title: STAT5 requires the N-domain for suppression of miR15/16, induction of bcl-2, and survival signaling in myeloproliferative disease.
abstract: Phosphorylated signal transducer and activator of transcription 5 (STAT5) is a biomarker and potential molecular target for hematologic malignancies. We have shown previously that lethal myeloproliferative disease (MPD) in mice mediated by persistently activated STAT5 (STAT5a(S711F)) requires the N-domain, but the mechanism was not defined. We now demonstrate by retrovirally complementing STAT5ab(null/null) primary mast cells that relative to wild-type STAT5a, STAT5a lacking the N-domain (STAT5aDeltaN) ineffectively protected against cytokine withdrawal-induced cell death. Both STAT5a and STAT5aDeltaN bound to a site in the bcl-2 gene and both bound near the microRNA 15b/16 cluster. However, only STAT5a could effectively induce bcl-2 mRNA and reciprocally suppress miR15b/16 leading to maintained bcl-2 protein levels. After retroviral complementation of STAT5ab(null/null) fetal liver cells and transplantation, persistently active STAT5a(S711F) lacking the N-domain (STAT5aDeltaN(S711F)) was insufficient to protect c-Kit(+)Lin(-)Sca-1(+) (KLS) cells from apoptosis and unable to induce bcl-2 expression, whereas STAT5a(S711F) caused robust KLS cell expansion, induction of bcl-2, and lethal MPD. Severe attenuation of MPD by STAT5aDeltaN(S711F) was reversed by H2k/bcl-2 transgenic expression. Overall, these studies define N-domain-dependent survival signaling as an Achilles heel of persistent STAT5 activation and highlight the potential therapeutic importance of targeting STAT5 N-domain-mediated regulation of bcl-2 family members.
authors.affiliation: Department of Medicine, Division of Hematology/Oncology, Case Western Reserve University, Cleveland, OH 44106-7284, USA.
authors.forename: Geqiang
authors.initials: G
authors.lastname: Li
authors.forename: Kristy L
authors.initials: KL
authors.lastname: Miskimen
authors.forename: Zhengqi
authors.initials: Z
authors.lastname: Wang
authors.forename: Xiu Yan
authors.initials: XY
authors.lastname: Xie
authors.forename: Jennifer
authors.initials: J
authors.lastname: Brenzovich
authors.forename: John J
authors.initials: JJ
authors.lastname: Ryan
authors.forename: William
authors.initials: W
authors.lastname: Tse
authors.forename: Richard
authors.initials: R
authors.lastname: Moriggl
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Bunting
mesh_terms: D000818:Animals; D002470:Cell Survival / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic; D006412:Hematopoietic Stem Cells / Q000473:pathology / Q000502:physiology; D007438:Introns / Q000502:physiology; D008565:Membrane Proteins / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D035683:MicroRNAs / Q000378:metabolism*; D009019:Morphinans / Q000378:metabolism; D009196:Myeloproliferative Disorders / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D017434:Protein Structure, Tertiary; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics*; D012323:RNA Processing, Post-Transcriptional / Q000502:physiology; D050799:STAT5 Transcription Factor / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology
chemical_list: C452880:Atp5md protein, rat; D008565:Membrane Proteins; D035683:MicroRNAs; C544301:Mirn15a microRNA, mouse; C522604:Mirn16 microRNA, mouse; D009019:Morphinans; D019253:Proto-Oncogene Proteins c-bcl-2; D050799:STAT5 Transcription Factor; C494093:Stat5a protein, mouse; C494096:Stat5b protein, mouse; C013757:Mr 1257 MS