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The presence of hypoxic regions in solid tumors is an adverse prognostic factor for patient outcome. Here, we show that hypoxia induces the expression of Ephrin-A3 through a novel hypoxia-inducible factor (HIF)-mediated mechanism. In response to hypoxia, the coding EFNA3 mRNA levels remained relatively stable, but HIFs drove the expression of previously unknown long noncoding (lnc) RNAs from EFNA3 locus and these lncRNA caused Ephrin-A3 protein accumulation. Ephrins are cell surface proteins that regulate diverse biological processes by modulating cellular adhesion and repulsion. Mounting evidence implicates deregulated ephrin function in multiple aspects of tumor biology. We demonstrate that sustained expression of both Ephrin-A3 and novel EFNA3 lncRNAs increased the metastatic potential of human breast cancer cells, possibly by increasing the ability of tumor cells to extravasate from the blood vessels into surrounding tissue. In agreement, we found a strong correlation between high EFNA3 expression and shorter metastasis-free survival in breast cancer patients. Taken together, our results suggest that hypoxia could contribute to metastatic spread of breast cancer via HIF-mediated induction of EFNA3 lncRNAs and subsequent Ephrin-A3 protein accumulation.
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Neoplasias de la Mama/metabolismo , Sitios Genéticos , Factor 1 Inducible por Hipoxia/metabolismo , Proteínas de Neoplasias/metabolismo , ARN Largo no Codificante/biosíntesis , ARN Neoplásico/biosíntesis , Animales , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Hipoxia de la Célula/genética , Línea Celular Tumoral , Efrina-A3/genética , Efrina-A3/metabolismo , Femenino , Células Endoteliales de la Vena Umbilical Humana , Humanos , Factor 1 Inducible por Hipoxia/genética , Ratones , Ratones Desnudos , Metástasis de la Neoplasia , Proteínas de Neoplasias/genética , ARN Largo no Codificante/genética , ARN Neoplásico/genética , Pez CebraAsunto(s)
Enfermedad de Meniere/diagnóstico , Migraña con Aura/diagnóstico , Vértigo/diagnóstico , Pruebas de Función Vestibular , Neuronitis Vestibular/diagnóstico , Adulto , Audiometría , Umbral Auditivo/fisiología , Diagnóstico Diferencial , Femenino , Estudios de Seguimiento , Humanos , Masculino , Enfermedad de Meniere/fisiopatología , Persona de Mediana Edad , Migraña con Aura/fisiopatología , Estudios Retrospectivos , Vértigo/fisiopatología , Neuronitis Vestibular/fisiopatologíaRESUMEN
One of the hallmarks of malignancy is the polarization of tumor-associated macrophages (TAMs) from a pro-immune (M1-like) phenotype to an immune-suppressive (M2-like) phenotype. However, the molecular basis of the process is still unclear. MicroRNA (miRNA) comprises a group of small, non-coding RNAs that are broadly expressed by a variety of organisms and are involved in cell behaviors such as suppression or promotion of tumorigenesis. Here, we demonstrate that miR-19a-3p, broadly conserved among vertebrates, was downregulated in RAW264.7 macrophage cells of the M2 phenotype in conditoned medium of 4T1 mouse breast tumor cells. This downregulation correlated with an increased expression of the Fra-1 gene, which was reported to act as a pro-oncogene by supporting the invasion and progression of breast tumors. We found significant upregulation of miR-19a-3p in RAW264.7 macrophages after transfection with a miR-19a-3p mimic that resulted in a significant suppression of the expression of this gene. In addition, we could measure the activity of binding between miR-19a-3p and Fra-1 with a psiCHECK luciferase reporter system. Further, transfection of RAW264.7 macrophage cells with the miR-19a-3p mimic decreased the expression of the Fra-1 downstream genes VEGF, STAT3 and pSTAT3. Most importantly, the capacity of 4T1 breast tumor cells to migrate and invade was impaired in vivo by the intratumoral injection of miR-19a-3p. Taken together, these findings indicate that miR-19a-3p is capable of downregulating the M2 phenotype in M2 macrophages and that the low expression of this miRNA has an important role in the upregulation of Fra-1 expression and induction of M2 macrophage polarization.
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Antineoplásicos/farmacología , Macrófagos/efectos de los fármacos , Macrófagos/inmunología , Neoplasias Mamarias Experimentales/tratamiento farmacológico , Neoplasias Mamarias Experimentales/patología , MicroARNs/metabolismo , Proteínas Proto-Oncogénicas c-fos/metabolismo , Animales , Línea Celular Tumoral , Movimiento Celular/efectos de los fármacos , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Ratones , Ratones Endogámicos BALB C , MicroARNs/genética , Invasividad Neoplásica , Metástasis de la Neoplasia , Fenotipo , Proto-Oncogenes Mas , Proteínas Proto-Oncogénicas c-fos/genética , Transducción de Señal/efectos de los fármacos , Transducción de Señal/genética , Transfección , Microambiente Tumoral , Células U937RESUMEN
ObjetivoExaminar el perfil de pérdidas sanguíneas diagnósticas (extracciones analíticas) e iatrogénicas (técnicas de depuración extracorpórea [TDE]) en pacientes con trauma grave.MétodoEstudio descriptivo observacional prospectivo durante un año. Incluimos aquellos pacientes mayores de 15 años ingresados por trauma grave con Injury Severity Score (ISS) superior o igual a 16 puntos. Excluimos a aquellos pacientes a los que se hubiera indicado limitación del esfuerzo terapéutico. De 225 pacientes, con 1.619 días de evolución, analizamos volumen perdido/día/paciente, tipo de extracción, evolución clínica y presencia o no de TDE. Las variables se expresan como media±SD comparadas con la prueba de la t de Student.ResultadosEl promedio de pérdidas hemáticas/paciente/día ha sido de 55,5±32,2cm3. Encontramos diferencias estadísticamente significativas en el volumen sanguíneo extraído, comparando el primer día respecto al segundo (73,5±32,2 vs. 56,3±21,9cm3; p<0,001); evolución clínica (alta o éxitus) (54,8±33 vs. 60,7±24,9; p<0,05); gravedad (Injury Severity Score<31 o ≥31) (54,65±20 vs. 61,5±28,5; p<0,001) y sin TDE/TDE (50,9±18,9 vs. 97,2±72,6; p<0,001).ConclusionesLa mayor pérdida de sangre diagnóstica se produce en la fase de resucitación, en los pacientes que fallecen, en aquellos con mayor gravedad y los sometidos a TDE (AU)
ObjectiveTo analyze diagnostic (blood drawings) and iatrogenic (Continuous Renal Replacement Therapy, CRRT) blood losses (BL) in severe trauma patients.MethodA one-year descriptive, prospective and observational study. We included patients over 15 years of age, admitted with severe trauma and who had a score of ≥16 on the Injury Severity Index (ISS). Those patients in whom limitation of therapeutic effort had been indicated were excluded. A total of 225 patients with 1619 days of evolution were analyzed for volume of BL/day/patient, type of diagnostic test, clinical outcome and utilization of CRRT. The variables were described as mean ± standard deviation with the Student's T test.ResultsAverage blood loss of patient per day was 55.5±32.2cc. Statistically significant differences were found between the blood volume drawn when the first day was compared to the second day, 73.5±32.2 vs. 56.3±21.9 (p<0.001); clinical outcome (alive vs death) 54.8±33 vs. 60.7±24.9 (p<0.05); severity (ISS<31 or ≥31) 54.65±20 vs. 61.5±28.5 (p<0.001), No RRT vs RRT: 50.9±18.9 vs. 97.2±72.6 (p<0.001).ConclusionsThe greatest diagnostic BL occurs during the resuscitation phase, in the patients who die, in those with greater severity and those undergoing CRRT (AU)
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Humanos , Masculino , Femenino , Adulto , Heridas y Lesiones/sangre , Anemia/etiología , Pruebas Hematológicas/efectos adversos , Estudios ProspectivosRESUMEN
OBJECTIVE: To analyze diagnostic (blood drawings) and iatrogenic (Continuous Renal Replacement Therapy, CRRT) blood losses (BL) in severe trauma patients. METHOD: A one-year descriptive, prospective and observational study. We included patients over 15 years of age, admitted with severe trauma and who had a score of > or =16 on the Injury Severity Index (ISS). Those patients in whom limitation of therapeutic effort had been indicated were excluded. A total of 225 patients with 1619 days of evolution were analyzed for volume of BL/day/patient, type of diagnostic test, clinical outcome and utilization of CRRT. The variables were described as mean +/- standard deviation with the Student's T test. RESULTS: Average blood loss of patient per day was 55.5+/-32.2 cc. Statistically significant differences were found between the blood volume drawn when the first day was compared to the second day, 73.5+/-32.2 vs. 56.3+/-21.9 (p<0.001); clinical outcome (alive vs death) 54.8+/-33 vs. 60.7+/-24.9 (p<0.05); severity (ISS<31 or > or =31) 54.65+/-20 vs. 61.5+/-28.5 (p<0.001), No RRT vs RRT: 50.9+/-18.9 vs. 97.2+/-72.6 (p<0.001). CONCLUSIONS: The greatest diagnostic BL occurs during the resuscitation phase, in the patients who die, in those with greater severity and those undergoing CRRT.
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Anemia/etiología , Pruebas Hematológicas/efectos adversos , Heridas y Lesiones/sangre , Adulto , Femenino , Humanos , Puntaje de Gravedad del Traumatismo , Masculino , Estudios ProspectivosRESUMEN
The heads of three loggerhead sea turtles were disarticulated and imaged immediately to minimize postmortem changes and then frozen and sectioned. For computed tomography (CT) imaging, the heads were positioned in ventral recumbency. Transverse CT images with soft-tissue window were obtained from the olfactory sac region to the temporomandibular joint region. After CT imaging, the heads were sectioned and the gross sections were compared to CT images, to assist in the accurate identification of the anatomic structures. Different clinically relevant anatomic structures were identified and labelled in two series of photographs (CT images and anatomic cross-sections). CT images provided good differentiation between the bones and the soft tissues of the head. The information presented in this paper should serve as an initial reference to evaluate CT images of the head of the loggerhead sea turtle and to assist in the interpretation of lesions of this region.
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Cabeza/anatomía & histología , Tortugas/anatomía & histología , Animales , Tomografía Computarizada por Rayos X/veterinariaRESUMEN
The ascomycete Fusarium fujikuroi produces carotenoids by means of the enzymes encoded by three car genes. The enzymes encoded by carRA and carB are responsible of the synthesis of beta-carotene and torulene, respectively, while the product encoded by carT cleaves torulene to produce the acidic xanthophyll neurosporaxanthin. carRA and carB are found in a cluster with a third gene, carO, which codes for an opsin-like protein. However, no information is available on the sequence or chromosomal location of carT, which has been identified only by mutant analysis. Transcription of the three clustered genes is stimulated by light and by mutations in a regulatory gene, leading to overproduction of carotenoids. We have now identified a fourth gene in the car cluster, called carX, which codes for a protein similar to known carotenoid-cleaving oxygenases. carX is transcribed divergently from carRA, and exhibits the same transcriptional pattern as carRA, carB and carO. Targeted deletion of carX resulted in a phenotype characterized by a significant increase in the overall carotenoid content. In the dark, the carX mutants accumulate at least five times more carotenoids than the wild type, and exhibit partial derepression of carRA and carB transcription. The mutants also show more intense pigmentation in the light, but the increase in the carotenoid content relative to the wild type is less than twofold. Under these conditions, the mutants also show a relative increase in the amounts of phytoene and cyclic carotenoids formed, suggesting that CarRA activity is enhanced.
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Fusarium/genética , Familia de Multigenes/genética , Oxigenasas/genética , Filogenia , Secuencia de Aminoácidos , Secuencia de Bases , Northern Blotting , Southern Blotting , Carotenoides/biosíntesis , Carotenoides/metabolismo , Análisis por Conglomerados , Cartilla de ADN , Fusarium/enzimología , Componentes del Gen , Vectores Genéticos/genética , Datos de Secuencia Molecular , Mutación/genética , Oxigenasas/química , Oxigenasas/metabolismo , Alineación de Secuencia , Análisis de Secuencia de ADNRESUMEN
No disponible
No disponible
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Humanos , Anfetaminas/farmacología , Trastornos Relacionados con SustanciasRESUMEN
No disponible
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Ratones , Animales , Cardiomegalia/etiología , Cardiomegalia/fisiopatología , Ácidos Grasos/metabolismo , Glucosa/metabolismo , Receptores Activados del Proliferador del Peroxisoma/fisiología , Receptores Activados del Proliferador del Peroxisoma/farmacocinética , Cardiomegalia/tratamiento farmacológico , Cardiomegalia/inducido químicamente , Miocitos Cardíacos/fisiología , PPAR alfa/fisiología , PPAR gamma/fisiología , Estrés OxidativoAsunto(s)
Extremidad Inferior , Embolia Pulmonar/etiología , Escleroterapia/efectos adversos , Várices/terapia , Anticoagulantes/uso terapéutico , Femenino , Humanos , Persona de Mediana Edad , Embolia Pulmonar/diagnóstico por imagen , Embolia Pulmonar/tratamiento farmacológico , Soluciones Esclerosantes/administración & dosificación , Soluciones Esclerosantes/efectos adversos , Tomografía Computarizada Espiral , Resultado del TratamientoRESUMEN
No disponible
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Persona de Mediana Edad , Humanos , Femenino , Accidentes Domésticos , Extremidad Inferior , Resultado del Tratamiento , Várices , Datura stramonium , Intoxicación por Plantas , Soluciones Esclerosantes , Semillas , Familia , Escleroterapia , Embolia Pulmonar , Anticoagulantes , Tomografía Computarizada EspiralRESUMEN
Peroxisome proliferator-activated receptors (PPARs) are ligand-activated transcription factors which form a subfamily of the nuclear receptor gene family. This subfamily consists of three isotypes, alpha (NR1C1), gamma (NR1C3), and beta/delta (NRC1C2) with a differential tissue distribution. PPARalpha is expressed primarily in tissues with a high level of fatty acid catabolism such as liver, brown fat, kidney, heart and skeletal muscle. PPARbeta is ubiquitously expressed, and PPARgamma has a restricted pattern of expression, mainly in white and brown adipose tissues, whereas other tissues such as skeletal muscle and heart contain limited amounts. Furthermore, PPARalpha and gamma isotypes are expressed in vascular cells including endothelial and smooth muscle cells and macrophages/foam cells. PPARs are activated by ligands, such as naturally occurring fatty acids, which are activators of all three PPAR isotypes. In addition to fatty acids, several synthetic compounds, such as fibrates and thiazolidinediones, bind and activate PPARalpha and PPARgamma, respectively. In order to be transcriptionally active, PPARs need to heterodimerize with the retinoid-X-receptor (RXR). Upon activation, PPAR-RXR heterodimers bind to DNA specific sequences called peroxisome proliferator-response elements (PPRE) and stimulate transcription of target genes. PPARs play a critical role in lipid and glucose homeostasis, but lately they have been implicated as regulators of inflammatory responses. The first evidence of the involvement of PPARs in the control of inflammation came from the PPARalpha null mice, which showed a prolonged inflammatory response. PPARalpha activation results in the repression of NF-kappaB signaling and inflammatory cytokine production in different cell-types. A role for PPARgamma in inflammation has also been reported in monocyte/macrophages, where ligands of this receptor inhibited the activation of macrophages and the production of inflammatory cytokines (TNFalpha, interleukin 6 and 1beta), although part of the anti-inflammatory effects of these ligands seems to be mediated by a mechanism not involving PPARgamma. All these findings suggest a role of PPARs in the control of the inflammatory response with potential therapeutic applications in inflammation-related diseases.
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Antiinflamatorios/farmacología , Inflamación/patología , Receptores Citoplasmáticos y Nucleares/efectos de los fármacos , Factores de Transcripción/efectos de los fármacos , Animales , Antiinflamatorios/uso terapéutico , Humanos , Inflamación/tratamiento farmacológico , Inflamación/fisiopatología , Receptores Citoplasmáticos y Nucleares/fisiología , Factores de Transcripción/fisiologíaRESUMEN
Uncoupling proteins (UCPs) are mitochondrial membrane proton transporters that uncouple respiration from oxidative phosphorylation by dissipating the proton gradient across the membrane. Treatment of C2C12 myotubes for 24 h with 40 microM etomoxir, an irreversible inhibitor of carnitine palmitoyltransferase I (CPT-I), up-regulated uncoupling protein 3 (UCP-3) mRNA levels (2-fold induction), whereas UCP-2 mRNA levels were not modified. Etomoxir treatment also caused a 2.5-fold induction in M-CPT-I (muscle-type CPT-I) mRNA levels. In contrast, other well-known peroxisome proliferator-activated receptor alpha (PPAR alpha) target genes, such as acyl-CoA oxidase and medium-chain acyl-CoA dehydrogenase, were not affected, suggesting that this transcription factor was not involved in the effects of etomoxir. Since it has been reported that CPT-I inhibition by etomoxir leads to a further increase in ceramide synthesis, we test the possibility that ceramides were involved in the changes reported. Similarly to etomoxir, addition of 20 microM C(2)-ceramide to C2C12 myotubes for 3, 6 and 9 h resulted in increased UCP-3 and M-CPT-I mRNA levels. These results indicate that the effects on UCP-3 mRNA levels could be mediated by increased ceramide synthesis.
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Proteínas Portadoras/genética , Compuestos Epoxi/farmacología , Animales , Carnitina O-Palmitoiltransferasa/antagonistas & inhibidores , Carnitina O-Palmitoiltransferasa/genética , Línea Celular , Ceramidas/biosíntesis , Inhibidores Enzimáticos/farmacología , Canales Iónicos , Ratones , Proteínas Mitocondriales , ARN Mensajero/análisis , ARN Mensajero/biosíntesis , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Esfingosina/análogos & derivados , Esfingosina/farmacología , Proteína Desacopladora 3 , Regulación hacia ArribaRESUMEN
We studied whether two typical effects of fibrates, induction of stearoyl-CoA desaturase (EC 1.14.99.5) and peroxisome proliferation, are related. The effect of bezafibrate on the activity and mRNA of stearoyl-CoA desaturase and acyl-CoA oxidase in the liver and epididymal white adipose tissue of male Sprague-Dawley rats was determined. The same parameters were measured in HepG2 cells, a cell line resistant to peroxisome proliferation, following incubation with ciprofibrate. Bezafibrate increased the hepatic mRNA levels (14.5-fold on day 7) and activity (9.3-fold on day 15) of acyl-CoA oxidase. Stearoyl-CoA desaturase mRNA levels were transiently increased (2.7-fold on day 7), while its activity remained increased at the end of the treatment (2.4-fold). In white adipose tissue, bezafibrate increased the mRNA (5-fold) and activity (1.9-fold) of acyl-CoA oxidase, while stearoyl-CoA desaturase was not modified. Ciprofibrate addition to HepG2 cells cultured in 7% fetal bovine serum (FBS) only increased the stearoyl-CoA desaturase mRNA (1.9-fold). When cells were cultured in 0.5% FBS, ciprofibrate increased acyl-CoA oxidase mRNA (2.2-fold), while the increase in stearoyl-CoA desaturase mRNA was identical (1.9-fold). Further, its activity was also increased (1.5-fold). Incubation of HepG2 cells in the presence of cycloheximide did not alter the capacity of ciprofibrate to induce stearoyl-CoA desaturase mRNA, whereas the presence of actinomycin abolished the induction. In addition, preincubation of HepG2 cells with ciprofibrate increased the rate of stearoyl-CoA desaturase mRNA degradation. The results presented in this study suggest that fibrates induce stearoyl-CoA desaturase activity and mRNA levels independently of peroxisome proliferation.
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Tejido Adiposo/efectos de los fármacos , Bezafibrato/farmacología , Ácido Clofíbrico/farmacología , Oxidorreductasas/biosíntesis , Estearoil-CoA Desaturasa/biosíntesis , Acil-CoA Oxidasa , Tejido Adiposo/enzimología , Animales , Ácido Clofíbrico/análogos & derivados , Medios de Cultivo/análisis , Inducción Enzimática/efectos de los fármacos , Ácidos Fíbricos , Humanos , Hipolipemiantes/farmacología , Hígado/efectos de los fármacos , Hígado/enzimología , Masculino , Oxidorreductasas/genética , ARN Mensajero/biosíntesis , ARN Mensajero/efectos de los fármacos , Ratas , Ratas Sprague-Dawley , Estearoil-CoA Desaturasa/genética , Células Tumorales CultivadasRESUMEN
Rats treated with bezafibrate, a PPAR activator, gain less body weight and increase daily food intake. Previously, we have related these changes to a shift of thermogenesis from brown adipose tissue to white adipose tissue attributable to bezafibrate, which induces uncoupling proteins (UCP), UCP-1 and UCP-3, in rat white adipocytes. Nevertheless, UCP induction was weak, implying additional mechanisms in the change of energy homeostasis produced by bezafibrate. Here we show that bezafibrate, in addition to inducing UCPs, modifies energy homeostasis by directly inducing aco gene expression and peroxisomal fatty acid beta-oxidation in white adipose tissue. Further, bezafibrate significantly reduced plasma triglyceride and leptin concentrations, without modifying the levels of PPARgamma or ob gene in white adipose tissue. These results indicate that bezafibrate reduces the amount of fatty acids available for triglyceride synthesis in white adipose tissue.
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Tejido Adiposo/metabolismo , Bezafibrato/farmacología , Ácidos Grasos/metabolismo , Hipolipemiantes/farmacología , Oxidorreductasas/metabolismo , Oxígeno/metabolismo , Peroxisomas/metabolismo , Acil-CoA Oxidasa , Animales , Peso Corporal/efectos de los fármacos , Células Cultivadas , Colesterol/sangre , Leptina/sangre , Hígado/efectos de los fármacos , Hígado/metabolismo , Masculino , ARN/metabolismo , ARN Mensajero/metabolismo , Ratas , Ratas Sprague-Dawley , Receptores Citoplasmáticos y Nucleares/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Temperatura , Factores de Tiempo , Factores de Transcripción/metabolismo , Triglicéridos/sangreRESUMEN
Uncoupling proteins (UCPs) are mitochondrial membrane proton transporters that uncouple respiration from oxidative phosphorylation by dissipating the proton gradient across the membrane. We studied the direct effect of several peroxisome proliferator-activated receptor (PPAR) ligands on UCP-3 and UCP-2 mRNA expression in C2C12 myotubes for 24 h. In the absence of exogenous fatty acids, treatment of C2C12 cells with a selective PPARalpha activator (Wy-14,643) or a non-selective PPAR activator (bezafibrate) did not affect the expression of UCP-3 mRNA levels, whereas UCP-2 expression was slightly increased. In contrast, troglitazone, a thiazolidinedione which selectively activates PPARgamma, strongly decreased UCP-3 and UCP-2 mRNA levels. Another thiazolidinedione, ciglitazone, had the same effect, but to a lower extent, suggesting that PPARgamma activation is involved. Further, the presence of 0.5 mM oleic acid strongly increased UCP-3 mRNA levels and troglitazone addition failed to block the effect of this fatty acid. The drop in UCP expression after thiazolidinedione treatment correlated well with a reduction in PPARalpha mRNA levels produced by this drug, linking the reduction in PPARalpha mRNA levels with the down-regulation of UCP mRNA in C2C12 myotubes after thiazolidinedione treatment.
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Proteínas Portadoras/genética , Regulación hacia Abajo/efectos de los fármacos , Proteínas de Transporte de Membrana , Proteínas Mitocondriales , Músculos/efectos de los fármacos , Proteínas/genética , Tiazoles/farmacología , Tiazolidinedionas , Acil-CoA Deshidrogenasa , Animales , Atorvastatina , Bezafibrato/farmacología , Carnitina O-Palmitoiltransferasa/genética , Línea Celular , Colesterol/farmacología , Cromanos/farmacología , Ácido Graso Desaturasas/genética , Ácidos Heptanoicos/farmacología , Hipoglucemiantes/farmacología , Canales Iónicos , Ligandos , Ratones , Músculos/citología , Músculos/enzimología , Músculos/metabolismo , Ácido Oléico/farmacología , Proliferadores de Peroxisomas/farmacología , Pirimidinas/farmacología , Pirroles/farmacología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptores Citoplasmáticos y Nucleares/agonistas , Receptores Citoplasmáticos y Nucleares/genética , Receptores Citoplasmáticos y Nucleares/metabolismo , Factores de Transcripción/agonistas , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Triazenos/farmacología , Troglitazona , Proteína Desacopladora 2 , Proteína Desacopladora 3RESUMEN
Uncoupling proteins (UCPs) are inner mitochondrial membrane transporters which act as pores for H(+) ions, dissipating the electrochemical gradient that develops during mitochondrial respiration at the expense of ATP synthesis. We have studied the effects of two fibrates, bezafibrate and Wy-14,643, on UCP-3 and UCP-2 mRNA levels in primary monolayer cultures of rat adipocytes and undifferentiated preadipocytes. Treatment with both PPARalpha activators for 24 h up-regulated UCP-3 mRNA levels. Thus, bezafibrate treatment resulted in an 8-fold induction in UCP-3 mRNA levels in preadipocytes compared with the 3.5-fold induction observed in adipocytes. Differences in the induction of UCP-3 between these cells correlated well with the higher expression of PPARalpha and RXRalpha mRNA values in preadipocytes compared to adipocytes. Wy-14,643 caused similar effects on UCP-3 mRNA expression. In contrast to UCP-3, UCP-2 mRNA levels were only slightly modified by bezafibrate in adipocytes. The induction in UCP-3 expression was not accompanied by changes in the mitochondrial membrane potential of rat primary preadipocytes after bezafibrate or Wy-14,643 treatment. Since it has been proposed that UCP-3 could be involved in the regulation of the use of fatty acids as fuel substrates, the UCP-3 induction achieved after bezafibrate and Wy-14, 643 treatment may indicate a higher oxidation of fatty acids, limiting their availability to be stored as triglycerides. This change may result in a reduced rate of conversion of preadipocytes to adipocytes, which directly affects fat depots.
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Adipocitos/efectos de los fármacos , Adipocitos/metabolismo , Bezafibrato/farmacología , Proteínas Portadoras/genética , Pirimidinas/farmacología , ARN Mensajero/genética , ARN Mensajero/metabolismo , Receptores Citoplasmáticos y Nucleares/metabolismo , Factores de Transcripción/metabolismo , Animales , Secuencia de Bases , Células Cultivadas , Cartilla de ADN/genética , Canales Iónicos , Potenciales de la Membrana/efectos de los fármacos , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Proteínas Mitocondriales , Proliferadores de Peroxisomas/farmacología , Ratas , Células Madre/efectos de los fármacos , Células Madre/metabolismo , Proteína Desacopladora 3RESUMEN
Peroxisome proliferator-activated receptor-alpha (PPARalpha) is responsible for the hypolipidemic, peroxisome proliferation and carcinogenic effects of fibrates. Rats and mice are responsive, but guinea pigs and primates are resistant to the proliferative and carcinogenic effects of these drugs, but the hypolipidemic effect is still manifest. It is not yet clear whether humans should be considered unresponsive, and there is concern about the long-term safety of fibrates. We present molecular evidence for the reported resistance of human cells to peroxisome proliferation by describing a deficient interaction of nuclear extracts from human cells with an acyl-CoA oxidase (ACO)-peroxisome proliferator response element probe upon fibrate addition. Electrophoretic mobility shift assay analysis showed that ciprofibrate elicited a concentration-dependent increase in the binding of nuclear extracts from cells of rat (Morris) and human (HepG2) origin to an ACO-peroxisome proliferator response element probe, although in HepG2 cells the increase was of marginal statistical significance. In Morris cells, the increase was more marked than in HepG2 cells (4-fold versus 1.5-fold at 0.2 mM ciprofibrate), and maximal binding was achieved earlier in Morris (30 min) than in HepG2 cells (3 h). Morris cells responded to the addition of ciprofibrate by increasing the levels of ACO mRNA, whereas HepG2 did not. The ratio between PPARbeta/PPARalpha mRNAs was higher in HepG2 cells than in Morris cells (3.2 versus 1.9), pointing to an antagonizing effect of PPARbeta on PPARalpha activity. These results were obtained in untransfected cells expressing their own basal set of receptors. We also provide evidence of the translocation of PPARalpha from the cytosol to the nucleus upon activation by ciprofibrate.