title: Oxidative stress activates ADAM17/TACE and induces its target receptor shedding in platelets in a p38-dependent fashion.
abstract: OBJECTIVE
  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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Immune Disease Institute, 3 Blackfan Circle, 3rd Floor, Boston, MA 02115, USA.
authors.forename: Alexander
authors.initials: A
authors.lastname: Brill
authors.forename: Anil K
authors.initials: AK
authors.lastname: Chauhan
authors.forename: Matthias
authors.initials: M
authors.lastname: Canault
authors.forename: Meghan T
authors.initials: MT
authors.lastname: Walsh
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Bergmeier
authors.forename: Denisa D
authors.initials: DD
authors.lastname: Wagner
mesh_terms: D051722:ADAM Proteins / Q000502:physiology*; D000072198:ADAM17 Protein; D000818:Animals; D001792:Blood Platelets / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D015289:Leukotrienes / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018384:Oxidative Stress; D054467:Phospholipases A2 / Q000502:physiology; D010973:Platelet Adhesiveness; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology*
chemical_list: D015289:Leukotrienes; D008562:Membrane Glycoproteins; D019038:Platelet Glycoprotein GPIb-IX Complex; C094990:adhesion receptor; C021201:12-HPETE; D006861:Hydrogen Peroxide; D048051:p38 Mitogen-Activated Protein Kinases; D054467:Phospholipases A2; D051722:ADAM Proteins; D000072198:ADAM17 Protein; C000606462:ADAM17 protein, human; C000606463:Adam17 protein, mouse