TGFβ impairs HNF1α functional activity in Epithelial-to-Mesenchymal Transition interfering with the recruitment of CBP/p300 acetyltransferases

The cytokine transforming growth factor β (TGFβ) plays a crucial role in the induction of both epithelial-to-mesenchymal transition (EMT) program and fibro-cirrhotic process in the liver, where it contributes also to organ inflammation following several chronic injuries. All these pathological situations greatly increase the risk of hepatocellular carcinoma (HCC) and contribute to tumor progression. In particular, late-stage HCCs are characterized by constitutive activation of TGFβ pathway and by an EMT molecular signature leading to the acquisition of invasive and metastatic properties. In these pathological conditions, the cytokine has been shown to induce the transcriptional downregulation of HNF1α, a master regulator of the epithelial/hepatocyte differentiation and of the EMT reverse process, the mesenchymal-to-epithelial transition (MET). Therefore, the restoration of HNF1α expression/activity has been proposed as targeted therapeutic strategy for liver fibro-cirrhosis and late-stage HCCs. In this study, TGFβ is found to trigger an early functional inactivation of HNF1α during EMT process that anticipates the effects of the transcriptional downregulation of its own gene. Mechanistically, the cytokine, while not affecting the HNF1α DNA-binding capacity, impaired its ability to recruit CBP/p300 acetyltransferases on target gene promoters and, consequently, its transactivating function. The loss of HNF1α capacity to bind to CBP/p300 and HNF1α functional inactivation have been found to correlate with a change of its posttranslational modification profile. Collectively, the results obtained in this work unveil a new level of HNF1α functional inactivation by TGFβ and contribute to shed light on the early events triggering EMT in hepatocytes. Moreover, these data suggest that the use of HNF1α as anti-EMT tool in a TGFβ-containing microenvironment may require the design of new therapeutic strategies overcoming the TGFβ-induced HNF1α inactivation

ADAR1 restricts LINE-1 retrotransposition

Abstract Adenosine deaminases acting on RNA (ADARs) are involved in RNA editing that converts adenosines to inosines in double-stranded RNAs. ADAR1 was demonstrated to be functional on different viruses exerting either antiviral or proviral effects. Concerning HIV-1, several studies showed that ADAR1 favors viral replication. The aim of this study was to investigate the composition of the ADAR1 ribonucleoprotein complex during HIV-1 expression. By using a dual-tag affinity purification procedure in cells expressing HIV-1 followed by mass spectrometry analysis, we identified 14 non-ribosomal ADAR1-interacting proteins, most of which are novel. A significant fraction of these proteins were previously demonstrated to be associated to the Long INterspersed Element 1 (LINE1 or L1) ribonucleoparticles and to regulate the life cycle of L1 retrotransposons that continuously re-enter host-genome.Hence, we investigated the function of ADAR1 in the regulation of L1 activity.By using different cell-culture based retrotransposition assays in HeLa cells, we demonstrated a novel function of ADAR1 as suppressor of L1 retrotransposition. Apparently, this inhibitory mechanism does not occur through ADAR1 editing activity. Furthermore, we showed that ADAR1 binds the basal L1 RNP complex. Overall, these data support the role of ADAR1 as regulator of L1 life cycle

Ferritin heavy chain Is the host factor responsible for HCV-Induced inhibition of apoB-100 production and is required for efficient viral infection

Hepatic fat export occurs by apolipoprotein B-100-containing lipoprotein production, whereas impaired production leads to liver steatosis. Hepatitis C virus (HCV) infection is associated to dysregulation of apoB-100 secretion and steatosis; however, the molecular mechanism by which HCV affects the apoB-100 secretion is not understood. Here, combining quantitative proteomics and computational biology, we propose ferritin heavy chain (Fth) as being the cellular determinant of apoB-100 production inhibition. By means of molecular analyses, we found that HCV nonstructural proteins and NS5A appear to be sufficient for inducing Fth up-regulation. Fth in turn was found to inhibit apoB-100 secretion leading to increased intracellular degradation via proteasome. Notably, intracellular Fth down-regulation by siRNA restores apoB-100 secretion. The inverse correlation between ferritin and plasma apoB-100 concentrations was also found in JFH-1 HCV cell culture systems (HCVcc) and HCV-infected patients. Finally, Fth expression was found to be required for robust HCV infection. These observations provide a further molecular explanation for the onset of liver steatosis and allow for hypothesizing on new therapeutic and antiviral strategies

SILAC labeling coupled to shotgun proteomics analysis of membrane proteins of liver stem/hepatocyte allows to candidate the inhibition of TGF-beta pathway as causal to differentiation

International audienceDespite extensive research on hepatic cells precursors and their differentiated states, much remains to be learned about the mechanism underlying the self-renewal and differentiation. We apply the SILAC (stable isotope labeling by amino acids in cell culture) approach to quantitatively compare the membrane proteome of the resident liver stem cells (RLSCs) and their progeny spontaneously differentiated into epithelial/hepatocyte (RLSCdH). By means of nanoLC-MALDI-TOF/TOF approach, we identified and quantified 248 membrane proteins and 57 of them were found modulated during hepatocyte differentiation. Functional clustering of differentially expressed proteins by Ingenuity Pathway Analysis revealed that the most of membrane proteins found to be modulated are involved in cell-to-cell signaling/interaction pathways. Moreover, the upstream prediction analysis of proteins involved in cell-to-cell signaling and interaction unveiled that the activation of the mesenchymal to epithelial transition (MET), by the repression of TGFB1/Slug signaling, may be causal to hepatocyte differentiation. Taken together, this study increases the understanding of the underlying mechanisms modulating the complex biological processes of hepatic stem cell proliferation and differentiation

N-Acetylcysteine Inhibits Lipids Production in Mature Adipocytes through the Inhibition of Peroxisome Proliferator-Activated Receptor

Aims: Reports regarding the effects of antioxidants in obesity have been contradictory. AntioxidantN-acetylcysteine is usually considered a nutritional supplement. Our aim is to evaluate bioactivity ofN-acetylcysteine (NAC) on mature adipocytes, which is a close model to in vivo condition.Study Design: In vitro study.Place and Duration of Study: Department of Basic Science (Universidad Nacional de Lujan),Department of Chemical Biology (Universidad de Buenos Aires), CONICET ? INEDES andCONICET ? IQUIBICEN, between March 2017 and June 2019.Methodology: We evaluated the bioactivity of different concentrations of NAC for 5 days (0.01 mMto 5 mM) on fully differentiated 3T3-L1 cells (mature adipocytes).Results: We demonstrated that NAC treatment was not toxic to mature adipocytes. Only 5mM NACinhibited reactive oxygen species production. 5 mM NAC treatment resulted in a 60% decrease incellular triglycerides content and inhibited 70% cholesterol accumulation. We also determined themRNA and protein expression levels of Peroxisome Proliferator-Activated Receptor as well as,mRNA levels of lipid protein Perilipin in NAC treated adipocytes; we observed that 5mM NACtreatment caused nearly 30% decrease in the expression of these parameters.Conclusion: These results suggest that NAC could avoid lipid accumulation in mature adipocytes;the antioxidant NAC could be beneficial in obesity treatment.Fil: Soto, Daniela. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; ArgentinaFil: Martini, Claudia Noemí. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; ArgentinaFil: Frontera, Evelyn Micaela. Universidad Nacional de Luján. Departamento de Ciencias Básicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Montaldo, Laura Andrea. Universidad Nacional de Luján. Departamento de Ciencias Básicas; ArgentinaFil: Vila, Maria del Carmen. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Calvo, Juan Carlos. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Biología y Medicina Experimental. Fundación de Instituto de Biología y Medicina Experimental. Instituto de Biología y Medicina Experimental; ArgentinaFil: Guerra, Liliana Noemi. Universidad Nacional de Luján. Instituto de Ecología y Desarrollo Sustentable. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Ecología y Desarrollo Sustentable; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Biológica; Argentin

The lncRNA HOTAIR transcription is controlled by HNF4α-induced chromatin topology modulation

The expression of the long noncoding RNA HOTAIR (HOX Transcript Antisense Intergenic RNA) is largely deregulated in epithelial cancers and positively correlates with poor prognosis and progression of hepatocellular carcinoma and gastrointestinal cancers. Furthermore, functional studies revealed a pivotal role for HOTAIR in the epithelial-to-mesenchymal transition, as this RNA is causal for the repressive activity of the master factor SNAIL on epithelial genes. Despite the proven oncogenic role of HOTAIR, its transcriptional regulation is still poorly understood. Here hepatocyte nuclear factor 4-α (HNF4α), as inducer of epithelial differentiation, was demonstrated to directly repress HOTAIR transcription in the mesenchymal-to epithelial transition. Mechanistically, HNF4α was found to cause the release of a chromatin loop on HOTAIR regulatory elements thus exerting an enhancer-blocking activity

Aprendizaje abierto y aprendizaje flexible. Más allá de formatos y espacios tradicionales

La sociedad se ha transformado radicalmente en los últimos veinte años, y las tecnologías de la información y la comunicación han tenido mucho que ver con ello. Las dimensiones de espacio y tiempo, y los conceptos de comunicación e información se han modificado a tal punto que han impactado en el trabajo, las relaciones sociales y la vida cotidiana. Sin embargo, a la par que las tecnologías modificaron grandemente la vida de las sociedades, las relaciones laborales y hasta el poder, su incorporación produj nuevas desigualdades sociales. Fundamentalmente desigualdad en las oportunidades de uso y aprovechamiento de estas tecnologías. Es lo que se ha denominado brecha digital en el doble aspecto de acceso y uso; no solo brecha tecnológica, sino –sobre todo– brecha del conocimiento. El Plan CEIBAL en Uruguay se propuso superar esta desigualdad y en apenas seis años disminuyó la brecha de acceso de manera contundente. En la actualidad, los sectores de menores ingresos tienen casi las mismas posibilidades de acceder a una computadora que los sectores más ricos. Antes del año 2007, la distancia era de 1 a 11, ahora es de 9 a 11. Es claro que esto no significa haber resuelto la brecha digital concebida integralmente (acceso, uso, aprovechamiento), pero es el punto de partida indispensable. El Plan CEIBAL es un comienzo, no un fin. Es el comienzo para generar igualdad de oportunidades y el principio de una transformación educativa a través del uso de las tecnologías. El comienzo para lograr una mayor igualdad en el acceso, aprovechamiento y en la generación de oportunidades para la creación de conocimiento

La rivalutazione della tecnica di coibentazione a insufflaggio a seguito del decreto requisiti minimi degli edifici

Viene presentato il risultato dello studio condotto dagli autori sull\u2019 influenza dei ponti termici nel caso di utilizzo della tecnica di coibentazione ad insufflaggio e delle possibili soluzioni di correzione in conformit\ue0 delle nuove disposizioni di legge del decreto requisiti minimi

Functional Roles and Therapeutic Applications of Exosomes in Hepatocellular Carcinoma

Exosomes are important in intercellular communication. They assure the horizontal transfer of specific functional contents (i.e., proteins, lipids, RNA molecules, and circulating DNA) from donor to recipient cells. Notably, tumor-derived exosomes (TDEs) appear to be an important vehicle of specific signals in cancer, impacting on tumor growth and metastasis. Recent researches point to the characterization of exosomes in Hepatocellular Carcinoma (HCC), the major adult liver malignancy. In this review, we summarize current findings on HCC exosomes, focusing on the identification of noncoding RNAs as exosome-enriched functional regulators and new potential biomarkers. The great potential of exosomes in future HCC diagnostic and therapeutic approaches is underlined