siRNA down-regulation of FGA mRNA in HepG2 cells demonstrated that heterozygous abnormality of the A alpha-chain gene does not affect the plasma fibrinogen level

Introduction: We encountered two afibrinogenemia patients with homozygous and compound heterozygous FGA mutation. Of interest, the patients' parents, who are heterozygous, had normal levels of plasma fibrinogen; thus, we hypothesized that liver FGA mRNA levels were higher than those of FGB and/or FGG mRNA. Materials and Methods: To test the hypothesis, we quantitated mRNA levels of a normal liver and a human hepatocyte cell line, HepG2 cells, and performed siRNA-mediated down-regulation of the fibrinogen gene in HepG2 cells. mRNA levels were determined using real-time quantitative RT-PCR for three normal livers and HepG2 cells. Down-regulation of FGA, FGB, or FGG in HepG2 cells was performed by the addition of siRNA corresponding to each of the three genes, and the mRNA levels determined in the cells and the secreted fibrinogen concentration in media. Results: The mRNA level of normal human liver was FGA=FGB>FGG and the FGG mRNA level was about 2-fold lower than the others, that of HepG2 cells was FGA>FGG>FGB and FGA mRNA was approximately 2- or 4-fold higher than FGG mRNA and FGB mRNA. When FGA, FGB, or FGG mRNA expression levels were down-regulated by nearby 50%, fibrinogen concentrations in media were 78%, 49%, or 57% of the control, respectively. Conclusions: Our results suggest that FGG mRNA levels limit fibrinogen expression in normal liver and HepG2 cells and that 50% reduction of FGA mRNA levels would not limit fibrinogen expression in normal liver and HepG2 cells.ArticleTHROMBOSIS RESEARCH. 131(4):342-348 (2013)journal articl

Differences in the function and secretion of congenital aberrant fibrinogenemia between heterozygous gamma D320G (Okayama II) and gamma Delta N319-Delta D320 (Otsu I)

Background: We encountered two patients with hypodysfibrinogenemia and designated them as Okayama II and Otsu I. Although the affected residue(s) in Okayama II and Otsu I overlapped, functionally determined fibrinogen levels and the ratio of functionally to immunologically determined plasma fibrinogen levels were markedly different.Methods: DNA sequence and functional analyses were performed for purified plasma fibrinogen. A recombinant protein was synthesized in Chinese hamster ovary (CHO) cells to determine the secretion of variant fibrinogens.Results: A heterozygous A>G in FGG, resulting in gamma 320Asp>Gly for Okayama II, and a heterozygous deletion of AATGAT in FGG, resulting in the deletion of gamma Asn319 and gamma Asp320 (gamma Delta N319-Delta D320) for Otsu I, were obtained. SDS-PAGE and Coomassie staining revealed that the variant gamma-chain was not clear in Okayama II, but was clearly present in Otsu I. The lag period for the fibrin polymerization of Okayama II was slightly slower than that of the normal control, whereas Otsu I fibrinogen indicated no polymerization within 30 min. Both variant gamma-chains were synthesized in CHO cells and assembled into fibrinogen; however, the fibrinogen concentration ratio of the medium/cell lysate of gamma 320Gly was six-fold lower than that of gamma Delta N319-Delta D320.Conclusions: We concluded that the plasma fibrinogen of Okayama II, constituted by a lower ratio of the variant gamma-chain, led to the almost normal functioning of fibrin polymerization. However, the plasma fibrinogen of Otsu I, with a higher ratio of the variant gamma-chain, led to marked reductions in fibrin polymerization. (C) 2015 Elsevier Ltd. All rights reserved.THROMBOSIS RESEARCH. 136(6):1318-1324 (2015)journal articl

A novel frameshift mutation in the fibrinogen γC terminal region, FGG c.1169_1170 del AT, leading to hypofibrinogenemia

ArticleTHROMBOSIS RESEARCH.159:82-85(2017)journal articl

Genetic analyses of novel compound heterozygous hypodysfibrinogenemia, Tsukuba I: FGG c.1129+62_65 del AATA and FGG c.1299+4 del A

Epub 2016 Nov 5Introduction: Wefound a novel hypodysfibrinogenemia designated Tsukuba I caused by compound heterozygous nucleotide deletionswith 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 gamma'-chain, but not the.A-chain. AWestern blot analysis of plasma fibrinogen from our patient revealed an aberrant gamma-chain that migrated slightly faster than the normal B beta-chain. Materials andmethods: To clarify the complex genetic mechanismunderlying 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,gamma' 409.A (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 gamma' 409.A-CHOcells secreted variant fibrinogenmore 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.A-and gamma'-chains; moreover, the Ex-9 deletion causes hypodysfibrinogenemia due to the absence of normal.A-and gamma'-chain production (hypofibrinogenemia) and augmented aberrant.'-chain production (dysfibrinogenemia). (C) 2016 Elsevier Ltd. All rights reserved.ArticleTHROMBOSIS RESEARCH. 148:111-117 (2016)journal articl

The fibrous form of intracellular inclusion bodies in recombinant variant fibrinogen-producing cells is specific to the hepatic fibrinogen storage disease-inducible variant fibrinogen

Fibrinogen storage disease (FSD) is a rare disorder that is characterized by the accumulation of fibrinogen in hepatocytes and induces liver injury. Six mutations in the γC domain (γG284R, γT314P, γD316N, the deletion of γG346-Q350, γG366S, and γR375W) have been identified for FSD. Our group previously established γ375W fibrinogen-producing Chinese hamster ovary (CHO) cells and observed aberrant large granular and fibrous forms of intracellular inclusion bodies. The aim of this study was to investigate whether fibrous intracellular inclusion bodies are specific to FSD-inducible variant fibrinogen. Thirteen expression vectors encoding the variant γ-chain were stably or transiently transfected into CHO cells expressing normal fibrinogen Aα- and Bβ-chains or HuH-7 cells, which were then immunofluorescently stained. Six CHO and HuH-7 cell lines that transiently produced FSD-inducible variant fibrinogen presented the fibrous (3.2?22.7 and 2.1?24.5%, respectively) and large granular (5.4?25.5 and 7.7?23.9%) forms of intracellular inclusion bodies. Seven CHO and HuH-7 cell lines that transiently produced FSD-non-inducible variant fibrinogen only exhibit the large granular form. These results demonstrate that transiently transfected variant fibrinogen-producing CHO cells and inclusion bodies of the fibrous form may be useful in non-invasive screening for FSD risk factors for FSD before its onset.ArticleINTERNATIONAL JOURNAL OF HEMATOLOGY.105:758-768(2017)journal articl

Molecular analysis of afibrinogenemic mutations caused by a homozygous FGA1238 bp deletion, and a compound heterozygous FGA1238 bp deletion and novel FGA c.54+3A > C substitution

We identified two afibrinogenemic girls in two Japanese families and performed molecular analysis to clarify the mechanisms of fibrinogen defects. Genetic analyses were performed by PCR amplification of the fibrinogen gene and DNA sequence analysis. To analyze the mechanisms of mature fibrinogen defects in plasma, we cloned minigenes from the proposita's PCR-amplified DNA, transfected them into CHO cells, and sequenced the cDNA amplified with the RT reaction followed by PCR. Sequence analyses indicated that one was caused by a homozygous 1238 bp deletion of the fibrinogen A alpha-chain gene (FGA Delta 1238) and the other was a compound heterozygous FGA Delta 1238 and novel FGA c.54+3A > C substitution. The minigene corresponding to FGA Delta 1238 generates two aberrant mRNAs, both of which may induce a frameshift and terminate prematurely. In contrast, the minigene corresponding to FGA c.54+3A > C generates two aberrant mRNAs, one of which may induce a frameshift and terminate prematurely, and the other uses a cryptic 5' splice site in exon 1, resulting in the deletion of six amino acids in signal peptides. Molecular analyses of both genetic variants suggest that the lack of a mature A alpha-chain, impaired assembly, and/or secretion of the fibrinogen molecule may lead to afibrinogenemia.ArticleINTERNATIONAL JOURNAL OF HEMATOLOGY. 96(1):39-46 (2012)journal articl

Pathophysiological Investigation of the Gastric Surface Mucous Gel Layer of Patients with Helicobacter pylori Infection by Using Immunoassays for Trefoil Factor Family 2 and Gastric Gland Mucous Cell-Type Mucin in Gastric Juice

Background The trefoil factor family (TFF) 2 protein is produced by gastric gland mucous cells (GMCs), and the secreted TFF2 shares a mucosal barrier function with GMC-type mucin. Recently, we presented an enzyme-linked immunosorbent assay (ELISA) method for measurement of GMC-type mucin in the gastric juice. Aims We aimed to develop an ELISA for TFF2 and to assess pathophysiological changes in the gastric surface mucous gel layer (SMGL) of patients with Helicobacter pylori infection. Methods The distribution of TFF2 and GMC-type mucin in the SMGL was immunohistochemically determined. The ELISA for TFF2 was based on a polyclonal goat antibody. Recombinant TFF2 was employed to prepare the calibrators. TFF2 and GMC-type mucin in the gastric juice in healthy individuals (n = 33) and patients with gastritis (n = 37), gastric ulcer (n = 16), and duodenal ulcer (n = 10) were assayed using ELISA. Results TFF2 and GMC-type mucin were immunohistochemically co-localized in the gastric SMGL and GMCs. The TFF2 levels in the patients were significantly higher than those in the healthy individuals. Further, the TFF2 levels in the H. pylori-positive patients were significantly higher than those in the H. pylori-negative patients, and decreased after the eradication of the infection. GMC-type mucin levels showed a tendency similar to that of TFF2 levels. Conclusions The upregulation of TFF2 and GMC-type mucin secretion may reflect the response of the gastric mucosa to H. pylori-induced injuries. TFF2 and GMC-type mucin secreted into the SMGL may protect the gastric mucosa against H. pylori.ArticleDIGESTIVE DISEASES AND SCIENCES. 56(12):3498-3506 (2011)journal articl

Acquired dysfibrinogenemia: monoclonal λ-type IgA binding to fibrinogen caused lower functional plasma fibrinogen level and abnormal clot formation

ArticleInternational journal of hematology. 112(1): 96-104. (2020)journal articl

Screening method for congenital dysfibrinogenemia using clot waveform analysis with the Clauss method

ArticleInternational journal of laboratory hematology. 43(2): 281-289(2021)journal articl

Heterozygous B beta-chain C-terminal 12 amino acid elongation variant, B beta X462W (Kyoto VI), showed dysfibrinogenemia

A heterozygous patient with dysfibrinogenemia with slight bleeding and no thrombotic complications was diagnosed with fibrinogen Kyoto VI (K-VI). To elucidate the genetic mutation(s) and characterize the variant protein, we performed the following experiments and compared with identical and similar variants that have already been reported. The proposita's PCR-amplified DNA was analyzed by sequencing and her purified plasma fibrinogen underwent SDS-PAGE followed by immunoblotting, fibrin polymerization, and scanning electron microscopic observation of fibrin clot and fibers. Sequence analyses showed that K-VI fibrinogen substituted W (TGG) for terminal codon (TAG), resulting in 12 amino acid elongation 462-473 (WSPIRRFLLFCM) in the B beta-chain. Protein analyses indicated that the presence of some albumin-binding variant fibrinogens and a dimeric molecule of variant fibrinogens reduced fibrin polymerization, with a thinner fiber and aberrant fibrin network. These results are almost the same as for the identical variant of Magdeburg, however, different from the similar variant of Osaka VI [ 12 amino acid elongation 462-473 (KSPIRRFLLFCM) in the B beta-chain] in the presence of variant forms and clot structure. We speculate the side-chain difference at 462 residues, W in K-VI, K in Osaka VI, and/or the difference in the presence of disulfide bridged forms of variant fibrinogens, led to the notable difference in the fibrin bundle network. Although a strong evolutional and structural association between B beta-chain and gamma-chain molecules is established, the corresponding recombinant 15 residue elongation variants of the fibrinogen gamma-chain showed reduced assembly and secretion.ArticleBLOOD COAGULATION & FIBRINOLYSIS. 23(1):87-90 (2012)journal articl