Sonnylal Sonali, Shi-Wen Xu, Leoni Patricia, Naff Katherine, Van Pelt Caroline S, Nakamura Hiroyuki, Leask Andrew, Abraham David, Bou-Gharios George, de Crombrugghe Benoit
Department of Genetics, University of Texas MD Anderson Cancer Center, Houston, TX 77030, USA.
Arthritis Rheum. 2010 May;62(5):1523-32. doi: 10.1002/art.27382.
Connective tissue growth factor (CTGF) is a cysteine-rich secreted matricellular protein involved in wound healing and tissue repair. Enhanced and prolonged expression of CTGF has been associated with tissue fibrosis in humans. However, questions remain as to whether CTGF expression alone is sufficient to drive fibrosis. This study was undertaken to investigate whether CTGF alone is sufficient to cause fibrosis in intact animals and whether its effects are mediated through activation of transforming growth factor beta (TGFbeta) signaling or through distinct signal transduction pathways.
We generated mice overexpressing CTGF in fibroblasts under the control of the fibroblast-specific collagen alpha2(I) promoter enhancer. Tissues such as skin, lung, and kidney were harvested for histologic analysis. Mouse embryonic fibroblasts were prepared from embryos (14.5 days postcoitum) for biochemical analysis.
Mice overexpressing CTGF in fibroblasts were susceptible to accelerated tissue fibrosis affecting the skin, lung, kidney, and vasculature, most notably the small arteries. We identified a marked expansion of the myofibroblast cell population in the dermis. RNA analysis of transgenic dermal fibroblasts revealed elevated expression of key matrix genes, consistent with a fibrogenic response. CTGF induced phosphorylation of p38, ERK-1/2, JNK, and Akt, but not Smad3, in transgenic mouse fibroblasts compared with wild-type mouse fibroblasts. Transfection experiments showed significantly increased basal activity of the CTGF and serum response element promoters, and enhanced induction of the CTGF promoter in the presence of TGFbeta.
These results demonstrate that selective expression of CTGF in fibroblasts alone causes tissue fibrosis in vivo through specific signaling pathways, integrating cues from the extracellular matrix into signal transduction pathways to orchestrate pivotal biologic responses relevant to tissue repair and fibrosis.
结缔组织生长因子（CTGF）是一种富含半胱氨酸的分泌性基质细胞蛋白，参与伤口愈合和组织修复。CTGF表达的增强和延长与人类组织纤维化有关。然而，仅CTGF表达是否足以驱动纤维化仍存在疑问。本研究旨在调查单独的CTGF是否足以在完整动物中引起纤维化，以及其作用是否通过转化生长因子β（TGFβ）信号通路的激活或通过不同的信号转导途径介导。
我们构建了在成纤维细胞特异性胶原α2（I）启动子增强子控制下过表达CTGF的小鼠。收集皮肤、肺和肾等组织进行组织学分析。从胚胎（妊娠14.5天）制备小鼠胚胎成纤维细胞用于生化分析。
在成纤维细胞中过表达CTGF的小鼠易发生加速的组织纤维化，影响皮肤、肺、肾和脉管系统，最明显的是小动脉。我们发现真皮中成肌纤维细胞群体显著扩张。转基因真皮成纤维细胞的RNA分析显示关键基质基因表达升高，与纤维化反应一致。与野生型小鼠成纤维细胞相比，CTGF在转基因小鼠成纤维细胞中诱导p38、ERK-1/2、JNK和Akt磷酸化，但不诱导Smad3磷酸化。转染实验显示CTGF和血清反应元件启动子的基础活性显著增加，并且在存在TGFβ的情况下CTGF启动子的诱导增强。
这些结果表明，仅成纤维细胞中CTGF的选择性表达通过特定信号通路在体内引起组织纤维化，将细胞外基质的信号整合到信号转导通路中，以协调与组织修复和纤维化相关的关键生物学反应。
