RNA editing of the GLI1 transcription factor modulates the output of Hedgehog signaling

The Hedgehog (HH) signaling pathway has important roles in tumorigenesis and in embryonal patterning. The Gliomaassociated oncogene 1 (GLI1) is a key molecule in HH signaling, acting as a transcriptional effector and, moreover, is considered to be a potential therapeutic target for several types of cancer. To extend our previous focus on the implications of alternative splicing for HH signal transduction, we now report on an additional post-transcriptional mechanism with an impact on GLI1 activity, namely RNA editing. The GLI1 mRNA is highly edited at nucleotide 2179 by adenosine deamination in normal cerebellum, but the extent of this modification is reduced in cell lines from the cerebellar tumor medulloblastoma. Additionally, basal cell carcinoma tumor samples exhibit decreased GLI1 editing compared with normal skin. Interestingly, knocking down of either ADAR1 or ADAR2 reduces RNA editing of GLI1. This adenosine to inosine substitution leads to a change from Arginine to Glycine at position 701 that influences not only GLI1 transcriptional activity, but also GLI1-dependent cellular proliferation. Specifically, the edited GLI1, GLI1-701G, has a higher capacity to activate most of the transcriptional targets tested and is less susceptible to inhibition by the negative regulator of HH signaling suppressor of fused. However, the Dyrk1a kinase, implicated in cellular proliferation, is more effective in increasing the transcriptional activity of the non-edited GLI1. Finally, introduction of GLI1-701G into medulloblastoma cells confers a smaller increase in cellular growth relative to GLI1. In conclusion, our findings indicate that RNA editing of GLI1 is a regulatory mechanism that modulates the output of the HH signaling pathway. Copyright © 2013 Landes Bioscience

LC-MS metabolomics of psoriasis patients reveals disease severity-dependent increases in circulating amino acids that are ameliorated by anti-TNFα treatment

Psoriasis is an immune-mediated highly heterogeneous skin disease in which genetic as well as environmental factors play important roles. In spite of the local manifestations of the disease, psoriasis may progress to affect organs deeper than the skin. These effects are documented by epidemiological studies, but they are not yet mechanistically understood. In order to provide insight into the systemic effects of psoriasis, we performed a nontargeted high-resolution LC-MS metabolomics analysis to measure plasma metabolites from individuals with mild or severe psoriasis as well as healthy controls. Additionally, the effects of the anti-TNFα drug Etanercept on metabolic profiles were investigated in patients with severe psoriasis. Our analyses identified significant psoriasis-associated perturbations in three metabolic pathways: (1) arginine and proline, (2) glycine, serine and threonine, and (3) alanine, aspartate, and glutamate. Etanercept treatment reversed the majority of psoriasis-associated trends in circulating metabolites, shifting the metabolic phenotypes of severe psoriasis toward that of healthy controls. Circulating metabolite levels pre- and post-Etanercept treatment correlated with psoriasis area and severity index (PASI) clinical scoring (R(2) = 0.80; p < 0.0001). Although the responsible mechanism(s) are unclear, these results suggest that psoriasis severity-associated metabolic perturbations may stem from increased demand for collagen synthesis and keratinocyte hyperproliferation or potentially the incidence of cachexia. Data suggest that levels of circulating amino acids are useful for monitoring both the severity of disease as well as therapeutic response to anti-TNFα treatment

Untersuchung von Katalysatoren auf Gold/TiO2-Basis und optoelektronischen Halbleitern mittels Transmissionselektronenmikroskopie und Tomographie

Gold, usually known for its inertness, can be prepared as a nanoporous bulk material showing catalytic properties. A particular advantage of this catalytic material is the stable monolithic structure, combining mechanical strength, thermal and electrical conductivity and a reproducible porosity due to self-organization during the preparation. Important structural properties are the pore size and the size of the gold ligaments. TEM (transmission electron microscopy) is a powerful tool to obtain information on these properties. Additionally, the functionalization of the nanoporous gold with TiO2 particles was investigated. For the application in catalysis of CO-oxidation, the gold can be coated with TiO2 in order to enhance catalytic activity. Furthermore semiconductor heterostructures were investigated. II-VI-based microcavities grown by molecular beam epitaxy designed for emission in the blue spectral region have been comprehensively characterized by transmission electron microscopy in bright field, dark field and scanning mode. Moreover the STEM signal for InP based semiconductors was simulated

Structural characterization of an all-aminosugar-containing capsular polysaccharide from Colwellia psychrerythraea 34H

Colwellia psychrerythraea strain 34H, a Gram-negative bacterium isolated from Arctic marine sediments, is considered a model to study the adaptation to cold environments. Recently, we demonstrated that C. psychrerythraea 34H produces two different extracellular polysaccharides, a capsular polysaccharide and a medium released polysaccharide, which confer cryoprotection to the bacterium. In this study, we report the structure of an additional capsular polysaccharide produced by Colwellia grown at a different temperature. The structure was determined using chemical methods, and one- and two-dimensional NMR spectroscopy. The results showed a trisaccharide repeating unit made up of only amino-sugar residues: N-acetyl-galactosamine, 2,4-diacetamido-2,4,6-trideoxy-glucose (bacillosamine), and 2-acetamido-2-deoxyglucuronic acid with the following structure: →4)-β-d-GlcpNAcA-(1 →3)-β-d-QuipNAc4NAc-(1 →3)-β-d-GalpNAc-(1 →. The 3D model, generated in accordance with 1H,1H-NOE NMR correlations and consisting of ten repeating units, shows a helical structure. In contrast with the other extracellular polysaccharides produced from Colwellia at 4 °C, this molecule displays only a low ice recrystallization inhibition activity

Genomic insertion of a heterologous acetyltransferase generates a new lipopolysaccharide antigenic structure in brucella abortus and brucella melitensis

Brucellosis is a bacterial zoonosis of worldwide distribution caused by bacteria of the genus Brucella. In Brucella abortus and Brucella melitensis, the major species infecting domestic ruminants, the smooth lipopolysaccharide (S-LPS) is a virulence factor. This S-LPS carries a N-formyl-perosamine homopolymer O-polysaccharide that is the major antigen in serodiagnostic tests and is required for virulence. We report that the Brucella O-PS can be structurally and antigenically modified using wbdR, the acetyl-transferase gene involved in N-acetyl-perosamine synthesis in Escherichia coli O157:H7. Brucella constructs carrying plasmidic wbdR expressed a modified O-polysaccharide but were unstable, a problem circumvented by inserting wbdR into a neutral site of chromosome II. As compared to wild-type bacteria, both kinds of wbdR constructs expressed shorter O-polysaccharides and NMR analyses showed that they contained both N-formyl and N-acetyl-perosamine. Moreover, deletion of the Brucella formyltransferase gene wbkC in wbdR constructs generated bacteria producing only N-acetyl-perosamine homopolymers, proving that wbdR can replace for wbkC. Absorption experiments with immune sera revealed that the wbdR constructs triggered antibodies to new immunogenic epitope(s) and the use of monoclonal antibodies proved that B. abortus and B. melitensis wbdR constructs respectively lacked the A or M epitopes, and the absence of the C epitope in both backgrounds. The wbdR constructs showed resistance to polycations similar to that of the wild-type strains but displayed increased sensitivity to normal serum similar to that of a per R mutant. In mice, the wbdR constructs produced chronic infections and triggered antibody responses that can be differentiated from those evoked by the wild-type strain in S-LPS ELISAs. These results open the possibilities of developing brucellosis vaccines that are both antigenically tagged and lack the diagnostic epitopes of virulent field strains, thereby solving the diagnostic interference created by current vaccines against Brucella

HLA-Cw*0602 associates with a twofold higher prevalence of positive streptococcal throat swab at the onset of psoriasis: a case control study

<p>Abstract</p> <p>Background</p> <p>The influence of streptococcal infections in the pathogenesis of psoriasis is not yet understood. <it>In vitro </it>data suggest that streptococcal factors influence T-cell function in psoriasis in a HLA-dependent manner, but studies designed to measure the HLA-C/Streptococci interaction are lacking. In the present study, we hypothesized that there is a statistical interaction between the result of streptococcal throat cultures and the presence of the HLA-Cw*0602 allele in psoriasis patients.</p> <p>Methods</p> <p>We performed a case control study using the "Stockholm Psoriasis Cohort" consisting of patients consecutively recruited within 12 months of disease onset (Plaque psoriasis = 439, Guttate psoriasis = 143), matched to healthy controls (n = 454) randomly chosen from the Swedish Population Registry. All individuals underwent physical examination including throat swabs and DNA isolation for HLA-Cw*0602 genotyping.</p> <p>The prevalence of positive streptococcal throat swabs and HLA-Cw*0602 was compared between patients and controls and expressed as odds ratios with 95% confidence intervals. Associations were evaluated separately for guttate and plaque psoriasis by Fisher's exact test.</p> <p>Results</p> <p>Regardless of disease phenotype, the prevalence of positive streptococcal throat swabs in HLA-Cw*0602 positive patients was twice the prevalence among HLA-Cw*0602 negative patients (OR = 5.8 C.I. = 3.57–9.67, p < 0.001), while no difference was observed among Cw*0602 positive versus negative controls.</p> <p>The corresponding odds ratios for the guttate and plaque psoriasis phenotypes were 3.5 (CI = 1.5–8.7, p = 0.01) and 2.3 (CI = 1.0–5.1, p = 0.02) respectively.</p> <p>Conclusion</p> <p>These findings suggest that among HLA-Cw*0602 positive psoriasis patients, streptococci may contribute to the onset or exacerbation of the inflammatory process independent of the disease phenotype. However, studies on the functional interaction between HLA-C and streptococcal factors are needed.</p