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Exploring the Function of Factor XIII Free B Subunit: Interactions with Complement Factors and a Novel Approach to Identify Potential Binding Partners

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Publisher Elsevier
Date 2022 Jul 25
PMID 35873217
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Abstract

Background: The factor XIII (FXIII)-B subunit has a critical function as a carrier protein to stabilize FXIII-A in plasma and supply it to its main substrate, fibrinogen. However, the function of the excess free FXIII-B circulating in plasma is still elusive.

Objectives: In the present study, we explored potential interactions of free FXIII-B with complement factors and searched for novel binding partners.

Methods: We tested for cofactor activity in the degradation of complement C3b and C4b and used ELISA- and surface plasmon resonance-based binding assays to investigate interactions between FXIII-B and complement components. We performed immunoprecipitation and mass spectrometry analysis to identify potential binding partners of free FXIII-B in freshly drawn plasma samples.

Results: FXIII-B did not exhibit cofactor activity in the degradation of C3b and C4b similar to factor H and C4b-binding protein, nor did it bind to complement factors to a relevant extent. Identification of proteins potentially binding to free FXIII-B revealed high interindividual variation. We confirmed α-macroglobulin (α2MG) as a candidate, although direct interactions or functional effects remain to be validated.

Conclusions: Our study reveals that free FXIII-B has no direct role in regulating the complement system, despite a structural similarity to major complement regulators. Further studies are needed to validate α2MG as a binding partner and explore potential functional consequences of this binding.

Citing Articles

Exploring the function of factor XIII free B subunit: Interactions with complement factors and a novel approach to identify potential binding partners.

Li B, Bechtler C, Jenny L, Ricklin D, Schroeder V Res Pract Thromb Haemost. 2022; 6(5):e12766.

PMID: 35873217 PMC: 9301527. DOI: 10.1002/rth2.12766.

References
1.
Rey-Campos J, Rodriguez de Cordoba S . Physical linkage of the human genes coding for complement factor H and coagulation factor XIII B subunit. Genomics. 1990; 7(4):644-6. DOI: 10.1016/0888-7543(90)90213-e. View

2.
Rodriguez de Cordoba S, Rey-Campos J, Dykes D, McAlpine P, Wong P, Rubinstein P . Coagulation factor XIII B subunit is encoded by a gene linked to the regulator of complement activation (RCA) gene cluster in man. Immunogenetics. 1988; 28(6):452-4. DOI: 10.1007/BF00355378. View

3.
Souri M, Kaetsu H, Ichinose A . Sushi domains in the B subunit of factor XIII responsible for oligomer assembly. Biochemistry. 2008; 47(33):8656-64. DOI: 10.1021/bi8006143. View

4.
Ferreira V, Pangburn M, Cortes C . Complement control protein factor H: the good, the bad, and the inadequate. Mol Immunol. 2010; 47(13):2187-97. PMC: 2921957. DOI: 10.1016/j.molimm.2010.05.007. View

5.
Li B, Bechtler C, Jenny L, Ricklin D, Schroeder V . Exploring the function of factor XIII free B subunit: Interactions with complement factors and a novel approach to identify potential binding partners. Res Pract Thromb Haemost. 2022; 6(5):e12766. PMC: 9301527. DOI: 10.1002/rth2.12766. View