Insulin-like growth factor (IGF) binding to human fibroblast and glioblastoma cells: the modulating effect of cell released IGF binding proteins (IGFBPs).
Insulin-like growth factor (IGF) binding to human fibroblast and glioblastoma cells: the modulating effect of cell released IGF binding proteins (IGFBPs).
复制标题
胰岛素样生长因子 (IGF) 与人成纤维细胞和胶质母细胞瘤细胞结合：细胞释放的 IGF 结合蛋白 (IGFBP) 的调节作用。
DOI：
10.1002/jcp.1041440210
复制
发表时间：
1990
影响因子：
5.6
通讯作者：
Clemmons,DR
中科院分区：
文献类型：
--
作者：
McCusker,RH;Camacho-Hubner,C;Bayne,ML;Cascieri,MA;Clemmons,DR
人成纤维细胞的细胞表面不仅含有II型IGF受体，而且含有至少两种形式的IGFBPs。进行研究以分析这些IGFBPs改变IGF-I-细胞表面相互作用的机制。选择人胎儿成纤维细胞（GM 10）和人胶质母细胞瘤细胞系（1690）进行分析。在定量[125 I]-IGF-1结合的测定期间，两种细胞系均显示将IGFBP释放到结合测定缓冲液中。在平衡条件下，[125 I]-IGF-I优先与测定缓冲液中的IGFBPs结合（最多40%的[125 I]-IGF-I加入），因为它们具有比与细胞表面结合的II型IGF受体或IGFBPs更高的亲和力。同样，添加浓度增加的未标记IGF-I导致优先竞争与测定缓冲液IGFBPs结合。这导致与测定缓冲液IGFBP结合的[125 I]-IGF-I重新分配到细胞表面结合位点上。再分配的程度与[125 I]-IGF-I结合释放IGFBP的量定量相关。当在结合测定之前将培养物暴露于放线菌酮时，释放到测定缓冲液中的IGFBP的量和再分配的[125 I]-IGF-1的量均降低。相反，当[Gln 3，Ala 4，Tyr 15，Leu 16]-IGF-1（IQAYL j-IGF-I，一种对I型IGF受体具有不变亲和力的IGF类似物）被碘化并测试时，未标记的IGF-I的竞争曲线显示无再分配效应。这种形式的IGF可用于定量I型受体数量，而不依赖于IGFBP的存在。IGF-I和[QAYL]-IGF-I与[125 I]-[QAYL]-IGF-I同等地竞争结合细胞表面，而未标记的[QAYL]-IGF-I与[125 I]-IGF-I竞争细胞表面结合的效力比IGF-I低> 25倍。[125 I]-[QAYL]-IGF-I与GM 10和1690细胞表面的特异性结合<[125 I]-IGF-I结合的20%。这些发现表明，IGFBPs是目前在人成纤维细胞表面代表了大部分的IGF结合位点。我们得出结论，释放到测定缓冲液中的IGFBPs的量是[125 I]-IGF-I重新分配到细胞表面结合位点的主要决定因素，并且细胞表面和测定缓冲液IGFBPs均调节I型IGF受体结合。
The cell surface of human fibroblasts contains not only type IIGF receptors but at least two forms of IGFBPs. Studies were undertaken to analyze the mechanisms by which these IGFBPs alter IGF‐I‐cell surface interactions. Human fetal fibroblasts (GM10) and a human glioblastoma cell line (1690) were chosen for analysis. During assays to quantify [125l]‐IGF‐l binding, both cell lines were shown to release IGFBPs into the binding assay buffer. Under equilibrium conditions, [125I]‐IGF‐I preferentially associates with IGFBPs in the assay buffer (up to 40% of the [125I]‐IGF‐I added) since they have a higher affinity than type IIGF receptors or IGFBPs associated with the cell surface. Likewise the addition of increasing concentrations of unlabeled IGF‐I results in preferential competition for binding to assay buffer IGFBPs. This results in a repartitioning of the [125I]‐IGF‐I that is bound to assay buffer IGFBPs onto cell surface binding sites. The degree of repartitioning is quantitatively related to the amount of [125I]‐IGF‐I bound to released IGFBPs. When cultures are exposed to cycloheximide before the binding assay, both the amount of IGFBPs that are released into the assay buffer and the amount of [125I]‐IGF‐l that is repartitioned are decreased. In contrast when [Gln3, Ala4, Tyr15, Leu16]‐IGF‐l (IQAYLj‐IGF‐I, an IGF analog that has unaltered affinity for type I IGF receptors) is iodinated and tested, the competition curve with unlabeled IGF‐I shows no repartitioning effect. This form of IGF can be used to quantify type I receptor number independent of the presence of IGFBPs. IGF‐I and the [QAYL]‐IGF‐I compete equally with the [125I]‐[QAYL]‐IGF‐I for binding to cell surfaces, whereas unlabeled [QAYL]‐IGF‐I is > 25‐fold less potent compared to IGF‐I in competing with [125I]‐IGF‐I for cell surface binding. Specific binding of [125I]‐[QAYL]‐IGF‐I to GM10 and 1690 cell surfaces is < 20% of [125I]‐IGF‐I binding. These findings suggest that IGFBPs that are present on human fibroblast surfaces represent a large portion of the IGF binding sites. We conclude that the amount of IGFBPs released into assay buffer is a major determinant of the repartitioning of [125I]‐IGF‐I to cell surface binding sites and that both cell surface and assay buffer IGFBPs modulate type I IGF receptor binding.
登录
查看更多内容
DOI：
--
发表时间：
1993-12
期刊：
The Journal of rheumatology
影响因子：
--
作者：
P. Clements;P. Lachenbruch;J. Seibold;B. Zee;V. Steen;P. Brennan;A. Silman;N. Allegar;J. Varga;M. Massa
通讯作者：
P. Clements;P. Lachenbruch;J. Seibold;B. Zee;V. Steen;P. Brennan;A. Silman;N. Allegar;J. Varga;M. Massa
影响因子：
6
作者：
Pilewski, JM;Liu, LX;Feghali-Bostwick, CA
通讯作者：
Feghali-Bostwick, CA
影响因子：
20.3
作者：
John I. Jones;D. Clemmons
通讯作者：
John I. Jones;D. Clemmons
影响因子：
2.3
作者：
Denko CW;Malemud CJ
通讯作者：
Malemud CJ
影响因子：
20.3
作者：
Zhang, CC;Lodish, HF
通讯作者：
Lodish, HF