CTGF Stimulation of Collagen Production in Scleroderma

硬皮病或系统性硬化症（SSc）的主要表现之一是过度产生结缔组织基质，损害皮肤和多个内脏器官的功能。虽然这种疾病的致病机制很复杂且不完全清楚，但结缔组织的许多有害方面很可能是由tgf - β作为最终共同途径的多种作用介导的。强有力的证据表明，tgf - β对成纤维细胞细胞外基质的许多作用可能是由结缔组织生长因子（CTGF）介导的。我们的初步数据表明，培养的SSC和正常成纤维细胞中CTGF的表达受到tgf - β的极大刺激，我们通过免疫定位证实了SSC患者真皮中存在过量的CTGF。我们提出以下假设：(1)tgf - β刺激CTGF表达，除了Smads外，还需要戊酰化蛋白(s)和蛋白激酶C （PKC）的活性。(2) CTGF是纤维增殖反应的主要介质，通过与整合素细胞表面受体结合发挥活性。(3) CTGF表达和/或活性调控的改变是SSc致病性纤维化反应的一个重要特征。为了验证这些假设，我们提出以下目标：(1)确定和表征tgf - β刺激正常和SSC成纤维细胞中CTGF表达的分子机制。(2)明确CTGF在正常和SSC成纤维细胞中增加胶原表达的信号通路。(3)鉴定并表征COLIA1基因启动子中CTGF顺式响应元件及其同源交易因子。确定CTGF的作用机制及其表达调控途径具有相当重要的意义，因为CTGF可能在SSC的发病机制中发挥关键作用，阻断其异常产生可能改善纤维化反应中最有害的特征。

One of the cardinal manifestations of Scleroderma or Systemic Sclerosis (SSc) is excessive production of connective tissue matrix which impairs function in the skin and multiple internal organs. While the pathogenic mechanisms underlying this disease are complex and incompletely understood, it is likely that many of the harmful aspects with respect to connective tissue are mediated by the manifold effects of TGF-beta acting as a final common pathway. Strong evidence suggests that many of the effects of TGF-beta on fibroblast extracellular matrix may be mediated by connective tissue growth factor (CTGF) Our preliminary data demonstrate that CTGF expression by cultured SSC and normal fibroblasts is greatly stimulated by TGF-beta1 aqnd we have confirmed the presence of excess CTGF in the dermis of SSc patients by immunolocalization. We pose the following hypotheses: (1) TGF-beta stimulation of CTGF expression requires the activity of prenylated protein(s) and protein kinase C (PKC) in addition to the Smads. (2) CTGF is a major mediator of the fibroproliferative response, exerting its activity through binding to integrin cell surface receptor(s). (3) Alteration in the regulation of CTGF expression and/or its activity is a significant feature of the pathogenic fibrotic response found in SSc. In order to test these hypotheses, we propose the following aims: (1) To identify and characterize the molecular mechanisms whereby TGF-beta stimulates expression of CTGF in normal and SSC fibroblasts. (2) To define the signaling pathways whereby CTGF increases expression of collagen in normal and SSC fibroblasts. (3) To identify and characterize CTGF cis- responsive elements in the promoter of the COLIA1 gene and their cognate transacting factors. Identification of the mechanisms of action of CTGF and the pathways regulating its expression are of considerable importance, since CTGF may play a key role in the pathogenesis of SSC and blocking its abnormal production may ameliorate the most harmful features of the fibrotic response.