CHARACTERIZATION OF A NOVEL TYROSINE-PHOSPHORYLATED 100-KDA PROTEIN THAT BINDS TO SHP-2 AND PHOSPHATIDYLINOSITOL 3'-KINASE IN MYELOID CELLS

Fms is a tyrosine kinase-containing receptor for macrophage colony-sti mulating factor (M-CSF) that regulates survival, growth, and different iation of cells along the monocyte/macrophage lineage. M-CSF stimulati on of murine myeloid FDC-P1 cells expressing Fms resulted in the tyros ine phosphorylation of a number of signal transduction proteins, inclu ding an unidentified 100-kDa protein. This 100-kDa protein associated with the tyrosine phosphatase SHP-2 but not with the related phosphata se SHP-1. The kinetics of tyrosine phosphorylation of p100 and SHP-2 s uggest that p100 may be a direct substrate of SHP-2. p100 bound direct ly to the SH2 domains of both SHP-2 and the p85 subunit of phosphatidy linositol 3'-kinase. The 100-kDa protein did not appear to bind direct ly to Fms, Ship, Cbl, She, or Grb2, although all of these proteins wer e coimmunoprecipitated with p85 lifter M-CSF stimulation. Association of p100 with SHP-2 and p85 did not require the major autophosphorylati on sites on Fms nor binding of p85 to Fms, A tyrosine phosphorylated p rotein of 100 kDa also coprecipitated with SHP-2 from several ether my eloid cell lines after M-CSF stimulation but was not seen in immunopre cipitates from Rata fibroblasts expressing Fms. Stimulation of FDC-P1 cells with additional cytokines also resulted in coprecipitation of a 100-kDa protein with SHP-2. p100 may therefore be a common component o f the signaling pathways of cytokine receptors in myeloid cells.