1
|
Ceznerová E, Kaufmanová J, Stikarová J, Pastva O, Loužil J, Chrastinová L, Suttnar J, Kotlín R, Dyr JE. Thrombosis-associated hypofibrinogenemia: novel abnormal fibrinogen variant FGG c.8G>A with oxidative posttranslational modifications. Blood Coagul Fibrinolysis 2022; 33:228-237. [PMID: 35067535 DOI: 10.1097/mbc.0000000000001125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Here, we present the first case of fibrinogen variant FGG c.8G>A. We investigated the behaviour of this mutated fibrinogen in blood coagulation using fibrin polymerization, fibrinolysis, fibrinopeptides release measurement, mass spectrometry (MS), and scanning electron microscopy (SEM). The case was identified by routine coagulation testing of a 34-year-old man diagnosed with thrombosis. Initial genetic analysis revealed a heterozygous mutation in exon 1 of the FGG gene encoding gamma chain signal peptide. Fibrin polymerization by thrombin and reptilase showed the normal formation of the fibrin clot. However, maximal absorbance within polymerization was lower and fibrinolysis had a longer degradation phase than healthy control. SEM revealed a significant difference in clot structure of the patient, and interestingly, MS detected several posttranslational oxidations of fibrinogen. The data suggest that the mutation FGG c.8G>A with the combination of the effect of posttranslational modifications causes a novel case of hypofibrinogenemia associated with thrombosis.
Collapse
Affiliation(s)
- Eliška Ceznerová
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, Prague 6, Czech Republic
| | - Jiřina Kaufmanová
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, Prague 6, Czech Republic
| | - Jana Stikarová
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
| | - Ondřej Pastva
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
| | - Jan Loužil
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
| | - Leona Chrastinová
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
| | - Jiři Suttnar
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
| | - Roman Kotlín
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
| | - Jan Evangelista Dyr
- Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 2094/1, Prague 2, Czech Republic
| |
Collapse
|
2
|
Hypofibrinogenemia with preserved hemostasis and protection from thrombosis in mice with an Fga truncation mutation. Blood 2022; 139:1374-1388. [PMID: 34905618 PMCID: PMC8900273 DOI: 10.1182/blood.2021012537] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 11/29/2021] [Indexed: 11/20/2022] Open
Abstract
Genetic variants within the fibrinogen Aα chain encoding the αC-region commonly result in hypodysfibrinogenemia in patients. However, the (patho)physiological consequences and underlying mechanisms of such mutations remain undefined. Here, we generated Fga270 mice carrying a premature termination codon within the Fga gene at residue 271. The Fga270 mutation was compatible with Mendelian inheritance for offspring of heterozygous crosses. Adult Fga270/270 mice were hypofibrinogenemic with ∼10% plasma fibrinogen levels relative to FgaWT/WT mice, linked to 90% reduction in hepatic Fga messenger RNA (mRNA) because of nonsense-mediated decay of the mutant mRNA. Fga270/270 mice had preserved hemostatic potential in vitro and in vivo in models of tail bleeding and laser-induced saphenous vein injury, whereas Fga-/- mice had continuous bleeding. Platelets from FgaWT/WT and Fga270/270 mice displayed comparable initial aggregation following adenosine 5'-diphosphate stimulation, but Fga270/270 platelets quickly disaggregated. Despite ∼10% plasma fibrinogen, the fibrinogen level in Fga270/270 platelets was ∼30% of FgaWT/WT platelets with a compensatory increase in fibronectin. Notably, Fga270/270 mice showed complete protection from thrombosis in the inferior vena cava stasis model. In a model of Staphylococcus aureus peritonitis, Fga270/270 mice supported local, fibrinogen-mediated bacterial clearance and host survival comparable to FgaWT/WT, unlike Fga-/- mice. Decreasing the normal fibrinogen levels to ∼10% with small interfering RNA in mice also provided significant protection from venous thrombosis without compromising hemostatic potential and antimicrobial function. These findings both reveal novel molecular mechanisms underpinning fibrinogen αC-region truncation mutations and highlight the concept that selective fibrinogen reduction may be efficacious for limiting thrombosis while preserving hemostatic and immune protective functions.
Collapse
|
3
|
Yoda M, Kaido T, Kamijo T, Taira C, Higuchi Y, Arai S, Okumura N. Novel variant fibrinogen γp.C352R produced hypodysfibrinogenemia leading to a bleeding episode and failure of infertility treatment. Int J Hematol 2021; 114:325-333. [PMID: 34117991 DOI: 10.1007/s12185-021-03174-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 06/08/2021] [Accepted: 06/09/2021] [Indexed: 12/17/2022]
Abstract
INTRODUCTION We identified a patient with a novel heterozygous variant fibrinogen, γp.C352R (Niigata II; N-II), who had a bleeding episode and failed infertility treatment and was suspected to have hypodysfibrinogenemia based on low and discordant fibrinogen levels (functional assay 0.33 g/L, immunological assay 0.91 g/L). We analyzed the mechanism of this rare phenotype of a congenital fibrinogen disorder. MATERIALS AND METHODS Patient plasma fibrinogen was purified and protein characterization and thrombin-catalyzed fibrin polymerization performed. Recombinant fibrinogen-producing Chinese hamster ovary (CHO) cells were established and the assembly and secretion of variant fibrinogen analyzed by ELISA and western blotting. RESULTS Purified N-II plasma fibrinogen had a small lower molecular weight band below the normal γ-chain and slightly reduced fibrin polymerization. A limited proportion of p.C352R fibrinogen was secreted into the culture medium of established CHO cell lines, but the γ-chain of p.C352R was synthesized and variant fibrinogen was assembled inside the cells. CONCLUSION We demonstrated that fibrinogen N-II, γp.C352R was associated with markedly reduced secretion of variant fibrinogen from CHO cells, that fibrin polymerization of purified plasma fibrinogen was only slightly affected, and that fibrinogen N-II produces hypodysfibrinogenemia in plasma.
Collapse
Affiliation(s)
- Masahiro Yoda
- Department of Clinical Laboratory Investigation, Graduate School of Medicine, Shinshu University, 3-1-1 Asahi, Matsumoto, 390-8621, Japan
| | - Takahiro Kaido
- Department of Clinical Laboratory Investigation, Graduate School of Medicine, Shinshu University, 3-1-1 Asahi, Matsumoto, 390-8621, Japan
| | - Tomu Kamijo
- Department of Medical Sciences, Graduate School of Medicine, Science and Technology, Shinshu University, Matsumoto, Japan
- Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan
| | - Chiaki Taira
- Department of Clinical Laboratory Investigation, Graduate School of Medicine, Shinshu University, 3-1-1 Asahi, Matsumoto, 390-8621, Japan
| | - Yumiko Higuchi
- Department of Clinical Laboratory Investigation, Graduate School of Medicine, Shinshu University, 3-1-1 Asahi, Matsumoto, 390-8621, Japan
| | - Shinpei Arai
- Department of Clinical Laboratory Investigation, Graduate School of Medicine, Shinshu University, 3-1-1 Asahi, Matsumoto, 390-8621, Japan.
| | - Nobuo Okumura
- Department of Clinical Laboratory Investigation, Graduate School of Medicine, Shinshu University, 3-1-1 Asahi, Matsumoto, 390-8621, Japan
- Department of Clinical Laboratory Sciences, School of Health Sciences, Shinshu University, Matsumoto, Japan
| |
Collapse
|
4
|
Simurda T, Caccia S, Asselta R, Zolkova J, Stasko J, Skornova I, Snahnicanova Z, Loderer D, Lasabova Z, Kubisz P. Congenital hypofibrinogenemia associated with a novel heterozygous nonsense mutation in the globular C-terminal domain of the γ-chain (p.Glu275Stop). J Thromb Thrombolysis 2021; 50:233-236. [PMID: 31712947 DOI: 10.1007/s11239-019-01991-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Tomas Simurda
- National Centre of Hemostasis and Thrombosis, Department of Hematology and Transfusiology, Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin and University Hospital Martin, Martin, Slovakia.
| | - Sonia Caccia
- Department of Biomedical and Clinical Sciences "L. Sacco", Università degli Studi di Milano, Milan, Italy
| | - Rosanna Asselta
- Department of Biomedical Sciences, Humanitas University, Pieve Emanuele and Humanitas Clinical and Research Center, IRCCS, Rozzano, Milan, Italy
| | - Jana Zolkova
- National Centre of Hemostasis and Thrombosis, Department of Hematology and Transfusiology, Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin and University Hospital Martin, Martin, Slovakia
| | - Jan Stasko
- National Centre of Hemostasis and Thrombosis, Department of Hematology and Transfusiology, Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin and University Hospital Martin, Martin, Slovakia
| | - Ingrid Skornova
- National Centre of Hemostasis and Thrombosis, Department of Hematology and Transfusiology, Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin and University Hospital Martin, Martin, Slovakia
| | - Zuzana Snahnicanova
- Department of Molecular Biology, Biomedical Center Martin, Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin, Martin, Slovakia
| | - Dusan Loderer
- Department of Molecular Biology, Biomedical Center Martin, Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin, Martin, Slovakia
| | - Zora Lasabova
- Department of Molecular Biology, Biomedical Center Martin, Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin, Martin, Slovakia
| | - Peter Kubisz
- National Centre of Hemostasis and Thrombosis, Department of Hematology and Transfusiology, Comenius University in Bratislava, Jessenius Faculty of Medicine in Martin and University Hospital Martin, Martin, Slovakia
| |
Collapse
|
5
|
Congenital fibrinogen disorder with a compound heterozygote possessing two novel FGB mutations, one qualitative and the other quantitative. Thromb Res 2020; 196:152-158. [PMID: 32871307 DOI: 10.1016/j.thromres.2020.08.031] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 07/08/2020] [Accepted: 08/18/2020] [Indexed: 12/17/2022]
Abstract
INTRODUCTION Congenital fibrinogen disorders result from genetic mutations in FGA, FGB, or FGG resulting in quantitative fibrinogen deficiencies (afibrinogenemia or hypofibrinogenemia) or qualitative fibrinogen deficiencies (dysfibrinogenemia). Hypodysfibrinogenemia sharing features with hypo- and dysfibrinogenemia is rare. We performed genetic and functional analyses of a 31-year-old woman with suspected hypodysfibrinogenemia. MATERIALS AND METHODS Functional and antigenic fibrinogen values of patient were 1.05 and 1.24 g/L, respectively. DNA sequence and western blotting analyses for plasma fibrinogen were performed. A minigene incorporating the mutational region was transfected into a Chinese hamster ovary cell line (CHO), and reverse transcription products were analyzed. Assembly and secretion were examined using the recombinant variant fibrinogen. We purified the patient's plasma fibrinogen and analyzed thrombin-catalyzed fibrin polymerization (TCFP). RESULTS AND CONCLUSIONS DNA sequencing revealed compound heterozygous nucleotide mutations with FGB 35 bp c.1245-17_1262 or -16_1263 del and FGB c.510T>A (resulting in Bβp.N170K substitution) on different alleles. We did not detect shortened Bβ-chain peptides in the plasma using western blotting analysis. A minigene incorporating the deletion DNA showed two aberrant mRNA products. The secretion of Bβp.N170K-fibrinogen-CHO was almost same as normal Bβ-fibrinogen-CHO. TCFP of plasma Bβp.N170K fibrinogen was slightly lower than that of normal plasma fibrinogen. Aberrant splicing products derived from the 35 bp deletion caused hypofibrinogenemia due to nonsense-mediated mRNA decay and suggested the presence of only Bβp.N170K fibrinogen in patient's plasma. Bβp.N170K caused dysfibrinogenemia due to a delay in lateral aggregation. These findings demonstrated that these mutations respectively affected the fibrinogen quality and quantity, resulting in hypodysfibrinogenemia.
Collapse
|
6
|
A Novel Mutation in the Fibrinogen Bβ Chain (c.490G>A; End of Exon 3) Causes a Splicing Abnormality and Ultimately Leads to Congenital Hypofibrinogenemia. Int J Mol Sci 2017; 18:ijms18112470. [PMID: 29156616 PMCID: PMC5713436 DOI: 10.3390/ijms18112470] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 11/15/2017] [Accepted: 11/16/2017] [Indexed: 12/26/2022] Open
Abstract
We found a novel heterozygous mutation in the fibrinogen Bβ chain (c.490G>A) of a 3-year-old girl with congenital hypofibrinogenemia. To clarify the complex genetic mechanism, we made a mini-gene including a FGB c.490G>A mutation region, transfected it into a Chinese Hamster Ovary (CHO) cell line, and analyzed reverse transcription (RT) products. The assembly process and secretion were examined using recombinant mutant fibrinogen. Direct sequencing demonstrated that the mutant RT product was 99 bp longer than the wild-type product, and an extra 99 bases were derived from intron 3. In recombinant expression, a mutant Bβ-chain was weakly detected in the transfected CHO cell line, and aberrant fibrinogen was secreted into culture media; however, an aberrant Bβ-chain was not detected in plasma. Since the aberrant Bβ-chain was catabolized faster in cells, the aberrant Bβ-chain in a small amount of secreted fibrinogen may catabolize in the bloodstream. FGB c.490G>A indicated the activation of a cryptic splice site causing the insertion of 99 bp in intron 3. This splicing abnormality led to the production of a Bβ-chain possessing 33 aberrant amino acids, including two Cys residues in the coiled-coil domain. Therefore, a splicing abnormality may cause impaired fibrinogen assembly and secretion.
Collapse
|
7
|
Mukai S, Nagata K, Ikeda M, Arai S, Sugano M, Honda T, Okumura N. Genetic analyses of novel compound heterozygous hypodysfibrinogenemia, Tsukuba I: FGG c.1129+62_65 del AATA and FGG c.1299+4 del A. Thromb Res 2016; 148:111-117. [PMID: 27837696 DOI: 10.1016/j.thromres.2016.11.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2016] [Revised: 10/24/2016] [Accepted: 11/03/2016] [Indexed: 12/01/2022]
Abstract
INTRODUCTION We found a novel hypodysfibrinogenemia designated Tsukuba I caused by compound heterozygous nucleotide deletions with FGG c.1129+62_65 del AATA and FGG c.1299+4 del A on different alleles. The former was deep in intron 8 of FGG (IVS-8 deletion) and the latter in exon 9 of FGG (Ex-9 deletion), which is translated for the γ'-chain, but not the γA-chain. A Western blot analysis of plasma fibrinogen from our patient revealed an aberrant γ-chain that migrated slightly faster than the normal Bβ-chain. MATERIALS AND METHODS To clarify the complex genetic mechanism underlying Tsukuba I's hypodysfibrinogenemia induced by nucleotide deletions in two regions, we generated two minigenes incorporating each deletion region, transfected them into Chinese Hamster Ovary (CHO) cells, and analyzed RT-PCR products. We also established CHO cells producing the recombinant variant fibrinogen, γ'409ΔA (Ex-9 deletion). RESULTS AND CONCLUSIONS Minigene I incorporating the IVS-8 deletion showed two products: a normal splicing product and the unspliced product. Minigene II incorporating the Ex-9 deletion only produced the unspliced product. The established γ'409ΔA-CHO cells secreted variant fibrinogen more effectively than normal fibrinogen. Therefore, the aberrant splicing products derived from the IVS-8 deletion cause hypofibrinogenemia most likely due to nonsense-mediated mRNA decay and the partial production of normal γA- and γ'-chains; moreover, the Ex-9 deletion causes hypodysfibrinogenemia due to the absence of normal γA- and γ'-chain production (hypofibrinogenemia) and augmented aberrant γ'-chain production (dysfibrinogenemia).
Collapse
Affiliation(s)
- Saki Mukai
- Department of Health and Medical Sciences, Graduate School of Medicine, Shinshu University, Matsumoto, Japan; Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan
| | - Kazuhiro Nagata
- Department of Health and Medical Sciences, Graduate School of Medicine, Shinshu University, Matsumoto, Japan; Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan
| | - Minami Ikeda
- Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan
| | - Shinpei Arai
- Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan; Department of Laboratory Medicine, Graduate School of Medicine, Shinshu University, Matsumoto, Japan
| | - Mitsutoshi Sugano
- Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan
| | - Takayuki Honda
- Department of Laboratory Medicine, Graduate School of Medicine, Shinshu University, Matsumoto, Japan
| | - Nobuo Okumura
- Department of Health and Medical Sciences, Graduate School of Medicine, Shinshu University, Matsumoto, Japan.
| |
Collapse
|
8
|
Luan CJ, Shen W, Yu Z, Chen L, Gu Y, Tang LY, Wang ZG, Dai L, Gu MM. Two nonsense mutations cause protein C deficiency by nonsense-mediated mRNA decay. Thromb Res 2015; 135:733-8. [PMID: 25648792 DOI: 10.1016/j.thromres.2015.01.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 12/22/2014] [Accepted: 01/19/2015] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Protein C deficiency is a genetic disorder caused by mutations in the protein C gene (PROC). More than 10% of nonsense and frameshift mutations carrying premature termination codons have been identified in PROC, but the exact molecular mechanisms of these mutations on the pathogenesis of protein C deficiency remain unclear. OBJECTIVE The aim of this study is to investigate whether nonsense-mediated mRNA decay (NMD) can be a mechanism accounting for protein C deficiency. METHODS PROC of genomic DNA was amplified and sequenced. Recombinant plasmids expressing wild-type (wt) and mutant EGFP-protein C (EGFP-PC) cDNA were constructed and transiently transfected into human embryonic kidney cells using lipofectamine. Expression of mRNAs and proteins of EGFP-PC and NMD factor UPF1 were analyzed by qPCR and Western blot. RESULTS DNA sequencing revealed a novel heterozygous nonsense mutation (p.Trp247*) in patient 1 and two compound heterozygous mutations (p.Phe181Val and p.Arg199*) in patient 2. Expression studies showed that cells transfected with the mutant plasmids expressed significantly lower levels of EGFP-PC mRNAs and proteins compared to cells transfected with the wt plasmid. A translation inhibitor cycloheximide and UPF1 small interfering RNA (UPF1 siRNA) significantly increased mRNA or protein expression of EGFP-PC in cells transfected with the mutant plasmids. CONCLUSION Two PROC nonsense mutations (p.Trp247* and p.Arg199*) trigger NMD, resulting in protein C deficiency.
Collapse
Affiliation(s)
- Chun-jie Luan
- Department of Medical Genetics, E-Institutes of Shanghai Universities, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Wei Shen
- Department of Laboratory Medicine, Renji Hospital, affiliated with Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
| | - Zhen Yu
- Department of Medical Genetics, E-Institutes of Shanghai Universities, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Lei Chen
- Department of Medical Genetics, E-Institutes of Shanghai Universities, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Yi Gu
- Department of Laboratory Medicine, Renji Hospital, affiliated with Shanghai Jiao Tong University School of Medicine, Shanghai 200127, China
| | - Lin-yun Tang
- State Key Laboratory of Medical Genomics, Research Centre for Experimental Medicine, Ruijin Hospital, affiliated with Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Zhu-gang Wang
- Department of Medical Genetics, E-Institutes of Shanghai Universities, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China; State Key Laboratory of Medical Genomics, Research Centre for Experimental Medicine, Ruijin Hospital, affiliated with Shanghai Jiao Tong University School of Medicine, Shanghai, 200025, China
| | - Letian Dai
- Centre for Haemostasis and Thrombosis, Haemophilia Reference Centre, St Thomas Hospital, London SE1 7EH, UK
| | - Ming-min Gu
- Department of Medical Genetics, E-Institutes of Shanghai Universities, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China.
| |
Collapse
|
9
|
Asselta R, Platè M, Robusto M, Borhany M, Guella I, Soldà G, Afrasiabi A, Menegatti M, Shamsi T, Peyvandi F, Duga S. Clinical and molecular characterisation of 21 patients affected by quantitative fibrinogen deficiency. Thromb Haemost 2014; 113:567-76. [PMID: 25427968 DOI: 10.1160/th14-07-0629] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 09/30/2014] [Indexed: 12/14/2022]
Abstract
Fibrinogen is a plasma glycoprotein mainly synthesised by hepatocytes and circulating as a 340-kDa hexamer consisting of two sets of three different polypeptide chains (Aα, Bβ, and γ, encoded by the FGA, FGB, and FGG gene, respectively). Congenital afibrinogenaemia and hypofibrinogenaemia are rare bleeding disorders characterised by abnormally low levels of functional and immunoreactive fibrinogen in plasma, associated with haemorrhagic manifestations of variable severity. While afibrinogenaemia is caused by mutations in the homozygous or compound heterozygous state in one of the three fibrinogen genes, hypofibrinogenaemia is generally due to heterozygous mutations, and is usually characterised by a milder phenotype. The mutational spectrum of these quantitative fibrinogen disorders includes large deletions, point mutations causing premature termination codons, and missense mutations often affecting fibrinogen assembly and/or secretion. Here we report the clinical and molecular characterisation of 13 unrelated afibrinogenaemic and eight hypofibrinogenaemic patients, leading to the identification of 17 different mutations (10 hitherto unknown). All the newly-identified missense and splicing mutations werein vitro expressed to verify their pathogenic role. Our data increase the number of mutations causing quantitative fibrinogen deficiencies by about 7 %. The high number of private mutations identified in the analysed probands indicates that the full mutational screening of the three fibrinogen genes is still required for molecular diagnosis.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Stefano Duga
- Prof. Stefano Duga, PhD, Department of Medical Biotechnology and Translational Medicine, University of Milan, Via Viotti 3/5, 20133 Milan, Italy, Tel.: +39 02 50315823, Fax: +39 02 50315864, E-mail:
| |
Collapse
|
10
|
Ikeda M, Kobayashi T, Arai S, Mukai S, Takezawa Y, Terasawa F, Okumura N. Recombinant γT305A fibrinogen indicates severely impaired fibrin polymerization due to the aberrant function of hole 'A' and calcium binding sites. Thromb Res 2014; 134:518-25. [PMID: 24968960 DOI: 10.1016/j.thromres.2014.06.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Revised: 06/02/2014] [Accepted: 06/03/2014] [Indexed: 10/25/2022]
Abstract
INTRODUCTION We examined a 6-month-old girl with inherited fibrinogen abnormality and no history of bleeding or thrombosis. Routine coagulation screening tests showed a markedly low level of plasma fibrinogen determined by functional measurement and also a low level by antigenic measurement (functional/antigenic ratio=0.295), suggesting hypodysfibrinogenemia. MATERIALS AND METHODS DNA sequence analysis was performed, and γT305A fibrinogen was synthesized in Chinese hamster ovary cells based on the results. We then functionally analyzed and compared with that of nearby recombinant γN308K fibrinogen. RESULTS DNA sequence analysis revealed a heterozygous γT305A substitution (mature protein residue number). The γT305A fibrinogen indicated markedly impaired thrombin-catalyzed fibrin polymerization both in the presence or absence of 1mM calcium ion compared with that of γN308K fibrinogen. Protection of plasmin degradation in the presence of calcium ion or Gly-Pro-Arg-Pro peptide (analogue for so-called knob 'A') and factor XIIIa-catalyzed fibrinogen crosslinking demonstrated that the calcium binding sites, hole 'a' and D:D interaction sites were all markedly impaired, whereas γN308Kwas impaired at the latter two sites. Molecular modeling demonstrated that γT305 is localized at a shorter distance than γN308 from the high affinity calcium binding site and hole 'a'. CONCLUSION Our findings suggest that γT305 might be important for construction of the overall structure of the γ module of fibrinogen. Substitution of γT305A leads to both dysfibrinogenemic and hypofibrinogenemic characterization, namely hypodysfibrinogenemia. We have already reported that recombinant γT305A fibrinogen was synthesized normally and secreted slightly, but was significantly reduced.
Collapse
Affiliation(s)
- Minami Ikeda
- Department of Clinical Laboratory Investigation, Graduate School of Medicine, Shinshu University, Matsumoto, Japan
| | - Tamaki Kobayashi
- Department of Clinical Laboratory Investigation, Graduate School of Medicine, Shinshu University, Matsumoto, Japan; Department of Clinical Laboratory, The University of Tokyo Hospital, Tokyo, Japan
| | - Shinpei Arai
- Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan; Department of Laboratory Medicine, Graduate School of Medicine, Shinshu University, Matsumoto, Japan
| | - Saki Mukai
- Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan; Department of Laboratory Medicine, Graduate School of Medicine, Shinshu University, Matsumoto, Japan
| | - Yuka Takezawa
- Department of Laboratory Medicine, Shinshu University Hospital, Matsumoto, Japan; Department of Laboratory Medicine, Graduate School of Medicine, Shinshu University, Matsumoto, Japan
| | - Fumiko Terasawa
- Department of Clinical Laboratory Investigation, Graduate School of Medicine, Shinshu University, Matsumoto, Japan; Department of Health and Medical Sciences, Graduate School of Medicine, Shinshu University, Matsumoto, Japan
| | - Nobuo Okumura
- Department of Clinical Laboratory Investigation, Graduate School of Medicine, Shinshu University, Matsumoto, Japan; Department of Health and Medical Sciences, Graduate School of Medicine, Shinshu University, Matsumoto, Japan.
| |
Collapse
|