Characterization of a Novel Integrin Binding Protein, VPS33B, Which Is Important for Platelet Activation and In Vivo Thrombosis and Hemostasis. Issue 24 (15th December 2015)

• Record Type: Journal Article
• Authors: Xiang, Binggang; Zhang, Guoying; Ye, Shaojing; Zhang, Rui; Huang, Cai; Liu, Jun; Tao, Min; Ruan, Changgeng; Smyth, Susan S.; Whiteheart, Sidney W.; Li, Zhenyu
• Is Part Of: Circulation. Volume 132:Issue 24(2015)
• Publication Date: 2015-12-15
• Subjects: blood platelets -- hemostasis -- integrins -- platelet aggregation -- signal transduction -- thrombosis -- VPS33B protein -- mouse; Blood -- Circulation -- Periodicals; Cardiovascular system -- Periodicals; Cardiology -- Periodicals; Heart -- Diseases -- Periodicals; Blood Circulation; Cardiovascular System; Vascular Diseases; 616.1
• DOI: 10.1161/CIRCULATIONAHA.115.018361
• Languages: English
• ISSNs: 0009-7322

Abstract

Abstract : Background—: Integrins are heterodimeric (α/β) membrane proteins that play fundamental roles in many biological processes, for example, cell adhesion and spreading, which are important for platelet function and hemostasis. The molecular mechanism that regulates integrin activation is not completely understood. Methods and Results—: Here, we show that VPS33B, a member of the Sec1/Munc18 family, binds directly to the integrin β subunit. Overexpression of VPS33B in Chinese hamster ovary cells potentiated αIIbβ3 outside-in signaling but not inside-out signaling. Platelets, from megakaryocyte- and platelet-specific VPS33B conditional knockout mice, had normal morphology, yet their spreading on fibrinogen was impaired and they failed to support clot retraction. Platelet aggregation and ATP secretion in response to low-dose agonists were reduced in the VPS33B knockout mice. αIIbβ3-mediated endocytosis of fibrinogen was also defective. Tail bleeding times and times to occlusion in an FeCl3 -induced thrombosis model were prolonged in the VPS33B knockout mice. Furthermore, VPS33B acted upstream of the RhoA-ROCK-MLC and Rac1-dependent pathways that lead to clot retraction and cell spreading, respectively. Conclusions—: Our work demonstrates that vesicular trafficking complexes, containing VPS33B, are a novel class of modifiers of integrin function. Our data also provide insights into the molecular mechanism and treatment of arthrogryposis, renal dysfunction, and cholestasis syndrome. Abstract : Supplemental Digital Content is available in the text.