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J Biol Chem. 2001 Jun 22;276(25):22133-9. Epub 2001 Apr 10.

Suppressor of cytokine signaling 1 interacts with the macrophage colony-stimulating factor receptor and negatively regulates its proliferation signal.

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  • 1Centre de Génétique Moléculaire et Cellulaire, Unité Mixte de Recherche CNRS 5534, 43 Boulevard du 11 Novembre 1918, 69622 Villeurbanne, France.


Macrophage colony-stimulating factor receptor (M-CSF-R) is a tyrosine kinase that regulates proliferation, differentiation, and cell survival during monocytic lineage development. Upon activation, M-CSF-R dimerizes and autophosphorylates on specific tyrosines, creating binding sites for several cytoplasmic SH2-containing signaling molecules that relay and modulate the M-CSF signal. Here we show that M-CSF-R interacts with suppressor of cytokine signaling 1 (Socs1), a negative regulator of various cytokine and growth factor signaling pathways. Using the yeast two-hybrid system, in vitro glutathione S-transferase-M-CSF-R pull-down, and in vivo coimmunoprecipitation experiments, we demonstrated a direct interaction between the SH2 domain of Socs1 and phosphorylated tyrosines 697 or 721 of the M-CSF-R kinase insert region. Moreover, Socs1 is tyrosine-phosphorylated in response to M-CSF. Ectopic expression of Socs1 in FDC-P1/MAC and EML hematopoietic cell lines decreased their growth rates in the presence of limiting concentrations of M-CSF. However, Socs1 expression did not totally suppress long term cell growth in the presence of saturating M-CSF concentrations, in contrast to other cytokines such as stem cell factor and interleukin 3. Taken together, these results suggest that Socs1 is an M-CSF-R-binding partner involved in negative regulation of proliferation signaling and that it differentially affects cytokine receptor signals.

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