MURINE INTERLEUKIN-7 (IL-7) RECEPTOR - CHARACTERIZATION ON AN IL-7-DEPENDENT CELL-LINE
MURINE INTERLEUKIN-7 (IL-7) RECEPTOR - CHARACTERIZATION ON AN IL-7-DEPENDENT CELL-LINE
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DOI：
10.1084/jem.171.4.1073
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发表时间：
1990-04-01
影响因子：
15.3
通讯作者：
NAMEN, AE
中科院分区：
文献类型：
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作者：
PARK, LS;FRIEND, DJ;NAMEN, AE
已经获得了绝对依赖于外源IL-7持续生长的鼠细胞系（IxN/2b），其表达淋巴样前体和I类MHC抗原，并且还含有重排的μ C抗原。重链该细胞系已用于使用125 I标记的重组鼠IL-7确定鼠IL-7受体的结合和结构特征。125 I-IL-7与IxN/2b细胞的结合是快速的，并且在4 ° C和5 ° C下都是饱和的。和37 ℃。平衡结合研究在两个温度下产生曲线Scatchard图，高和低亲和力Ka值为aptx。1.apprx. 1010 M-1和4 ×108 M-1，并且每个细胞表达总共2，000 - 2，500个IL-7结合位点。测量未标记的IL-7对125 I-IL-7结合的抑制的实验也产生了与两类IL-7受体的存在一致的数据。解离动力学和亲和交联实验提供了关于两类IL-7受体可能的分子性质的证据。当在未标记的IL-7存在下在37 ° C和37 ° C下测量时，125 I-IL-7的解离速率显著增加。和4 ℃，这是显示负协同性的受体群体的诊断。交联研究表明，在还原和非还原条件下，观察到的主要交联物质对应于75-79 kD的受体大小，同时也观察到较低强度的较高分子量交联物质，其对应于约两倍大的受体大小（159-162 kD）。这两种类型的实验表明，IL-7受体可以在膜上形成非共价缔合的二聚体。IL-7受体在前B细胞上表达，但在几种成熟B细胞系或原代成熟B细胞上未检测到。它也表达在小鼠胸腺细胞，一些T细胞系，和骨髓来源的巨噬细胞。所有结合125 I-IL-7的细胞均显示曲线Scatchard图。测试的细胞因子或生长因子均无法抑制125 I-IL-7与其受体的结合。这些结果定义了鼠IL-7受体的初始结合和结构特征以及细胞分布。
A murine cell line (IxN/2b) absolutely dependent upon exogenous IL-7 for continued growth has been obtained that expresses lymphoid precursor and class I MHC antigens and also contains a rearranged .mu. heavy chain. This cell line has been used to define the binding and structural characteristics of the murine IL-7 receptor using 125I-labeled recombinant murine IL-7. 125I-IL-7 binding to IxN/2b cell was rapid and saturable at both 4.degree. and 37.degree.C. Equilibrium binding studies produced curvilinear Scatchard plots at both temperatures with high and low affinity Ka values of .apprx. 1 .apprx. 1010 M-1 and 4 .times. 108 M-1, respectively, and a total of 2,000-2,500 IL-7 binding sites expressed per cell. Experiments measuring inhibition of binding of 125I-IL-7 by unlabeled IL-7 also produced data consistent with the existence of two classes of IL-7 receptors. Evidence concerning the possible molecular nature of two classes of IL-7 receptors was provided by dissociation kinetics and affinity crosslinking experiments. The dissociation rate of 125I-IL-7 was markedly increased when measured in the presence of unlabeled IL-7 at both 37.degree. and 4.degree.C, which is diagnostic of a receptor population displaying negative cooperativity. Crosslinking studies showed that under both reducing and nonreducing conditions, the major crosslinked species observed corresponded to a receptor size of 75-79 kD while a less intense higher molecular mass crosslinked species was also seen which corresponded to a receptor size approximately twice as large (159-162 kD). Both types of experiments suggest that the IL-7 receptor may form noncovalently associated dimers in the membrane. The IL-7 receptor was expressed on pre-B cells, but not detected on several mature B cell lines or primary mature B cells. It was also expressed on murine thymocytes, some T lineage cell lines, and on bone marrow-derived macrophage. All cells binding 125I-IL-7 exhibited curvilinear Scatchard plots. No cytokines or growth factors tested were able to inhibit binding of 125I-IL-7 to its receptor. These results define the initial binding and structural characteristics, and the cellular distribution, of the murine IL-7 receptor.