Negative Regulation of Mitogen-activated Protein Kinase Activation by Integrin αIIbβ3 in Platelets

Nadal, Florence; Lévy-Toledano, S; Grelac, Françoise; Caen, Jacques P.; Rosa, Jean‐Philippe; Bryckaert, Marijke

doi:10.1074/jbc.272.36.22381

Cited by 50 publications

(48 citation statements)

References 29 publications

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“…This is consistent with previous report that association of αIIbβ3 with fibrinogen inhibits ERK activation in platelet [21]. It was reported that the increase in PP2A activity induced by EGF results in inhibition of ERK2 activity in A431 cells [9].…”

Section: Discussionsupporting

confidence: 82%

Increased activity of phosphatase PP2A in the presence of the PlA2 polymorphism of αIIbβ3

Wang

Yan

Satterwhite

et al. 2008

Biochemical and Biophysical Research Communications

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Polymorphisms in αIIbβ3 are important genetic factors that alter platelet biology and have been associated with susceptibility to thromboembolic disorders. To define the molecular mechanisms that lead to variance in thrombotic diathesis dictated by the β3 polymorphism, we examined regulation of intracellular signaling by αIIbβ3, and studied the effects of a common β subunit PlA2 polymorphism. We found that PP2A regulates αIIbβ3 control of the ERK signaling in a polymorphism specific fashion. In CHO cells, exogenous expression of αIIbβ3 reduced ATPstimulated ERK phosphorylation and more so for PlA2 than PlA1. Interestingly, reduced level of ERK phosphorylation correlated with an increase in PP2A activity, with higher activity associated with PlA2 than PlA1. We tested the effect of PP2A on αIIbβ3-dependent adhesion, and found that PP2A overexpression increased cell adhesion, while phosphatase inhibitors decreased cell adhesion. We propose that PlA2 alters cell signaling at least in part by increasing β3-associated PP2A activity.

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Section: Discussionsupporting

confidence: 82%

Increased activity of phosphatase PP2A in the presence of the PlA2 polymorphism of αIIbβ3

Wang

Yan

Satterwhite

et al. 2008

Biochemical and Biophysical Research Communications

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“…We have yet to formally assess the stoichiometry of this association, but preliminary studies suggest that the majority of the ␣ IIb ␤ 3 molecules are not bound to PP1c. Nevertheless, our data show that this association regulates MLC phosphorylation, and others (19,20) have reported serine/threonine de- ) MLC (ppMLC) or MLC. B, platelets were treated with either Me 2 SO or 250 nM okadaic acid (OA) and aggregated using thrombin.…”

Section: Resultsmentioning

confidence: 67%

“…Dephosphorylation Signals by Integrin ␣ IIb ␤ 3 via an Associated PP1 33041 phosphorylation of extracellular signal-regulated kinases ERK (19) and Jun-N kinase JNK (20) upon fibrinogen binding. More importantly, these transient dephosphorylation events are essential for platelet physiology because phosphatase inhibitors impair platelet aggregation, adhesion, and spreading to fibrinogen (21,22).…”

Section: Resultsmentioning

confidence: 99%

Protein Phosphatase 1 Associates with the Integrin αIIb Subunit and Regulates Signaling

Vijayan

Liu

et al. 2004

Journal of Biological Chemistry

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Regulation of integrin activation occurs by specific interactions among cytoplasmic proteins and integrin ␣ and ␤ cytoplasmic tails. We report that the catalytic subunit of protein phosphatase 1 (PP1c) constitutively associates with the prototypic integrin ␣ IIb ␤ 3 in platelets and in cell lines overexpressing the integrin. PP1c binds directly to the cytoplasmic domain of integrin ␣ IIb subunit containing a conserved PP1c binding motif 989 KVGF 992 . Anchored PP1c is inactive, while thrombininduced platelet aggregation or fibrinogen-␣ IIb ␤ 3 engagement caused PP1c dissociation and concomitant activation as revealed by dephosphorylation of PP1c substrate, myosin light chain. Inhibition of ligand binding to activated ␣ IIb ␤ 3 blocks PP1c dissociation and represses PP1c activation. These studies reveal a previously unrecognized role for integrins whereby the ␣ subunit cytoplasmic tail localizes the machinery for initiating and temporally maintaining the regulatory signaling activity of a phosphatase.Integrin signaling mediated by reversible phosphorylation of proteins controls fundamental cellular processes like adhesion and migration. The prototypic integrin, platelet ␣ IIb ␤ 3 , undergoes affinity/avidity modulation for its ligands through the process of inside-out signaling, resulting in firm adhesion and platelet aggregation upon vascular injury. Subsequent binding of fibrinogen to integrin ␣ IIb ␤ 3 generates outside-in signaling (1). Both ␣ IIb ␤ 3 inside-out and outside-in signaling result in tyrosine or serine/threonine phosphorylation of multiple signaling proteins, serving to initiate and amplify signaling cascades that support the formation of stable platelet-platelet and platelet-extracellular matrix interactions. Cytoskeletal proteins like talin (2), and non-receptor tyrosine and serine/threonine kinases, including Src, Csk, Syk (3), protein kinase C (4), integrin-linked kinase (5), and calcium-and integrin-binding protein (6), associate with integrin ␤ and ␣ cytoplasmic tails and mediate these integrin-dependent signaling events.The net tyrosine or serine/threonine phosphorylation of a protein substrate is regulated by the activities of both protein kinases and phosphatases. While kinases and phosphorylation events during integrin mediated signaling have been clearly demonstrated, the role for phosphatases is poorly understood. Phosphatases play an essential role in dampening platelet phosphorylation events, and serine/threonine dephosphorylation of cytoskeletal proteins like cofilin, talin, and vasodilatorstimulated phosphoprotein correlates with platelet activation (7-9). Unlike the situation with kinases, only serine/threonine protein phosphatase PP2A has been reported to associate with integrin ␤ 1 (10), while only tyrosine phosphatase SHP-2 is known to associate with ␤ 3 (11). We are unaware of any reports of a phosphatase associating with an integrin ␣ subunit.PP1 is the best characterized and major serine/threonine protein phosphatase. The catalytic subunit of PP1 1 (PP1c) does not exist f...

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“…In platelets, ERKs have been shown to be activated after stimulation by thrombin, 13 collagen, 14 or phorbol esters 15 as well as to play a role during store-mediated Ca ϩϩ entry. 16 ERK2 was also shown to be downregulated by ␣ IIb ␤ 3 engaged in ligand binding or aggregation, 17 and a recent study indicated that von Willebrand factor binding to glycoprotein Ib-IX leads to ␣ IIb ␤ 3 activation via ERK2. 18 However, the upstream effectors and the downstream targets of the platelet ERK signaling pathway remain largely uncharacterized.…”

Section: Introductionmentioning

confidence: 99%

P2X1-mediated activation of extracellular signal-regulated kinase 2 contributes to platelet secretion and aggregation induced by collagen

Oury

Tóth-Zsámboki

Vermylen

et al. 2002

Blood

104

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Adenosine triphosphate (ATP) and its stable analog, ␣,␤-methylene ATP, activate the platelet P2X 1 ion channel, causing a rapid Ca ؉؉ influx. Here, we show that, in washed apyrase-treated platelets, ␣,␤-methylene ATP elicits reversible extracellular signal-regulated kinase 2 (ERK2) phosphorylation through a Ca ؉؉ -and protein kinase C-dependent pathway. In contrast, high-performance liquid chromatography-purified adenosine diphosphate (ADP) did not trigger ERK2 phosphorylation. ␣,␤-Methylene ATP also activated the ERK2 pathway in P2X 1 -transfected HEK293 cells but not in cells expressing mutated P2X 1 delL nonfunctional channels. Because ATP released from the dense granules during platelet activation contributes to platelet aggregation elicited by low doses of collagen, and because collagen causes ERK2 phosphorylation, we have investigated the role of P2X 1 -mediated ERK2 activation in these platelet responses. We found that the antagonism of P2X 1 with ADP or desensitization of this ion channel with ␣,␤-methylene ATP both resulted in impaired ERK2 phosphorylation, ATP secretion, and platelet aggregation induced by low concentrations of collagen (< 1 g/mL) without affecting the minor early dense granule release. Selective MEK1/2 inhibition by U-0126 and Ca ؉؉ chelation with EGTA (ethyleneglycoltetraacetic acid) behaved similarly, whereas the PKC inhibitor GF109203-X totally prevented collageninduced secretion and ERK2 activation. In contrast, when elicited by high collagen concentrations (2 g/mL), platelet aggregation and secretion no longer depended on P2X 1 or ERK2 activation, as shown by the lack of their inhibition by ␣,␤-methylene ATP or U-0126. We thus conclude that mild platelet stimulation with collagen rapidly releases ATP, which activates the P2X 1 -PKC-ERK2 pathway. This process enhances further degranulation of the collagen-primed granules allowing platelet aggregation to be completed. (Blood.

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Negative Regulation of Mitogen-activated Protein Kinase Activation by Integrin αIIbβ3 in Platelets

Cited by 50 publications

References 29 publications

Increased activity of phosphatase PP2A in the presence of the PlA2 polymorphism of αIIbβ3

Increased activity of phosphatase PP2A in the presence of the PlA2 polymorphism of αIIbβ3

Protein Phosphatase 1 Associates with the Integrin αIIb Subunit and Regulates Signaling

P2X1-mediated activation of extracellular signal-regulated kinase 2 contributes to platelet secretion and aggregation induced by collagen

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