Platelet autophagic machinery involved in thrombosis through a novel linkage of AMPK-MTOR to sphingolipid metabolism

  • Chao Chien Chang (Contributor)
  • Yuan-Chin Hsiung (Contributor)
  • Thanasekaran Jayakumar (Contributor)
  • Kuan Hong Lin (Contributor)
  • Cheng-ying Hsieh (Creator)
  • Nguyen Thi Thu Trang (Contributor)
  • Cheng-Yang Lee (Creator)
  • Ray-Jade Chen (Contributor)
  • Tzu-Hao Chang (Contributor)
  • Wan-Jung Lu (Contributor)
  • Chun A. Changou (Creator)
  • Tzu Yin Lee (Creator)
  • Joen-Rong Sheu (Contributor)
  • Chih Hao Yang (Contributor)



Basal macroautophagy/autophagy has recently been found in anucleate platelets. Platelet autophagy is involved in platelet activation and thrombus formation. However, the mechanism underlying autophagy in anucleate platelets require further clarification. Our data revealed that LC3-II formation and SQSTM1/p62 degradation were noted in H<sub>2</sub>O<sub>2</sub>-activated human platelets, which could be blocked by 3-methyladenine and bafilomycin A<sub>1</sub>, indicating that platelet activation may cause platelet autophagy. AMPK phosphorylation and MTOR dephosphorylation were also detected, and block of AMPK activity by the AMPK inhibitor dorsomorphin could reverse SQSTM1 degradation and LC3-II formation. Moreover, autophagosome formation was observed through transmission electron microscopy and deconvolution microscopy. These findings suggest that platelet autophagy was induced partly through the AMPK-MTOR pathway. In addition, increased LC3-II expression occurred only in H<sub>2</sub>O<sub>2</sub>-treated <i>Atg5</i><sup>f/f</sup> platelets, but not in H<sub>2</sub>O<sub>2</sub>-treated <i>atg5</i><sup>−/−</sup> platelets, providing further evidence that platelet autophagy occurs during platelet activation. <i>atg5</i><sup>−/−</sup> platelets also exhibited a lower aggregation in response to agonists, and platelet-specific <i>atg5</i><sup>−/−</sup> mice exhibited delayed thrombus formation in mesenteric microvessles and decreased mortality rate due to pulmonary thrombosis. Notably, metabolic analysis revealed that sphingolipid metabolism is involved in platelet activation, as evidenced by observed several altered metabolites, which could be reversed by dorsomorphin. Therefore, platelet autophagy and platelet activation are positively correlated, partly through the interconnected network of sphingolipid metabolism. In conclusion, this study for the first time demonstrated that AMPK-MTOR signaling could regulate platelet autophagy. A novel linkage between AMPK-MTOR and sphingolipid metabolism in anucleate platelet autophagy was also identified: platelet autophagy and platelet activation are positively correlated.
Date made available2021
PublisherTaylor & Francis

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