Differential involvement of peroxisome-proliferator-activated receptors alpha and delta in fibrate and fatty-acid-mediated inductions of the gene encoding liver fatty-acid-binding protein in the liver and the small intestine.

Liver fatty-acid-binding protein (L-FABP) is a cytoplasmic polypeptide that binds with strong affinity especially to long-chain fatty acids (LCFAs). It is highly expressed in both the liver and small intestine, where it is thought to have an essential role in the control of the cellular fatty acid (FA) flux. Because expression of the gene encoding L-FABP is increased by both fibrate hypolipidaemic drugs and LCFAs, it seems to be under the control of transcription factors, termed peroxisome-proliferator-activated receptors (PPARs), activated by fibrate or FAs. However, the precise molecular mechanism by which these regulations take place remain to be fully substantiated. Using transfection assays, we found that the different PPAR subtypes (alpha, gamma and delta) are able to mediate the up-regulation by FAs of the gene encoding L-FABP in vitro. Through analysis of LCFA- and fibrate-mediated effects on L-FABP mRNA levels in wild-type and PPARalpha-null mice, we have found that PPARalpha in the intestine does not constitute a dominant regulator of L-FABP gene expression, in contrast with what is known in the liver. Only the PPARdelta/alpha agonist GW2433 is able to up-regulate the gene encoding L-FABP in the intestine of PPARalpha-null mice. These findings demonstrate that PPARdelta can act as a fibrate/FA-activated receptor in tissues in which it is highly expressed and that L-FABP is a PPARdelta target gene in the small intestine. We propose that PPARdelta contributes to metabolic adaptation of the small intestine to changes in the lipid content of the diet.

Gestión de recursos en nodos multi-core de memoria compartida

La gestión de recursos en los procesadores multi-core ha ganado importancia con la evolución de las aplicaciones y arquitecturas. Pero esta gestión es muy compleja. Por ejemplo, una misma aplicación paralela ejecutada múltiples veces con los mismos datos de entrada, en un único nodo multi-core, puede tener tiempos de ejecución muy variables. Hay múltiples factores hardware y software que afectan al rendimiento. La forma en que los recursos hardware (cómputo y memoria) se asignan a los procesos o threads, posiblemente de varias aplicaciones que compiten entre sí, es fundamental para determinar este rendimiento. La diferencia entre hacer la asignación de recursos sin conocer la verdadera necesidad de la aplicación, frente a asignación con una meta específica es cada vez mayor. La mejor manera de realizar esta asignación és automáticamente, con una mínima intervención del programador. Es importante destacar, que la forma en que la aplicación se ejecuta en una arquitectura no necesariamente es la más adecuada, y esta situación puede mejorarse a través de la gestión adecuada de los recursos disponibles. Una apropiada gestión de recursos puede ofrecer ventajas tanto al desarrollador de las aplicaciones, como al entorno informático donde ésta se ejecuta, permitiendo un mayor número de aplicaciones en ejecución con la misma cantidad de recursos. Así mismo, esta gestión de recursos no requeriría introducir cambios a la aplicación, o a su estrategia operativa. A fin de proponer políticas para la gestión de los recursos, se analizó el comportamiento de aplicaciones intensivas de cómputo e intensivas de memoria. Este análisis se llevó a cabo a través del estudio de los parámetros de ubicación entre los cores, la necesidad de usar la memoria compartida, el tamaño de la carga de entrada, la distribución de los datos dentro del procesador y la granularidad de trabajo. Nuestro objetivo es identificar cómo estos parámetros influyen en la eficiencia de la ejecución, identificar cuellos de botella y proponer posibles mejoras. Otra propuesta es adaptar las estrategias ya utilizadas por el Scheduler con el fin de obtener mejores resultados.

Biased V beta usage in immature thymocytes is independent of DJ beta proximity and pT alpha pairing.

During thymus development, the TCR beta locus rearranges before the TCR alpha locus. Pairing of productively rearranged TCR beta-chains with an invariant pT alpha chain leads to the formation of a pre-TCR and subsequent expansion of immature pre-T cells. Essentially nothing is known about the TCR V beta repertoire in pre-T cells before or after the expression of a pre-TCR. Using intracellular staining, we show here that the TCR V beta repertoire is significantly biased at the earliest developmental stage in which VDJ beta rearrangement has occurred. Moreover (and in contrast to the V(H) repertoire in immature B cells), V beta repertoire biases in immature T cells do not reflect proximity of V beta gene segments to the DJ beta cluster, nor do they depend upon preferential V beta pairing with the pT alpha chain. We conclude that V gene repertoires in developing T and B cells are controlled by partially distinct mechanisms.

A critical role for the T cell receptor alpha-chain connecting peptide domain in positive selection of CD1-independent NKT cells.

Natural killer T (NKT) cells are a subset of mature alpha beta TCR(+) cells that co-express NK lineage markers. Whereas most NKT cells express a canonical Valpha14/Vbeta8.2 TCR and are selected by CD1d, a minority of NKT cells express a diverse TCR repertoire and develop independently of CD1d. Little is known about the selection requirements of CD1d-independent NKT cells. We show here that NKT cells develop in RAG-deficient mice expressing an MHC class II-restricted transgenic TCR (Valpha2/Vbeta8.1) but only under conditions that lead to negative selection of conventional T cells. Moreover development of NKT cells in these mice is absolutely dependent upon an intact TCR alpha-chain connecting peptide domain, which is required for positive selection of conventional T cells via recruitment of the ERK signaling pathway. Collectively our data demonstrate that NKT cells can develop as a result of high avidity TCR/MHC class II interactions and suggest that common signaling pathways are involved in the positive selection of CD1d-independent NKT cells and conventional T cells.

Entorno gráfico de configuración para el soft-core OpenRISC

Aquest projecte consisteix en la realització d'un entorn gràfic que serveixi per generar SoCs basats en el processador soft-core OpenRISC. Aquest entorn permetrà afegir diferents components de manera dinàmica a un repositori d’IPs, mostrar i sel·leccionar qualsevol component disponible dins d’aquest repositori, amb la finalitat d’unir-los al bus del sistema i fer-los accessibles al processador OpenRISC. L’entorn també mostrarà en tot moment com va evolucionant el nostre SoC, guardarà cadascún dels projectes que es realitzen amb aquest entorn i finalment permetrà generar el SoC dissenyat.

Cellular immune responses to HCV core increase and HCV RNA levels decrease during successful antiretroviral therapy.

BACKGROUND: Hepatitis C virus (HCV) infection is a major cause of morbidity in HIV infected individuals. Coinfection with HIV is associated with diminished HCV-specific immune responses and higher HCV RNA levels. AIMS: To investigate whether long-term combination antiretroviral therapy (cART) restores HCV-specific T cell responses and improves the control of HCV replication. METHODS: T cell responses were evaluated longitudinally in 80 HIV/HCV coinfected individuals by ex vivo interferon-gamma-ELISpot responses to HCV core peptides, that predominantly stimulate CD4(+) T cells. HCV RNA levels were assessed by real-time PCR in 114 individuals. RESULTS: The proportion of individuals with detectable T cell responses to HCV core peptides was 19% before starting cART, 24% in the first year on cART and increased significantly to 45% and 49% after 33 and 70 months on cART (p=0.001). HCV-specific immune responses increased in individuals with chronic (+31%) and spontaneously cleared HCV infection (+30%). Median HCV RNA levels before starting cART were 6.5 log(10) IU/ml. During long-term cART, median HCV-RNA levels slightly decreased compared to pre-cART levels (-0.3 log10 IU/ml, p=0.02). CONCLUSIONS: Successful cART is associated with increasing cellular immune responses to HCV core peptides and with a slight long-term decrease in HCV RNA levels. These findings are in line with the favourable clinical effects of cART on the natural history of hepatitis C and with the current recommendation to start cART earlier in HCV/HIV coinfected individuals.

Maladie de Behçet: d'Hippocrate aux antagonistes du TNF-alpha

Behçet's disease is a systemic vasculitis affecting small and large vessels (arteries, veins, veinules), characterized by recurrent oral ulcerations, genital ulcerations, inflammation of the eye and skin lesions. It can also involve articulations, central nervous system and gastro-intestinal tract. The etiology of this disease is still unknown, but the most largely discussed hypothesis is that of an important inflammatory response triggered by an infectious agent in a genetically susceptible host. The diagnostic is a based on clinical elements, because no specific diagnostic test exists. The treatment of Behçet's disease is depending on the clinical involvement and has been enlarged in recent years by TNF-alpha-blockers which constitute undoubtedly an important progress in the management of this complex disease.

Calpain hydrolysis of alpha- and beta2-adaptins decreases clathrin-dependent endocytosis and may promote neurodegeneration.

Clathrin-dependent endocytosis is mediated by a tightly regulated network of molecular interactions that provides essential protein-protein and protein-lipid binding activities. Here we report the hydrolysis of the alpha- and beta2-subunits of the tetrameric adaptor protein complex 2 by calpain. Calcium-dependent alpha- and beta2-adaptin hydrolysis was observed in several rat tissues, including brain and primary neuronal cultures. Neuronal alpha- and beta2-adaptin cleavage was inducible by glutamate stimulation and was accompanied by the decreased endocytosis of transferrin. Heterologous expression of truncated forms of the beta2-adaptin subunit significantly decreased the membrane recruitment of clathrin and inhibited clathrin-mediated receptor endocytosis. Moreover, the presence of truncated beta2-adaptin sensitized neurons to glutamate receptor-mediated excitotoxicity. Proteolysis of alpha- and beta2-adaptins, as well as the accessory clathrin adaptors epsin 1, adaptor protein 180, and the clathrin assembly lymphoid myeloid leukemia protein, was detected in brain tissues after experimentally induced ischemia and in cases of human Alzheimer disease. The present study further clarifies the central role of calpain in regulating clathrin-dependent endocytosis and provides evidence for a novel mechanism through which calpain activation may promote neurodegeneration: the sensitization of cells to glutamate-mediated excitotoxicity via the decreased internalization of surface receptors.

Truncation of the receptor carboxyl terminus impairs agonist-dependent phosphorylation and desensitization of the alpha 1B-adrenergic receptor.

The alpha 1B-adrenergic receptor (alpha 1BAR) and its truncated mutant T368 lacking the last 147 amino acids were stably expressed in Rat1 fibroblasts. The wild type alpha 1BAR was rapidly phosphorylated upon exposure to the agonist epinephrine as well as to phorbol ester as assessed by immunoprecipitation of the receptor with antiserum raised against its amino-terminal portion. Exposure of cells expressing the wild type alpha 1BAR to epinephrine resulted also in rapid homologous desensitization of receptor-mediated response on polyphosphoinositide hydrolysis. On the other hand, truncation of the serine- and threonine-rich carboxyl portion of the alpha 1BAR abolished agonist-induced phosphorylation and greatly impaired homologous desensitization of the receptor. The truncated receptor T368 could undergo agonist-induced decrease of cell surface receptors but to a lesser extent, as compared with the wild type alpha 1BAR. These results demonstrate that the carboxyl portion of the alpha 1BAR plays a crucial role in the regulation of receptor function. They also suggest a strong relationship between agonist-induced phosphorylation and desensitization of the alpha 1BAR, which were both insensitive to the inhibitor of protein kinase C RO-318220. Our findings support the emerging hypothesis that the biochemical mechanisms involved in rapid agonist-dependent regulation of G protein-coupled receptors, which activate polyphosphoinositide hydrolysis, do not primarily involve protein kinase C.

Rest/nrsf governs the expression of dense-core vesicle gliosecretion in astrocytes

Astrocytes are the brain nonnerve cells that are competent for gliosecretion, i.e., for expression and regulated exocytosis of clear and dense-core vesicles (DCVs). We investigated whether expression of astrocyte DCVs is governed by RE-1-silencing transcription factor (REST)/neuron-restrictive silencer factor, the transcription repressor that orchestrates nerve cell differentiation. Rat astrocyte cultures exhibited high levels of REST and expressed neither DCVs nor their markers (granins, peptides, and membrane proteins). Transfection of dominant-negative construct of REST induced the appearance of DCVs filled with secretogranin 2 and neuropeptide Y (NPY) and distinct from other organelles. Total internal reflection fluorescence analysis revealed NPY-monomeric red fluorescent protein-labeled DCVs to undergo Ca21 -dependent exocytosis, which was largely prevented by botulinum toxin B. In the I-II layers of the human temporal brain cortex, all neurons and microglia exhibited the expected inappreciable and high levels of REST, respectively. In contrast, astrocyte RESTwas variable, going from inappreciable to high, and accompanied by a variable expression of DCVs. In conclusion, astrocyte DCV expression and gliosecretion are governed by REST. The variable in situ REST levels may contribute to the wellknown structural/ functional heterogeneity of astrocytes.

Homer1a is a core brain molecular correlate of sleep loss.

Sleep is regulated by a homeostatic process that determines its need and by a circadian process that determines its timing. By using sleep deprivation and transcriptome profiling in inbred mouse strains, we show that genetic background affects susceptibility to sleep loss at the transcriptional level in a tissue-dependent manner. In the brain, Homer1a expression best reflects the response to sleep loss. Time-course gene expression analysis suggests that 2,032 brain transcripts are under circadian control. However, only 391 remain rhythmic when mice are sleep-deprived at four time points around the clock, suggesting that most diurnal changes in gene transcription are, in fact, sleep-wake-dependent. By generating a transgenic mouse line, we show that in Homer1-expressing cells specifically, apart from Homer1a, three other activity-induced genes (Ptgs2, Jph3, and Nptx2) are overexpressed after sleep loss. All four genes play a role in recovery from glutamate-induced neuronal hyperactivity. The consistent activation of Homer1a suggests a role for sleep in intracellular calcium homeostasis for protecting and recovering from the neuronal activation imposed by wakefulness.