Migration of fibroblasts plays an essential role in tissue repair after injury. Sphingosine 1-phosphate (S1P) is a multifunctional mediator released by many cells that can be released in inflammation and after injury. This study evaluated the effect of S1P on fibroblast chemotaxis toward fibronectin. S1P alone did not affect fibroblast migration, but S1P enhanced fibronectin-directed chemotaxis in a concentrationdependent manner. The effect of S1P was not mimicked by dihydro (dh) S1P or the S1P 1 receptor agonist SEW2871. S1P augmentation of fibroblast chemotaxis, however, was completely blocked by JTE-013, an S1P 2 antagonist, but not by suramin, an S1P 3 antagonist. Suppression of the S1P 2 receptor by small interfering (si)RNA also completely blocked S1P augmentation of fibroblast chemotaxis to fibronectin. S1P stimulated Rho activation and focal adhesion kinase (FAK) phosphorylation, and these were also significantly inhibited by the S1P 2 receptor antagonist (JTE-013) or by S1P 2 siRNA. Further, the potentiation of S1P signaling was blocked by the Rho-kinase inhibitor Y-27632 in a concentration-dependent manner. Inhibition of FAK with siRNA reduced basal chemotaxis toward fibronectin slightly but significantly, and almost completely blocked S1P augmented chemotaxis. These results suggest that S1P-augmented fibroblast chemotaxis toward fibronectin depends on the S1P 2 receptor and requires Rho and Rho-kinase, and FAK phosphorylation. By augmenting fibroblast recruitment, S1P has the potential to modulate tissue repair after injury. The pathways by which S1P mediates this effect, therefore, represent a potential therapeutic target to affect tissue repair and remodeling.
The ability of fibroblasts to contract three-dimensional collagen gels has been used as an in vitro model of the tissue contraction which characterises both normal repair and fibrosis. Among its actions, thrombin can activate the protease-activated receptor (PAR)1 and, thereby, stimulate inflammation and repair. The current study evaluated whether thrombin could stimulate fibroblast-mediated collagen gel contraction by activating PAR1 and whether its downstream signalling depends on protein kinase C (PKC)-e.Human foetal lung fibroblasts (HFL-1) were cultured in three-dimensional collagen gels and the area of the gels was measured by image analyser.Both thrombin and TFLLR, a selective PAR1 agonist, stimulated collagen gel contraction mediated by HFL-1. After RNA interference-mediated PAR1 knockdown in HFL-1, both thrombin and the PAR1 agonist-induced gel contraction were partially inhibited (by 22.4¡2.2% and 17.6¡5.6%, respectively). The gel contraction stimulated by thrombin was also reduced by a nonspecific PKC inhibitor and a calciumindependent PKC-e inhibitor. Both thrombin and TFLLR significantly increased PKCe activity, and this effect was blocked by PAR1 knockdown.Thrombin stimulates collagen gel contraction at least partially through activation of protease-activated receptor 1 and protein kinase C-e, and may contribute to tissue remodelling in inflammatory airway and lung diseases. Eur Respir J 2004; 24: 918-924.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.