CLEC‐2 is not required for platelet aggregation at arteriolar shear

Hughes, Craig E.; Navarro-Núñez, Leyre; Finney, Brenda; Mourão-Sá, Diego; Pollitt, Alice Y.; Watson, Steve P.

doi:10.1111/j.1538-7836.2010.04006.x

Cited by 83 publications

(79 citation statements)

References 14 publications

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“…Thus, it is only when the platelets are put under more extreme conditions, such as shear rates in stenotic arteries, that this defect becomes apparent. CLEC-2, which also signals via this pathway, has been implicated in regulating thrombus stability; although this is controversial, [18][19][20] our flow adhesion findings are consistent with the in vivo observations of the Shattil group, 8 demonstrating reduced thrombus formation in arterioles of PTP-1B-deficient mice using the laser injury model. Interestingly, PTP-1B-deficient mice did not exhibit a bleeding diathesis, 8 making PTP-1B an attractive antiplatelet drug target for prevention of thrombus formation.…”

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confidence: 81%

Dominant Role of the Protein-Tyrosine Phosphatase CD148 in Regulating Platelet Activation Relative to Protein-Tyrosine Phosphatase-1B

Mori

Wang

Ellison

et al. 2012

ATVB

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Objective-The receptor-like protein-tyrosine phosphatase (PTP) CD148 and the nontransmembrane PTP1-B have been shown to be net positive regulators of Src family kinases in platelets. In the present study, we compared the relative contributions of these PTPs in platelet activation by the major glycoprotein, glycoprotein VI, α IIb β 3 , and C-type lectin-like receptor 2 (CLEC-2). Methods and Results-PTP-1B-deficient mouse platelets responded normally to the glycoprotein VI-specific agonist collagen-related peptide and antibody-mediated CLEC-2 activation. However, they exhibited a marginal reduction in α IIb β 3 -mediated Src family kinase activation and tyrosine phosphorylation. In contrast, CD148-deficient platelets exhibited a dramatic reduction in activation by glycoprotein VI and α IIb β 3 and a marginal reduction in response to activation by CLEC-2, which was further enhanced in the absence of PTP-1B. These defects were associated with reduced activation of Src family kinase and spleen tyrosine kinase, suggesting a causal relationship. Under arteriolar flow conditions, there was defective aggregate formation in the absence of PTP-1B and, to a greater extent, CD148 and a severe abrogation of both adhesion and aggregation in the absence of both PTPs. Key Words: CD148 ◼ platelets ◼ protein-tyrosine phosphatase ◼ protein-tyrosine phosphatase-1B ◼ Src tyrosine kinase Conclusion-Findings

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confidence: 81%

Dominant Role of the Protein-Tyrosine Phosphatase CD148 in Regulating Platelet Activation Relative to Protein-Tyrosine Phosphatase-1B

Mori

Wang

Ellison

et al. 2012

ATVB

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“…Platelets also express the ITAM receptor C-type lectin-2 (CLEC2), but its role in hemostasis and thrombosis is not well understood. Whereas some investigators demonstrated impaired thrombus formation in the absence of functional CLEC2 (8,9), others could not reproduce these findings (10). Platelet CLEC2, however, plays a critical role during development.…”

Section: Introductionmentioning

confidence: 81%

Platelet ITAM signaling is critical for vascular integrity in inflammation

Boulaftali¹,

Hess²,

Getz³

et al. 2013

J. Clin. Invest.

182

264

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Platelets play a critical role in maintaining vascular integrity during inflammation, but little is known about the underlying molecular mechanisms. Here we report that platelet immunoreceptor tyrosine activation motif (ITAM) signaling, but not GPCR signaling, is critical for the prevention of inflammation-induced hemorrhage. To generate mice with partial or complete defects in these signaling pathways, we developed a protocol for adoptive transfer of genetically and/or chemically inhibited platelets into thrombocytopenic (TP) mice. Unexpectedly, platelets with impaired GPCR signaling, a crucial component of platelet plug formation and hemostasis, were indistinguishable from WT platelets in their ability to prevent hemorrhage at sites of inflammation. In contrast, inhibition of GPVI or genetic deletion of Clec2, the only ITAM receptors expressed on mouse platelets, significantly reduced the ability of platelets to prevent inflammation-induced hemorrhage. Moreover, transfusion of platelets without ITAM receptor function or platelets lacking the adapter protein SLP-76 into TP mice had no significant effect on vascular integrity during inflammation. These results indicate that the control of vascular integrity is a major function of immune-type receptors in platelets, highlighting a potential clinical complication of novel antithrombotic agents directed toward the ITAM signaling pathway.

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“…The use of mAbs to selective trigger surface receptors has provided important insight into the signaling and function of different CLRs [40][41][42]. Furthermore, human CLEC-2 signaling in platelets has also been studied upon crosslinking by polyclonal antibodies [19] and our own 17D9 mAb has also been used by others to selectively trigger CLEC-2 signaling in mouse platelets [20,43]. Notably, in those studies, the anti-CLEC-2 mAb failed to induce aggregation of CLEC-2-deficient platelets, which further confirms the specificity reported here.…”

Section: Discussionmentioning

confidence: 99%

CLEC‐2 signaling via Syk in myeloid cells can regulate inflammatory responses

et al. 2011

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Myeloid cells express a plethora of C-type lectin receptors (CLRs) that can regulate immune responses. CLEC-2 belongs to the Dectin-1 sub-family of CLRs that possess an extracellular C-type lectin-like domain and a single intracellular hemITAM motif. CLEC-2 is highly expressed on mouse and human platelets where it signals via Syk to promote aggregation. We generated a monoclonal antibody (mAb) against mouse CLEC-2 and found that CLEC-2 is additionally widely expressed on leukocytes and that its expression is upregulated during inflammation. MAb-mediated crosslinking of CLEC-2 leads to hemI-TAM-dependent signaling via Syk, Ca 21 and NFAT and, in myeloid cells, modulates the effect of toll-like receptor (TLR) agonists to selectively potentiate production of IL-10. A macrophage/dendritic cell-dependent increase in IL-10 is also observed in mice given anti-CLEC-2 mAb together with LPS. Collectively, these data indicate that CLEC-2 is expressed in myeloid cells and acts as a Syk-coupled CLR able to modulate TLR signaling and inflammatory responses.Key words: CLEC-2 . C-type lectin . HemITAM . IL-10 . Syk Supporting Information available online IntroductionSignaling by some members of the C-type lectin receptor (CLR) superfamily plays a key role in innate immunity and in regulation of myeloid cell function [1,2]. A classical example is Dectin-1, which is expressed by macrophages (MØs), neutrophils and dendritic cells (DCs) and acts as a pattern recognition receptor for b-glucans present on fungal and some bacterial cell walls. Dectin-1 signals via a phospho-tyrosine-based hemITAM motif in its intracellular domain that recruits spleen tyrosine kinase (Syk) [3,4]. Dectin-1 signaling through Syk in myeloid cells can variably lead to phagocytosis, production of reactive oxygen species (ROS) and/or induction of innate response genes, including those encoding pro-inflammatory cytokines [5,6]. 3040Pro-inflammatory Dectin-1 signaling requires CARD9-dependent activation of NF-kB [7] although Dectin-1 can also signal to NF-kB via a Syk-independent pathway [8]. Although many DC types are potently activated by Dectin-1 agonists, in other myeloid cells Dectin-1 signaling only weakly activates the proinflammatory gene program [9]. In those cells, Dectin-1 acts primarily in synergy with other innate immune receptors such as toll-like receptors (TLRs) [10,11]. Notably, both Dectin-1 and CARD9 are important for resistance to fungal infection in both mice [7,12,13] and humans [14,15], indicating the importance of the CLR/Syk signaling pathway in immunity.The features of Dectin-1, including type II membrane topology, single Dectin-1-like C-type lectin-like domain and intracellular hemITAM are shared by two other CLRs, DNGR-1 (CLEC9A) and CLEC-2 (CLEC1B). DNGR-1 is selectively expressed by DCs and acts as a receptor for dead cells, facilitating cross-priming to cell-associated antigens [16]. CLEC-2 was first identified in a screen for natural killer (NK) cell receptors and its mRNA was found in myeloid cells and in some NK-cell clones [...

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CLEC‐2 is not required for platelet aggregation at arteriolar shear

Cited by 83 publications

References 14 publications

Dominant Role of the Protein-Tyrosine Phosphatase CD148 in Regulating Platelet Activation Relative to Protein-Tyrosine Phosphatase-1B

Dominant Role of the Protein-Tyrosine Phosphatase CD148 in Regulating Platelet Activation Relative to Protein-Tyrosine Phosphatase-1B

Platelet ITAM signaling is critical for vascular integrity in inflammation

CLEC‐2 signaling via Syk in myeloid cells can regulate inflammatory responses

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