Interleukin-3 regulates the activity of the LYN protein-tyrosine kinase in myeloid-committed leukemic cell lines.
The lymphokine interleukin-3 (IL-3) promotes the growth and survival of immature hematopoietic cells. Previous studies have shown that IL-3 induces rapid increases in protein-tyrosine kinase (PTK) activity in IL-3--dependent cells. Unlike some other hematopoietic growth factor receptors (eg, c-fms and c-kit), however, the known subunits of the IL-3 receptor (IL-3R) lack intrinsic kinase activity. Recently, it was reported that the IL-2R (whose p75 beta-subunit shares sequence homology with a known murine IL-3R subunit and a common beta-subunit of the human IL-3R and granulocyte-macrophage colony-stimulating factor [GM-CSF] receptors) can physically associate with and regulate the activity of the SRC-family PTK, p56-LCK. Because most IL-3--dependent cells contain p53/56-LYN, but not p56-LCK, we explored the effects of IL-3 on the activities of LYN and other SRC-like PTKs in two human leukemic cell lines, AML-193 and TALL-101, which are phenotypically myeloid, and whose in vitro growth is dependent on IL-3. These cells expressed four of the eight known SRC-family proto-oncogenes: lyn, fyn, yes, and hck. When these factor-dependent leukemic cell lines were deprived of lymphokine to achieve cellular quiescence and then restimulated with IL-3, rapid increases (detectable within 1 minute and maximal by 10 minutes) were observed in the activity of the p53/56-LYN kinase, as assessed by in vitro kinase assays. In contrast, no alteration in the activities of other SRC-family PTKs present in these cells was detected after restimulation with IL-3 under the same conditions. This effect of IL-3 reflected an increase in the specific activity of the LYN kinase, because levels of the 53-Kd and 56-Kd LYN proteins were unaltered by IL-3 stimulation, as assessed by immunoblotting. Furthermore, the magnitude of these inducible increases in LYN kinase activity was dependent on the concentration of IL-3, and correlated with IL-3--induced proliferation. The IL-3--induced upregulation of LYN kinase activity may be mediated by the 120-Kd common subunit of the human IL-3 and GM-CSF receptors, because GM-CSF also stimulated marked increases in the activity of the LYN kinase, whereas granulocyte-CSF (G-CSF) did not, despite inducing cellular proliferation. These observations provide the first example of an IL-3--regulable PTK, and strongly suggest that the p53/56-LYN kinase participates in early IL-3--initiated signalling events, at least in some human leukemic cell lines.
Torigoe
T
T
Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia.
O'Connor
R
R
Santoli
D
D
Reed
J C
JC
D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D016391:Genes, src; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D007377:Interleukin-3 / Q000494:pharmacology*; D007700:Kinetics; D015470:Leukemia, Myeloid, Acute; D015459:Leukemia-Lymphoma, Adult T-Cell; D008970:Molecular Weight; D009856:Oncogene Proteins, Viral / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology*; D019061:src-Family Kinases
D007377:Interleukin-3; D009856:Oncogene Proteins, Viral; D011994:Recombinant Proteins; D016178:Granulocyte-Macrophage Colony-Stimulating Factor; D011505:Protein-Tyrosine Kinases; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases