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Clinical and laboratory features of congenital factor XIII deficiency.

OBJECTIVE: This is a retrospective analysis of the clinical and laboratory features of 17 cases of factor XIII deficiency that were followed in tertiary care hospitals in Riyadh, Kingdom of Saudi Arabia, over 20 years. Cases were referred to these hospitals from other health care centers in the country. METHODS: We performed a retrospective analysis of 17 cases of factor XIII deficiency comprising 11 males and 6 females, who were seen over a period of 20 years (1978-1998) in Riyadh, Kingdom of Saudi Arabia. Data variables including age, sex, origin, clinical presentation, bleeding time, prothrombin time, partial thromboplastin time, factor XIII screening and assay, hemoglobin, and platelet count were collected and analyzed. The diagnosis of factor XIII deficiency was made by urea clot lysis test alone in one patient and urea clot lysis test in combination with factor XIII quantitative assay in 16 patients. RESULTS: Eleven patients were males and 6 were females. Median age at the time of diagnosis was 9 years (3-29 years). Ten patients (59%) had a family history of excessive bleeding. Presenting symptoms included ecchymosis and recurrent hematomas in 12 patients (71%), bleeding after circumcision in 6 male patients (55%), umbilical stump bleeding in 7 (41%), poor wound healing and keloids in 3 patients (18%), and intracranial bleeding in 3 patients (18%). Other manifestations included cephalohematoma, abortion, abruptio placenta, and intraperitoneal bleeding (one patient each). Laboratory evaluation revealed a normal prothrombin time, partial thromboplastin time, bleeding time and platelet count in all patients. Factor XIII screening test was positive in all 17 patients tested and assay for factors XIII was <0.06 U/ml in 16 patients tested. CONCLUSION: Our data confirms that factor XIII deficiency is a rare bleeding disorder characterized by variable bleeding manifestations but consistent laboratory findings. The occurrence of keloid in our patient group may reflect the poor quality of the clotting, associated with loss of tensile strength of fibrin polymers, caused by factor XIII deficiency and leading to abnormally large scar formation.

Adolescent↗

Val34Leu factor XIII polymorphism in Italian patients with inflammatory bowel disease.

BACKGROUND: Coagulation Factor XIII is implicated in fibrin stabilization and wound healing. Plasma levels of Factor XIII are reduced in inflammatory bowel disease patients; recently, a valine 34 to leucine polymorphism of the Factor XIII-A subunit gene with a defined protective effect against thrombosis and as yet undetermined effect on wound healing has been described. AIM: To evaluate Val34Leu Factor XIII polymorphism distribution and to find possible correlations with clinical features in Italian inflammatory bowel disease patients. STUDY POPULATION: A total of 152 inflammatory bowel disease patients, 90 with ulcerative colitis and 62 with Crohn's disease and 130 healthy volunteers were studied. METHODS: Val34Leu polymorphism was detected by RFLP with BsaH I. Statistical analysis was performed by means of Fisher exact test. RESULTS: In inflammatory bowel disease, 57.2% of patients showed the wild type status, 37.5% were heterozygous and 5.3% were homozygous for the 34Leu allele; the frequency of the mutated allele was 24.0%. In controls, 66.1% of subjects showed the wild type status, 28.5% were heterozygous and 5.4% were homozygous for the 34Leu allele; the frequency of the mutated allele was 19.7%. There was no difference in genotype distribution and prevalence of the mutated allele between inflammatory bowel disease patients and controls. CONCLUSIONS: The present data do not show any differences in Val34Leu Factor XIII polymorphism distribution between inflammatory bowel disease patients and controls. The prothrombotic state described in inflammatory bowel disease patients does not depend on an altered distribution of Val34Leu Factor XIII polymorphism.

Adult↗

Factor XIII deficiency causing mutation, Ser295Arg, in exon 7 of the factor XIIIA gene.

Inherited factor XIII (FXIII) deficiency is an autosomal recessive disorder which results in a serious bleeding diathesis, problems with wound healing and a very high risk of recurrent miscarriage in deficient females. We have analysed the molecular basis of factor XIII deficiency in two patients and their parents, who originate from the North of Pakistan. Four sequence changes were identified: an AGC-->AGG (Ser-->Arg) FXIII deficiency-causing mutation in codon 295; G-->A at position -246 upstream of exon 1; T-->C and C-->T at positions -23 and -24, respectively, in intron 9. Using molecular modelling we predict that the Ser295Arg mutation would prevent the FXIIIA molecule from folding correctly and thus result in an unstable FXIIIA mutant polypeptide. The sequence changes -246G-->A, -23T-->C and -24C-->T are normal polymorphisms. RT-PCR analysis demonstrates that the intronic sequence changes do not appear to affect the accuracy of FXIIIA RNA processing.

Child↗

Protransglutaminase (factor XIII) mediated crosslinking of fibrinogen and fibrin.

Plasma factor XIII (plasma protransglutaminase) circulates as an A2B2 tetramer bound to the gamma' variant chains of fibrinogen "2". During clotting the A subunits of fXIII are cleaved by thrombin to form fXIIIa (transglutaminase) and in the presence of calcium ions, activated A2* subunits dissociate from the B subunits. When purified plasma fXIII or recombinant cellular factor XIII (A2) was incubated with fibrinogen in the presence of calcium ions (> or =50 microM) a non-synerizing gel formed concomitant with formation of gamma dimers, followed by Agamma polymers, and eventually gamma trimers and gamma tetramers. As is the case of fXIIIa, the fXIII-mediated crosslinking rate was enhanced in the presence of thiols. After an initial lag period, fXIII catalyzed fibrinogen crosslinking at approximately 75% of the rate of fXIIIa under typical crosslinking conditions (100 Loewy u/ml, 5 mM CaCl2 & 500 microM DTT). Fibrin was crosslinked about 8 times more rapidly by fXIII than was fibrinogen, and after an initial lag period fXIII crosslinked fibrin at nearly the same rate as fXIIIa. Substituting plasma for purified fXIII as the source for fXIII resulted in robust fibrinogen crosslinking activity. In contrast to the high level of fXIII-mediated crosslinking activity observed with fibrinogen or fibrin as substrates, when transglutamination was measured using cadaverine incorporation into casein, fXIII was 30-fold less active than fXIIIa. Thus, factor XIII displays constitutive enzymatic activity with respect to fibrinogen and fibrin. The results further indicate that uncleaved fXIII in plasma provides a potent source of readily available crosslinking activity in clotting blood. Fibrinogen 2, whose gamma'chains bind fXIII B subunits, was crosslinked 3.5 times more slowly by fXIII than was fibrinogen 1 (lacking gamma' chains), suggesting that complex formation between fibrinogen 2 and plasma fXIII plays a significant role in down-regulating potential plasma fXIII-mediated crosslinking activity. Since fibrin is a considerably better substrate for fXIII than is fibrinogen, the rate at which crosslinking takes place in a fibrinogen-containing plasma environment is much lower than it would be if fibrin were present.

Calcium↗

An equilibrium study of metal ion binding to human plasma coagulation factor XIII.

1. The binding of Ca2+ to plasma coagulation Factor XIII from man and from cow caused a small decrease in the intrinsic fluorescence of the protein with a dissociation constant of 0.1 mM. A similar decrease was observed with the thrombin-activated Factors (Factors XIIa). The decrease in protein fluorescence was also caused by both Ni2+ and Mn2+ but not by Mg2+. 2. 45Ca2+ binding was directly demonstrated by equilibrium dialysis. Ca2+ at 0.2 mM bound to Factor XIII (a2b2) and Factor XIIIa (a'2b2) but not to isolated b2-protein. A tight-binding site for Ca2+ is associated with the a-subunits. 3. The Ca2+ essential for the enzyme activity of Factor XIII from man, pig and cow can be replaced by Ni2+, Cu2+, La3+, Mn2+, Fe3+, Y3+, Co2+, Sr2+ or Tb3+, but not by Mg2+.

Animals↗

Separation of human plasma fibrin stabilizing factor (factor XIII) from fibrinogen by fibrinogen polymer formation.

Human plasma fibrin stabilizing factor (factor XIII) may be separated from fibrinogen through reversible fibrinogen polymer formation at pH 6.6, gamma/2 0.3, 0 degrees C, and subsequent Bio-Gel A 1.5m filtration. Factor XIII activity is eluted after the monomer fibrinogen peak. Polymer fractions from eight preparations, processed in duplicate, contain a mean 0.002 units factor XIII per mg fibrinogen, or about 0.7% the factor XIII content of standard plasma. Factor XIII-free fibrinogen polymers are easily dissociated (greater than 98%) to the monomer form by incubation at 37 degrees C, 18 hours. The fibrinogen preparations utilized were devoid of plasma fibronectin; thus these studies also show that reversible human fibrinogen polymer formation occurs in its absence.

Chromatography, Gel↗

The V34L polymorphism of factor XIII and peripheral arterial disease.

BACKGROUND: Factor XIII catalyzes crosslinking of fibrin in the last steps of the coagulation process. A common polymorphism in the gene for factor XIII A subunit (F13A1 V34L) has been associated with a decreased risk for coronary artery disease, cerebrovascular disease, and deep venous thrombosis. METHODS: To analyze the role of this polymorphism in peripheral arterial disease (PAD) we performed a case-control study including 873 patients with documented PAD and a total of 523 controls without vascular disease. The F13A1 genotype was determined by an allele-specific polymerase chain reaction. RESULTS: Genotype distribution and allele frequencies were not significantly different between patients (VV: 51.9%; VL: 40.7%; LL: 7.4%) and controls (VV: 54.7%; VL: 39.2%; LL: 6.1%). Mean age at onset of the disease was significantly higher in LL homozygous subjects than in VV homozygous subjects (67.3 versus 64.1 years, p=0.017). Heterozygous subjects had an intermediate age at onset (65.1 years), suggesting a gene-dose effect. The association of the L34 variant with onset of PAD remained significant after adjustment for other risk factors. The effect was stronger in men than in women. CONCLUSIONS: We conclude that the F13A1 V34L polymorphism was not associated with the presence of PAD in our study, but may be linked to a later onset of the disease.

Aged↗

A familial factor XIII subunit B deficiency.

A 32-year-old woman with a bleeding tendency born of a consanguineous marriage, was found to have factor XIII subunit B deficiency. An abnormally low level of factor XIII activity was initially noticed and this finding led to further studies of the proband and her family. The notable features were: undetectable subunit B of factor XIII in the proband and her brother and reduced levels of subunit B, 34-52%, in her parents and children. The proband's brother had a markedly decreased level of subunit A protein. The level of factor XIII subunit A in platelets of the proband was normal. The half-life of subunit A determined from the disappearance curve of infused factor XIII subunit A concentrate was approximately 3 d and this is the shortest estimate of the half-life of factor XIII to date. From these results, it is suggested that subunit A is unstable in plasma deficient in subunit B and subunit B stabilizes the A protein. This is the first report of congenital deficiency of factor XIII subunit B and this disorder is thought to be inherited as an autosomal recessive trait.

Adult↗

Factor XIII deficiency: new nonsense and deletion mutations in the human factor XIIIA gene.

We identified five disease-causing mutations in six factor XIII deficient patients from four unrelated families: two novel nonsense mutations (nucleotide 979C-->T corresponding to Arg326Stop; and nucleotide 2075G-->A corresponding to Trp691 Stop), one novel deletion of a single nucleotide (nucleotide 708G or 709G), one previously reported missense mutation (nucleotide 888C-->G corresponding to Ser295Arg), and a previously reported splice site mutation (nucleotide 319G-->T at the last position of exon 3). The phenotypic consequences of these mutations are discussed.

Adolescent↗

The binding of divalent metal ions to platelet factor XIII modulates its proteolysis by trypsin and thrombin.

We investigated the effect of divalent metal ions on the proteolytic cleavage and activation of platelet Factor XIII by thrombin and trypsin. In the absence of metal ions (5 mM EDTA), trypsin and thrombin rapidly degraded platelet Factor XIII (80 kDa) to low-molecular-mass peptides (50-19 kDa) with simultaneous loss of transglutaminase activity. Divalent metal ions protected Factor XIII from proteolytic inactivation with an order of efficacy of Ca2+ greater than Zn2+ greater than Mg2+ greater than Mn2+. Calcium (2 mM) increased by 10- to 1000-fold the trypsin and thrombin concentrations required to degrade Factor XIII to a 19-kDa peptide. Factor XIIIa formed by thrombin in the presence of 5 mM EDTA had one-half the specific activity of Factor XIIIa formed in the presence of calcium. Factor XIII was cleaved by trypsin in the presence of 5 mM Ca2+ to a 51 +/- 3-kDa fragment that had 60% of the original Factor XIIIa activity. A similar tryptic peptide formed in the presence of 5 mM EDTA did not have transglutaminase activity. In the presence of 5 mM Mg2+, thrombin cleaved Factor XIII to a major 51 +/- 3-kDa fragment that had 60% of the Factor XIIIa activity. Mn2+ (0.1-5 mM) limited trypsin and thrombin proteolysis. The resulting digest containing a population of Factor XIII fragments (50-14 kDa) expressed 50-60% transglutaminase activity of Factor XIIIa. Factor XIII was fully activated by both trypsin and thrombin in the presence of 5 mM Zn2+, resulting in two fragments of 76 and 72 kDa. We conclude that the binding of divalent metal ions to platelet Factor XIII induces conformational changes in the protein that alter its susceptibility to proteolysis and influence the expression of transglutaminase activity.

Cations, Divalent↗

Characterization of the kinetic pathway for fibrin promotion of alpha-thrombin-catalyzed activation of plasma factor XIII.

Kinetic and thermodynamic studies are presented showing that the cofactor activity of fibrin I (polymerized des-A fibrinogen) in the alpha-thrombin-catalyzed proteolysis of activation peptide (AP) from plasma factor XIII can be attributed to formation of a fibrin I-plasma factor XIII complex (Kd = 65 nM), which is processed by alpha-thrombin more efficiently (kcat/Km = 1.2 x 10(7) M-1 s-1) than free, uncomplexed plasma factor XIII (kcat/Km = 1.4 x 10(5) M-1 s-1). The increase in the specificity constant (kcat/Km) is shown to be largely due to an increase in the apparent affinity of alpha-thrombin for the complex of plasma factor XIII and fibrin I, as reflected by the 30-fold decrease in the Michaelis constant observed for fibrin I bound plasma factor XIII relative to that for uncomplexed plasma factor XIII. Analysis of the initial rates of alpha-thrombin-catalyzed hydrolysis of fibrinopeptide B (FPB) from fibrin I polymer in the presence of plasma factor XIII indicated that alpha-thrombin bound to fibrin I in the ternary complex of alpha-thrombin, plasma factor XIII, and fibrin I polymer is competent to catalyze cleavage of both FPB from fibrin I and AP from plasma factor XIII. This observation is consistent with the view that alpha-thrombin within the ternary complex is anchored to fibrin I polymer through a binding site distinct from the active site (an exosite) and that the active site is alternatively complexed with the AP moiety of plasma factor XIII or the FPB moiety of fibrin I. This conclusion is supported by the observation that a 12-residue peptide, which binds to an exosite of alpha-thrombin and blocks the interaction of alpha-thrombin with fibrinogen and fibrin, competitively inhibits alpha-thrombin-catalyzed release of both FPB and AP from the fibrin I-plasma factor XIII complex.

Binding, Competitive↗

Structural evidence that the activation peptide is not released upon thrombin cleavage of factor XIII.

The three-dimensional structure of the recombinant human factor XIII a2 dimer after cleavage by thrombin has been determined by X-ray crystallography. Factor XIII zymogen was treated with bovine alpha-thrombin in the presence of 3 mM CaCl2, and the cleaved protein was crystallized from Tris buffered at pH 6.5 using ethanol as the precipitating agent. Refinement of the molecular model of thrombin-cleaved factor XIII against diffraction data from 10.0 to 2.5 A resolution has been carried out to give a crystallographic R factor of 18.2%. The structure of thrombin-cleaved factor XIII is remarkably similar to that of the zymogen: there are no large conformational changes in the protein and the 37 residue amino terminus activation peptide remains associated with the rest of the molecule. This work shows that the activation peptide, upon thrombin cleavage, has the same conformation and occupies the same position with respect to the rest of the molecule as it does in the zymogen structure.

Animals↗

The half life of factor XIII in the management of inherited deficiency.

Following the injection of a large dose of factor XIII concentrate the in vivo half life of factor XIII was estimated in a patient with inherited deficiency. Factor XIII activity and enzyme concentration were measured quantitatively, and a qualitative assessment of the crosslinking of fibrin was also made for upto 6 weeks after the injection. The half life was found to be about 9--10 days. This is longer than most previous reports suggest. An explantation for this finding is offered. The relevance of the long half life of factor XIII to the prophylactic treatment of patients with inherited deficiency is demonstrated.

Factor XIII↗

Evaluating the roles of thrombin and calcium in the activation of coagulation factor XIII using H/D exchange and MALDI-TOF MS.

Factor XIII catalyzes the formation of isopeptide bonds between noncovalently associated fibrin monomers in the final stages of the blood coagulation cascade. This results in a rigid, covalently linked network that is much more resistant to proteolytic degradation. Calcium ion is critical to this process, and its continued presence after activation aids in maintenance of Factor XIII activity. Hydrogen/deuterium exchange experiments were conducted on recombinant Factor XIII a(2) using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. The method revealed changes in the structure of Factor XIII a(2) localized to different areas of the protein that were related to the manner in which the enzyme was activated and the calcium environment in which it was maintained. A possible substrate recognition region in the catalytic core (220-230) shows an increase in deuteration upon activation. The degree of deuteration varies depending on the calcium environment in which the active enzyme is maintained. A portion of the beta-sandwich domain (98-104) exhibits a decrease in deuteration upon activation by exposure to calcium alone. A third change occurs in the beta-barrel 1 domain of the protein, a portion of which (526-546) shows a decrease in deuteration upon activation by calcium exposure, but almost none at all when the enzyme is activated by thrombin. The pattern of observed changes reveals individual contributions of calcium and thrombin to activating the enzyme toward substrate binding and exposure of the active site.

Amino Acid Sequence↗

Platelet factor XIII becomes active without the release of activation peptide during platelet activation.

The potentially active A subunit of factor XIII of blood coagulation has also been detected in platelets and monocytes/macrophages through 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Platelets↗

Affinity chromatography of human plasma and platelet factor XIII on organomercurial agarose.

A method for affinity chromatography of plasma and platelet factor XIII has been developed, based on known structural characteristics of these molecules. Plasma factor XIII is composed of a and b subunits which are held together by noncovalent interactions; platelet factor XIII has only a subunits. a subunit contains free sulfhydryl groups, while in b subunit all the cystines form disulfide bonds. The affinity gel is an organomercurial agarose with p-chloromercuribenzoate as the reactive group. Both the zymogen and activated forms of a subunit reversibly bind to the ligand by forming covalent mercaptide bonds and are eluted by reducing agents. b subunit does not bind to the affinity gel and is held to it only through interaction with a subunit. Affinity chromatography can be used to purify plasma and platelet factor XIII and to study interactions of the subunits. Experiments on the affinity chromatography of purified plasma factor XIII in several stages of activation agree with earlier observations that activation is a two-step procedure in which b subunit is not quantitatively released from the complex until the final stage of activation by Ca2+.

Amino Acids↗

Factor XIII cross-linking of fibronectin at cellular matrix assembly sites.

We describe the effect of activated Factor XIII (Factor XIIIa, plasma transglutaminase) on the incorporation of plasma fibronectin into extracellular matrix by cultured human fibroblasts. In the absence of added Factor XIIIa, fibronectin binds to cultured fibroblast cell layers and is assembled into disulfide-bonded multimers of the extracellular matrix. When Factor XIIIa was included in the binding medium of skin fibroblasts, accumulation of 125I-fibronectin in the deoxycholate-insoluble matrix was increased. Fibronectin accumulating in the cell layer was cross-linked into nonreducible high molecular weight aggregates. The 70-kDa amino-terminal fragment of fibronectin inhibited the binding and cross-linking of 125I-fibronectin to cell layers, whereas fibrinogen had little effect. When 125I-fibronectin was incubated with isolated matrices or with cell layers pretreated with cytochalasin B, it did not bind and could not be cross-linked by Factor XIIIa into the matrix. HT-1080 human fibrosarcoma cells bound exogenous fibronectin following treatment with dexamethasone; Factor XIIIa cross-linked the bound fibronectin and caused its efficient transfer to the deoxycholate-insoluble matrix. These results indicate that exogenous fibronectin is susceptible to Factor XIIIa-catalyzed cross-linking at cellular sites of matrix assembly. Thus, Factor XIIIa-mediated fibronectin cross-linking complements disulfide-bonded multimer formation in the stabilization of assembling fibronectin molecules and thus enhances the formation of extracellular matrix.

Cell Line↗

Factor XIII, fibrin and collagen.

It has been demonstrated that activated factor XIII may catalyze the formation of covalent cross-links between fibrin and collagen. This is shown by the disappearance of the gamma-gamma dimer band in PAA-SDS gel electrophoresis when fibrinogen is clotted in presence of collagen, factor XIII and Ca ions, and by the binding of labeled fibrinogen. This reaction may explain the outstanding physiological importance of factor XIII.

Collagen↗