title: Spatial distribution of factor Xa, thrombin, and fibrin(ogen) on thrombi at venous shear.
abstract: BACKGROUND
  The generation of thrombin is a critical process in the formation of venous thrombi. In isolated plasma under static conditions, phosphatidylserine (PS)-exposing platelets support coagulation factor activation and thrombin generation; however, their role in supporting coagulation factor binding under shear conditions remains unclear. We sought to determine where activated factor X (FXa), (pro)thrombin, and fibrin(ogen) are localized in thrombi formed under venous shear.
  
  
  RESULTS
  Fluorescence microscopy was used to study the accumulation of platelets, FXa, (pro)thrombin, and fibrin(ogen) in thrombi formed in vitro and in vivo. Co-perfusion of human blood with tissue factor resulted in formation of visible fibrin at low, but not at high shear rate. At low shear, platelets demonstrated increased Ca(2+) signaling and PS exposure, and supported binding of FXa and prothrombin. However, once cleaved, (pro)thrombin was observed on fibrin fibers, covering the whole thrombus. In vivo, wild-type mice were injected with fluorescently labeled coagulation factors and venous thrombus formation was monitored in mesenteric veins treated with FeCl(3). Thrombi formed in vivo consisted of platelet aggregates, focal spots of platelets binding FXa, and large areas binding (pro)thrombin and fibrin(ogen).
  
  
  CONCLUSIONS
  FXa bound in a punctate manner to thrombi under shear, while thrombin and fibrin(ogen) distributed ubiquitously over platelet-fibrin thrombi. During thrombus formation under venous shear, thrombin may relocate from focal sites of formation (on FXa-binding platelets) to dispersed sites of action (on fibrin fibers).
authors.affiliation: Department of Biochemistry, CARIM, Maastricht University, Maastricht, The Netherlands.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Berny
authors.forename: Imke C A
authors.initials: IC
authors.lastname: Munnix
authors.forename: Jocelyn M
authors.initials: JM
authors.lastname: Auger
authors.forename: Saskia E M
authors.initials: SE
authors.lastname: Schols
authors.forename: Judith M E M
authors.initials: JM
authors.lastname: Cosemans
authors.forename: Peter
authors.initials: P
authors.lastname: Panizzi
authors.forename: Paul E
authors.initials: PE
authors.lastname: Bock
authors.forename: Steve P
authors.initials: SP
authors.lastname: Watson
authors.forename: Owen J T
authors.initials: OJ
authors.lastname: McCarty
authors.forename: Johan W M
authors.initials: JW
authors.lastname: Heemskerk
mesh_terms: D000818:Animals; D001792:Blood Platelets; D020013:Calcium Signaling; D015951:Factor Xa / Q000032:analysis*; D005337:Fibrin / Q000032:analysis*; D005340:Fibrinogen / Q000032:analysis; D006801:Humans; D051379:Mice; D010477:Perfusion; D010718:Phosphatidylserines; D010974:Platelet Aggregation; D011485:Protein Binding; D013917:Thrombin / Q000032:analysis*; D013925:Thromboplastin; D020246:Venous Thrombosis / Q000473:pathology*
chemical_list: D010718:Phosphatidylserines; D005337:Fibrin; D005340:Fibrinogen; D013925:Thromboplastin; D013917:Thrombin; D015951:Factor Xa
references.citation: J Clin Invest. 2005 Dec;115(12):3355-62
references.pmid: 16322780
references.citation: J Biol Chem. 2008 Feb 1;283(5):2470-7
references.pmid: 18055456
references.citation: J Thromb Haemost. 2007 Jul;5 Suppl 1:12-7
references.pmid: 17635703
references.citation: Microcirculation. 2008 May;15(4):269-82
references.pmid: 18464157
references.citation: Thromb Haemost. 2002 Jul;88(1):26-31
references.pmid: 12152671
references.citation: J Thromb Haemost. 2003 Nov;1(11):2348-55
references.pmid: 14629468
references.citation: Arterioscler Thromb Vasc Biol. 2006 Aug;26(8):1738-45
references.pmid: 16728654
references.citation: J Biol Chem. 2003 Jun 13;278(24):21584-91
references.pmid: 12682049
references.citation: Nat Med. 2009 Jun;15(6):665-73
references.pmid: 19465929
references.citation: Circulation. 1998 Feb 17;97(6):544-52
references.pmid: 9494024
references.citation: J Thromb Haemost. 2003 Jan;1(1):48-59
references.pmid: 12871539
references.citation: FASEB J. 2005 May;19(7):825-7
references.pmid: 15758040
references.citation: Blood. 1980 Feb;55(2):169-78
references.pmid: 6766334
references.citation: Microcirculation. 2008 May;15(4):325-35
references.pmid: 18464161
references.citation: J Clin Invest. 2000 Aug;106(3):385-92
references.pmid: 10930441
references.citation: Blood. 2004 Jan 15;103(2):594-600
references.pmid: 12969982
references.citation: Arteriosclerosis. 1990 Jul-Aug;10(4):607-15
references.pmid: 2369370
references.citation: J Biol Chem. 2008 Oct 31;283(44):30164-73
references.pmid: 18765660
references.citation: Arterioscler Thromb Vasc Biol. 2007 Nov;27(11):2484-90
references.pmid: 17761939
references.citation: J Clin Invest. 1999 Mar;103(6):879-87
references.pmid: 10079109
references.citation: J Thromb Haemost. 2003 Jan;1(1):60-8
references.pmid: 12871540
references.citation: Blood. 2004 Feb 15;103(4):1333-41
references.pmid: 14563646
references.citation: J Biol Chem. 1996 Sep 20;271(38):23121-5
references.pmid: 8798504
references.citation: Clin Chim Acta. 1996 Jul 15;251(1):65-80
references.pmid: 8814351
references.citation: Thromb Haemost. 2001 Aug;86(2):660-7
references.pmid: 11522019
references.citation: J Thromb Haemost. 2005 Aug;3(8):1894-904
references.pmid: 16102057
references.citation: J Biol Chem. 1985 Feb 25;260(4):2119-24
references.pmid: 3972783
references.citation: J Clin Invest. 2007 Apr;117(4):953-60
references.pmid: 17380206
references.citation: Thromb Haemost. 2008 Jun;99(6):1068-78
references.pmid: 18521510
references.citation: J Thromb Haemost. 2004 Mar;2(3):476-84
references.pmid: 15009466
references.citation: Thromb Haemost. 2000 Apr;83(4):589-91
references.pmid: 10780322
references.citation: J Biol Chem. 1972 Aug 25;247(16):5223-7
references.pmid: 5057464
references.citation: Thromb Haemost. 2004 Jun;91(6):1129-36
references.pmid: 15175799
references.citation: J Clin Invest. 1982 Feb;69(2):263-9
references.pmid: 6460044
references.citation: Thromb Haemost. 2002 Aug;88(2):186-93
references.pmid: 12195687
references.citation: Blood. 2003 Nov 15;102(10):3609-14
references.pmid: 12855554
references.citation: Biochemistry. 1995 Sep 12;34(36):11625-34
references.pmid: 7547894
references.citation: J Clin Invest. 1986 Oct;78(4):1072-82
references.pmid: 3760183
references.citation: Thromb Haemost. 1997 Jul;78(1):590-4
references.pmid: 9198221
references.citation: J Biol Chem. 1992 Jul 25;267(21):14974-81
references.pmid: 1634536
references.citation: Arterioscler Thromb Vasc Biol. 2008 Feb;28(2):329-34
references.pmid: 17962622
references.citation: Blood. 1997 Feb 15;89(4):1121-32
references.pmid: 9028933
references.citation: J Biol Chem. 2006 Jan 13;281(2):1169-78
references.pmid: 16230340