β1 integrin-extracellular matrix protein interaction modulates the migratory response to chemokine stimulation
It is well established that chemokines have a major role in the stimulation of cell movement on extracellular matrix (ECM) substrates. However, it is also clear that ECM substrates may influence the ability of cells to undergo migration. Using the migration chamber method, we assessed the migratory response of human embryonic kidney-293 (HEK) transfectant cells expressing the CC chemokine receptor 5 (CCR5) (HEK-CCR5) to stimulation by chemokines (macrophage inflamatory protein (MIP)-1α, MIP-1β, and regulated on activation normal-T cell expressed and secreted (RANTES)) on ECM substrates (collagen type I and fibronectin). Using filters coated with collagen (20 µg/mL), results showed that the chemokines differed in their ability to elicit cell movement according to the order MIP-1β > RANTES [Formula: see text] MIP-1α. In contrast, using filters coated with fibronectin (20 µg/mL), all three chemokines were similar in their ability to stimulate migration of HEK-CCR5 cells. In addition, the migratory response with respect to the concentrations of ECM substrates appeared biphasic; thus, chemokine-stimulated cell movement was inhibited at high ECM concentrations (100 µg/mL). To determine the involvement of β1 integrins, results showed that the migratory response to chemokine stimulation on collagen was largely inhibited by monoclonal antibody (mAb) to α2β1; however, complete inhibition required a combination of mAbs to α1β1 and α2β1. In comparison, migration on fibronectin was inhibited by mAb to α3β1 and α5β1. Our results suggest that the migratory response to CCR5 stimulation may vary quantitatively with both the CCR5 ligand (MIP-1α, MIP-1β, and RANTES), as well as the nature and concentration of the ECM substrate involved.Key words: chemokines, integrins, cell movement, extracellular matrix proteins, CCR5.