Ligand occupancy of the alpha-V-beta3 integrin is necessary for smooth muscle cells to migrate in response to insulin-like growth factor.
- 19 March 1996
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 93 (6) , 2482-2487
- https://doi.org/10.1073/pnas.93.6.2482
Abstract
Smooth muscle cells (SMCs) have been shown to migrate in response to insulin-like growth factor I (IGF-I). However, the mechanism mediating this response has not been determined. The migration rates of porcine and human vascular SMCs were assessed in a monolayer wounding assay. IGF-I and IGF-II induced increases of 141% and 97%, respectively, in the number of cells that migrated in 4 days. The presence of 0.2% fetal bovine serum in the culture medium was necessary for the IGFs to stimulate migration over uncoated plastic surfaces. However, if vitronectin was used as the substratum, IGF-I stimulated migration by 162% even in the absence of serum. To determine the role of integrins in mediating this migration, SMC surface proteins were labeled with 125I and immunoprecipitated with specific anti-integrin antibodies. Integrins containing alpha-V (vitronectin receptor), alpha5 (fibronectin receptor), and alpha3 (collagen/laminin receptor) subunits were the most abundant. IGF-I treatment caused a 73% reduction in alpha5-integrin subunit protein and a 25% increase in alpha-V subunit. More importantly, ligand binding of alpha-V-beta3 was increased by 2.4-fold. We therefore examined whether the function of the alpha-V-beta3 integrin was important for IGF-I-mediated migration. The disintegrin kistrin was shown by affinity crosslinking to specifically bind with high affinity to alpha-V-beta3 and not to alpha5-beta1 or other abundant integrins. The related disintegrin echistatin specifically inhibited 125I-labeled kistrin binding to alpha-V-beta3, while a structurally distinct disintegrin, decorsin, had 1000-fold lower affinity. The addition of increasing concentrations of either kistrin or echistatin inhibited IGF-I-induced migration, whereas decorsin had a minimal effect. The potency of these disintegrins in inhibiting IGF-I-induced migration paralleled their apparent affinity for the alpha-V integrin. Furthermore, an alpha-V-beta3 blocking antibody inhibited SMC migration by 80%. In summary, vitronectin receptor activation is a necessary component of IGF-I-mediated stimulation of smooth muscle migration, and alpha-V-beta3 integrin antagonists appear to be important reagents for modulating this process.Keywords
This publication has 31 references indexed in Scilit:
- The adhesive and migratory effects of osteopontin are mediated via distinct cell surface integrins. Role of alpha v beta 3 in smooth muscle cell migration to osteopontin in vitro.Journal of Clinical Investigation, 1995
- Association of insulin receptor substrate-1 with integrinsScience, 1994
- Insulin-like growth factor-I and platelet-derived growth factor-BB induce directed migration of human arterial smooth muscle cells via signaling pathways that are distinct from those of proliferation.Journal of Clinical Investigation, 1994
- Regulation of Fibroplasia in Cutaneous Wound RepairThe Lancet Healthy Longevity, 1993
- Extracellular matrix contains insulin-like growth factor binding protein-5: potentiation of the effects of IGF-I.The Journal of cell biology, 1993
- Integrin beta 1- and beta 3-mediated endothelial cell migration is triggered through distinct signaling mechanisms.The Journal of cell biology, 1993
- Differential modulation of vascular cell integrin and extracellular matrix expression in vitro by TGF‐β1 correlates with reciprocal effects on cell migration+Journal of Cellular Physiology, 1992
- Regulation of vascular smooth muscle cell integrin expression by transforming growth factor β1 and by platelet‐derived growth factor‐BBJournal of Cellular Physiology, 1992
- β1 And β3 integrins have different roles in the adhesion and migration of vascular smooth muscle cells on extracellular matrixExperimental Cell Research, 1992
- Stimulatory effects of insulin and insulin-like growth factor I on migration and tube formation by vascular endothelial cellsAtherosclerosis, 1992