Reconstitution of functional receptors for human granulocyte/macrophage colony-stimulating factor (GM-CSF): evidence that the protein encoded by the AIC2B cDNA is a subunit of the murine GM-CSF receptor.
The high-affinity receptor for human granulocyte/macrophage colony-stimulating factor (hGM-CSF) is composed of two subunits, alpha and beta. The alpha subunit binds GM-CSF with low affinity, whereas the beta subunit does not bind GM-CSF by itself. The alpha and beta subunits together form the high-affinity GM-CSF receptor. The beta subunit has extensive sequence homology with the mouse interleukin 3 (IL-3) receptor (AIC2A) and its homologue (AIC2B) that does not bind IL-3 or other cytokines including GM-CSF. To examine the function of these receptor components, we expressed the alpha subunit of the hGM-CSF receptor with the human beta subunit or the mouse AIC2A or AIC2B in a mouse IL-3-dependent pro-B-cell line, Ba/F3, and in a mouse IL-2-dependent T-cell line, CTLL2. Coexpression of the alpha and beta subunits in Ba/F3 and CTLL2 cells resulted in high-affinity hGM-CSF binding and growth response to low concentrations of hGM-CSF. Whereas Ba/F3 cells expressing the alpha subunit alone proliferated in response to high concentrations of hGM-CSF, CTLL2 cells expressing the alpha subunit alone did not respond to hGM-CSF at all. Since Ba/F3 cells express endogenous AIC2A and AIC2B whereas CTLL2 expresses neither of them, we examined the possibility that either AIC2A or AIC2B is involved in the formation of a functional GM-CSF receptor. The expression of the human alpha subunit with AIC2B, but not with AIC2A, in CTLL2 cells conferred a growth response to hGM-CSF. These results indicate that the beta subunit of the GM-CSF receptor is required for generation of growth signals and that AIC2B is likely the beta subunit of the mouse GM-CSF receptor.
Kitamura
T
T
Department of Molecular Biology, DNAX Research Institute of Molecular and Cellular Biology, Palo Alto, CA 94304.
Hayashida
K
K
Sakamaki
K
K
Yokota
T
T
Arai
K
K
Miyajima
A
A
D000818:Animals; D001345:Autoradiography; D002460:Cell Line; D003432:Cross-Linking Reagents; D004247:DNA / Q000235:genetics*; D004591:Electrophoresis, Polyacrylamide Gel; D005786:Gene Expression Regulation; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D006801:Humans; D051379:Mice; D010957:Plasmids; D011869:Radioligand Assay; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000235:genetics*; D014162:Transfection
D003432:Cross-Linking Reagents; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D004247:DNA