GM-CSF binding to its receptor induces oligomerisation of the common beta-subunit.
The stoichiometry of the granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor complex is still unresolved. We have utilised a sensitive, functional assay for receptor homodimerisation to show that GM-CSF induces dimerisation of the common signalling subunit, hbeta(c). We generated a chimeric cytokine receptor in which the extracellular and transmembrane domains of hbeta(c)are fused to the cytoplasmic domain of erythropoietin receptor (EPO-R). Given that to induce EPO-R activation and mitogenic signalling there is a requirement for formation of a specific homodimeric complex, we reasoned that the cytoplasmic domain of EPO-R could be utilised as a highly sensitive reporter for functional homodimer formation. We show that, in the presence of a cytoplasmically truncated GM-CSF alpha-subunit, the hbetac-EPO receptor chimera transduces a mitogenic signal in BaF-B03 in response to GM-CSF. This is consistent with formation of a hbeta(c)homodimer following GM-CSF binding and implies that ligand stimulation induces formation of a higher order complex that contains the hbeta(c)homodimer.
Division of Human Immunology, Hanson Centre for Cancer Research, Frome Road, Adelaide, South Australia, 5000, Australia.
B J
BJ
McClure
J M
JM
Woodcock
D
D
Harrison-Findik
A F
AF
Lopez
R J
RJ
D'Andrea
D000818:Animals; D002460:Cell Line; D053648:Cytokine Receptor Common beta Subunit; D019281:Dimerization; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D051379:Mice; D011485:Protein Binding / Q000502:physiology; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism* / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology
C115876:CSF2RB protein, human; D053648:Cytokine Receptor Common beta Subunit; D011956:Receptors, Cell Surface; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D011993:Recombinant Fusion Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor