Erythropoietin induces the tyrosine phosphorylation of GAB1 and its association with SHC, SHP2, SHIP, and phosphatidylinositol 3-kinase.
Five tyrosine-phosphorylated proteins with molecular masses of 180, 145, 116, 100, and 70 kD are associated with phosphatidylinositol 3-kinase (PI 3-kinase) in erythropoietin (Epo)-stimulated UT-7 cells. The 180- and 70-kD proteins have been previously shown to be IRS2 and the Epo receptor. In this report, we show that the 116-kD protein is the IRS2-related molecular adapter, GAB1. Indeed, Epo induced the transient tyrosine phosphorylation of GAB1 in UT-7 cells. Both kinetics and Epo dose-response experiments showed that GAB1 tyrosine phosphorylation was a direct consequence of Epo receptor activation. After tyrosine phosphorylation, GAB1 associated with the PI 3-kinase, the phosphotyrosine phosphatase SHP2, the phosphatidylinositol 3,4,5 trisphosphate 5-phosphatase SHIP, and the molecular adapter SHC. GAB1 was also associated with the molecular adapter GRB2 in unstimulated cells, and this association dramatically increased after Epo stimulation. Thus, GAB1 could be a scaffold protein able to couple the Epo receptor activation with the stimulation of several intracellular signaling pathways. Epo-induced tyrosine phosphorylation of GAB1 was also observed in normal human erythroid progenitors isolated from cord blood. Granulocyte-macrophage colony-stimulating factor (GM-CSF) and thrombopoietin (TPO) also induced the tyrosine phosphorylation of GAB1 in UT-7 cells, indicating that this molecule participates in the signal transduction of several cytokine receptors.
Lecoq-Lafon
C
C
Institut Cochin de Génétique Moléculaire (ICGM), Institut National de la Santé et de la Recherche Médicale (INSERM U363), France.
Verdier
F
F
Fichelson
S
S
Chrétien
S
S
Gisselbrecht
S
S
Lacombe
C
C
Mayeux
P
P
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D004921:Erythropoietin / Q000494:pharmacology*; D005312:Fetal Blood; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007938:Leukemia; D008970:Molecular Weight; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases; D010750:Phosphoproteins / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D014162:Transfection; D014407:Tumor Cells, Cultured; D018909:src Homology Domains
D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; C098587:GAB1 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D011506:Proteins; D011994:Recombinant Proteins; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D004921:Erythropoietin; D019000:Phosphotyrosine; D019869:Phosphatidylinositol 3-Kinases; D010744:Phosphoric Monoester Hydrolases; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; C098706:INPPL1 protein, human; D000072183:Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases