title: c-Abl activates janus kinase 2 in normal hematopoietic cells.
abstract: Jak2 is involved in cytokine growth factor-stimulated signal transduction, but the mechanism of its activation is largely unknown. Here, we investigated Jak2 activation in a normal hematopoietic cell line, 32D mouse myeloid cells. The bimolecular fluorescence complementation studies showed that c-Abl formed a stable complex with Jak2 in live cells. Co-immunoprecipitation results showed that c-Abl bound to the βc chain of IL-3/IL-5/GM-CSF receptors. The kinase activities of both c-Abl and Jak2 were stimulated by IL-3 in 32D cells. Decreasing c-Abl protein expression in 32D cells by inducible shRNA decreased Jak2 activity and resulted in the failure of Jak2 activation in response to IL-3. Treatment of IL-3 and serum-starved 32D cells with 1 μM imatinib mysylate inhibited IL-3 stimulated kinase activities of both c-Abl and Jak2. In addition, the kinase-deficient Bcr-Abl mutant (p210K1172R) was defective for activation of Jak2 in 32D cells and impaired IL-3 independent growth, which was rescued by overexpression of c-Abl (+Abl). IL-3 efficiently inhibited apoptosis of 32Dp210K/R+Abl cells induced by imatinib mysylate but not Jak2 kinase inhibitor TG101209. In summary, our findings provide evidence that the kinase function of c-Abl and its C-terminal CT4 region is crucial for its interaction with Jak2 and its activation. c-Abl kinase activity induced by IL-3 is required for IL-3-stimulated Jak2 and Jak1 activation. Our findings reveal a novel regulatory role of c-Abl in Jak2 activation induced by IL-3 cytokine growth factor in 32D hematopoietic cells.
authors.affiliation: From the Department of Translational Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030.
authors.forename: Wenjing
authors.initials: W
authors.lastname: Tao
authors.affiliation: From the Department of Translational Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Leng
authors.affiliation: From the Department of Translational Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030.
authors.forename: Sandip N
authors.initials: SN
authors.lastname: Chakraborty
authors.affiliation: From the Department of Translational Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030.
authors.forename: Helen
authors.initials: H
authors.lastname: Ma
authors.affiliation: From the Department of Translational Molecular Pathology, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030 rarlingh@mdanderson.org.
authors.forename: Ralph B
authors.initials: RB
authors.lastname: Arlinghaus
mesh_terms: D000818:Animals; D001483:Base Sequence; D001854:Bone Marrow Cells / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival; D017931:DNA Primers; D004789:Enzyme Activation; D007377:Interleukin-3 / Q000494:pharmacology; D053614:Janus Kinase 2 / Q000378:metabolism*; D051379:Mice; D016133:Polymerase Chain Reaction; D016315:Proto-Oncogene Proteins c-abl / Q000502:physiology*
chemical_list: D017931:DNA Primers; D007377:Interleukin-3; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2; D016315:Proto-Oncogene Proteins c-abl
keywords: Cytokine Induction; Hematopoiesis; Janus Kinase (JAK); Leukemia; Oncogene