G-protein beta gamma subunits mediate specific phosphorylation of the protein-tyrosine phosphatase SH-PTP1 induced by lysophosphatidic acid.
SH-PTP1 is a protein-tyrosine phosphatase preferentially expressed in hematopoietic cells and bearing two SH2 (src homology-2) domains. In the human megakaryocytic cell line Dami, lysophosphatidic acid (LPA) promoted a rapid increase in SH-PTP1 phosphorylation on both serine and tyrosine residues. Only tyrosine phosphorylation was significantly inhibited by pertussis toxin and by the protein kinase C inhibitor GF109203X. Moreover, SH-PTP1 was phosphorylated upon challenge with other agonists acting via G-protein-coupled receptors such as alpha-thrombin, epinephrine, and ADP, whereas the closely related protein-tyrosine phosphatase SH-PTP2 failed to share such a regulation in Dami cells. We developed an in vitro assay that reproduced LPA-dependent phosphorylation of SH-PTP1 in a cell-free system. The fusion protein glutathione S-transferase-beta-adrenergic receptor kinase 1-(495-689) or the transducin subunit Galphat-GDP, which act as specific antagonists of Gbetagamma, inhibited SH-PTP1 phosphorylation. Moreover, purified transducin Gbetagamma subunits mimicked the effect of LPA. Finally, stable expression of beta-adrenergic receptor kinase 1-(495-689) in Dami cells resulted in the inhibition of SH-PTP1 as a specific target of protein kinases linked to G-protein-coupled receptors via Gbetagamma subunits.
Gaits
F
F
Institut Fédératif de Recherche en Immunologie Cellulaire et Moléculaire, Université Paul Sabatier, Toulouse, France.
Li
R Y
RY
Bigay
J
J
Ragab
A
A
Ragab-Thomas
M F
MF
Chap
H
H
D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D047908:Intracellular Signaling Peptides and Proteins; D008246:Lysophospholipids / Q000378:metabolism*; D008301:Maleimides / Q000494:pharmacology; D010766:Phosphorylation; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D011994:Recombinant Proteins; D051552:beta-Adrenergic Receptor Kinases
D004791:Enzyme Inhibitors; D007211:Indoles; D047908:Intracellular Signaling Peptides and Proteins; D008246:Lysophospholipids; D008301:Maleimides; D011994:Recombinant Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D051552:beta-Adrenergic Receptor Kinases; 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; D019204:GTP-Binding Proteins; C070515:bisindolylmaleimide I