Activation of Src kinases p53/56lyn and p59hck by p210bcr/abl in myeloid cells.
Chronic myeloid leukemia is characterized by the Philadelphia (Ph1) translocation t(9;22) that generates a hybrid gene, bcr/abl, translated to a Mr210,000 tyrosine kinase (p210bcr/abl) with transforming activity for hematopoietic cells. Hematopoietic cell transformation by p2l0bcr/abl seems to involve activation of the Ras signaling pathway by at least two different signaling intermediates, growth factor receptor-bound protein 2 and Src homology and collagen protein, but additional signaling proteins are likely to be required as well. In an effort to identify additional phosphoproteins activated by p210bcr/abl, we studied the murine, interleukin 3-dependent, myeloid cell line, 32D, and a bcr/abl-transfected, factor-independent subline, 32Dp210. The analysis of whole-cell lysates of 32D and 32Dp210 cells showed that several proteins with a molecular weight of Mr50,000-60,000 were phosphorylated on tyrosine residues in 32Dp210 cells. Because Src family kinases have an apparent molecular weight of Mr50,000-60,000, we asked whether they could become activated by p2l0bcr/abl. Two Src family kinases, p53/56lyn and p59hck, showed a severalfold higher phosphokinase activity in 32Dp210 cells than in 32D cells. Coimmunoprecipitation experiments with anti-Lyn, anti-Hck, and anti-Abl antibodies demonstrated an intracellular association of p210bcr/abl with p53/56lyn and p59hck. Moreover, the phosphokinase activity of p53/56lyn was higher in bcr/abl-positive myeloid cell lines (K562, BV173, and LAMA84) than in the bcr/abl-negative myeloid cell line JOSK-M. In conclusion, the results show that p210bcr/abl induces the activation of at least two Src family kinases, P53/56lyn and p59hck, in myeloid cells. These findings extend the range of potential targets of p210bcr/abl that might mediate its transforming effects.
Danhauser-Riedl
S
S
Medizinische Klinik, Klinikam Innenstadt, Universität München, Germany.
Warmuth
M
M
Druker
B J
BJ
Emmerich
B
B
Hallek
M
M
D003600:Cytosol / Q000378:metabolism; D004789:Enzyme Activation; D016044:Fusion Proteins, bcr-abl / Q000096:biosynthesis / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D007377:Interleukin-3 / Q000494:pharmacology; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000201:enzymology*; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011233:Precipitin Tests; D014162:Transfection; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism*
D007377:Interleukin-3; D010750:Phosphoproteins; D014443:Tyrosine; D016044:Fusion Proteins, bcr-abl; D019061:src-Family Kinases