Reconstitution of the functional receptors for murine and human interleukin 5.
The murine interleukin 5 receptor (mIL-5R) is composed of two distinct subunits, alpha and beta. The alpha subunit (mIL-5R alpha) specifically binds IL-5 with low affinity. The beta subunit (mIL-5R beta) does not bind IL-5 by itself, but forms the high-affinity receptor with mIL-5R alpha. mIL-5R beta has been revealed to be the mIL-3R-like protein, AIC2B which is shared with receptors for IL-3 and granulocyte/macrophage colony-stimulating factor. We demonstrated here the reconstitution of the functional receptors for murine and human IL-5 on the mouse IL-2-dependent cell line, CTLL-2. CTLL-2 was transfected with the cDNAs for mIL-5R alpha and/or AIC2B. Only CTLL-2 transfectant expressing both mIL-5R alpha and AIC2B expressed the high-affinity receptor and proliferated in response to murine IL-5. Then CTLL-2 was transfected with the cDNAs for hIL-5R alpha and/or KH97 (beta c), the human homologue of AIC2B. Though beta c did not contribute much to binding affinity of hIL-5R, only CTLL-2 transfectant expressing both hIL-5R alpha and beta c proliferated in response to human IL-5. These results showed that the beta subunit is indispensable in IL-5 signal transduction. We further investigated the function of IL-5-specific alpha subunit in transmitting IL-5 signals. Mutant mIL-5R alpha, which lacks its whole cytoplasmic domain, was transfected into mouse IL-3-dependent cell line, FDC-P1 expressing AIC2B intrinsically. The resulting transfectant did not respond to IL-5, though the transfectant expressed the high-affinity IL-5R, indicating that the cytoplasmic portion of the alpha subunit also has some important role in IL-5-mediated signal transduction.
Takaki
S
S
Department of Immunology, University of Tokyo, Japan.
Murata
Y
Y
Kitamura
T
T
Miyajima
A
A
Tominaga
A
A
Takatsu
K
K
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D015848:Interleukin-5 / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D011971:Receptors, Immunologic / Q000032:analysis* / Q000737:chemistry / Q000502:physiology; D018123:Receptors, Interleukin; D053649:Receptors, Interleukin-5; D015398:Signal Transduction; D014162:Transfection
D007376:Interleukin-2; D015848:Interleukin-5; D011971:Receptors, Immunologic; D018123:Receptors, Interleukin; D053649:Receptors, Interleukin-5