Regulation of FcγRIIA signaling by TULA-2 and miR-148a. Binding of immune complexes to platelet FcγRIIA receptor leads to platelet activation and subsequent thrombotic complications resulting in heparin- and immune-induced thrombocytopenia. Platelet TULA-2 negatively regulates platelet activation downstream of FcγRIIA by diminishing spleen tyrosine kinase (Syk) phosphorylation (P). Intraplatelet TULA-2 levels therefore mediate FcγRIIA-induced platelet activation and thereby determine platelet responsiveness to heparin- or immune-mediated antigen-antibody complexes. In turn, intraplatelet TULA-2 is negatively regulated by microRNA miR-148a. Treatment of mice with anti–miR-148a results in diminished thrombotic complications in vivo.