Phosphoproteomics Nabs New FGF Receptor Targets

Science's STKE  09 Nov 2004:
Vol. 2004, Issue 258, pp. tw407
DOI: 10.1126/stke.2582004tw407

Improvements in proteomic techniques and in mass spectrometry in particular are enabling large-scale analysis of signaling proteins that are covalently modified in stimulated cells. Hinsby et al. applied the latest techniques to identify proteins that participate in signaling from the fibroblast growth factor receptor (FGFR). They used a new linear ion trap Fourier transform mass spectrometer with attomole sensitivity to detect proteins phosphorylated in response to FGF in a human cell line transfected with the FGFR. Phosphoproteins were isolated by immunoprecipitation with antibody to phosphotyrosine. Then stable isotope labeling by amino acids in cell culture (SILAC) was used with mass spectrometry to allow direct comparison of peptides from stimulated and unstimulated cells (which could be distinguished by a 6-Da shift in mass of peptides from cells incubated with [13C]Arg). Of more than 800 proteins nonspecifically present in the immunoprecipitates, 28 were identified that showed response to FGF. A number of these were proteins not previously implicated in FGR signaling, including IRS-4, GIT1 and GIT2 (GTPase-activating proteins for the Arf small GRPases), SHIP2 (SH2 domain-containing inositol phosphatase), annexins VII and XI, liver-specific bHLH-Zip transcription factor (LISCH7), and WDR6, a protein with WD40 repeats that function in protein interactions. The authors propose that the described phosphoproteomics techniques will help provide unbiased mapping of signaling networks.

A. M. Hinsby, J. V. Olsen, M. Mann, Tyrosine phosphoproteomics of fibroblast growth factor signaling. A role for insulin receptor substrate-4. J. Biol. Chem. 279, 46438-46447 (2004). [Abstract] [Full Text]