title: Cytokine rescue of p53-dependent apoptosis and cell cycle arrest is mediated by distinct Jak kinase signaling pathways.
abstract: Exposure of hematopoietic progenitors to gamma-irradiation (IR) induces p53-dependent apoptosis and a p53-independent G2/M cell cycle arrest. These responses to DNA-damage can be inhibited by treatment with cytokine growth factors. Here we report that gamma-IR-induced apoptosis and cell cycle arrest are suppressed by specific cytokines (e.g., erythropoietin and interleukin-3) and that activation of the Jak kinase is necessary and sufficient for these effects. Using myleoid cells expressing a series of erythropoietin receptor (EpoR) mutants, we have demonstrated that Jak kinase-dependent signals initiated from the membrane proximal domain of EpoR were sufficient to prevent IR-induced apoptotic cell death, but failed to prevent cell cycle arrest. Cell survival by Epo did not require activation of other known signaling pathways including PI-3 kinase, PLC-gamma, Ras or Stats. Signaling targets of Jak kinase pathways included members of the Bcl-2 family of anti-apoptotic proteins, and enforced expression of Bcl-2 or Bcl-xL was as effective as cytokine treatment in blocking IR-induced apoptosis but did not prevent growth arrest. A distinct signal derived from a membrane distal domain of EpoR is required to overcome growth arrest associated with DNA damage. These findings functionally link the Jak signaling pathway to suppression of p53-mediated cell death by cytokines and demonstrate that the apoptotic and growth arrest responses to DNA damage in hematopoietic cells are modulated by distinct, cytokine specific signal transduction pathways.
authors.affiliation: Department of Biochemistry, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA.
authors.forename: F W
authors.initials: FW
authors.lastname: Quelle
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Feng
authors.forename: D
authors.initials: D
authors.lastname: Wang
authors.forename: J L
authors.initials: JL
authors.lastname: Cleveland
authors.forename: J N
authors.initials: JN
authors.lastname: Ihle
authors.forename: G P
authors.initials: GP
authors.lastname: Zambetti
mesh_terms: D000818:Animals; D017209:Apoptosis; D002453:Cell Cycle; D002455:Cell Division; D002460:Cell Line; D004249:DNA Damage; D004789:Enzyme Activation; D004921:Erythropoietin / Q000378:metabolism; D006801:Humans; D007377:Interleukin-3 / Q000378:metabolism* / Q000494:pharmacology; D053614:Janus Kinase 2; D051379:Mice; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D017467:Receptors, Erythropoietin / Q000378:metabolism; D012710:Serum Albumin, Bovine / Q000494:pharmacology; D015398:Signal Transduction; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D051020:bcl-X Protein
chemical_list: C494811:BCL2L1 protein, human; C494812:Bcl2l1 protein, mouse; D007377:Interleukin-3; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D017467:Receptors, Erythropoietin; D016159:Tumor Suppressor Protein p53; D051020:bcl-X Protein; D004921:Erythropoietin; D012710:Serum Albumin, Bovine; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2