Functional reconstitution of the human interleukin-3 receptor.
The high-affinity receptors for human interleukin-3 (IL-3), GM-CSF, and IL-5 are composed of alpha and beta subunits. The alpha subunits are primary ligand binding proteins specific for each ligand, whereas the three human receptors share a common beta subunit (beta c). In contrast to humans mice have two closely related genes, AIC2A and AIC2B, which are homologous to human beta c. The AIC2A gene encodes a low-affinity murine IL-3 binding protein, and the AIC2B protein is the beta subunit shared between murine GM-CSF receptors (mGMR) and IL-5 receptors (mIL-5R). To examine the function of these receptor components, we established various stable transfectants of murine IL-2-dependent CTLL-2 cells. CTLL-2 transfectants expressing both the alpha and beta subunits of the human IL-3 receptor (hIL-3R) proliferated in response to physiologic concentrations of hIL-3. Coexpression of hIL-3R alpha with AIC2B but not with AIC2A in CTLL-2 cells conferred a growth response to hIL-3. Although CTLL-2 transfectants expressing hIL-3R alpha alone did not proliferate in the presence of hIL-3, hIL-3-responsive sublines were repeatedly isolated. These sublines expressed endogenous AIC2B but not AIC2A. These results indicate that human beta c is essential for hIL-3 signaling and that AIC2B is a murine equivalent of human beta c. We also showed that hIL-3 and hGM-CSF induced tyrosine phosphorylation of several proteins in CTLL transfectants, similar to those observed in human factor-dependent TF-1 cells stimulated with hIL-3 and hGM-CSF.
Kitamura
T
T
Department of Molecular Biology, DNAX Research Institute of Molecular and Cellular Biology, Palo Alto, CA 94304.
Miyajima
A
A
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007376:Interleukin-2 / Q000494:pharmacology; D007377:Interleukin-3 / Q000378:metabolism / Q000494:pharmacology; D046911:Macromolecular Substances; D051379:Mice; D008970:Molecular Weight; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism; D010766:Phosphorylation; D019000:Phosphotyrosine; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000502:physiology; D016185:Receptors, Interleukin-3 / Q000737:chemistry* / Q000502:physiology; D011994:Recombinant Proteins; D015398:Signal Transduction; D013045:Species Specificity; D013329:Structure-Activity Relationship; D014162:Transfection; D014443:Tyrosine / Q000031:analogs & derivatives / Q000378:metabolism
D007376:Interleukin-2; D007377:Interleukin-3; D046911:Macromolecular Substances; D010750:Phosphoproteins; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D016185:Receptors, Interleukin-3; D011994:Recombinant Proteins; D019000:Phosphotyrosine; D014443:Tyrosine; D016178:Granulocyte-Macrophage Colony-Stimulating Factor