RESUMEN
The mammalian target of rapamycin (mTOR) pathway, which is essential for cell proliferation, is repressed in certain cell types in hypoxia. However, hypoxia-inducible factor 2α (HIF2α) can act as a proliferation-promoting factor in some biological settings. This paradoxical situation led us to study whether HIF2α has a specific effect on mTORC1 regulation. Here we show that activation of the HIF2α pathway increases mTORC1 activity by upregulating expression of the amino acid carrier SLC7A5. At the molecular level we also show that HIF2α binds to the Slc7a5 proximal promoter. Our findings identify a link between the oxygen-sensing HIF2α pathway and mTORC1 regulation, revealing the molecular basis of the tumor-promoting properties of HIF2α in von Hippel-Lindau-deficient cells. We also describe relevant physiological scenarios, including those that occur in liver and lung tissue, wherein HIF2α or low-oxygen tension drive mTORC1 activity and SLC7A5 expression.
Asunto(s)
Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Carcinoma de Células Renales/metabolismo , Neoplasias Renales/metabolismo , Transportador de Aminoácidos Neutros Grandes 1/metabolismo , Proteínas/metabolismo , Animales , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/genética , Sitios de Unión , Carcinoma de Células Renales/genética , Carcinoma de Células Renales/patología , Hipoxia de la Célula , Línea Celular Tumoral , Proliferación Celular , Regulación Neoplásica de la Expresión Génica , Células HEK293 , Humanos , Neoplasias Renales/genética , Neoplasias Renales/patología , Transportador de Aminoácidos Neutros Grandes 1/genética , Hígado/metabolismo , Pulmón/metabolismo , Diana Mecanicista del Complejo 1 de la Rapamicina , Ratones , Ratones Noqueados , Ratones SCID , Complejos Multiproteicos , Trasplante de Neoplasias , Regiones Promotoras Genéticas , Proteínas/genética , Interferencia de ARN , Transducción de Señal , Serina-Treonina Quinasas TOR , Factores de Tiempo , Transfección , Carga Tumoral , Regulación hacia Arriba , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/genética , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/metabolismoRESUMEN
Demand charges are widely used for commercial and industrial consumers. These costs are often not well known, let alone the effects that PV can have on them. This work proposes a methodology to assess the effect of PV on reducing these charges and to optimise the power to be contracted, using techniques taken from exploratory data analysis. This methodology is applied to five case studies of industrial consumers from different sectors in Spain, finding savings between 5 % and 11 % of demand charges in industries with continuous operation and up to 28 % in cases of discontinuous operation. These savings can be even greater if the maximum power that can be contracted is lower than the optimum. The demand charges in Spain consist of a fixed part proportional to the contracted power and a variable part depending on the power peaks exceeding it. Since for the variable part the coincident and non-coincident models coexist, a comparison is made between the two models, finding that in the general case PV users can achieve higher savings with the coincident model.
RESUMEN
Thrombospondin-1 (TSP-1) is a multifunctional matrix protein with antitumor activities due in part to its ability to inhibit angiogenesis, which in turn contributes to determine the fate of many tumours. Previous studies have shown that TSP-1 expression supports normal kidney angiostasis, and decreased TSP-1 levels contribute to the angiogenic phenotype of renal cell carcinomas (RCC). The loss of the von Hippel-Lindau tumour suppressor gene (VHL) in these tumours favours stabilization of the Hypoxia Inducible Factors (HIF), which in turn contribute to adapt tumour cells to hostile environments promoting tumour progression. However, HIF-independent regulation of certain genes might also be involved. We have previously shown that TSP-1 is regulated in hypoxia in clear cell RCC (ccRCC) in a HIF-independent manner; however, the effect of VHL protein (pVHL) on TSP-1 expression has not been evaluated. Our results proved that pVHL loss or mutation in its alpha or beta domain significantly decreased TSP-1 levels in ccRCC in a HIF-independent manner. Furthermore, this regulation proved to be important for ccRCC cells behaviour showing that decreased TSP-1 levels rendered ccRCC cells more migratory. This data substantiates a unique regulation pattern for TSP-1 in a pVHL-dependent manner, which may be relevant in the aggressiveness of ccRCC.
Asunto(s)
Carcinoma de Células Renales/patología , Regulación Neoplásica de la Expresión Génica , Neoplasias Renales/patología , Proteínas de Neoplasias/fisiología , Trombospondina 1/biosíntesis , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/fisiología , Línea Celular Tumoral , Movimiento Celular , Medio de Cultivo Libre de Suero , Regulación hacia Abajo , Técnicas de Silenciamiento del Gen , Humanos , Subunidad alfa del Factor 1 Inducible por Hipoxia/fisiología , Uniones Intercelulares/metabolismo , Mutación Missense , Invasividad Neoplásica , Proteínas de Neoplasias/biosíntesis , Proteínas de Neoplasias/genética , Dominios Proteicos/genética , Interferencia de ARN , ARN Mensajero/biosíntesis , ARN Mensajero/genética , ARN Neoplásico/biosíntesis , ARN Neoplásico/genética , ARN Interferente Pequeño/genética , Trombospondina 1/genética , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/antagonistas & inhibidores , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/genéticaRESUMEN
We report three patients aged 75-80 years observed in the Emergency Room with severe anaemia (requiring transfusion) due to a large abdominal wall haematoma while receiving standard prophylaxis against venous thromboembolism (40 mg/day enoxaparin for 6 days on average). All of them concomitantly received 100 mg/day aspirin because of previous ischaemic heart disease and presented similar clinical features: sudden onset of abdominal pain during a severe cough episode due to bronchial infection. A giant haematoma in the rectus abdominis muscle was recognized (by computed tomography) in every case. The cough has been related with this complication in some reports but its association with antiplatelet drugs and low molecular weight heparin could increase the risks in older patients. Sudden abdominal pain must alert the clinician to the rectus muscle sheath haematoma in order to avoid the risks of an exploratory laparotomy.
Asunto(s)
Pared Abdominal/patología , Aspirina/efectos adversos , Tos/complicaciones , Enoxaparina/efectos adversos , Hematoma/inducido químicamente , Anciano , Anciano de 80 o más Años , Relación Dosis-Respuesta a Droga , Quimioterapia Combinada , Femenino , Hematoma/diagnóstico por imagen , Humanos , Masculino , Isquemia Miocárdica/tratamiento farmacológico , Isquemia Miocárdica/prevención & control , Recto del Abdomen/diagnóstico por imagen , Tomografía Computarizada por Rayos XRESUMEN
The erythrocyte membrane was used as general model for the plasma membrane knowledge. Some of their structures are antigens from blood group systems being characterized at molecular and functional level as specific receptors, transporters or enzymes, even receptors for infectious agents. Plasmodium vivax malarial parasites require the Duffy blood group glycoprotein to penetrate into human red blood cells and the main antigen of P system (P1) is also the Parvovirus B19 receptor. Furthermore, these substances have an effect on several tissues, plasma and secretions involving pathogenic relationships. Certain aggressive Escherichia coli strains require the P1 antigen to attach to the urothelial cells, the Lewis(b) antigen is the gastric receptor for H. pylori, the anti-B from O or A individuals might protect them against the sepsis produced by E. coli, the Lewis group determines the CA-19.9 serum levels or the protective effect of breast milk. However, the most important effect could be the plasma hypocoagulability observed among the O blood group population (with lower factor VIII levels) in association with a reduced prevalence of thromboembolic diseases.
Asunto(s)
Antígenos de Grupos Sanguíneos , Susceptibilidad a Enfermedades , HumanosRESUMEN
BACKGROUND AND OBJECTIVES: Venous thromboembolism (VTE) involves inflammation and a relation with dyslipidemia which remains controversial. The vascular cell adhesion molecule-1 (VCAM-1) is a ligand expressed by activated endothelium (and recruits leukocytes) whose soluble form (sVCAM-1) increases in atherosclerosis, severe hypertriglyceridemia or deep vein thrombosis (DVT) in acute phase. We analyzed the association between VTE (> 6 months after), sVCAM-1 and lipid concentrations. DESIGN AND METHODS: Case-control study involving 126 consecutive patients (aged 25-80 years, 49% males) and 125 controls of similar age and gender. RESULTS: The patients had a more unfavorable lipid profile than controls [higher triglycerides (p<0.001), LDLc/HDLc ratio (p<0.01) or total cholesterol (TC) (p=0.07)] and higher sVCAM-1 concentration (p<0.01) even adjusting for arterial diseases. VTE was associated with extreme values of TC, LDL-c, triglycerides (>P90) and HDL-c (
Asunto(s)
Lípidos/sangre , Tromboembolia/epidemiología , Molécula 1 de Adhesión Celular Vascular/sangre , Adulto , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Colesterol/sangre , Interpretación Estadística de Datos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Vigilancia de la Población , Embolia Pulmonar/etiología , Factores de Riesgo , Factores Sexuales , Solubilidad , Tromboembolia/sangre , Triglicéridos/sangre , Trombosis de la Vena/sangre , Trombosis de la Vena/epidemiologíaRESUMEN
Thrombospondin-1 is a matricellular protein with potent antitumour activities, the levels of which determine the fate of many different tumours, including renal carcinomas. However, the factors that regulate this protein remain unclear. In renal carcinomas, hypoxic conditions enhance the expression of angiogenic factors that help adapt tumour cells to their hostile environment. Therefore, we hypothesized that anti-angiogenic factors should correspondingly be dampened. Indeed, we found that hypoxia decreased the thrombospondin-1 protein in several clear cell renal carcinoma cell lines (ccRCC), although no transcriptional regulation was observed. Furthermore, we proved that hypoxia stimulates multiple signals that independently contribute to diminish thrombospondin-1 in ccRCC, which include a decrease in the activity of oxygen-dependent prolylhydroxylases (PHDs) and activation of the PI3K/Akt signalling pathway. In addition, thrombospondin-1 regulation in hypoxia proved to be important for ccRCC cell migration and invasion.
Asunto(s)
Comunicación Autocrina , Carcinoma de Células Renales , Movimiento Celular , Trombospondina 1 , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Carcinoma de Células Renales/genética , Carcinoma de Células Renales/metabolismo , Hipoxia de la Célula , Línea Celular Tumoral , Movimiento Celular/genética , Humanos , Redes y Vías Metabólicas , Invasividad Neoplásica/genética , Proteína Oncogénica v-akt/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Trombospondina 1/genética , Trombospondina 1/metabolismoRESUMEN
Acute tubular necrosis (ATN) caused by ischemia/reperfusion (I/R) during renal transplantation delays allograft function. Identification of factors that mediate protection and/or epithelium recovery could help to improve graft outcome. We studied the expression, regulation and role of hypoxia inducible factor 1-alpha (HIF-1 α), using in vitro and in vivo experimental models of I/R as well as human post-transplant renal biopsies. We found that HIF-1 α is stabilized in proximal tubule cells during ischemia and unexpectedly in late reperfusion, when oxygen tension is normal. Both inductions lead to gene expression in vitro and in vivo. In vitro interference of HIF-1 α promoted cell death and in vivo interference exacerbated tissue damage and renal dysfunction. In pos-transplant human biopsies, HIF-1 α was expressed only in proximal tubules which exhibited normal renal structure with a significant negative correlation with ATN grade. In summary, using experimental models and human biopsies, we identified a novel HIF-1 α induction during reperfusion with a potential critical role in renal transplant.
Asunto(s)
Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Túbulos Renales Proximales/metabolismo , Túbulos Renales Proximales/patología , Daño por Reperfusión/metabolismo , Daño por Reperfusión/patología , Adulto , Anciano , Animales , Hipoxia de la Célula/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Células Epiteliales/enzimología , Células Epiteliales/patología , Femenino , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Inmunohistoquímica , Trasplante de Riñón , Necrosis Tubular Aguda/complicaciones , Necrosis Tubular Aguda/patología , Túbulos Renales Proximales/efectos de los fármacos , Masculino , Persona de Mediana Edad , Oxígeno/farmacología , Proteínas Proto-Oncogénicas c-akt/metabolismo , Ratas , Daño por Reperfusión/complicaciones , Daño por Reperfusión/genética , Transducción de Señal/efectos de los fármacos , Serina-Treonina Quinasas TOR/metabolismo , Transcripción Genética/efectos de los fármacos , Trasplante Homólogo , Adulto JovenRESUMEN
BACKGROUND: The onset of differentiation entails modifying the gene expression state of cells, to allow activation of developmental programs that are maintained repressed in the undifferentiated precursor cells [1, 2]. This requires a mechanism to change gene expression on a genome-scale. Recent evidence suggests that in mammalian stem cells, derepression of developmental regulators during differentiation involves a shift from stalled to productive elongation of their transcripts [3-5], but factors mediating this shift have not been identified and the evidence remains correlative. RESULTS: We report the identification of the MINIYO (IYO) gene, a positive regulator of transcriptional elongation that is essential for cells to initiate differentiation in Arabidopsis. IYO interacts with RNA polymerase II and the Elongator complex and is required to sustain global levels of transcriptional elongation activity, specifically in differentiating tissues. Accordingly, IYO is expressed in embryos, meristems, and organ primordia and not in mature tissues. Moreover, differential subcellular protein distribution further refines the domain of IYO function by directing nuclear accumulation, and thus its transcriptional activity, to cells initiating differentiation. Importantly, IYO overexpression induces premature cell differentiation and leads to meristem termination phenotypes. CONCLUSIONS: These findings identify IYO as a necessary and sufficient factor for initiating differentiation in Arabidopsis and suggest that the targeted nuclear accumulation of IYO functions as a transcriptional switch for this fate transition.
Asunto(s)
Proteínas de Arabidopsis/fisiología , Arabidopsis/citología , Diferenciación Celular/fisiología , Proteínas de Arabidopsis/genética , Meristema/citología , Mutación , Transcripción GenéticaRESUMEN
Von Hippel Lindau (Vhl) gene inactivation results in embryonic lethality. The consequences of its inactivation in adult mice, and of the ensuing activation of the hypoxia-inducible factors (HIFs), have been explored mainly in a tissue-specific manner. This mid-gestation lethality can be also circumvented by using a floxed Vhl allele in combination with an ubiquitous tamoxifen-inducible recombinase Cre-ER(T2). Here, we characterize a widespread reduction in Vhl gene expression in Vhl(floxed)-UBC-Cre-ER(T2) adult mice after dietary tamoxifen administration, a convenient route of administration that has yet to be fully characterized for global gene inactivation. Vhl gene inactivation rapidly resulted in a marked splenomegaly and skin erythema, accompanied by renal and hepatic induction of the erythropoietin (Epo) gene, indicative of the in vivo activation of the oxygen sensing HIF pathway. We show that acute Vhl gene inactivation also induced Epo gene expression in the heart, revealing cardiac tissue to be an extra-renal source of EPO. Indeed, primary cardiomyocytes and HL-1 cardiac cells both induce Epo gene expression when exposed to low O(2) tension in a HIF-dependent manner. Thus, as well as demonstrating the potential of dietary tamoxifen administration for gene inactivation studies in UBC-Cre-ER(T2) mouse lines, this data provides evidence of a cardiac oxygen-sensing VHL/HIF/EPO pathway in adult mice.
Asunto(s)
Eritropoyetina/genética , Silenciador del Gen , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Miocardio/metabolismo , Proteína Supresora de Tumores del Síndrome de Von Hippel-Lindau/genética , Animales , Animales Recién Nacidos , Peso Corporal/efectos de los fármacos , Células Cultivadas , Dieta , Eritropoyetina/metabolismo , Regulación de la Expresión Génica/efectos de los fármacos , Silenciador del Gen/efectos de los fármacos , Transportador de Glucosa de Tipo 1/genética , Transportador de Glucosa de Tipo 1/metabolismo , Subunidad alfa del Factor 1 Inducible por Hipoxia/genética , Integrasas/metabolismo , Ratones , Miocardio/patología , Miocitos Cardíacos/efectos de los fármacos , Miocitos Cardíacos/metabolismo , Especificidad de Órganos/efectos de los fármacos , Tamoxifeno/administración & dosificación , Tamoxifeno/farmacologíaRESUMEN
The fine regulation of mitochondrial function has proved to be an essential metabolic adaptation to fluctuations in oxygen availability. During hypoxia, cells activate an anaerobic switch that favors glycolysis and attenuates the mitochondrial activity. This switch involves the hypoxia-inducible transcription factor-1 (HIF-1). We have identified a HIF-1 target gene, the mitochondrial NDUFA4L2 (NADH dehydrogenase [ubiquinone] 1 alpha subcomplex, 4-like 2). Our results, obtained employing NDUFA4L2-silenced cells and NDUFA4L2 knockout murine embryonic fibroblasts, indicate that hypoxia-induced NDUFA4L2 attenuates mitochondrial oxygen consumption involving inhibition of Complex I activity, which limits the intracellular ROS production under low-oxygen conditions. Thus, reducing mitochondrial Complex I activity via NDUFA4L2 appears to be an essential element in the mitochondrial reprogramming induced by HIF-1.
Asunto(s)
Complejo I de Transporte de Electrón/antagonistas & inhibidores , Inducción Enzimática/fisiología , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Hipoxia/fisiopatología , Mitocondrias/fisiología , Consumo de Oxígeno/fisiología , Animales , Apoptosis/fisiología , Línea Celular , Complejo I de Transporte de Electrón/genética , Complejo I de Transporte de Electrón/metabolismo , Fibroblastos , Células HeLa , Humanos , Hipoxia/enzimología , Potencial de la Membrana Mitocondrial , Ratones , Ratones Noqueados , Análisis por Micromatrices , Ratas , Especies Reactivas de Oxígeno/metabolismo , Estadísticas no ParamétricasAsunto(s)
Neoplasias de la Coroides/terapia , Melanoma/terapia , Adulto , Anciano , Neoplasias de la Coroides/mortalidad , Enucleación del Ojo/métodos , Femenino , Humanos , Inmunoterapia , Masculino , Melanoma/mortalidad , Persona de Mediana Edad , Análisis de Supervivencia , Resultado del TratamientoRESUMEN
When oxygen becomes limiting, cells reduce mitochondrial respiration and increase ATP production through anaerobic fermentation of glucose. The Hypoxia Inducible Factors (HIFs) play a key role in this metabolic shift by regulating the transcription of key enzymes of glucose metabolism. Here we show that oxygen regulates the expression of the muscle glycogen synthase (GYS1). Hypoxic GYS1 induction requires HIF activity and a Hypoxia Response Element within its promoter. GYS1 gene induction correlated with a significant increase in glycogen synthase activity and glycogen accumulation in cells exposed to hypoxia. Significantly, knockdown of either HIF1alpha or GYS1 attenuated hypoxia-induced glycogen accumulation, while GYS1 overexpression was sufficient to mimic this effect. Altogether, these results indicate that GYS1 regulation by HIF plays a central role in the hypoxic accumulation of glycogen. Importantly, we found that hypoxia also upregulates the expression of UTP:glucose-1-phosphate urydylyltransferase (UGP2) and 1,4-alpha glucan branching enzyme (GBE1), two enzymes involved in the biosynthesis of glycogen. Therefore, hypoxia regulates almost all the enzymes involved in glycogen metabolism in a coordinated fashion, leading to its accumulation. Finally, we demonstrated that abrogation of glycogen synthesis, by knock-down of GYS1 expression, impairs hypoxic preconditioning, suggesting a physiological role for the glycogen accumulated during chronic hypoxia. In summary, our results uncover a novel effect of hypoxia on glucose metabolism, further supporting the central importance of metabolic reprogramming in the cellular adaptation to hypoxia.
Asunto(s)
Regulación Enzimológica de la Expresión Génica , Regulación de la Expresión Génica , Glucógeno Sintasa/metabolismo , Glucógeno/metabolismo , Subunidad alfa del Factor 1 Inducible por Hipoxia/metabolismo , Hipoxia , UTP-Glucosa-1-Fosfato Uridililtransferasa/metabolismo , Enzima Ramificadora de 1,4-alfa-Glucano/metabolismo , Animales , Genes Reporteros , Glucógeno/química , Humanos , Ratones , Modelos Biológicos , Músculos , Regiones Promotoras Genéticas , Interferencia de ARN , Elementos de RespuestaRESUMEN
The protein storage vacuole (PSV) is a plant-specific organelle that accumulates reserve proteins, one of the main agricultural products obtained from crops. Despite the importance of this process, the cellular machinery required for transport and accumulation of storage proteins remains largely unknown. Interfering with transport to PSVs has been shown to result in secretion of cargo. Therefore, secretion of a suitable marker could be used as an assay to identify mutants in this pathway. CLV3, a negative regulator of shoot stem cell proliferation, is an extracellular ligand that is rendered inactive when targeted to vacuoles. We devised an assay where trafficking mutants secrete engineered vacuolar CLV3 and show reduced meristems, a phenotype easily detected by visual inspection of plants. We tested this scheme in plants expressing VAC2, a fusion of CLV3 to the vacuolar sorting signal from the storage protein barley lectin. In this way, we determined that trafficking of VAC2 requires the SNARE VTI12 but not its close homologue, the conditionally redundant VTI11 protein. Furthermore, a vti12 mutant is specifically altered in transport of storage proteins, whereas a vti11 mutant is affected in transport of a lytic vacuole marker. These results demonstrate the specialization of VTI12 and VTI11 in mediating trafficking to storage and lytic vacuoles, respectively. Moreover, they validate the VAC2 secretion assay as a simple method to isolate genes that mediate trafficking to the PSV.