title: Pim-1 kinase inhibits STAT5-dependent transcription via its interactions with SOCS1 and SOCS3.
abstract: Signal transducer and activator of transcription 5 (STAT5) plays a critical role in cytokine-induced survival of hematopoietic cells. One of the STAT5 target genes is pim-1, which encodes an oncogenic serine/threonine kinase. Here we demonstrate that Pim-1 inhibits STAT5-dependent transcription in cells responsive to interleukin-3, prolactin, or erythropoietin. Ectopic expression of Pim-1 in cytokine-dependent FDCP1 myeloid cells results in reduced tyrosine phosphorylation and DNA binding of STAT5, indicating that Pim-1 interferes already with the initial steps of STAT5 activation. However, the Pim-1 kinase does not directly phosphorylate or bind to STAT5. By contrast, Pim-1 interacts with suppressor of cytokine signaling 1 (SOCS1) and SOCS3 and potentiates their inhibitory effects on STAT5, most likely via phosphorylation-mediated stabilization of the SOCS proteins. Thus, both Pim and SOCS family proteins may be components of a negative feedback mechanism that allows STAT5 to attenuate its own activity.
authors.affiliation: Turku Centre for Biotechnology, University of Turku/Abo Akademi University, Turku, Finland.
authors.forename: Katriina J
authors.initials: KJ
authors.lastname: Peltola
authors.forename: Kirsi
authors.initials: K
authors.lastname: Paukku
authors.forename: Teija L T
authors.initials: TL
authors.lastname: Aho
authors.forename: Marja
authors.initials: M
authors.lastname: Ruuska
authors.forename: Olli
authors.initials: O
authors.lastname: Silvennoinen
authors.forename: Päivi J
authors.initials: PJ
authors.lastname: Koskinen
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000502:physiology; D025461:Feedback, Physiological; D051379:Mice; D008894:Milk Proteins; D022423:Myeloid Cells / Q000166:cytology / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051573:Proto-Oncogene Proteins c-pim-1; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D050799:STAT5 Transcription Factor; D000071222:Suppressor of Cytokine Signaling 1 Protein; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D015534:Trans-Activators / Q000037:antagonists & inhibitors* / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D008894:Milk Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; D050799:STAT5 Transcription Factor; C491590:Socs1 protein, mouse; C491411:Socs3 protein, mouse; D000071222:Suppressor of Cytokine Signaling 1 Protein; D000071223:Suppressor of Cytokine Signaling 3 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C496636:Pim1 protein, mouse; D017346:Protein Serine-Threonine Kinases; D051573:Proto-Oncogene Proteins c-pim-1