Key result
Oxidative stress activates TACE and induces shedding of key adhesion receptors in platelets via p38 MAPK signaling, rendering them functionally less active.
Oxidative stress attenuates platelet function by inducing p38-dependent shedding of key adhesion receptors via TACE activation.
Oxidative stress may impair platelet function in vivo; hypothesis-generating for p38/TACE modulation in human thrombosis.
AIMS: Oxidative stress accompanies inflammatory and vascular diseases. The objective of this study was to explore whether reactive oxygen species can activate shedding of platelet receptors and thus suppress platelet function. METHODS AND RESULTS: Hydrogen peroxide and glucose oxidase were chosen to model oxidative stress in vitro. We demonstrate that oxidative damage activated tumour necrosis factor-alpha-converting enzyme (TACE) and induced shedding of its targets, glycoprotein (GP) Ibalpha and GPV, in murine and human platelets. Also, 12-HpETE, a peroxide synthesized in the platelet lipoxygenase pathway, induced TACE-mediated receptor cleavage. The TACE activation was independent of platelet activation, as alpha-granule secretion, activation of alphaIIbbeta3, or phosphatidylserine expression was not observed. TACE activation induced by hydrogen peroxide was dependent on p38 mitogen-activated protein kinase signalling, whereas protein kinase C, phosphoinositide 3-kinase, and caspases were not involved. Inhibition of p38 cytoplasmic targets, phospholipase A(2) and heat shock protein 27, did not prevent shedding, whereas blocking 12-lipoxygenase or Src kinase slightly inhibited TACE activation. The loss of the GPIbalpha receptor induced by oxidative stress rendered platelets unable to incorporate into a growing thrombus in vivo. CONCLUSION: Oxidative stress can render platelets functionally less active by shedding key adhesion receptors via the activation of p38. This suggests that oxidative injury of platelets may attenuate their function.
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Brill et al. (2009) studied Oxidative stress and platelet function. Oxidative stress (Hydrogen peroxide and glucose oxidase) was evaluated on TACE activation and shedding of GPIbalpha and GPV. Oxidative stress activates TACE and induces shedding of key adhesion receptors in platelets via p38 MAPK signaling, rendering them functionally less active.
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