123 research outputs found

    Oxidative stress causes ERK phosphorylation and cell death in cultured retinal pigment epithelium: Prevention of cell death by AG126 and 15-deoxy-delta 12, 14-PGJ(2)

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    BACKGROUND: The retina, which is exposed to both sunlight and very high levels of oxygen, is exceptionally rich in polyunsaturated fatty acids, which makes it a favorable environment for the generation of reactive oxygen species. The cytotoxic effects of hydrogen peroxide (H(2)O(2)) induced oxidative stress on retinal pigment epithelium were characterized in this study. METHODS: The MTT cell viability assay, Texas-Red phalloidin staining, immunohistochemistry and Western blot analysis were used to assess the effects of oxidative stress on primary human retinal pigment epithelial cell cultures and the ARPE-19 cell line. RESULTS: The treatment of retinal pigment epithelial cells with H(2)O(2 )caused a dose-dependent decrease of cellular viability, which was preceded by a significant cytoskeletal rearrangement, activation of the Extracellular signal-Regulated Kinase, lipid peroxidation and nuclear condensation. This cell death was prevented partially by the prostaglandin derivative, 15d-PGJ(2 )and by the protein kinase inhibitor, AG126. CONCLUSION: 15d-PGJ(2 )and AG126 may be useful pharmacological tools in the future capable of preventing oxidative stress induced RPE cell death in human ocular diseases

    Magnesium Limitation Is an Environmental Trigger of the Pseudomonas aeruginosa Biofilm Lifestyle

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    Biofilm formation is a conserved strategy for long-term bacterial survival in nature and during infections. Biofilms are multicellular aggregates of cells enmeshed in an extracellular matrix. The RetS, GacS and LadS sensors control the switch from a planktonic to a biofilm mode of growth in Pseudomonas aeruginosa. Here we detail our approach to identify environmental triggers of biofilm formation by investigating environmental conditions that repress expression of the biofilm repressor RetS. Mg2+ limitation repressed the expression of retS leading to increased aggregation, exopolysaccharide (EPS) production and biofilm formation. Repression of retS expression under Mg2+ limitation corresponded with induced expression of the GacA-controlled small regulatory RNAs rsmZ and rsmY and the EPS biosynthesis operons pel and psl. We recently demonstrated that extracellular DNA sequesters Mg2+ cations and activates the cation-sensing PhoPQ two-component system, which leads to increased antimicrobial peptide resistance in biofilms. Here we show that exogenous DNA and EDTA, through their ability to chelate Mg2+, promoted biofilm formation. The repression of retS in low Mg2+ was directly controlled by PhoPQ. PhoP also directly controlled expression of rsmZ but not rsmY suggesting that PhoPQ controls the equilibrium of the small regulatory RNAs and thus fine-tunes the expression of genes in the RetS pathway. In summary, Mg2+ limitation is a biologically relevant environmental condition and the first bonafide environmental signal identified that results in transcriptional repression of retS and promotes P. aeruginosa biofilm formation

    Kaposin-B Enhances the PROX1 mRNA Stability during Lymphatic Reprogramming of Vascular Endothelial Cells by Kaposi's Sarcoma Herpes Virus

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    Kaposi's sarcoma (KS) is the most common cancer among HIV-positive patients. Histogenetic origin of KS has long been elusive due to a mixed expression of both blood and lymphatic endothelial markers in KS tumor cells. However, we and others discovered that Kaposi's sarcoma herpes virus (KSHV) induces lymphatic reprogramming of blood vascular endothelial cells by upregulating PROX1, which functions as the master regulator for lymphatic endothelial differentiation. Here, we demonstrate that the KSHV latent gene kaposin-B enhances the PROX1 mRNA stability and plays an important role in KSHV-mediated PROX1 upregulation. We found that PROX1 mRNA contains a canonical AU-rich element (ARE) in its 3′-untranslated region that promotes PROX1 mRNA turnover and that kaposin-B stimulates cytoplasmic accumulation of the ARE-binding protein HuR through activation of the p38/MK2 pathway. Moreover, HuR binds to and stabilizes PROX1 mRNA through its ARE and is necessary for KSHV-mediated PROX1 mRNA stabilization. Together, our study demonstrates that kaposin-B plays a key role in PROX1 upregulation during lymphatic reprogramming of blood vascular endothelial cells by KSHV

    Using Shifts in Amino Acid Frequency and Substitution Rate to Identify Latent Structural Characters in Base-Excision Repair Enzymes

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    Protein evolution includes the birth and death of structural motifs. For example, a zinc finger or a salt bridge may be present in some, but not all, members of a protein family. We propose that such transitions are manifest in sequence phylogenies as concerted shifts in substitution rates of amino acids that are neighbors in a representative structure. First, we identified rate shifts in a quartet from the Fpg/Nei family of base excision repair enzymes using a method developed by Xun Gu and coworkers. We found the shifts to be spatially correlated, more precisely, associated with a flexible loop involved in bacterial Fpg substrate specificity. Consistent with our result, sequences and structures provide convincing evidence that this loop plays a very different role in other family members. Second, then, we developed a method for identifying latent protein structural characters (LSC) given a set of homologous sequences based on Gu's method and proximity in a high-resolution structure. Third, we identified LSC and assigned states of LSC to clades within the Fpg/Nei family of base excision repair enzymes. We describe seven LSC; an accompanying Proteopedia page (http://proteopedia.org/wiki/index.php/Fpg_Nei_Protein_Family) describes these in greater detail and facilitates 3D viewing. The LSC we found provided a surprisingly complete picture of the interaction of the protein with the DNA capturing familiar examples, such as a Zn finger, as well as more subtle interactions. Their preponderance is consistent with an important role as phylogenetic characters. Phylogenetic inference based on LSC provided convincing evidence of independent losses of Zn fingers. Structural motifs may serve as important phylogenetic characters and modeling transitions involving structural motifs may provide a much deeper understanding of protein evolution

    Cellular distribution of vascular endothelial growth factor A (VEGFA) and B (VEGFB) and VEGF receptors 1 and 2 in focal cortical dysplasia type IIB

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    Members of the vascular endothelial growth factor (VEGF) family are key signaling proteins in the induction and regulation of angiogenesis, both during development and in pathological conditions. However, signaling mediated through VEGF family proteins and their receptors has recently been shown to have direct effects on neurons and glial cells. In the present study, we immunocytochemically investigated the expression and cellular distribution of VEGFA, VEGFB, and their associated receptors (VEGFR-1 and VEGFR-2) in focal cortical dysplasia (FCD) type IIB from patients with medically intractable epilepsy. Histologically normal temporal cortex and perilesional regions displayed neuronal immunoreactivity (IR) for VEGFA, VEGFB, and VEGF receptors (VEGFR-1 and VEGFR-2), mainly in pyramidal neurons. Weak IR was observed in blood vessels and there was no notable glial IR within the grey and white matter. In all FCD specimens, VEGFA, VEGFB, and both VEGF receptors were highly expressed in dysplastic neurons. IR in astroglial and balloon cells was observed for VEGFA and its receptors. VEGFR-1 displayed strong endothelial staining in FCD. Double-labeling also showed expression of VEGFA, VEGFB and VEGFR-1 in cells of the microglia/macrophage lineage. The neuronal expression of both VEGFA and VEGFB, together with their specific receptors in FCD, suggests autocrine/paracrine effects on dysplastic neurons. These autocrine/paracrine effects could play a role in the development of FCD, preventing the death of abnormal neuronal cells. In addition, the expression of VEGFA and its receptors in glial cells within the dysplastic cortex indicates that VEGF-mediated signaling could contribute to astroglial activation and associated inflammatory reactions

    Candidiasis, Bacterial Vaginosis, Trichomoniasis and Other Vaginal Conditions Affecting the Vulva

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    First measurement of neutrino oscillation parameters using neutrinos and antineutrinos by NOvA

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    The NOvA experiment has seen a 4.4σ signal of ν̄e appearance in a 2 GeV ν̄μ beam at a distance of 810 km. Using 12.33×1020 protons on target delivered to the Fermilab NuMI neutrino beamline, the experiment recorded 27 ν̄μ→ν̄e candidates with a background of 10.3 and 102 ν̄μ→ν̄μ candidates. This new antineutrino data are combined with neutrino data to measure the parameters |Δm322|=2.48-0.06+0.11×10-3 eV2/c4 and sin2θ23 in the ranges from (0.53-0.60) and (0.45-0.48) in the normal neutrino mass hierarchy. The data exclude most values near δCP=π/2 for the inverted mass hierarchy by more than 3σ and favor the normal neutrino mass hierarchy by 1.9σ and θ23 values in the upper octant by 1.6σ

    First international consensus on the methodology of lymphangiogenesis quantification in solid human tumours

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    The lymphatic system is the primary pathway of metastasis for most human cancers. Recent research efforts in studying lymphangiogenesis have suggested the existence of a relationship between lymphatic vessel density and patient survival. However, current methodology of lymphangiogenesis quantification is still characterised by high intra- and interobserver variability. For the amount of lymphatic vessels in a tumour to be a clinically useful parameter, a reliable quantification technique needs to be developed. With this consensus report, we therefore would like to initiate discussion on the standardisation of the immunohistochemical method for lymphangiogenesis assessment

    First measurement of neutrino oscillation parameters using neutrinos and antineutrinos by NOvA

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    The NOvA experiment has seen a 4.4 σ signal of ¯ ν e appearance in a 2 GeV ¯ ν μ beam at a distance of 810 km. Using 12.33 × 10 20 protons on target delivered to the Fermilab NuMI neutrino beamline, the experiment recorded 27 ¯ ν μ → ¯ ν e candidates with a background of 10.3 and 102 ¯ ν μ → ¯ ν μ candidates. This new antineutrino data are combined with neutrino data to measure the parameters | Δ m 2 32 | = 2.4 8 + 0.11 − 0.06 × 10 − 3     eV 2 / c 4 and sin 2 θ 23 in the ranges from (0.53–0.60) and (0.45–0.48) in the normal neutrino mass hierarchy. The data exclude most values near δ C P = π / 2 for the inverted mass hierarchy by more than 3 σ and favor the normal neutrino mass hierarchy by 1.9 σ and θ 23 values in the upper octant by 1.6 σ
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