Disabled-2 Ser723 Phosphorylation in the Regulation of Platelet Activation and Inside-Out Signaling

Platelets are important for maintaining normal physiological haemostasis and are critical in pathological development of human diseases. One of the abundantly expressed human platelet proteins Disabled-2 (Dab2) has been implicated in platelet aggregation, fibrinogen endocytosis, Gα12/13-mediated RhoA/ROCKII activation, and the control of clotting responses, hemostasis and thrombosis. We recently unveiled that Dab2 is phosphorylated at Ser723 when human platelets were activated by the platelet agonists. The phosphorylation site is uniquely present in human but not mouse/rat Dab2. Despite we have shown that Dab2-Ser723 phosphorylation is involved in inside-out but not outside-in signaling during platelet activation, the molecular events following Dab2 Ser723 phosphorylation are still largely unknown. In this study, human platelets and genetically engineered murine platelets expressing wild type or Ser723 mutant of human Dab2 will be used as the model systems to define the mechanistic insight and functions of Dab2-Ser723 phosphorylation in platelet activation and signaling. Specifically, we will elucidate the molecular basis for the effects of Dab2-Ser723 phosphorylation on inside-out signaling of human platelets during the grant period. At the second year, we will establish mouse models with megakaryocyte/platelet lineage-restricted expression of wild type or Ser723 mutant of human Dab2 in mouse platelet by using conventional gene knock-in, CRISPR gene targeting strategy, and Cre-LoxP system. At the third year, we will define the in vivo role of Dab2 phosphorylation in platelet functions and activation by using the mouse models with platelets expressing wild type or Ser723 mutant human Dab2. This study will provide important information regarding the underlying mechanisms of platelet activation and contribute to our understanding of platelet biology, haemostasis and thrombosis.

Project ID:PC10507-0263
External Project ID:MOST105-2320-B182-030