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Evidence for factor IX-independent roles for factor XIa in blood coagulation.
J Thromb Haemost. 2013 Dec; 11(12):2118-27.JT

Abstract

BACKGROUND

Factor XIa is traditionally assigned a role in FIX activation during coagulation. However, recent evidence suggests this protease may have additional plasma substrates.

OBJECTIVE

To determine whether FXIa promotes thrombin generation and coagulation in plasma in the absence of FIX, and to determine whether FXI-deficiency produces an antithrombotic effect in mice independently of FIX.

METHODS

FXIa, FXIa variants and anti-FXIa antibodies were tested for their effects on plasma coagulation and thrombin generation in the absence of FIX, and for their effects on the activation of purified coagulation factors. Mice with combined FIX and FXI deficiency were compared with mice lacking either FIX or FXI in an arterial thrombosis model.

RESULTS

In FIX-deficient plasma, FXIa induced thrombin generation, and anti-FXIa antibodies prolonged clotting times. This process involved FXIa-mediated conversion of FX and FV to their active forms. Activation of FV by FXIa required the A3 domain on the FXIa heavy chain, whereas activation of FX did not. FX activation by FXIa, unlike FIX activation, was not a calcium-dependent process. Mice lacking both FIX and FXI were more resistant to ferric chloride-induced carotid artery occlusion than FXI-deficient or FIX-deficient mice.

CONCLUSION

In addition to its predominant role as an activator of FIX, FXIa may contribute to coagulation by activating FX and FV. As the latter reactions do not require calcium, they may make important contributions to in vitro clotting triggered by contact activation. The reactions may be relevant to FXIa's roles in hemostasis and in promoting thrombosis.

Authors+Show Affiliations

Department of Pathology, Microbiology, and Immunology, Vanderbilt University, Nashville, TN, USA; Department of Bioengineering and Organic Chemistry, Tomsk Polytechnic University, Tomsk, Russia.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

24152424

Citation

Matafonov, A, et al. "Evidence for Factor IX-independent Roles for Factor XIa in Blood Coagulation." Journal of Thrombosis and Haemostasis : JTH, vol. 11, no. 12, 2013, pp. 2118-27.
Matafonov A, Cheng Q, Geng Y, et al. Evidence for factor IX-independent roles for factor XIa in blood coagulation. J Thromb Haemost. 2013;11(12):2118-27.
Matafonov, A., Cheng, Q., Geng, Y., Verhamme, I. M., Umunakwe, O., Tucker, E. I., Sun, M. F., Serebrov, V., Gruber, A., & Gailani, D. (2013). Evidence for factor IX-independent roles for factor XIa in blood coagulation. Journal of Thrombosis and Haemostasis : JTH, 11(12), 2118-27. https://doi.org/10.1111/jth.12435
Matafonov A, et al. Evidence for Factor IX-independent Roles for Factor XIa in Blood Coagulation. J Thromb Haemost. 2013;11(12):2118-27. PubMed PMID: 24152424.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Evidence for factor IX-independent roles for factor XIa in blood coagulation. AU - Matafonov,A, AU - Cheng,Q, AU - Geng,Y, AU - Verhamme,I M, AU - Umunakwe,O, AU - Tucker,E I, AU - Sun,M-F, AU - Serebrov,V, AU - Gruber,A, AU - Gailani,D, PY - 2013/06/24/received PY - 2013/10/15/accepted PY - 2013/10/25/entrez PY - 2013/10/25/pubmed PY - 2014/11/15/medline KW - factor IX KW - factor V KW - factor X KW - factor XI KW - factor XIa SP - 2118 EP - 27 JF - Journal of thrombosis and haemostasis : JTH JO - J Thromb Haemost VL - 11 IS - 12 N2 - BACKGROUND: Factor XIa is traditionally assigned a role in FIX activation during coagulation. However, recent evidence suggests this protease may have additional plasma substrates. OBJECTIVE: To determine whether FXIa promotes thrombin generation and coagulation in plasma in the absence of FIX, and to determine whether FXI-deficiency produces an antithrombotic effect in mice independently of FIX. METHODS: FXIa, FXIa variants and anti-FXIa antibodies were tested for their effects on plasma coagulation and thrombin generation in the absence of FIX, and for their effects on the activation of purified coagulation factors. Mice with combined FIX and FXI deficiency were compared with mice lacking either FIX or FXI in an arterial thrombosis model. RESULTS: In FIX-deficient plasma, FXIa induced thrombin generation, and anti-FXIa antibodies prolonged clotting times. This process involved FXIa-mediated conversion of FX and FV to their active forms. Activation of FV by FXIa required the A3 domain on the FXIa heavy chain, whereas activation of FX did not. FX activation by FXIa, unlike FIX activation, was not a calcium-dependent process. Mice lacking both FIX and FXI were more resistant to ferric chloride-induced carotid artery occlusion than FXI-deficient or FIX-deficient mice. CONCLUSION: In addition to its predominant role as an activator of FIX, FXIa may contribute to coagulation by activating FX and FV. As the latter reactions do not require calcium, they may make important contributions to in vitro clotting triggered by contact activation. The reactions may be relevant to FXIa's roles in hemostasis and in promoting thrombosis. SN - 1538-7836 UR - https://www.unboundmedicine.com/medline/citation/24152424/Evidence_for_factor_IX_independent_roles_for_factor_XIa_in_blood_coagulation_ L2 - https://doi.org/10.1111/jth.12435 DB - PRIME DP - Unbound Medicine ER -