Wnt/beta-catenin pathway forms a negative feedback loop during TGF-beta 1 induced human normal skin fibroblast-to-myofibroblast transition

Background: Fibroblast-to-myofibroblast transition is a key event during wound healing and hypertrophic scar formation. Previous studies suggested Wnt/beta-catenin signaling might be involved in the wound healing. However, its specific role in skin fibroblast-to-myofibroblast transition remains unclear. Objective: To investigate the specific role of beta-catenin during the transforming growth factor-beta 1 induced normal skin myofibroblasts transition. Methods: By real-time quantitative polymerase chain reaction, Western-blot and immunocytochemistry, the activation of Wnt/beta-catenin pathway in cultured human normal skin fibroblasts during TGF-beta 1 induced fibroblast-to-myofibroblast transition was investigated. The effects of beta-catenin on myofibroblasts transition were also investigated when SB-216763, over-expression and siRNA of beta-catenin were utilized. In addition, fibroblasts populated collagen lattices contraction assays were conducted to examine the effects of beta-catenin on the contractility of the fibroblasts induced by TGF-beta 1. Furthermore, the effects of beta-catenin on the expression of alpha-smooth muscle actin and collagen types I and III in hypertrophic scar derived fibroblasts were studied. Results: The expression of Wnts mRNA and beta-catenin protein was up-regulated by TGF-beta 1 stimulation during the myofibroblasts transition. Both of SB-216763 and beta-catenin over-expression was paralleled with decreased expression of alpha-smooth muscle actin, collagen types land III, while siRNA targeting beta-catenin leads to up-regulation of alpha-smooth muscle actin, collagen types I and III. The increased contractility and alpha-smooth muscle actin expression of the fibroblasts in the collagen lattices induced by TGF-beta 1 was inhibited by SB-216763. In addition, the expression levels of alpha-smooth muscle actin, collagen types I and III in hypertrophic scar derived fibroblasts were also down-regulated by SB-216763. Conclusion: Specifically in normal skin fibroblasts, beta-catenin might be involved in the myofibroblasts transition and negatively regulate the TGF-beta 1-induced myofibroblast transition. (C) 2011 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.