title: Mitogenic signalling and substrate specificity of the Flk2/Flt3 receptor tyrosine kinase in fibroblasts and interleukin 3-dependent hematopoietic cells.
abstract: Flk2/Flt3 is a recently identified receptor tyrosine kinase expressed in brain, placenta, testis, and primitive hematopoietic cells. The mitogenic signalling potential and biochemical properties of Flk2/Flt3 have been analyzed by using a chimeric receptor composed of the extracellular domain of the human colony-stimulating factor 1 receptor and the transmembrane and cytoplasmic domains of murine Flk2/Flt3. We demonstrate that colony-stimulating factor 1 stimulation of the Flk2/Flt3 kinase in transfected NIH 3T3 fibroblasts leads to a transformed phenotype and generates a full proliferative response in the absence of other growth factors. In transfected interleukin 3 (IL-3)-dependent Ba/F3 lymphoid cells, activation of the chimeric receptor can abrogate IL-3 requirement and sustain long-term proliferation. We show that phospholipase C-gamma 1, Ras GTPase-activating protein, the p85 subunit of phosphatidylinositol 3'-kinase, Shc, Grb2, Vav, Fyn, and Src are components of the Flk2/Flt3 signal transduction pathway. In addition, we demonstrate that phospholipase C-gamma 1, the p85 subunit of phosphatidylinositol 3'-kinase, Shc, Grb2, and Src family tyrosine kinases, but not Ras GTPase-activating protein, Vav, or Nck, physically associate with the Flk2/Flt3 cytoplasmic domain. Cell-type-specific differences in tyrosine phosphorylation of p85 and Shc are observed. A comparative analysis of the Flk2/Flt3 signal cascade with those of the endogenous platelet-derived growth factor and IL-3 receptors indicates that Flk2/Flt3 displays specific substrate preferences. Furthermore, tyrosine phosphorylation of p85 and Shc is similarly affected by totally different growth factors in the same cellular background.
authors.affiliation: Department of Molecular Biology, Princeton University, New Jersey 08544-1014.
authors.forename: M
authors.initials: M
authors.lastname: Dosil
authors.forename: S
authors.initials: S
authors.lastname: Wang
authors.forename: I R
authors.initials: IR
authors.lastname: Lemischka
mesh_terms: D019870:1-Phosphatidylinositol 4-Kinase; D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D002455:Cell Division; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D020690:GTPase-Activating Proteins; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007377:Interleukin-3 / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism; D015398:Signal Transduction; D013379:Substrate Specificity; D010738:Type C Phospholipases / Q000378:metabolism; D051941:fms-Like Tyrosine Kinase 3; D020703:ras GTPase-Activating Proteins
chemical_list: D020690:GTPase-Activating Proteins; D007377:Interleukin-3; D011506:Proteins; D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D020703:ras GTPase-Activating Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); D019870:1-Phosphatidylinositol 4-Kinase; C497970:FLT3 protein, human; C497971:Flt3 protein, mouse; D011505:Protein-Tyrosine Kinases; D020794:Receptor Protein-Tyrosine Kinases; D051941:fms-Like Tyrosine Kinase 3; D016392:Proto-Oncogene Proteins pp60(c-src); D010738:Type C Phospholipases