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1.
J Immunol ; 203(3): 658-664, 2019 08 01.
Artículo en Inglés | MEDLINE | ID: mdl-31201238

RESUMEN

Adipose regulatory T cells (aTregs) have emerged as critical cells for the control of local and systemic inflammation. In this study, we show a distinctive role for the transcriptional regulator Id2 in the differentiation, survival, and function of aTregs in mice. Id2 was highly expressed in aTregs compared with high Id3 expression in lymphoid regulatory T cells (Tregs). Treg-specific deletion of Id2 resulted in a substantial decrease in aTregs, whereas Tregs in the spleen and lymph nodes were unaffected. Additionally, loss of Id2 resulted in decreased expression of aTreg-associated markers, including ST2, CCR2, KLRG1, and GATA3. Gene expression analysis revealed that Id2 expression was essential for the survival of aTregs, and loss of Id2 increased cell death in aTregs due to increased Fas expression. Id2-mediated aTreg depletion resulted in increased systemic inflammation, increased inflammatory macrophages and CD8+ effector T cells, and loss of glucose tolerance under standard diet conditions. Thus, we reveal an unexpected and novel function for Id2 in mediating differentiation, survival, and function of aTregs that when lost result in increased metabolic perturbation.


Asunto(s)
Tejido Adiposo/citología , Proteína 2 Inhibidora de la Diferenciación/genética , Proteína 2 Inhibidora de la Diferenciación/metabolismo , Linfocitos T Reguladores/citología , Linfocitos T Reguladores/metabolismo , Animales , Recuento de Linfocito CD4 , Linfocitos T CD8-positivos/inmunología , Muerte Celular/genética , Diferenciación Celular/genética , Supervivencia Celular/genética , Factor de Transcripción GATA3/metabolismo , Inflamación/inmunología , Proteínas Inhibidoras de la Diferenciación/metabolismo , Proteína 1 Similar al Receptor de Interleucina-1/metabolismo , Lectinas Tipo C/metabolismo , Macrófagos/inmunología , Masculino , Ratones , Ratones Endogámicos C57BL , Receptores CCR2/metabolismo , Receptores Inmunológicos/metabolismo , Linfocitos T Reguladores/inmunología , Receptor fas/metabolismo
2.
J Mol Cell Cardiol ; 129: 174-178, 2019 04.
Artículo en Inglés | MEDLINE | ID: mdl-30822408

RESUMEN

Exposure to a high fat (HF) diet promotes increased fatty acid uptake, fatty acid oxidation and lipid accumulation in the heart. These maladaptive changes impact cellular energy metabolism and may promote the development of cardiac dysfunction. Attempts to increase cardiac glucose utilization have been proposed as a way to reverse cardiomyopathy in obese and diabetic individuals. Adropin is a nutrient-regulated metabolic hormone shown to promote glucose oxidation over fatty acid oxidation in skeletal muscle homogenates in vitro. The focus of the current study was to investigate whether adropin can regulate substrate metabolism in the heart following prolonged exposure to a HF diet in vivo. Mice on a long-term HF diet received serial intraperitoneal injections of vehicle or adropin over three days. Cardiac glucose oxidation was significantly reduced in HF animals, which was rescued by acute adropin treatment. Significant decreases in cardiac pyruvate dehydrogenase activity were observed in HF animals, which were also reversed by adropin treatment. In contrast to previous studies, this change was unrelated to Pdk4 expression, which remained elevated in both vehicle- and adropin-treated HF mice. Instead, we show that adropin modulated the expression of the mitochondrial acetyltransferase enzyme GCN5L1, which altered the acetylation status and activity of fuel metabolism enzymes to favor glucose utilization. Our findings indicate that adropin exposure leads to increased cardiac glucose oxidation under HF conditions, and may provide a future therapeutic avenue in the treatment of diabetic cardiomyopathy.


Asunto(s)
Glucosa/metabolismo , Péptidos y Proteínas de Señalización Intercelular/farmacología , Miocardio/metabolismo , Estado Prediabético/metabolismo , Acetilación/efectos de los fármacos , Animales , Ratones Obesos , Oxidación-Reducción/efectos de los fármacos , Piruvato Deshidrogenasa Quinasa Acetil-Transferidora/metabolismo
3.
J Biol Chem ; 293(46): 17676-17684, 2018 11 16.
Artículo en Inglés | MEDLINE | ID: mdl-30323061

RESUMEN

Sirtuin 3 (SIRT3) deacetylates and activates several mitochondrial fatty acid oxidation enzymes in the liver. Here, we investigated whether the protein acetylase GCN5 general control of amino acid synthesis 5-like 1 (GCN5L1), previously shown to oppose SIRT3 activity, is involved in the regulation of hepatic fatty acid oxidation. We show that GCN5L1 abundance is significantly up-regulated in response to an acute high-fat diet (HFD). Transgenic GCN5L1 overexpression in the mouse liver increased protein acetylation levels, and proteomic detection of specific lysine residues identified numerous sites that are co-regulated by GCN5L1 and SIRT3. We analyzed several fatty acid oxidation proteins identified by the proteomic screen and found that hyperacetylation of hydroxyacyl-CoA dehydrogenase trifunctional multienzyme complex subunit α (HADHA) correlates with increased GCN5L1 levels. Stable GCN5L1 knockdown in HepG2 cells reduced HADHA acetylation and increased activities of fatty acid oxidation enzymes. Mice with a liver-specific deletion of GCN5L1 were protected from hepatic lipid accumulation following a chronic HFD and did not exhibit hyperacetylation of HADHA compared with WT controls. Finally, we found that GCN5L1-knockout mice lack HADHA that is hyperacetylated at three specific lysine residues (Lys-350, Lys-383, and Lys-406) and that acetylation at these sites is significantly associated with increased HADHA activity. We conclude that GCN5L1-mediated regulation of mitochondrial protein acetylation plays a role in hepatic metabolic homeostasis.


Asunto(s)
Ácidos Grasos/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Acetilación , Animales , Dieta Alta en Grasa/efectos adversos , Hígado Graso/prevención & control , Células Hep G2 , Humanos , Lisina/química , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Mitocondriales , Subunidad alfa de la Proteína Trifuncional Mitocondrial/metabolismo , Proteínas del Tejido Nervioso/genética , Oxidación-Reducción , Isoformas de Proteínas/metabolismo , Procesamiento Proteico-Postraduccional , Proteómica , Sirtuina 3/genética
4.
Proc Natl Acad Sci U S A ; 113(26): 7219-24, 2016 06 28.
Artículo en Inglés | MEDLINE | ID: mdl-27307439

RESUMEN

Tre-2/USP6, BUB2, cdc16 domain family member 1 (the TBC domain is the GTPase activating protein domain) (TBC1D1) is a Rab GTPase activating protein that is phosphorylated on Ser(231) by the AMP-activated protein kinase (AMPK) in response to intracellular energy stress. However, the in vivo role and importance of this phosphorylation event remains unknown. To address this question, we generated a mouse model harboring a TBC1D1(Ser231Ala) knockin (KI) mutation and found that the KI mice developed obesity on a normal chow diet. Mechanistically, TBC1D1 is located on insulin-like growth factor 1 (IGF1) storage vesicles, and the KI mutation increases endocrinal and paracrinal/autocrinal IGF1 secretion in an Rab8a-dependent manner. Hypersecretion of IGF1 causes increased expression of lipogenic genes via activating the protein kinase B (PKB; also known as Akt)-mammalian target of rapamycin (mTOR) pathway in adipose tissues, which contributes to the development of obesity, diabetes, and hepatic steatosis as the KI mice age. Collectively, these findings demonstrate that the AMPK-TBC1D1 signaling nexus interacts with the PKB-mTOR pathway via IGF1 secretion, which consequently controls expression of lipogenic genes in the adipose tissue. These findings also have implications for drug discovery to combat obesity.


Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Proteínas Activadoras de GTPasa/metabolismo , Factor I del Crecimiento Similar a la Insulina/metabolismo , Obesidad/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Serina-Treonina Quinasas TOR/metabolismo , Adipocitos/metabolismo , Tejido Adiposo/metabolismo , Animales , Células Cultivadas , Condrocitos/metabolismo , Proteínas Activadoras de GTPasa/genética , Regulación de la Expresión Génica , Glucosa/metabolismo , Células HEK293 , Células Hep G2 , Hepatocitos/metabolismo , Humanos , Hígado/metabolismo , Masculino , Ratones Transgénicos , Contracción Muscular , Músculo Esquelético/metabolismo , Músculo Esquelético/fisiología , Obesidad/genética , Fosforilación , Serina/metabolismo , Triglicéridos/metabolismo
5.
Diabetologia ; 60(2): 336-345, 2017 02.
Artículo en Inglés | MEDLINE | ID: mdl-27826658

RESUMEN

AIMS/HYPOTHESIS: TBC1D1 (tre-2/USP6, BUB2, cdc16 domain family member 1) is a Rab GTPase-activating protein (RabGAP) that has been implicated in regulating GLUT4 trafficking. TBC1D1 can be phosphorylated by the AMP-activated protein kinase (AMPK) on Ser231, which consequently interacts with 14-3-3 proteins. Given the key role for AMPK in regulating insulin-independent muscle glucose uptake, we hypothesised that TBC1D1-Ser231 phosphorylation and/or 14-3-3 binding may mediate AMPK-governed glucose homeostasis. METHODS: Whole-body glucose homeostasis and muscle glucose uptake were assayed in mice bearing a Tbc1d1 Ser231Ala-knockin mutation or harbouring skeletal muscle-specific Ampkα1/α2 (also known as Prkaa1/2) double-knockout mutations in response to an AMPK-activating agent, 5-aminoimidazole-4-carboxamide-1-ß-D-ribofuranoside (AICAR). Exercise-induced muscle glucose uptake and exercise capacity were also determined in the Tbc1d1 Ser231Ala-knockin mice. RESULTS: Skeletal muscle-specific deletion of Ampkα1/a2 in mice prevented AICAR-induced hypoglycaemia and muscle glucose uptake. The Tbc1d1 Ser231Ala-knockin mutation also attenuated the glucose-lowering effect of AICAR in mice. Glucose uptake and cell surface GLUT4 content were significantly lower in muscle isolated from the Tbc1d1 Ser231Ala-knockin mice upon stimulation with a submaximal dose of AICAR. However, this Tbc1d1 Ser231Ala-knockin mutation neither impaired exercise-induced muscle glucose uptake nor affected exercise capacity in mice. CONCLUSIONS/INTERPRETATION: TBC1D1-Ser231 phosphorylation and/or 14-3-3 binding partially mediates AMPK-governed glucose homeostasis and muscle glucose uptake in a context-dependent manner.


Asunto(s)
Aminoimidazol Carboxamida/análogos & derivados , Ejercicio Físico/fisiología , Proteínas Activadoras de GTPasa/genética , Glucosa/metabolismo , Ribonucleótidos/metabolismo , Proteínas 14-3-3/genética , Proteínas 14-3-3/metabolismo , Proteínas Quinasas Activadas por AMP/genética , Proteínas Quinasas Activadas por AMP/metabolismo , Aminoimidazol Carboxamida/metabolismo , Animales , Transporte Biológico , Transportador de Glucosa de Tipo 4/genética , Transportador de Glucosa de Tipo 4/metabolismo , Humanos , Immunoblotting , Inmunoprecipitación , Ratones , Músculo Esquelético/metabolismo , Mutación/genética , Fosforilación , Ribonucleótidos/genética , Transducción de Señal/genética , Transducción de Señal/fisiología
6.
J Biol Chem ; 290(33): 20086-97, 2015 Aug 14.
Artículo en Inglés | MEDLINE | ID: mdl-26112408

RESUMEN

Elevated circulating free fatty acid levels are important contributors to insulin resistance in the muscle and liver, but the underlying mechanisms require further elucidation. Here, we show that geranylgeranyl diphosphate synthase 1 (GGPPS), which is a branch point enzyme in the mevalonic acid pathway, promotes lipid-induced muscle insulin resistance through activation of the RhoA/Rho kinase signaling pathway. We have found that metabolic perturbation would increase GGPPS expression in the skeletal muscles of db/db mice and high fat diet-fed mice. To address the metabolic effects of GGPPS activity in skeletal muscle, we generated mice with specific GGPPS deletions in their skeletal muscle tissue. Heterozygous knock-out of GGPPS in the skeletal muscle improved systemic insulin sensitivity and glucose homeostasis in mice fed both normal chow and high fat diets. These metabolic alterations were accompanied by activated PI3K/Akt signaling and enhanced glucose uptake in the skeletal muscle. Further investigation showed that the free fatty acid-stimulated GGPPS expression in the skeletal muscle was able to enhance the geranylgeranylation of RhoA, which further induced the inhibitory phosphorylation of IRS-1 (Ser-307) by increasing Rho kinase activity. These results implicate a crucial role of the GGPPS/RhoA/Rho kinase/IRS-1 pathway in skeletal muscle, in which it mediates lipid-induced systemic insulin resistance in obese mice. Therefore, skeletal muscle GGPPS may represent a potential pharmacological target for the prevention and treatment of obesity-related type 2 diabetes.


Asunto(s)
Farnesiltransferasa/metabolismo , Resistencia a la Insulina , Metabolismo de los Lípidos , Complejos Multienzimáticos/metabolismo , Músculo Esquelético/metabolismo , Quinasas Asociadas a rho/metabolismo , Proteína de Unión al GTP rhoA/metabolismo , Animales , Diabetes Mellitus Experimental/complicaciones , Diabetes Mellitus Experimental/enzimología , Farnesiltransferasa/genética , Ratones , Complejos Multienzimáticos/genética , Obesidad/complicaciones , Obesidad/enzimología
7.
Biochem J ; 449(2): 479-89, 2013 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-23078342

RESUMEN

AS160 (Akt substrate of 160 kDa) is a Rab GTPase-activating protein implicated in insulin control of GLUT4 (glucose transporter 4) trafficking. In humans, a truncation mutation (R363X) in one allele of AS160 decreased the expression of the protein and caused severe postprandial hyperinsulinaemia during puberty. To complement the limited studies possible in humans, we generated an AS160-knockout mouse. In wild-type mice, AS160 expression is relatively high in adipose tissue and soleus muscle, low in EDL (extensor digitorum longus) muscle and detectable in liver only after enrichment. Despite having lower blood glucose levels under both fasted and random-fed conditions, the AS160-knockout mice exhibited insulin resistance in both muscle and liver in a euglycaemic clamp study. Consistent with this paradoxical phenotype, basal glucose uptake was higher in AS160-knockout primary adipocytes and normal in isolated soleus muscle, but their insulin-stimulated glucose uptake and overall GLUT4 levels were markedly decreased. In contrast, insulin-stimulated glucose uptake and GLUT4 levels were normal in EDL muscle. The liver also contributes to the AS160-knockout phenotype via hepatic insulin resistance, elevated hepatic expression of phosphoenolpyruvate carboxykinase isoforms and pyruvate intolerance, which are indicative of increased gluconeogenesis. Overall, as well as its catalytic function, AS160 influences expression of other proteins, and its loss deregulates basal and insulin-regulated glucose homoeostasis, not only in tissues that normally express AS160, but also by influencing liver function.


Asunto(s)
Tejido Adiposo/metabolismo , Proteínas Activadoras de GTPasa/genética , Resistencia a la Insulina/genética , Músculo Esquelético/metabolismo , Adipocitos/efectos de los fármacos , Adipocitos/metabolismo , Tejido Adiposo/efectos de los fármacos , Animales , Glucemia/metabolismo , Western Blotting , Células Cultivadas , Femenino , Proteínas Activadoras de GTPasa/deficiencia , Glucosa/metabolismo , Glucosa/farmacocinética , Prueba de Tolerancia a la Glucosa , Transportador de Glucosa de Tipo 4/metabolismo , Glucógeno Sintasa Quinasa 3/metabolismo , Humanos , Hipoglucemiantes/sangre , Hipoglucemiantes/farmacología , Técnicas In Vitro , Insulina/sangre , Insulina/farmacología , Hígado/efectos de los fármacos , Hígado/metabolismo , Masculino , Ratones , Ratones Noqueados , Músculo Esquelético/efectos de los fármacos , Fosfoenolpiruvato Carboxiquinasa (GTP)/metabolismo , Fosforilación/efectos de los fármacos
8.
Res Sq ; 2023 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-36711642

RESUMEN

Nonalcoholic fatty liver disease (NAFLD) encompasses a spectrum of pathologies that includes steatosis, steatohepatitis (NASH) and fibrosis and is strongly associated with insulin resistance and type 2 diabetes. Changes in mitochondrial function are implicated in the pathogenesis of NAFLD, particularly in the transition from steatosis to NASH. Mitophagy is a mitochondrial quality control mechanism that allows for the selective removal of damaged mitochondria from the cell via the autophagy pathway. While past work demonstrated a negative association between liver fat content and rates of mitophagy, when changes in mitophagy occur during the pathogenesis of NAFLD and whether such changes contribute to the primary endpoints associated with the disease are currently poorly defined. We therefore undertook the studies described here to establish when alterations in mitophagy occur during the pathogenesis of NAFLD, as well as to determine the effects of genetic inhibition of mitophagy via conditional deletion of a key mitophagy regulator, PARKIN, on the development of steatosis, insulin resistance, inflammation and fibrosis. We find that loss of mitophagy occurs early in the pathogenesis of NAFLD and that loss of PARKIN hastens the onset but not severity of key NAFLD disease features. These observations suggest that loss of mitochondrial quality control in response to nutritional stress may contribute to mitochondrial dysfunction and the pathogenesis of NAFLD.

9.
Sci Rep ; 13(1): 6134, 2023 04 15.
Artículo en Inglés | MEDLINE | ID: mdl-37061564

RESUMEN

G-protein coupled receptors (GPCRs) mediate signal transduction from the cellular surface to intracellular metabolic pathways. While the function of many GPCRs has been delineated previously, a significant number require further characterization to elucidate their cellular function. G-protein coupled receptor 19 (GPR19) is a poorly characterized class A GPCR which has been implicated in the regulation of circadian rhythm, tumor metastasis, and mitochondrial homeostasis. In this report, we use a novel knockout (KO) mouse model to examine the role of GPR19 in whole-body metabolic regulation. We show that loss of GPR19 promotes increased energy expenditure and decreased activity in both male and female mice. However, only male GPR19 KO mice display glucose intolerance in response to a high fat diet. Loss of GPR19 expression in male mice, but not female mice, resulted in diet-induced hepatomegaly, which was associated with decreased expression of key fatty acid oxidation genes in male GPR19 KO livers. Overall, our data suggest that loss of GPR19 impacts whole-body energy metabolism in diet-induced obese mice in a sex-dependent manner.


Asunto(s)
Hígado , Receptores Acoplados a Proteínas G , Masculino , Animales , Ratones , Ratones Noqueados , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Hígado/metabolismo , Metabolismo Energético/genética , Dieta Alta en Grasa/efectos adversos
10.
Cardiovasc Res ; 119(2): 571-586, 2023 03 31.
Artículo en Inglés | MEDLINE | ID: mdl-35704040

RESUMEN

AIMS: Brain-derived neurotrophic factor (BDNF) is markedly decreased in heart failure patients. Both BDNF and its receptor, tropomyosin-related kinase receptor (TrkB), are expressed in cardiomyocytes; however, the role of myocardial BDNF signalling in cardiac pathophysiology is poorly understood. Here, we investigated the role of BDNF/TrkB signalling in cardiac stress response to exercise and pathological stress. METHODS AND RESULTS: We found that myocardial BDNF expression was increased in mice with swimming exercise but decreased in a mouse heart failure model and human failing hearts. Cardiac-specific TrkB knockout (cTrkB KO) mice displayed a blunted adaptive cardiac response to exercise, with attenuated upregulation of transcription factor networks controlling mitochondrial biogenesis/metabolism, including peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α). In response to pathological stress (transaortic constriction, TAC), cTrkB KO mice showed an exacerbated heart failure progression. The downregulation of PGC-1α in cTrkB KO mice exposed to exercise or TAC resulted in decreased cardiac energetics. We further unravelled that BDNF induces PGC-1α upregulation and bioenergetics through a novel signalling pathway, the pleiotropic transcription factor Yin Yang 1. CONCLUSION: Taken together, our findings suggest that myocardial BDNF plays a critical role in regulating cellular energetics in the cardiac stress response.


Asunto(s)
Insuficiencia Cardíaca , Factores de Transcripción , Animales , Humanos , Ratones , Factor Neurotrófico Derivado del Encéfalo/genética , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Metabolismo Energético , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/genética , Coactivador 1-alfa del Receptor Activado por Proliferadores de Peroxisomas gamma/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Factor de Transcripción YY1/metabolismo
11.
Prostate ; 72(3): 244-52, 2012 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-21656835

RESUMEN

BACKGROUND: Interference of androgen receptor (AR) signaling is a target for prostate cancer (CaP) chemoprevention and treatment. We hypothesize that Zyflamend (ZYF) assert its anti-cancer effect by disrupting AR signaling. We also hypothesize that it may act synergistically with the anti-androgen bicalutimde to inhibit CaP cell growth. METHODS: Western blotting, ELISA and reporter assays were done to test ZYF on AR signaling. Semi-quantitative RT-PCR and AR half-life were also examined. Potential synergism between ZYF and bicalutimide were tested via cytotoxicity, colony formation assays, flow cytometry, and Western blotting in the human CAP line, LNCaP and 22RV1. RESULTS: ZYF reduced AR protein, mRNA and protein stability levels in LNCaPs. ZYF also reduced both full-length AR protein and truncated AR protein in the 22Rv1 cell line. Nkx3.1 and PSA were also reduced at the mRNA level. PSA promoter activity and secretion were lower after treatment of cells with ZYF. DHT induction of cell proliferation and AR responsiveness revealed reduction of AR, Nkx3.1, and PSA protein were demonstrated with ZYF treatment. Co-treatment with bicalutimide reducing cell growth, induced apoptosis, and reduced Bcl-2 and BclxL, caspase-3 and PARP. Co-treatment also reduced Nkx3.1 and PSA protein. CONCLUSIONS: These data indicate that ZYF suppresses cell growth mediated by AR signaling, and suggests that the co-treatment with the anti-androgen bicalutimide and ZYF may be a promising approach for cancer therapy and may demonstrate the mechanism of action of ZYF.


Asunto(s)
Adenocarcinoma/patología , Antagonistas de Receptores Androgénicos/farmacología , Anilidas/farmacología , Antineoplásicos/farmacología , Proliferación Celular/efectos de los fármacos , Nitrilos/farmacología , Extractos Vegetales/farmacología , Neoplasias de la Próstata/patología , Receptores Androgénicos/efectos de los fármacos , Compuestos de Tosilo/farmacología , Adenocarcinoma/metabolismo , Caspasa 3/metabolismo , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Sinergismo Farmacológico , Proteínas de Homeodominio/metabolismo , Humanos , Masculino , Antígeno Prostático Específico/metabolismo , Neoplasias de la Próstata/metabolismo , ARN Mensajero/metabolismo , Receptores Androgénicos/metabolismo , Transducción de Señal/efectos de los fármacos , Factores de Transcripción/metabolismo
12.
Curr Res Physiol ; 5: 55-62, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35128468

RESUMEN

Previous studies have shown that treatment with recombinant adropin, a circulating peptide secreted by the liver and brain, restores glucose utilization in the hearts of diet-induced obese mice. This restoration of fuel substrate flexibility, which is lost in obese and diabetic animals, has the potential to improve contractile function in the diabetic heart. Using an ex vivo approach, we examined whether short-term adropin treatment could enhance cardiac function in a mouse model of diet-induced obesity. Our study showed that acute adropin treatment reduces inhibitory phosphorylation of pyruvate dehydrogenase in primary neonatal cardiomyocytes, and leads to moderate improvements in ex vivo cardiac function in mice fed a low fat diet. Conversely, short-term exposure to adropin led to a small decrease in cardiac function in mice fed a long-term high fat diet. Insulin treatment did not significantly alter cardiac function in adropin treated hearts from either low or high fat diet mice, however acute adropin treatment did moderately restore some aspects of downstream insulin signaling in high fat diet fed mice. Overall, these data suggest that in an ex vivo setting, acute adropin treatment alone is not sufficient to promote improved cardiac function in obese animals.

13.
iScience ; 25(12): 105569, 2022 Dec 22.
Artículo en Inglés | MEDLINE | ID: mdl-36465107

RESUMEN

Growth differentiation factor 15 (GDF15) is a stress-induced secreted protein whose circulating levels are increased in the context of obesity. Recombinant GDF15 reduces body weight and improves glycemia in obese models, which is largely attributed to the central action of GDF15 to suppress feeding and reduce body weight. Despite these advances in knowledge, the tissue-specific sites of GDF15 production during obesity are unknown, and the effects of modulating circulating GDF15 levels on insulin sensitivity have not been evaluated directly. Here, we demonstrate that hepatocyte Gdf15 expression is sufficient for changes in circulating levels of GDF15 during obesity and that restoring Gdf15 expression specifically in hepatocytes of Gdf15 knockout mice results in marked improvements in hyperinsulinemia, hepatic insulin sensitivity, and to a lesser extent peripheral insulin sensitivity. These data support that liver hepatocytes are the primary source of circulating GDF15 in obesity.

14.
Physiol Rep ; 10(15): e15415, 2022 08.
Artículo en Inglés | MEDLINE | ID: mdl-35924321

RESUMEN

Left ventricular diastolic dysfunction is a structural and functional condition that precedes the development of heart failure with preserved ejection fraction (HFpEF). The etiology of diastolic dysfunction includes alterations in fuel substrate metabolism that negatively impact cardiac bioenergetics, and may precipitate the eventual transition to heart failure. To date, the molecular mechanisms that regulate early changes in fuel metabolism leading to diastolic dysfunction remain unclear. In this report, we use a diet-induced obesity model in aged mice to show that inhibitory lysine acetylation of the pyruvate dehydrogenase (PDH) complex promotes energetic deficits that may contribute to the development of diastolic dysfunction in mouse hearts. Cardiomyocyte-specific deletion of the mitochondrial lysine acetylation regulatory protein GCN5L1 prevented hyperacetylation of the PDH complex subunit PDHA1, allowing aged obese mice to continue using pyruvate as a bioenergetic substrate in the heart. Our findings suggest that changes in mitochondrial protein lysine acetylation represent a key metabolic component of diastolic dysfunction that precedes the development of heart failure.


Asunto(s)
Cardiomiopatías , Insuficiencia Cardíaca , Proteínas Mitocondriales/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Animales , Dieta Alta en Grasa , Lisina/metabolismo , Ratones , Ratones Endogámicos C57BL , Miocitos Cardíacos/metabolismo , Oxidación-Reducción , Complejo Piruvato Deshidrogenasa/metabolismo , Piruvatos , Volumen Sistólico
15.
Curr Res Physiol ; 5: 232-239, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-35677213

RESUMEN

Sodium-glucose co-transporter type 2 (SGLT2) inhibitor therapy to treat type 2 diabetes unexpectedly reduced all-cause mortality and hospitalization due to heart failure in several large-scale clinical trials, and has since been shown to produce similar cardiovascular disease-protective effects in patients without diabetes. How SGLT2 inhibitor therapy improves cardiovascular disease outcomes remains incompletely understood. Metabolic flexibility refers to the ability of a cell or organ to adjust its use of metabolic substrates, such as glucose or fatty acids, in response to physiological or pathophysiological conditions, and is a feature of a healthy heart that may be lost during diabetic cardiomyopathy and in the failing heart. We therefore undertook studies to determine the effects of SGLT2 inhibitor therapy on cardiac metabolic flexibility in vivo in obese, insulin resistant mice using a [U13C]-glucose infusion during fasting and hyperinsulinemic euglycemic clamp. Relative rates of cardiac glucose versus fatty acid use during fasting were unaffected by EMPA, whereas insulin-stimulated rates of glucose use were significantly increased by EMPA, alongside significant improvements in cardiac insulin signaling. These metabolic effects of EMPA were associated with reduced cardiac hypertrophy and protection from ischemia. These observations suggest that the cardiovascular disease-protective effects of SGLT2 inhibitors may in part be explained by beneficial effects on cardiac metabolic substrate selection.

16.
JCI Insight ; 6(3)2021 02 08.
Artículo en Inglés | MEDLINE | ID: mdl-33351782

RESUMEN

Interleukin-10 (IL-10) is a critical cytokine used by immune cells to suppress inflammation. Paradoxically, immune cell-derived IL-10 can drive insulin resistance in obesity by suppressing adipocyte energy expenditure and thermogenesis. However, the source of IL-10 necessary for the suppression of adipocyte thermogenesis is unknown. We show here that CD4+Foxp3+ regulatory T cells (Tregs) are a substantial source of IL-10 and that Treg-derived IL-10 can suppress adipocyte beiging. Unexpectedly, Treg-specific loss of IL-10 resulted in increased insulin sensitivity and reduced obesity in high-fat diet-fed male mice. Mechanistically, we determined that Treg-specific loss of the transcription factor Blimp-1, a driver of IL-10 expression by Tregs, phenocopied the Treg-specific IL-10-deficient mice. Loss of Blimp-1 expression in Tregs resulted in reduced ST2+KLRG1+, IL-10-secreting Tregs, particularly in the white adipose tissue. Blimp-1-deficient mice were protected from glucose intolerance, insulin resistance, and diet-induced obesity, through increased white adipose tissue browning. Taken together, our data show that Blimp-1-regulated IL-10 secretion by Tregs represses white adipose tissue beiging to maintain adipose tissue homeostasis.


Asunto(s)
Resistencia a la Insulina/inmunología , Resistencia a la Insulina/fisiología , Interleucina-10/inmunología , Obesidad/etiología , Factor 1 de Unión al Dominio 1 de Regulación Positiva/fisiología , Linfocitos T Reguladores/inmunología , Linfocitos T Reguladores/fisiología , Tejido Adiposo Beige/inmunología , Tejido Adiposo Beige/metabolismo , Tejido Adiposo Blanco/inmunología , Tejido Adiposo Blanco/metabolismo , Animales , Dieta Alta en Grasa/efectos adversos , Intolerancia a la Glucosa/inmunología , Intolerancia a la Glucosa/metabolismo , Interleucina-10/deficiencia , Interleucina-10/genética , Masculino , Ratones , Ratones Noqueados , Ratones Transgénicos , Obesidad/inmunología , Obesidad/fisiopatología , Factor 1 de Unión al Dominio 1 de Regulación Positiva/deficiencia , Factor 1 de Unión al Dominio 1 de Regulación Positiva/genética , Termogénesis/inmunología , Termogénesis/fisiología
17.
Sci Rep ; 10(1): 10665, 2020 06 30.
Artículo en Inglés | MEDLINE | ID: mdl-32606301

RESUMEN

Mitochondrial lysine acetylation regulates several metabolic pathways in cardiac cells. The current study investigated whether GCN5L1-mediated lysine acetylation regulates cardiac mitochondrial metabolic proteins in response to a high fat diet (HFD). GCN5L1 cardiac-specific knockout (cKO) mice showed significantly reduced mitochondrial protein acetylation following a HFD relative to wildtype (WT) mice. GCN5L1 cKO mice did not display any decrease in ex vivo cardiac workload in response to a HFD. In contrast, ex vivo cardiac function in HFD-fed WT mice dropped ~ 50% relative to low fat diet (LFD) fed controls. The acetylation status of electron transport chain Complex I protein NDUFB8 was significantly increased in WT mice fed a HFD, but remained unchanged in GCN5L1 cKO mice relative to LFD controls. Finally, we observed that inhibitory acetylation of superoxide dismutase 2 (SOD2) at K122 was increased in WT (but not cKO mice) on a HFD. This correlated with significantly increased cardiac lipid peroxidation in HFD-fed WT mice relative to GCN5L1 cKO animals under the same conditions. We conclude that increased GCN5L1 expression in response to a HFD promotes increased lysine acetylation, and that this may play a role in the development of reactive oxygen species (ROS) damage caused by nutrient excess.


Asunto(s)
Dieta Alta en Grasa/efectos adversos , Mitocondrias/metabolismo , Proteínas Mitocondriales/metabolismo , Miocitos Cardíacos/metabolismo , Proteínas del Tejido Nervioso/metabolismo , Acetilación , Animales , Corazón/fisiología , Peroxidación de Lípido/fisiología , Lisina/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Especies Reactivas de Oxígeno/metabolismo , Superóxido Dismutasa/metabolismo
18.
Mol Metab ; 41: 101051, 2020 11.
Artículo en Inglés | MEDLINE | ID: mdl-32653576

RESUMEN

OBJECTIVE: PARKIN is an E3 ubiquitin ligase that regulates mitochondrial quality control through a process called mitophagy. Recent human and rodent studies suggest that loss of hepatic mitophagy may occur during the pathogenesis of obesity-associated fatty liver and contribute to changes in mitochondrial metabolism associated with this disease. Whole-body Prkn knockout mice are paradoxically protected against diet-induced hepatic steatosis; however, liver-specific effects of Prkn deficiency cannot be discerned in this model due to pleotropic effects of germline Prkn deletion on energy balance and subsequent protection against diet-induced obesity. We therefore generated the first liver-specific Prkn knockout mouse strain (LKO) to directly address the role of hepatic Prkn. METHODS: Littermate control (WT) and LKO mice were fed regular chow (RC) or high-fat diet (HFD) and changes in body weight and composition were measured over time. Liver mitochondrial content was assessed using multiple, complementary techniques, and mitochondrial respiratory capacity was assessed using Oroboros O2K platform. Liver fat was measured biochemically and assessed histologically, while global changes in hepatic gene expression were measured by RNA-seq. Whole-body and tissue-specific insulin resistance were assessed by hyperinsulinemic-euglycemic clamp with isotopic tracers. RESULTS: Liver-specific deletion of Prkn had no effect on body weight or adiposity during RC or HFD feeding; however, hepatic steatosis was increased by 45% in HFD-fed LKO compared with WT mice (P < 0.05). While there were no differences in mitochondrial content between genotypes on either diet, mitochondrial respiratory capacity and efficiency in the liver were significantly reduced in LKO mice. Gene enrichment analyses from liver RNA-seq results suggested significant changes in pathways related to lipid metabolism and fibrosis in HFD-fed Prkn knockout mice. Finally, whole-body insulin sensitivity was reduced by 35% in HFD-fed LKO mice (P < 0.05), which was primarily due to increased hepatic insulin resistance (60% of whole-body effect; P = 0.11). CONCLUSIONS: These data demonstrate that PARKIN contributes to mitochondrial homeostasis in the liver and plays a protective role against the pathogenesis of hepatic steatosis and insulin resistance.


Asunto(s)
Hígado Graso/fisiopatología , Resistencia a la Insulina/genética , Ubiquitina-Proteína Ligasas/metabolismo , Adiposidad , Animales , Peso Corporal/efectos de los fármacos , Dieta Alta en Grasa/efectos adversos , Metabolismo Energético , Hígado Graso/genética , Femenino , Insulina/metabolismo , Resistencia a la Insulina/fisiología , Metabolismo de los Lípidos/genética , Lípidos/fisiología , Hígado/metabolismo , Hígado/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Obesidad/metabolismo , Ubiquitina-Proteína Ligasas/genética
19.
Metabolism ; 107: 154225, 2020 06.
Artículo en Inglés | MEDLINE | ID: mdl-32275973

RESUMEN

BACKGROUND: Caloric restriction (CR) delays the onset of metabolic and age-related disorders. Recent studies have demonstrated that formation of beige adipocytes induced by CR is strongly associated with extracellular remodeling in adipose tissue, decrease in adipose tissue inflammation, and improved systemic metabolic homeostasis. However, beige adipocytes rapidly transition to white upon CR withdrawal through unclear mechanisms. MATERIALS AND METHODS: Six-week old C57BL6 mice were fed with 40% CR chow diet for 6 weeks. Subsequently, one group of mice was switched back to ad libitum chow diet, which was continued for additional 2 weeks. Adipose tissues were assessed histologically and biochemically for beige adipocytes. RESULTS: Beige adipocytes induced by CR rapidly transition to white adipocytes when CR is withdrawn independent of parkin-mediated mitophagy. We demonstrate that the involution of mitochondria during CR withdrawal is strongly linked with a decrease in mitochondrial biogenesis. We further demonstrate that beige-to-white fat transition upon ß3-AR agonist-withdrawal could be attenuated by CR, partly via maintenance of mitochondrial biogenesis. CONCLUSION: In the model of CR, our study highlights the dominant role of mitochondrial biogenesis in the maintenance of beige adipocytes. We propose that loss of beige adipocytes upon ß3-AR agonist withdrawal could be attenuated by CR.


Asunto(s)
Adipocitos Beige/fisiología , Restricción Calórica , Biogénesis de Organelos , Adipocitos Blancos/fisiología , Tejido Adiposo/citología , Agonistas de Receptores Adrenérgicos beta 3/farmacología , Animales , Composición Corporal , Fusión Celular , Dieta , Insulina/sangre , Ratones , Ratones Endogámicos C57BL , Mitofagia , Consumo de Oxígeno , Cultivo Primario de Células
20.
Inflamm Bowel Dis ; 25(10): 1644-1655, 2019 09 18.
Artículo en Inglés | MEDLINE | ID: mdl-31067299

RESUMEN

BACKGROUND: Superoxide dismutase (SOD) is an attractive therapeutic agent to ameliorate oxidative stress that is critical for the initiation and progression of inflammatory bowel disease (IBD). However, the short life of SOD limits its clinical application. In this study, we aim to examine the therapeutic effects of a hyperthermostable SOD from the Thermus thermophilus HB27 (TtSOD) for treatment of experimentally induced IBD. METHODS: A recombinant TtSOD was expressed and purified from Escherichia coli, and its therapeutic effects were examined in 2 experimental IBD animal models. RESULTS: In IBD induced by 2,4,6-trinitrobenzenesulfonic acid in zebrafish, TtSOD treatment decreased intestinal enlargement and attenuated neutrophil infiltration, resulting in alleviation of enterocolitis. In mice, SOD activity was substantially increased in the intestine after oral gavage of TtSOD, which ameliorated gut inflammation, preserved gut barrier function, and attenuated the severity of dextran sulfate sodium-induced colitis. Furthermore, TtSOD inhibited lipopolysaccharide-induced production of reactive oxygen species and inflammatory responses in mouse bone marrow-derived macrophages. CONCLUSIONS: Our results demonstrate that TtSOD possesses therapeutic activities toward experimentally induced IBD, offering new clinical treatment options for patients with IBD.


Asunto(s)
Colitis/inmunología , Inflamación/prevención & control , Macrófagos/inmunología , Estrés Oxidativo/efectos de los fármacos , Especies Reactivas de Oxígeno/metabolismo , Superóxido Dismutasa/metabolismo , Thermus thermophilus/enzimología , Animales , Colitis/inducido químicamente , Colitis/enzimología , Colitis/patología , Sulfato de Dextran/toxicidad , Inflamación/enzimología , Inflamación/etiología , Lipopolisacáridos/toxicidad , Macrófagos/efectos de los fármacos , Macrófagos/enzimología , Macrófagos/patología , Ratones , Ratones Endogámicos C57BL , Infiltración Neutrófila/efectos de los fármacos , Ácido Trinitrobencenosulfónico/toxicidad , Pez Cebra
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