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See detailCell cholesterol modulates metalloproteinase-dependent shedding of low-density lipoprotein receptor-related protein-1 (LRP-1) and clearance function.
Selvais, C.; D'Auria, L.; Tyteca, D. et al

in FASEB Journal (2011), 25(8), 2770-2781

Low-density lipoprotein receptor-related protein-1 (LRP-1) is a plasma membrane scavenger and signaling receptor, composed of a large ligand-binding subunit (515-kDa α-chain) linked to a shorter ... [more ▼]

Low-density lipoprotein receptor-related protein-1 (LRP-1) is a plasma membrane scavenger and signaling receptor, composed of a large ligand-binding subunit (515-kDa α-chain) linked to a shorter transmembrane subunit (85-kDa β-chain). LRP-1 cell-surface level and function are controlled by proteolytic shedding of its ectodomain. Here, we identified ectodomain sheddases in human HT1080 cells and demonstrated regulation of the cleavage by cholesterol by comparing the classical fibroblastoid type with a spontaneous epithelioid variant, enriched ∼2-fold in cholesterol. Two membrane-associated metalloproteinases were involved in LRP-1 shedding: a disintegrin and metalloproteinase-12 (ADAM-12) and membrane-type 1 matrix metalloproteinase (MT1-MMP). Although both variants expressed similar levels of LRP-1, ADAM-12, MT1-MMP, and specific tissue inhibitor of metalloproteinases-2 (TIMP-2), LRP-1 shedding from epithelioid cells was ∼4-fold lower than from fibroblastoid cells. Release of the ectodomain was triggered by cholesterol depletion in epithelioid cells and impaired by cholesterol overload in fibroblastoid cells. Modulation of LRP-1 shedding on clearance was reflected by accumulation of gelatinases (MMP-2 and MMP-9) in the medium. We conclude that cholesterol exerts an important control on LRP-1 levels and function at the plasma membrane by modulating shedding of its ectodomain, and therefore represents a novel regulator of extracellular proteolytic activities.-Selvais, C., D'Auria, L., Tyteca, D., Perrot, G, Lemoine, P., Troeberg, L., Dedieu, S., Noël, A., Nagase, H., Henriet, P., Courtoy, P. J., Marbaix, E., Emonard, H. Cell cholesterol modulates metalloproteinase-dependent shedding of low-density lipoprotein receptor-related protein-1 (LRP-1) and clearance function. [less ▲]

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See detailCell cultivation in chitosan alginate hydrogel beads
Henrotin, Yves ULg; Kesteloot, Frédéric; Sanchez, Christelle ULg

Patent (2014)

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See detailCELL CULTIVATION IN CHITOSAN ALGINATE HYDROGEL BEADS
Henrotin, Yves ULg; Kesteloot, Frédéric; Sanchez, Christelle ULg

Patent (2011)

The present invention relates to a method of producing a hydrogel matrix comprising cartilage-forming cells wherein alginate, chitosan and cartilage- forming cells are mixed and subsequently polymerised ... [more ▼]

The present invention relates to a method of producing a hydrogel matrix comprising cartilage-forming cells wherein alginate, chitosan and cartilage- forming cells are mixed and subsequently polymerised into beads. [less ▲]

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See detailCell cultivation in chitosan alginate hydrogel beads
Henrotin, Yves ULg; Kesteloot, Frédéric; Sanchez, Christelle ULg

Patent (2011)

The present invention relates to a method of producing a hydrogel matrix comprising cartilage-forming cells wherein alginate, chitosan and cartilage-forming cells are mixed and subsequently polymerised ... [more ▼]

The present invention relates to a method of producing a hydrogel matrix comprising cartilage-forming cells wherein alginate, chitosan and cartilage-forming cells are mixed and subsequently polymerised into beads. [less ▲]

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See detailCell cycle activation of hematopoietic progenitor cells increases very late antigen-5-mediated adhesion to fibronectin.
Giet, Olivier ULg; Huygen, Sandra; Beguin, Yves ULg et al

in Experimental hematology (2001), 29(4), 515-24

Recent studies suggested that trafficking of hematopoietic progenitor cells is related to cell cycle status. We studied whether adhesion of progenitor cells to extracellular matrix proteins was modulated ... [more ▼]

Recent studies suggested that trafficking of hematopoietic progenitor cells is related to cell cycle status. We studied whether adhesion of progenitor cells to extracellular matrix proteins was modulated by cell cycle transit.Mobilized peripheral blood CD34+ cells were stimulated ex vivo for 48 hours with stem cell factor, flt-3 ligand, and thrombopoietin and fractionated by adhesion to fibronectin or vascular cell adhesion molecule-1 (VCAM-1). Adherent and nonadherent cells were assayed for cell cycle status, long-term culture-initiating cell frequency, and integrin function. Binding to fibronectin, but not to VCAM-1, displayed a cell cycle selectivity as the adherent fraction to fibronectin was enriched in cycling CD34+ cells and in cycling long-term culture-initiating cells compared to the nonadherent fraction. Combined cell cycle and phenotypic analysis showed that the expression of VLA-5 was upregulated during S/G2+M but that of VLA-4 remained constant. The selective binding of cycling CD34+ cells to fibronectin was reverted by anti-VLA-5 but not by anti-VLA-4 blocking antibodies. Also, cycling CD34+ cells preferentially adhered to the VLA-5 binding domain but not to the VLA-4 binding domain of fibronectin. Adhesion of cycling CD34+ cells to fibronectin was a reversible process modulated by cell cycle progression, because adherent cells could exit the cell cycle and return to a nonadhesive state within an additional 48-hour culture period.The results indicate that the enhanced binding capacity of cycling progenitor cells to fibronectin is mediated by VLA-5. [less ▲]

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See detailCell cycle duration at the time of maternal zygotic transition for in vitro produced bovine embryos: effect of oxygen tension and transcription inhibition.
Lequarré, Anne-Sophie ULg; Marchandise, J.; Massip, A. et al

in Biology of Reproduction (2003), 69(5), 1707-13

Early embryonic cleavages are mostly regulated by maternal components then control of development progressively depends on newly synthesized zygotic products. The timing of the first cleavages is a way to ... [more ▼]

Early embryonic cleavages are mostly regulated by maternal components then control of development progressively depends on newly synthesized zygotic products. The timing of the first cleavages is a way to assess embryo quality. The goal of this study was to evaluate the duration of the fourth cell cycle, at the time of maternal-to-zygotic transition (MZT) in in vitro-produced bovine embryos by means of cinematographic analysis. We found that 75% of the embryos displayed a long fourth cycle (43.5 +/- 5.4 h) whereas the remaining embryos had a very short fourth cell cycle (8.9 +/- 2.9 h). Both groups did not differ in cleavage rhythm up to the eight-cell stage and timing of cavitation and blastocyst expansion was identical. However, embryos with a short fourth cell cycle had a better blastocyst rate than embryos with a long cycle (59% versus 38%, P < 0.01). Total cell number, inner cell mass (ICM):total cell ratio, and hatching rate were identical for blastocysts produced from embryos with either a long or a short fourth cell cycle. In a second experiment, we showed that increasing the oxygen tension, from 5% to 20%, decreased the percentage of embryos with a short fourth cell cycle, from 25% to 11% (P < 0.01), indicating that suboptimal culture conditions can influence the length of this cycle. Finally, we investigated whether fourth cell cycle duration could be influenced by transcription inhibition. With alpha-amanitin added at 18 h postinsemination (HPI), cleavage was reduced (66% versus 79%) and, at 70 HPI, the 9- to 16-cell rate increased (50% versus 25%) concomitantly with a 5- to 8-cell rate decrease (16% versus 47%). A similar pattern was observed when the drug was added at 6 HPI or 42 HPI but not at 0 HPI. Cinematographic analysis revealed that alpha-amanitin increased the first cell cycle duration whereas the second and third cell cycles were not affected. With the drug, one third of the embryos could develop up to the 9- to 16-cell stage and they all had a short fourth cell cycle (11.2 +/- 3.7 h) with a good synchrony of cleavage between blastomeres. These results suggest that duration of the fourth cell cycle of bovine embryo, during the MZT, is under a zygotic transcriptional control that can be affected by oxidative conditions. [less ▲]

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See detailCell cycle S phase markers are expressed in cerebral neuron nuclei of cats infected by the Feline Panleukopenia Virus
Poncelet, Luc; Garigliany, Mutien-Marie ULg; Ando et al

in Cell Cycle (Georgetown, Tex.) (2016), 15(24), 3482-3489

The cell cycle-associated neuronal death hypothesis, which has been proposed as a common mechanism for most neurodegenerative diseases, is notably supported by evidencing cell cycle effectors in neurons ... [more ▼]

The cell cycle-associated neuronal death hypothesis, which has been proposed as a common mechanism for most neurodegenerative diseases, is notably supported by evidencing cell cycle effectors in neurons. However, in naturally occurring nervous system diseases, these markers are not expressed in neuron nuclei but in cytoplasmic compartments. In other respects, the Feline Panleukopenia Virus (FPV) is able to complete its cycle in mature brain neurons in the feline species. As a parvovirus, the FPV is strictly dependent on its host cell reaching the cell cycle S phase to start its multiplication. In this retrospective study on the whole brain of 12 cats with naturally-occurring, FPV-associated cerebellar atrophy, VP2 capsid protein expression was detected by immunostaining not only in some brain neuronal nuclei but also in neuronal cytoplasm in 2 cats, suggesting that viral mRNA translation was still occurring. In these cats, double immunostainings demonstrated the expression of cell cycle S phase markers cyclin A, cdk2 and PCNA in neuronal nuclei. Parvoviruses are able to maintain their host cells in S phase by triggering the DNA damage response. S139 phospho H2A1, a key player in the cell cycle arrest, was detected in some neuronal nuclei, supporting that infected neurons were also blocked into the S phase. PCR studies did not support a co-infection with an adeno or herpes virus. ERK1/2 nuclear accumulation was observed in some neurons suggesting that the ERK signaling pathway might be involved as a mechanism driving these neurons far into the cell cycle. [less ▲]

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See detailCell cycle-related changes in repopulating capacity of human mobilized peripheral blood CD34(+) cells in non-obese diabetic/severe combined immune-deficient mice.
GOTHOT, André ULg; Van der loo, J. C. M.; Clapp, D. W. et al

in Blood (1998), 92(8), 2641-9

Most primitive hematopoietic progenitor cells reside in vivo within the G0/G1 phase of the cell cycle. By simultaneous DNA/RNA staining it is possible to distinguish G0 and G1 states and to isolate cells ... [more ▼]

Most primitive hematopoietic progenitor cells reside in vivo within the G0/G1 phase of the cell cycle. By simultaneous DNA/RNA staining it is possible to distinguish G0 and G1 states and to isolate cells in defined phases of the cell cycle. We report here the use of cell cycle fractionation to separate human mobilized peripheral blood (MPB) CD34(+) cells capable of repopulating the bone marrow (BM) of non-obese diabetic/severe combined immune-deficient (NOD/SCID) mice. In freshly isolated MPB, repopulating cells were predominant within the G0 phase, because transplantation of CD34(+) cells residing in G0 (G0CD34(+)) resulted on average in a 16.6- +/- 3.2-fold higher BM chimerism than infusion of equal numbers of CD34(+) cells isolated in G1. We then investigated the effect of ex vivo cell cycle progression, in the absence of cell division, on engraftment capacity. Freshly isolated G0CD34(+) cells were activated by interleukin-3 (IL-3), stem cell factor (SCF), and flt3-ligand (FL) for a 36-hour incubation period during which a fraction of cells progressed from G0 into G1 but did not complete a cell cycle. The repopulating capacity of stimulated cells was markedly diminished compared with that of unmanipulated G0CD34(+) cells. Cells that remained in G0 during the 36-hour incubation period and those that traversed into G1 were sorted and assayed separately in NOD/SCID recipients. The repopulating ability of cells remaining in G0 was insignificantly reduced compared with that of unstimulated G0CD34(+) cells. On the contrary, CD34(+) cells traversing from G0 into G1 were largely depleted of repopulating capacity. Similar results were obtained when G0CD34(+) cells were activated by the combination of thrombopoietin-SCF-FL. These studies provide direct evidence of the quiescent nature of cells capable of repopulating the BM of NOD/SCID mice. Furthermore, these data also demonstrate that G0-G1 progression in vitro is associated with a decrease in engraftment capacity. [less ▲]

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See detailCell death and growth arrest in response to photodynamic therapy with membrane-bound photosensitizers
Piette, Jacques ULg; Volanti, Cédric ULg; Vantieghem, Annelies et al

in Biochemical Pharmacology (2003), 66(8), 1651-1659

Photodynamic therapy (PDT) is a treatment for cancer and for certain benign conditions that is based on the use of a photosensitizer and light to produce reactive oxygen species in cells. Many of the ... [more ▼]

Photodynamic therapy (PDT) is a treatment for cancer and for certain benign conditions that is based on the use of a photosensitizer and light to produce reactive oxygen species in cells. Many of the photosensitizers currently used in PDT localize in different cell compartments such as mitochondria, lysosomes, endoplasmic reticulum and generate cell death by triggering necrosis and/or apoptosis. Efficient cell death is observed when light, oxygen and the photosensitizer are not limiting ("high dose PDT"). When one of these components is limiting ("low dose PDT"), most of the cells do not immediately undergo apoptosis or necrosis but are growth arrested with several transduction pathways activated. This commentary will review the mechanism of apoptosis and growth arrest mediated by two important PDT agents. i.e. pyropheophorbide and hypericin. (C) 2003 Elsevier Inc. All rights reserved. [less ▲]

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See detailCell death signaling in cancer cells treated by Photodynamic Therapy
Fettweis, Grégory ULg

Doctoral thesis (2016)

Glioblastoma multiformes (GBMs) are an extremely aggressive and infiltrating type of brain cancer. Despite heavy therapies and extensive fundamental and applied research, the median survival of patients ... [more ▼]

Glioblastoma multiformes (GBMs) are an extremely aggressive and infiltrating type of brain cancer. Despite heavy therapies and extensive fundamental and applied research, the median survival of patients remains about 15 months after diagnosis for over a decade. Therefore, there is an emergency to find new approaches and therapeutic targets for treating this cancer. Photodynamic therapy (PDT) recently demonstrated a high potential in the treatment of GBM. Moreover, GBMs induced cell death by PDT is dependent of an atypical RIP3-dependent programmed necrosis. In parallel, GBMs activate a pro-survival autophagic pathway in order to recycle PDT-damaged structures and organelles. In our PhD thesis, we investigated the regulation of this autophagic process and found that TSC2 protein had an important role in autophagy activation by PDT. Indeed, PDT treatment quickly activates the kinase MK2, which phosphorylates TSC2 on serine 1254. We then showed that phosphorylation of this serine was crucial for autophagy activation, which makes TSC2 a crucial pro-survival factor in GBMs treated with PDT. Finally, we demonstrated that protein 14-3-3 ζ (YWHAZ) interacts with TSC2 and protects TSC2 serine 1254 phosphorylation from phosphatase actions after PDT. In the same time we conducted a proteomic analysis on RIP3 immunoprecipitate. The major implication of this analysis is the demonstration that RIP3 interacts with TSC2 and YWHAZ. Finally, we showed that RIP3 interacts better with the non-phosphorylated form of TSC2 than with the phosphorylated form, suggesting a RIP3 interference in the TSC2-dependent autophagy activation process. These data were submitted for publication in "Scientific Reports". In the second part of this thesis, we also investigated the influence of RIP3 expression on osteosarcoma (U2OS) cell death. U2OS expressing or not RIP3 were treated with PDT and cell death mechanisms have been investigated. We first demonstrated that in both cell lines, apoptosis was the major cell death mechanism. Secondly, we noticed an over-activation of various caspases in cells expressing RIP3 despite a stronger resistance to PDT. This could be explained by a lower activation of autophagy in cells not expressing RIP3. Thirdly, we showed that in RIP3 expressing cells, residual necrosis was RIP1-dependent. We therefore suggest that RIP3 is able to influence the cell death process. These data were published in "Laser in surgery and medicine." [less ▲]

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See detailCell dynamics and immune response to BLV infection: a unifying model
Florins, Arnaud-Francois ULg; Gillet, Nicolas ULg; Asquith, Becca et al

in Frontiers in Bioscience : A Journal and Virtual Library (2007), 12

Bovine Leukemia virus (BLV) is the natural etiological agent of a lymphoproliferative disease in cattle. BLV can also be transmitted experimentally to a related ruminant species, sheep, in which the ... [more ▼]

Bovine Leukemia virus (BLV) is the natural etiological agent of a lymphoproliferative disease in cattle. BLV can also be transmitted experimentally to a related ruminant species, sheep, in which the pathogenesis is more acute. Although both susceptible species develop a strong anti-viral immune response, the virus persists indefinitely throughout life, apparently at a transcriptionally silent stage, at least in a proportion of infected cells. Soon after infection, these humoral and cytotoxic activities very efficiently abolish the viral replicative cycle, permitting only mitotic expansion of provirus-carrying cells. Short term cultures of these infected cells initially indicated that viral expression protects against spontaneous apoptosis, suggesting that leukemia is a process of accumulation of long-lived cells. This conclusion was recently reconsidered following in vivo dynamic studies based on perfusions of nucleoside (bromodeoxyuridine) or fluorescent protein markers (CFSE). In sheep, the turnover rate of infected cells is increased, suggesting that a permanent clearance process is exerted by the immune system. Lymphocyte trafficking from and to the secondary lymphoid organs is a key component in the maintenance of cell homeostasis. The net outcome of the immune selective pressure is that only cells in which the virus is transcriptionally silenced survive and accumulate, ultimately leading to lymphocytosis. Activation of viral and/or cellular expression in this silent reservoir with deacetylase inhibitors causes the collapse of the proviral loads. In other words, modulation of viral expression appears to be curative in lymphocytic sheep, an approach that might also be efficient in patients infected with the related Human T-lymphotropic virus type 1. In summary, a dynamic interplay between BLV and the host immune response modulates a complex equilibrium between (i) viral expression driving (or) favoring proliferation and (ii) viral silencing preventing apoptosis. As conclusion, we propose a hypothetical model unifying all these mechanisms. [less ▲]

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See detailThe cell envelope in Proteus vulgaris P 18 : Isolation and characterization of the peptidoglycan component
Fleck, J.; Mock, M.; Minck, R. et al

in Biochimica et Biophysica Acta - Biomembranes (1971), 223(3), 489-503

Degradation of heat-treated cells of Proteus vulgaris P 18 with a protease preparation from a soil Bacillus subtilis allowed the isolation of a cell envelope structural entity, 60-70 Å thick, consisting ... [more ▼]

Degradation of heat-treated cells of Proteus vulgaris P 18 with a protease preparation from a soil Bacillus subtilis allowed the isolation of a cell envelope structural entity, 60-70 Å thick, consisting of two electron-dense layers separated by a light one and composed, at least in part, of lipopolysaccharide O-antigen and of peptidoglycan. An enriched preparation, of which 55 % of the dry weight consisted of an intact peptidoglycan, was obtained through the sequential action upon lyophilized cells of hot aqueous sodium dodecyl sulfate and B. subtilis protease. Both Chalaropsis B endo-N-acetylmuramidase and Streptomyces DD carboxy-peptidase solubilized the enriched peptidoglycan preparation. The Chalaropsis enzyme completely degraded the glycan moiety into peptide-substituted disaccharide units. The DD carboxypeptidase hydrolyzed the D-alanyl-(D)-meso-diaminopimelic acid linkages involved in peptide cross-linking. In the intact peptidoglycan, about 35 % of the L-alanyl-γ-D-glutamyl-(L)-meso-diaminopimelic acid-(L)-D-alanine residues occurred as uncross-linked monomers, 40 % of them as peptide dimers and 16 % as peptide trimers. It is likely that not all the peptides retained the D-alanine residue at their C-termini. About half of the N-acetylmuramic acid residues in the glycan moiety are O-acetylated, a property which is compatible with the high lysozyme resistance exhibited by the P. vulgaris peptidoglycan. [less ▲]

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See detailCell factories for the production of bioactive peptides from Bacillus subtilis and Pseudomonas.
Vater, J.; Venema, G.; Thonart, Philippe ULg et al

Poster (1997, April)

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See detailCell Handling, Membrane-Binding Properties, And Membrane-Penetration Modeling Approaches Of Pivampicillin And Phthalimidomethylampicillin, Two Basic Esters Of Ampicillin, In Comparison With Chloroquine And Azithromycin
Chanteux, H.; Paternotte, I.; Mingeot-Leclercq, Mp. et al

in Pharmaceutical Research (2003), 20(4), 624-31

PURPOSE: The purpose of this work was to examine and understand the cellular pharmacokinetics of two basic esters of ampicillin, pivaloyloxymethyl (PIVA) and phthalimidomethyl (PIMA), in comparison with ... [more ▼]

PURPOSE: The purpose of this work was to examine and understand the cellular pharmacokinetics of two basic esters of ampicillin, pivaloyloxymethyl (PIVA) and phthalimidomethyl (PIMA), in comparison with lysosomotropic drugs (chloroquine, azithromycin). METHODS: Cell culture studies (J774 macrophages) were undertaken to study uptake and release kinetics and to assess the influence of concentration, pH, proton ionophore (monensin), and MRP and P-gp inhibitors (probenecid, gemfibrozil, cyclosporin A, GF 120918). Equilibrium dialysis with liposomes were performed to directly asses the extent of drug binding to bilayers. Conformational analysis modeling of the drug penetration in bilayers was conducted to rationalize the experimental observations. RESULTS: PIVA and PIMA showed properties in almost complete contrast with those of chloroquine and azithromycin, i.e., fast apparent accumulation and fast release at 4 degrees C as well as at 37 degrees C, saturation of uptake (apparent Kd 40 microM), no influence of monensin, MRP, or P-gp inhibitors; tight binding to liposomes (Kd approx. 40 microM); and sharp increase in calculated free energy when forced in the hydrophobic domain. CONCLUSIONS: Although they are weak organic bases, PIVA and PIMA show none of the properties of lysosomotropic agents. We hypothesize that they remain locked onto the pericellular membrane and may never penetrate cells as such in significant amounts. [less ▲]

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See detailCell invasion in the spheroid sprouting assay: a spatial organisation analysis adaptable to cell behaviour.
Blacher, Silvia ULg; Erpicum, Charlotte ULg; Lenoir, Benedicte et al

in PLoS ONE (2014), 9(5), 97019

The endothelial cell spheroid assay provides a suitable in vitro model to study (lymph) angiogenesis and test pro- and anti-(lymph) angiogenic factors or drugs. Usually, the extent of cell invasion ... [more ▼]

The endothelial cell spheroid assay provides a suitable in vitro model to study (lymph) angiogenesis and test pro- and anti-(lymph) angiogenic factors or drugs. Usually, the extent of cell invasion, observed through optical microscopy, is measured. The present study proposes the spatial distribution of migrated cells as a new descriptor of the (lymph) angiogenic response. The utility of this novel method rests with its capacity to locally characterise spheroid structure, allowing not only the investigation of single and collective cell invasion but also the evolution of the spheroid core itself. Moreover, the proposed method can be applied to 2D-projected spheroid images obtained by optical microscopy, as well as to 3D images acquired by confocal microscopy. To validate the proposed methodology, endothelial cell invasion was evaluated under different experimental conditions. The results were compared with widely used global parameters. The comparison shows that our method prevents local spheroid modifications from being overlooked and leading to the possible misinterpretation of results. [less ▲]

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See detailCell localization and redistribution of the 67 kD laminin receptor and alpha 6 beta 1 integrin subunits in response to laminin stimulation: an immunogold electron microscopy study.
Romanov, V.; Sobel, M. E.; pinto da Silva, P. et al

in Cell Adhesion and Communication (1994), 2(3), 201-9

The 67 kDa laminin receptor (67LR), one of several cell surface laminin-binding proteins, is involved in the interactions between cancer cells and laminin during tumor invasion and metastasis. A 37 kDa ... [more ▼]

The 67 kDa laminin receptor (67LR), one of several cell surface laminin-binding proteins, is involved in the interactions between cancer cells and laminin during tumor invasion and metastasis. A 37 kDa polypeptide (37LRP), previously identified as the 67LR precursor, is abundantly present in the cytoplasm and has been implicated in polysome formation. To better understand the cellular localization of the 67LR and its precursor, transmission electron microscopic studies of human melanoma A2058 cells were carried out using immunogold labeling and a variety of antibodies: (a) affinity purified antibodies directed against 37LRP cDNA-derived synthetic peptides; (b) anti-67LR monoclonal antibodies raised against intact human small cell lung carcinoma cells; and (c) monoclonal antibodies against the subunits of the integrin laminin receptor, alpha 6 beta 1. Double-labeling immunocyto-chemistry revealed that anti-67LR monoclonal antibodies as well as anti-37 LRP antibodies recognized antigens that were localized in the cytoplasm in electron dense structures. As expected, cell membrane labeling was also observed. Surprisingly, alpha 6 and beta 1 integrin subunits were detected in the same cytoplasmic structures positive for the 67LR and the 37LRP. After addition of soluble laminin to A2058 cells in suspension, the number of labeled cytoplasmic structures increased especially in the vicinity of the plasma membrane, and were exported onto the cell surface. Neither fibronectin nor BSA induced such an effect. The data demonstrate that the 67 LR and the 37 LRP antibodies detect colocalized antigens that are in cytoplasmic structures with alpha 6 beta 1 integrin.(ABSTRACT TRUNCATED AT 250 WORDS) [less ▲]

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See detailCell lysis during coccolithophorid blooms in the Northern Bay of Biscay
De Bodt, Caroline; Harlay, Jérôme ULg; Roevros, Nathalie et al

Poster (2009, January 25)

Phytoplankton cell lysis occurs in natural populations and is often associated with viral activity and zooplankton grazing. Cell lysis rates are expected to increase towards the decaying phase of the ... [more ▼]

Phytoplankton cell lysis occurs in natural populations and is often associated with viral activity and zooplankton grazing. Cell lysis rates are expected to increase towards the decaying phase of the bloom and may be associated with enhanced microbial activity and export of particulate matter to the seafloor. Their estimation was based on the measurement of esterase (a cytoplasmic enzyme) activity expected to appear in the water only after cell breakage. Field investigations, supported by remote sensing data, were conducted in recent years during late spring in the Northern Bay of Biscay, where frequent and recurrent coccolithophorid blooms are observed. Results on cell lysis rates determined in surface waters will be presented with relevant biogeochemical parameters (temperature, particulate organic and inorganic carbon, transparent exopolymer particles, nutrients, chlorophyll a) in order to investigate phytoplankton dynamics in relation to coccolithophorid development. The use of this parameter to characterize bloom termination, especially during coccolithophorid blooms will be discussed. [less ▲]

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See detailCell membrane proteomic analysis identifies proteins differentially expressed in osteotropic human breast cancer cells.
Kischel, Philippe ULg; Guillonneau, Francois; Dumont, Bruno ULg et al

in Neoplasia : An International Journal for Oncology Research (2008), 10(9), 1014-20

Metastatic breast cancer cells are characterized by their high propensity to colonize the skeleton and form bone metastases, causing major morbidity and mortality. Identifying key proteins involved in the ... [more ▼]

Metastatic breast cancer cells are characterized by their high propensity to colonize the skeleton and form bone metastases, causing major morbidity and mortality. Identifying key proteins involved in the osteotropic phenotype would represent a major step toward the development of both new prognostic markers and new effective therapies. Cell surface proteins differentially expressed in cancer cells are preferred potential targets for antibody-based targeted therapies. In this study, using cell surface biotinylation and a mass spectrometric approach, we have compared the profile of accessible cell surface proteins between the human breast cancer cell line MDA-MB-231 and its highly osteotropic B02 subclone. This strategy allowed the identification of several proteins either up- or downregulated in the osteotropic cell line, and differential protein expressions were validated using antibody-based techniques. Class I HLAs were down-regulated in the bone metastatic variant, whereas alpha(v)beta(3) integrins, among others, were consistently up-regulated in this latter cell line. These results show that comprehensive profiling of the cell surface proteome of mother cancerous cell lines and derived organ-specific metastatic cell lines provides an effective approach for the identification of potential accessible marker proteins for both prognosis and antibody-based targeted therapies. [less ▲]

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See detailCell Models Adapted to Real-Time Imaging of the Cytoskeleton Dynamics in Altered Gravity
Willems, Jérôme ULg; Deroanne, Christophe ULg; Colige, Alain ULg et al

in Microgravity Science and Technology (2014), 26(4), 257-270

Spatial and temporal regulation of cell phenotype by mechanical forces is a growing field of research in health sciences since these stimuli influence cellular functions, such as proliferation, migration ... [more ▼]

Spatial and temporal regulation of cell phenotype by mechanical forces is a growing field of research in health sciences since these stimuli influence cellular functions, such as proliferation, migration, differentiation and gene expression. In the context of the Fluolive project selected by the European Space Agency and aiming at evaluating the impact of gravity alterations on the cell phenotype, we have developed new bone-derived cell lines adapted for live-cell imaging of the cytoskeleton. Osteoblastic cells derived from human osteosarcomas were used as experimental models. U2-OS and SaoS-2 cells stably expressing TagGFP2- β-actin and mCherry- α-tubulin were established and single-cell clonal cultures were characterized in terms of recombinant proteins production and localization, fluorescence intensity, cell proliferation and migration rates. Living fluorescently-tagged cell lines allow real-time fluorescence microscopy of the cytoskeleton dynamics without bleaching and without alteration of cell morphology. U2-OS and SaoS-2 TagGFP2- β-actin and mCherry- α-tubulin clones will be used to monitor the effect of mechanical forces in models of altered gravity on Earth and possibly on the ISS. © 2014, Springer Science+Business Media Dordrecht. [less ▲]

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