Yamane Kenichi, Ihn Hironobu, Kubo Masahide, Tamaki Kunihiko
University of Tokyo, Tokyo, Japan.
Arthritis Rheum. 2002 Sep;46(9):2421-8. doi: 10.1002/art.10477.
To investigate the molecular mechanism of the overexpression of transforming growth factor beta receptors (TGF(beta)Rs) in dermal fibroblasts from patients with systemic sclerosis (SSc).
Dermal fibroblasts from 7 patients with diffuse SSc of recent onset and from 7 healthy individuals were studied. The expression of TGF(beta)R type I (TGF(beta)RI), TGF(beta)RII, and type I collagen proteins in dermal fibroblasts was determined by immunoblotting. TGF(beta)RI, TGF(beta)RII, and alpha2(I) collagen messenger RNA (mRNA) were evaluated by Northern blot analysis. The transcriptional activities of the TGF(beta)RI and TGF(beta)RII genes were examined by luciferase assay.
SSc fibroblasts expressed increased levels of TGF(beta)RI and TGF(beta)RII protein and mRNA, as well as increased levels of type I collagen protein and alpha2(I) collagen mRNA. Moreover, the half-lives of TGF(beta)RI and TGF(beta)RII mRNA in SSc fibroblasts did not change compared with those in control dermal fibroblasts. The promoter activities of the TGF(beta)RI and TGF(beta)RII genes were both significantly increased in SSc fibroblasts compared with those in control fibroblasts. Calphostin C, a specific inhibitor of protein kinase C (PKC), inhibited TGF(beta)RI promoter activity in SSc fibroblasts, and LY294002, an inhibitor of phosphoinositide 3-kinase (PI 3-kinase), inhibited TGF(beta)RII promoter activity in SSc fibroblasts. Moreover, calphostin C and LY294002 inhibited the up-regulation of TGF(beta)RI and TGF(beta)RII mRNA, respectively, in SSc fibroblasts.
These results suggest that increased levels of TGF(beta)Rs in SSc fibroblasts play a role in excessive collagen production, and that up-regulation of TGF(beta)R expression might occur at the transcriptional levels. PKC and/or PI 3-kinase might contribute to the up-regulation of TGF(beta)R expression in SSc fibroblasts.
研究系统性硬化症（SSc）患者真皮成纤维细胞中转化生长因子β受体（TGFβRs）过表达的分子机制。
对7例近期发病的弥漫性SSc患者和7名健康个体的真皮成纤维细胞进行研究。通过免疫印迹法测定真皮成纤维细胞中I型TGFβ受体（TGFβRI）、II型TGFβ受体（TGFβRII）和I型胶原蛋白的表达。通过Northern印迹分析评估TGFβRI、TGFβRII和α2（I）胶原蛋白信使核糖核酸（mRNA）。通过荧光素酶测定法检测TGFβRI和TGFβRII基因的转录活性。
SSc成纤维细胞中TGFβRI和TGFβRII蛋白及mRNA水平升高，I型胶原蛋白和α2（I）胶原蛋白mRNA水平也升高。此外，与对照真皮成纤维细胞相比，SSc成纤维细胞中TGFβRI和TGFβRII mRNA的半衰期没有变化。与对照成纤维细胞相比，SSc成纤维细胞中TGFβRI和TGFβRII基因的启动子活性均显著增加。蛋白激酶C（PKC）的特异性抑制剂钙泊三醇C抑制SSc成纤维细胞中TGFβRI启动子活性，磷脂酰肌醇3激酶（PI 3激酶）抑制剂LY294002抑制SSc成纤维细胞中TGFβRII启动子活性。此外，钙泊三醇C和LY294002分别抑制SSc成纤维细胞中TGFβRI和TGFβRII mRNA的上调。
这些结果表明，SSc成纤维细胞中TGFβRs水平升高在胶原蛋白过度产生中起作用，且TGFβR表达上调可能发生在转录水平。PKC和/或PI 3激酶可能促成SSc成纤维细胞中TGFβR表达上调。
