title: The molecular basis of IL-21-mediated proliferation.
abstract: Interleukin-21 (IL-21) is a type I cytokine that modulates functions of T, B, natural killer (NK), and myeloid cells. The IL-21 receptor (IL-21R) is closely related to the IL-2 receptor beta chain and is capable of transducing signals through its dimerization with the common cytokine receptor gamma chain (gamma(c)), the protein whose expression is defective in humans with X-linked severe combined immunodeficiency. To clarify the molecular basis of IL-21 actions, we investigated the role of tyrosine residues in the IL-21R cytoplasmic domain. Simultaneous mutation of all 6 tyrosines greatly diminished IL-21-mediated proliferation, whereas retention of tyrosine 510 (Y510) allowed full proliferation. Y510 efficiently mediated IL-21-induced phosphorylation of Stat1 and Stat3, but not of Stat5, and CD8(+) T cells from Stat1/Stat3 double knock-out mice exhibited decreased proliferation in response to IL-21 + IL-15. In addition, IL-21 weakly induced phosphorylation of Shc and Akt, and consistent with this, specific inhibitors of the MAPK and PI3K pathways inhibited IL-21-mediated proliferation. Collectively, these data indicate the involvement of the Jak-STAT, MAPK, and PI3K pathways in IL-21 signaling.
authors.affiliation: Laboratory of Molecular Immunology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1674, USA.
authors.forename: Rong
authors.initials: R
authors.lastname: Zeng
authors.forename: Rosanne
authors.initials: R
authors.lastname: Spolski
authors.forename: Esther
authors.initials: E
authors.lastname: Casas
authors.forename: Wei
authors.initials: W
authors.lastname: Zhu
authors.forename: David E
authors.initials: DE
authors.lastname: Levy
authors.forename: Warren J
authors.initials: WJ
authors.lastname: Leonard
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D048049:Extracellular Signal-Regulated MAP Kinases / Q000502:physiology; D019409:Interleukin-15 / Q000494:pharmacology; D007378:Interleukins / Q000494:pharmacology*; D008213:Lymphocyte Activation / Q000187:drug effects* / Q000235:genetics; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D019869:Phosphatidylinositol 3-Kinases / Q000502:physiology; D050794:STAT1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism; D050799:STAT5 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D014443:Tyrosine / Q000502:physiology; D000098546:Interleukin-21
chemical_list: D019409:Interleukin-15; D007378:Interleukins; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; C494080:Stat1 protein, mouse; C494087:Stat3 protein, mouse; D014443:Tyrosine; D019869:Phosphatidylinositol 3-Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D000098546:Interleukin-21