Miyakawa Y, Nishimura T, Ueyama Y, Miyake K, Miyasaka M, Ikeda Y, Habu S
Department of Internal Medicine, Keio University, Tokyo, Japan.
Exp Cell Res. 1996 Jul 10;226(1):75-9. doi: 10.1006/excr.1996.0204.
To evaluate the property of binding activity of alpha4beta1 integrin in cell-cell interaction, we newly established a cell line, alpha4mK562, by transfecting cDNA of murine integrin alpha4 subunit into human erythroleukemic K562 cells. alpha4mK562 transfectant expressed both murine alpha4 and human beta1 subunit, which generated a functional heterodimer. alpha4mK562 cells more efficiently bound to murine endothelial cell lines and recombinant human TNFalpha (rhTNF)-treated human umbilical vein endothelial cells (HUVEC) than the parental K562 cells. These adhesion resulted from the interaction between alpha4beta1 and VCAM-1. Interestingly, treatment with mAb against human beta1 (4B4 clone), which has been known as inhibitory mAb, enhanced binding of alpha4mK562 cells to rhTNF-treated HUVEC but not to murine endothelial cells. This increase in binding induced by 4B4 mAb was completely inhibited by another mAb against human beta1 (mAb13), but only partially by anti-alpha4 mAb (PSsolidus2). The increase in binding induced by 4B4 mAb was also abolished by metabolic inhibitors, indicating that the increased binding is energy dependent. These observations suggest that the binding of 4B4 mAb to the chimeric alpha4beta1 induces an unique outside-in signaling and enhances the specific binding of alpha4mK562 cells to rhTNF-treated HUVEC.
为了评估α4β1整合素在细胞间相互作用中的结合活性特性，我们通过将小鼠整合素α4亚基的cDNA转染到人红白血病K562细胞中，新建立了一种细胞系，即α4mK562。α4mK562转染细胞表达小鼠α4和人β1亚基，二者形成功能性异二聚体。与亲代K562细胞相比，α4mK562细胞能更有效地与小鼠内皮细胞系以及重组人肿瘤坏死因子α（rhTNF）处理的人脐静脉内皮细胞（HUVEC）结合。这些黏附是由α4β1与血管细胞黏附分子-1（VCAM-1）之间的相互作用引起的。有趣的是，用已知为抑制性单克隆抗体的抗人β1单克隆抗体（4B4克隆）处理，增强了α4mK562细胞与rhTNF处理的HUVEC的结合，但未增强与小鼠内皮细胞的结合。4B4单克隆抗体诱导的这种结合增加被另一种抗人β1单克隆抗体（mAb13）完全抑制，但仅被抗α4单克隆抗体（PSsolidus2）部分抑制。4B4单克隆抗体诱导的结合增加也被代谢抑制剂消除，这表明增加的结合是能量依赖的。这些观察结果表明，4B4单克隆抗体与嵌合型α4β1的结合诱导了一种独特的由外向内信号传导，并增强了α4mK562细胞与rhTNF处理的HUVEC的特异性结合。
