Mesenchymal cell migration in association with matrix production and the reorganization of secreted fibrillar protein networks, all contribute to regional tissue remodeling with the potential of lesion formation in the vascular wall. The experimental approach in this proposal is designed to yield fundamental knowledge regarding the cell surface heparin sulfate proteoglycan, syndecan 4, which is an important molecular determinant modulating cell migration and matrix remodeling. Specifically, the investigators intend to: 1) Define the role of syndecan 4 in modulating vascular smooth muscle cell migration speed and directional persistence. This series of experiments will define the ability of syndecan 4 to modulate cell speed, directional persistence, and the commitment of cells to a motile phenotype in both the presence and absence of heparin sulfate binding chemoattractants. Specifically, motility behavior will be analyzed using time-lapse epifluorescence videomicroscopy in association with computational techniques and mathematical formulations. 2) Characterize the ability of syndecan 4 to influence integrin dependent cell/substrate adhesive behavior. The kinetics and magnitude of cell-substrate binding strength will be investigated in defined cell lines and on model substrates utilizing a differential centrifugation assay. These biophysical studies will be correlated with time-dependent immunofluorescence microscopy studies of cell morphology and matrix reorganization. Together these investigations will allow us to understand how syndecan 4 can influence motility by its effect on cell-substrate adhesion. 3) Identify the role of syndecan 4 in governing cell traction forces and vascular smooth muscle cell mediated matrix remodeling. The generation of cell traction forces and matrix remodeling will be studied in fibrin and collagen microspheres populated with variant cell lines. Mathematical models will be used to characterize changes in cell traction as a function of perturbations in the experimental system. Using these analytical tools, traction mediated effects will be investigated independently of other potentially important variables in the remodeling process, such as cell growth, matrix mechanical properties, and tissue geometry.
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