Specificity of interleukin-2 receptor gamma chain superfamily cytokines is mediated by insulin receptor substrate-dependent pathway.
Interleukins 9 (IL-9) and 4 are cytokines within the IL-2 receptor gamma chain (IL-2R gamma) superfamily that possess similar and unique biological functions. The signaling mechanisms, which may determine cytokine specificity and redundancy, are not well understood. IRS proteins are tyrosine-phosphorylated following IL-9 and IL-4 stimulation, a process in part mediated by JAK tyrosine kinases (Yin, T. G., Keller, S. R., Quelle, F. W., Witthuhn, B. A., Tsang, M. L., Lienhard, G. E., Ihle, J. N., and Yang, Y. C. (1995) J. Biol. Chem. 270, 20497--20502). In the present study, we used 32D cells stably transfected with insulin receptor (32D(IR)), which do not express any IRS proteins, as a model system to study the requirement of different structural domains of IRS proteins in IL-9- and IL-4-mediated functions. Overexpression of IRS-1 and IRS-2, but not IRS-4, induced proliferation of 32D(IR) cells in response to IL-9. The pleckstrin homology (PH) domain of IRS proteins is required for IRS-mediated proliferation stimulated by IL-9. The phosphotyrosine binding and Shc and IRS-1 NPXY binding domains are interchangeable for IRS to transduce the proliferative effect of IL-4. Therefore, the PH domain plays different roles in coupling IRS proteins to activated IL-9 and IL-4 receptors. The role of IRS proteins in determining cytokine specificity was corroborated by their ability to interact with different downstream signaling molecules. Although phosphatidylinositol 3' -kinase (PI3K) and Grb-2 interact with tyrosine-phosphorylated IRS proteins, Shp-2 only binds to IRS proteins following IL-4, but not IL-9, stimulation. Although PI3K activity is necessary for the IRS-1/2-mediated proliferative effect of IL-9 and IL-4, Akt activation is only required for cell proliferation induced by IL-4, but not IL-9. These data suggest that IRS-dependent signaling pathways work by recruiting different signaling molecules to determine specificity of IL-2R gamma superfamily cytokines.
Xiao
Hui
H
Department of Pharmacology and Cancer Center, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965, USA.
Yin
Tinggui
T
Wang
Xin-Yuan
XY
Uchida
Tohru
T
Chung
Jin
J
White
Morris F
MF
Yang
Yu-Chung
YC
D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs; D000818:Animals; D002455:Cell Division; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D051380:GRB2 Adaptor Protein; D055504:Insulin Receptor Substrate Proteins; D015847:Interleukin-4 / Q000378:metabolism*; D016906:Interleukin-9 / Q000378:metabolism*; D051379:Mice; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism; D015375:Receptors, Interleukin-2 / Q000737:chemistry* / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D014443:Tyrosine / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D016207:Cytokines; D004791:Enzyme Inhibitors; D051380:GRB2 Adaptor Protein; C495949:Grb2 protein, mouse; D055504:Insulin Receptor Substrate Proteins; D016906:Interleukin-9; C491531:Irs4 protein, mouse; D010750:Phosphoproteins; D011506:Proteins; D015375:Receptors, Interleukin-2; D015847:Interleukin-4; D014443:Tyrosine; D019869:Phosphatidylinositol 3-Kinases