The Fer tyrosine kinase is important for platelet-derived growth factor-BB-induced signal transducer and activator of transcription 3 (STAT3) protein phosphorylation, colony formation in soft agar, and tumor growth in vivo.

Lennartsson J, Ma H, Wardega P, Pelka K, Engström U, Hellberg C, Heldin CH

J Biol Chem 288 (22) 15736-15744 [2013-05-31; online 2013-04-15]

Fer is a cytoplasmic tyrosine kinase that is activated in response to platelet-derived growth factor (PDGF) stimulation. In the present report, we show that Fer associates with the activated PDGF β-receptor (PDGFRβ) through multiple autophosphorylation sites, i.e. Tyr-579, Tyr-581, Tyr-740, and Tyr-1021. Using low molecular weight inhibitors, we found that PDGF-BB-induced Fer activation is dependent on PDGFRβ kinase activity, but not on the enzymatic activity of Src or Jak kinases. In cells in which Fer was down-regulated using siRNA, PDGF-BB was unable to induce phosphorylation of STAT3, whereas phosphorylations of STAT5, ERK1/2, and Akt were unaffected. PDGF-BB-induced activation of STAT3 occurred also in cells expressing kinase-dead Fer, suggesting a kinase-independent adaptor role of Fer. Expression of Fer was dispensable for PDGF-BB-induced proliferation and migration but essential for colony formation in soft agar. Tumor growth in vivo was delayed in cells depleted of Fer expression. Our data suggest a critical role of Fer in PDGF-BB-induced STAT3 activation and cell transformation.

PubMed 23589302

DOI 10.1074/jbc.M113.476424

Crossref 10.1074/jbc.M113.476424

pmc: PMC3668732
pii: S0021-9258(20)45962-9