RESUMEN
The skeletal muscle is a pivotal organ involved in the regulation of both energy metabolism and exercise capacity. There is no doubt that exercise contributes to a healthy life through the consumption of excessive energy or the release of myokines. Skeletal muscles exhibit insulin sensitivity and can rapidly uptake blood glucose. In addition, they can undergo non-shivering thermogenesis through actions of both the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) and small peptide, sarcolipin, resulting in systemic energy metabolism. Accordingly, the maintenance of skeletal muscles is important for both metabolism and exercise. Prolyl isomerase Pin1 is an enzyme that converts the cis-trans form of proline residues and controls substrate function. We have previously reported that Pin1 plays important roles in insulin release, thermogenesis, and lipolysis. However, the roles of Pin1 in skeletal muscles remains unknown. To clarify this issue, we generated skeletal muscle-specific Pin1 knockout mice. Pin1 deficiency had no effects on muscle weights, morphology and ratio of fiber types. However, they showed exacerbated obesity or insulin resistance when fed with a high-fat diet. They also showed a lower ability to exercise than wild type mice did. We also found that Pin1 interacted with SERCA and elevated its activity, resulting in the upregulation of oxygen consumption. Overall, our study reveals that Pin1 in skeletal muscles contributes to both systemic energy metabolism and exercise capacity.
Asunto(s)
Metabolismo Energético , Músculo Esquelético , Peptidilprolil Isomerasa de Interacción con NIMA , Condicionamiento Físico Animal , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico , Animales , Masculino , Ratones , Dieta Alta en Grasa , Metabolismo Energético/genética , Resistencia a la Insulina , Ratones Endogámicos C57BL , Ratones Noqueados , Músculo Esquelético/metabolismo , Peptidilprolil Isomerasa de Interacción con NIMA/metabolismo , Peptidilprolil Isomerasa de Interacción con NIMA/genética , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/metabolismo , ATPasas Transportadoras de Calcio del Retículo Sarcoplásmico/genéticaRESUMEN
Hepatic stellate cells (HSCs) produce extracellular matrixes (ECMs), such as collagen and fibronectin, in response to stimulation with transforming growth factor ß (TGFß). The massive ECM accumulation in the liver due to HSCs causes fibrosis which eventually leads to hepatic cirrhosis and hepatoma development. However, details of the mechanisms underlying continuous HSC activation are as yet poorly understood. We thus attempted to elucidate the role of Pin1, one of the prolyl isomerases, in the underlying mechanism(s), using the human HSC line LX-2. Treatment with Pin1 siRNAs markedly alleviated the TGFß-induced expressions of ECM components such as collagen 1a1/2, smooth muscle actin and fibronectin at both the mRNA and the protein level. Pin1 inhibitors also decreased the expressions of fibrotic markers. In addition, it was revealed that Pin1 associates with Smad2/3/4, and that four Ser/Thr-Pro motifs in the linker domain of Smad3 are essential for binding with Pin1. Pin1 significantly regulated Smad-binding element transcriptional activity without affecting Smad3 phosphorylations or translocation. Importantly, both Yes-associated protein (YAP) and WW domain-containing transcription regulator (TAZ) also participate in ECM induction, and upregulate Smad3 activity rather than TEA domain transcriptional factor transcriptional activity. Although Smad3 interacts with both TAZ and YAP, Pin1 facilitates the Smad3 association with TAZ, but not that with YAP. In conclusion, Pin1 plays pivotal roles in ECM component productions in HSCs through regulation of the interaction between TAZ and Smad3, and Pin1 inhibitors may have the potential to ameliorate fibrotic diseases.
Asunto(s)
Fibronectinas , Isomerasa de Peptidilprolil , Humanos , Isomerasa de Peptidilprolil/genética , Isomerasa de Peptidilprolil/metabolismo , Fibronectinas/genética , Fibronectinas/metabolismo , Células Estrelladas Hepáticas/metabolismo , Factor de Crecimiento Transformador beta/metabolismo , Cirrosis Hepática/patología , Fibrosis , Matriz Extracelular/metabolismo , Factor de Crecimiento Transformador beta1/genética , Factor de Crecimiento Transformador beta1/metabolismo , Proteína smad3/genética , Proteína smad3/metabolismo , Peptidilprolil Isomerasa de Interacción con NIMA/genética , Peptidilprolil Isomerasa de Interacción con NIMA/metabolismoRESUMEN
A well-tuned inflammatory response is crucial for an effective immune process. Nuclear factor-kappa B (NF-κB) is a key mediator of inflammatory and innate immunity responses, and its dysregulation is closely associated with immune-related diseases. MicroRNAs (miRNAs) are important inflammation modulators. However, miRNA-regulated mechanisms that implicate NF-κB activity are not fully understood. This study aimed to identify a potential miRNA that could modulate the dysregulated NF-κB signaling during inflammation. We identified miR-582-5p that was significantly downregulated in inflamed murine adipose tissues and RAW264.7 cells. S-phase kinase-associated protein 1 (SKP1), a core component of an E3 ubiquitin ligase that regulates the NF-κB pathway, was proposed as a biological target of miR-582-5p by using TargetScan. The binding of miR-582-5p to a 3'-untranslated region site on Skp1 was confirmed using a dual-luciferase reporter assay; in addition, transfection with a miR-582-5p mimic suppressed SKP1 expression in RAW264.7 cells. Importantly, exogenous miR-582-5p attenuated the production of pro-inflammatory cytokines such as tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6 through suppressing the degradation of the NF-κB inhibitor alpha, followed by the nuclear translocation of NF-κB. Therefore, exogenously applied miR-582-5p can attenuate the NF-κB signaling pathway via targeting Skp1; this provides a prospective therapeutic strategy for treating inflammatory and immune diseases.
Asunto(s)
MicroARNs , FN-kappa B , Animales , Ratones , Inflamación/metabolismo , MicroARNs/genética , MicroARNs/metabolismo , FN-kappa B/metabolismo , Proteínas Quinasas Asociadas a Fase-S/genética , Proteínas Quinasas Asociadas a Fase-S/metabolismo , Transducción de SeñalRESUMEN
Our previous studies using rodent models have suggested an essential role for Pin1 in the pathogenesis of non-alcoholic steatohepatitis (NASH). In addition, interestingly, serum Pin1 elevation has been reported in NASH patients. However, no studies have as yet examined the Pin1 expression level in human NASH livers. To clarify this issue, we investigated the expression level and subcellular distribution of Pin1 in liver specimens obtained using needle-biopsy samples from patients with NASH and healthy liver donors. Immunostaining using anti-Pin1 antibody revealed the Pin1 expression level to be significantly higher, particularly in nuclei, in the livers of NASH patients than those of healthy donors. In the samples from patients with NASH, the amount of nuclear Pin1 was revealed to be negatively related to serum alanine aminotransferase (ALT), while tendencies to be associated with other serum parameters such as aspartate aminotransferase (AST) and platelet number were noted but did not reach statistical significance. Such unclear results and the lack of a significant relationship might well be attributable to our small number of NASH liver samples (n = 8). Moreover, in vitro, it was shown that addition of free fatty acids to medium induced lipid accumulation in human hepatoma HepG2 and Huh7 cells, accompanied with marked increases in nuclear Peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (Pin1), in accordance with the aforementioned observations in human NASH livers. In contrast, suppression of Pin1 gene expression using siRNAs attenuated the free fatty acid-induced lipid accumulation in Huh7 cells. Taken together, these observations strongly suggest that increased expression of Pin1, particularly in hepatic nuclei, contributes to the pathogenesis of NASH with lipid accumulation.
Asunto(s)
Carcinoma Hepatocelular , Hipercolesterolemia , Neoplasias Hepáticas , Enfermedad del Hígado Graso no Alcohólico , Humanos , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Peptidilprolil Isomerasa de Interacción con NIMA/genética , Peptidilprolil Isomerasa de Interacción con NIMA/metabolismo , Isomerasa de Peptidilprolil/genética , Ácidos Grasos no Esterificados , Línea CelularRESUMEN
Citrus hassaku extract reportedly activates AMPK. Because this extract contains an abundance of auraptene, we investigated whether pure auraptene activates AMPK and inhibits proliferation using prostate cancer cell lines. Indeed, auraptene inhibited the proliferation and migration of LNCaP cells and induced phosphorylation of AMPK or its downstream ACC in LNCaP, PC3, and HEK-293 cells, but not in DU145 cells not expressing LKB1. In addition, the mTOR-S6K pathway, located downstream from activated AMPK, was also markedly suppressed by auraptene treatment. Importantly, it was shown that auraptene reduced androgen receptor (AR) and prostate-specific antigen (PSA) expressions at both the protein and the mRNA level. This auraptene-induced downregulation of PSA was partially but significantly reversed by treatment with AMPK siRNA or the AMPK inhibitor compound C, suggesting AMPK activation to, at least partially, be causative. Finally, in DU145 cells lacking the LKB1 gene, exogenously induced LKB1 expression restored AMPK phosphorylation by auraptene, indicating the essential role of LKB1. In summary, auraptene is a potent AMPK activator that acts by elevating the AMP/ATP ratio, thereby potentially suppressing prostate cancer progression, via at least three molecular mechanisms, including suppression of the mTOR-S6K pathway, reduced lipid synthesis, and AR downregulation caused by AMPK activation.
Asunto(s)
Proteínas Quinasas Activadas por AMP , Neoplasias de la Próstata , Masculino , Humanos , Proteínas Quinasas Activadas por AMP/metabolismo , Fosforilación , Proteínas Serina-Treonina Quinasas/metabolismo , Antígeno Prostático Específico/genética , Antígeno Prostático Específico/metabolismo , Receptores Androgénicos/genética , Receptores Androgénicos/metabolismo , Próstata/metabolismo , Células HEK293 , Quinasas de la Proteína-Quinasa Activada por el AMP , Serina-Treonina Quinasas TOR/metabolismo , Neoplasias de la Próstata/tratamiento farmacológico , Neoplasias de la Próstata/metabolismo , Proliferación Celular , Línea Celular TumoralRESUMEN
The transcription factors hypoxia-inducible factor-1α and -2α (HIF-1α/2α) are the major regulators of the cellular response to hypoxia and play a key role in renal fibrosis associated with acute and chronic kidney disease. Jumonji domain-containing 1a (JMJD1A), a histone H3 lysine 9 (H3K9) demethylase, is reported to be an important target gene of HIF-α. However, whether JMJD1A and H3K9 methylation status play a role in renal fibrosis is unclear. Here, we investigated the involvement of HIF-α, JMJD1A, and monomethylated/dimethylated H3K9 (H3K9me1/H3K9me2) levels in unilateral ureteral obstruction (UUO)-induced renal fibrosis in mice. Intraperitoneal administration of FG4592, an inhibitor of HIF-α prolyl hydroxylase, which controls HIF-α protein stability, significantly attenuated renal fibrosis on days 3 and 7 following UUO. FG4592 concomitantly increased JMJD1A expression, decreased H3K9me1/me2 levels, reduced profibrotic gene expression, and increased erythropoietin expression in renal tissues of UUO mice. The beneficial effects of FG4592 on renal fibrosis were inhibited by the administration of JMJD1A-specific siRNA to mice immediately following UUO. Incubation of normal rat kidney-49F and/or -52E cells with transforming growth factor-ß1 (TGF-ß1) in vitro resulted in upregulated expression of α-smooth muscle actin and H3K9me1/me2, and these effects were inhibited by cotreatment with FG4592. In contrast, FG4592 treatment further enhanced the TGF-ß1-stimulated upregulation of JMJD1A but had no effect on TGF-ß1-stimulated expression of the H3K9 methyltransferase euchromatic histone-lysine N-methyltransferase 2. Collectively, these findings establish a crucial role for the HIF-α1/2-JMJD1A-H3K9me1/me2 regulatory axis in the therapeutic effect of FG4592 in renal fibrosis.NEW & NOTEWORTHY Using a mouse model of renal fibrosis and transforming growth factor-ß1-stimulated rat cell lines, we show that treatment with FG4592, an inhibitor of hypoxia-inducible factor-1α and -2α (HIF-1α/2α) prolyl hydroxylase decreases renal fibrosis and concomitantly reduces methylated lysine 9 of histone H3 (H3K9) levels via upregulation of Jumonji domain-containing 1a (JMJD1A). The results identify a novel role for the HIF-1α/2α-JMJD1A-H3K9 regulatory axis in suppressing renal fibrosis.
Asunto(s)
Eritropoyetina , Enfermedades Renales , Inhibidores de Prolil-Hidroxilasa , Obstrucción Ureteral , Ratas , Animales , Factor de Crecimiento Transformador beta1/metabolismo , Inhibidores de Prolil-Hidroxilasa/farmacología , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Histonas/metabolismo , Lisina/metabolismo , ARN Interferente Pequeño , Actinas/metabolismo , Fibrosis , Obstrucción Ureteral/complicaciones , Obstrucción Ureteral/tratamiento farmacológico , Enfermedades Renales/complicaciones , Hipoxia/metabolismo , Procolágeno-Prolina Dioxigenasa/metabolismo , N-Metiltransferasa de Histona-Lisina/metabolismo , Eritropoyetina/metabolismoRESUMEN
Carnosic acid (CA), carnosol (CL) and rosmarinic acid (RA), components of the herb rosemary, reportedly exert favorable metabolic actions. This study showed that both CA and CL, but not RA, induce significant phosphorylation of AMP-dependent kinase (AMPK) and its downstream acetyl-CoA carboxylase 1 (ACC1) in HepG2 hepatoma cells. Glucose-6-phosphatase (G6PC) and phosphoenolpyruvate carboxykinase 1 (PCK1), rate-limiting enzymes of hepatic gluconeogenesis, are upregulated by forskolin stimulation, and this upregulation was suppressed when incubated with CA or CL. Similarly, a forskolin-induced increase in CRE transcriptional activity involved in G6PC and PCK1 regulations was also stymied when incubated with CA or CL. In addition, mRNA levels of ACC1, fatty acid synthase (FAS) and sterol regulatory element-binding protein 1c (SREBP-1c) were significantly reduced when incubated with CA or CL. Finally, it was shown that CA and CL suppressed cell proliferation and reduced cell viability, possibly as a result of AMPK activation. These findings raise the possibility that CA and CL exert a protective effect against diabetes and fatty liver disease, as well as subsequent cases of hepatoma.
Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Abietanos/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Gluconeogénesis/genética , Lipogénesis/genética , Animales , Apoptosis/efectos de los fármacos , Apoptosis/genética , Proliferación Celular/efectos de los fármacos , Proliferación Celular/genética , Ácidos Grasos/biosíntesis , Gluconeogénesis/efectos de los fármacos , Células HEK293 , Células Hep G2 , Humanos , Lipogénesis/efectos de los fármacos , Ratones , Oxidación-Reducción , Fosforilación/efectos de los fármacos , Extractos Vegetales/farmacología , Rosmarinus/química , Proteína p53 Supresora de Tumor/metabolismo , Regulación hacia Arriba/efectos de los fármacos , Regulación hacia Arriba/genéticaRESUMEN
Hyperuricemia has been recognized as a risk factor for insulin resistance as well as one of the factors leading to diabetic kidney disease (DKD). Since DKD is the most common cause of end-stage renal disease, we investigated whether febuxostat, a xanthine oxidase (XO) inhibitor, exerts a protective effect against the development of DKD. We used KK-Ay mice, an established obese diabetic rodent model. Eight-week-old KK-Ay mice were provided drinking water with or without febuxostat (15 µg/mL) for 12 weeks and then subjected to experimentation. Urine albumin secretion and degrees of glomerular injury judged by microscopic observations were markedly higher in KK-Ay than in control lean mice. These elevations were significantly normalized by febuxostat treatment. On the other hand, body weights and high serum glucose concentrations and glycated albumin levels of KK-Ay mice were not affected by febuxostat treatment, despite glucose tolerance and insulin tolerance tests having revealed febuxostat significantly improved insulin sensitivity and glucose tolerance. Interestingly, the IL-1ß, IL-6, MCP-1, and ICAM-1 mRNA levels, which were increased in KK-Ay mouse kidneys as compared with normal controls, were suppressed by febuxostat administration. These data indicate a protective effect of XO inhibitors against the development of DKD, and the underlying mechanism likely involves inflammation suppression which is independent of hyperglycemia amelioration.
Asunto(s)
Antiinflamatorios/uso terapéutico , Nefropatías Diabéticas/tratamiento farmacológico , Febuxostat/uso terapéutico , Xantina Oxidasa/antagonistas & inhibidores , Animales , Peso Corporal/efectos de los fármacos , Quimiocina CCL2/metabolismo , Colágeno/metabolismo , Nefropatías Diabéticas/inmunología , Intolerancia a la Glucosa/tratamiento farmacológico , Hiperglucemia/tratamiento farmacológico , Hiperuricemia/tratamiento farmacológico , Molécula 1 de Adhesión Intercelular/metabolismo , Interleucina-1beta/metabolismo , Interleucina-6/metabolismo , Glomérulos Renales/fisiopatología , Ratones , Ratones Endogámicos C57BL , Ratones Obesos , Estrés Oxidativo/efectos de los fármacos , Fragmentos de Péptidos/metabolismo , Ácido Úrico/sangreRESUMEN
The prolyl isomerase Pin1 binds to the phosphorylated Ser/Thr-Pro motif of target proteins and enhances their cis-trans conversion. This report is the first to show that Pin1 expression in pancreatic ß cells is markedly elevated by high-fat diet feeding and in ob/ob mice. To elucidate the role of Pin1 in pancreatic ß cells, we generated ß-cell-specific Pin1 KO (ßPin1 KO) mice. These mutant mice showed exacerbation of glucose intolerance but had normal insulin sensitivity. We identified two independent factors underlying impaired insulin secretion in the ßPin1 KO mice. Pin1 enhanced pancreatic ß-cell proliferation, as indicated by a reduced ß-cell mass in ßPin1 KO mice compared with control mice. Moreover, a diet high in fat and sucrose failed to increase pancreatic ß-cell growth in the ßPin1 KO mice, an observation to which up-regulation of the cell cycle protein cyclin D appeared to contribute. The other role of Pin1 was to activate the insulin-secretory step: Pin1 KO ß cells showed impairments in glucose- and KCl-induced elevation of the intracellular Ca2+ concentration and insulin secretion. We also identified salt-inducible kinase 2 (SIK2) as a Pin1-binding protein that affected the regulation of Ca2+ influx and found Pin1 to enhance SIK2 kinase activity, resulting in a decrease in p35 protein, a negative regulator of Ca2+ influx. Taken together, our observations demonstrate critical roles of Pin1 in pancreatic ß cells and that Pin1 both promotes ß-cell proliferation and activates insulin secretion.
Asunto(s)
Inducción Enzimática , Células Secretoras de Insulina/enzimología , Insulina/metabolismo , Peptidilprolil Isomerasa de Interacción con NIMA/metabolismo , Obesidad/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Sustitución de Aminoácidos , Animales , Sitios de Unión , Señalización del Calcio , Línea Celular , Proliferación Celular , Dieta de Carga de Carbohidratos/efectos adversos , Dieta Alta en Grasa/efectos adversos , Humanos , Secreción de Insulina , Células Secretoras de Insulina/citología , Células Secretoras de Insulina/metabolismo , Ratones Noqueados , Ratones Mutantes , Ratones Transgénicos , Mutación , Peptidilprolil Isomerasa de Interacción con NIMA/antagonistas & inhibidores , Peptidilprolil Isomerasa de Interacción con NIMA/química , Peptidilprolil Isomerasa de Interacción con NIMA/genética , Obesidad/etiología , Obesidad/patología , Proteínas Serina-Treonina Quinasas/química , Proteínas Serina-Treonina Quinasas/genética , Interferencia de ARN , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismoRESUMEN
Proinflammatory cytokines activate NF-kappaB using the IkappaB kinase (IKK) complex that phosphorylates inhibitory proteins (IkappaBs) at N-terminal sites resulting in their ubiquitination and degradation in the cytoplasm. Although ultraviolet (UV) irradiation does not lead to IKK activity, it activates NF-kappaB by an unknown mechanism through IkappaBalpha degradation without N-terminal phosphorylation. Here, we describe an adaptor function of nuclear IKKbeta in UV-induced IkappaBalpha degradation. UV irradiation induces the nuclear translocation of IkappaBalpha and association with IKKbeta, which constitutively interacts with beta-TrCP through heterogeneous ribonucleoprotein-U (hnRNP-U) leading to IkappaBalpha ubiquitination and degradation. Furthermore, casein kinase 2 (CK2) and p38 associate with IKKbeta and promote IkappaBalpha degradation by phosphorylation at C-terminal sites. Thus, nuclear IKKbeta acts as an adaptor protein for IkappaBalpha degradation in UV-induced NF-kappaB activation. NF-kappaB activated by the nuclear IKKbeta adaptor protein suppresses anti-apoptotic gene expression and promotes UV-induced cell death.
Asunto(s)
Núcleo Celular/efectos de la radiación , Quinasa I-kappa B/metabolismo , Proteínas I-kappa B/metabolismo , FN-kappa B/metabolismo , Procesamiento Proteico-Postraduccional/efectos de la radiación , Rayos Ultravioleta , Transporte Activo de Núcleo Celular , Animales , Apoptosis/efectos de la radiación , Quinasa de la Caseína II/metabolismo , Línea Celular , Núcleo Celular/metabolismo , Núcleo Celular/patología , Fibroblastos/metabolismo , Fibroblastos/efectos de la radiación , Ribonucleoproteína Heterogénea-Nuclear Grupo U/metabolismo , Humanos , Quinasa I-kappa B/deficiencia , Quinasa I-kappa B/genética , Proteínas I-kappa B/deficiencia , Proteínas I-kappa B/genética , Ratones , Ratones Noqueados , Mutación , Inhibidor NF-kappaB alfa , FN-kappa B/genética , Fosforilación , Factores de Tiempo , Factor de Transcripción ReIA/genética , Factor de Transcripción ReIA/metabolismo , Transfección , Ubiquitinación , Proteínas con Repetición de beta-Transducina/genética , Proteínas con Repetición de beta-Transducina/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismoRESUMEN
Sex hormone-binding globulin (SHBG) is a serum protein released mainly by the liver, and a low serum level correlates with a risk for metabolic syndrome including diabetes, obesity, and cardiovascular events. However, the underlying molecular mechanism(s) linking SHBG and metabolic syndrome remains unknown. In this study, using adipocytes and macrophages, we focused on the in vitro effects of SHBG on inflammation as well as lipid metabolism. Incubation with 20 nM SHBG markedly suppressed lipopolysaccharide- (LPS-) induced inflammatory cytokines, such as MCP-1, TNFα, and IL-6 in adipocytes and macrophages, along with phosphorylations of JNK and ERK. Anti-inflammatory effects were also observed in 3T3-L1 adipocytes cocultured with LPS-stimulated macrophages. In addition, SHBG treatment for 18 hrs or longer significantly induced the lipid degradation of differentiated 3T3-L1 cells, with alterations in its corresponding gene and protein levels. Notably, these effects of SHBG were not altered by coaddition of large amounts of testosterone or estradiol. In conclusion, SHBG suppresses inflammation and lipid accumulation in macrophages and adipocytes, which might be among the mechanisms underlying the protective effect of SHBG, that is, its actions which reduce the incidence of metabolic syndrome.
Asunto(s)
Adipocitos/citología , Adipocitos/metabolismo , Antiinflamatorios/farmacología , Inflamación/tratamiento farmacológico , Síndrome Metabólico/metabolismo , Globulina de Unión a Hormona Sexual/farmacología , Células 3T3-L1 , Animales , Estradiol/metabolismo , Humanos , Interleucina-6/metabolismo , Metabolismo de los Lípidos , Lipólisis , Macrófagos/citología , Macrófagos/metabolismo , Ratones , Fosforilación , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
The rising prevalence of non-alcoholic fatty liver disease (NAFLD) parallels the global increase in the number of people diagnosed with obesity and metabolic syndrome. The gut-liver axis (GLA) plays an important role in the pathogenesis of NAFLD/non-alcoholic steatohepatitis (NASH). In this review, we discuss the clinical significance and underlying mechanisms of action of gut-derived secretory factors in NAFLD/NASH, focusing on recent human studies. Several studies have identified potential causal associations between gut-derived secretory factors and NAFLD/NASH, as well as the underlying mechanisms. The effects of gut-derived hormone-associated drugs, such as glucagon-like peptide-1 analog and recombinant variant of fibroblast growth factor 19, and other new treatment strategies for NAFLD/NASH have also been reported. A growing body of evidence highlights the role of GLA in the pathogenesis of NAFLD/NASH. Larger and longitudinal studies as well as translational research are expected to provide additional insights into the role of gut-derived secretory factors in the pathogenesis of NAFLD/NASH, possibly providing novel markers and therapeutic targets in patients with NAFLD/NASH.
Asunto(s)
Células Enteroendocrinas/metabolismo , Enfermedad del Hígado Graso no Alcohólico/etiología , Animales , Factores de Crecimiento de Fibroblastos/genética , Factores de Crecimiento de Fibroblastos/metabolismo , Péptidos Similares al Glucagón/genética , Péptidos Similares al Glucagón/metabolismo , Humanos , Péptidos y Proteínas de Señalización Intercelular/genética , Péptidos y Proteínas de Señalización Intercelular/metabolismo , Neurotensina/genética , Neurotensina/metabolismo , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Enfermedad del Hígado Graso no Alcohólico/terapiaRESUMEN
Recent clinical studies have demonstrated the protective effect of xanthine oxidase (XO) inhibitors against chronic kidney diseases, although the underlying molecular mechanisms remain unclear. However, to date, neither clinical nor basic research has been carried out to elucidate the efficacy of XO inhibitor administration for IgA nephropathy. We thus investigated whether febuxostat, an XO inhibitor, exerts a protective effect against the development of IgA nephropathy, using gddY mice as an IgA nephropathy rodent model. Eight-week-old gddY mice were provided drinking water with (15 µg/mL) or without febuxostat for nine weeks and then subjected to experimentation. Elevated serum creatinine and degrees of glomerular sclerosis and fibrosis, judged by microscopic observations, were significantly milder in the febuxostat-treated than in the untreated gddY mice, while body weights and serum IgA concentrations did not differ between the two groups. In addition, elevated mRNA levels of inflammatory cytokines such as TNFα, MCP-1, IL-1ß, and IL-6, collagen isoforms and chemokines in the gddY mouse kidneys were clearly normalized by the administration of febuxostat. These data suggest a protective effect of XO inhibitors against the development of IgA nephropathy, possibly via suppression of inflammation and its resultant fibrotic changes, without affecting the serum IgA concentration.
Asunto(s)
Antiinflamatorios/uso terapéutico , Progresión de la Enfermedad , Febuxostat/uso terapéutico , Glomerulonefritis por IGA/tratamiento farmacológico , Xantina Oxidasa/antagonistas & inhibidores , Animales , Antiinflamatorios/farmacología , Quimiocinas/metabolismo , Estrés del Retículo Endoplásmico/efectos de los fármacos , Febuxostat/farmacología , Femenino , Fibrosis , Regulación de la Expresión Génica/efectos de los fármacos , Glomerulonefritis por IGA/enzimología , Glomerulonefritis por IGA/patología , Mediadores de Inflamación/metabolismo , Riñón/efectos de los fármacos , Riñón/metabolismo , Riñón/patología , Ratones Endogámicos BALB C , Xantina Oxidasa/metabolismoRESUMEN
Insulin receptor substrates (IRSs) are phosphorylated by IGF-I receptor tyrosine kinase in a ligand-dependent manner. In turn, they bind to and activate effector proteins such as PI3K, leading to various cell responses including cell proliferation. We had reported that ubiquitin ligase Nedd4 induces mono-ubiquitination of IRS-2, thereby enhancing IRS-2 tyrosine phosphorylation, leading to increased IGF signaling and mitogenic activity. Here we show that ubiquitin-specific protease 15 (USP15) antagonizes the effect of Nedd4 on IRS-2. We identified USP15 as a protein that preferentially bound to IRS-2 when IRS-2 was conjugated with ubiquitin. In HEK293 cells, Nedd4 overexpression induced IRS-2 ubiquitination, which was decreased by USP15 co-expression while increased by USP15 knockdown. Nedd4 overexpression enhanced IGF-I-dependent IRS-2 tyrosine phosphorylation, and USP15 co-expression suppressed it. Conversely, USP15 knockdown increased IRS-2 tyrosine phosphorylation and downstream signaling in prostate cancer PC-3 cells. We concluded that USP15 attenuates IGF-I signaling by antagonizing Nedd4-induced IRS-2 ubiquitination.
Asunto(s)
Complejos de Clasificación Endosomal Requeridos para el Transporte/metabolismo , Proteínas Sustrato del Receptor de Insulina/metabolismo , Factor I del Crecimiento Similar a la Insulina/metabolismo , Transducción de Señal/fisiología , Ubiquitina-Proteína Ligasas/metabolismo , Proteasas Ubiquitina-Específicas/metabolismo , Ubiquitinación/fisiología , Células HEK293 , Humanos , Ubiquitina-Proteína Ligasas Nedd4 , Proteínas Ubiquitinadas/metabolismoRESUMEN
Linear ubiquitin chain assembly complex (LUBAC), composed of SHARPIN (SHANK-associated RH domain-interacting protein), HOIL-1L (longer isoform of heme-oxidized iron-regulatory protein 2 ubiquitin ligase-1), and HOIP (HOIL-1L interacting protein), forms linear ubiquitin on nuclear factor-κB (NF-κB) essential modulator (NEMO) and induces NF-κB pathway activation. SHARPIN expression and LUBAC formation were significantly reduced in the livers of mice 24 h after the injection of either carbon tetrachloride (CCl4) or acetaminophen (APAP), both of which produced the fulminant hepatitis phenotype. To elucidate its pathological significance, hepatic SHARPIN expression was suppressed in mice by injecting shRNA adenovirus via the tail vein. Seven days after this transduction, without additional inflammatory stimuli, substantial inflammation and fibrosis with enhanced hepatocyte apoptosis occurred in the livers. A similar but more severe phenotype was observed with suppression of HOIP, which is responsible for the E3 ligase activity of LUBAC. Furthermore, in good agreement with these in vivo results, transduction of Hepa1-6 hepatoma cells with SHARPIN, HOIL-1L, or HOIP shRNA adenovirus induced apoptosis of these cells in response to tumor necrosis factor-α (TNFα) stimulation. Thus, LUBAC is essential for the survival of hepatocytes, and it is likely that reduction of LUBAC is a factor promoting hepatocyte death in addition to the direct effect of drug toxicity.
Asunto(s)
Proteínas Portadoras/metabolismo , Cirrosis Hepática/metabolismo , Complejos Multiproteicos/metabolismo , Acetaminofén/efectos adversos , Animales , Apoptosis/genética , Tetracloruro de Carbono/efectos adversos , Proteínas Portadoras/genética , Línea Celular Tumoral , Modelos Animales de Enfermedad , Fibrosis , Regulación de la Expresión Génica , Técnicas de Silenciamiento del Gen , Hepatocitos/metabolismo , Inflamación/genética , Inflamación/metabolismo , Inflamación/patología , Péptidos y Proteínas de Señalización Intracelular , Cirrosis Hepática/inducido químicamente , Cirrosis Hepática/genética , Cirrosis Hepática/patología , Masculino , Ratones , Unión Proteica , Factor de Necrosis Tumoral alfa/metabolismo , Ubiquitina-Proteína Ligasas/metabolismoRESUMEN
Recent clinical studies have revealed the treatment of diabetic patients with sodium glucose co-transporter2 (SGLT2) inhibitors to reduce the incidence of cardiovascular events. Using nicotinamide and streptozotocin (NA/STZ) -treated ApoE KO mice, we investigated the effects of short-term (seven days) treatment with the SGLT2 inhibitor luseogliflozin on mRNA levels related to atherosclerosis in the aorta, as well as examining the long-term (six months) effects on atherosclerosis development. Eight-week-old ApoE KO mice were treated with NA/STZ to induce diabetes mellitus, and then divided into two groups, either untreated, or treated with luseogliflozin. Seven days after the initiation of luseogliflozin administration, atherosclerosis-related mRNA levels in the aorta were compared among four groups; i.e., wild type C57/BL6J, native ApoE KO, and NA/STZ-treated ApoE KO mice, with or without luseogliflozin. Short-term luseogliflozin treatment normalized the expression of inflammation-related genes such as F4/80, TNFα, IL-1ß, IL-6, ICAM-1, PECAM-1, MMP2 and MMP9 in the NA/STZ-treated ApoE KO mice, which showed marked elevations as compared with untreated ApoE KO mice. In contrast, lipid metabolism-related genes were generally unaffected by luseogliflozin treatment. Furthermore, after six-month treatment with luseogliflozin, in contrast to the severe and widely distributed atherosclerotic changes in the aortas of NA/STZ-treated ApoE KO mice, luseogliflozin treatment markedly attenuated the progression of atherosclerosis, without affecting serum lipid parameters such as high density lipoprotein, low density lipoprotein and triglyceride levels. Given that luseogliflozin normalized the aortic mRNA levels of inflammation-related, but not lipid-related, genes soon after the initiation of treatment, it is not unreasonable to speculate that the anti-atherosclerotic effect of this SGLT2 inhibitor emerges rapidly, possibly via the prevention of inflammation rather than of hyperlipidemia.
Asunto(s)
Aorta/metabolismo , Apolipoproteínas E/metabolismo , Aterosclerosis/tratamiento farmacológico , Diabetes Mellitus Experimental/genética , Inflamación/genética , Metabolismo de los Lípidos/genética , Inhibidores del Cotransportador de Sodio-Glucosa 2 , Sorbitol/análogos & derivados , Animales , Aterosclerosis/complicaciones , Aterosclerosis/genética , Moléculas de Adhesión Celular/metabolismo , Citocinas/metabolismo , Diabetes Mellitus Experimental/complicaciones , Diabetes Mellitus Experimental/tratamiento farmacológico , Regulación de la Expresión Génica/efectos de los fármacos , Hiperglucemia/complicaciones , Hiperglucemia/tratamiento farmacológico , Hiperlipidemias/complicaciones , Hiperlipidemias/tratamiento farmacológico , Inflamación/complicaciones , Metabolismo de los Lípidos/efectos de los fármacos , Peroxidación de Lípido/efectos de los fármacos , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Metaloproteinasas de la Matriz/metabolismo , Ratones Endogámicos C57BL , Ratones Noqueados , Niacinamida , ARN Mensajero/genética , ARN Mensajero/metabolismo , Transportador 2 de Sodio-Glucosa/metabolismo , Sorbitol/farmacología , Sorbitol/uso terapéutico , Estreptozocina , Regulación hacia Arriba/efectos de los fármacosRESUMEN
AMP-activated protein kinase (AMPK) plays a critical role in metabolic regulation. In this study, first, it was revealed that Pin1 associates with any isoform of γ, but not with either the α or the ß subunit, of AMPK. The association between Pin1 and the AMPK γ1 subunit is mediated by the WW domain of Pin1 and the Thr(211)-Pro-containing motif located in the CBS domain of the γ1 subunit. Importantly, overexpression of Pin1 suppressed AMPK phosphorylation in response to either 2-deoxyglucose or biguanide stimulation, whereas Pin1 knockdown by siRNAs or treatment with Pin1 inhibitors enhanced it. The experiments using recombinant Pin1, AMPK, LKB1, and PP2C proteins revealed that the protective effect of AMP against PP2C-induced AMPKα subunit dephosphorylation was markedly suppressed by the addition of Pin1. In good agreement with the in vitro data, the level of AMPK phosphorylation as well as the expressions of mitochondria-related genes, such as PGC-1α, which are known to be positively regulated by AMPK, were markedly higher with reduced triglyceride accumulation in the muscles of Pin1 KO mice as compared with controls. These findings suggest that Pin1 plays an important role in the pathogenic mechanisms underlying impaired glucose and lipid metabolism, functioning as a negative regulator of AMPK.
Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Isomerasa de Peptidilprolil/metabolismo , Proteína Fosfatasa 2/metabolismo , Animales , Regulación de la Expresión Génica , Regulación Enzimológica de la Expresión Génica , Silenciador del Gen , Glucosa/química , Células HEK293 , Células Hep G2 , Humanos , Metabolismo de los Lípidos , Síndrome Metabólico/metabolismo , Metformina/química , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Ratones Transgénicos , Músculos/patología , Peptidilprolil Isomerasa de Interacción con NIMA , Fosforilación , ARN Interferente Pequeño/metabolismo , Proteínas Recombinantes/metabolismoRESUMEN
Interleukin-17A (IL-17A) is known to induce inflammatory responses and to be involved in the pathogenesis of not only autoimmune diseases, but also several metabolic and infectious diseases. In this study, IL-17A is shown to induce IL-6 expression in 3T3-L1 mature adipocytes. Interestingly, we found that IL-17A synergistically amplified TNFα-induced secretion of IL-6 and upregulation of IL-17RA expression in 3T3-L1 adipocytes. Its synergistic effects on IL-6 production were inhibited by pre-treatment with inhibitors of IκBα and JNK. Furthermore, IL-17A cooperatively enhanced LPS-mediated IL-6 production in 3T3-L1 adipocytes co-cultured with RAW264.7 macrophages. In addition, IL-17A also enhanced CCL20 production in 3T3-L1 adipocytes stimulated with TNFα or co-cultured with LPS-stimulated RAW macrophages. In high-fat diet-fed mouse epididymal adipose tissues, IL-17RA and RORγt mRNA levels were significantly increased and the serum level of CCL20 was also upregulated. Taken together, these data show that, in adipose tissues, IL-17A contributes to exacerbating insulin resistance-enhancing IL-6 production and promotes the infiltration of Th17 cells in cooperation with TNFα; these findings represent a novel hypothesis for the association between IL-17A-producing cells and type 2 diabetes.
Asunto(s)
Adipocitos/inmunología , Quimiocina CCL20/inmunología , Interleucina-17/inmunología , Interleucina-6/inmunología , Macrófagos/inmunología , Factor de Necrosis Tumoral alfa/inmunología , Células 3T3-L1 , Adipocitos/efectos de los fármacos , Animales , Interleucina-17/administración & dosificación , Macrófagos/efectos de los fármacos , Masculino , Ratones , Ratones Endogámicos C57BL , Regulación hacia ArribaRESUMEN
Uric acid (UA) is the end product of purine metabolism and can reportedly act as an antioxidant. However, recently, numerous clinical and basic research approaches have revealed close associations of hyperuricemia with several disorders, particularly those comprising the metabolic syndrome. In this review, we first outline the two molecular mechanisms underlying inflammation occurrence in relation to UA metabolism; one is inflammasome activation by UA crystallization and the other involves superoxide free radicals generated by xanthine oxidase (XO). Importantly, recent studies have demonstrated the therapeutic or preventive effects of XO inhibitors against atherosclerosis and nonalcoholic steatohepatitis, which were not previously considered to be related, at least not directly, to hyperuricemia. Such beneficial effects of XO inhibitors have been reported for other organs including the kidneys and the heart. Thus, a major portion of this review focuses on the relationships between UA metabolism and the development of atherosclerosis, nonalcoholic steatohepatitis, and related disorders. Although further studies are necessary, XO inhibitors are a potentially novel strategy for reducing the risk of many forms of organ failure characteristic of the metabolic syndrome.
Asunto(s)
Aterosclerosis/metabolismo , Síndrome Metabólico/metabolismo , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Ácido Úrico/metabolismo , Animales , Progresión de la Enfermedad , Radicales Libres/metabolismo , Insuficiencia Cardíaca/metabolismo , Humanos , Inflamasomas , Inflamación , Ratones , Superóxidos/metabolismo , Xantina Oxidasa/metabolismoRESUMEN
Prolyl isomerases are divided into three groups, the FKBP family, Cyclophilin and the Parvulin family (Pin1 and Par14). Among these isomerases, Pin1 is a unique prolyl isomerase binding to the motif including pSer/pThr-Pro that is phosphorylated by kinases. Once bound, Pin1 modulates the enzymatic activity, protein stability or subcellular localization of target proteins by changing the cis- and trans-formations of proline. Several studies have examined the roles of Pin1 in the pathogenesis of cancers and Alzheimer's disease. On the other hand, recent studies have newly demonstrated Pin1 to be involved in regulating glucose and lipid metabolism. Interestingly, while Pin1 expression is markedly increased by high-fat diet feeding, Pin1 KO mice are resistant to diet-induced obesity, non-alcoholic steatohepatitis and diabetic vascular dysfunction. These phenomena result from the binding of Pin1 to several key factors regulating metabolic functions, which include insulin receptor substrate-1, AMPK, Crtc2 and NF-κB p65. In this review, we focus on recent advances in elucidating the physiological roles of Pin1 as well as the pathogenesis of disorders involving this isomerase, from the viewpoint of the relationships between signal transductions and metabolic functions.