Platelet Factor XIII Becomes Active without the Release of Activation Peptide during Platelet Activation

1993 ◽  
Vol 69 (03) ◽  
pp. 282-285 ◽  
Author(s):  
László Muszbek ◽  
János Polgár ◽  
Zoltán Boda
Keyword(s):  
Platelet Activation ◽  
Factor Xiii ◽  
Platelet Factor ◽  
Subunit A ◽  
Cellular Factor ◽  
B Subunit ◽  
Exact Function ◽  
Plasma Factor ◽  
A Subunit ◽  
Activation Peptide

SummaryThe potentially active A subunit of factor XIII of blood coagulation has also been detected in platelets and monocytes/macrophages though the exact function of this cellular protransglutaminase has not yet been elucidated. In physiological conditions the first step in the activation of plasma factor XIII is the removal of an activation peptide from the N-terminal end of subunit A by thrombin. The A subunit then, in the presence of Ca2+, dissociates from the inhibitory B subunit and assumes an active conformation. Cellular factor XIII, which lacks B subunit, can be proteolytically activated in vitro by thrombin and the intracellular Ca2+ sensitive protease, calpain, in the same way as plasma factor XIII subunit A, and calpain has been suggested as the intracellular protease involved in the activation of cellular factor XIII in platelets. In the present experiments it was shown by SDS PAGE that during long-term stimulation of platelets with thrombin nondisulfide-crosslinked high M r protein polymers not penetrating the concentrating gel were formed. The lack of these polymers in thrombin-stimulated factor XIII deficient platelets clearly indicated that their formation in normal platelets was due to factor XIII that became active during platelet activation. However, no release of the activation peptide could be detected by Western blotting during this process. Similarly, no proteolytic cleavage of factor XIII was detectable when platelets were stimulated by Ca2+ ionophore through this stimulus activated calpain as it was clearly demonstrated by the breakdown of major intracellular calpain substrates. The results indicate: 1) during thrombin induced platelet activation factor XIII becomes active and crosslinks platelet protein, 2) platelet factor XIII is not an intracellular substrate of calpain, 3) cellular factor XIII could be activated without the proteolytic removal of activation peptide. It is presumed that the nonproteolytic pathway for the activation of cellular factor XIII, we reported most recently, might have physiological implications under such conditions.

Interactions of Factor XIII Subunits as Studied by Affinity Chromatography

1975 ◽  
Author(s):  
Jan McDonagh ◽  
Richard P. McDonagh
Keyword(s):  
Ionic Strength ◽  
Affinity Chromatography ◽  
Factor Xiii ◽  
National Institutes Of Health ◽  
Platelet Factor ◽  
B Subunit ◽  
Plasma Factor ◽  
A Subunit ◽  
Low Ionic Strength ◽  
Native Plasma

A new method for studying the interactions of plasma factor XIII subunits, as well as purifying both plasma and platelet factor XIII, has been developed using an organomer-curial linked to agarose. Native plasma factor XIII a subunit binds to the ligand accompanied by b subunit, which can be dissociated from the ligated a subunit by treatment with thrombin and calcium. With various combinations of thrombin, calcium, and alteration of ionic strength it has been shown that: (a) both unactivated a subunit and thrombin activated a’ subunit bind to the ligand; (b) “excess” b subunit present in highly purified preparations of plasma factor XIII dissociates and can be eluted at low ionic strength in the absence of calcium or thrombin; (c) in our preparations of highly purified plasma factor XIII approximately 40% of b subunit is in “excess”; (d) the remaining b subunit can be eluted with thrombin and calcium; (e) both a and a’ subunits can be eluted with dithiothreitol ; (f ) when plasma factor XIII zymogen is applied to the column approximately equal amounts of a and b subunits co-elute with dithiothreitol. These observations offer further evidence for the roles of thrombin and calcium in the activation of plasma factor XIII and provide a new tool for studying the structure-function relationships of factor XIII.Supported by Grants HL 14228 and HL 06350 from the National Institutes of Health, U.S.A.

Platelet Calmodulin Mediates The Calcium Dependent Activation Of Factor XIII

1981 ◽  
Author(s):  
D Kahn ◽  
N Crawford ◽  
I Cohen
Keyword(s):  
Factor Xiii ◽  
Sulfhydryl Group ◽  
Cross Linking ◽  
Platelet Factor ◽  
Subunit A ◽  
Calcium Dependent ◽  
B Subunit ◽  
A Subunit ◽  
Subunit B

Transglutaminases are ubiquitous in cells and require calcium for their activation. The factor XIII zymogen, present in plasma and in the platelet cytosol, requires for its activation both a limited proteolytic activity on the catalytic subunit,“a”, and, in the use of the plasma enzyme, calcium for dissociating subunit“a” from the carrier subunit“b”. Calcium is also necessary for exposing the reactive sulfhydryl group. We have recently suggested a role for the platelet factor XIII in the generation of calcium-dependent cross-linking processes in platelets. Since calmodulin is present in considerable amounts in the platelet cytosol and is known to regulate the activity of various calcium-dependent enzymes and cellular reactions, we have investigated its possible role in factor XIII activation. Since the“a” subunit of platelet factor XIII is identical to its plasma counterpart, the more easily purified plasma zymogen was used. The effect of calmodulin on the two calcium-dependent steps of factor XIII activation was investigated following thrombin-stimulated hydrolysis of the“a” subunit. Platelet calmodulin was found to enhance by at least 3 fold the calcium-dependent unmasking of the reactive sulfhydryl groups which were titrated with 14C-iodoacetamide. Calmodulin also enhanced by at least 4 fold the calcium-dependent dissociation of the b subunit from its complex with the thrombin-hydrolyzed“a” subunit. The calmodulin mediation of the calcium-dependent steps of factor XIII activation may be important for regulating the factor XIII-dependent cross-linking reactions in platelets and is reminiscent of the calcium-related regulatory role of fibrinogen on factor XIII activation which could prevail in plasma. An investigation of the possible role of calmodulin on other tissue transglutaminases is warranted.

The Effect Of Plasmin On Factor XIII (Fibrin Stabilizing Factor)

1981 ◽  
Author(s):  
D M Rider ◽  
J M McDonagh
Keyword(s):  
Factor Xiii ◽  
Activate Factor ◽  
Polyacrylamide Gels ◽  
Clotting Factors ◽  
Human Fibrinogen ◽  
Platelet Factor ◽  
Plasma Factor ◽  
Before And After ◽  
A Subunit ◽  
Almost All

The action of plasmin on several blood clotting factors has been studied; however, controversy exists concerning the effect of plasmin on factor XIII. Factor XIII was purified from plasma and platelets and then exposed to plasmin for up to 6 hours. Plasmin to factor XIII ratios ranged from 0.03-0.1 casein units plasmin per mg factor XIII. These plasmin levels exhibited strong proteolytic activities against B-casein and purified human fibrinogen Following incubation of factor XIII (activated and unactivated) with plasmin the mixtures were electrophoresed on 7% SDS-polyacrylamide gels. The factor XIII preparations were assayed for 14C-putrescine incorporating activity before and after exposure to plasmin. Platelet factor XIII was,labeled With 125Iodine and lableled a subunit (activated and unactivated) was exposed to plalmin for up to 2 hours. These mixtures were electrophoresed on 12.5% Urea-SDS Polyacrylamide gels and a radioactivity profile was determined for each gel.Following extensive exposure to Plasmin the relative molecular weights of the factor XIII subunits (a, a* and b)remained constant and almost all (90-100%) of the 14C-put-rescine incorporating activity was recovered. The radio-activity profiles of the gels of 125I-labeled platelet factor XIII were identical before and after incubation with plasmin. Plasmin did not activate factor XIII in the assay system nor did factor XIII inactivate plasmin by crosslinking it. These experiments indicate that plasmin does not activate or degrade factor XIII and that the b subunit of plasma factor XIII plays no role in protecting the a subunit from the action of plasmin.

PLASMA FACTOR XIII AND ACTIVATION PROCESS ANALYZED BY ELISA METHOD FOR A2B2 COMPLEX.

1987 ◽  
Author(s):  
K Koike ◽  
M Hada ◽  
H Yorifuji ◽  
S Ikematsu ◽  
K Fukutake ◽  
...  
Keyword(s):  
Calcium Ion ◽  
Factor Xiii ◽  
Molecular Conformation ◽  
Fibrin Clot ◽  
Activation Process ◽  
Measurement Sensitivity ◽  
B Subunit ◽  
Plasma Factor ◽  
A Subunit ◽  
Subunit B

Factor XIII induces the crosslinking of fibrin at terminal stage of blood coagulation. New ELISA methods of a-subunit, b-subunit and a2b2 complex of factor XIII were developed by the author and the following results concerning the activation process of factor XIII were obtained. New ELISA methods for a-subunit, b-subunit and a2b2 complex of factor XIII were specific with high sensitivities on each items and indicated the measurement capacity for simultaneous quantitation of many samples, more over we looked upon the dissociation of a2b2 complex with these methods to able to analyze at the subunit levels of factor XIII in details. When a-subunit dimer of platelets was discharged into the plasma by the use of freezing and thawing method on PRP, it was more easily affected to lose their antigeniety than that of a2b2 complex, a-subunit levels in the plasma of congenital factor XIII deficiencies were measured in very low concentration or below the measurement sensitivity of this ELISA, b-subunit levels in the same plasma were indicated around the half of normal levels. These results were as same as another immunological method. It was suggested that the molecular conformation of a-subunit could be changed by the addition of thrombin in high concentration and consequently a-subunit with thrombin was modifyed to show high antigeniety. It was observed that a2b2 complex was dissociated by the addition of thrombin without calcium ion, and the process of this dissociation of a2b2 complex was remarkably accelerated by the addition of calcium ion. Because a-subunit and b-subunit were adsorved on fibrin clot, it might be presumed that the crosslinking of fibrin molecules could be accelerated locally on the surface of fibrin clot.

On the Plasmin Digestion of Factor XIII

1975 ◽  
Author(s):  
K. Mikami ◽  
T. Mikami ◽  
H. Suzuki ◽  
M. Fujimaki ◽  
K. Fukutake
Keyword(s):  
Plasma Protein ◽  
Gel Electrophoresis ◽  
Factor Xiii ◽  
Polyacrylamide Gel Electrophoresis ◽  
Polyacrylamide Gel ◽  
Platelet Factor ◽  
Subunit A ◽  
Plasma Factor ◽  
Congenital Afibrinogenemia

The plasmin digestion of factor XIII in the plasma with congenital afibrinogenemia has been reported by Suzuki et al. in 1967. The present investigation using polyacrylamide gel electrophoresis and crossimmunoelectrophoresis with anti-factor XIII (A & S) serum demonstrates that the process of plasmin digestion of factor XIII can be divided into three steps ; the subunit A of factor XIII such as placental or platelet factor XIII is ready to get plasmin digestion following the decrease of amount and activity of subunit A, and the subunit S in the A1 S complex like plasma factor XIII is more readily affectable on the plasmin digestion than the subunit A of the complex, and the A2 S complex coexisting with fibrinogen or plasma protein is fairly stable on exposure to plasmin.

Electroimmunoassay of Plasma Subunits-A and -S in a Case of Congenital Fibrin Stabilizing Factor Deficiency

1974 ◽  
Vol 32 (01) ◽  
pp. 124-131 ◽  
Author(s):  
T Barbui ◽  
G Cartei ◽  
T Chisesi ◽  
E Dini
Keyword(s):  
Factor Xiii ◽  
Binding Protein ◽  
Active Protein ◽  
Abnormal Behaviour ◽  
Subunit A ◽  
Congenital Deficiency ◽  
Factor Deficiency ◽  
Plasma Factor ◽  
Antigenic Material ◽  
A Subunit

SummaryAntigenic material related to the fibrin stabilizing factor (Factor XIII-FSF) has been found in all the examined patients with congenital deficiency, albeit in reduced amount.Recently, Bohn et al. (1973) and Israels et al. (1973) showed that plasma Factor- XIII is composed by two subunits, A (or a) and S (or b); the former active protein, the latter probably FSF-binding protein.Using specific anti-S and anti-A antisera the Authors found, in a case of congenital deficiency of factor XIII, absence of subunit A. Subunit S presented abnormal behaviour as demonstrated by means of quantitative immunoelectrophoresis according to Laurell.

Detection And Regulation Of The Subunit Proteins Of Plasma Factor XIII

1981 ◽  
Author(s):  
J McDonagh ◽  
C Skrzynia ◽  
S Ikematsu
Keyword(s):  
Factor Xiii ◽  
Protein A ◽  
Carrier Protein ◽  
Variable Amount ◽  
Factor Xiii Deficiency ◽  
B Subunit ◽  
Catalytic Function ◽  
Normal Plasma ◽  
Plasma Factor ◽  
A Subunit

Plasma factor XIII circulates as a noncovalently-associated, tetrameric zymogen (a2b2). The a subunit has the potential catalytic function, while the b subunit may act as a carrier protein plasma. In order to study the interactions between the two subunits, specific radioimmunoassays have been developed for each subunit. The assays are valid for measuring a and b protein concentrations in plasma and serum as well as in purified systems. The a assay detects all forms of the protein (zymogen, intermediate, enzyme). Factor XIII activity was measured by the monodansylcadaverine assay. These methods were used to correlate a and b protein concentrations with factor XIII activity in normal donors, in patients with factor XIII deficiency and their family members, and in patients with factor XIII inhibitors.The normal plasma concentration of each of the subunits of factor XIII is about 12 μg/ml, making the concentration of the zymogen complex to be 0.15 μM. All of the b protein is recovered in serum, while a variable amount of a protein (a*) is found in serum. a protein and factor XIII activity go in parallel in normal, factor XIII deficient, and heterozygous plasma samples. Deficient patients have <1% activity and <20 ng/ml a protein. Deficient patients have about 50% of the normal plasma b concentration, and heterozygotes have 50% a and 75% b protein. In three cases of spontaneous, autoimmune inhibitors against factor XIII, there was no detectable activity and b concentration was one-half normal. Following transfusion of two factor XIII deficient patients with a subunit, activity rose immediately to the expected levels, while b rose more slowly to 20% above the preinfusion level. All of these studies indicate that the circulating level of functional a subunit exerts a positive feedback effect on the concentration of b subunit in plasma.

Administration of factor XIII B subunit increased plasma factor XIII A subunit levels in factor XIII B subunit knock-out mice

2007 ◽  
Vol 87 (1) ◽  
pp. 60-68 ◽  
Author(s):  
Masayoshi Souri ◽  
Shiori Koseki-Kuno ◽  
Naoki Takeda ◽  
Jay L. Degen ◽  
Akitada Ichinose
Keyword(s):  
Factor Xiii ◽  
Knock Out ◽  
B Subunit ◽  
Plasma Factor ◽  
A Subunit ◽  
Knock Out Mice

Plasma Factor XIII and Platelet Factor XIII in Hyperlipaemia

1976 ◽  
Vol 36 (03) ◽  
pp. 542-550 ◽  
Author(s):  
Mircea P. Cucuianu ◽  
K Miloszewski ◽  
D Porutiu ◽  
M. S Losowsky
Keyword(s):  
Factor Xiii ◽  
Significant Contribution ◽  
Quantitative Assay ◽  
Factor Xii ◽  
Platelet Factor ◽  
Type Iv ◽  
Plasma Factor ◽  
Hepatic Synthesis

SummaryPlasma factor XIII activity measured by a quantitative assay was found to be significantly higher in hypertriglyceridaemic patients (type IV and combined hyperlipoproteinaemia), as compared to normolipaemic controls. No such elevation in plasma factor XIII activity was found in patients with type IIa hyperlipaemia. Plasma pseudocholinesterase was found to parallel the elevated factor XIII activity in hypertriglyceridaemic subjects.In contrast, platelet factor XIII activity was not raised in hyperlipaemic subjects, and plasma factor XIII was found to be normal in a normolipaemic subject with throm-bocythaemia.It was concluded that there is no significant contribution from platelets to plasma factor XIII activity, and that the observed increase in plasma factor XII in hypertriglyceridaemia results from enhanced hepatic synthesis of the enzyme.

scholarly journals Fibronectin modulates formation of PF4/heparin complexes and is a potential factor for reducing risk of developing HIT

Blood ◽  
2019 ◽  
Vol 133 (9) ◽  
pp. 978-989 ◽  
Author(s):  
Krystin Krauel ◽  
Patricia Preuße ◽  
Theodore E. Warkentin ◽  
Catja Trabhardt ◽  
Sven Brandt ◽  
...  
Keyword(s):  
Platelet Activation ◽  
Platelet Rich Plasma ◽  
Enzyme Linked Immunosorbent Assay ◽  
Heparin Binding ◽  
Plasma Fibronectin ◽  
Platelet Factor ◽  
Washed Platelet ◽  
Plasma Factor ◽  
Heparin Complexes ◽  
Patient Groups

Abstract Heparin-induced thrombocytopenia (HIT) is caused by platelet-activating anti–platelet factor 4 (PF4)/heparin antibodies. Platelet activation assays that use “washed” platelets are more sensitive for detecting HIT antibodies than platelet-rich plasma (PRP)–based assays. Moreover, heparin-exposed patients vary considerably with respect to the risk of PF4/heparin immunization and, among antibody-positive patients, the risk of subsequent “breakthrough” of clinical HIT with manifestation of thrombocytopenia. We used washed platelets and PRP, standard laboratory HIT tests, and physicochemical methods to identify a plasma factor interfering with PF4/heparin complexes and anti-PF4/heparin antibody–platelet interaction, thus explaining differences in functional assays. To investigate a modulating risk for PF4/heparin immunization and breakthrough of HIT, we also tested 89 plasmas from 2 serosurveillance trials. Fibronectin levels were measured in 4 patient groups exhibiting different degrees of heparin-dependent immunization and expression of HIT. The heat-labile plasma protein, fibronectin, inhibited PF4 binding to platelets in a dose-dependent fashion, particularly in washed (vs PRP) systems. Fibronectin also inhibited PF4/heparin binding to platelets, anti-PF4/heparin antibody binding to PF4/heparin complexes, and anti-PF4/heparin antibody–induced platelet activation as a result of PF4/heparin complex disruption. In addition, plasma fibronectin levels increased progressively among the following 4 patient groups: enzyme-linked immunosorbent assay (ELISA)+/serotonin-release assay (SRA)+/HIT+ &lt; ELISA+/SRA+/HIT− ∼ ELISA+/SRA−/HIT− &lt; ELISA−/SRA−/HIT−. Altogether, these findings suggest that fibronectin interferes with PF4/heparin complex formation and anti-PF4/heparin antibody–induced platelet activation. Reduced fibronectin levels in washed platelet assays help to explain the greater sensitivity of washed platelet (vs PRP) assays for HIT. More importantly, lower plasma fibronectin levels could represent a risk factor for PF4/heparin immunization and clinical breakthrough of HIT.

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