Résumé :
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Communication n° 492. Muller cells, the main glial cell type of the retina rely on interactions with extracellular matrix (ECM) molecules for the maintenance of their morphology and functions, Among the ECM molecules, laminin-1 is abundant in the inner limiting membrane and around blood vessels.A possible link between laminin-1 and Muller cells is provided by the dystrophin-glycoprotein complex (DGC), whose members, such as Dp71, utrophin and dystroglycan, are expressed by Muller cells. A two-dimensional in vitro motility assay based on computer-controlled videomicroscopy and statistical analysis of cellular trajectories was used to charaterize the motility of cultured Muller cells on different (non-coated, laminin-coated, laminin+inhibitor-coated) surfaces Cell velocity, diffusion index (a measure of direction-changing frequency). and process dynamism were calculated. To evalute the role of the DGC-laminin interaction in the above processes either the function blocking antibody IIH6 against the extracellular dystroglycan subunit or heparin, known to mask the dystroglycan binding site on laminin-1, have been applyed. Laminin-1 increases motility and path-searching (direction-changing)activity of Muller cells in vitro, with a simultaneous enhancment in the cells' process formation/withdrawal dynamism. This indicates a functional relationship between laminin-1 and Muller glial cells. Inhibition of binding of laminin-1 to the DGC, by either IIH6, a -dystroglycan, or by masking of?function-blocking monoclonal antibody of -dystroglycan binding site by heparin led to a significant decrease?laminin-1's in the ability of laminin-1 to stimulate cell migration, while laminin-1-dependent increase in process dynamism and direction-changing activity remained unchanged DGC appears to be involved in the complex regulation of cell velocity during Muller cell migration while process dynamism and directional stability seems to be regulated independently of the above complex.
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