Combined In Vivo Depletion of Glycoprotein VI and C-Type Lectin-Like Receptor 2 Severely Compromises Hemostasis and Abrogates Arterial Thrombosis in Mice

Abstract

Another receptor that mediates strong platelet activation is CLEC-2, a C-type lectin-like type II transmembrane receptor, that was identified as the receptor for the platelet activating snake venom, rhodocytin.13 Interestingly, CLEC-2 is a so-called hemITAM receptor containing only a single © 2013 American Heart Association, Inc. Objective-Platelet inhibition is a major strategy to prevent acute ischemic cardiovascular and cerebrovascular events, which may, however, be associated with an increased bleeding risk. The (hem)immunoreceptor tyrosine activation motifbearing platelet receptors, glycoprotein VI (GPVI) and C-type lectin-like receptor 2 (CLEC-2), might be promising antithrombotic targets because they can be depleted from circulating platelets by antibody treatment, leading to sustained antithrombotic protection, but only moderately increased bleeding times in mice. Approach and Results-We investigated whether both (hem)immunoreceptor tyrosine activation motif-bearing receptors can be targeted simultaneously and what the in vivo consequences of such a combined therapeutic GPVI/CLEC-2 deficiency are. We demonstrate that isolated targeting of either GPVI or CLEC-2 in vivo does not affect expression or function of the respective other receptor. Moreover, simultaneous treatment with both antibodies resulted in the sustained loss of both GPVI and CLEC-2, while leaving other activation pathways intact. However, GPVI/CLEC-2-depleted mice displayed a dramatic hemostatic defect and profound impairment of arterial thrombus formation. Furthermore, a strongly diminished hemostatic response could also be reproduced in mice genetically lacking GPVI and CLEC-2. Conclusions-These

Anti–miR-148a regulates platelet FcγRIIA signaling and decreases thrombosis in vivo in mice

“…60 Neither TULA-2 nor miR-148a was indicated to affect CLEC-2 signaling by previous studies. Here we briefly investigated the role of TULA-2 and anti-miR-148a in CLEC-2 signaling via rhodocytin, a CLEC-2 ligand.…”

Targeted downregulation of platelet CLEC-2 occurs through Syk-independent internalization

“…[14][15][16] On the other hand, studies in mice have shown that the lack of platelet CLEC-2 affects thrombus stability in vitro and in vivo and protects mice from occlusive arterial thrombus formation while only moderately increasing tail bleeding times, 9,17,18 thereby establishing the receptor as a potential target for antithrombotic therapy. [17][18][19] Interestingly, however, CLEC-2 appears to share functional redundancy with GPVI, as mice deficient in both receptors display virtually abolished arterial thrombus formation and a pronounced bleeding defect. 18 Furthermore, recent evidence suggests that CLEC-2/GPVI-dependent signaling is of particular significance for the maintenance of vascular integrity under conditions of inflammation.…”

“…[17][18][19] Interestingly, however, CLEC-2 appears to share functional redundancy with GPVI, as mice deficient in both receptors display virtually abolished arterial thrombus formation and a pronounced bleeding defect. 18 Furthermore, recent evidence suggests that CLEC-2/GPVI-dependent signaling is of particular significance for the maintenance of vascular integrity under conditions of inflammation. 20 Despite its central function in multiple physiological and pathophysiological processes, not much is known about the cellular regulation of CLEC-2 in platelets.…”

CLEC-2 is required for development and maintenance of lymph nodes

“…CLEC-2 contains a half immunoreceptor tyrosine-based activation motif (ITAM), also known as a hemITAM, and signals via the tyrosine kinase Syk, 11 mediating platelet activation and thrombus formation. [12][13][14] Deficiency in CLEC-2 or its ligand Gp38/Podoplanin results in systemic edema and abnormal lymphatic The online version of this article contains a data supplement.…”