TULA-2 (T-Cell Ubiquitin Ligand-2) Inhibits the Platelet Fc Receptor for IgG IIA (FcγRIIA) Signaling Pathway and Heparin-Induced Thrombocytopenia in Mice. Issue 12 (December 2016)

• Record Type: Journal Article
• Authors: Zhou, Yuhang; Abraham, Shaji; Renna, Stephanie; Edelstein, Leonard C.; Dangelmaier, Carol A.; Tsygankov, Alexander Y.; Kunapuli, Satya P.; Bray, Paul F.; McKenzie, Steven E.
• Is Part Of: Arteriosclerosis, thrombosis, and vascular biology. Volume 36:Issue 12(2016)
• Publication Date: 2016-12
• Subjects: hematology -- hemostasis -- heparin -- thrombosis -- thrombocytopenia; Arteriosclerosis -- Periodicals; Thrombosis -- Periodicals; Blood-vessels -- Pathophysiology -- Periodicals; Electronic journals; 616.13
• DOI: 10.1161/ATVBAHA.116.307979
• Languages: English
• ISSNs: 1079-5642

Abstract

Abstract : Objective—: The objective of this study is to investigate the role of T-cell ubiquitin ligand-2 (TULA-2) in the platelet Fc receptor for IgG IIA (FcγRIIA) pathway and in the pathogenesis of heparin-induced thrombocytopenia (HIT). Approach and Results—: HIT is a life-threatening thrombotic disease in which IgG antibodies against the heparin–platelet factor 4 complex activate platelets via FcγRIIA. We reported previously differential expression of TULA-2 in human population was linked to FcγRIIA responsiveness. In this study, we investigated the role of TULA-2, a protein phosphatase, in the FcγRIIA pathway and HIT pathogenesis by crossing TULA-2 − /− mice with transgenic FcγRIIA +/+ mice. Ablation of TULA-2 resulted in hyperphosphorylation of spleen tyrosine kinase, linker for the activation of T cells, and phospholipase Cγ2 in platelets via FcγRIIA activation. Platelet integrin activation, granule secretion, phosphatidylserine exposure, and aggregation were also enhanced in TULA-2 − /− murine platelets. Compared with wild-type mice, TULA-2 − /− mice showed aggravated antibody-mediated thrombocytopenia, augmented thrombin generation, and shortened tail bleeding time. In contrast, there was no significant difference between TULA-2 − /− and TULA-2 +/+ platelets in platelet spreading and clot retraction. Of note, heterozygous TULA-2 +/− mice, whose platelets contained 50% as much protein as the TULA-2 +/+ platelets, showed significantly increased platelet reactivity and more severe thrombocytopenia in vivo compared with TULA-2 +/+ mice. Conclusions—: Together, the data demonstrate that not only the absence of TULA-2 but also the relative level of TULA-2 expression modulates FcγRIIA-mediated platelet reactivity and HIT in vivo. TULA-2 expression could be a valuable marker for HIT and inhibiting TULA-2 may serve as a potential therapy to reverse the bleeding adverse effect of anticoagulants. Abstract : Supplemental Digital Content is available in the text.