Study of Cross‐Talk in Signal Transduction Pathways Using a Novel High‐Throughput Measurement System

The coordinated movement of cells is fundamental to many physiologic processes including tissue inflammation, repair and fibrosis. Extracellular and intracellular signals contribute to organized cell migration by modulating actin polymerization and myosin‐dependent contraction. Using 3D tissue constructs and a novel high‐throughput measurement system we investigated actin polymerization and cell contraction in rat fibroblasts treated with platelet‐derived growth factor (PDGF) and lysophosphatidic acid (LPA). Both are mitogenic factors influencing cytoskeletal reorganization via distinct but interrelated signaling pathways. We hypothesize that PDGF and LPA activate common signaling molecules and cross‐talk between the signaling pathways impacts cell migration. We demonstrated that PDGF treatments (1 – 250 ng/ml) alone increased contraction in a concentration‐dependent manner, but when combined with LPA (1–50 μM) displayed a bell‐shaped response curve with maximal contraction at 1–25 ng/ml PDGF. In addition, the degree of cell spreading showed a bell‐shaped response to PDGF treatment (peak at 1–25 ng/ml) with and without LPA treatment. Our method provides rapid analysis of tissue responses to numerous combinations of PDGF and LPA, which is an important first step in the evaluation of cross‐talk between signaling pathways that regulate cell migration.