neurons protects against the CRS-induced effects, and knockdown of c-Jun in AgRP neurons (c-Jun∆AgRP) promotes anxiety and colitis susceptibility. Finally, the levels of secreted protein thrombospondin 1 (THBS1) are negatively associated with increased anxiety and colitis, and supplementing recombinant THBS1 rescues colitis susceptibility in c-Jun∆AgRP mice. Taken together, these results reveal critical roles of hypothalamic AgRP neuron-derived c-Jun in orchestrating stress-induced anxiety and colitis susceptibility.
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Colitis , Hipotálamo , Ratones , Animales , Proteína Relacionada con Agouti/genética , Proteína Relacionada con Agouti/metabolismo , Hipotálamo/metabolismo , Ansiedad/etiología , Neuronas/fisiología , Colitis/genética , Colitis/metabolismoRESUMEN
Impairment of gluconeogenesis is a key factor responsible for hyperglycemia in patients with type 2 diabetes. As an important member of the suppressors of cytokine signaling (SOCS) protein family, many physiological functions of cytokine-inducible SH2-containing protein (CISH) have been described; however, the role of hepatic CISH in gluconeogenesis is poorly understood. In the present study, we observed that hepatic CISH expression was reduced in fasted wild-type (WT) mice. Overexpression of CISH decreased glucose production in mouse primary hepatocytes, while silencing of CISH had the opposite effects. In addition, adenovirus-mediated hepatic CISH overexpression resulted in improved glucose tolerance and decreased gluconeogenesis in WT and leptin receptor-deficient diabetic (db/db) mice. In contrast, adenovirus-mediated hepatic CISH knockdown impaired glucose tolerance and increased gluconeogenesis in WT mice. We also generated liver-specific CISH knockout (LV-CISH KO) mice and discovered that these mice had a similar phenotype in glucose tolerance and gluconeogenesis as mice injected with adenoviruses that knockdown CISH expression. Mechanistically, we found that CISH overexpression decreased and CISH knockdown increased the mRNA and protein levels of glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase 1 (PEPCK), two key enzymes involved in gluconeogenesis, in vitro, and in vivo. Moreover, we discovered that the phosphorylation of cAMP-responsive element binding protein 1 (CREB), a transcription factor of G6pase and Pepck, was required for regulating gluconeogenesis by CISH. Taken together, this study identifies hepatic CISH as an important regulator of gluconeogenesis. Our results also provide important insights into the metabolic functions of the SOCS protein family and the potential targets for the treatment of diabetes.
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Proteína de Unión a Elemento de Respuesta al AMP Cíclico/metabolismo , Gluconeogénesis , Proteínas Supresoras de la Señalización de Citocinas/metabolismo , Animales , Citocinas/metabolismo , Diabetes Mellitus Tipo 2/metabolismo , Glucosa/metabolismo , Glucosa-6-Fosfatasa/genética , Hepatocitos/metabolismo , Hígado/metabolismo , Ratones , Ratones Endogámicos C57BLRESUMEN
Angiotensin-converting enzyme 2 (ACE2) has been identified as a primary receptor for severe acute respiratory syndrome coronaviruses 2 (SARS-CoV-2). Here, we investigated the expression regulation of ACE2 in enterocytes under amino acid deprivation conditions. In this study, we found that ACE2 expression was upregulated upon all or single essential amino acid deprivation in human colonic epithelial CCD841 cells. Furthermore, we found that knockdown of general control nonderepressible 2 (GCN2) reduced intestinal ACE2 mRNA and protein levels in vitro and in vivo. Consistently, we revealed two GCN2 inhibitors, GCN2iB and GCN2-IN-1, downregulated ACE2 protein expression in CCD841 cells. Moreover, we found that increased ACE2 expression in response to leucine deprivation was GCN2 dependent. Through RNA-sequencing analysis, we identified two transcription factors, MAFB and MAFF, positively regulated ACE2 expression under leucine deprivation in CCD841 cells. These findings demonstrate that amino acid deficiency increases ACE2 expression and thereby likely aggravates intestinal SARS-CoV-2 infection.
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Aminoácidos , Enzima Convertidora de Angiotensina 2 , COVID-19 , Enterocitos , Proteínas Serina-Treonina Quinasas , Aminoácidos/deficiencia , Aminoácidos/metabolismo , Enzima Convertidora de Angiotensina 2/biosíntesis , Enzima Convertidora de Angiotensina 2/genética , Enzima Convertidora de Angiotensina 2/metabolismo , COVID-19/enzimología , COVID-19/genética , COVID-19/virología , Enterocitos/enzimología , Enterocitos/metabolismo , Humanos , Leucina/farmacología , Peptidil-Dipeptidasa A/fisiología , Proteínas Serina-Treonina Quinasas/antagonistas & inhibidores , Proteínas Serina-Treonina Quinasas/genética , Proteínas Serina-Treonina Quinasas/metabolismo , SARS-CoV-2/metabolismoRESUMEN
Chronic inflammation in liver induces insulin resistance systemically and in other tissues, including the skeletal muscle (SM); however, the underlying mechanisms remain largely unknown. RNA sequencing of primary hepatocytes from wild-type mice fed long-term high-fat diet (HFD), which have severe chronic inflammation and insulin resistance revealed that the expression of hepatokine endoplasmic reticulum aminopeptidase 1 (ERAP1) was upregulated by a HFD. Increased ERAP1 levels were also observed in interferon-γ-treated primary hepatocytes. Furthermore, hepatic ERAP1 overexpression attenuated systemic and SM insulin sensitivity, whereas hepatic ERAP1 knockdown had the opposite effects, with corresponding changes in serum ERAP1 levels. Mechanistically, ERAP1 functions as an antagonist-like factor, which interacts with ß2 adrenergic receptor (ADRB2) and reduces its expression by decreasing ubiquitin-specific peptidase 33-mediated deubiquitination and thereby interrupts ADRB2-stimulated insulin signaling in the SM. The findings of this study indicate ERAP1 is an inflammation-induced hepatokine that impairs SM insulin sensitivity. Its inhibition may provide a therapeutic strategy for insulin resistance-related diseases, such as type 2 diabetes.
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Diabetes Mellitus Tipo 2 , Resistencia a la Insulina , Aminopeptidasas/genética , Aminopeptidasas/metabolismo , Animales , Diabetes Mellitus Tipo 2/metabolismo , Dieta Alta en Grasa/efectos adversos , Inflamación/metabolismo , Resistencia a la Insulina/genética , Ratones , Ratones Endogámicos C57BL , Antígenos de Histocompatibilidad Menor/metabolismo , Músculo Esquelético/metabolismoRESUMEN
Leucine deprivation improves insulin sensitivity; however, whether and how this effect can be extended are unknown. We hypothesized that intermittent leucine deprivation (ILD) might produce a long-term effect on improved insulin sensitivity via the formation of metabolic memory. Consistently, seven ILD cycles of treatment (1-day leucine-deficient diet, 3-day control diet) in mice produced a long-lasting (after a control diet was resumed for 49 days) effect on improved whole-body and hepatic insulin sensitivity in mice, indicating the potential formation of metabolic memory. Furthermore, the effects of ILD depended on hepatic general control nondepressible 2 (GCN2) expression, as verified by gain- and loss-of-function experiments. Moreover, ILD increased Gcn2 expression by reducing its DNA methylation at two CpG promoter sites controlled by demethylase growth arrest and DNA damage inducible b. Finally, ILD also improved insulin sensitivity in insulin-resistant mice. Thus, ILD induces long-lasting improvements in insulin sensitivity by increasing hepatic Gcn2 expression via a reduction in its DNA methylation. These results provide novel insights into understanding of the link between leucine deprivation and insulin sensitivity, as well as potential nutritional intervention strategies for treating insulin resistance and related diseases. We also provide evidence for liver-specific metabolic memory after ILD and novel epigenetic mechanisms for Gcn2 regulation.
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Resistencia a la Insulina , Leucina/deficiencia , Hígado/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Animales , Células Cultivadas , Epigénesis Genética/efectos de los fármacos , Femenino , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Insulina/metabolismo , Resistencia a la Insulina/genética , Leucina/farmacología , Hígado/efectos de los fármacos , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Serina-Treonina Quinasas/metabolismo , Transducción de SeñalRESUMEN
We have previously shown that leucine deprivation stimulates browning and lipolysis in white adipose tissue (WAT), which helps to treat obesity. Adipose tissue macrophages (ATMs) significantly influence WAT browning and lipolysis. However, it is unclear whether ATMs are involved in leucine deprivation-induced browning and lipolysis in WAT; the associated signals remain to be elucidated. Here, we investigated the role of ATMs and the possible mechanisms involved in WAT browning and lipolysis under leucine-deprivation conditions. In this study, macrophages were depleted in mice by injecting clodronate-liposomes (CLOD) into subcutaneous white adipose tissues. Then, mice lacking general control nonderepressible 2 kinase (GCN2), which is a sensor of amino acid starvation, specifically in Lyz2-expressing cells, were generated to investigate the changes in leucine deprivation-induced WAT browning and lipolysis. We found leucine deprivation decreased the accumulation and changed the polarization of ATMs. Ablation of macrophages by CLOD impaired WAT browning and lipolysis under leucine-deprivation conditions. Mechanistically, leucine deprivation activated GCN2 signals in macrophages. Myeloid-specific abrogation of GCN2 in mice blocked leucine deprivation-induced browning and lipolysis in WAT. Further analyses revealed that GCN2 activation in macrophages reduced the expression of monoamine oxidase A (MAOA), resulting in increased norepinephrine (NE) secretion from macrophages to adipocytes, and this resulted in enhanced WAT browning and lipolysis. Moreover, the injection of CL316,243, a ß3-adrenergic receptor agonist, and inhibition of MAOA effectively increased the level of NE, leading to the enhancement of browning and lipolysis of WAT in myeloid GCN2 knockout mice under leucine deprivation. Collectively, our results demonstrate a novel function of GCN2 signals in macrophages, that is, regulating WAT browning and lipolysis under leucine deprivation. Our study provides important hints for possible treatment for obesity.
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Adipocitos/metabolismo , Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Blanco/metabolismo , Leucina/deficiencia , Lipólisis , Macrófagos/metabolismo , Proteínas Serina-Treonina Quinasas/fisiología , Animales , Metabolismo Energético , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , TermogénesisRESUMEN
BACKGROUND: Leucine deprivation modulates the dietary amino acid composition, reducing the fat content and improving the glucose tolerance, thus protecting the organism against obesity. However, a complete deprivation of leucine can lead to an extremely rapid fat loss in mice, accompanied by prolonged adverse effects such as weakness and mental fatigue. Therefore, in this study we aimed to seek the optimal concentration of dietary leucine that can reduce fat mass and improve the metabolism without the onset of severe effects. METHODS: To investigate whether there is a better concentration of diet leucine restriction (LR), based on the diet we conducted (A10021B), that can reduce fat mass and improve metabolism status without taking many negative effects, we fed 8 weeks old male C57Bl/6J mice with increasing degrees of leucine restriction diet 0% LR (control group), 25% LR, 50% LR, and 75% LR groups (4-6 mice each group). Fat mass and blood glucose levels were measured. The expression levels of genes involved in lipid metabolism in white adipose tissue (WAT) and liver, and proteins in insulin signaling were assessed in WAT, liver and muscle. RESULTS: We found that the 50% LR group is the most proper group here at the lowest leucine effective concentration, which reduced fat mass (p < 0.05) and improved glucose regulation in mice over a 90 days feeding. Further studies revealed that lipid synthesis pathway (Fas, Scd1and Srebp1, p < 0.05) was downregulated and lipolysis (Atgl, p < 0.05) was upregulated in WAT in 50% LR group, compared to that in control group. Furthermore, glucose regulation (glucose tolerance test, p < 0.05) was also improved, and insulin signaling (p < 0.05) in the muscle was enhanced in 50% LR group while in WAT and liver were not changed. CONCLUSIONS: Collectively, a 50% LR in mice reduced fat mass and improved glucose regulation, which may function through modulating lipid synthesis and lipolysis pathway in adipose tissue as well as enhancing insulin signaling in muscle. So far, we provide a further consideration for carrying out the diet of leucine restriction to reduce fat and improve metabolism status before clinical study.
RESUMEN
OBJECTIVE: Although the hypothalamus is crucial for peripheral metabolism control, the signals in specific neurons involved remain poorly understood. The aim of our current study was to explore the role of the hypothalamic gene mothers against decapentaplegic homolog 7 (Smad7) in peripheral glucose disorders. METHODS: We studied glucose metabolism in high-fat diet (HFD)-fed mice and middle-aged mice with Cre-mediated recombination causing 1) overexpression of Smad7 in hypothalamic proopiomelanocortin (POMC) neurons, 2) deletion of Smad7 in POMC neurons, and 3) overexpression of protein kinase B (AKT) in arcuate nucleus (ARC) in Smad7 overexpressed mice. Intracerebroventricular (ICV) cannulation of insulin was used to test the hypothalamic insulin sensitivity in the mice. Hypothalamic primary neurons were used to investigate the mechanism of Smad7 regulating hypothalamic insulin signaling. RESULTS: We found that Smad7 expression was increased in POMC neurons in the hypothalamic ARC of HFD-fed or middle-aged mice. Furthermore, overexpression of Smad7 in POMC neurons disrupted the glucose balance, and deletion of Smad7 in POMC neurons prevented diet- or age-induced glucose disorders, which was likely to be independent of changes in body weight or food intake. Moreover, the effect of Smad7 was reversed by overexpression of AKT in the ARC. Finally, Smad7 decreased AKT phosphorylation by activating protein phosphatase 1c in hypothalamic primary neurons. CONCLUSIONS: Our results demonstrated that an excess of central Smad7 in POMC neurons disrupts glucose balance by attenuating hypothalamic insulin signaling. In addition, we found that this regulation was mediated by the activity of protein phosphatase 1c.
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Glucosa/metabolismo , Proopiomelanocortina/metabolismo , Proteína smad7/metabolismo , Animales , Núcleo Arqueado del Hipotálamo/metabolismo , Dieta Alta en Grasa , Metabolismo Energético , Expresión Génica/genética , Regulación de la Expresión Génica/genética , Hipotálamo/metabolismo , Insulina/metabolismo , Resistencia a la Insulina/fisiología , Leptina/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Neuronas/metabolismo , Obesidad/metabolismo , Proopiomelanocortina/genética , Proteínas Proto-Oncogénicas c-akt/metabolismo , Transducción de Señal , Proteína smad7/genéticaRESUMEN
The browning of white adipose tissue (WAT) has got much attention for its potential beneficial effects on metabolic disorders, however, the nutritional factors and neuronal signals involved remain largely unknown. We sought to investigate whether WAT browning is stimulated by leucine deprivation, and whether the amino acid sensor, general control non-derepressible 2 (GCN2), in amygdalar protein kinase C-δ (PKC-δ) neurons contributes to this regulation. Our results show that leucine deficiency can induce WAT browning, which is unlikely to be caused by food intake, but is largely blocked by PKC-δ neuronal inhibition and amygdalar GCN2 deletion. Furthermore, GCN2 knockdown in amygdalar PKC-δ neurons blocks WAT browning, which is reversed by over-expression of amino acid responsive gene activating transcription factor 4 (ATF4), and is mediated by the activities of amygdalar PKC-δ neurons and the sympathetic nervous system. Our data demonstrate that GCN2/ATF4 can regulate WAT browning in amygdalar PKC-δ neurons under leucine deprivation.
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Factor de Transcripción Activador 4/metabolismo , Tejido Adiposo Blanco/fisiología , Amígdala del Cerebelo/fisiología , Leucina/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Tejido Adiposo Pardo/fisiología , Tejido Adiposo Blanco/inervación , Amígdala del Cerebelo/citología , Animales , Técnicas de Silenciamiento del Gen , Lipólisis/fisiología , Masculino , Ratones , Ratones Noqueados , Neuronas/metabolismo , Proteína Quinasa C-delta/metabolismo , Proteínas Serina-Treonina Quinasas/genética , Transducción de Señal/fisiología , Técnicas Estereotáxicas , Sistema Nervioso Simpático/fisiología , Termogénesis/fisiologíaRESUMEN
The mechanisms underlying glucocorticoid (GC)-increased adiposity are poorly understood. Brown adipose tissue (BAT) acquires white adipose tissue (WAT) cell features defined as BAT whitening under certain circumstances. The aim of our current study was to investigate the possibility and mechanisms of GC-induced BAT whitening. Here, we showed that one-week dexamethasone (Dex) treatment induced BAT whitening, characterized by lipid droplet accumulation, in vitro and in vivo. Furthermore, autophagy and ATG7 (autophagy related 7) expression was induced in BAT by Dex, and treatment with the autophagy inhibitor chloroquine or adenovirus-mediated ATG7 knockdown prevented Dex-induced BAT whitening and fat mass gain. Moreover, Dex-increased ATG7 expression and autophagy was mediated by enhanced expression of BTG1 (B cell translocation gene 1, anti-proliferative) that stimulated activity of CREB1 (cAMP response element binding protein 1). The importance of BTG1 in this regulation was further demonstrated by the observed BAT whitening in adipocyte-specific BTG1-overexpressing mice and the attenuated Dex-induced BAT whitening and fat mass gain in mice with BTG1 knockdown in BAT. Taken together, we showed that Dex induces a significant whitening of BAT via BTG1- and ATG7-dependent autophagy, which might contribute to Dex-increased adiposity. These results provide new insights into the mechanisms underlying GC-increased adiposity and possible strategy for preventing GC-induced side effects via the combined use of an autophagy inhibitor.Abbreviations: ACADL: acyl-Coenzyme A dehydrogenase, long-chain; ACADM: acyl-Coenzyme A dehydrogenase, medium-chain; ACADS: acyl-Coenzyme A dehydrogenase, short-chain; ADIPOQ: adiponectin; AGT: angiotensinogen; Atg: autophagy-related; BAT: brown adipose tissue; BTG1: B cell translocation gene 1, anti-proliferative; CEBPA: CCAAT/enhancer binding protein (C/EBP), alpha; CIDEA: cell death-inducing DNA fragmentation factor, alpha subunit-like effector A; CPT1B: carnitine palmitoyltransferase 1b, muscle; CPT2: carnitine palmitoyltransferase 2; CQ: chloroquine; Dex: dexamethasone; eWAT: epididymal white adipose tissue; FABP4: fatty acid binding protein 4, adipocyte; FFAs: free fatty acids; GCs: glucocorticoids; NRIP1: nuclear receptor interacting protein 1; OCR: oxygen consumption rate; PBS: phosphate-buffered saline; PPARA: peroxisome proliferator activated receptor alpha; PPARG: peroxisome proliferator activated receptor gamma; PPARGC1A: peroxisome proliferator activated receptor, gamma, coactivator 1 alpha; PRDM16: PR domain containing 16; PSAT1: phosphoserine aminotransferase 1; RB1: RB transcriptional corepressor 1; RBL1/p107: RB transcriptional corepressor like 1; SQSTM1: sequestosome 1; sWAT: subcutaneous white adipose tissue; TG: triglycerides; UCP1: uncoupling protein 1 (mitochondrial, proton carrier); WT: wild-type.
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Tejido Adiposo Pardo/metabolismo , Tejido Adiposo Blanco/metabolismo , Adiposidad/efectos de los fármacos , Autofagia , Glucocorticoides/farmacología , Adipogénesis/efectos de los fármacos , Tejido Adiposo Pardo/efectos de los fármacos , Tejido Adiposo Blanco/efectos de los fármacos , Animales , Animales Recién Nacidos , Proteína 7 Relacionada con la Autofagia/genética , Proteína 7 Relacionada con la Autofagia/metabolismo , Línea Celular , Proteína de Unión a Elemento de Respuesta al AMP Cíclico/metabolismo , Dexametasona/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Técnicas de Silenciamiento del Gen , Humanos , Lípidos/química , Masculino , Ratones Endogámicos C57BL , Ratones Transgénicos , Proteínas de Neoplasias/genética , Proteínas de Neoplasias/metabolismoRESUMEN
OBJECTIVE: c-Jun, a prominent member of the activator protein 1 (AP-1) family, is involved in various physiology processes such as cell death and survival. However, a role of hepatic c-Jun in the whole-body metabolism is poorly understood. METHODS: We generated liver-specific c-Jun knock-out (c-junâ³li) mice to investigate the effect of hepatic c-Jun on the whole-body physiology, particularly in blood glucose and body temperature. Primary hepatocytes were also used to explore a direct regulation of c-Jun in gluconeogenesis. RESULTS: c-junâ³li mice showed higher hepatic gluconeogenic capacity compared with control mice, and similar results were obtained in vitro. In addition, fibroblast growth factor 21 (FGF21) expression was directly inhibited by c-Jun knockdown and adenovirus-mediated hepatic FGF21 over-expression blocked the effect of c-Jun on gluconeogenesis in c-junâ³li mice. Interestingly, c-junâ³li mice also exhibited higher body temperature, with induced thermogenesis and uncoupling protein 1 (UCP1) expression in brown adipose tissue (BAT). Furthermore, the body temperature became comparable between c-junâ³li and control mice at thermoneutral temperature (30 °C). Moreover, the activity of sympathetic nervous system (SNS) was increased in c-junâ³li mice and the higher body temperature was inhibited by beta-adrenergic receptor blocker injection. Finally, the activated SNS and increased body temperature in c-junâ³li mice was most likely caused by the signals from the brain and hepatic vagus nerve, as the expression of c-Fos (the molecular marker of neuronal activation) was changed in several brain areas controlling body temperature and body temperature was decreased by selective hepatic vagotomy. CONCLUSIONS: These data demonstrate a novel function of hepatic c-Jun in the regulation of gluconeogenesis and body temperature via FGF21 and neural signals. Our results also provide novel insights into the organ crosstalk in the regulation of the whole-body physiology.
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Temperatura Corporal , Factores de Crecimiento de Fibroblastos/metabolismo , Gluconeogénesis , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Hígado/metabolismo , Nervio Vago/efectos de los fármacos , Tejido Adiposo/metabolismo , Antagonistas Adrenérgicos beta/farmacología , Animales , Células Cultivadas , Células Hep G2 , Humanos , Proteínas Quinasas JNK Activadas por Mitógenos/genética , Masculino , Ratones , Propranolol/farmacología , Transducción de SeñalRESUMEN
BACKGROUND & AIMS: Activating transcription factor 4 (ATF4) regulates genes involved in the inflammatory response, amino acid metabolism, autophagy, and endoplasmic reticulum stress. We investigated whether its activity is altered in patients with inflammatory bowel diseases (IBDs) and mice with enterocolitis. METHODS: We obtained biopsy samples during endoscopy from inflamed and/or uninflamed regions of the colon from 21 patients with active Crohn's disease (CD), 22 patients with active ulcerative colitis (UC), and 38 control individuals without IBD and of the ileum from 19 patients with active CD and 8 individuals without IBD in China. Mice with disruption of Atf4 specifically in intestinal epithelial cells (Atf4ΔIEC mice) and Atf4-floxed mice (controls) were given dextran sodium sulfate (DSS) to induce colitis. Some mice were given injections of recombinant defensin α1 (DEFA1) and supplementation of l-alanyl-glutamine or glutamine in drinking water. Human and mouse ileal and colon tissues were analyzed by quantitative real-time polymerase chain reaction, immunoblots, and immunohistochemistry. Serum and intestinal epithelial cell (IEC) amino acids were measured by high-performance liquid chromatography-tandem mass spectrometry. Levels of ATF4 were knocked down in IEC-18 cells with small interfering RNAs. Microbiomes were analyzed in ileal feces from mice by using 16S ribosomal DNA sequencing. RESULTS: Levels of ATF4 were significantly decreased in inflamed intestinal mucosa from patients with active CD or active UC compared with those from uninflamed regions or intestinal mucosa from control individuals. ATF4 was also decreased in colonic epithelia from mice with colitis vs mice without colitis. Atf4ΔIEC mice developed spontaneous enterocolitis and colitis of greater severity than control mice after administration of DSS. Atf4ΔIEC mice had decreased serum levels of glutamine and reduced levels of antimicrobial peptides, such as Defa1, Defa4, Defa5, Camp, and Lyz1, in ileal Paneth cells. Atf4ΔIEC mice had alterations in ileal microbiomes compared with control mice; these changes were reversed by administration of glutamine. Injections of DEFA1 reduced the severity of spontaneous enteritis and DSS-induced colitis in Atf4ΔIEC mice. We found that expression of solute carrier family 1 member 5 (SLC1A5), a glutamine transporter, was directly regulated by ATF4 in cell lines. Overexpression of SLC1A5 in IEC-18 or primary IEC cells increased glutamine uptake and expression of antimicrobial peptides. Knockdown of ATF4 in IEC-18 cells increased expression of inflammatory cytokines, whereas overexpression of SLC1A5 in the knockdown cells reduced cytokine expression. Levels of SLC1A5 were decreased in inflamed intestinal mucosa of patients with CD and UC and correlated with levels of ATF4. CONCLUSIONS: Levels of ATF4 are decreased in inflamed intestinal mucosa from patients with active CD or UC. In mice, ATF4 deficiency reduces glutamine uptake by intestinal epithelial cells and expression of antimicrobial peptides by decreasing transcription of Slc1a5. ATF4 might therefore be a target for the treatment of IBD.
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Factor de Transcripción Activador 4/deficiencia , Péptidos Catiónicos Antimicrobianos/metabolismo , Colitis Ulcerosa/metabolismo , Enfermedad de Crohn/metabolismo , Glutamina/metabolismo , Factor de Transcripción Activador 4/genética , Factor de Transcripción Activador 4/metabolismo , Adolescente , Adulto , Sistema de Transporte de Aminoácidos ASC/genética , Sistema de Transporte de Aminoácidos ASC/metabolismo , Animales , Estudios de Casos y Controles , Línea Celular , Colitis/inducido químicamente , Colitis/metabolismo , Colitis Ulcerosa/sangre , Colitis Ulcerosa/patología , Colon/citología , Colon/metabolismo , Enfermedad de Crohn/sangre , Enfermedad de Crohn/patología , Células Epiteliales , Femenino , Técnicas de Silenciamiento del Gen , Glutamina/sangre , Glutamina/farmacología , Humanos , Íleon/citología , Íleon/metabolismo , Íleon/microbiología , Mucosa Intestinal/metabolismo , Masculino , Ratones , Microbiota/efectos de los fármacos , Persona de Mediana Edad , Antígenos de Histocompatibilidad Menor/genética , Antígenos de Histocompatibilidad Menor/metabolismo , Células de Paneth/metabolismo , Adulto JovenRESUMEN
Although the central nervous system has been implicated in glucocorticoid-induced gain of fat mass, the underlying mechanisms are poorly understood. The aim of this study was to investigate the possible involvement of hypothalamic serum- and glucocorticoid-regulated kinase 1 (SGK1) in glucocorticoid-increased adiposity. It is well known that SGK1 expression is induced by acute glucocorticoid treatment, but it is interesting that we found its expression to be decreased in the arcuate nucleus of the hypothalamus, including proopiomelanocortin (POMC) neurons, following chronic dexamethasone (Dex) treatment. To study the role of SGK1 in POMC neurons, we produced mice that developed or experienced adult-onset SGK1 deletion in POMC neurons (PSKO). As observed in Dex-treated mice, PSKO mice exhibited increased adiposity and decreased energy expenditure. Mice overexpressing constitutively active SGK1 in POMC neurons consistently had the opposite phenotype and did not experience Dex-increased adiposity. Finally, Dex decreased hypothalamic α-melanocyte-stimulating hormone (α-MSH) content and its precursor Pomc expression via SGK1/FOXO3 signaling, and intracerebroventricular injection of α-MSH or adenovirus-mediated FOXO3 knockdown in the arcuate nucleus largely reversed the metabolic alterations in PSKO mice. These results demonstrate that POMC SGK1/FOXO3 signaling mediates glucocorticoid-increased adiposity, providing new insights into the mechanistic link between glucocorticoids and fat accumulation and important hints for possible treatment targets for obesity.