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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, METHODS, RESULTS. Meshes: Animals, Calcium-Calmodulin-Dependent Protein Kinases, Cattle, Cell Adhesion Molecules, Cells, Cultured, Chemotaxis, Dose-Response Relationship, Drug, Focal Adhesion Protein-Tyrosine Kinases, Mitogen-Activated Protein Kinase 1, Mitogen-Activated Protein Kinase 3, Mitogen-Activated Protein Kinases, Muscle, Smooth, Vascular, Protein-Tyrosine Kinases, Thrombospondin 1.
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Is thrombospondin-1 regulation of smooth muscle cell chemotaxis extracellular signal-regulated protein kinases 1/2 dependent? Context: Thrombospondin-1 (TSP-1), an extracellular matrix protein, induces vascular smooth muscle cell (VSMC) chemotaxis. We hypothesized that extracellular signal-regulated protein kinases 1/2 (ERK1/2), a pathway of the mitogen activated protein kinase (MAPK) family, is important in TSP-1-induced VSMC chemotaxis. A modified Boyden chamber was used to assess chemotaxis. First, a concentration curve was performed to determine the level for optimal TSP-1-induced chemotaxis. Then quiescent VSMCs were preincubated (30 minutes) in serum-free medium, dimethyl sulfoxide (the inhibitor vehicle), or PD98059 (10 mumol/L, an upstream inhibitor of ERK1/2). VSMCs (50,000 cells/well) with the appropriate preincubation were placed in the top chamber. The bottom chamber contained TSP-1 (20 micrograms/mL) or serum-free medium. Results were recorded as cells/5 fields (400x). Then quiescent VSMCs were exposed to TSP-1 (20 micrograms/mL) for 0, 1, 5, 10, 30, 120, or 300 minutes. Platelet-derived growth factor (10 ng/mL) was the positive control for ERK1/2 activation. Western blot analysis was performed for activated ERK1/2. All comparisons were made by a paired t test (n = 3). TSP-1-induced chemotaxis peaks by a concentration of 20 micrograms/mL. PD98059 inhibited TSP-1-induced chemotaxis (P < .05). ERK1/2 was activated by TSP-1-stimulated VSMCs.
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TSP-1-stimulated VSMCs activated ERK1/2. An ERK1/2 inhibitor abolished chemotaxis, suggesting the functional importance of MAPK in TSP-1-induced VSMC chemotaxis. Final Decision: yes