Distinct spatio-temporal Ca2+ signaling elicited by integrin α2β1 and glycoprotein VI under flow

Mazzucato, M.; Cozzi, Marzia; Battiston, Monica; Jandrot‐Perrus, Martine; Mongiat, Maurizio; Marchese, Patrizia; Kunicki, Thomas J.; Ruggeri, Zaverio M.; Marco, Luigi De

doi:10.1182/blood-2008-12-193490

Cited by 36 publications

(34 citation statements)

References 44 publications

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“…Moreover, the aggregation and secretion defects in response to the GPVI-specific agonist CRP were overcome by increased CRP concentrations. It is possible that signalling induced by the collagen-binding integrin α2β1 [50, 51] is sufficient to overcome the mild GPVI-induced aggregation defect. In vivo Tspan9-deficient mice had no arterial thrombosis defects in GPVI-dependent models.…”

Section: Discussionmentioning

confidence: 99%

Tetraspanin Tspan9 regulates platelet collagen receptor GPVI lateral diffusion and activation

et al. 2016

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The tetraspanins are a superfamily of four-transmembrane proteins, which regulate the trafficking, lateral diffusion and clustering of the transmembrane proteins with which they interact. We have previously shown that tetraspanin Tspan9 is expressed on platelets. Here we have characterised gene-trap mice lacking Tspan9. The mice were viable with normal platelet numbers and size. Tspan9-deficient platelets were specifically defective in aggregation and secretion induced by the platelet collagen receptor GPVI, despite normal surface GPVI expression levels. A GPVI activation defect was suggested by partially impaired GPVI-induced protein tyrosine phosphorylation. In mechanistic experiments, Tspan9 and GPVI co-immunoprecipitated and co-localised, but super-resolution imaging revealed no defects in collagen-induced GPVI clustering on Tspan9-deficient platelets. However, single particle tracking using total internal reflection fluorescence microscopy showed that GPVI lateral diffusion was reduced by approximately 50% in the absence of Tspan9. Therefore, Tspan9 plays a fine-tuning role in platelet activation by regulating GPVI membrane dynamics.

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Section: Discussionmentioning

confidence: 99%

Tetraspanin Tspan9 regulates platelet collagen receptor GPVI lateral diffusion and activation

et al. 2016

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“…For example, the involvement of PI3K has been hypothesized based on indirect evidence with inhibitors, 22,23 but has never been documented directly. We filled this gap in information by measuring Akt phosphorylation, demonstrating the effective stimulation of PI3K by integrin ␣2␤1, and also identified the isoform implicated.…”

Section: Discussionmentioning

confidence: 99%

“…20,21 It has also been shown that integrin ␣2␤1 stimulates tyrosine kinases, including Src and Syk, as well as small GTPases such as Rac and Rap1b. [20][21][22][23][24] Based on the observation that the PI3K inhibitor wortmannin affects some platelet responses, 22,23 the stimulation of PI3K by integrin ␣2␤1 has been hypothesized, but so far this has not been demonstrated directly.…”

Section: Introductionmentioning

confidence: 99%

“…14,[17][18][19] Recruitment of integrin ␣2␤1 initiates an outside-in signaling pathway leading to platelet spreading on the extracellular matrix and to activation of integrin ␣IIb␤3, thus allowing binding of soluble fibrinogen to adherent platelets. [20][21][22][23] The organization of this intracellular signaling pathway is still poorly understood. It is very well documented that phospholipase C␥2 (PLC␥2) is activated, and leads to intracellular Ca 2ϩ increase and protein kinase C (PKC) stimulation.…”

Section: Introductionmentioning

confidence: 99%

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Role and regulation of phosphatidylinositol 3-kinase β in platelet integrin α2β1 signaling

Consonni

Cipolla

Guidetti

et al. 2012

Blood

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Integrin ␣2␤1-mediated adhesion of human platelets to monomeric type I collagen or to the GFOGER peptide caused a time-dependent activation of PI3K and Akt phosphorylation. This process was abrogated by pharmacologic inhibition of PI3K␤, but not of PI3K␥ or PI3K␣. Moreover, Akt phosphorylation was undetectable in murine platelets expressing a kinase-dead mutant of PI3K␤ (PI3K␤ KD ), but occurred normally in PI3K␥ KD platelets. Integrin ␣2␤1 failed to stimulate PI3K␤ in platelets from phospholipase C␥2 (PLC␥2)-knockout mice, and we found that intracellular Ca 2؉ linked PLC␥2 to PI3K␤ activation. Integrin ␣2␤1 also caused a time-dependent stimulation of the focal kinase Pyk2 downstream of PLC␥2 and intracellular Ca 2؉ . Whereas activation of Pyk2 occurred normally in PI3K␤ KD platelets, stimulation of PI3K␤ was strongly reduced in Pyk2-knockout mice. Neither Pyk2 nor PI3K␤ was required for ␣2␤1-mediated adhesion and spreading. However, activation of Rap1b and inside-out stimulation of integrin ␣IIb␤3 were reduced after inhibition of PI3K␤ and were significantly impaired in Pyk2-deficient platelets. Finally, both PI3K␤ and Pyk2 significantly contributed to thrombus formation under flow. These results demonstrate that Pyk2 regulates PI3K␤ downstream of integrin ␣2␤1, and document a novel role for Pyk2 and PI3K␤ in integrin ␣2␤1 promoted inside-out activation of integrin ␣IIb␤3 and thrombus formation. (Blood. 2012;119(3):847-856) IntroductionClass I PI3Ks are key signaling enzymes that phosphorylate the inositol ring of membrane phospholipids and generate different 3-phosphoinositides, important intracellular messengers that regulate several cellular processes through the downstream activation of the protein Ser/Thr kinase Akt. 1 Circulating blood platelets express all members of the class I PI3K family, which includes the PI3K␣, PI3K␤, PI3K␦, and PI3K␥ isoforms. PI3K activity is essential for platelet aggregation and thrombus formation, 1,2 and therefore these enzymes are potential novel targets for antithrombotic agents. For this reason, it is essential to recognize the precise contribution of every PI3K isoform in platelet activation induced by different extracellular agonists.Pharmacologic and genetic evidence indicates that PI3K␤ plays a predominant role in the regulation of platelet function. [3][4][5][6][7] Selective inactivation of PI3K␤ completely prevents platelet aggregation induced by the collagen receptor glycoprotein VI (GPVI) and reduces occlusive thrombus formation. 4,5 PI3K␤ is also implicated in the platelet response to agonists that stimulate G-protein coupled receptors (GPCRs) such as ADP or thromboxane A 2 (TxA 2 ). 3,4,8,9 Whereas PI3K␦ has been demonstrated to play a minor role in platelet activation, 10 PI3K␣ was recently proposed to be as important as PI3K␤ in GPVI signaling. 7 Similarly, several reports have documented that, in addition to PI3K␤, PI3K␥ is also implicated in GPCR-mediated platelet activation. 4,9,11,12 These observations are indicative of a still poorly appreciated interplay...

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“…27,37 Several studies reported a GPVI-independent pathway of integrin a 2 b 1 activation, and adhesion to collagen, in particular, seems to occur independently of GPVI signals. 42,51,52 The presence of integrin a 2 b 1 is essential for platelet adhesion and aggregation to monomeric collagen, 40 but not to fibrillar collagen, although initiation of aggregation is somewhat delayed in the absence of integrin a 2 . 40 Adhesion and aggregation to monomeric collagen, but not to fibrillar collagen, is enhanced in Pf4-Lox tg/tg platelets.…”

Section: Org Frommentioning

confidence: 99%

Lysyl oxidase is associated with increased thrombosis and platelet reactivity

Matsuura¹,

Mi²,

Koupenova³

et al. 2016

Blood

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• Mice overexpressing LOX in platelets have more severe thrombosis than normal animals.• LOX expression influences platelet adhesion to collagen. ) were generated. Pf4-Lox tg/tg mice had a normal number of platelets; however, time to vessel occlusion after endothelial injury was significantly shorter in Pf4-Lox tg/tg mice, indicating a higher propensity for thrombus formation in vivo.Exploring underlying mechanisms, we found that Pf4-Lox tg/tg platelets adhere better to collagen and have greater aggregation response to lower doses of collagen compared with controls. Platelet activation in response to the ligand for collagen receptor glycoprotein VI (cross-linked collagen-related peptide) was unaffected. However, the higher affinity of Pf4-Lox tg/tg platelets to the collagen sequence GFOGER implies that the collagen receptor integrin a 2 b 1 is affected by LOX. Taken together, our findings demonstrate that LOX enhances platelet activation and thrombosis. (Blood. 2016;127(11):1493-1501

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Distinct spatio-temporal Ca2+ signaling elicited by integrin α2β1 and glycoprotein VI under flow

Cited by 36 publications

References 44 publications

Tetraspanin Tspan9 regulates platelet collagen receptor GPVI lateral diffusion and activation

Tetraspanin Tspan9 regulates platelet collagen receptor GPVI lateral diffusion and activation

Role and regulation of phosphatidylinositol 3-kinase β in platelet integrin α2β1 signaling

Lysyl oxidase is associated with increased thrombosis and platelet reactivity

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