Association of STAT1, STAT3 and STAT5 proteins with the IL-2 receptor involves different subdomains of the IL-2 receptor beta chain.
Upon IL-2 stimulation of T lymphocytes, the IL-2 receptor (IL-2R) becomes phosphorylated on specific tyrosine residues which serve as docking sites for proteins containing SH2 or phosphotyrosine binding domains. To study the interaction of the IL-2Rbeta chain with Shc and STAT proteins, subdomains of the IL-2Rbeta chain were expressed as tyrosine-phosphorylated glutathione S-transferase fusion proteins and used to pull-down interacting proteins from Kit 225 cell lysates. These experiments provide direct biochemical evidence that binding to the IL-2R of the adaptor protein Shc requires phosphorylation of Tyr-338 in the IL-2Rbeta acidic subdomain. In addition, we report that STAT proteins that are activated by IL-2, i.e. STAT1, STAT3 and STAT5, indeed associate with the IL-2Rbeta chain. Both the A and B isoforms of STAT5 were found to associate with Tyr-510 of the IL-2Rbeta C-terminal region, depending on its phosphorylation. In contrast, STAT1 and STAT3 associated with the IL-2Rbeta chain through its acidic subdomain. These results indicate that the interaction between IL-2Rbeta and STAT1 or 3 does not require either phosphorylation of the receptor or even the presence of tyrosine residues of IL-2Rbeta. Thus, the IL-2R recruits STAT proteins through different modes of interaction.
Delespine-Carmagnat
M
M
INSERM Unit 461, Faculté de Pharmacie Paris-XI, Paris, France.
Bouvier
G
G
Bertoglio
J
J
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D001665:Binding Sites; D002460:Cell Line; D004268:DNA-Binding Proteins / Q000502:physiology*; D051380:GRB2 Adaptor Protein; D006801:Humans; D007376:Interleukin-2 / Q000494:pharmacology; D008894:Milk Proteins; D010766:Phosphorylation; D011506:Proteins / Q000378:metabolism; D015375:Receptors, Interleukin-2 / Q000737:chemistry / Q000502:physiology*; D050794:STAT1 Transcription Factor; D050796:STAT3 Transcription Factor; D050799:STAT5 Transcription Factor; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D015534:Trans-Activators / Q000502:physiology*; D025521:Tumor Suppressor Proteins; D014443:Tyrosine / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D004268:DNA-Binding Proteins; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D007376:Interleukin-2; D008894:Milk Proteins; D011506:Proteins; D015375:Receptors, Interleukin-2; C528024:SHC1 protein, human; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D050799:STAT5 Transcription Factor; C494092:STAT5A protein, human; C494095:STAT5B protein, human; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D015534:Trans-Activators; D025521:Tumor Suppressor Proteins; D014443:Tyrosine