RhoG Protein Regulates Glycoprotein VI-Fc Receptor γ-Chain Complex-mediated Platelet Activation and Thrombus Formation

Kim, Soochong; Dangelmaier, Carol; Bhavanasi, Dheeraj; Meng, Shu; Wang, Hong; Goldfinger, Lawrence E.; Kunapuli, Satya P.

doi:10.1074/jbc.m113.504928

Cited by 21 publications

(28 citation statements)

References 52 publications

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“…2 PAR-1 activating peptide SFLLRN and PAR-4 activating peptide AYPGKF activate both G q and G 12/13 pathways, leading to a calcium-dependent and calcium-independent shape change and platelet aggregation. As generally recognized, 10 μM SFLLRN or 100 μM AYPGKF caused full platelet aggregation 36 (►Fig. 1A,B); at 50 nM, the Gq inhibitor YM-254890 also abolished platelet aggregation induced by AYPGKF and SFLLRN.…”

Section: Combined Gi and G 12/13 Signaling Induces Human Platelet Aggsupporting

confidence: 63%

PAK Membrane Translocation and Phosphorylation Regulate Platelet Aggregation Downstream of Gi and G12/13 Pathways

Zhang

Zheng

et al. 2020

Thromb Haemost

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Platelet activation plays a pivotal role in physiological hemostasis and pathological thrombosis causing heart attack and stroke. Previous studies conclude that simultaneous activation of Gi and G12/13 signaling pathways is sufficient to cause platelet aggregation. However, using Gq knockout mice and Gq-specific inhibitors, we here demonstrated that platelet aggregation downstream of coactivation of Gi and G12/13 depends on agonist concentrations; coactivation of Gi and G12/13 pathways only induces platelet aggregation under higher agonist concentrations. We confirmed Gi and G12/13 pathway activation by showing cAMP (cyclic adenosine monophosphate) decrease and RhoA activation in platelets stimulated at both low and high agonist concentrations. Interestingly, we found that though Akt and PAK (p21-activated kinase) translocate to the platelet membrane upon both low and high agonist stimulation, membrane-translocated Akt and PAK only phosphorylate at high agonist concentrations, correlating well with platelet aggregation downstream of concomitant Gi and G12/13 pathway activation. PAK inhibitor abolishes Akt phosphorylation, inhibits platelet aggregation in vitro and arterial thrombus formation in vivo. We propose that the PAK-PI3K/Akt pathway mediates platelet aggregation downstream of Gi and G12/13, and PAK may represent a potential antiplatelet and antithrombotic target.

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Section: Combined Gi and G 12/13 Signaling Induces Human Platelet Aggsupporting

confidence: 63%

PAK Membrane Translocation and Phosphorylation Regulate Platelet Aggregation Downstream of Gi and G12/13 Pathways

Zhang

Zheng

et al. 2020

Thromb Haemost

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“…NK cells can also induce allograft injury via direct mechanisms (antibody-dependent cell-mediated cytotoxicity) and indirect mechanisms (cytokine production to activate other leucocytes) (Rocha et al 2003;Murata & Baldwin 2009). Syk is required for platelet activation and thrombosis via glycoprotein VI-FccR-mediated signalling (Kim et al 2013;Ozaki et al 2013), and Syk inhibitor treatment has been shown to suppress thrombosis and renal injury in antibody-dependent native kidney disease (Ryan et al 2011). Finally, thrombosis is an important mechanism of allograft injury (Meehan et al 2003;Murata & Baldwin 2009).…”

Section: Discussionmentioning

confidence: 99%

“…Finally, thrombosis is an important mechanism of allograft injury (Meehan et al 2003;Murata & Baldwin 2009). Syk is required for platelet activation and thrombosis via glycoprotein VI-FccR-mediated signalling (Kim et al 2013;Ozaki et al 2013), and Syk inhibitor treatment has been shown to suppress thrombosis and renal injury in antibody-dependent native kidney disease (Ryan et al 2011). Thus, inhibition of platelet activation may also have contributed to the reduction in capillary thrombosis seen with CC0482417 treatment of renal allografts.…”

Section: Discussionmentioning

confidence: 99%

Spleen tyrosine kinase contributes to acute renal allograft rejection in the rat

Chandran

Tesch

Han

et al. 2014

Int J Experimental Path

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Kidney allografts induce strong T-cell and antibody responses which mediate acute rejection. Spleen tyrosine kinase (Syk) is expressed by most leucocytes, except mature T cells, and is involved in intracellular signalling following activation of the Fcγ-receptor, B-cell receptor and some integrins. A role for Syk signalling has been established in antibody-dependent native kidney disease, but little is known of Syk in acute renal allograft rejection. Sprague-Dawley rats underwent bilateral nephrectomy and received an orthotopic Wistar renal allograft. Recipient rats were treated with a Syk inhibitor (CC0482417, 30 mg/kg/bid), or vehicle, from 1 h before surgery until being killed 5 days later. Vehicle-treated recipients developed severe allograft failure with marked histologic damage in association with dense leucocyte infiltration (T cells, macrophages, neutrophils and NK cells) and deposition of IgM, IgG and C3. Immunostaining identified Syk expression by many infiltrating leucocytes. CC0482417 treatment significantly improved allograft function and reduced histologic damage, although allograft injury was still clearly evident. CC0482417 failed to prevent T-cell infiltration and activation within the allograft. However, CC0482417 significantly attenuated acute tubular necrosis, infiltration of macrophages and neutrophils and thrombosis of peritubular capillaries. In conclusion, this study identifies a role for Syk in acute renal allograft rejection. Syk inhibition may be a useful addition to T-cell-based immunotherapy in renal transplantation.

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“…These experiments were performed as described previously [25]. Adult mice (aged 10-12 weeks) were anesthetized by intraperitoneal injection of pentobarbital (40 mg kg À1 ), and FeCl 3 -induced thrombosis was assessed as described previously [30].…”

Section: Platelet Spreading and Clot Retractionmentioning

confidence: 99%

TC21/RRas2 regulates glycoprotein VI–FcRγ‐mediated platelet activation and thrombus stability

Janapati

Wurtzel

Dangelmaier

et al. 2018

Journal of Thrombosis and Haemostasis

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Background Many RAS family small GTPases are expressed in platelets, including RAC, RHOA, RAP, and HRAS/NRAS/RRAS1, but most of their signaling and cellular functions remain poorly understood. Like RRAS1, TC21/RRAS2 reverses HRAS-induced suppression of integrin activation in CHO cells. However, a role for TC21 in platelets has not been explored. Objectives To determine TC21 expression in platelets, TC21 activation in response to platelet agonists, and roles of TC21 in platelet function in in vitro and in vivo thrombosis. Results We demonstrate that TC21 is expressed in human and murine platelets, and is activated in response to agonists for the glycoprotein (GP) VI-FcRγ immunoreceptor tyrosine-based activation motif (ITAM)-containing collagen receptor, in an Src-dependent manner. GPVI-induced platelet aggregation, integrin α β activation, and α-granule and dense granule secretion, as well as phosphorylation of Syk, phospholipase Cγ2, AKT, and extracellular signal-regulated kinase, were inhibited in TC21-deficient platelets ex vivo. In contrast, these responses were normal in TC21-deficient platelets following stimulation with P2Y, protease-activated receptor 4 and C-type lectin receptor 2 receptor agonists, indicating that the function of TC21 in platelets is GPVI-FcRγ-ITAM-specific. TC21 was required for GPVI-induced activation of Rap1b. TC21-deficient mice did not show a significant delay in injury-induced thrombosis as compared with wild-type controls; however, thrombi were unstable. Hemostatic responses showed similar effects. Conclusions TC21 is essential for GPVI-FcRγ-mediated platelet activation and for thrombus stability in vivo via control of Rap1b and integrins.

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RhoG Protein Regulates Glycoprotein VI-Fc Receptor γ-Chain Complex-mediated Platelet Activation and Thrombus Formation

Cited by 21 publications

References 52 publications

PAK Membrane Translocation and Phosphorylation Regulate Platelet Aggregation Downstream of Gi and G12/13 Pathways

PAK Membrane Translocation and Phosphorylation Regulate Platelet Aggregation Downstream of Gi and G12/13 Pathways

Spleen tyrosine kinase contributes to acute renal allograft rejection in the rat

TC21/RRas2 regulates glycoprotein VI–FcRγ‐mediated platelet activation and thrombus stability

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