Suppressor of cytokine signaling (SOCS)-3 protein interacts with the insulin-like growth factor-I receptor.
SOCS proteins are a class of proteins that are negative regulators of cytokine receptor signaling via the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway. In a yeast two-hybrid screen of a human fetal brain library, we have previously identified SOCS-2 as a binding partner of the activated ... IGF-I receptor (IGFIR). To test whether or not SOCS-3 also binds to the IGFIR, we cloned human SOCS-3 by reverse transcription-polymerase chain reaction from human skeletal muscle mRNA. SOCS-3 mRNA was expressed in many human fetal and adult tissues and in some human cancer cell lines (Hela, A549 pulmonary adenocarcinoma and G361 human melanoma). We found that human SOCS-3 protein interacts directly with the cytoplasmic domains of the activated IGFIR and the insulin receptor (IR) in the yeast two-hybrid assay. In GST-SOCS-3 pull-down experiments using IGFIR from mammalian cells and in immunoprecipitation experiments in which IGFIR and FLAG-SOCS-3 were transiently expressed in human embryonic kidney 293 cells, we found that SOCS-3 interacts constitutively with IGFIR in vitro and in intact cells. Unlike SOCS-2, hSOCS-3 was phosphorylated on tyrosines in response to IGF-I addition to 293 cells. We conclude that SOCS-3 binds to the IGFIR and may be a direct substrate for the receptor tyrosine kinase.
Mesh Terms:
Animals, Blotting, Northern, Brain, Cell Line, Cloning, Molecular, Cytoplasm, DNA, Complementary, Electrophoresis, Polyacrylamide Gel, Gene Library, Glutathione Transferase, Hela Cells, Humans, Insulin-Like Growth Factor I, Jurkat Cells, Ligands, Muscle, Skeletal, Phosphorylation, Plasmids, Precipitin Tests, Protein Binding, Protein Structure, Tertiary, Proteins, RNA, Messenger, Receptor, IGF Type 1, Receptor, Insulin, Recombinant Fusion Proteins, Repressor Proteins, Reverse Transcriptase Polymerase Chain Reaction, Signal Transduction, Suppressor of Cytokine Signaling Proteins, Tissue Distribution, Transcription Factors, Tumor Cells, Cultured, Two-Hybrid System Techniques, Tyrosine
Animals, Blotting, Northern, Brain, Cell Line, Cloning, Molecular, Cytoplasm, DNA, Complementary, Electrophoresis, Polyacrylamide Gel, Gene Library, Glutathione Transferase, Hela Cells, Humans, Insulin-Like Growth Factor I, Jurkat Cells, Ligands, Muscle, Skeletal, Phosphorylation, Plasmids, Precipitin Tests, Protein Binding, Protein Structure, Tertiary, Proteins, RNA, Messenger, Receptor, IGF Type 1, Receptor, Insulin, Recombinant Fusion Proteins, Repressor Proteins, Reverse Transcriptase Polymerase Chain Reaction, Signal Transduction, Suppressor of Cytokine Signaling Proteins, Tissue Distribution, Transcription Factors, Tumor Cells, Cultured, Two-Hybrid System Techniques, Tyrosine
Biochem. Biophys. Res. Commun.
Date: Nov. 11, 2000
PubMed ID: 11071852
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