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See detailMelting trends over the Greenland ice sheet (1958–2009) from spaceborne microwave data and regional climate models
Fettweis, Xavier ULg; Tedesco, Marco; van den Broeke, Michiel et al

in The Cryosphere [=TC] (2011), 5

To study near-surface melt changes over the Greenland ice sheet (GrIS) since 1979, melt extent estimates from two regional climate models were compared with those obtained from spaceborne microwave ... [more ▼]

To study near-surface melt changes over the Greenland ice sheet (GrIS) since 1979, melt extent estimates from two regional climate models were compared with those obtained from spaceborne microwave brightness temperatures using two different remote sensing algorithms. The results from the two models were consistent with those obtained with the remote sensing algorithms at both daily and yearly time scales, encouraging the use of the models for analyzing melting trends before the satellite era (1958–1979), when forcing data is available. Differences between satellite-derived and model-simulated results still occur and are used here to identify (i) biases in the snow models (notably in the albedo parametrization, in the thickness of a snow layer, in the maximum liquid water content within the snowpack and in the snowfall impacting the bare ice appearance in summer) and (ii) limitations in the use of passive microwave data for snowmelt detection at the edge of the ice sheet due to mixed pixel effect (e.g., tundra or rock nearby the ice sheet). The results from models and spaceborne microwave sensors confirm a significant (p-value = 0.01) increase in GrIS surface melting since 1979. The melt extent recorded over the last years (1998, 2003, 2005 and 2007) is unprecedented in the last 50 yr with the cumulated melt area in the 2000's being, on the average, twice that of the 1980's. [less ▲]

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See detailMélusine et ses antécédents antiques
Pirenne-Delforge, Vinciane ULg

in Actes du XXIXe Congrès de l’Association des Professeurs de Langues Ancienens de l’Enseignement Supérieur (Montpellier, 31 mai - 1er juin 1996) (1997)

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See detailMemantine-induced brain activation as a model for the rapid screening of potential novel antipsychotic compounds: Exemplified by an mGlu2/3 receptor agonist
Dedeurwaerdere, S.; Wintmolders, C.; Straetemans, R. et al

in Society-for-Neuroscience Abstracts/Annual Meeting Publications (2010, November 17), 40

Schizophrenia is a severe, disabling chronic disorder affecting approximately 1% of the population. Unfortunately, patients afflicted by this difficult to treat psychiatric illness remain stigmatized and ... [more ▼]

Schizophrenia is a severe, disabling chronic disorder affecting approximately 1% of the population. Unfortunately, patients afflicted by this difficult to treat psychiatric illness remain stigmatized and are likely to suffer permanent cognitive and social deficits. Improvements and development of more robust and hopefully predictive screening assays for this disease should enhance the identification and development of novel treatments. The present study describes a rapid and robust method for the testing of potential novel antipsychotics by utilising a simplified [14C]2-deoxyglucose (2-DG) uptake autoradiography technique following memantine-induced brain activation. Male C57BL/6JCRL mice were treated with either vehicle, ketamine (30 mg/kg, s.c.) or memantine (20 mg/kg, s.c.). Both NMDA antagonists induced significant increases in 2-DG uptake in specific brain region such as lateral orbital cortex, olfactory tubercle, piriform cortex, cingulate cortex, retrosplenial cortex, lacunosum molecular layer of the hippocampus and the lateral posterior thalamic nucleus. Interestingly, memantine elicited a more robust brain activation signature with a larger dynamic window than ketamine. For further characterisation of the assay, we also tested the effect of diet (fasting versus non-fasting) and different vehicles. In addition, dedicated software, developed particularly for this assay, was evaluated for automated quantification of the brain sections. In subsequent reversal studies, we found that in accordance to the ketamine challenge model (Duncan et al. 1998), the “atypical” anti-psychotic clozapine (2.5 and 10 mg/kg, s.c.) significantly reversed memantine-induced 2-DG uptake whilst the “typical” anti-psychotic haloperidol (0.32 mg/kg, s.c.) was inactive thus further validating our choice of memantine for the challenge agent. An additional study then determined the effects of a mGlu2/3 receptor agonist on both ketamine and memantine-induced brain activation. Pre-treatment with LY404039 (10 mg/kg, s.c.) fully reversed both the ketamine and memantine-induced increase in 2-DG uptake without effects on basal 2-DG uptake. Finally, a small animal PET study was performed with [18F]-FDG in mice and rats investigating the effect of memantine (20 mg/kg) administration in vivo. This study confirmed the memantine-induced brain activation previously demonstrated by autoradiography. In conclusion, this novel pre-clinical method shows potential for the screening of compounds targeting the NMDA receptor hypofunction hypothesis of schizophrenia and may assist in translating these findings from the bench to clinic. [less ▲]

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See detailMembrane associated proteases and their inhibitors in tumour angiogenesis
Noël, Agnès ULg; Maillard, Catherine ULg; Rocks, Natacha ULg et al

in Journal of Clinical Pathology (2004), 57(6), 577-584

Cell surface proteolysis is an important mechanism for generating biologically active proteins that mediate a range of cellular functions and contribute to biological processes such as angiogenesis ... [more ▼]

Cell surface proteolysis is an important mechanism for generating biologically active proteins that mediate a range of cellular functions and contribute to biological processes such as angiogenesis. Although most studies have focused on the plasminogen system and matrix metalloproteinases ( MMPs), recently there has been an increase in the identification of membrane associated proteases, including serine proteases, ADAMs, and membrane-type MMPs (MT-MMPs). Normally, protease activity is tightly controlled by tissue inhibitors of MMPs (TIMPs) and plasminogen activator inhibitors (PAIs). The balance between active proteases and inhibitors is thought to determine the occurrence of proteolysis in vivo. High concentrations of proteolytic system components correlate with poor prognosis in many cancers. Paradoxically, high (not low) PAI-1 or TIMP concentrations predict poor survival in patients with various cancers. Recent observations indicate a much more complex role for protease inhibitors in tumour progression and angiogenesis than initially expected. As knowledge in the field of protease biology has improved, the unforeseen complexities of cell associated enzymes and their interaction with physiological inhibitors have emerged, often revealing unexpected mechanisms of action. [less ▲]

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See detailMembrane associated thiamin phosphatases in the electric organ of E. electricus
Michel-Cahay, C; Bettendorff, Lucien ULg; De Rycker, C et al

in Archives Internationales de Physiologie et de Biochimie (1985), 93

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See detailMembrane associated thiamine phosphatases in the electric organ of Electrophorus electricus
Michel-Cahay, C; Bettendorff, Lucien ULg; De Rycker, C et al

Poster (1985, September 03)

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See detailMembrane Destabilization Induced By Beta-Amyloid Peptide 29-42: Importance Of The Amino-Terminus
Mingeot-Leclercq, Mp.; Lins, Laurence ULg; Bensliman, M. et al

in Chemistry and Physics of Lipids (2002), 120(1-2), 57-74

Increasing evidence implicates interactions between Abeta-peptides and membrane lipids in Alzheimer's disease. To gain insight into the potential role of the free amino group of the N-terminus of Abeta29 ... [more ▼]

Increasing evidence implicates interactions between Abeta-peptides and membrane lipids in Alzheimer's disease. To gain insight into the potential role of the free amino group of the N-terminus of Abeta29-42 fragment in these processes, we have investigated the ability of Abeta29-42 unprotected and Abeta29-42 N-protected to interact with negatively-charged liposomes and have calculated the interaction with membrane lipids by conformational analysis. Using vesicles mimicking the composition of neuronal membranes, we show that both peptides have a similar capacity to induce membrane fusion and permeabilization. The fusogenic effect is related to the appearance of non-bilayer structures where isotropic motions occur as shown by 31P and 2H NMR studies. The molecular modeling calculations confirm the experimental observations and suggest that lipid destabilization could be due to the ability of both peptides to adopt metastable positions in the presence of lipids. In conclusion, the presence of a free or protected (acetylated) amino group in the N-terminus of Abeta29-42 is therefore probably not crucial for destabilizing properties of the C-terminal fragment of Abeta peptides. [less ▲]

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See detailLa membrane du globule gras du lait (MFGM) : une composition et une structure originale.
Bodson, Pascal; Vanderghem, Caroline ULg; Danthine, Sabine ULg et al

Poster (2008, January 23)

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See detailThe membrane form of the DNA repair protein Ku interacts at the cell surface with metalloproteinase 9.
Monferran, Sylvie; Paupert, Jenny ULg; Dauvillier, Stephanie et al

in The EMBO journal (2004), 23(19), 3758-68

The Ku heterodimer (Ku70/Ku80) plays a central role in DNA double-strand breaks repair. Ku is also expressed on the cell surface of different types of cells where its function remains poorly understood ... [more ▼]

The Ku heterodimer (Ku70/Ku80) plays a central role in DNA double-strand breaks repair. Ku is also expressed on the cell surface of different types of cells where its function remains poorly understood. From a yeast two-hybrid screen, we have identified a specific interaction between the core region of Ku80 and the hemopexin domain of metalloproteinase 9 (MMP-9), a key enzyme involved in the degradation of extracellular matrix (ECM) components. Ku associates with MMP-9 on the surface of leukemic cells as demonstrated by co-immunoprecipitation experiments in membrane extracts and double-label immunofluorescence studies. In normal and tumoral migratory cells, Ku80 and MMP-9 colocalize at the periphery of leading edge of cells and cellular invasion of collagen IV matrices was blocked by antibodies directed against Ku70 or Ku80 subunits as well as by Ku80-specific antisense oligonucleotides. Our results indicate that Ku and MMP-9 interact at the cell membrane of highly invasive hematopoietic cells of normal and tumoral origin and document the unexpected importance of the membrane-associated form of Ku in the regulation of ECM remodelling. [less ▲]

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See detailMembrane interactions of cyclic lipodepsipeptides from the viscosin group
Geudens, Niels; Feher, Krisztina; De Vleeschouwer et al

Poster (2014, June)

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See detailMembrane topology of the Escherichia coli AmpG permease required for recycling of cell wall anhydromuropeptides and AmpC beta-lactamase induction.
Chahboune, Aicha; Decaffmeyer, Marc; Brasseur, Robert ULg et al

in Antimicrobial Agents and Chemotherapy (2005), 49(3), 1145-9

Escherichia coli, and presumably most other gram-negative bacteria, possesses an efficient protein machinery for recycling its peptidoglycan during cell growth. The major recycled peptidoglycan product is ... [more ▼]

Escherichia coli, and presumably most other gram-negative bacteria, possesses an efficient protein machinery for recycling its peptidoglycan during cell growth. The major recycled peptidoglycan product is N-acetylglucosamine-1,6-anhydro-N-acetylmuramic acid-tetrapeptide. Its uptake from the periplasm into the cytoplasm is carried out via the AmpG protein, an intrinsic membrane protein. In gram-negative bacteria carrying an ampC beta-lactamase-inducible gene on their chromosomes, the induction mechanism is directly linked to peptidoglycan recycling. After identification of the different putative hydrophobic segments by computing, the AmpG topology was experimentally determined by using beta-lactamase fusion. In the proposed model, AmpG contains 10 transmembrane segments and two large cytoplasmic loops. [less ▲]

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See detailMembrane Topology, Structure, and Functions of the Penicillin-Interactive Proteins
Ghuysen, Jean-Marie ULg

in Biotechnology & Applied Biochemistry (1990, October), 12(5), 468-472

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See detailMembrane Translocation and Relationship with MHC Class I of a Human Thymic Neurophysin-Like Protein
Geenen, Vincent ULg; Vandersmissen, E.; Cormann-Goffin, N. et al

in Thymus (1993), 22(1), 55-66

Thymic epithelial and nurse cells (TEC/TNC) synthesize an oxytocin (OT)-like peptide in association with a neurophysin (NP)-related protein in a way similar to in the hypothalamo-neurohypophysial (NHP ... [more ▼]

Thymic epithelial and nurse cells (TEC/TNC) synthesize an oxytocin (OT)-like peptide in association with a neurophysin (NP)-related protein in a way similar to in the hypothalamo-neurohypophysial (NHP) system. The central T-cell tolerance of the NHP neuroendocrine functions have been proposed to be mediated through these thymic NHP-related peptides due to their close homology with the NHP neurohormones OT and vasopressin (VP). In order to investigate their putative presentation by proteins of the major histocompatibility complex (MHC), human thymic membranes were purified and passed through an immunoaffinity column using mAb B9.12 directed to the monomorphic determinant of human MHC class I proteins. This methodology provided the following observations: (1) a NP-like protein is translocated in human thymic membranes and is retained by B9.12 on the column; (2) the MW of this NP-like material (50-55 kD) is quite different from the MW of hypothalamic NP proteins (10 kD), and (3) this thymic NP-like protein could be identified on Western blots with mAb B9.12. The precise extent of this relationship between the thymic NP-like protein and the Ig/MHC superfamily is actually investigated through the characterization of the genetic mechanisms responsible for the thymic expression of NHP-related peptides. Given the physiological importance of OT and of its binding to NP for transport along the axonal processes of the NHP tract, we postulate that, somewhat analogously, the thymic NP-/MHC class I-related protein could be involved in the presentation of the OT-like peptide to immature T-cells. [less ▲]

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See detailMembrane type 1 matrix metalloproteinase detection in tumors, using the iodinated endogenous [123I]-tissue inhibitor 2 of metalloproteinases as imaging agent.
Van Steenkiste, Magali; Oltenfreiter, Ruth; Frankenne, Francis et al

in Cancer Biotherapy & Radiopharmaceuticals (2010), 25(5), 511-20

Matrix metalloproteinases (MMPs) are principal participants in tumor development. In addition to serve as a useful biochemical marker, MMP expression may also provide a target for the diagnostic in vivo ... [more ▼]

Matrix metalloproteinases (MMPs) are principal participants in tumor development. In addition to serve as a useful biochemical marker, MMP expression may also provide a target for the diagnostic in vivo imaging of tumors, using a radiolabeled inhibitor. This study investigates the use of membrane type 1 (MT1)-MMP as target for in vivo tumor diagnosis. Specific binding of the endogenous tissue inhibitor of metalloproteinase-2 (TIMP-2) to MT1-MMP has been previously described. In this study, biodistribution and imaging experiments were performed on MT1-MMP-overexpressing (S.1.5) and control (C.IV.3) tumor-inoculated mice using [(123)I]-recombinant human TIMP-2 (rhTIMP-2) as radioligand and [(123)I]-rhTIMP-1 as control. The expression profile was controlled in vitro and on tumor extracts. rhTIMP-2 as well as rhTIMP-1 were labeled using the Iodogen method and characterized. Biodistribution of [(123)I]-rhTIMP-2 showed a tumor uptake of 2.87% +/- 1.58% ID/g at 3 hours postinjection in S.1.5. Tumor values of [(123)I]-rhTIMP-1 and [(123)I]-rhTIMP-2 evaluated in S.1.5 and C.IV.3, respectively, were significantly lower. Planar imaging revealed significant uptake of [(123)I]-rhTIMP-2 in S.1.5 compared with contralateral background areas. This could not be observed in C.IV.3 and with [(123)I]-rhTIMP-1 in S.1.5. All tumors were well established (200-800 mg). These results suggest that rhTIMP-2 holds potential for development of radiotracers for in vivo imaging in overexpressing MT1-MMP but not in similar tumors that do not express this protease. [less ▲]

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See detailMembrane Type 1 Matrix Metalloproteinase-Associated Degradation of Tissue Inhibitor of Metalloproteinase 2 in Human Tumor Cell Lines
Maquoi, Erik ULg; Frankenne, Francis ULg; Baramova, Eugénia et al

in Journal of Biological Chemistry (2000), 275(15), 11368-78

Tissue inhibitor of metalloproteinase 2 (TIMP-2) is required for the membrane type 1 matrix metalloproteinase (MT1-MMP)-dependent activation of pro-MMP-2 on the cell surface. MT1-MMP-bound TIMP-2 has been ... [more ▼]

Tissue inhibitor of metalloproteinase 2 (TIMP-2) is required for the membrane type 1 matrix metalloproteinase (MT1-MMP)-dependent activation of pro-MMP-2 on the cell surface. MT1-MMP-bound TIMP-2 has been shown to function as a receptor for secreted pro-MMP-2, resulting in the formation of a trimolecular complex. In the presence of uncomplexed active MT1-MMP, the prodomain of cell surface-associated MMP-2 is cleaved, and activated MMP-2 is released. However, the behavior of MT1-MMP-bound TIMP-2 during MMP-2 activation is currently unknown. In this study, (125)I-labeled recombinant TIMP-2 ((125)I-rTIMP-2) was used to investigate the fate of TIMP-2 during pro-MMP-2 activation by HT1080 and transfected A2058 cells. HT1080 and A2058 cells transfected with MT1-MMP cDNA (but not vector-transfected A2058 cells) were able to bind (125)I-rTIMP-2, to activate pro-MMP-2, and to process MT1-MMP into an inactive 43-kDa form. Under these conditions, (125)I-rTIMP-2 bound to the cell surface was rapidly internalized and degraded in intracellular organelles through a bafilomycin A(1)-sensitive mechanism, and (125)I-bearing low molecular mass fragment(s) were released in the culture medium. These different processes were inhibited by hydroxamic acid-based synthetic MMP inhibitors and rTIMP-2, but not by rTIMP-1 or cysteine, serine, or aspartic proteinase inhibitors. These results support the concept that the MT1-MMP-dependent internalization and degradation of TIMP-2 by some tumor cells might be involved in the regulation of pericellular proteolysis. [less ▲]

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See detailMembrane Type Matrix Metalloproreases in tumor angiogenesis
Sounni, Nor Eddine ULg

Conference (2005, January)

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See detailMembrane type-1 matrix metalloproteinase and TIMP-2 in tumor angiogenesis
Sounni, Nor Eddine ULg; Janssen, M.; Foidart, Jean-Michel ULg et al

in Matrix Biology (2003), 22(1), 55-61

The matrix metalloproteinases (MMPs) constitute a multigene family of over 23 secreted and cell-surface associated enzymes that cleave or degrade various pericellular substrates. In addition to virtually ... [more ▼]

The matrix metalloproteinases (MMPs) constitute a multigene family of over 23 secreted and cell-surface associated enzymes that cleave or degrade various pericellular substrates. In addition to virtually all extracellular matrix (ECM) compounds, their targets include other proteinases, chemotactic molecules, latent growth factors, growth factor-binding proteins and cell surface molecules. The MMP activity is controlled by the physiological tissue inhibitors of MMPs (TIMPs). There is much evidence that MMPs and their inhibitors play a key role during extracellular remodeling in physiological situations and in cancer progression. They have other functions that promoting tumor invasion. Indeed, they regulate early stages of tumor progression such as tumor growth and angiogenesis. Membrane type MMPs (MT-MMPs) constitute a new subset of cell surface-associated MMPs. The present review will focus on MT1-MMP which plays a major role at least, in the ECM remodeling, directly by degrading several of its components, and indirectly by activating pro-MMP2. As our knowledge on the field of MT1-MMP biology has grown, the unforeseen complexities of this enzyme and its interaction with its inhibitor TIMP-2 have emerged, often revealing unexpected mechanisms of action. (C) 2003 Elsevier Science B.V/Intemational Society of Matrix Biology. All rights reserved. [less ▲]

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See detailMembrane type-matrix metalloproteinases and tumor progression
Sounni, Nor Eddine ULg; Noël, Agnès ULg

in Biochimie (2005), 87

Matrix metalloproteinases (MMPs) are a family of zinc endopeptidases that process growth factors, growth factor binding proteins, cell surface proteins, degrade extracellular matrix (ECM) components and ... [more ▼]

Matrix metalloproteinases (MMPs) are a family of zinc endopeptidases that process growth factors, growth factor binding proteins, cell surface proteins, degrade extracellular matrix (ECM) components and thereby play a central role in tissue remodeling and tumor progression. Membrane-type matrix metalloproteinases (MT-MMPs) are a recently discovered subgroup of intrinsic plasma membrane proteins. Their functions have been extended from pericellular proteolysis and control of cell migration to cell signaling, control of cell proliferation and regulation of multiple stages of tumor progression including growth and angiogenesis. This review sheds light on the new functions of MT-MMPs and their inhibitors in tumor development and angiogenesis, and presents recent investigations that document their influence on various cell functions. [less ▲]

Detailed reference viewed: 33 (4 ULg)