Cutting Edge: Dok-1 and Dok-2 Adaptor Molecules Are Regulated by Phosphatidylinositol 5-Phosphate Production in T Cells
Guittard, Geoffrey Gerard, Audrey Dupuis-Coronas, Sophie Tronchere, Helene Mortier, Eva Favre, Cedric Olive, Daniel Zimmermann, Pascale Payrastre, Bernard Nunes, Jacques A # ×
Amer assoc immunologists
Journal of Immunology vol:182 issue:7 pages:3974-3978
Downstream of tyrosine kinase (Dok) proteins Dok-1 and Dok-2 are involved in T cell homeostasis maintenance. Dok protein tyrosine phosphorylation plays a key role in establishing negative feedback loops of T cell signaling. These structurally related adapter molecules contain a pleckstrin homology (PH) domain generally acting as a lipid/protein-interacting module. We show that the presence of this PH domain is necessary for the tyrosine phosphorylation of Dok proteins and their negative functions in T cells. We find that Dok-1/Dok-2 PH domains bind in vitro to the rare phosphoinositide species, phosphatidylinositol 5-phosphate (PtdIns5P). Dok tyrosine phosphorylation correlates with PtdIns5P production in T cells upon TCR triggering. Furthermore, we demonstrate that PtdIns5P increase regulates Dok tyrosine phosphorylation in vivo. Together, our data identify a novel lipid mediator in T cell signaling and suggest that PH-PtdIns5P interactions regulate T cell responses. The Journal of Immunology, 2009, 182: 3974-3978.