947 resultados para MAMMALIAN TARGET OF RAPAMYCIN COMPLEX 1


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City Audit Report

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City Audit Report

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Fas(Apo-1/CD95), a receptor belonging to the tumor necrosis factor receptor family, induces apoptosis when triggered by Fas ligand. Upon its activation, the cytoplasmic domain of Fas binds several proteins which transmit the death signal. We used the yeast two-hybrid screen to isolate Fas-associated proteins. Here we report that the ubiquitin-conjugating enzyme UBC9 binds to Fas at the interface between the death domain and the membrane-proximal region of Fas. This interaction is also seen in vivo. UBC9 transiently expressed in HeLa cells bound to the co-expressed cytoplasmic segment of Fas. FAF1, a Fas-associated protein that potentiates apoptosis (Chu et al. (1996) Proc. Natl. Acad. Sci. USA 92, 11894-11898), was found to contain sequences similar to ubiquitin. These results suggest that proteins related to the ubiquitination pathway may modulate the Fas signaling pathway.

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Host genome studies are increasingly available for the study of infectious disease susceptibility. Current technologies include large-scale genotyping, genome-wide screens such as transcriptome and silencing (silencing RNA) studies, and increasingly, the possibility to sequence complete genomes. These approaches are of interest for the study of individuals who remain uninfected despite documented exposure to human immunodeficiency virus type 1. The main limitation remains the ascertainment of exposure and establishing large cohorts of informative individuals. The pattern of enrichment for CCR5 16;32 homozygosis should serve as the standard for assessing the extent to which a given cohort (of white subjects) includes a large proportion of exposed uninfected individuals.

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We present a method to compute, quickly and efficiently, the mutual information achieved by an IID (independent identically distributed) complex Gaussian signal on a block Rayleigh-faded channel without side information at the receiver. The method accommodates both scalar and MIMO (multiple-input multiple-output) settings. Operationally, this mutual information represents the highest spectral efficiency that can be attained using Gaussiancodebooks. Examples are provided that illustrate the loss in spectral efficiency caused by fast fading and how that loss is amplified when multiple transmit antennas are used. These examples are further enriched by comparisons with the channel capacity under perfect channel-state information at the receiver, and with the spectral efficiency attained by pilot-based transmission.

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The adrenergic receptors (ARs) belong to the superfamily of membrane-bound G protein coupled receptors (GPCRs). Our investigation has focused on the structure-function relationship of the alpha 1b-AR subtype used as the model system for other GPCRs. Site-directed mutagenesis studies have elucidated the structural domains of the alpha 1b-AR involved in ligand binding, G protein coupling or desensitization. In addition, a combined approach using site-directed mutagenesis and molecular dynamics analysis of the alpha 1b-AR has provided information about the potential mechanisms underlying the activation process of the receptor, i.e. its transition from the 'inactive' to the 'active' conformation.

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BACKGROUND AND PROCEDURE: To determine the possible role of Fas/FasL system in the particularly heterogeneous behaviour of neuroblastoma (NB), we have measured the functional expression of Fas and its ligand, FasL, in primary neuroblastoma samples and cell lines by immunohistochemistry and flow cytometry. RESULTS: Our results reveal that while Fas expression is associated with low stage and more mature tumors, heterogeneous FasL expression was mostly detected in high stage tumors, with our apparent correlation to MYCN amplification. Flow cytometric analysis of cell lines demonstrated a high expression of Fas in epithelial-type, HLA class I positive cell lines, which was lost upon activation with phorbol esters. In contrast, Fas ligand was detected in only a small subset of cell lines. CONCLUSIONS: In some cell lines, cytotoxic assays revealed the ability of NB-associated Fas receptor to transduce an apoptotic signal upon triggering. The pattern of functional Fas/FasL expression in tumours and cell lines suggests that this system may be involved in the evasion of highly malignant neuroblastoma cells to host immune response.

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Many complex systems may be described by not one but a number of complex networks mapped on each other in a multi-layer structure. Because of the interactions and dependencies between these layers, the state of a single layer does not necessarily reflect well the state of the entire system. In this paper we study the robustness of five examples of two-layer complex systems: three real-life data sets in the fields of communication (the Internet), transportation (the European railway system), and biology (the human brain), and two models based on random graphs. In order to cover the whole range of features specific to these systems, we focus on two extreme policies of system's response to failures, no rerouting and full rerouting. Our main finding is that multi-layer systems are much more vulnerable to errors and intentional attacks than they appear from a single layer perspective.

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Mutations in LACERATA (LCR), FIDDLEHEAD (FDH), and BODYGUARD (BDG) cause a complex developmental syndrome that is consistent with an important role for these Arabidopsis genes in cuticle biogenesis. The genesis of their pleiotropic phenotypes is, however, poorly understood. We provide evidence that neither distorted depositions of cutin, nor deficiencies in the chemical composition of cuticular lipids, account for these features, instead suggesting that the mutants alleviate the functional disorder of the cuticle by reinforcing their defenses. To better understand how plants adapt to these mutations, we performed a genome-wide gene expression analysis. We found that apparent compensatory transcriptional responses in these mutants involve the induction of wax, cutin, cell wall, and defense genes. To gain greater insight into the mechanism by which cuticular mutations trigger this response in the plants, we performed an overlap meta-analysis, which is termed MASTA (MicroArray overlap Search Tool and Analysis), of differentially expressed genes. This suggested that different cell integrity pathways are recruited in cesA cellulose synthase and cuticular mutants. Using MASTA for an in silico suppressor/enhancer screen, we identified SERRATE (SE), which encodes a protein of RNA-processing multi-protein complexes, as a likely enhancer. In confirmation of this notion, the se lcr and se bdg double mutants eradicate severe leaf deformations as well as the organ fusions that are typical of lcr and bdg and other cuticular mutants. Also, lcr does not confer resistance to Botrytis cinerea in a se mutant background. We propose that there is a role for SERRATE-mediated RNA signaling in the cuticle integrity pathway.

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Cpl-1, a pneumococcal phage lytic enzyme, was tested in rats with experimental endocarditis due to Streptococcus pneumoniae WB4. High-dose regimen Cpl-1 eliminated pneumococci from blood within 30 min and decreased bacterial titers in vegetations (>4 log10 CFU/g) within 2 h. Rapid bacterial lysis induced by Cpl-1 treatment increased cytokine secretion noticeably.

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Cannabinoid receptor 1 (CB(1) receptor) controls several neuronal functions, including neurotransmitter release, synaptic plasticity, gene expression and neuronal viability. Downregulation of CB(1) expression in the basal ganglia of patients with Huntington's disease (HD) and animal models represents one of the earliest molecular events induced by mutant huntingtin (mHtt). This early disruption of neuronal CB(1) signaling is thought to contribute to HD symptoms and neurodegeneration. Here we determined whether CB(1) downregulation measured in patients with HD and mouse models was ubiquitous or restricted to specific striatal neuronal subpopulations. Using unbiased semi-quantitative immunohistochemistry, we confirmed previous studies showing that CB(1) expression is downregulated in medium spiny neurons of the indirect pathway, and found that CB(1) is also downregulated in neuropeptide Y (NPY)/neuronal nitric oxide synthase (nNOS)-expressing interneurons while remaining unchanged in parvalbumin- and calretinin-expressing interneurons. CB(1) downregulation in striatal NPY/nNOS-expressing interneurons occurs in R6/2 mice, Hdh(Q150/Q150) mice and the caudate nucleus of patients with HD. In R6/2 mice, CB(1) downregulation in NPY/nNOS-expressing interneurons correlates with diffuse expression of mHtt in the soma. This downregulation also occludes the ability of cannabinoid agonists to activate the pro-survival signaling molecule cAMP response element-binding protein in NPY/nNOS-expressing interneurons. Loss of CB(1) signaling in NPY/nNOS-expressing interneurons could contribute to the impairment of basal ganglia functions linked to HD.

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MHC-peptide tetramers have become essential tools for T-cell analysis, but few MHC class II tetramers incorporating peptides from human tumor and self-antigens have been developed. Among limiting factors are the high polymorphism of class II molecules and the low binding capacity of the peptides. Here, we report the generation of molecularly defined tetramers using His-tagged peptides and isolation of folded MHC/peptide monomers by affinity purification. Using this strategy we generated tetramers of DR52b (DRB3*0202), an allele expressed by approximately half of Caucasians, incorporating an epitope from the tumor antigen NY-ESO-1. Molecularly defined tetramers avidly and stably bound to specific CD4(+) T cells with negligible background on nonspecific cells. Using molecularly defined DR52b/NY-ESO-1 tetramers, we could demonstrate that in DR52b(+) cancer patients immunized with a recombinant NY-ESO-1 vaccine, vaccine-induced tetramer-positive cells represent ex vivo in average 1:5,000 circulating CD4(+) T cells, include central and transitional memory polyfunctional populations, and do not include CD4(+)CD25(+)CD127(-) regulatory T cells. This approach may significantly accelerate the development of reliable MHC class II tetramers to monitor immune responses to tumor and self-antigens.