Activation of the STAT3/Acute Phase Response Factor Transcription Factor by Interleukin-5 (1995)

The receptor for interleukin-5 (IL-5R) is composed of a unique α chain (IL-5Rα) expressed on eosinophils and basophils, associated with a βc subunit, which is shared by the receptors for IL-3 and granulocyte macrophage-colony stimulating factor. One of the molecular events activated via the IL-5R is the JAK/STAT signaling pathway. Recent reports have shown that IL-5 induces tyrosine phosphorylation of JAK2 followed by the subsequent cell type-specific activation of either STAT1α or STAT5. To identify additional STAT proteins activated by IL-5, we co-transfected the IL-5R with STAT cDNAs in COS cells. We found that IL-5 induces binding of STAT3 to the intercellular adhesion molecule-1 pIRE, and activates STAT3-dependent transcription. Moreover, endogenous STAT3 was tyrosine phosphorylated and activated in human IL-5-stimulated BaF3 cells ectopically expressing the human IL-5R (BaF3/IL5R). These data imply that multiple STAT proteins are involved in gene regulation by IL-5 in a cell type-specific manner. We further demonstrate using C-terminal truncations of the α and βc subunits of the IL-5R that the membrane-proximal regions of both subunits are required for STAT activation. Interestingly, a βc receptor mutant lacking intracellular tyrosine residues is able to mediate STAT3 activation, suggesting that tyrosine phosphorylation of the βc receptor is not essential for STAT3 activation. The receptor for interleukin-5 (IL-5R) is composed of a unique α chain (IL-5Rα) expressed on eosinophils and basophils, associated with a βc subunit, which is shared by the receptors for IL-3 and granulocyte macrophage-colony stimulating factor. One of the molecular events activated via the IL-5R is the JAK/STAT signaling pathway. Recent reports have shown that IL-5 induces tyrosine phosphorylation of JAK2 followed by the subsequent cell type-specific activation of either STAT1α or STAT5. To identify additional STAT proteins activated by IL-5, we co-transfected the IL-5R with STAT cDNAs in COS cells. We found that IL-5 induces binding of STAT3 to the intercellular adhesion molecule-1 pIRE, and activates STAT3-dependent transcription. Moreover, endogenous STAT3 was tyrosine phosphorylated and activated in human IL-5-stimulated BaF3 cells ectopically expressing the human IL-5R (BaF3/IL5R). These data imply that multiple STAT proteins are involved in gene regulation by IL-5 in a cell type-specific manner. We further demonstrate using C-terminal truncations of the α and βc subunits of the IL-5R that the membrane-proximal regions of both subunits are required for STAT activation. Interestingly, a βc receptor mutant lacking intracellular tyrosine residues is able to mediate STAT3 activation, suggesting that tyrosine phosphorylation of the βc receptor is not essential for STAT3 activation. INTRODUCTIONHematopoiesis is tightly regulated by a complex network of stromal interactions and by soluble polypeptide factors named cytokines. IL-3, 1The abbreviations used are: ILinterleukinGM-CSFgranulocyte macrophage-colony stimulating factorIL-5Rreceptor for IL-5JAKjanus kinaseSTATsignal transducer and activator of transcriptionSH domainSrc homology domainIFNinterferonhILhuman interleukinGRRγ responsive regionICAM-1intercellular adhesion molecule-1pIREpalindromic IL-6/IFN-γ response elementSIESis-inducible element. IL-5, and GM-CSF are cytokines that have diverse effects on the proliferation, differentiation, and activation of blood cells and their precursors (1Arai K.I. Lee F. Miyajima A. Miyatake S. Arai N. Yokota T. Annu. Rev. Biochem. 1990; 59: 783-836Crossref PubMed Scopus (1168) Google Scholar, 2Lopez A.F. Elliott M.J. Woodcock J. Vadas M.A. Immunol. Today. 1992; 13: 495-500Abstract Full Text PDF PubMed Scopus (127) Google Scholar, 3Ogawa M. Blood. 1993; 81: 2844-2853Crossref PubMed Google Scholar). Whereas IL-3 and GM-CSF also have effects on other hematopoietic lineages(3Ogawa M. Blood. 1993; 81: 2844-2853Crossref PubMed Google Scholar, 4Clutterbuck E.J. Hirst E.M. Sanderson C.J. Blood. 1989; 73: 1504-1512Crossref PubMed Google Scholar), the effect of IL-5 in humans is restricted to eosinophils and basophils. IL-5 is essential for eosinophil differentiation (5Campbell H.D. Tucker W.Q.J. Hort Y. Martinson M.E. Mayo G. Clutterbuck E.J. Sanderson C.J. Young I.G. Proc. Natl. Acad. Sci. U. S. A. 1987; 84: 6629-6633Crossref PubMed Scopus (266) Google Scholar, 6Sanderson C.J. Warren D.J. Strath M. J. Exp. Med. 1985; 162: 60-74Crossref PubMed Scopus (225) Google Scholar) and plays an important role in the function of mature eosinophils(7Silberstein D.S. Owen W.F. Gasson J.C. DiPersio J.F. Golde D.W. Bina J.C. Soberman R. Austen K.F. David J.R. J. Immunol. 1986; 137: 3290-3294PubMed Google Scholar, 8Lopez A.F. Sanderson C.J. Gamble J.R. Campbell H.D. Young I.G. Vadas M.A. J. Exp. Med. 1988; 167: 219-224Crossref PubMed Scopus (801) Google Scholar, 9Fujisawa T. Abu Ghazaleh R. Kita H. Sanderson C.J. Gleich G.J. J. Immunol. 1990; 144: 642-646PubMed Google Scholar, 10van der Bruggen T. Kok P.T.M. Raaijmakers J.A.M. Verhoeven A.J. Kessels R.G.C. Lammers J.W.J. Koenderman L. J. Leukocyte Biol. 1993; 53: 347-353Crossref PubMed Scopus (49) Google Scholar, 11van der Bruggen T. Kok P.T.M. Raaijmakers J.A.M. Lammers J.W.J. Koenderman L. J. Immunol. 1994; 153: 2729-2735PubMed Google Scholar). The specific effects of IL-5 on eosinophils and basophils are due to restricted expression of the low affinity IL-5Rα receptor on these cell types(12Chihara J. Plumas J. Gruart V. Tavernier J. Prin L. Capron A. Capron M. J. Exp. Med. 1990; 172: 1347-1351Crossref PubMed Scopus (93) Google Scholar, 13Ingley E. Young I.G. Blood. 1991; 78: 339-344Crossref PubMed Google Scholar). The high affinity receptor for IL-5 (IL-5R) is composed of a unique α subunit associated with a βc subunit that is shared with the receptors for IL-3 and GM-CSF(14Tavernier J. Devos R. Cornelis S. Tuypens T. Van der Heyden J. Fiers W. Plaetinck G. Cell. 1991; 66: 1175-1184Abstract Full Text PDF PubMed Scopus (493) Google Scholar). The βc subunit is essential for signal transduction(15Kitamura T. Miyajima A. Blood. 1992; 80: 84-90Crossref PubMed Google Scholar, 16Miyajima A. Mui A.L. Ogorochi T. Sakamaki Blood. 1993; PubMed Google Scholar), the α chain intracellular S. H. M. Cell. Biol. 1994; PubMed Google Scholar). the of the βc subunit by IL-3, IL-5, and GM-CSF the of these A. Mui A.L. Ogorochi T. Sakamaki Blood. 1993; PubMed Google Scholar, A. T. T. Biochem. Sci. 1992; Full Text PDF PubMed Scopus Google Scholar). signal are not and are to composed of both and differentiation is that the βc subunit, other not tyrosine N. Sakamaki N. Arai Miyajima A. J. 1993; PubMed Scopus Google Scholar, A.L. Miyajima A. Proc. Exp. Biol. Med. 1994; PubMed Scopus Google Scholar). of the events to IL-3, IL-5, and GM-CSF is of tyrosine N. Sakamaki N. Arai Miyajima A. J. 1993; PubMed Scopus Google Scholar, Miyajima T. Miyajima A. J. 1992; PubMed Scopus Google Scholar). tyrosine phosphorylation is by the activation of tyrosine T. R. J.C. Blood. 1992; 80: PubMed Google Scholar, L. R. J. Exp. Med. PubMed Scopus Google Scholar) and Y. S. H. Miyajima A. Arai Y. H. J. 1993; PubMed Scopus Google Scholar). Recent have that the of and is associated with receptors and is phosphorylated Full Text PDF PubMed Scopus Google Scholar). We and have shown that JAK2 is activated in response to IL-3, IL-5, and GM-CSF T. Proc. Natl. Acad. Sci. U. S. A. 1993; PubMed Scopus Google Scholar, der Bruggen T. E. Raaijmakers J.A.M. Lammers J.W.J. Koenderman L. Blood. PubMed Google Scholar, S. T. S. Y. Y. S. S. T. J. Exp. Med. 1994; PubMed Scopus Google Scholar) and with the membrane-proximal of the N. M. Miyajima A. Cell. Biol. 1994; PubMed Google Scholar). The of a of factors named signal and of Full Text PDF PubMed Scopus Google proteins in the signaling D.S. Proc. Natl. Acad. Sci. U. S. A. 1990; PubMed Scopus Google Scholar, T. R. Proc. Natl. Acad. Sci. U. S. A. 1992; PubMed Scopus Google Scholar). have and are involved in specific T. R. Proc. Natl. Acad. Sci. U. S. A. 1992; PubMed Scopus Google Scholar, 1994; PubMed Scopus Google Scholar, D.J. Cell. Biol. 1994; PubMed Scopus Google Scholar, J. Exp. Med. PubMed Scopus Google Scholar, F. H. M. J. 1994; 13: PubMed Scopus Google Scholar, A.L. H. N. Miyajima A. J. PubMed Scopus Google Scholar, F. H. G. J. PubMed Scopus Google Scholar, J. U. M. 1994; PubMed Scopus Google Scholar, W. A. Cell. Biol. PubMed Scopus Google Scholar). of STAT proteins a of factors that homology and a tyrosine phosphorylation Full Text PDF PubMed Scopus Google Scholar). STAT proteins in the phosphorylation on or which to the and to specific Cell. 1993; Full Text PDF PubMed Scopus Google Scholar, David M. D.S. D.S. 1993; PubMed Scopus Google Scholar, J. F. Cell. Biol. 1993; 13: PubMed Scopus Google Scholar, E. J. A. F. W. der J. Biol. 1994; Full Text PDF PubMed Google Scholar, A. M. F. W. Google Scholar). We found that STAT3 is also phosphorylated on J. E. W. H. PubMed Scopus (93) Google Scholar). phosphorylation to for the regulation of the of have shown that IL-5 activates STAT1α with an in human der Bruggen T. E. Raaijmakers J.A.M. Lammers J.W.J. Koenderman L. Blood. PubMed Google Scholar). we other STAT proteins activated by we both subunits of the IL-5 receptor with STAT cDNAs in COS cells. We that STAT3 was also activated by IL-5 in these COS cells. endogenous STAT3 was tyrosine phosphorylated and activated by in BaF3 cells expressing the (BaF3/IL5R). we using truncations of both the α and that the membrane-proximal of both subunits are for STAT3 and cells in with cell and BaF3 cells expressing the human IL-5 receptor α and subunits in with and the BaF3 cells in with IL-3 cells in with of and was The was The STAT3 was and with the used in the are the human pIRE, a mutant pIRE, the and the The by E. J. A. F. W. der J. Biol. 1994; Full Text PDF PubMed Google also the expression S. der W. 1993; PubMed Scopus Google Scholar). The and by either the or in the of the in was by the for human STAT1α 1993; PubMed Scopus Google Scholar) the of S. E. 1988; PubMed Scopus Google Scholar). was by the human STAT3 a human eosinophil was by the for 1994; PubMed Scopus Google Scholar) the of was by the for H. F. J. 1994; 13: PubMed Scopus Google Scholar) the of was by the for human J. U. M. 1994; PubMed Scopus Google Scholar) the of was by the for the human receptor 1994; Google Scholar) the of was by the for the human βc subunit J. Devos R. Cornelis S. Tuypens T. Van der Heyden J. Fiers W. Plaetinck G. Cell. 1991; 66: 1175-1184Abstract Full Text PDF PubMed Scopus (493) Google Scholar) the of of the of the IL-5 receptor α and the using of of the human IL-5Rα and βc the gene the BaF3 cells by using Miyajima T. Miyajima A. J. 1992; PubMed Scopus Google Scholar), and using of the α and βc subunits was by and by in the of COS cells in and the cells with of by the der A.J. Cell. Biol. Scholar). of to the was and cells for with cells for J.F. 1989; Google Scholar) and R. W. F. J.F. J. 1990; Google and COS and BaF3 cells a M. PubMed Scopus Google Scholar). by in the with using of to with D.S. Proc. Natl. Acad. Sci. U. S. A. 1990; PubMed Scopus Google Scholar). in a of of of and of for for with the of to the of of the binding proteins was by for on with of the and and IL-5 BaF3 cells with for on The was to and The cell with the for with for with and in The proteins on a and to in with the was either with the or with the the with and STAT3 the was with for with the was for with or both the was with and proteins with of the IL-5 in COS in STAT3 by have shown that IL-5 of human eosinophils activates the binding of multiple to the the der Bruggen T. E. Raaijmakers J.A.M. Lammers J.W.J. Koenderman L. Blood. PubMed Google Scholar). We also that of these STAT1α by using STAT1α specific the of the other proteins activated by IL-5 One to IL-5 also other of the STAT is to STAT activation by IL-5 in COS cells. We these cells with expression the human IL-5Rα and subunits in with expression the STAT These co-transfected with a to the and the gene We the to and E. J. A. F. W. der J. Biol. 1994; Full Text PDF PubMed Google Scholar). We STAT activation by IL-5 the of in COS cells with the expression STAT cDNAs an in which is due to endogenous in COS cells. of in an of with cells with IL-5 also activated which in a of a for we COS cells with the for STAT3 and the cells with We that STAT3 was not activated by was able to and R. we effect of IL-5 on of the cDNAs for and These that IL-5 the of both STAT1α and STAT3 in COS is a for we and IL-5-stimulated COS cells with COS cells with IL-5 for a binding complex is using the a is a specific binding complex with an of pIRE, a was to for To that was we with shown in STAT3 to the complex and is not able to the a with STAT1α effect on These that IL-5 activates STAT3 binding to the induces a binding complex The receptor and STAT3 expressed in COS cells. These cells either or for with IL-5, which for binding to the in for with a of of the STAT the with either or for the of the IL-5 induces binding of STAT3 to the further the of the STAT3 These with COS cells with the IL-5R and STAT3 and with IL-5 for The was used a and we used the the Cell. 1993; Full Text PDF PubMed Scopus Google Scholar) and the David M. D.S. D.S. 1993; PubMed Scopus Google Scholar). that with a of either the or binding of STAT3 to the pIRE, a mutant was to for with the in a of STAT3 binding to the pIRE, suggesting that the is a binding for STAT3 the We also the of STAT3 on the We of the in of a was in COS cells with cDNAs the IL-5Rα and βc subunits and shown in of the IL-5R and STAT3 in the of IL-5 in a of via the The in is with the of a these that IL-5 is of STAT3 in COS STAT3 is not restricted to the COS cells expressing the receptor and STAT3 with IL-5 for and with a for with a of STAT3 to other STAT binding COS cells with the and STAT3 cDNAs with either a or a cells with IL-5 and with and was to cells. the of IL-5 induces activation of both and by and of STAT3 in the using cells we the of endogenous STAT3 activated by we used the which we with the human IL-5Rα and βc subunits (BaF3/IL5R). tyrosine phosphorylation of STAT proteins is we STAT3 and cells. phosphorylation of STAT3 was by using the shown in with in phosphorylation of the STAT3 and activation of STAT3 by in cells. BaF3 cells expressing the receptor or with for endogenous STAT3 was these cells with a specific by with the The was and with the STAT3 specific induces of STAT3 on tyrosine these cells in a using the a The cells with either or The binding complex both STAT1α and to tyrosine and to the to specific and cells with a and in a that with for in the of binding The in BaF3 To the of the binding proteins by we with STAT1α and We found that complex and the of complex and The complex was not by either STAT1α or STAT3 We these data that in activates both STAT1α and which both and to the of the α and the of the βc for STAT3 high affinity receptor for IL-5 is composed of a α subunit and a βc subunit that plays an important role in to the S. H. M. Cell. Biol. 1994; PubMed Google Scholar, Miyajima T. Miyajima A. J. 1992; PubMed Scopus Google Scholar). was that JAK2 is associated with the βc N. M. Miyajima A. Cell. Biol. 1994; PubMed Google Scholar). the which the which is also in other is required for JAK2 activation. that a specific in the receptor is involved in STAT3 N. PubMed Scopus Google Scholar). the βc subunit a specific tyrosine we in which of the receptor is for STAT3 activation. we a of truncations of the βc of these is in We COS cells with these βc subunit in with the subunit, and the We found that the and able to mediate STAT3 activation in response to the of was with that the and is for STAT activation. STAT3 activation was the receptor mutant was with these data was the that the mutant was not of STAT3 in response to which activated These that the and is required for both JAK2 and STAT3 activation, the and plays an additional role in STAT3 activation. We further these that tyrosine phosphorylation of the βc receptor is not for STAT3 activation, the receptor mutant is able to receptor intracellular tyrosine phosphorylation of receptor for STAT3 activation. of the and of the receptor α and βc The homology regions are shown for the βc of homology the α subunits of receptors for IL-3, and IL-5 is also COS cells with the with the human βc chain or of the βc chain the expression for STAT3 and a and the cells for with The cells and and to of in with cells is the of The and is for STAT3 activation by with the βc chain with the the α subunit or of the α chain The and is for STAT3 activation by the of the is involved in STAT3 activation. of the α subunit and is shown in of COS cells with these α receptor with the βc subunit that mutant was to mediate STAT3 activation and a which with the in other shown that is for JAK2 activation, JAK2 is not associated with the α S. H. M. Cell. Biol. 1994; PubMed Google Scholar, N. M. Miyajima A. Cell. Biol. 1994; PubMed Google Scholar). we found that the of IL-5Rα and the of the βc subunit are essential for STAT3 demonstrate that STAT1α and der Bruggen T. E. Raaijmakers J.A.M. Lammers J.W.J. Koenderman L. Blood. PubMed Google Scholar, A.L. H. N. Miyajima A. J. PubMed Scopus Google Scholar, F. H. G. J. PubMed Scopus Google Scholar), STAT3 also plays a role in IL-5 signal the of cytokines that are to the STAT3 1994; PubMed Scopus Google Scholar, J. Blood. 1994; 84: PubMed Google Scholar, D.J. R. J. J. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar). STAT3 was the response which is activated in response to and plays a role in the activation of the response J. J. F. W. E. F. Cell. Biol. 1994; PubMed Scopus Google Scholar). on that homology to 1994; PubMed Scopus Google Scholar) and was demonstrate that STAT3 is activated in response to IL-5 both the and We these in COS cells by of the IL-5R with of the STAT We found that IL-5 induces the of STAT1α and STAT3 via the we not able to an effect of IL-5 to the of we found an in of to the The is in with which an in not in by in response to and in COS F. H. G. J. PubMed Scopus Google Scholar). that cell type-specific factors an additional role in the of the STAT We that phosphorylation is to mediate STAT3 J. E. W. H. PubMed Scopus (93) Google Scholar). IL-5 plays a restricted role in that cell type-specific are to the of STAT tyrosine phosphorylation of by IL-3 in W. A. Cell. Biol. PubMed Scopus Google Scholar). IL-3 and IL-5 the βc subunit, we found activation of by IL-5 of in COS cells. also the that cell type-specific factors are required for STAT activation. The of STAT3 in IL-5 signaling is further by the that STAT3 was tyrosine phosphorylated in cells with The tyrosine phosphorylation of STAT3 is for binding of the STAT3 to the in We found that in these cells. STAT we complex a STAT3 complex a and a STAT1α was not by both a binding was found human cells with the complex a complex composed of a and a S. M. J. J. Biol. 1994; Full Text PDF PubMed Google Scholar). IL-5 activates both STAT1α and STAT3 in COS and BaF3 cells. the by IL-5 in mature human eosinophils was not by a STAT3 The activation of STAT proteins by a IL-5 the cell with a to of on the STAT3 a role in the cells of the is by hematopoietic cells blood with IL-5 to mature by the IL-5 receptor is The of the βc subunit is in the of the GM-CSF receptor and regions that are for N. Sakamaki N. Arai Miyajima A. J. 1993; PubMed Scopus Google Scholar). of the is essential for of the and for of residues is required for activation of and shown that a of the βc subunit is required for JAK2 activation. Moreover, JAK2 is associated with the of the βc N. M. Miyajima A. Cell. Biol. 1994; PubMed Google Scholar). of the receptors for and the receptor signal an of a in for W. Young J. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar). a in the receptor that in the βc subunit is also important for JAK2 S. H. M. Cell. Biol. 1994; PubMed Google Scholar), JAK2 is not associated with N. M. Miyajima A. Cell. Biol. 1994; PubMed Google Scholar). not is the of the IL-5R in the activation of STAT using a of of the α and chain demonstrate that the membrane-proximal of both subunits are required for STAT activation. the of a specific in the receptor in the phosphorylation of N. PubMed Scopus Google Scholar). receptor mutant tyrosine phosphorylation was able to that of the βc subunit is not important for STAT3 activation. The was shown for STAT1α activation via the J. Biol. Full Text Full Text PDF PubMed Scopus Google Scholar). that the of the STAT3 to the or that the of STAT3 to the of the βc a by the of the membrane-proximal of the βc subunit for both and STAT activation. that the by which STAT proteins are activated on the of the to receptors and on specific binding for STAT proteins on the further are required to the molecular by which STAT proteins are activated via the βc subunit of the IL-5 INTRODUCTIONHematopoiesis is tightly regulated by a complex network of stromal interactions and by soluble polypeptide factors named cytokines. IL-3, 1The abbreviations used are: ILinterleukinGM-CSFgranulocyte macrophage-colony stimulating factorIL-5Rreceptor for IL-5JAKjanus kinaseSTATsignal transducer and activator of transcriptionSH domainSrc homology domainIFNinterferonhILhuman interleukinGRRγ responsive regionICAM-1intercellular adhesion molecule-1pIREpalindromic IL-6/IFN-γ response elementSIESis-inducible element. IL-5, and GM-CSF are cytokines that have diverse effects on the proliferation, differentiation, and activation of blood cells and their precursors (1Arai K.I. Lee F. Miyajima A. Miyatake S. Arai N. Yokota T. Annu. Rev. Biochem. 1990; 59: 783-836Crossref PubMed Scopus (1168) Google Scholar, 2Lopez A.F. Elliott M.J. Woodcock J. Vadas M.A. Immunol. Today. 1992; 13: 495-500Abstract Full Text PDF PubMed Scopus (127) Google Scholar, 3Ogawa M. Blood. 1993; 81: 2844-2853Crossref PubMed Google Scholar). Whereas IL-3 and GM-CSF also have effects on other hematopoietic lineages(3Ogawa M. Blood. 1993; 81: 2844-2853Crossref PubMed Google Scholar, 4Clutterbuck E.J. Hirst E.M. Sanderson C.J. Blood. 1989; 73: 1504-1512Crossref PubMed Google Scholar), the effect of IL-5 in humans is restricted to eosinophils and basophils. IL-5 is essential for eosinophil differentiation (5Campbell H.D. Tucker W.Q.J. Hort Y. Martinson M.E. Mayo G. Clutterbuck E.J. Sanderson C.J. Young I.G. Proc. Natl. Acad. Sci. U. S. A. 1987; 84: 6629-6633Crossref PubMed Scopus (266) Google Scholar, 6Sanderson C.J. Warren D.J. Strath M. J. Exp. Med. 1985; 162: 60-74Crossref PubMed Scopus (225) Google Scholar) and plays an important role in the function of mature eosinophils(7Silberstein D.S. Owen W.F. Gasson J.C. DiPersio J.F. Golde D.W. Bina J.C. Soberman R. Austen K.F. David J.R. J. Immunol. 1986; 137: 3290-3294PubMed Google Scholar, 8Lopez A.F. Sanderson C.J. Gamble J.R. Campbell H.D. Young I.G. Vadas M.A. J. Exp. Med. 1988; 167: 219-224Crossref PubMed Scopus (801) Google Scholar, 9Fujisawa T. Abu Ghazaleh R. Kita H. Sanderson C.J. Gleich G.J. J. Immunol. 1990; 144: 642-646PubMed Google Scholar, 10van der Bruggen T. Kok P.T.M. Raaijmakers J.A.M. Verhoeven A.J. Kessels R.G.C. Lammers J.W.J. Koenderman L. J. Leukocyte Biol. 1993; 53: 347-353Crossref PubMed Scopus (49) Google Scholar, 11van der Bruggen T. Kok P.T.M. Raaijmakers J.A.M. Lammers J.W.J. Koenderman L. J. Immunol. 1994; 153: 2729-2735PubMed Google Scholar). The specific effects of IL-5 on eosinophils and basophils are due to restricted expression of the low affinity IL-5Rα receptor on these cell types(12Chihara J. Plumas J. Gruart V. Tavernier J. Prin L. Capron A. Capron M. J. Exp. Med. 1990; 172: 1347-1351Crossref PubMed Scopus (93) Google Scholar, 13Ingley E. Young I.G. Blood. 1991; 78: 339-344Crossref PubMed Google Scholar). The high affinity receptor for IL-5 (IL-5R) is composed of a unique α subunit associated with a βc subunit that is shared with the receptors for IL-3 and GM-CSF(14Tavernier J. Devos R. Cornelis S. Tuypens T. Van der Heyden J. Fiers W. Plaetinck G. Cell. 1991; 66: 1175-1184Abstract Full Text PDF PubMed Scopus (493) Google Scholar). The βc subunit is essential for signal transduction(15Kitamura T. Miyajima A. Blood. 1992; 80: 84-90Crossref PubMed Google Scholar, 16Miyajima A. Mui A.L. Ogorochi T. Sakamaki Blood. 1993; PubMed Google Scholar), the α chain intracellular S. H. M. Cell. Biol. 1994; PubMed Google Scholar). the of the βc subunit by IL-3, IL-5, and GM-CSF the of these A. Mui A.L. Ogorochi T. Sakamaki Blood. 1993; PubMed Google Scholar, A. T. T. Biochem. Sci. 1992; Full Text PDF PubMed Scopus Google Scholar). signal are not and are to composed of both and differentiation is that the βc subunit, other not tyrosine N. Sakamaki N. Arai Miyajima A. J. 1993; PubMed Scopus Google Scholar, A.L. Miyajima A. Proc. Exp. Biol. Med. 1994; PubMed Scopus Google Scholar). of the events to IL-3, IL-5, and GM-CSF is of tyrosine N. Sakamaki N. Arai Miyajima A. J. 1993; PubMed Scopus Google Scholar, Miyajima T. Miyajima A. J. 1992; PubMed Scopus Google Scholar). tyrosine phosphorylation is by the activation of tyrosine T. R. J.C. Blood. 1992; 80: PubMed Google Scholar, L. R. J. Exp. Med. PubMed Scopus Google Scholar) and Y. S. H. Miyajima A. Arai Y. H. J. 1993; PubMed Scopus Google Scholar). Recent have that the of and is associated with receptors and is phosphorylated Full Text PDF PubMed Scopus Google Scholar). We and have shown that JAK2 is activated in response to IL-3, IL-5, and GM-CSF T. Proc. Natl. Acad. Sci. U. S. A. 1993; PubMed Scopus Google Scholar, der Bruggen T. E. Raaijmakers J.A.M. Lammers J.W.J. Koenderman L. Blood. PubMed Google Scholar, S. T. S. Y. Y. S. S. T. J. Exp. Med. 1994; PubMed Scopus Google Scholar) and with the membrane-proximal of the N. M. Miyajima A. Cell. Biol. 1994; PubMed Google Scholar). The of a of factors named signal and of Full Text PDF PubMed Scopus Google proteins in the signaling D.S. Proc. Natl. Acad. Sci. U. S. A. 1990; PubMed Scopus Google Scholar, T. R. Proc. Natl. Acad. Sci. U. S. A. 1992; PubMed Scopus Google Scholar). have and are involved in specific T. R. Proc. Natl. Acad. Sci. U. S. A. 1992; PubMed Scopus Google Scholar, 1994; PubMed Scopus Google Scholar, D.J. Cell. Biol. 1994; PubMed Scopus Google Scholar, J. Exp. Med. PubMed Scopus Google Scholar, F. H. M. J. 1994; 13: PubMed Scopus Google Scholar, A.L. H. N. Miyajima A. J. PubMed Scopus Google Scholar, F. H. G. J. PubMed Scopus Google Scholar, J. U. M. 1994; PubMed Scopus Google Scholar, W. A. Cell. Biol. PubMed Scopus Google Scholar). of STAT proteins a of factors that homology and a tyrosine phosphorylation Full Text PDF PubMed Scopus Google Scholar). STAT proteins in the phosphorylation on or which to the and to specific Cell. 1993; Full Text PDF PubMed Scopus Google Scholar, David M. D.S. D.S. 1993; PubMed Scopus Google Scholar, J. F. Cell. Biol. 1993; 13: PubMed Scopus Google Scholar, E. J. A. F. W. der J. Biol. 1994; Full Text PDF PubMed Google Scholar, A. M. F. W. Google Scholar). We found that STAT3 is also phosphorylated on J. E. W. H. PubMed Scopus (93) Google Scholar). phosphorylation to for the regulation of the of have shown that IL-5 activates STAT1α with an in human der Bruggen T. E. Raaijmakers J.A.M. Lammers J.W.J. Koenderman L. Blood. PubMed Google Scholar). we other STAT proteins activated by we both subunits of the IL-5 receptor with STAT cDNAs in COS cells. We that STAT3 was also activated by IL-5 in these COS cells. endogenous STAT3 was tyrosine phosphorylated and activated by in BaF3 cells expressing the (BaF3/IL5R). we using truncations of both the α and that the membrane-proximal of both subunits are for STAT3 activation.