Lyso-Sulfatide Binds Factor Xa and Inhibits Thrombin Generation by the Prothrombinase Complex.
Blood coagulation reactions are strongly influenced by phospholipids, but little is known about the influence of sphingolipids on coagulation mechanisms. Lysosulfatide (lyso-SF) (sulfogalactosyl sphingosine) prolonged factor Xa (fXa) 1-stage plasma clotting assays, showing it had robust anticoagulant activity. In studies using purified clotting factors, lyso-SF inhibited >90% of prothrombin (II) activation for reaction mixtures containing fXa/factor Va (fVa)/II, and also inhibited II activation generation by fXa/ phospholipids and by Gla-domainless-fXa/fVa/phospholipids. When lyso-SF analogs were tested, results showed that N-acetyl-sulfatide was not anticoagulant, implying that the free amine group was essential for the anticoagulant effects of lyso-SF. Lyso-SF did not inhibit fXa enzymatic hydrolysis of small peptide substrates, showing it did not directly inhibit the fXa activity. In surface plasmon resonance studies, lyso-SF bound to immobilized inactivated fXa as well as inactivated Gla-domainless-fXa. Confirming this lyso-SF:fXa interaction, fluorescence studies showed that fluorescently-labeled-fXa in solution bound to lyso-SF. Thus, lyso-SF is an anticoagulant lipid that inhibits fXa when this enzyme is bound to either phospholipids or to fVa. Mechanisms for inhibition of procoagulant activity are likely to involve lyso-SF binding to fXa domain(s) that are distinct from the fXa Gla domain. This suggests that certain sphingolipids, including lyso-SF and some of its analogs, may down-regulate fXa activity without inhibiting the enzyme's active site or binding to the fXa Gla domain.
Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, United States of America.
Subramanian
S
Yegneswaran
Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, United States of America.
Yajnavalka
Y
Banerjee
Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, United States of America.
José A
JA
Fernández
Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, United States of America.
Hiroshi
H
Deguchi
Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California, United States of America.
John H
JH
Griffin
D001777:Blood Coagulation / Q000187:drug effects; D005165:Factor V / Q000378:metabolism*; D015943:Factor Va / Q000378:metabolism; D015951:Factor Xa / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D046912:Multiprotein Complexes / Q000378:metabolism; D010743:Phospholipids / Q000378:metabolism; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D011516:Prothrombin / Q000037:antagonists & inhibitors; D011609:Psychosine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D013917:Thrombin / Q000037:antagonists & inhibitors / Q000096:biosynthesis*
D046912:Multiprotein Complexes; D010743:Phospholipids; C022475:prothrombinase complex; D011609:Psychosine; D015943:Factor Va; C019064:psychosine-3'-sulfate ester; D005165:Factor V; D011516:Prothrombin; D013917:Thrombin; D015951:Factor Xa