Mechanisms of sphingosine and sphingosine 1-phosphate generation in human platelets

Motohiro Tani, Takamitsu Sano, Makoto Ito, Yasuyuki Igarashi

研究成果: ジャーナルへの寄稿学術誌査読

93 被引用数 (Scopus)


The bioactive molecule sphingosine 1-phosphate (S1P) is abundantly stored in platelets and can be released extracellularly. However, although they have high sphingosine (Sph) kinase activity, platelets lack the de novo sphingolipid biosynthesis necessary to provide the substrates. Here, we reveal a generation pathway for Sph, the precursor of S1P, in human platelets. Platelets incorporated extracellular 3H-labeled Sph much faster than human megakaryoblastic cells and rapidly converted it to S1P. Furthermore, Sph formed from plasma sphingomyelin (SM) by bacterial sphingomyelinase (SMase) and neutral ceramidase (CDase) was rapidly incorporated into platelets and converted to S1P, suggesting that platelets use extracellular Sph as a source of S1P. Platelets abundantly express SM, possibly supplied from plasma lipoproteine, at the cell surface. Treating platelets with bacterial SMase resulted in Sph generation at the cell surface, conceivably by the action of membrane-bound neutral CDase. Simultaneously, a time-dependent increase in S1P levels was observed. Finally, we demonstrated that secretory acid SMase also induces S1P increases in platelets. In conclusion, our results suggest that in platelets, Sph is supplied from at least two sources: generation in the plasma followed by incorporation, and generation at the outer leaflet of the plasma membrane, initiated by cell surface SM degradation.

ジャーナルJournal of Lipid Research
出版ステータス出版済み - 11月 2005

!!!All Science Journal Classification (ASJC) codes

  • 生化学
  • 内分泌学
  • 細胞生物学


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