Ligand-specific utilization of the extracellular membrane-proximal region of the gp130-related signalling receptors.
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.
Hammacher
A
A
Ludwig Institute for Cancer Research, Royal Melbourne Hospital, Victoria 3050, Australia. annet.hammacher@ludwig.edu.au
Wijdenes
J
J
Hilton
D J
DJ
Nicola
N A
NA
Simpson
R J
RJ
Layton
J E
JE
D000818:Animals; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002454:Cell Differentiation; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D050822:Cytokine Receptor gp130; D017931:DNA Primers / Q000235:genetics; D019281:Dimerization; D006801:Humans; D015850:Interleukin-6 / Q000378:metabolism; D008024:Ligands; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D020836:Protein Structure, Quaternary; D016188:Receptors, Granulocyte Colony-Stimulating Factor / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D017931:DNA Primers; C494199:IL6ST protein, human; C494200:Il6st protein, mouse; D015850:Interleukin-6; D008024:Ligands; D008562:Membrane Glycoproteins; D016188:Receptors, Granulocyte Colony-Stimulating Factor; D011993:Recombinant Fusion Proteins; D050822:Cytokine Receptor gp130