Dawes K E, Cambrey A D, Campa J S, Bishop J E, McAnulty R J, Peacock A J, Laurent G J
Centre for Respiratory Research, University College London Medical School, U.K.
Int J Biochem Cell Biol. 1996 Feb;28(2):229-38. doi: 10.1016/1357-2725(95)00124-7.
Endothelin-1 (Et-1) is a 21-amino acid peptide primarily synthesized by endothelial cells. It was originally classified as a potent vasoconstrictor but recent evidence suggests that it also possesses a wide variety of non-vascular actions. It stimulates fibroblast and smooth muscle cell proliferation and it has been shown to stimulate fibroblast collagen metabolism. However, studies on its ability to regulate collagen production remain incomplete, and its effect on post-translational processing of procollagen has not been studied. This report details the effect of Et-1 on the rates of procollagen synthesis and degradation in two fibroblast cell lines; human foetal lung (HFL-1) and whole foetal rat fibroblasts (Rat 2). Fibroblast cultures were incubated for 24 hr in the presence or absence of Et-1 before procollagen metabolism was determined by measuring hydroxyproline. Non-collagen metabolism was also determined in these cultures from the uptake of tritiated phenylalanine. Et-1 stimulated procollagen synthesis in HFL-1 fibroblasts and reduced synthesis in Rat 2 cells. The response was dose dependent with the greatest effect at 1.10(-6) M Et-1 for both cell types (155 +/- 6% of control (mean +/- SD, n = 6, P < 0.01) and 61 +/- 4% of control (n = 4, P < 0.01) for HFL-1 and Rat 2 fibroblasts, respectively). Non-collagen protein synthesis was increased to 148 +/- 5% of control (P < 0.05) at 1.10(-6) M Et-1. Non-collagen protein synthesis remained unaffected in the HFL-1 fibroblast cultures. Procollagen degradation, expressed as a proportion of total procollagen synthesis, was decreased in HFL-1 fibroblasts (control, 29 +/- 2%; Et-1, 1.10(-6) M; 21 +/- 2%; P < 0.01), and increased in Rat 2 fibroblasts (control 42 +/- 1%; Et-1, 1.10(-6) M; 49 +/- 1%; P < 0.01). Blocking of the EtA receptor for Et-1, using the receptor antagonist-BQ123, abolished the effect of Et-1 on procollagen metabolism in both cell types. These results suggest that different populations of fibroblasts exhibit heterogeneous responses to Et-1. It is concluded that Et-1 may play an important role in the extent and distribution of fibrosis seen in diseases associated with the overproduction of Et-1.
内皮素 -1（Et-1）是一种主要由内皮细胞合成的含21个氨基酸的肽。它最初被归类为一种强效血管收缩剂，但最近的证据表明它还具有多种非血管作用。它刺激成纤维细胞和平滑肌细胞增殖，并且已被证明能刺激成纤维细胞的胶原蛋白代谢。然而，关于其调节胶原蛋白产生能力的研究仍不完整，并且尚未研究其对前胶原蛋白翻译后加工的影响。本报告详细阐述了Et-1对两种成纤维细胞系（人胎儿肺成纤维细胞（HFL-1）和大鼠全胎儿成纤维细胞（Rat 2））中前胶原蛋白合成和降解速率的影响。在有或没有Et-1的情况下，将成纤维细胞培养物孵育24小时，然后通过测量羟脯氨酸来确定前胶原蛋白的代谢。还通过测量氚标记苯丙氨酸的摄取来确定这些培养物中的非胶原蛋白代谢。Et-1刺激HFL-1成纤维细胞中的前胶原蛋白合成，并降低Rat 2细胞中的合成。这种反应是剂量依赖性的，对于两种细胞类型，在1×10⁻⁶ M Et-1时效果最佳（HFL-1和Rat 2成纤维细胞分别为对照的155±6％（平均值±标准差，n = 6，P <0.01）和61±4％（n = 4，P <0.01））。在1×10⁻⁶ M Et-1时，非胶原蛋白合成增加至对照的148±5％（P <0.05）。在HFL-1成纤维细胞培养物中，非胶原蛋白合成保持不受影响。以前胶原蛋白合成总量的比例表示的前胶原蛋白降解在HFL-1成纤维细胞中降低（对照，29±2％；Et-1，1×10⁻⁶ M；21±2％；P <0.01），而在Rat 2成纤维细胞中增加（对照42±1％；Et-1，1×10⁻⁶ M；49±1％；P <0.01）。使用受体拮抗剂BQ123阻断Et-1的EtA受体，消除了Et-1对两种细胞类型中前胶原蛋白代谢的影响。这些结果表明，不同群体的成纤维细胞对Et-1表现出异质性反应。结论是，Et-1可能在与Et-1过度产生相关的疾病中所见纤维化的程度和分布中起重要作用。
