c-Abl Activates Janus Kinase 2 in Normal Hematopoietic Cells

• Published in: The Journal of biological chemistry Vol. 289; no. 31; pp. 21463 - 21472
• Main Authors: Tao, Wenjing, Leng, Xiaohong, Chakraborty, Sandip N., Ma, Helen, Arlinghaus, Ralph B.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2014; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Base Sequence; Bone Marrow Cells - drug effects; Bone Marrow Cells - enzymology; Bone Marrow Cells - metabolism; Cell Line; Cell Survival; Cytokine Induction; DNA Primers; Enzyme Activation; Hematopoiesis; Interleukin-3 - pharmacology; Janus Kinase (JAK); Janus Kinase 2 - metabolism; Leukemia; Mice; Oncogene; Polymerase Chain Reaction; Proto-Oncogene Proteins c-abl - physiology; Signal Transduction; Janus Kinase (JAK); Cytokine Induction; Hematopoiesis; Leukemia; Oncogene
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M114.554501

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. Background: Jak2 mediates cytokine-stimulated physiological events, but the mechanism of its activation is still unknown. Results: IL-3 stimulated c-Abl kinase activity leading to Jak2 activation through direct interaction with c-Abl. Conclusion: c-Abl activates Jak2 in response to IL-3 in normal hematopoietic cells. Significance: Our findings reveal a novel role of c-Abl kinase in Jak2 activation.