Hammacher A, Wijdenes J, Hilton D J, Nicola N A, Simpson R J, Layton J E
Ludwig Institute for Cancer Research, Royal Melbourne Hospital, Victoria 3050, Australia.
Biochem J. 2000 Jan 1;345 Pt 1(Pt 1):25-32.
The receptor gp130 is used by the interleukin-6 (IL-6)-type cytokines, which include IL-6 and leukaemia-inhibitory factor (LIF). To investigate the role of the three extracellular membrane-proximal fibronectin-type-III-like (FNIII) modules of gp130 and the related receptor for granulocyte colony-stimulating factor (G-CSFR) in cytokine signal transduction we have transfected into murine myeloid M1-UR21 cells the chimaera (GR-FNIII)gp130, which contains the membrane-proximal FNIII modules of the G-CSFR on a gp130 backbone, and its complement, the chimaera (gp130-FNIII)GR. Whereas the binding affinities of (125)I-labelled IL-6 to (GR-FNIII)gp130, or of (125)I-Tyr1,3-G-CSF to (gp130-FNIII)GR, were similar to wild-type gp130 and wild-type G-CSFR, respectively, (125)I-LIF failed to bind with high affinity to (GR-FNIII)gp130. In assays measuring differentiation the (gp130-FNIII)GR cells were fully responsive to G-CSF, whereas the (GR-FNIII)gp130 cells responded fully to the agonistic anti-gp130 monoclonal antibody (mAb) B-S12, but not to IL-6 or LIF. Neutralizing mAbs that recognize the membrane-proximal FNIII modules of gp130 or the G-CSFR differentially interfered with signalling by B-S12, LIF and G-CSF. The data suggest that B-S12 and G-CSF induce the correct orientation or conformation for signalling by the wild-type and chimaeric homodimeric receptors, that the membrane-proximal region of gp130 is important for the correct formation of the signalling IL-6-IL-6 receptor-gp130 complex and that this region is also involved in LIF-dependent receptor heterodimerization and signalling.
白细胞介素-6（IL-6）型细胞因子，包括IL-6和白血病抑制因子（LIF），都利用受体gp130。为了研究gp130的三个细胞外膜近端纤连蛋白III型样（FNIII）结构域以及粒细胞集落刺激因子相关受体（G-CSFR）在细胞因子信号转导中的作用，我们将嵌合体（GR-FNIII）gp130转染到小鼠髓样M1-UR21细胞中，该嵌合体在gp130骨架上含有G-CSFR的膜近端FNIII结构域，以及它的互补体嵌合体（gp130-FNIII）GR。虽然（125）I标记的IL-6与（GR-FNIII）gp130的结合亲和力，或（125）I-Tyr1,3-G-CSF与（gp130-FNIII）GR的结合亲和力，分别与野生型gp130和野生型G-CSFR相似，但（125）I-LIF未能与（GR-FNIII）gp130高亲和力结合。在分化测定中，（gp130-FNIII）GR细胞对G-CSF完全有反应，而（GR-FNIII）gp130细胞对激动性抗gp130单克隆抗体（mAb）B-S12完全有反应，但对IL-6或LIF没有反应。识别gp130或G-CSFR膜近端FNIII结构域的中和性单克隆抗体对B-S12、LIF和G-CSF信号传导有不同程度的干扰。数据表明，B-S12和G-CSF诱导野生型和嵌合型同二聚体受体进行信号传导的正确方向或构象，gp130的膜近端区域对于信号传导性IL-6-IL-6受体-gp130复合物的正确形成很重要，并且该区域也参与LIF依赖性受体异二聚化和信号传导。
