Dubaybo B A, Thet L A
Veterans Administration Medical Center, Allen Park, Michigan 48101.
Exp Lung Res. 1990 Sep-Oct;16(5):389-403. doi: 10.3109/01902149009068816.
The processes of lung growth, injury, and repair are characterized by alterations in fibroblast synthesis and interstitial distribution of extracellular matrix components. Transforming growth factor beta (TGF-beta), which is postulated to play a role in modulating lung repair, alters the distribution of several matrix components such as collagen and fibronectin. We studied the effect of TGF-beta on the synthesis and distribution of the various glycosaminoglycans (GAGs) and whether these effects may explain its role in lung repair. Human diploid lung fibroblasts (IMR-90) were exposed to various concentrations of TGF-beta (0-5 nM) for variable periods of time (0-18 h). Newly synthesized GAGs were labeled with either [3H]glucosamine or [35S]sulfate. Individual GAGs were separated by size exclusion chromatography after serial enzymatic and chemical digestions and quantitated using scintillation counting. There was a dose-dependent increase in total GAG synthesis with maximal levels detected after 6 h of exposure. This increase was noted in all individual GAG types measured and was observed in both the cell associated GAGs (cell-matrix fraction) as well as the GAGs released into the medium (medium fraction). In the cell-matrix fraction, TGF-beta increased the proportion of heparan sulfate that was membrane bound as well as the proportion of dermatan sulfate in the intracellular compartment. In the medium fraction, TGF-beta increased the proportion of hyaluronic acid, chondroitin sulfate and dermatan sulfate released. We conclude that the role of TGF-beta in lung growth and repair may be related to increased synthesis of GAGs by human lung fibroblasts as well as alterations in the distribution of individual GAGs.
肺的生长、损伤和修复过程的特征是成纤维细胞合成及细胞外基质成分的间质分布发生改变。据推测，转化生长因子β（TGF-β）在调节肺修复中发挥作用，它会改变几种基质成分如胶原蛋白和纤连蛋白的分布。我们研究了TGF-β对各种糖胺聚糖（GAGs）合成和分布的影响，以及这些影响是否可以解释其在肺修复中的作用。将人二倍体肺成纤维细胞（IMR-90）暴露于不同浓度（0 - 5 nM）的TGF-β中不同时间（0 - 18小时）。用[3H]葡萄糖胺或[35S]硫酸盐标记新合成的GAGs。经过一系列酶解和化学消化后，通过尺寸排阻色谱法分离各个GAGs，并使用闪烁计数进行定量。总GAG合成呈剂量依赖性增加，暴露6小时后检测到最高水平。在所有测量的单个GAG类型中均观察到这种增加，并且在细胞相关GAGs（细胞 - 基质部分）以及释放到培养基中的GAGs（培养基部分）中均有观察到。在细胞 - 基质部分，TGF-β增加了膜结合硫酸乙酰肝素的比例以及细胞内硫酸皮肤素的比例。在培养基部分，TGF-β增加了透明质酸、硫酸软骨素和硫酸皮肤素释放的比例。我们得出结论，TGF-β在肺生长和修复中的作用可能与人类肺成纤维细胞GAGs合成增加以及单个GAGs分布改变有关。
