Lysophosphatidic acid inhibits TGF-h-mediated stimulation of type I collagen mRNA stability via an ERK-dependent pathway in dermal fibroblasts Madoka Sato a, * , Daniel Shegogue b , Atsushi Hatamochi a , Soji Yamazaki a , Maria Trojanowska b a Department of Dermatology, Dokkyo University School of Medicine, Mibu, Tochigi, 321-0293, Japan b Division of Rheumatology and Immunology, Department of Medicine, Medical University of South Carolina, Charleston, SC, USA Received 17 March 2004; received in revised form 21 July 2004; accepted 22 July 2004 Abstract Lysophosphatidic acid (LPA) is a serum-derived pleiotropic mediator with a potential role in wound repair. Since extracellular matrix (ECM) deposition is a critical part of wound healing, this study was designed to examine whether LPA is involved in ECM regulation. Using human dermal fibroblasts, we demonstrate that LPA counteracts transforming growth factor-h (TGF-h) stimulation of type I collagen mRNA and protein. This factor elicits its inhibitory effects at the posttranscriptional level via destabilization of type I collagen mRNA. Furthermore, using the mitogen-activated protein kinase kinase (MEK) inhibitor PD98059, we show that the extracellular signal-regulated kinase (ERK) pathway is a negative regulator of the TGF-h-induced stabilization of type I collagen mRNA, and that the activation of the ERK pathway by LPA mediates their inhibitory effects on collagen production. In conclusion, this study describes a novel function for LPA as an antagonist of TGF-h induced ECM deposition. These findings may be relevant to physiologic wound repair and may be useful in designing therapeutic agents to prevent excessive scarring. D 2004 Elsevier B.V./International Society of Matrix Biology. All rights reserved. Keywords: Lysophosphatidic acid; Extracellular signal-regulated kinase; Transforming growth factor-h; mRNA stability; Type I collagen; Extracellular matrix 1. Introduction Type I collagen, the major collagen in the body, consists of two a1(I) chains and one a2(I) chain which are coordinately regulated (Vuorio and de Crombrugghe, 1990; Ramirez and Di Liberto, 1990). The excessive deposition of collagen type I and other extracellular matrix (ECM) proteins, which occurs in fibrotic diseases such as pulmonary fibrosis, liver cirrhosis, glomerular sclerosis, and scleroderma, leads to organ dysfunction and failure. The regulation of type I collagen gene expression in healthy tissues during develop- ment and wound healing and its dysregulation in fibrosis has been the subject of intense studies. Transforming growth factor-h (TGF-h) is currently considered the main stimulus of ECM production, while other cytokines, including connective tissue growth factor (CTGF) and interleukin-4 (IL-4) may also contribute to elevated collagen deposition (Trojanowska et al., 1998; Slack et al., 1993). Tumor necrosis factor-a (TNF-a) and interferon-g (INF-g) antagonize the effects of TGF-h with respect to collagen production (Ka ¨ha ¨ri et al., 1990; Kouba et al., 1999; Greenwel et al., 2000; Verrecchia and Mauviel, 2002). TGF-h stimulates type I collagen gene expression by transcriptional and post-tran- scriptional mechanisms (Raghow et al., 1987; Pettinen et al., 1988; Eckes et al., 1996). A number of transcription factors involved in basal and cytokine-regulated type I collagen gene expression have been characterized (Ihn et al., 1996; Chen et al., 1999; Trojanowska, 2002; Ghosh, 2002). There is also evidence that increased collagen mRNA stability plays a role in collagen upregulation in activated hepatic stellate cells and scleroderma fibroblasts (Eckes et al., 1996; Stefanovic et al., 1997), however, relatively little is known about the molecular mechanisms regulating the turnover of collagen mRNA. 0945-053X/$ - see front matter D 2004 Elsevier B.V./International Society of Matrix Biology. All rights reserved. doi:10.1016/j.matbio.2004.07.005 * Corresponding author. Tel.: +81 282 86 1111; fax: +81 282 86 3470. E-mail address: satomad@excite.co.jp (M. Sato). Matrix Biology 23 (2004) 353 – 361 www.elsevier.com/locate/matbio