RESUMEN
A postprandial increase of translation mediated by eukaryotic Initiation Factor 6 (eIF6) occurs in the liver. Its contribution to steatosis and disease is unknown. In this study we address whether eIF6-driven translation contributes to disease progression. eIF6 levels increase throughout the progression from Non-Alcoholic Fatty Liver Disease (NAFLD) to hepatocellular carcinoma. Reduction of eIF6 levels protects the liver from disease progression. eIF6 depletion blunts lipid accumulation, increases fatty acid oxidation (FAO) and reduces oncogenic transformation in vitro. In addition, eIF6 depletion delays the progression from NAFLD to hepatocellular carcinoma, in vivo. Mechanistically, eIF6 depletion reduces the translation of transcription factor C/EBPß, leading to a drop in biomarkers associated with NAFLD progression to hepatocellular carcinoma and preserves mitochondrial respiration due to the maintenance of an alternative mTORC1-eIF4F translational branch that increases the expression of transcription factor YY1. We provide proof-of-concept that in vitro pharmacological inhibition of eIF6 activity recapitulates the protective effects of eIF6 depletion. We hypothesize the existence of a targetable, evolutionarily conserved translation circuit optimized for lipid accumulation and tumor progression.
Asunto(s)
Carcinoma Hepatocelular/genética , Neoplasias Hepáticas/genética , Enfermedad del Hígado Graso no Alcohólico/genética , Factores de Iniciación de Péptidos/genética , Biosíntesis de Proteínas/genética , Animales , Proteína beta Potenciadora de Unión a CCAAT/genética , Proteína beta Potenciadora de Unión a CCAAT/metabolismo , Carcinoma Hepatocelular/metabolismo , Línea Celular , Transformación Celular Neoplásica/efectos de los fármacos , Transformación Celular Neoplásica/genética , Transformación Celular Neoplásica/metabolismo , Clofazimina/farmacología , Dieta Alta en Grasa/efectos adversos , Progresión de la Enfermedad , Silenciador del Gen , Humanos , Lipogénesis/efectos de los fármacos , Lipogénesis/genética , Neoplasias Hepáticas/metabolismo , Masculino , Ratones Endogámicos C57BL , Ratones Noqueados , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Obesidad/etiología , Obesidad/genética , Obesidad/metabolismo , Factores de Iniciación de Péptidos/antagonistas & inhibidores , Factores de Iniciación de Péptidos/metabolismoRESUMEN
The transition from a naïve to an effector T cell is an essential event that requires metabolic reprogramming. We have recently demonstrated that the rapid metabolic changes that occur following stimulation of naïve T cells require the translation of preexisting mRNAs. Here, we provide evidence that translation regulates the metabolic asset of effector T cells. By performing ribosome profiling in human CD4+ Th1 cells, we show that the metabolism of glucose, fatty acids and pentose phosphates is regulated at the translational level. In Th1 cells, each pathway has at least one enzyme regulated at the translational level and selected enzymes have high translational efficiencies. mRNA expression does not predict protein expression. For instance, PKM2 mRNA is equally present in naïve T and Th1 cells, but the protein is abundant only in Th1. 5'-untranslated regions (UTRs) may partly account for this regulation. Overall we suggest that immunometabolism is controlled by translation.
Asunto(s)
Linfocitos T CD4-Positivos/metabolismo , Perfilación de la Expresión Génica/métodos , Redes y Vías Metabólicas/genética , Biosíntesis de Proteínas/genética , Ribosomas/genética , Células TH1/metabolismo , Regiones no Traducidas 5'/genética , Linfocitos T CD4-Positivos/citología , Diferenciación Celular/genética , Células Cultivadas , Ontología de Genes , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Humanos , ARN Mensajero/genética , ARN Mensajero/metabolismo , RNA-Seq/métodos , Ribosomas/metabolismo , Células TH1/citologíaRESUMEN
INTRODUCTION: A coronal seal is fundamental for a positive outcome to endodontic therapy. In this in vitro study, we evaluated the adaptation of composite resins in postendodontic restorations using optical coherence tomographic (OCT) imaging. Our null hypothesis was that there would be no difference in marginal adaptation to the pulp chamber floor between resin composites of different viscosities. METHODS: Thirty intact upper molars extracted for periodontal reasons were selected, endodontically treated, and filled with gutta-percha. The excess gutta-percha was entirely removed from the pulp chamber floor, and teeth were randomly divided into 3 groups (n = 10) according to the material used for the restoration: group 1: 0.5-mm horizontal layer of flowable composite followed by nanohybrid composite, group 2: bulk layering of bulk fill flowable composite; and group 3: oblique layering of nanohybrid composite. The degree of adaptation to the cavity floor was assessed using OCT imaging, and images were analyzed with the software program ImageJ (National Institutes of Health, Bethesda, MD) to assess the marginal gap between the composite and the pulp chamber floor. Collected data were statistically analyzed using analysis of variance testing, and statistical significance was set at P < .05. RESULTS: Flowable composites showed significantly better adaptation than traditional packable nanohybrid composites (P < .05). All significant differences were found between groups 1 and 2. CONCLUSIONS: Within the limitations of this OCT imaging-based in vitro study, it was concluded that the flowable composite (flow + nanofilled; flow bulk fill composite) adapted better to the pulp chamber floor than the packable nanohybrid composite resin. Further studies are necessary to confirm these results.