RESUMO
It is now evident that many nuclear hormone receptors can modulate target gene expression. REV-ERBα, one of the nuclear hormone receptors with the capacity to alter clock function, is critically involved in lipid metabolism, adipogenesis, and the inflammatory response. Recent studies suggest that REV-ERBα plays a key role in the mediation between clockwork and inflammation. The purpose of the current study was to investigate the role of REV-ERBα in the regulation of interleukin-6 (il6) gene expression in murine macrophages. REV-ERBα agonists, or overexpression of rev-erb α in the murine macrophage cell line RAW264 cells, suppressed the induction of il6 mRNA following a lipopolysaccharide (LPS) endotoxin challenge. Also, rev-erb α overexpression decreased LPS-stimulated nuclear factor κB (NFκB) activation in RAW264 cells. We showed that REV-ERBα represses il6 expression not only indirectly through an NFκB binding motif but also directly through a REV-ERBα binding motif in the murine il6 promoter region. Furthermore, peritoneal macrophages from mice lacking rev-erb α increased il6 mRNA expression. These data suggest that REV-ERBα regulates the inflammatory response of macrophages through the suppression of il6 expression. REV-ERBα may therefore be identified as a potent anti-inflammatory receptor and be a therapeutic target receptor of inflammatory diseases.
Assuntos
Regulação da Expressão Gênica , Interleucina-6/antagonistas & inibidores , Interleucina-6/biossíntese , Macrófagos Peritoneais/metabolismo , Membro 1 do Grupo D da Subfamília 1 de Receptores Nucleares/metabolismo , Animais , Linhagem Celular , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Regiões Promotoras Genéticas/fisiologia , Ligação Proteica/fisiologiaRESUMO
Recent increases in the number of obese individuals and individuals suffering from lifestyle-related diseases, such as type 2 diabetes, that accompany obesity have become a serious social problem. White adipose tissue (WAT) is more than a mere organ for storage of energy; it is also a highly active metabolic and endocrine organ that secretes physiologically active substances collectively known as adipokines, including tumor necrosis factor-α and adiponectin. Dysregulated expression of adipokines in WAT that is hypertrophied by obesity has been closely associated with the phenomenon of insulin resistance. Therefore, WAT is currently considered to be one of the tissues that promote lifestyle-related diseases. Reduction of excess WAT that results from obesity is seen as an important strategy in preventing and improving lifestyle-related diseases. This review shows that exercise training as well as intake of supplements, such as polyphenols, is one strategy for this, because this regimen can result in reduction of WAT mass, which affects the expression and secretory response of adipokines.
Assuntos
Adiponectina/metabolismo , Tecido Adiposo Branco/metabolismo , Suplementos Nutricionais , Exercício Físico , Estilo de Vida , Obesidade/prevenção & controle , Tecido Adiposo Branco/efeitos dos fármacos , Tecido Adiposo Branco/imunologia , Quimiocina CCL2/metabolismo , Humanos , Obesidade/imunologia , Obesidade/metabolismo , Obesidade/terapia , Polifenóis/administração & dosagem , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Chronic low-level inflammation is associated with obesity and a sedentary lifestyle, causing metabolic disturbances such as insulin resistance. Exercise training has been shown to decrease chronic low-level systemic inflammation in high-fat diet (HFD)-induced obesity. However, the molecular mechanisms mediating its beneficial effects are not fully understood. Ghrelin is a peptide hormone predominantly produced in the stomach that stimulates appetite and induces growth hormone release. In addition to these well-known functions, recent studies suggest that ghrelin localizes to immune cells and exerts an anti-inflammatory effect. The purpose of the current study was to investigate the role of ghrelin expressed in macrophages in the anti-inflammatory effects of voluntary exercise training. Expression of tumor necrosis factor-α (TNF-α), monocyte chemotactic protein (MCP)-1 and F4/80 was increased in adipose tissue from mice fed a HFD (HFD mice) compared with mice fed a standard diet (SD mice), whereas the expression of these inflammatory cytokines was markedly decreased in mice performing voluntary wheel running during the feeding of a HFD (HFEx mice). The expression of TNF-α was also increased in peritoneal macrophages by a HFD and exercise training inhibited the increase of TNF-α expression. Interestingly, expression of ghrelin in peritoneal macrophages was decreased by a HFD and recovered by exercise training. Suppression of ghrelin expression by siRNA increased TNF-α expression and LPS-stimulated NF-κB activation in RAW264 cells, which is a macrophage cell line. TNF-α expression by stimulation with LPS was significantly suppressed in RAW264 cells cultured in the presence of ghrelin. These results suggest that ghrelin exerts potent anti-inflammatory effects in macrophages and functions as a mediator of the beneficial effects of exercise training.
Assuntos
Grelina/fisiologia , Inflamação/terapia , Macrófagos Peritoneais/metabolismo , Obesidade/terapia , Condicionamento Físico Animal , Tecido Adiposo/metabolismo , Animais , Linhagem Celular , Quimiocina CCL2/metabolismo , Grelina/biossíntese , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Fator de Necrose Tumoral alfa/metabolismoRESUMO
It is well known that exercise prevents and reduces cognitive impairment. In the present study, we focused on exercise training as a tool to prevent cognitive impairment, and searched for novel molecules that may relate to the prevention of cognitive impairment in the hippocampus. Two-month-old senescence-accelerated mouse prone-8 (SAMP8) mice were subjected to voluntary exercise training by running on a wheel for 4 months, and were then assigned a conditioned fear memory test. Moreover, various mRNA levels in the hippocampus were examined by DNA array analysis and real-time PCR. Contextual fear memory in SAMP8 control mice was significantly impaired compared with that in non-senescence mice. Exercise training definitely attenuated such cognitive impairment. The results of real-time PCR analysis that was conducted following DNA array analysis in the hippocampus revealed that, compared with SAMR8 control mice, the expression levels of leucine zipper transcription factor-like protein 1 (Lztfl1) mRNA were significantly higher in SAMP8 mice subjected to exercise training. In addition, the overexpression of Lztfl1 promoted neurite outgrowth in Neuro 2a cells. These results suggest that exercise has a preventive effect on cognitive impairment in SAMP8 mice, and that exercise-induced increase in Lztfl1 induces neurite outgrowth.
Assuntos
Transtornos Cognitivos/prevenção & controle , Neuritos/fisiologia , Condicionamento Físico Animal , Fatores de Transcrição/biossíntese , Animais , Hipocampo/metabolismo , Masculino , Memória , Camundongos , Camundongos Mutantes , RNA Mensageiro/biossíntese , RNA Mensageiro/metabolismoRESUMO
The purpose of the present study was to investigate the effect of acute exercise on lipolysis via coordination of hormone-sensitive lipase (HSL) and scaffold proteins, i.e., perilipin A and comparative gene identification-58 (CGI-58), in rat primary adipocytes. Glycerol release was significantly elevated immediately (0h) and three hours (3h) after exercise. Both activity and localization to the pellet of HSL were significantly greater in the pellet fraction, which is included in lipid droplet associated-proteins, than in the supernatant fraction. In the pellet fraction, although neither perilipin A nor CGI-58 protein level changed, level of perilipin A/CGI-58 complex was significantly reduced, accompanied by up-regulated association of perilipin A/HSL at 0h and 3h after exercise. On the other hand, there were no changes in these molecules at 24h after exercise, despite a significant decrease in lipolysis that was observed in response to isoproterenol. These findings suggest that acute exercise enhances lipolysis up to at least 3h after exercise in a manner dependent on modification of HSL and its association with and alteration in scaffold protein.
Assuntos
Adipócitos/enzimologia , Lipólise , Condicionamento Físico Animal , Esterol Esterase/metabolismo , Aciltransferases , Animais , Proteínas de Transporte/biossíntese , Masculino , Perilipina-1 , Fosfoproteínas/biossíntese , Ratos , Ratos WistarRESUMO
Toll-like receptors (TLRs) play an important role in innate immunity while, beta(2)-adrenergic receptors (beta(2)AR) provide the key linkages for the sympathetic nervous system to regulate the immune system. However, their role in macrophages remains uncertain. Here, we demonstrate the cross-talk between beta(2)AR and TLR signalling pathways. Expression of beta(2)AR was down-regulated by TLR4 ligand lipopolysaccharide (LPS) stimulation. To investigate the physiological consequence of this down-regulation RAW264 cells, a macrophage cell line, were transfected with a beta(2)AR expression vector (RAWar). Both LPS-stimulated inducible nitric oxide synthase (NOS II) expression and NO production were markedly suppressed in the RAWar cells. The activation of nuclear factor-kappaB (NF-kappaB) and degradation of the inhibitor of NF-kappaB (IkappaBalpha) in response to LPS were markedly decreased in these cells. The level of beta-arrestin 2, which regulates beta(2)AR signalling, was also reduced in RAW264 cells after stimulation with LPS, but not in RAWar cells. Overexpression of beta-arrestin 2 (RAWarr2) also inhibited NO production and NOS II expression. Furthermore, we demonstrated that beta-arrestin 2 interacted with cytosolic IkappaBalpha and that the level of IkappaBalpha coimmunoprecipitated by anti-beta-arrestin 2 antibodies was decreased in the RAW264 cells but not in RAWar or RAWarr2 cells. These findings suggest that LPS-stimulated signals suppress beta(2)AR expression, leading to down-regulation of beta-arrestin 2 expression, which stabilizes cytosolic IkappaBalpha and inhibits the NF-kappaB activation essential for NOS II expression, probably to ensure rapid and sufficient production of NO in response to microbial attack.
Assuntos
Arrestinas/imunologia , Macrófagos/imunologia , NF-kappa B/metabolismo , Receptores Adrenérgicos beta 2/imunologia , Receptor 4 Toll-Like/imunologia , Animais , Linhagem Celular , Regulação para Baixo/imunologia , Ensaio de Desvio de Mobilidade Eletroforética , Lipopolissacarídeos/imunologia , Camundongos , Óxido Nítrico Sintase Tipo II/metabolismo , Transdução de Sinais/imunologia , beta-Arrestina 2 , beta-ArrestinasRESUMO
Peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha) promotes the expression of oxidative enzymes in skeletal muscle. We hypothesized that activation of the p38 MAPK (mitogen-activated protein kinase) in response to exercise was associated with exercise-induced PGC-1alpha and respiratory enzymes expression and aimed to demonstrate this under the physiological level. We subjected mice to a single bout of treadmill running and found that the exercise induced a biphasic increase in the expression of respiratory enzymes mRNA. The second phase of the increase was accompanied by an increase in PGC-1alpha protein, but the other was not. Administration of SB203580 (SB), an inhibitor of p38 MAPK, suppressed the increase in PGC-1alpha expression and respiratory enzymes mRNA in both phases. These data suggest that p38 MAPK is associated with the exercise-induced expression of PGC-1alpha and biphasic increase in respiratory enzyme mRNAs in mouse skeletal muscle under physiological conditions.
Assuntos
Mitocôndrias/metabolismo , Músculo Esquelético/fisiologia , Condicionamento Físico Animal/métodos , Resistência Física/fisiologia , RNA Mensageiro/metabolismo , Transativadores/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo , Animais , Respiração Celular/fisiologia , Teste de Esforço , Feminino , Camundongos , Camundongos Endogâmicos ICR , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo , Fatores de TranscriçãoRESUMO
The effects of 3-week exercise training on the functions of peritoneal macrophages from BALB/c mice were investigated. Lipopolysaccharide (LPS)-stimulated nitric oxide (NO) and proinflammatory cytokine production in macrophages from trained mice was markedly higher than those from control mice. Meanwhile, exercise training decreased the steady state level of beta(2)-adrenergic receptor (beta(2)AR) mRNA in macrophages. Overexpression of beta(2)AR in the macrophage cell line RAW264 by transfecting with beta(2)AR cDNA suppressed NO synthase (NOS) II expression but dose not influenced proinflammatory cytokine expression. When expression of transfected beta(2)AR in RAWar cells was downregulated by a tetracycline repressor-regulated mammalian expression system, NOS II mRNA expression was significantly increased; this suggested that the changes in the beta(2)AR expression level in macrophages associated with exercise training play a role in the regulation of NO production following LPS stimulation. These findings indicate that exercise training improves macrophage innate immune function in a beta(2)AR-dependent and -independent manner.
Assuntos
Adaptação Fisiológica , Imunidade Inata , Macrófagos Peritoneais/imunologia , Condicionamento Físico Animal , Receptores Adrenérgicos beta 2/metabolismo , Animais , Linhagem Celular , Citocinas/metabolismo , Regulação para Baixo , Lipopolissacarídeos/farmacologia , Macrófagos Peritoneais/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo II/genética , Óxido Nítrico Sintase Tipo II/metabolismo , RNA Mensageiro/metabolismo , Receptores Adrenérgicos beta 2/genética , TransfecçãoRESUMO
In this study we investigated the antioxidative effects of Oligonol (Amino Up Chemical Co., Ltd., Sapporo, Japan), a new polyphenol, in adipocytes. The levels of reactive oxygen species (ROS) and the expression of adipokine genes decreased in HW mouse white adipocytes upon treatment with Oligonol as compared to control cells. The transcriptional activity of nuclear factor-kappaB (NF-kappaB) and the activation of extracellular signal-regulated kinase (ERK) 1/2 were also down-regulated by Oligonol. In addition, when C57BL/6J mice were fed a high fat diet (HFD) for 5 weeks, the levels of epididymal white adipose tissue (WAT) mass and lipid peroxidation in WAT both increased, but Oligonol intake clearly inhibited such HFD-induced increases. Furthermore, dysregulated expression of genes for adipokines in WAT of mice fed solely a HFD was attenuated by Oligonol intake. These results suggest that Oligonol has antioxidative effects and that it attenuates HFD-induced dysregulated expression of genes for adipokines in adipocytes.
Assuntos
Adipócitos/efeitos dos fármacos , Antioxidantes/farmacologia , Catequina/análogos & derivados , Litchi/química , Fenóis/farmacologia , Adipócitos/metabolismo , Animais , Antioxidantes/química , Antioxidantes/metabolismo , Sequência de Bases , Catequina/química , Catequina/metabolismo , Catequina/farmacologia , Diferenciação Celular/efeitos dos fármacos , Linhagem Celular , Primers do DNA , Peroxidação de Lipídeos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Peso Molecular , Fenóis/química , Fenóis/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
PURPOSE: Calcineurin (CaN) signaling pathway has been implicated in the transcriptional regulation of slow muscle fiber genes and in muscle hypertrophy. Our aim was to investigate the functional role of CaN as a regulator of muscle growth and/or muscle fiber type under conditions of recovery from inactivity. METHODS: Female ICR mice (8 wk of age, 28-32 g) were used. To examine the effects of hindlimb suspension (HS) and reloading on skeletal muscle fiber size and muscle fiber type, animals were designated to 8 wk of HS and subsequent reloading for 4 wk. During reloading, animals were treated with pharmacological inhibitors for CaN (FK506) by intraperitoneal administration (3-5 mg.kg.d). After each experimental period, antigravitational soleus muscle was analyzed. RESULTS: HS treatment resulted in obvious muscle atrophy and slow-to-fast fiber-type transformation in the soleus muscle. Subsequent reloading for 4 wk following HS induced muscle regrowth and fiber-type reversion toward a slow profile. FK506 administration prevented this kind of reloading-induced transformation of muscle fiber type. Furthermore, it was confirmed that FK506 administration attenuated maintenance of fiber cross-sectional area and reloading-induced fiber regrowth, specifically in slow-type muscle fibers. CONCLUSION: Reloading-induced fiber-type reversion toward a slow profile is prevented by the pharmacological inhibition of CaN. Additionally, inhibition of CaN prevented maintenance and regrowth of slow-type muscle fibers. These results implicate that the CaN signaling pathway is required in the slow-type muscle fiber program under maintenance and suspension-reloading conditions.
Assuntos
Calcineurina/fisiologia , Fibras Musculares de Contração Lenta/fisiologia , Atrofia Muscular/fisiopatologia , Suporte de Carga/fisiologia , Animais , Inibidores de Calcineurina , Feminino , Elevação dos Membros Posteriores , Imunossupressores/farmacologia , Camundongos , Camundongos Endogâmicos ICR , Desenvolvimento Muscular/efeitos dos fármacos , Desenvolvimento Muscular/fisiologia , Fibras Musculares de Contração Rápida/efeitos dos fármacos , Fibras Musculares de Contração Rápida/fisiologia , Fibras Musculares de Contração Rápida/ultraestrutura , Fibras Musculares de Contração Lenta/efeitos dos fármacos , Fibras Musculares de Contração Lenta/ultraestrutura , Músculo Esquelético/efeitos dos fármacos , Músculo Esquelético/fisiopatologia , Músculo Esquelético/ultraestrutura , Atrofia Muscular/patologia , Cadeias Pesadas de Miosina/análise , Isoformas de Proteínas/análise , Recuperação de Função Fisiológica/fisiologia , Transdução de Sinais/efeitos dos fármacos , Tacrolimo/farmacologiaRESUMO
Skeletal muscles consist of slow-twitch and fast-twitch muscle fibers, which have distinct physiological and biochemical properties. The muscle fiber composition determines the contractile velocity and fatigability of a particular skeletal muscle. We analyzed the systemic distribution of slow muscle fibers in all rodent skeletal muscles by myosin ATPase staining and found that only seven hindlimb skeletal muscles were extremely rich in slow muscle fibers. These included the mouse piriformis (56.5%), gluteus minimus (35.7%), vastus intermedius (24.7%), quadratus femoris (69.9%), adductor brevis (44.3%), gracilis (24.6%), and soleus muscles (35.1%). In mice, the relative proportion of slow muscle fibers did not exceed 15% in skeletal muscles in other regions. The distribution of slow muscle fibers was well conserved in rats and rabbits. The soleus muscle is an important antigravity muscle in both rodents and humans; therefore, these skeletal muscles rich in slow muscle fibers might play an important role in sustaining neutral alignment of the lower extremity.
Assuntos
Membro Posterior/enzimologia , Fibras Musculares de Contração Lenta/enzimologia , Músculo Esquelético/enzimologia , Miosinas/metabolismo , Sequência de Aminoácidos , Animais , Masculino , Camundongos , Dados de Sequência Molecular , Miosinas/genética , Coelhos , RatosRESUMO
The effects of endurance training and acute exhaustive exercise on plasma levels of three superoxidedismutase (SOD) isoenzymes and the ability of superoxide generation in neutrophils were studied. Eighteen healthy male students, aged 17-22 years, who volunteered for this study, underwent three months of endurance training in swimming or running. Before and after the training course, they performed acute exercise and blood samples were collected before and after this exercise. The endurance training significantly increased maximal oxygen uptake (VO2max) in all subjects. Neither the endurance training nor the acute exercise affected the plasma CuZn-SOD level. Acute exercise after the training, but not before the training, increased both the plasma Mn-SOD and extracellular SOD (EC-SOD) levels by 33.6 and 33.5%, respectively. The training decreased the EC-SOD level at rest by 22.2%. Acute exercise after the training, but not before the training, increased the plasma lipid peroxide level, suggesting higher oxidative stress in trained subjects during exhaustive exercise. The ability of neutrophils to generate superoxide was increased by the acute exercise, but induction of the superoxide was suppressed after training. These results indicate that EC-SOD levels were changed in a different manner from the CuZn-SOD and Mn-SOD: it was decreased by training but was increased by acute exercise, suggesting that endurance training increases the reserve of EC-SOD in tissues. The results also suggest the possibility of plasma EC-SOD assay as a new index of endurance training.
Assuntos
Exercício Físico , Isoenzimas , Plasma/metabolismo , Superóxido Dismutase/sangue , Superóxido Dismutase/química , Adolescente , Adulto , Regulação Enzimológica da Expressão Gênica , Humanos , Peróxidos Lipídicos/sangue , Masculino , Neutrófilos/metabolismo , Estresse Oxidativo , Oxigênio/metabolismo , Consumo de Oxigênio , Resistência Física , Isoformas de Proteínas , Corrida , Superóxidos/metabolismo , Natação , Fatores de TempoRESUMO
The purpose of this study was to determine whether the reoxygenation rate (Reoxy-rate) immediately after static exercise at various submaximal intensities would be related to muscle oxidative capacity. Seven healthy male subjects performed isometric handgrip exercise for 10 sec at 30%, 60% and 90% of maximal voluntary contraction (MVC). The Reoxy-rate and muscle oxygen consumption during exercise (muscle VO2EX) were monitored by near infrared continuous wave spectroscopy (NIRcws). The muscle oxidative capacity was evaluated by the time constant for phosphocreatine resynthesis (PCrTc) using 31-phosphorus magnetic resonance spectroscopy (31P-MRS). The Peak blood flow of brachial artery after exercise (BABFpeak) was measured using Doppler ultrasound. There was no correlation between PCrTc and Reoxy-rate at 30% and 60% MVC. In contrast, Reoxy-rate at 90% MVC was positively correlated to PCrTC (r = 0.825, p < 0.05). The muscle VO2EX increased 5.9, 8.8 and 12.6-fold of the resting on average at 30%, 60% and 90% MVC, respectively, and the muscle VO2EX at 90% MVC was significantly higher than that at 30% and 60% MVC. On the other hand, BABFpeak increased only just 1.9, 2.4 and 2.7-fold of the resting on average at 30%, 60% and 90% MVC, respectively (Fig. 4). These results suggest that the higher oxidative capacity muscle shows slower muscle reoxygenation after 10 sec isometric exercise at 90% MVC because the Reoxy-rate after this type of exercise may be influenced more by muscle VO2 than by O2 supply. In contrast, 60% MVC and lower exercise intensities may not be severe enough to influence the muscle VO2 dependent Reoxy-rate.
Assuntos
Exercício Físico , Contração Isométrica , Músculo Esquelético/metabolismo , Oxigênio/metabolismo , Humanos , Masculino , Músculo Esquelético/irrigação sanguínea , Músculo Esquelético/diagnóstico por imagem , Músculo Esquelético/fisiologia , Oxirredução , Ultrassonografia DopplerRESUMO
BACKGROUND: In adipose cells, adipose triglyceride lipase (ATGL) catalyzes the first step in adipocyte triacylglyceride hydrolysis, thereby regulating both basal and hormone-stimulated lipolysis. However, little is known about the molecular mechanism(s) underlying habitual exercise-induced adaptive modulation of ATGL in white adipocytes via alteration in transcription regulator and lipolytic cofactors. METHODOLOGY/PRINCIPAL RESULTS: Male Wistar rats were randomly divided into 2 groups a sedentary control group (CG) and a habitual exercise group (EG). The EG was subjected to running on a treadmill set at 5 days per week for 9 weeks. The CG was not subjected to running on a treadmill. In the EG, levels of ATGL mRNA and protein were elevated with a significant increase in lipolysis compared with the CG, accompanied by a significant increase in associations of CGI-58 with ATGL protein. Under these conditions, an upregulation of peroxisome proliferation-activated receptorg-2 (PPARg-2) was observed. In the EG, the addition of rosiglitazone further significantly increased the levels of ATGL protein compared with the CG. However, attenuated levels of the ATGL protein in adipocytes were obtained by the addition of insulin, which is known to inhibit the expression of ATGL, in both types of groups. Actually, levels of plasma insulin were significantly reduced in the EG compared with the CG. CONCLUSIONS: These data suggest that elevated levels of ATGL are involved in the exercise-induced enhancement of lipolysis in primary adipocytes. The exact mechanism(s) underlying this phenomenon is associated, at least in part, with upregulated transcriptional activation of PPARg-2. In addition, exercise-induced lower circulation levels of insulin also correlate with habitual exercise-induced higher levels of ATGL in primary adipocytes.
Assuntos
Adipócitos/enzimologia , Epididimo/citologia , Lipase/metabolismo , Lipólise , Condicionamento Físico Animal , Aciltransferases , Adipócitos/efeitos dos fármacos , Animais , Peso Corporal/efeitos dos fármacos , Proteínas de Transporte/metabolismo , DNA/metabolismo , Regulação Enzimológica da Expressão Gênica/efeitos dos fármacos , Células HeLa , Humanos , Insulina/sangue , Insulina/farmacologia , Lipase/genética , Lipólise/efeitos dos fármacos , Masculino , Tamanho do Órgão/efeitos dos fármacos , PPAR gama/genética , PPAR gama/metabolismo , Perilipina-1 , Fosfoproteínas/metabolismo , Ligação Proteica/efeitos dos fármacos , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Wistar , Rosiglitazona , Esterol Esterase/metabolismo , Tiazolidinedionas/farmacologiaRESUMO
Stimulation of Toll-like receptor 4 (TLR4) by lipopolysaccharide (LPS) triggers myeloid differentiation factor 88 (MyD88)-dependent early-phase NF-kappaB activation and Toll/IL-1 receptor domain-containing adaptor-inducing IFN-beta (TRIF)-dependent late-phase NF-kappaB activation. In a previous study, we have shown that beta(2)-adrenergic receptor (beta(2)AR) functions as a negative regulator of NF-kappaB activation through beta-arrestin 2 in the macrophage cell line RAW264 and that down-regulation of beta(2)AR expression in response to LPS is essential for NF-kappaB activation and expression of its target gene, inducible nitric oxide synthase (NOS II). Here, we demonstrate that beta(2)AR plays an important role in TRIF-dependent late-phase NF-kappaB activation. LPS-stimulated down-regulation was induced in MyD88-knockdown cells, but not in TRIF-knockdown cells, suggesting that beta(2)AR expression was down-regulated by the TRIF-dependent pathway. On the other hand, depletion of beta(2)AR or beta-arrestin 2 expression by siRNA decreased cytoplasmic IkappaB alpha and abrogated late-phase IkappaB alpha degradation and NF-kappaB activation in response to LPS. Inducible nitric oxide synthase (NOS II) expression was increased continuously during 24 h of LPS stimulation in control cells, but decreased in beta(2)AR or beta-arrestin 2-knockdown cells after 6 h of LPS stimulation. These findings suggest that beta(2)AR functions not only as a negative regulator of NF-kappaB activation, but also as a stabilizing factor of the NF-kappaB/IkappaB alpha complex through cytoplasmic beta-arrestin 2, and that TRIF-dependent down-regulation of beta(2)AR expression increases the level of cytoplasmic NF-kappaB/IkappaB alpha complex free from beta-arrestin 2, leading to continuous late-phase NF-kappaB activation.
Assuntos
NF-kappa B/metabolismo , Receptores Adrenérgicos beta 2/fisiologia , Receptor 4 Toll-Like/fisiologia , Proteínas Adaptadoras de Transporte Vesicular/imunologia , Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Animais , Arrestinas/genética , Arrestinas/imunologia , Arrestinas/metabolismo , Linhagem Celular , Regulação para Baixo , Técnicas de Silenciamento de Genes , Lipopolissacarídeos/farmacologia , Macrófagos/metabolismo , Camundongos , Fator 88 de Diferenciação Mieloide/genética , Óxido Nítrico Sintase Tipo II/metabolismo , Receptores Adrenérgicos beta 2/imunologia , Transdução de Sinais , Receptor 4 Toll-Like/imunologia , beta-Arrestina 2 , beta-ArrestinasRESUMO
Exercise dramatically increases oxygen consumption and causes oxidative stress. Superoxide dismutase (SOD) is important in the first-line defence mechanisms against oxidative stress. To investigate the effect of acute exercise on the expression of SOD, we examined the expression of mRNA for three SOD isozymes, in mice run on a treadmill to exhaustion. Six hours after exercise, the expression of extracellular SOD (EC-SOD) mRNA increased significantly in skeletal muscle and persisted for 24 h, whereas no change was observed for cytoplasmic and mitochondrial SOD mRNA. Moreover, acute exercise also induced EC-SOD mRNA in the aorta. These results suggest that a single bout of exercise is enough to augment the expression EC-SOD mRNA in skeletal muscle and the aorta, and may partly explain the beneficial effect of exercise.
Assuntos
Aorta/enzimologia , Músculo Esquelético/enzimologia , Esforço Físico , Superóxido Dismutase/biossíntese , Animais , Masculino , Camundongos , Camundongos Endogâmicos C57BL , RNA Mensageiro/metabolismo , Superóxido Dismutase/genéticaRESUMO
It is not clear whether muscle oxygenation (O(2-NIRS)) measured by near-infrared spectroscopy (NIRS) correlates with femoral venous SO2 (S(fv)o2) during normoxic exercise. Therefore, the purpose of this study was to compare physiologically calibrated O(2-NIRS) with S(fv)o2 in subjects performing one-legged dynamic knee extension exercise (1L-KEE). Five healthy male subjects (age 25+/-2 year, height 177.8+/-4.8 cm, body weight 67.1 +/- 5.0 kg; mean +/- SD) performed 1L-KEE at 20, 40, and 60% of peak work rate (WR-peak) each for 4 min. S(fv)o2 was measured at rest and during the 3rd minute of each work rate. O(2-NIRS) was continuously monitored in a proximal region of the vastus lateralis (VL-p), a distal region of VL (VL-d), and a proximal region of the rectus femoris (RF-p). S(fv)o2 was 56.0% at rest and decreased to 36.6 at 20% WR-peak, 35.8 at 40% WR-peak, and 31.1 at 60% WR-peak. There was a significant correlation between O(2-NIRS) and S(fv)o2(VL-p: r (2) = 0.62, VL-d: r2 = 0.35, RF-p: r2 = 0.62, with a moderate variation among individuals at each site; residual values = 4.83 - 11.75). These data indicate that NIRS measurement provides a reflection of S(fv)o2 during 20-60% WR-peak of normoxic 1L-KEE.
Assuntos
Exercício Físico/fisiologia , Veia Femoral/fisiologia , Joelho/fisiologia , Oxigênio/sangue , Músculo Quadríceps/fisiologia , Adulto , Teste de Esforço , Humanos , Masculino , Contração Muscular , Consumo de Oxigênio , Esforço Físico/fisiologia , Espectroscopia de Luz Próxima ao InfravermelhoRESUMO
Neurotrophins are essential for the survival and differentiation of neurons in the central and peripheral nervous systems. The binding of neurotrophins to their Trk receptors induces autophosphorylation of tyrosine residues and activation of several signaling components. However, the downstream signaling cascades remain to be fully elucidated. Here we describe molecular cloning of human SH2-B alpha, PH and SH2-domain-containing adaptor protein, as a TrkB binding protein, and how SH2-B alpha associate with the cytoplasmic domain of TrkB at phosphorylated tyrosine residues in the kinase activation loop. There was no distinct inhibitory or inducing effect on kinase activity detected by either a full-length or an SH2 domain of SH2-B alpha in vitro, even though the regulation mechanism of the activation loop on tyrosine kinase activity has been described. In addition to SH2-B alpha, the expression of three SH2-B alternative splice variants, SH2-B beta, gamma and delta, was detected in human cell lines. These splicing variants have unique carboxyl-terminal amino acid sequences due to insertion sequences as well as reading frameshifts.
Assuntos
Receptor trkB/metabolismo , Tirosina/metabolismo , Domínios de Homologia de src , Sequência de Aminoácidos , Sequência de Bases , Linhagem Celular , Primers do DNA , Humanos , Dados de Sequência Molecular , Fosforilação , Receptor trkB/química , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Homologia de Sequência de Aminoácidos , Técnicas do Sistema de Duplo-HíbridoRESUMO
Effects of environmental (cold) stress and aging on cells in monocyte/macrophage lineage were investigated. We demonstrated that immune suppressive states seen in acute cold-stressed mice (8-10 weeks of age) is attributable to FcγRII(bright) suppressor macrophages. Serum corticosterone levels were markedly increased in acute cold-stressed mice. In addition, expression of glucocorticoids (GC) receptor mRNA was observed in FcγRII(bright) cells from these mice. The increase of FcγRII(bright) cells in peritoneal exudate cells caused by acute cold stress was inhibited by adrenalectomy or administration of a saturating amount of the GC antagonist RU 38486 (mifepristone). On the contrary, administration of the GC agonist, dexamethasone, markedly increased the proportion of FcγRII(bright) cells in peritoneal exudate cells of control mice. These results suggest that the generation of FcγRII(bright) suppressor cells of monocyte/macrophage lineage by acute cold stress was mediated by action of GC through the GC receptor. We likewise found that the proportion of FcγRII(bright) suppressor macrophages is increased in aged mice (22-24 months of age). Meanwhile, activated macrophages which function as antigen presenting cells were decreased in aged rats. Both the basal corticosterone concentrations in serum and the expression of mRNA for GC receptor in peritoneal macrophages increased significantly in aged animals, suggesting that these populational and functional changes of macrophages in aged animals were mediated, in part, by the increased basal levels of GC. This is probably being responsible for immunosenescence.
RESUMO
Three-week exercise training decreased the steady state level of beta(2)-adrenergic receptor (beta(2)AR) mRNA in peritoneal macrophages from BALB/c mice. When peritoneal macrophages from both exercise-trained and sedentary control mice were stimulated with lipopolysaccharide (LPS), interleukin (IL)-12 mRNA and protein expression was markedly higher in trained mice than in control mice. To determine whether enhanced production of IL-12 was associated with decreased expression of beta(2)AR, we transfected the macrophage cell line, RAW264, with a eukaryotic expression vector containing beta(2)ar cDNA, establishing a cell line overexpressing beta(2)AR (RAWar). Following LPS stimulation, IL-12 mRNA and protein expression was significantly lower in RAWar cells than in RAW264 cells transfected with vector alone (RAWvec). Furthermore, when the expression of transfected beta(2)AR in RAWar cells was down-regulated by a tetracycline repressor-regulated mammalian expression system, expression of IL-12 mRNA and protein following LPS stimulation tended to return to the levels in RAWvec cells. These findings indicate that macrophage production of IL-12 following LPS stimulation is regulated by the expression level of beta(2)AR, suggesting that the down-regulation of beta(2)AR expression associated with exercise training improves IL-12-induced type 1 helper T cell-mediated immune responses.