Protease-Activated Receptor-2 (PAR-2) Expression in Human Fibroblasts is Regulated by Growth Factors and Extracellular Matrix

• Published in: Journal of investigative dermatology Vol. 123; no. 5; pp. 832 - 839
• Main Authors: Gruber, Barry L., Marchese, Mary J., Santiago-Schwarz, Frances, Martin, Carla A., Zhang, Jianhua, Kew, Richard R.
• Format: Journal Article
• Language: English
• Published: Danvers, MA Elsevier Inc 01.11.2004; Nature Publishing; Elsevier Limited
• Subjects: Biological and medical sciences; Cells, Cultured; collagen; Dermatology; Extracellular Matrix - physiology; fibroblasts; Fibroblasts - cytology; Fibroblasts - physiology; fibrosis; Flow Cytometry; Gene Expression Regulation - drug effects; Humans; Immunoblotting; Medical sciences; PDGF; Platelet-Derived Growth Factor - pharmacology; protease activated receptors; Proto-Oncogene Proteins c-sis; Receptor, PAR-2 - genetics; Receptor, PAR-2 - metabolism; Transforming Growth Factor beta - pharmacology; collagen; fibroblasts; fibrosis; protease activated receptors; PDGF; Human; protease activated receptors/fibroblasts/fibrosis/PDGF/collagen; Regulation(control); Dermatology; Collagen; Fibrosis; PAR2 protease-activated receptor; Extracellular matrix; Protease-activated receptor; Fibroblast; Platelet derived growth factor; Growth factor
• ISSN: 0022-202X; 1523-1747
• DOI: 10.1111/j.0022-202X.2004.23445.x

Many cell types express a membrane receptor, activated by trypsin-like proteases, termed protease-activated receptor-2 (PAR-2). Previous studies describing PAR-2 expression on fibroblasts have been conflicting. In this report, we investigated in vitro PAR-2 expression on several fibroblast cell lines using flow cytometry, immunohistology, and immunoblots of cell lysates. Consistent PAR-2 expression was detected in cultured fibroblasts, although we observed heterogeneity of cellular expression among the cell lines. Some fibroblast lines expressed PAR-2 predominantly as an intracellular protein with differing cytoplasmic staining patterns, whereas other fibroblast lines displayed PAR-2 primarily as a cell surface receptor. Immunoblots of cell lysates with polyclonal anti-PAR-2 demonstrated a 44 kDa band, the predicted molecular weight for the PAR-2 core protein. Furthermore, we noted that expression of PAR-2 was subject to regulation. Fibroblasts grown within a collagen matrix downregulated receptor expression whereas increased PAR-2 expression was observed by the addition of fibroblast growth factors PDGF-BB and TGF-β. This study may explain the previous inconsistencies in PAR-2 expression observed on tissue fibroblasts. Results indicate that the degree of fibroblast proliferation, attenuated by extracellular matrix and upregulated by growth factors, influences whether fibroblasts express PAR-2 and, thus, would be responsive to protease signaling.