Enhanced fibrinolysis by proteolysed coagulation factor Xa

Biochimica Et Biophysica Acta
Kimberley TalbotE L Pryzdial

Abstract

We previously showed that coagulation factor Xa (FXa) enhances activation of the fibrinolysis zymogen plasminogen to plasmin by tissue plasminogen activator (tPA). Implying that proteolytic modulation occurs in situ, intact FXa (FXaalpha) must be sequentially cleaved by plasmin or autoproteolysis, producing FXabeta and Xa33/13, which acquire necessary plasminogen binding sites. The implicit function of Xa33/13 in plasmin generation has not been demonstrated, nor has FXaalpha/beta or Xa33/13 been studied in clot lysis experiments. We now report that purified Xa33/13 increases tPA-dependent plasmin generation by at least 10-fold. Western blots confirmed that in situ conversion of FXaalpha/beta to Xa33/13 correlated to enhanced plasmin generation. Chemical modification of the FXaalpha active site resulted in the proteolytic generation of a product distinct from Xa33/13 and inhibited the enhancement of plasminogen activation. Identical modification of Xa33/13 had no effect on tPA cofactor function. Due to its overwhelming concentration in the clot, fibrin is the accepted tPA cofactor. Nevertheless, at the functional level of tPA that circulates in plasma, FXaalpha/beta or Xa33/13 greatly reduced purified fibrin lysis times by as mu...Continue Reading

References

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Citations

Sep 14, 2011·The Journal of Biological Chemistry·Jennifer L Newell-CaitoPaul E Bock
Feb 19, 2013·Biochimica Et Biophysica Acta·Kimberley TalbotEdward L G Pryzdial
Oct 9, 2012·Journal of Thrombosis and Haemostasis : JTH·A L Vanden HoekE L G Pryzdial
Apr 17, 2015·Mediators of Inflammation·Michael Schuliga
Jul 1, 2016·Journal of Thrombosis and Haemostasis : JTH·E L G PryzdialW P Sheffield
Sep 4, 2018·Journal of Thrombosis and Haemostasis : JTH·R L R CarterE L G Pryzdial
Feb 10, 2012·Thrombosis and Haemostasis·E S GershomE L G Pryzdial
Dec 18, 2013·International Journal of Molecular Medicine·Jerzy JankunBogusław Lipinski

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