RESUMEN
Hepatocellular carcinoma is an end-stage complication of non-alcoholic fatty liver disease (NAFLD). Inflammation plays a critical role in the progression of non-alcoholic fatty liver disease and the development of hepatocellular carcinoma. However, whether steatosis per se promotes liver cancer, and the molecular mechanisms that control the progression in this disease spectrum remain largely elusive. The Janus kinase signal transducers and activators of transcription (JAK-STAT) pathway mediates signal transduction by numerous cytokines that regulate inflammation and may contribute to hepatocarcinogenesis. Mice with hepatocyte-specific deletion of JAK2 (L-JAK2 KO) develop extensive fatty liver spontaneously. We show here that this simple steatosis was insufficient to drive carcinogenesis. In fact, L-JAK2 KO mice were markedly protected from chemically induced tumor formation. Using the methionine choline-deficient dietary model to induce steatohepatitis, we found that steatohepatitis development was completely arrested in L-JAK2 KO mice despite the presence of steatosis, suggesting that JAK2 is the critical factor required for inflammatory progression in the liver. In line with this, L-JAK2 KO mice exhibited attenuated inflammation after chemical carcinogen challenge. This was associated with increased hepatocyte apoptosis without elevated compensatory proliferation, thus thwarting expansion of transformed hepatocytes. Taken together, our findings identify an indispensable role of JAK2 in hepatocarcinogenesis through regulating critical inflammatory pathways. Targeting the JAK-STAT pathway may provide a novel therapeutic option for the treatment of hepatocellular carcinoma.
Asunto(s)
Carcinoma Hepatocelular/metabolismo , Janus Quinasa 2/genética , Janus Quinasa 2/metabolismo , Neoplasias Hepáticas/metabolismo , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Animales , Proliferación Celular , Hígado Graso/metabolismo , Eliminación de Gen , Hepatocitos/metabolismo , Inflamación , Hígado/metabolismo , Masculino , Ratones , Ratones Noqueados , Especies Reactivas de Oxígeno/metabolismo , Transducción de SeñalRESUMEN
AIMS/HYPOTHESIS: The growing obesity epidemic necessitates a better understanding of adipocyte biology and its role in metabolism. The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway mediates signalling by numerous cytokines and hormones that regulate adipocyte function, illustrating the physiological importance of adipose JAK-STAT. The aim of this study was to investigate potential roles of adipocyte JAK2, an essential player in the JAK-STAT pathway, in adipocyte biology and metabolism. METHODS: We generated adipocyte-specific Jak2 knockout (A-Jak2 KO) mice using the Cre-loxP system with Cre expression driven by the Ap2 (also known as Fabp4) promoter. RESULTS: Starting at 2-3 months of age, male and female A-Jak2 KO mice gradually gained more body weight than control littermates primarily due to increased adiposity. This was associated with reduced energy expenditure in A-Jak2 KO mice. In perigonadal adipose tissue, the expression of numerous genes involved in lipid metabolism was differentially regulated. In addition, adipose tissue from A-Jak2 KO mice displayed impaired lipolysis in response to isoprenaline, growth hormone and leptin stimulation, suggesting that adipose JAK2 directly modulates the lipolytic program. Impaired lipid homeostasis was also associated with disrupted adipokine secretion. Accordingly, while glucose metabolism was normal at 2 months of age, by 5-6 months of age, A-Jak2 KO mice had whole-body insulin resistance. CONCLUSIONS/INTERPRETATION: Our results suggest that adipocyte JAK2 plays a critical role in the regulation of adipocyte biology and whole-body metabolism. Targeting of the JAK-STAT pathway could be a novel therapeutic option for the treatment of obesity and type 2 diabetes.
Asunto(s)
Adipocitos/metabolismo , Envejecimiento , Resistencia a la Insulina , Janus Quinasa 2/metabolismo , Lipólisis , Adipocitos/citología , Adipoquinas , Adiposidad , Animales , Composición Corporal , Peso Corporal , Citocinas/metabolismo , Femenino , Prueba de Tolerancia a la Glucosa , Masculino , Ratones , Ratones Noqueados , Obesidad , Regiones Promotoras GenéticasRESUMEN
Non-alcoholic fatty liver disease (NAFLD) is becoming the leading cause of chronic liver disease and is now considered to be the hepatic manifestation of the metabolic syndrome. However, the role of steatosis per se and the precise factors required in the progression to steatohepatitis or insulin resistance remain elusive. The JAK-STAT pathway is critical in mediating signaling of a wide variety of cytokines and growth factors. Mice with hepatocyte-specific deletion of Janus kinase 2 (L-JAK2 KO mice) develop spontaneous steatosis as early as 2 weeks of age. In this study, we investigated the metabolic consequences of jak2 deletion in response to diet-induced metabolic stress. To our surprise, despite the profound hepatosteatosis, deletion of hepatic jak2 did not sensitize the liver to accelerated inflammatory injury on a prolonged high fat diet (HFD). This was accompanied by complete protection against HFD-induced whole-body insulin resistance and glucose intolerance. Improved glucose-stimulated insulin secretion and an increase in ß-cell mass were also present in these mice. Moreover, L-JAK2 KO mice had progressively reduced adiposity in association with blunted hepatic growth hormone signaling. These mice also exhibited increased resting energy expenditure on both chow and high fat diet. In conclusion, our findings indicate a key role of hepatic JAK2 in metabolism such that its absence completely arrests steatohepatitis development and confers protection against diet-induced systemic insulin resistance and glucose intolerance.
Asunto(s)
Grasas de la Dieta/efectos adversos , Hígado Graso/enzimología , Intolerancia a la Glucosa/enzimología , Hepatocitos/enzimología , Janus Quinasa 2/metabolismo , Adiposidad/efectos de los fármacos , Adiposidad/genética , Animales , Grasas de la Dieta/farmacología , Hígado Graso/inducido químicamente , Hígado Graso/genética , Hígado Graso/patología , Eliminación de Gen , Intolerancia a la Glucosa/inducido químicamente , Intolerancia a la Glucosa/genética , Intolerancia a la Glucosa/patología , Hepatocitos/patología , Resistencia a la Insulina/genética , Janus Quinasa 2/genética , Ratones , Ratones NoqueadosRESUMEN
Fibroblast growth factor 16 (FGF-16) expression has previously been detected in mouse heart at mid-gestation in the endocardium and epicardium, suggesting a role in embryonic heart development. More specifically, exogenously applied FGF-16 has been shown to stimulate growth of embryonic myocardial cells in tissue explants. We have generated mice lacking FGF-16 by targeting the Fgf16 locus on the X chromosome. Elimination of Fgf16 expression resulted in embryonic death as early as day 11.5 (E11.5). External abnormalities, including hemorrhage in the heart and ventral body region as well as facial defects, began to appear in null embryos from E11.5. Morphological analysis of FGF-16 null hearts revealed cardiac defects including chamber dilation, thinning of the atrial and ventricular walls, and poor trabeculation, which were visible at E10.5 and more pronounced at E11.5. These findings indicate FGF-16 is required for embryonic heart development in mid-gestation through its positive effect on myocardial growth.
Asunto(s)
Factores de Crecimiento de Fibroblastos/genética , Cardiopatías Congénitas/genética , Corazón/embriología , Animales , Anomalías Craneofaciales/genética , Pérdida del Embrión/genética , Femenino , Marcación de Gen , Cardiopatías Congénitas/patología , Ratones , Ratones Noqueados , Embarazo , Segundo Trimestre del Embarazo , Cromosoma X/genéticaRESUMEN
BACKGROUND: The cardiac contractile function of hypertensive patients is higher than non-hypertensive patients so that it is beneficial for lowering cardiac contractile function of hypertensive patients. It remains unclear if MN9202, a dihydropyridine calcium channel blocker, has effects on positive inotropic responses induced by tetraethylammonium chloride (TEA), an antagonist of calcium-activated potassium channels, forskolin (FSK), an activator of adenylyl cyclase, isoproterenol (Iso), an activator of beta-adrenergic receptors, and methylene blue (MB), an inhibitor of guanylyl cyclase, in electrically stimulated rat cardiomyocytes. Myocyte shortening and intracellular calcium transients were assessed and the underlying mechanisms were investigated. METHODS: Twitch amplitude was measured by a video edge tracker method. Cell shortening/relengthening indexes including peak height (ph), peak height/baseline percent (ph/bl%), maximal velocity of shortening (+dL/dt), and maximal velocity of relengthening (-dL/dt) were recorded and analyzed by computer. Calcium transient amplitude (DeltaFFI) indicates intracellular calcium transients. RESULTS: Iso, FSK, TEA, and MB enhanced electrical stimulation induced contraction as evidenced by increased ph, ph/bl%, +/- dL/dt, and calcium transient amplitude (DeltaFFI) compared with those in the control group. Under basal conditions, MN9202 decreased electrically induced contraction (ph, ph/bl%,+dL/dt,-dL/dt) in a concentration-dependent manner from 3 x 10(-10) to 3 x 10(-6) mol/L. MN9202 significantly decreased calcium transient amplitude. Moreover, MN9202 (3 x 10(-6) mol/L) partially but significantly blocked the positive inotropic effect induced by Iso, FSK, MB, and TEA through blocking DeltaFFI. CONCLUSIONS: Iso, FSK, TEA, and MB increased the shortening and relengthening function of cardiomyocytes, which were partially blocked by MN9202. These results suggest that MN9202 may not only block the dihydropyridine receptor but may also inhibit other calcium influx. The exact mechanism of the action of MN9202 requires further study.
Asunto(s)
Dihidropiridinas/farmacología , Contracción Muscular/efectos de los fármacos , Relajación Muscular/efectos de los fármacos , Miocitos Cardíacos/efectos de los fármacos , Nitrobencenos/farmacología , Animales , Calcio/metabolismo , Forma de la Célula/efectos de los fármacos , Colforsina/farmacología , Azul de Metileno , Miocitos Cardíacos/citología , Miocitos Cardíacos/metabolismo , Ratas , Tetraetilamonio/farmacologíaRESUMEN
AIM: To investigate the relaxation effect and underlying mechanism of U50,488H (a selective kappa-opioid receptor agonist) in pulmonary artery in the rat. METHODS: Isolated pulmonary artery ring was perfused and the tension of the vessel was measured. RESULTS: U50,488H relaxed the pulmonary artery ring in a dose-dependent manner and the effect was abolished by nor-binaltorphimine, a selective kappa-opioid receptor antagonist. The relaxation effect of U50,488H in pulmonary artery was partially endothelium-dependent and was significantly attenuated in the presence of L-NAME. The relaxation effect of U50,488H was significantly attenuated by K(V) channel blocker 4-AP (4-aminopyridine), but not by glibenclamide (ATP-sensitive K+ channel blocker) nor TEA (tetraethylamonium, Ca2+-activated K+ channel blocker). Further study also showed that endothelium denudation and 4-AP have an additive inhibitory effect on pulmonary artery relaxation caused by U50,488H. CONCLUSION: Kappa-opioid receptor activation by U50,488H relaxes pulmonary artery via two separate pathways: one is endothelium-derived nitric oxide, the other is K(V) channel in pulmonary artery smooth muscle.
Asunto(s)
3,4-Dicloro-N-metil-N-(2-(1-pirrolidinil)-ciclohexil)-bencenacetamida, (trans)-Isómero/farmacología , Antihipertensivos/farmacología , Músculo Liso Vascular/efectos de los fármacos , Arteria Pulmonar/efectos de los fármacos , Antagonistas Adrenérgicos beta/farmacología , Animales , Antiinflamatorios no Esteroideos/farmacología , Atropina/farmacología , Dinorfinas/farmacología , Endotelio Vascular/efectos de los fármacos , Inhibidores Enzimáticos/farmacología , Técnicas In Vitro , Indometacina/farmacología , Masculino , Relajación Muscular/efectos de los fármacos , NG-Nitroarginina Metil Éster/farmacología , Óxido Nítrico/fisiología , Óxido Nítrico Sintasa de Tipo III/antagonistas & inhibidores , Fragmentos de Péptidos/farmacología , Bloqueadores de los Canales de Potasio/farmacología , Canales de Potasio/fisiología , Propranolol/farmacología , Ratas , Ratas Sprague-Dawley , Receptores Opioides kappa/agonistasRESUMEN
The aim of the present research is to investigate the effects of vasonatrin peptide (VNP) on hypoxia-induced proliferation and collagen synthesis in pulmonary artery smooth muscle cells (PASMCs). Smooth muscle cells isolated from rat pulmonary artery were cultured and used at passages 3-5. Cell proliferation and collagen synthesis were evaluated by cell counts, [(3)H] thymidine and [(3)H] proline incorporation. The results showed that cells exposed to hypoxia for 24 h exhibited a significant increase in [(3)H] thymidine (93%) and [(3)H] proline (52%) incorporation followed by a significant increase in cell number (47%) at 48 h in comparison with the respective normoxic controls. VNP reduced hypoxia-stimulated increase in cell proliferation in a concentration-dependent manner from 10(-8) to 10(-6) mol/L and attenuated hypoxia-induced collagen synthesis ranging from 10(-6) to 10(-5) mol/L, which is similar to but more potent than both ANP and CNP. The action of VNP on PASMCs was mimicked by 8-bromo-cGMP (10(-4) mol/L, the membrane-permeable cGMP analog), and blocked by HS-142-1 (2 x 10(-5) mol/L), the particulate guanylyl cyclase-coupled natriuretic peptide receptor antagonist, or KT-5823 (10(-6) mol/L), the cGMP-dependent protein kinase (PKG) inhibitor. The results suggest that VNP inhibits hypoxia-stimulated proliferation and collagen synthesis in cultured rat PASMCs via particulate guanylyl cyclase-coupled receptors through cGMP/PKG dependent mechanisms.
Asunto(s)
Factor Natriurético Atrial/farmacología , Colágeno/biosíntesis , GMP Cíclico/análogos & derivados , Músculo Liso Vascular/efectos de los fármacos , Arteria Pulmonar/metabolismo , Animales , Hipoxia de la Célula , Proliferación Celular/efectos de los fármacos , Células Cultivadas , GMP Cíclico/farmacología , Proteínas Quinasas Dependientes de GMP Cíclico/antagonistas & inhibidores , Proteínas Quinasas Dependientes de GMP Cíclico/fisiología , Masculino , Músculo Liso Vascular/citología , Músculo Liso Vascular/metabolismo , Miocitos del Músculo Liso/efectos de los fármacos , Miocitos del Músculo Liso/metabolismo , Arteria Pulmonar/citología , Ratas , Ratas Sprague-DawleyRESUMEN
Reactive oxygen species (ROS) have been linked to a wide variety of pathologies, including obesity and diabetes, but ROS also act as endogenous signalling molecules, regulating numerous biological processes. DJ-1 is one of the most evolutionarily conserved proteins across species, and mutations in DJ-1 have been linked to some cases of Parkinson's disease. Here we show that DJ-1 maintains cellular metabolic homeostasis via modulating ROS levels in murine skeletal muscles, revealing a role of DJ-1 in maintaining efficient fuel utilization. We demonstrate that, in the absence of DJ-1, ROS uncouple mitochondrial respiration and activate AMP-activated protein kinase, which triggers Warburg-like metabolic reprogramming in muscle cells. Accordingly, DJ-1 knockout mice exhibit higher energy expenditure and are protected from obesity, insulin resistance and diabetes in the setting of fuel surplus. Our data suggest that promoting mitochondrial uncoupling may be a potential strategy for the treatment of obesity-associated metabolic disorders.
Asunto(s)
Metabolismo Energético/genética , Mitocondrias/metabolismo , Músculo Esquelético/metabolismo , Mioblastos Esqueléticos/metabolismo , Proteínas Oncogénicas/genética , Peroxirredoxinas/genética , Especies Reactivas de Oxígeno/metabolismo , Proteínas Quinasas Activadas por AMP/metabolismo , Tejido Adiposo/metabolismo , Tejido Adiposo/patología , Animales , Línea Celular , Supervivencia Celular , Diabetes Mellitus/genética , Dieta Alta en Grasa , Glucosa/metabolismo , Glucólisis/genética , Homeostasis/genética , Immunoblotting , Resistencia a la Insulina/genética , Ratones , Ratones Noqueados , Fibras Musculares Esqueléticas/metabolismo , Obesidad/genética , Estrés Oxidativo , Consumo de Oxígeno , Proteína Desglicasa DJ-1RESUMEN
The present work was to investigate the effects of vasonatrin peptide (VNP) on cardiomyocyte protein synthesis induced by moderate hypoxia. In cultured neonatal rat cardiomyocytes, MTT methods, total protein measurement and (3)H-leucine incorporation were used to calculate the cell number and measure the protein synthesis of cardiomyocytes. Furthermore, radioimmunoassay was undertaken to observe the effects of VNP on the intracellular levels of cAMP, cGMP and the concentration of endothelin (ET) in the culture medium. The results showed that both the cell number and protein synthesis decreased with severe hypoxia for 24 h. In contrast, under moderate hypoxia, cardiomyocyte hypertrophy developed; the protein synthesis as evidenced by total protein content and 3H-eucine incorporation increased significantly. VNP reduced cardiomyocyte protein synthesis induced by moderate hypoxia in a dose-dependent manner. Furthermore, VNP increased the intracellular level of cGMP and decreased the concentration of ET in the culture medium under moderate hypoxia, but had no effect on the level of cAMP. These results suggest that VNP inhibits moderate hypoxia-induced protein synthesis in cultured neonatal rat cardiac myocytes. This effect is mediated, at least in part, by an increase in intracellular cGMP, a reduction in synthesis, and/or a release in ET of cardiomyocytes.
Asunto(s)
Factor Natriurético Atrial/farmacología , Miocitos Cardíacos/metabolismo , Biosíntesis de Proteínas , Animales , Animales Recién Nacidos , Hipoxia de la Célula , Células Cultivadas , AMP Cíclico/metabolismo , GMP Cíclico/metabolismo , Relación Dosis-Respuesta a Droga , Endotelinas/biosíntesis , Ratas , Ratas Sprague-DawleyRESUMEN
The purpose of this study was to investigate the effects of vasonatrin peptide (VNP) on electrically-induced intracellular calcium ([Ca(2+)](i)) transient and mechanism of the effects in the cardiac myocytes. The [Ca(2+)](i) transient was measured with a fluoremetric method. The effects of HS-142-1, 8-Br-cGMP and methylene blue (MB) on [Ca(2+)](i) transient in cardiac myocytes were also determined. Isoproterenol (Iso) at 10(-10)~10(-6) mol/L augmented electrically-induced [Ca(2+)](i) transient dose-dependently, which was (13+/-8)% (P>0.05), (26+/-13)% (P< 0.05), (66+/-10)% (P<0.01), (150+/-10)% (P<0.01) and (300+/-25)% (P<0.01), respectively. These effects were blocked by an beta-adrenergic bloker propranolol (10(-6) mol/L). The effect of Iso (10(-8) mol/L) on [Ca(2+)](i) transient was attenuated in a dose-dependent manner by VNP at 10(-10)~10(-6) mol/L, which was (99+/-3)% (P>0.05), (96+/-2)% (P<0.05), (84+/-6)% (P<0.01), (66+/-3)% (P<0.01) and (62+/-3)% (P<0.01), respectively. 8-Br-cGMP (10(-7)~10(-3) mol/L) aslo attenuated 10(-8) mol/L Iso-induced [Ca(2+)](i) transient dose-dependent. The effect of VNP on [Ca(2+)](i) transient was almost abolished in the presence of HS-142-1 (2x10(-5) mol/L), an antagonist of the natriuretic peptide guanylate cyclase (GC) receptors. MB (10(-5) mol/L), an inhibitor of GC, not only blocked the effect of VNP in myocytes, but also augmented electrically-induced [Ca(2+)](i) transient. VNP and HS-142-1 themselves did not change the [Ca(2+)](i) transient in the cardiac myocytes significantly. But MB augmented the [Ca(2+)](i) transient in the cardiac myocytes significantly. These results suggest that VNP attenuates [Ca(2+)](i) transient induced by Iso. This effect is possibly achieved by binding VNP with the natriuretic peptide GC receptors in the myocytes, leading to an increase in intracellular cGMP.
Asunto(s)
Factor Natriurético Atrial/farmacología , Calcio/metabolismo , Guanilato Ciclasa/metabolismo , Isoproterenol/farmacología , Receptores del Factor Natriurético Atrial/metabolismo , Animales , Canales de Calcio/metabolismo , GMP Cíclico/metabolismo , Depresión Química , Femenino , Masculino , Miocitos Cardíacos/metabolismo , RatasRESUMEN
The immunological parameters were analyzed during pregnancy of Lewis rats by the methods of flow cytometry, thymidine incorporation and enzyme-linked immunospot (ELISPOT). MHC II of spleen mononuclear cells (MNCs) and CD11c of periphery blood MNCs was apparently downregulated in late pregnancy, while the costimulatory molecules B7-1 and B7-2 showed no difference. Increased expression of Th2 cytokines (IL-10, IL-4) and TGFbeta was detected in the spleen and peripheral blood MNCs in the third trimester by flow cytometry. No suppression of Th1 cytokine represented by IFNgamma was found. Furthermore, antigen specific proliferation of spleen and peripheral blood MNCs was unchanged, but higher proliferation of MNCs from mesenteric lymph nodes was shown in late pregnancy. There was an inhibition of antigen specific antibody production in pregnancy examined by ELISPOT. These data indicate the immunomodulatory effects of sex-hormones in pregnancy, which may be related to the remission of T cell-mediated autoimmune diseases during pregnancy.
Asunto(s)
Antígeno CD11c/inmunología , Preñez/inmunología , Células Th2/inmunología , Animales , Antígeno B7-1/inmunología , Femenino , Interleucina-10/metabolismo , Interleucina-4/metabolismo , Leucocitos Mononucleares/inmunología , Complejo Mayor de Histocompatibilidad/inmunología , Embarazo , Ratas , Ratas Endogámicas Lew , Bazo/citología , Bazo/inmunología , Factor de Crecimiento Transformador beta/metabolismoRESUMEN
The purpose of this study was to investigate the vasorelaxing effect of vasonatrin peptide (VNP) on human intramammary artery (HIMA).The vasorelaxing effect of VNP on HIMA was measured by means of perfusion in vitro. The effects of HS-142-1, TEA, 8-Br-cGMP and methylene blue (MB) were also observed. It was found that VNP caused a concentration-dependent relaxation in HIMA which was independent of the endothelium. 8-Br-cGMP (0.1-1000 micromol/L) also caused a concentration-dependent relaxation in HIMA. The vasorelaxing effect of VNP disappeared in the presence of HS-142-1 (20 micromol/L), an antagonist of the natriuretic peptide guanylate cyclase (GC) receptor. MB (10 micromol/L), an inhibitor of GC, not only blocked completely the relaxation of HIMA, but also enhanced the vascular contraction induced by norepinephrine. TEA (1 mmol/L), an antagonist of calcium activated potassium channels (K(Ca)), reduced but not completely blocked the vasorelaxing effect of VNP. These findings suggest that VNP can relax HIMA, which is independent of the endothelium. This effect is possibly achieved by the binding of VNP with the natriuretic peptide GC receptors in the smooth muscle cells (SMCs), leading to an increase in intracellular cGMP level. Moreover, the vasorelaxing effect of VNP is associated with K(Ca).
Asunto(s)
Factor Natriurético Atrial/farmacología , Arterias Mamarias/fisiología , Vasodilatación/fisiología , Anciano , Relación Dosis-Respuesta a Droga , Humanos , Técnicas In Vitro , Arterias Mamarias/efectos de los fármacos , Persona de Mediana Edad , Canales de Potasio Calcio-Activados/metabolismo , Receptores Acoplados a la Guanilato-Ciclasa/metabolismo , Vasodilatación/efectos de los fármacosRESUMEN
Cytochrome c is one of the central mediators of the mitochondrial or the intrinsic apoptotic pathway. Mice harboring a 'knock-in' mutation of cytochrome c, impairing only its apoptotic function, have permitted studies on the essential role of cytochrome c-mediated apoptosis in various tissue homeostasis. To this end, we examined the role of cytochrome c in pancreatic ß-cells under homeostatic conditions and in diabetes models, including those induced by streptozotocin (STZ) and c-Myc. Previous studies have shown that both STZ- and c-Myc-induced ß-cell apoptosis is mediated through caspase-3 activation; however, the precise mechanism in these modes of cell death was not characterized. The results of our study show that lack of functional cytochrome c does not affect glucose homeostasis or pancreatic ß-cell mass under basal conditions. Moreover, the cytochrome c-mediated intrinsic apoptotic pathway is required for neither STZ- nor c-Myc-induced ß-cell death. We also observed that the extrinsic apoptotic pathway mediated through caspase-8 was not essential in c-Myc-induced ß-cell destruction. These findings suggest that cytochrome c is not required for STZ-induced ß-cell apoptosis and, together with the caspase-8-mediated extrinsic pathway, plays a redundant role in c-Myc-induced ß-cell apoptosis.
Asunto(s)
Apoptosis/fisiología , Citocromos c/metabolismo , Células Secretoras de Insulina/citología , Células Secretoras de Insulina/metabolismo , Animales , Apoptosis/genética , Caspasa 8/metabolismo , Citocromos c/deficiencia , Citocromos c/genética , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patología , Técnicas de Sustitución del Gen , Genes myc , Glucosa/metabolismo , Homeostasis , Ratones , Ratones Mutantes , Ratones Transgénicos , Proteínas Proto-Oncogénicas c-myc/metabolismo , Transducción de SeñalRESUMEN
Disruption of the X-chromosome fibroblast growth factor 16 (Fgf-16) gene, a member of the FGF-9 subfamily with FGF-20, was linked with an effect on cardiac development in two independent studies. However, poor trabeculation with lethality by embryonic day (E) 11.5 was associated with only one, involving maintenance in Black Swiss (Bsw) versus C57BL/6 mice. The aim of this study was to examine the potential influence of genetic background through breeding the null mutation onto an alternate (C57BL/6) background. After three generations, 25% of Fgf-16(-/Y) mice survived to adulthood, which could be reversed by reducing the contribution of the C57BL/6 genetic background by back crossing to another strain. There was no significant difference between FGF-9 and FGF-20 RNA levels in Fgf-16 null versus wild-type mice regardless of strain. However, FGF-8 RNA levels were reduced significantly in Bsw but not C57BL/6 mice. FGF-8 is linked to anterior heart development and like the FGF-9 subfamily is reportedly expressed at E10.5. Like FGF-16, neuregulin as well as signaling via ErbB2 and ErbB4 receptors have been linked to trabeculae formation and cardiac development around E10.5. Basal neuregulin, ErbB2, and ErbB4 as well as FGF-8, FGF-9, and FGF-16 RNA levels varied in Bsw versus C57BL/6 mice. These data are consistent with the ability of genetic background to modify the phenotype and affect embryonic survival in Fgf-16 null mice.
Asunto(s)
Anomalías Craneofaciales/embriología , Anomalías Craneofaciales/metabolismo , Factores de Crecimiento de Fibroblastos/metabolismo , Cardiopatías/embriología , Cardiopatías/metabolismo , Animales , Anomalías Craneofaciales/genética , ADN Helicasas/genética , ADN Helicasas/metabolismo , Embrión de Mamíferos/metabolismo , Femenino , Factores de Crecimiento de Fibroblastos/deficiencia , Cardiopatías/genética , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Fenotipo , Cromosoma X , Proteína Nuclear Ligada al Cromosoma XRESUMEN
A common feature among all forms of diabetes mellitus is a functional ß-cell mass insufficient to maintain euglycemia; therefore, the promotion of ß-cell growth and survival is a fundamental goal for diabetes prevention and treatment. Evidence has suggested that erythropoietin (EPO) exerts cytoprotective effects on nonerythroid cells. However, the influence of EPO on pancreatic ß cells and diabetes has not been evaluated to date. In this study, we report that recombinant human EPO treatment can protect against diabetes development in streptozotocin-induced and db/db mouse models of type 1 and type 2 diabetes, respectively. EPO exerts antiapoptotic, proliferative, antiinflammatory, and angiogenic effects within the islets. Using ß-cell-specific EPO receptor and JAK2 knockout mice, we show that these effects of EPO result from direct biological effects on ß cells and that JAK2 is an essential intracellular mediator. Thus, promotion of EPO signaling in ß cells may be a novel therapeutic strategy for diabetes prevention and treatment.
Asunto(s)
Apoptosis/efectos de los fármacos , Diabetes Mellitus Experimental/prevención & control , Eritropoyetina/farmacología , Células Secretoras de Insulina/efectos de los fármacos , Animales , Glucemia/metabolismo , Western Blotting , Proliferación Celular/efectos de los fármacos , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 1/prevención & control , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/prevención & control , Eritropoyetina/genética , Femenino , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Inmunohistoquímica , Insulina/metabolismo , Células Secretoras de Insulina/metabolismo , Janus Quinasa 2/genética , Janus Quinasa 2/metabolismo , Antígeno Ki-67/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Receptores de Eritropoyetina/genética , Receptores de Eritropoyetina/metabolismo , Proteínas Recombinantes/farmacología , Reacción en Cadena de la Polimerasa de Transcriptasa InversaAsunto(s)
Estrógenos/fisiología , Hematopoyesis/fisiología , Inmunidad/fisiología , Receptores de Estrógenos/fisiología , Animales , Enfermedades Autoinmunes/fisiopatología , Linfocitos B/fisiología , Estrógenos/genética , Células Madre Hematopoyéticas/fisiología , Humanos , Receptores de Estrógenos/genética , Timo/fisiologíaRESUMEN
FGF-16 has been reported to be preferentially expressed in the adult rat heart. We have investigated the expression of FGF-16 in the perinatal and postnatal heart and its functional significance in neonatal rat cardiac myocytes. FGF-16 mRNA accumulation was observed by quantitative RT-PCR between neonatal days 1 and 7, with this increased expression persisting into adulthood. FGF-2 has been shown to increase neonatal rat cardiac myocyte proliferative potential via PKC activation. Gene array analysis revealed that FGF-16 inhibited the upregulation by FGF-2 of cell cycle promoting genes including cyclin F and Ki67. Furthermore, the CDK4/6 inhibitor gene Arf/INK4A was upregulated with the combination of FGF-16 and FGF-2 but not with either factor on its own. The effect on Ki67 was validated by protein immunodetection, which also showed that FGF-16 significantly decreased FGF-2-induced Ki67 labeling of cardiac myocytes, although it alone had no effect on Ki67 labeling. Inhibition of p38 MAPK potentiated cardiac myocyte proliferation induced by FGF-2 but did not alter the inhibitory action of FGF-16. Receptor binding assay showed that FGF-16 can compete with FGF-2 for binding sites including FGF receptor 1. FGF-16 had no effect on activated p38, ERK1/2, or JNK/SAPK after FGF-2 treatment. However, FGF-16 inhibited PKC-alpha and PKC-epsilon activation induced by FGF-2 and, importantly, IGF-1. Collectively, these data suggest that expression and release of FGF-16 in the neonatal myocardium interfere with cardiac myocyte proliferative potential by altering the local signaling environment via modulation of PKC activation and cell cycle-related gene expression.
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Factores de Crecimiento de Fibroblastos/metabolismo , Miocitos Cardíacos/citología , Miocitos Cardíacos/fisiología , Envejecimiento/fisiología , Animales , Animales Recién Nacidos , Técnicas de Cultivo de Célula , Ciclo Celular/fisiología , División Celular , Activación Enzimática , Factores de Crecimiento de Fibroblastos/genética , Gliceraldehído-3-Fosfato Deshidrogenasas/genética , Cinética , Proteína Quinasa C/metabolismo , Ratas , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Transducción de SeñalRESUMEN
AIM: To investigate effect and mechanism of vasonatrin peptide (VNP) on Ca2+ activated K+ channels (K(Ca)) of vascular smooth muscle cells (VSMCs) isolated from rat mesentery arteries. METHODS: Changes of K(Ca) induced by VNP were measured by the means of whole cell recording mode of patch clamp, furthermore effects of HS-142-1(0.3 g/L), 8-Br-cGMP and methylene blue (MB) were observed. RESULTS: K(Ca) was significantly enhanced by VNP (10(-6) mol/L), which was mimicked by 8-Br-cGMP(10(-3) mol/L) and blocked completely by HS-142-1 or MB (2 x 10(-5) mol/L). CONCLUSION: VNP increases K(Ca) of VSMCs isolated from rat mesenteric arteries, by binding with natriuretic peptide guanylate cyclase-coupled receptors and increasing the intracellular level of cGMP in VSMCs.
Asunto(s)
Factor Natriurético Atrial/farmacología , Arterias Mesentéricas/efectos de los fármacos , Canales de Potasio Calcio-Activados/efectos de los fármacos , Animales , Masculino , Arterias Mesentéricas/citología , Arterias Mesentéricas/metabolismo , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/fisiología , Canales de Potasio Calcio-Activados/metabolismo , Ratas , Ratas Sprague-DawleyRESUMEN
In this study, we determined the effect of U50,488H (a selective kappa-opioid receptor agonist) on pulmonary artery in rats and investigated its prevention and treatment effects on hypoxic pulmonary hypertension (HPH). Isolated pulmonary arterial rings were superfused and the tension of the vessel was measured. The model of HPH was developed and indexes for hemodynamics and right ventricular hypertrophy were measured. We found that U50,488H relaxed the pulmonary artery rings in a dose-dependent manner and the effect was abolished by nor-binaltorphimine, a selective kappa-opioid receptor antagonist. Intravenous administration of U50,488H significantly lowered mean pulmonary artery pressure (mPAP) in normal rats and this effect was also abolished by nor-binaltorphimine. Hypoxia induced severe HPH in rats and intraperitoneal administration of U50,488H (every other day) during chronic hypoxia reduced mPAP and attenuated right ventricular hypertrophy compared with the control group. Moreover, acute intravenous administration of U50,488H after the rats subjected to chronic hypoxia for 4 weeks significantly lowered mPAP. Thus, U50,488H has significant vasorelaxant effect in rat pulmonary artery and has certain preventive and therapeutic application in HPH.