Leukemia inhibitory factor-induced phosphorylation of STAP-2 on tyrosine-250 is involved in its STAT3-enhancing activity.
Signal transducing adaptor protein-2 (STAP-2) is a recently identified adaptor protein that contains Pleckstrin and Src homology 2 (SH2)-like domains as well as a YXXQ motif in its C-terminal region. Our previous studies revealed that STAP-2 binds to signal transducer and activator of transcription 3 (STAT3) and STAT5, and regulates their signaling pathways. In the present study, we identified tyrosine-250 (Tyr250) in STAP-2 as a major site of phosphorylation by v-src and Jak2, using a phospho-specific antibody against STAP-2 phosphorylated at Tyr250. Mutational analyses revealed that Tyr250 was involved in the STAT3-enhancing activity of STAP-2. We further found that leukemia inhibitory factor (LIF) stimulated STAP-2 Tyr250 phosphorylation in 293T and Hep3B cells. Moreover, endogenous STAP-2 was phosphorylated at Tyr250 following LIF stimulation of murine M1 cell line. Taken together, our findings demonstrate that endogenous STAP-2 is phosphorylated at Tyr250 and that this phosphorylation is involved in its function.
Sekine
Yuichi
Y
Department of Immunology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan.
Tsuji
Satoshi
S
Ikeda
Osamu
O
Kakisaka
Michinori
M
Sugiyama
Kenji
K
Yoshimura
Akihiko
A
Matsuda
Tadashi
T
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D019943:Amino Acid Substitution; D000818:Animals; D006801:Humans; D053605:Leukemia Inhibitory Factor / Q000378:metabolism*; D051379:Mice; D010649:Phenylalanine / Q000235:genetics; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism*
D048868:Adaptor Proteins, Signal Transducing; C507837:LIF protein, human; D053605:Leukemia Inhibitory Factor; D010750:Phosphoproteins; C413897:STAP2 protein, human; D050796:STAT3 Transcription Factor; D014443:Tyrosine; D010649:Phenylalanine