title: Analysis of mechanisms involved in the prevention of gamma irradiation-induced apoptosis by hGM-CSF.
abstract: Human granulocyte-macrophage colony-stimulating factor (hGM-CSF) induces proliferation and sustains viability of the mouse interleukin (IL)-3 dependent lymphoid cell line BA/F3 expressing the hGM-CSF receptor. Caspase-3 like enzyme activity and DNA fragmentation were augmented by depletion of this factor from the cell, and exposure to gamma irradiation accelerated kinetics of these events. Anti gamma irradiation-induced apoptosis occurred through various mutant GM-CSF receptors and only the box1 region was essential while the C terminal region, including tyrosine residues which are required for MAPK cascade activation, was dispensable. Consistent with this notion, the addition of PD98059 had no effect on this activity thereby indicating that activation of MAPK is not essential for the activity. As expected, gamma irradiation increased p53 protein and bax mRNA levels and the presence of hGM-CSF dramatically modulated bax/bcl-X(L) ratio. The PI-3K specific inhibitor wortmannin did not affect hGM-CSF dependent anti gamma irradiation induced apoptosis nor bcl-X(L) induction, thus bcl-X(L) but not PI-3K pathway seems to be involved in hGM-CSF dependent anti gamma irradiation-induced apoptosis. It is well documented that the boxl region is essential for GM-CSF dependent activation of JAK2 and JAK2 specific inhibitor AG490 suppressed anti gamma, irradiation-induced apoptosis by hGM-CSF. An artificial JAK2 activating molecule in which extracellular and the transmembrane of beta(c) fused with whole JAK2 can sustain BA/F3 cells survival and proliferation mIL-3 independently, but these cells are susceptible to gamma irradiation. Furthermore GyrB/Jak2, which can activate STAT5 but not the MAPK cascade nor survival of BA/F3 cells, also could not prevent gamma irradiation-induced apoptosis. Although JAK2 is essential for hGM-CSF dependent anti gamma irradiation-induced apoptosis, it appeared that JAK2 does not seem sufficient for the activity.
authors.affiliation: Department of Molecular and Developmental Biology, Institute of Medical Science, University of Tokyo, Japan.
authors.forename: R
authors.initials: R
authors.lastname: Liu
authors.forename: C B
authors.initials: CB
authors.lastname: Liu
authors.forename: M G
authors.initials: MG
authors.lastname: Mohi
authors.forename: K
authors.initials: K
authors.lastname: Arai
authors.forename: S
authors.initials: S
authors.lastname: Watanabe
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D004249:DNA Damage; D053938:DNA Fragmentation / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000502:physiology; D004790:Enzyme Induction / Q000528:radiation effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D005720:Gamma Rays; D019833:Genistein / Q000494:pharmacology; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D053614:Janus Kinase 2; D020935:MAP Kinase Signaling System; D051379:Mice; D008894:Milk Proteins; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology; D011837:Radiation-Protective Agents / Q000494:pharmacology; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D011993:Recombinant Fusion Proteins / Q000494:pharmacology; D050799:STAT5 Transcription Factor; D015534:Trans-Activators / Q000502:physiology; D051020:bcl-X Protein
chemical_list: C494811:BCL2L1 protein, human; C494812:Bcl2l1 protein, mouse; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007377:Interleukin-3; D008894:Milk Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011837:Radiation-Protective Agents; D016187:Receptors, Granulocyte-Macrophage Colony-Stimulating Factor; D011993:Recombinant Fusion Proteins; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D051020:bcl-X Protein; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D019833:Genistein; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2; D020169:Caspases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one