Insulin-like growth factor I-dependent regulation of prolidase activity in cultured human skin fibroblasts
Insulin-like growth factor I-dependent regulation of prolidase activity in cultured human skin fibroblasts
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DOI：
10.1023/a:1006958116586
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发表时间：
1998-12-01
影响因子：
4.3
通讯作者：
Palka, J
中科院分区：
文献类型：
--
作者：
Miltyk, W;Kama, E;Palka, J
脯氨酰二肽酶[E.C.3.4.13.9]是一种细胞溶质外肽酶，催化含二肽或三肽的C-末端脯氨酸的水解。该酶在脯氨酸的再循环中起重要作用，用于胶原蛋白合成。酶活性的增加与胶原蛋白周转率的增加相关，但调节这种酶的机制和终点在很大程度上仍然未知。我们已经发现，胰岛素样生长因子-I（IGF-I），胶原生物合成的有效刺激剂，诱导培养的人皮肤成纤维细胞中的脯氨酰二肽酶活性。支持性证据来自以下观察结果：（1）与对照大鼠血清（IGF-I，168 +/- 29）的作用相比，禁食大鼠血清（IGF-I，72 +/- 16 ng/ml）显示刺激融合成纤维细胞中脯氨酰二肽酶活性和胶原生物合成的能力降低约50%。(2)向禁食大鼠血清中加入IGF-I（100 ng/ml）可恢复其刺激脯氨酰二肽酶活性和胶原蛋白生物合成的能力至对照值。(3)在融合的人皮肤成纤维细胞中，用无血清培养基培养48小时，氨脯氨酸二肽酶活性降低至在正常大鼠血清存在下培养的对照细胞的50%。在无血清培养基中添加EGF、PDCF和IGF-I（可替代血清促生长活性的因子）可使脯氨酰二肽酶活性恢复到对照水平，而去除IGF-I的培养基则无此作用。(4)如蛋白质免疫印迹分析所示，由于用上述生长因子特异性处理融合细胞导致的氨酰基脯氨酸二肽酶活性的相对差异伴随着从这些细胞中回收的酶蛋白量的平行差异。因此，我们得出结论，脯氨酰二肽酶活性调节融合成纤维细胞中的IGF-I。
Prolidase [E.C.3.4.13.9] is a cytosolic exopeptidase that catalyses the hydrolysis of C-terminal proline containing dipeptides or tripeptides. The enzyme plays an important role in the recycling of proline for collagen synthesis. Increase in enzyme activity is correlated with increased rates of collagen turnover but the mechanism and endpoints by which this enzyme is regulated remain largely unknown. We have found that insulin-like growth factor-I (IGF-I), potent stimulator of collagen biosynthesis, induces prolidase activity in cultured human skin fibroblasts. Supporting evidence comes from the following observations: (1) Serum of fasted rats, (IGF-I, 72 +/- 16 ng/ml) showed about 50% reduced ability to stimulate prolidase activity and collagen biosynthesis in confluent fibroblasts in comparison to the effect of control rat serum (IGF-I, 168 +/- 29). (2) An addition of IGF-I (100 ng/ml) to fasted rat serum restored its ability to stimulate prolidase activity and collagen biosynthesis to control values. (3) In confluent human skin fibroblasts, cultured for 48 h with serum free medium prolidase activity was decreased to 50% of control cells, cultured in the presence of normal rat serum. Supplementation of serum free medium with EGF, PDCF and IGF-I (factors that can replace growth promoting activity of serum) stimulated prolidase activity to control values while the medium deprived IGF-I had no such effect. (4) The relative differences in prolidase activity due to specific treatment of confluent cells with above growth factors were accompanied by parallel differences in the amount of the enzyme protein recovered from these cells as shown by western immunoblot analysis. Thus we conclude that prolidase activity is regulated by IGF-I in confluent fibroblasts.