Purified human somatomedin A and rat multiplication stimulating activity. Mitogens for cultured fibroblasts that cross-react with the same growth peptide receptors.
Purified human somatomedin A and rat multiplication stimulating activity. Mitogens for cultured fibroblasts that cross-react with the same growth peptide receptors.
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纯化的人生长调节素 A 和大鼠增殖刺激活性。
DOI：
10.1111/j.1432-1033.1978.tb11991.x
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发表时间：
1978
期刊：
影响因子：
--
通讯作者：
Alan C. Moses
中科院分区：
文献类型：
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作者：
M. Rechler;Linda Fryklund;S. Nissley;Kerstin Hall;J. Podskalny;Anna Skottner;Alan C. Moses
我们比较了生长调节素 A 和增殖刺激活性 (MSA) 的受体结合测定中的促有丝分裂活性和反应性，这两种分子量为 7-10 000 的酸溶性多肽，具有较弱的内在胰岛素样代谢活性。生长调节素 A 从人血浆中纯化至同质，MSA 从源自大鼠肝脏的细胞系 BRL 3A 的条件培养基中纯化至同质。这两种肽可将鸡胚成纤维细胞中的 DNA 合成刺激 3-4 倍，并具有重叠的剂量反应曲线。向铺在无血清培养基中的鸡胚成纤维细胞中添加任一肽后，细胞数量在 4 天内增加了 150%，而未添加任何肽的对照培养物中细胞数量增加了 25%。这两种肽还刺激培养物中人成纤维细胞的 DNA 合成 3-4 倍。
MSA 和/或生长调节素 A 的特异性受体可以在鸡胚成纤维细胞、人成纤维细胞、人胎盘、大鼠肝脏和 BRL 3A2 细胞系（产生 MSA 细胞系的亚克隆）的完整细胞或细胞膜中得到证实。未标记的 MSA 和生长调节素 A 以相当的效力抑制 125 I 标记的 MSA 和 125 I 标记的生长调节素 A 与这些受体中每一种的结合。在鸡胚成纤维细胞、人成纤维细胞和人胎盘膜中，两种放射性配体的结合也受到胰岛素的抑制，这与 125I 标记的 MSA 和 125I 标记的生长调节素 A 与同一受体结合的解释一致。相比之下，在 BRL 3A2 细胞系中，胰岛素抑制 125I 标记的生长调节素 A 的结合，但不抑制 125I 标记的 MSA 的结合，表明两种标记的肽与该细胞系中的不同受体结合。此外，125I 标记的 MSA（而非 125I 标记的生长调节素 A）特异性结合至大鼠肝脏质膜。这些结果表明，人生长调节素 A 和大鼠 MSA 是密切相关但不相同的肽。它们对培养的成纤维细胞具有相似的有丝分裂活性，并与具有相当效力的特定细胞受体发生交叉反应。然而，这两种放射性标记的肽可以通过生长调节素样肽的某些细胞表面受体来区分。
We have compared the mitogenic activity and reactivity in receptor binding assays of somatomedin A and multiplication-stimulating activity (MSA), two acid-soluble polypeptides of molecular weight 7–10 000 that possess weak intrinsic insulin-like metabolic activity. Somatomedin A was purified to homogeneity from human plasma, and MSA was purified to homogeneity from the conditioned culture media of a cell line, BRL 3A, derived from rat liver. The two peptides stimulated DNA synthesis in chick embryo fibroblasts 3–4-fold and have superimposable dose-response curves. Addition of either peptide to chick embryo fibroblasts plated in serum-free medium increased the cell number by 150% in 4 days, compared with an increase of 25% in control cultures receiving no additions. The two peptides also stimulated DNA synthesis in human fibroblasts in culture 3–4-fold.
Specific receptors for MSA and/or somatomedin A could be demonstrated in intact cells or membranes from chick embryo fibroblasts, human fibroblasts, human placenta, rat liver, and the BRL 3A2 cell line, a subclone of the line that produces MSA. Unlabeled MSA and somatomedin A inhibited the binding of 125I-labeled MSA and 125I-labeled somatomedin A to each of these receptors with comparable potency. In chick embryo fibroblasts, human fibroblasts, and human placental membranes, the binding of both radioactive ligands also was inhibited by insulin, consistent with the interpretation that 125I-labeled MSA and 125I-labeled somatomedin A were binding to the same receptor. By contrast, in the BRL 3A2 cell line, insulin inhibited the binding of 125I-labeled somatomedin A, but not the binding of 125I-labeled MSA, suggesting that the two labeled peptides were binding to different receptors in this cell line. Moreover, 125I-labeled MSA, but not 125I-labeled somatomedin A, bound specifically to rat liver plasma membranes. These results indicate that human somatomedin A and rat MSA are closely related, but not identical, peptides. They have similar mitogenic activity for cultured fibroblasts, and cross-react with specific cell receptors with comparable potency. The two radioactively labeled peptides, however, can be distinguished by certain cell surface receptors for somatomedin-like peptides.