Mislocalized activation of oncogenic RTKs switches downstream signaling outcomes

Mol Cell. 2009 Oct 23;36(2):326-39. doi: 10.1016/j.molcel.2009.09.019.


Inappropriate activation of oncogenic kinases at intracellular locations is frequently observed in human cancers, but its effects on global signaling are incompletely understood. Here, we show that the oncogenic mutant of Flt3 (Flt3-ITD), when localized at the endoplasmic reticulum (ER), aberrantly activates STAT5 and upregulates its targets, Pim-1/2, but fails to activate PI3K and MAPK signaling. Conversely, membrane targeting of Flt3-ITD strongly activates the MAPK and PI3K pathways, with diminished phosphorylation of STAT5. Global phosphoproteomics quantified 12,186 phosphorylation sites, confirmed compartment-dependent activation of these pathways and discovered many additional components of Flt3-ITD signaling. The differential activation of Akt and Pim kinases by ER-retained Flt3-ITD helped to identify their putative targets. Surprisingly, we find spatial regulation of tyrosine phosphorylation patterns of the receptor itself. Thus, intracellular activation of RTKs by oncogenic mutations in the biosynthetic route may exploit cellular architecture to initiate aberrant signaling cascades, thus evading negative regulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Apoptosis / drug effects
  • Brefeldin A / pharmacology
  • Cell Compartmentation / drug effects
  • Endoplasmic Reticulum / drug effects
  • Endoplasmic Reticulum / enzymology
  • Enzyme Activation / drug effects
  • HeLa Cells
  • Humans
  • Isotope Labeling
  • Mice
  • Mitogen-Activated Protein Kinases / metabolism
  • Molecular Sequence Data
  • Oncogenes*
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphoproteins / chemistry
  • Phosphoproteins / metabolism
  • Phosphorylation / drug effects
  • Protein Structure, Tertiary
  • Proteomics
  • Proto-Oncogene Proteins c-kit / metabolism
  • Receptor Protein-Tyrosine Kinases / chemistry
  • Receptor Protein-Tyrosine Kinases / metabolism*
  • STAT5 Transcription Factor / metabolism
  • Sequence Deletion
  • Signal Transduction* / drug effects
  • Tunicamycin / pharmacology
  • fms-Like Tyrosine Kinase 3 / chemistry
  • fms-Like Tyrosine Kinase 3 / metabolism


  • Phosphoproteins
  • STAT5 Transcription Factor
  • Tunicamycin
  • Brefeldin A
  • Phosphatidylinositol 3-Kinases
  • Proto-Oncogene Proteins c-kit
  • Receptor Protein-Tyrosine Kinases
  • fms-Like Tyrosine Kinase 3
  • Mitogen-Activated Protein Kinases