title: Interleukin-2 Receptor β Thr-450 Phosphorylation Is a Positive Regulator for Receptor Complex Stability and Activation of Signaling Molecules.
abstract: T, B, and natural killer cells are required for normal immune response and are regulated by cytokines such as IL-2. These cell signals are propagated following receptor-ligand engagement, controlling recruitment and activation of effector proteins. The IL-2 receptor β subunit (IL-2Rβ) serves in this capacity and is known to be phosphorylated. Tyrosine phosphorylation of the β chain has been studied extensively. However, the identification and putative regulatory roles for serine and threonine phosphorylation sites have yet to be fully characterized. Using LC-MS/MS and phosphospecific antibodies, a novel IL-2/IL-15 inducible IL-2Rβ phosphorylation site (Thr-450) was identified. IL-2 phosphokinetic analysis revealed that phosphorylation of IL-2Rβ Thr-450 is rapid (2.5 min), transient (peaks at 15 min), and protracted compared with receptor tyrosine phosphorylation and occurs in multiple cell types, including primary human lymphocytes. Pharmacological and siRNA-mediated inhibition of various serine/threonine kinases revealed ERK1/2 as a positive regulator, whereas purified protein phosphatase 1 (PP1), dephosphorylated Thr-450 in vitro. Reconstitution assays demonstrated that Thr-450 is important for regulating IL-2R complex formation, recruitment of JAK3, and activation of AKT and ERK1/2 and a transcriptionally active STAT5. These results provide the first evidence of the identification and functional characterization for threonine phosphorylation of an interleukin receptor.
authors.affiliation: Department of Biological Sciences and Border Biomedical Research Center, The University of Texas at El Paso, El Paso, Texas 79968.
authors.forename: Blanca E
authors.initials: BE
authors.lastname: Ruiz-Medina
authors.affiliation: Department of Biological Sciences and Border Biomedical Research Center, The University of Texas at El Paso, El Paso, Texas 79968.
authors.forename: Jeremy A
authors.initials: JA
authors.lastname: Ross
authors.affiliation: Department of Biological Sciences and Border Biomedical Research Center, The University of Texas at El Paso, El Paso, Texas 79968. Electronic address: rkirken@utep.edu.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kirken
mesh_terms: D000595:Amino Acid Sequence; D002460:Cell Line; D005786:Gene Expression Regulation; D006801:Humans; D007376:Interleukin-2 / Q000235:genetics / Q000378:metabolism*; D053646:Interleukin-2 Receptor beta Subunit / Q000235:genetics / Q000378:metabolism*; D053616:Janus Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010766:Phosphorylation; D054645:Protein Phosphatase 1 / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D050799:STAT5 Transcription Factor / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction; D013912:Threonine / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism
chemical_list: D007376:Interleukin-2; D053646:Interleukin-2 Receptor beta Subunit; D034741:RNA, Small Interfering; D050799:STAT5 Transcription Factor; D013912:Threonine; D014443:Tyrosine; D012694:Serine; C507933:JAK3 protein, human; D053616:Janus Kinase 3; D051057:Proto-Oncogene Proteins c-akt; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D054645:Protein Phosphatase 1
keywords: JAK; STAT transcription factor; cell signaling; interleukin 2; lymphocyte; protein kinase; protein phosphatase; receptor phosphorylation; serine/threonine; signal transduction