Conover C A, Liu F, Powell D, Rosenfeld R G, Hintz R L
Department of Pediatrics, Stanford University, California 94305.
J Clin Invest. 1989 Mar;83(3):852-9. doi: 10.1172/JCI113968.
Specific, high affinity insulin-like growth factor (IGF) binding proteins are secreted by human fibroblasts in culture. By multiple criteria, the species of IGF binding proteins produced by human fibroblasts are distinct from the HepG2/amniotic fluid IGF binding protein, but share many characteristics with the growth hormone-dependent IGF binding protein forms predominant in normal adult human plasma. Treatment of cultured human fibroblasts with growth hormone produced an increase in IGF binding protein activity in the medium, while addition of glucocorticoids markedly diminished IGF binding activity. Insulin, epidermal growth factor, platelet-derived growth factor, and progesterone had no effect on IGF binding activity in fibroblast media. In comparison, HepG2 IGF binding activity was enhanced by progesterone, decreased by insulin, and unaffected by growth hormone or glucocorticoid treatment. Five molecular forms of IGF binding proteins were identified by Western ligand blots in human fibroblast conditioned medium, with Mr = 41,500, 37,000, 32,000, 28,000, and 23,000. In human fibroblast conditioned medium, the Mr = 41,500 and 37,000 IGF binding protein species were abundant, as in normal human plasma, with a major Mr = 23,000 form which was a minor component in plasma.
特异性、高亲和力的胰岛素样生长因子（IGF）结合蛋白由培养的人成纤维细胞分泌。通过多项标准判断，人成纤维细胞产生的IGF结合蛋白种类与HepG2/羊水IGF结合蛋白不同，但与正常成人血浆中占主导的生长激素依赖性IGF结合蛋白形式具有许多共同特征。用生长激素处理培养的人成纤维细胞会使培养基中的IGF结合蛋白活性增加，而添加糖皮质激素则会显著降低IGF结合活性。胰岛素、表皮生长因子、血小板衍生生长因子和孕酮对成纤维细胞培养基中的IGF结合活性没有影响。相比之下，孕酮可增强HepG2的IGF结合活性，胰岛素可降低其活性，生长激素或糖皮质激素处理对其无影响。通过Western配体印迹法在人成纤维细胞条件培养基中鉴定出五种IGF结合蛋白分子形式，其分子量分别为41,500、37,000、32,000、28,000和23,
