Beavan L A, Quentin-Hoffmann E, Schönherr E, Snigula F, Leroy J G, Kresse H
Institute of Physiological Chemistry and Pathobiochemistry, University of Münster, Germany.
J Biol Chem. 1993 May 5;268(13):9856-62.
Fibroblasts from young patients exhibiting clinical features of progeroidal syndromes showed decreased biosynthesis of the small proteoglycan decorin. Cells in culture were metabolically labeled, and proteoglycans secreted into the medium were analyzed electrophoretically after immunoprecipitation with antibodies raised against decorin and biglycan. Fluorograms showed regularly a reduction to 15-30% of the normal amount of mature decorin and its core protein after chondroitin ABC lyase treatment. The size of the glycosaminoglycan chains was increased, but there was no obvious anomaly in the secretion kinetics of the mature proteoglycan. In addition, the patients' fibroblasts synthesized an increased amount of biglycan compared to control cells from healthy donors. Northern blot analysis clearly demonstrated a reduction by 85-94% in decorin mRNA, but biglycan mRNA was concomitantly increased, indicating that these alterations occur at the transcriptional level of protein expression. Transcription of decorin in fibroblasts from one of the patients was stimulated up to 3-fold by treatment with interleukin-1 beta. No response to interleukin-1 beta and transforming growth factor-beta was observed in the cells from another patient. In situ hybridization of cultured cells with an antisense decorin probe showed that decorin levels were reduced throughout the cell population. Surprisingly, subsequent examination of cells from one of the patients, now in mid-teenage, revealed a return to normal levels of decorin expression compared to age-matched controls. These studies suggest that, as in Marfan's syndrome where the primary defect concerns the fibrillin gene, reduced decorin expression contributes to the formation of an abnormal matrix and the pathogenesis of these disorders. They also indicate that this abnormality is likely to represent a secondary phenomenon which leads to a fault in the regulation of decorin gene transcription.
表现出早老样综合征临床特征的年轻患者的成纤维细胞显示，小蛋白聚糖核心蛋白聚糖的生物合成减少。对培养的细胞进行代谢标记，用针对核心蛋白聚糖和双糖链蛋白聚糖的抗体进行免疫沉淀后，对分泌到培养基中的蛋白聚糖进行电泳分析。荧光图谱显示，经软骨素ABC裂解酶处理后，成熟核心蛋白聚糖及其核心蛋白的含量通常降至正常水平的15% - 30%。糖胺聚糖链的大小增加，但成熟蛋白聚糖的分泌动力学没有明显异常。此外，与健康供体的对照细胞相比，患者的成纤维细胞合成的双糖链蛋白聚糖量增加。Northern印迹分析清楚地表明，核心蛋白聚糖mRNA减少了85% - 94%，但双糖链蛋白聚糖mRNA同时增加，表明这些改变发生在蛋白质表达的转录水平。用白细胞介素-1β处理后，一名患者的成纤维细胞中核心蛋白聚糖的转录被刺激了3倍。在另一名患者的细胞中未观察到对白细胞介素-1β和转化生长因子-β的反应。用反义核心蛋白聚糖探针进行培养细胞的原位杂交显示，整个细胞群体中核心蛋白聚糖水平降低。令人惊讶的是，随后对一名现已十几岁的患者的细胞进行检查发现，与年龄匹配的对照相比，核心蛋白聚糖表达恢复到了正常水平。这些研究表明，正如在原纤维蛋白基因存在原发性缺陷的马凡综合征中一样，核心蛋白聚糖表达降低有助于异常基质的形成和这些疾病的发病机制。它们还表明，这种异常可能代表一种继发现象，导致核心蛋白聚糖基因转录调控出现故障。
