Barile F A, Siddiqi Z E, Ripley-Rouzier C, Bienkowski R S
Department of Natural Sciences, York College of the City University of New York, Jamaica 11451.
Arch Biochem Biophys. 1989 Apr;270(1):294-301. doi: 10.1016/0003-9861(89)90031-3.
Amino acid substitutions in collagen that impair folding of the triple helix result in significant increases in intracellular degradation of newly synthesized collagen. We have studied the effects of agents that cause other kinds of defects in collagen: hydroxynorvaline, a threonine analog that interferes with association of pro-alpha chains; and puromycin, an antibiotic that causes premature release of nascent polypeptides. cis-Hydroxyproline and cycloheximide, whose effects on collagen synthesis and degradation have already been studied and reported, were employed as reference compounds. Human fetal lung fibroblasts were used in these experiments. All the agents inhibited total protein production, and all except cycloheximide inhibited percentage collagen production. Intracellular collagen degradation was increased in cultures exposed to puromycin, hydroxynorvaline, and cis-hydroxyproline, but not in cultures exposed to cycloheximide. These results suggest that pro-alpha chains that were either unassociated (due to hydroxynorvaline) or shortened (due to puromycin) were recognized as abnormal and degraded to the same extent as chains that contained cis-hydroxyproline. However, the increases in degradation could not account completely for the decreases in collagen production (except when cis-hydroxyproline was used at low concentrations). These findings indicate that, in addition to rendering newly synthesized procollagen molecules or partial polypeptide chains more susceptible to intracellular degradation, puromycin, hydroxynorvaline, and cis-hydroxyproline significantly inhibited collagen synthesis.
胶原蛋白中影响三螺旋折叠的氨基酸替换会导致新合成胶原蛋白的细胞内降解显著增加。我们研究了导致胶原蛋白出现其他类型缺陷的试剂的作用：羟正缬氨酸，一种干扰前α链缔合的苏氨酸类似物；以及嘌呤霉素，一种导致新生多肽提前释放的抗生素。顺式羟脯氨酸和环己酰亚胺，其对胶原蛋白合成和降解的作用已被研究并报道，用作参考化合物。这些实验使用了人胎儿肺成纤维细胞。所有试剂均抑制总蛋白产生，除环己酰亚胺外，所有试剂均抑制胶原蛋白产生百分比。暴露于嘌呤霉素、羟正缬氨酸和顺式羟脯氨酸的培养物中细胞内胶原蛋白降解增加，但暴露于环己酰亚胺的培养物中未增加。这些结果表明，未缔合（由于羟正缬氨酸）或缩短（由于嘌呤霉素）的前α链被识别为异常，并与含有顺式羟脯氨酸的链以相同程度降解。然而，降解的增加并不能完全解释胶原蛋白产生的减少（低浓度使用顺式羟脯氨酸时除外）。这些发现表明，除了使新合成的前胶原分子或部分多肽链更易受细胞内降解外，嘌呤霉素、羟正缬氨酸和顺式羟脯氨酸还显著抑制胶原蛋白合成。
