Fibrinogen (fg), present in tumor matrices, has been demonstrated to be determinant in metastatic potential. We have recently shown that fg/ICAM-1 interactions are involved in leukocyte migration across endothelial cell monolayers. Using... more
Fibrinogen (fg), present in tumor matrices, has been demonstrated to be determinant in metastatic potential. We have recently shown that fg/ICAM-1 interactions are involved in leukocyte migration across endothelial cell monolayers. Using bladder transitional cell carcinoma as a model, we will show in this study that bladder high grade tumor cell lines express ICAM-1, and that this expression induces an fg-mediated migration. This phenomenon was dependent on ICAM-1/fg interaction as well as RhoA activity. ICAM-1 was concentrated in focal adhesion plaques when tumor cells were allowed to adhere on immobilized fg, suggesting a role in cell migration. The addition of fg induced a 3- to 6-fold enhancement of bladder tumor cell migration through HUVEC monolayers. This process was inhibited by an anti-ICAM-1 antibody blocking fg binding, demonstrating that ICAM-1/fg interaction was involved in the extravasation process. Finally, immunohistological studies revealed that the expression of IC...
Research Interests:
The MSRV (multiple sclerosis-associated retrovirus) belongs to the human endogenous retrovirus HERV-W family. The envelope protein originating from the MSRV has been found in most patients with multiple sclerosis (MS). This protein... more
The MSRV (multiple sclerosis-associated retrovirus) belongs to the human endogenous retrovirus HERV-W family. The envelope protein originating from the MSRV has been found in most patients with multiple sclerosis (MS). This protein (Env-ms) has pro-inflammatory properties for several types of immune cells and could therefore play a role in MS pathogenesis by promoting the leukocyte diapedesis observed in the central nervous system of patients. Our study aims to analyze the effects of Env-ms on the blood-brain barrier (BBB) at a molecular and functional level. We demonstrate that the recombinant MSRV envelope is able to stimulate several inflammatory parameters in a human BBB in vitro model, the HCMEC/D3 brain endothelial cell line. Indeed, Env-ms induces over-expression of ICAM-1, a major mediator of leukocyte adhesion to endothelial cells, in a dose-dependent manner as well as a strong dose-dependent production of the pro-inflammatory cytokines IL-6 and IL-8. Furthermore, using a s...
Research Interests:
Fibrinogen (fg), present in tumor matrices, has been demonstrated to be determinant in metastatic potential. We have recently shown that fg/ICAM-1 interactions are involved in leukocyte migration across endothelial cell monolayers. Using... more
Fibrinogen (fg), present in tumor matrices, has been demonstrated to be determinant in metastatic potential. We have recently shown that fg/ICAM-1 interactions are involved in leukocyte migration across endothelial cell monolayers. Using bladder transitional cell carcinoma as a model, we will show in this study that bladder high grade tumor cell lines express ICAM-1, and that this expression induces an fg-mediated migration. This phenomenon was dependent on ICAM-1/fg interaction as well as RhoA activity. ICAM-1 was concentrated in focal adhesion plaques when tumor cells were allowed to adhere on immobilized fg, suggesting a role in cell migration. The addition of fg induced a 3- to 6-fold enhancement of bladder tumor cell migration through HUVEC monolayers. This process was inhibited by an anti-ICAM-1 antibody blocking fg binding, demonstrating that ICAM-1/fg interaction was involved in the extravasation process. Finally, immunohistological studies revealed that the expression of IC...
Research Interests:
Research Interests:
Research Interests: Biomedical Engineering, Rheology, Biorheology, Cell Adhesion, Atomic Force Microscopy, and 13 moreAdhesion, Cytoskeleton, Elasticity, Cellular mechanotransduction, AFM, Animals, Microrheology, Viscosity, Single Cell, Clinical Sciences, Rheological properties, Mechanical Stress, and Viscoelastic Properties
Eukaryotic cells and biological materials are described from a rheological point of view. Single cells possess typical microrheological properties which can affect cell behaviour, in close connection with their adhesion properties. Single... more
Eukaryotic cells and biological materials are described from a rheological point of view. Single cells possess typical microrheological properties which can affect cell behaviour, in close connection with their adhesion properties. Single cell properties are also important in the context of multicellular systems, i.e. in biological tissues. Results from experiments are analyzed and models proposed both at the cellular scale and the macroscopic scale. To cite this article: C. Verdier et al., C. R. Physique 10 (2009).
Research Interests:
Research Interests:
An original samarium(III) complex based on a triazacyclononane platform functionalized with a charge-transfer antenna chromophore exhibited optimized brightness and was successfully used as an emissive species for two-photon microscopy... more
An original samarium(III) complex based on a triazacyclononane platform functionalized with a charge-transfer antenna chromophore exhibited optimized brightness and was successfully used as an emissive species for two-photon microscopy experiments in both the visible and near-infrared spectral ranges.
Research Interests:
Research Interests:
ABSTRACT
Research Interests:
Research Interests:
Leukocyte-endothelium interactions and general inflammatory responses are contributed by the regulated expression of intercellular adhesion molecule-1 (ICAM-1) on endothelium. It is now shown by confocal fluorescence microscopy and... more
Leukocyte-endothelium interactions and general inflammatory responses are contributed by the regulated expression of intercellular adhesion molecule-1 (ICAM-1) on endothelium. It is now shown by confocal fluorescence microscopy and immunogold transmission electron microscopy that ICAM-1 was exclusively localized on the apical (luminal) membrane of cytokine-activated human umbilical vein endothelial cells. In contrast, other cell adhesion-promoting molecules, including beta 1 integrins, were expressed exclusively on the basolateral endothelial cell membrane, under the same experimental conditions. Kinetic binding studies of a 125I-labeled monoclonal antibody to ICAM-1 revealed that approximately 8% of membrane ICAM-1 on cytokine-activated endothelium was internalized in both coated and non-coated vesicles at 37 degrees C, with a t1/2 of approximately 18 min and a rate of approximately 3200 molecules/minute. This internalization pathway was directly dependent upon the level of ICAM-1 expression on the cell surface. Genetically engineered ICAM-1 transfectants, expressing a 10-fold higher receptor density than activated endothelium, internalized approximately 18% of membrane ICAM-1 at a rate of 75,000 molecules/minute with a t1/2 of approximately 22 min. These findings suggest that a combined pathway of polarized membrane topography and receptor trafficking may regulate ICAM-1-dependent adhesion at the site of vascular injury and endothelial cell activation.
Research Interests:
Research Interests:
Endothelial cell (EC) junctions regulate circulating leukocyte extravasation and infiltration at inflammatory sites. Several lines of evidence show that platelet endothelial cell adhesion molecule-1 (PECAM-1), a specific component of EC... more
Endothelial cell (EC) junctions regulate circulating leukocyte extravasation and infiltration at inflammatory sites. Several lines of evidence show that platelet endothelial cell adhesion molecule-1 (PECAM-1), a specific component of EC junctions, is required for leukocyte transmigration through EC monolayers. In this paper, we examined the effects of two inflammatory cytokines, TNF-alpha and IFN-gamma, on PECAM-1 and vascular endothelial-cadherin/catenin organization. We found that the addition of inflammatory cytokines (TNF-alpha plus IFN-gamma in combination, for > or = 24 h) caused PECAM-1 to disappear from EC intercellular contacts. Confocal microscopy indicated that after treatment with the cytokines, PECAM-1 was rapidly internalized. In addition, a strong inhibition of PECAM-1 synthesis and a decrease in PECAM-1 mRNA were observed. This phenomenon was only found when TNF-alpha plus IFN-gamma were used in combination. Adhesion of polymorphonuclear cells to doubly treated EC...
Research Interests:
The motion of a deformable leukocyte or cancer cell through a capillary or blood vessel is studied numerically and experimentally. Under certain physiological conditions (flow rate, etc.), the cell begins to adhere to the endothelium, and... more
The motion of a deformable leukocyte or cancer cell through a capillary or blood vessel is studied numerically and experimentally. Under certain physiological conditions (flow rate, etc.), the cell begins to adhere to the endothelium, and eventually rolls, deforms and extravasates through the endothelium. A two-component model with constant cortical tension is used to represent the white blood cells. Specifically, the model consists of plasma (surrounding liquid, Newtonian fluid); cytoplasm (outer layer, Oldroyd-B fluid) and nucleus (inner layer, Oldroyd-B fluid of a higher viscosity). The model allows us to track the position of the cell membrane and includes attraction forces due to a wall. Numerical and experimental results are given for the case of a cell rolling close to the wall.
Research Interests:
We present experiments involving T24 cancer cells adhering at the bottom of functionalized microchannels, and subjected to increasing shear rates. Morphological studies have been carried out at different shear stresses. Cells exhibit... more
We present experiments involving T24 cancer cells adhering at the bottom of functionalized microchannels, and subjected to increasing shear rates. Morphological studies have been carried out at different shear stresses. Cells exhibit spreading patterns similar to the ones observed in static conditions, as long as the shear stress is not too high. At a critical value of the wall shear stress, cells start to decrease their area until detachment is achieved for the larger stresses. The influence of microchannel size is also analyzed and shows a slight effect, enhanced for high confinement. To analyze such data, we propose a model to determine the 3D-shear stress necessary to achieve cell area decrease (leading to detachment), as a function of focal adhesion contacts present at the cell-substrate interface. Using this method, the determination of typical forces exerted at each focal contact can be achieved.
Research Interests:
We report on the laser fabrication of BSA and type I collagen microstructures using Eosin Y or Rose Bengal photo sensitizers. Similar cross-linking results have been obtained by one-photon absorption or two-photon absorption using a green... more
We report on the laser fabrication of BSA and type I collagen microstructures using Eosin Y or Rose Bengal photo sensitizers. Similar cross-linking results have been obtained by one-photon absorption or two-photon absorption using a green Q-switched microlaser or a near-infrared mode-locked Ti:sapphire laser, respectively. The microstructure resolution depends on the laser power, but is typically limited by the size of the laser beam within the sample. The cross-linking of type I collagen with Rose Bengal is obtained in acidic conditions with a large photosensitizer concentration in the millimole range. The biocompatibility of microstructures was demonstrated by observing the specific adhesion of cells on collagen lines.
Research Interests:
The platelet membrane glycoproteins GPIIb and GPIIIa form a calcium-dependent heterodimer that functions as a receptor for adhesive proteins on stimulated platelets. In this study, we have investigated the kinetics of the assembly... more
The platelet membrane glycoproteins GPIIb and GPIIIa form a calcium-dependent heterodimer that functions as a receptor for adhesive proteins on stimulated platelets. In this study, we have investigated the kinetics of the assembly reaction that result in GPIIb-IIIa dimerization. Pulse-chase experiments analysis performed on human megakaryocytes obtained from liquid cultures of chronic myelogenous leukemic patients with antibodies specific for GPIIIa or GPIIb demonstrated the existence of a pro-GPIIb-GPIIIa complex and of a large pool (60%) of unassociated GPIIIa; nearly all the GPIIb and the pro-GPIIb molecules were found associated with GPIIIa. This free GPIIIa was not exposed on the cell surface. Pulse-chase experiments on a subclone of the human megakaryocytic cell line LAMA-84 revealed that the cells from this subclone produced only the pro-GPIIb, which was neither processed into mature GPIIb nor expressed on the cell surface. The expression of GPIIIa in PMA treated cells result...
Research Interests:
The platelet glycoprotein GPIIb/IIIa and the vitronectin receptor (VNR) are alpha beta-heterodimeric proteins and share the same beta-subunit. By performing swainsonine treatment and digestion with endoglycosidase H (Endo H), we showed... more
The platelet glycoprotein GPIIb/IIIa and the vitronectin receptor (VNR) are alpha beta-heterodimeric proteins and share the same beta-subunit. By performing swainsonine treatment and digestion with endoglycosidase H (Endo H), we showed that the heavy chains of GPIIb and VNR alpha are glycosylated by complex-type oligosaccharide chains, and provided the first evidence for the presence of one complex carbohydrate residue on their light chains. The proteolytic cleavage of pro-GPIIb and the acquisition of Endo H-resistance are independent events occurring in the same Golgi compartment. We demonstrated the Endo H-sensitivity of GPIIIa and VNR beta in all cellular systems tested. In addition, this beta-subunit is differently glycosylated according to whether it is associated with GPIIb or VNR alpha, one carbohydrate chain being processed to the complex type on GPIIIa, but not on VNR beta.
Research Interests:
Research Interests:
... w/links (466 KB). Chapter 11. Cancer Immune System Competition Nicola Bellomo, Maria Letizia Bertotti, Santo Motta Abstract - Hi-Res PDF (536 KB) - PDF w/links (544 KB). Chapter 12. Analysing Hypersensitivity to Chemotherapy ...
Research Interests:
Cell adhesive and rheological properties play a very important role in cell transmigration through the endothelial barrier, in particular in the case of inflammation (leukocytes) or cancer metastasis (cancer cells). In order to... more
Cell adhesive and rheological properties play a very important role in cell transmigration through the endothelial barrier, in particular in the case of inflammation (leukocytes) or cancer metastasis (cancer cells). In order to characterize cell viscoelastic properties, we have designed a force spectrometer (AFM) which can stretch cells thereby allowing measurement of their rheological properties. This custom-made force spectrometer allows two different visualizations, one lateral and one from below. It allows investigation of the effects of rheology involved during cell stretching. To test the ability of our system to characterize such viscoelastic properties, ICAM-1 transfected CHO cells were analyzed. Two forms of ICAM-1 were tested; wild type ICAM-1, which can interact with the cytoskeleton, and a mutant form which lacks the cytoplasmic domain, and is unable to associate with the cytoskeleton. Stretching experiments carried out on these cells show the formation of long filaments...
Research Interests: Biomedical Engineering, Rheology, Biorheology, Cell Adhesion, Atomic Force Microscopy, and 13 moreAdhesion, Cytoskeleton, Elasticity, Cellular mechanotransduction, AFM, Animals, Microrheology, Viscosity, Single Cell, Clinical Sciences, Rheological properties, Mechanical Stress, and Viscoelastic Properties
Research Interests:
Research Interests:
Research Interests:
Prostaglandin (PGE2, PGF2 alpha) production by bovine fasciculo-reticulata adrenocortical cell suspensions was examined using specific radioimmunoassay procedures. No detectable PGs (greater than 50 pg) could be measured in the extract... more
Prostaglandin (PGE2, PGF2 alpha) production by bovine fasciculo-reticulata adrenocortical cell suspensions was examined using specific radioimmunoassay procedures. No detectable PGs (greater than 50 pg) could be measured in the extract from up to 2 x 10(6) cell incubations after 1 h, with or without the presence of ACTH, although these cells expressed full steroidogenic capabilities under these conditions. The same preparations could produce PGs when supplemented with arachidonic acid but ACTH had no effect on this process. These negative findings could not be explained by analytical artifacts or metabolic transformation. However, an active PG synthetase system was characterized in bovine adrenocortical subcellular preparations. This system converted arachidonate and endogenous substrate(s) to PGE2 as the major product. No thromboxane or prostacyclin pathways were detected even at high enzyme/substrate ratio. Although the microsomal adrenal cortex PG synthetase activity shares many features with those observed in other tissues (Km = 8.3 x 10(-5) M, optimal pH at 8.0, stimulation of PGE2 formation in the presence of glutathione and L-epinphrine), its specific activity was comparatively low (Vmax = 2.5 ng PGE2/min/mg microsomal proteins), which may explain our negative findings using cell suspensions. These findings do not provide evidence to support the hypothesis proposing a role of endogenous PGs in the mechanism of acute ACTH action in the case of bovine adrenal cortex.
Research Interests:
Research Interests:
ABSTRACT
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Platelet membrane glycoprotein IIb-IIIa forms a calcium-dependent heterodimer and constitutes the fibrinogen receptor on stimulated platelets. GPIIb is a two-chain protein containing disulfide-linked alpha and beta subunits. GPIIIa is a... more
Platelet membrane glycoprotein IIb-IIIa forms a calcium-dependent heterodimer and constitutes the fibrinogen receptor on stimulated platelets. GPIIb is a two-chain protein containing disulfide-linked alpha and beta subunits. GPIIIa is a single chain protein. These proteins are synthesized in the bone marrow by megakaryocytes, but the study of their synthesis has been hampered by the difficulty in obtaining enriched population of megakaryocytes in large numbers. To examine the biosynthesis and processing of GPIIb-IIIa, purified human megakaryocytes were isolated from liquid cultures of cryopreserved leukocytes stem cell concentrates from patients with chronic myelogenous leukemia. Immunoprecipitation of [35S]methionine pulse-chase-labeled cell extracts by antibodies specific for the alpha or beta subunits of GPIIb indicated that GPIIb was derived from a precursor of Mr 130,000 that contains the alpha and beta subunits. This precursor was converted to GPIIb with a half-life of 4-5 h. No precursor form of GPIIIa was detected. The glycosylation of GPIIb-IIIa was examined in megakaryocytes by metabolic labeling in the presence of tunicamycin, monensin, or treatment with endoglycosidase H. The polypeptide backbones of the GPIIb and the GPIIIa have molecular masses of 120 and 90 kD, respectively. High-mannose oligosaccharides are added to these polypeptide backbones co-translationally. The GPIIb precursor is then processed with conversion of high-mannose to complex type carbohydrates yielding the mature subunits GPIIb alpha (Mr 116,000) and GPIIb beta (Mr 25,000). No posttranslational processing of GPIIIa was detected.