B-domain deleted factor VIII is aggregated and degraded through proteasomal and lysosomal pathways

2005 ◽  
Vol 93 (05) ◽  
pp. 824-832 ◽  
Author(s):  
Benoit Guillet ◽  
Cécile Ducasse ◽  
Nathalie Enjolras ◽  
Marie-Hélène Rodriguez ◽  
Véronique Rolli ◽  
...  
Keyword(s):  
Factor Viii ◽  
Light Chain ◽  
Cho Cells ◽  
Mammalian Cells ◽  
Mrna Synthesis ◽  
Extracellular Production ◽  
Single Chain ◽  
Cho Cell ◽  
Over Expression ◽  
Triton X

SummaryFactor VIII (FVIII) processing within mammalian cells is demonstrated to be much less efficient than proteins of similar size. The deletion of the B-domain from FVIII improves the level of production, due partly to the increase in mRNA synthesis. We aimed to characterise the cellular fate and the intracellular processing of the FVIII molecule devoid of B-domain. A B-domain deleted factor VIII (BDD-FVIII) possessing a furin consensus cleavage site in the connecting segment between the heavy and the light chain, was produced in CHO cell line. In such cells, FVIII was retained as two single chain products from which a majority was aggregated. The two species were located in Triton X-100 soluble (for 60–80%) and insoluble fractions (for 20–40%). The incubation of the expressing cells with tunicamycin (5 μg/ml) and the treatment of the intracellular species with a mixture of Neuraminidase and N-glycosidase-F revealed that both intracellular species were N-glycosylated. Furin over-expression neither diminished the intracellular FVIII contents nor improved its extracellular production. Intracellular FVIII was degraded through both lysosomal and proteasomal pathways as evidenced by inhibitor treatments (e.g. NH4Cl, leupeptin, clasto-Lactacystin β-lactone and MG-132), pulse-chase analysis and confocal observations. This study demonstrates that a BDD-FVIII expressed in CHO cells is inefficiently processed consecutively to intracellular aggregation, proteasomal degradation, and routage to lysosomes.

scholarly journals Characterization of des-(741–1668)-factor VIII, a single-chain factor VIII variant with a fusion site susceptible to proteolysis by thrombin and factor Xa

1995 ◽  
Vol 312 (1) ◽  
pp. 49-55 ◽  
Author(s):  
M J S H Donath ◽  
R T M de Laaf ◽  
P T M Biessels ◽  
P J Lenting ◽  
J W van de Loo ◽  
...  
Keyword(s):  
Factor Viii ◽  
Von Willebrand Factor ◽  
Heavy Chain ◽  
Light Chain ◽  
Factor Xa ◽  
Single Chain ◽  
Factor Ixa ◽  
Fusion Site ◽  
Von Willebrand ◽  
Willebrand Factor

A factor VIII variant has been characterized in which the heavy chain is directly fused to the light chain. Des-(741-1668)-factor VIII lacks the processing site at Arg1648, as Arg740 of the heavy chain is fused to Ser1669 of the light chain. The sequence of the fusion site is similar to that of other cleavage sites in factor VIII. The fusion site of des-(741-1668)-factor VIII was readily cleaved by both thrombin and factor Xa, and the same result was obtained for heavy chain cleavage. In contrast, des-(741-1668)-factor VIII cleavage by thrombin at position Arg1689 proceeded at a lower rate than the analogous cleavage by factor Xa, which presumably takes place at position Arg1721. The rate of cleavage at position Arg1689 by thrombin was also lower than that at the other processing sites. When des-(741-1668)-factor VIII was activated by thrombin, initial rates of factor Xa formation were similar to the rates obtained when plasma-derived factor VIII was activated by thrombin or factor Xa. Remarkably, activation of des-(741-1668)-factor VIII proceeded at a higher rate by factor Xa than by thrombin. These results indicate that factor VIII activation is strongly associated with cleavage at position Arg1689 or Arg1721. For the interaction between des-(741-1668)-factor VIII and von Willebrand factor, a Kd value of (0.8 +/- 0.3) x 10(-10) M was determined, which is similar to that of heterodimeric factor VIII. The affinity of single-chain des-(741-1668)-factor VIII for factor IXa was found to be 27 +/- 6 nM. The in vivo recovery and half-life of des-(741-1668)-factor VIII were assessed in guinea pigs. Upon infusion of des-(741-1668)-factor VIII at a dosage of 50 units/kg body weight, a rise of 1.0 +/- 0.3 unit/ml in factor VIII activity was obtained. The same recovery was determined for wild-type factor VIII. The half-life of des-(741-1668)-factor VIII was found to be 3 +/- 1 h, compared with 4 +/- 2 h for heterodimeric recombinant factor VIII. In conclusion, des-(741-1668)-factor VIII displays normal activity, is readily cleaved by thrombin and factor Xa at its fusion site, binds with high affinity to von Willebrand factor and factor IXa, and behaves like heterodimeric recombinant factor VIII in guinea pigs. By virtue of these properties, des-(741-1668)-factor VIII may prove useful for the treatment of bleeding episodes in patients with haemophilia A.

Factor VIII Arg2304 → His Binds to Phosphatidylserine and Is a Functional Cofactor in the Factor X-ase Complex

2001 ◽  
Vol 85 (02) ◽  
pp. 260-264 ◽  
Author(s):  
Deborah Lewis ◽  
Karen Moore ◽  
Thomas Ortel
Keyword(s):  
Factor Viii ◽  
Light Chain ◽  
Mammalian Cells ◽  
Exchange Chromatography ◽  
Light Chains ◽  
Factor X ◽  
Wild Type ◽  
Functional Protein ◽  
Type Factor ◽  
Circulating Levels

SummaryFour factor VIII light chain constructs containing hemophilia A mutations at R2304 and R2307 were prepared and expressed in mammalian cells. These mutations are located in a putative phosphatidylserine binding site identified by peptide studies (spanning amino acids 2303-2332). The levels of all four mutants in conditioned medium were significantly less than wild type by immunoprecipitation and ELISA. R2304H and wild type factor VIII light chains were concentrated by cation exchange chromatography from medium. R2304H and wild type factor VIII light chains bound immobilized phosphatidylserine similarly. The reconstituted cofactor activity of R2304H factor VIII light chain was slightly greater than wild type factor VIII light chain. These results are consistent with the recently reported crystal structure of factor VIII C2 domain that suggests R2304H is not directly involved in phospholipid binding. The observed clinical phenotype is probably due to decreased circulating levels of a functional protein.

Human antibodies with specificity for the C2 domain of factor VIII are derived from VH1 germline genes

Blood ◽  
2000 ◽  
Vol 95 (2) ◽  
pp. 558-563 ◽  
Author(s):  
Edward N. van den Brink ◽  
Ellen A. M. Turenhout ◽  
Julian Davies ◽  
Niels Bovenschen ◽  
Karin Fijnvandraat ◽  
...  
Keyword(s):  
Factor Viii ◽  
Light Chain ◽  
Neutralizing Antibodies ◽  
Chain Gene ◽  
Gene Repertoire ◽  
C2 Domain ◽  
Single Chain ◽  
Phage Display Technology ◽  
Light Chain Gene ◽  
Germline Genes

A serious complication in hemophilia care is the development of factor VIII (FVIII) neutralizing antibodies (inhibitors). The authors used V gene phage display technology to define human anti-FVIII antibodies at the molecular level. The IgG4-specific, variable, heavy-chain gene repertoire of a patient with acquired hemophilia was combined with a nonimmune, variable, light-chain gene repertoire for display as single-chain variable domain antibody fragments (scFv) on filamentous phage. ScFv were selected by 4 rounds of panning on immobilized FVIII light chain. Sequence analysis revealed that isolated scFv were characterized by VH domains encoded by germline genes DP-10, DP-14, and DP-88, all belonging to the VH1 gene family. All clones displayed extensive hypermutation and were characterized by unusually long CDR3 sequences of 20 to 23 amino acids. Immunoprecipitation revealed that all scFv examined bound to the C2 domain of FVIII. Furthermore, isolated scFv competed with an inhibitory murine monoclonal antibody for binding to the C2 domain. Even though scFv bound FVIII with high affinity, they did not inhibit FVIII activity. Interestingly, the addition of scFv diminished the inhibitory potential of patient-derived antibodies with C2 domain specificity. These results suggest that the epitope of a significant portion of anti-C2 domain antibodies overlaps with that of the scFv isolated in this study.

Phospholipid vesicles interfere with the binding of antibody fragments to the light chain of factor VIII

2005 ◽  
Vol 93 (05) ◽  
pp. 833-841 ◽  
Author(s):  
Deborah Lewis ◽  
Niels Bovenschen ◽  
Koen Mertens ◽  
Jan Voorberg ◽  
Thomas Ortel
Keyword(s):  
Factor Viii ◽  
Light Chain ◽  
Membrane Binding ◽  
Phospholipid Vesicles ◽  
C2 Domain ◽  
Wild Type ◽  
Single Chain ◽  
Type Protein ◽  
Wild Type Protein ◽  
C1 Domains

SummaryFactor VIII binds to phospholipid membranes through the C2 domain (S2173-Y2332). Residues M2199, F2200, L2251, L2252, V2223, W2313 and V2314 at the tips of β-hairpins and loops are thought to contribute to phospholipid membrane binding. Similarly, residues in the C2 domain of the homologous protein factor V form a phospholipid binding site, but residues in the A3 and C1 domains are also thought to contribute to membrane binding. Phage display technology was previously used to isolate factor VIII light chain specific single-chain variable domain fragments (scFv) from patients with factor VIII inhibitors. Phospholipid vesicles inhibited the binding of factor VIII to scFvsWR1 and WR16 (epitope: E2181-M2199) with half saturation values of 23 and 47 μM respectively. The single point mutant F2200A factor VIII light chain bound to WR1 and WR16 with a much lower affinity than wild type protein suggesting that residue F2200 is also included in the epitopes of these scFvs. Binding of factor VIII to C2-specific scFvsWR13 and EL14 (epitope: K2207-M2321) was not inhibited by phospholipid vesicles. Consistent with this, F2200A factor VIII light chain bound to these scFvs with the same affinity as the wild type protein. However, phospholipid vesicles also inhibited the binding of factor VIII to the A3-C1-specific scFvs KM36 (epitope: Q1778-D1840) and KM38 (epitope: S1690-N1777 and/or V1841-N2172) with half saturation values of 84 and 165 μM, respectively, suggesting that the A3 and/or C1 domains may contribute to membrane binding of the cofactor.

scholarly journals Generation and Characterization of Chimeric Antibodies against NS3, NS4, NS5, and Core Antigens of Hepatitis C Virus

2010 ◽  
Vol 17 (6) ◽  
pp. 1040-1047 ◽  
Author(s):  
Bailin Tu ◽  
Robert N. Ziemann ◽  
Bryan C. Tieman ◽  
David J. Hawksworth ◽  
Joan Tyner ◽  
...  
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Heavy Chain ◽  
Light Chain ◽  
Cho Cells ◽  
Free Medium ◽  
Cho Cell ◽  
Alanine Scanning Mutagenesis ◽  
Variable Regions ◽  
Chimeric Antibodies

ABSTRACT Mouse-human chimeric antibodies (cAbs) against hepatitis C virus (HCV) core, NS3 (nonstructural), NS4, and NS5 antigens were developed as quality control (QC) reagents to replace the use of human sera/plasma for Abbott HCV immunoassays. The cAb retains the mouse monoclonal antibody (MAb) specificity and affinity but still reacts in the existing HCV assay format, which measures human anti-HCV immunoglobulin. Mouse heavy-chain (VH) and light-chain (VL) variable regions of anti-HCV core, NS3, NS4, and NS5 antigens were PCR amplified from hybridoma lines and then cloned with human IgG1 heavy-chain (CH) and light-chain (CL) constant regions, respectively. A single mammalian expression plasmid containing both heavy-chain and light-chain immunoglobulin genes was constructed and transfected into dihydrofolate reductase (DHFR)-deficient Chinese hamster ovary (CHO) cells. The transfected CHO cells were selected using hypoxanthine- and thymidine-free medium and screened by an enzyme immunoassay (EIA). The clone secreting the highest level of antibody was isolated from the CHO transfectants and further subcloned. Each cAb-expressing CHO cell line was weaned into serum-free medium, and the cAb was purified by protein A affinity chromatography. The levels of cAb production for the various CHO cell lines varied from 10 to 20 mg/liter. Purified anti-HCV cAbs were tested with Abbott HCV immunoassays and showed reactivity. Moreover, yeast surface display combined with alanine-scanning mutagenesis was used to map the epitope at the individual amino acid level. Our results suggest that these HCV cAbs are ideal controls, calibrators, and/or QC reagents for HCV assay standardization.

LIPOPOLYSACCHARIDE-SENSITIVE SERINE-PROTEASE ZYMOGEN (FACTOR C) OF LIMULUS HEMOCYTES: IDENTIFICATION AND ALIGNMENT OF PROTEOLYTIC FRAGMENTS PRODUCED DURING THE ACTIVATION SHOW THAT IT IS A NOVEL TYPE OF SERINE-PROTEASE

1987 ◽  
Author(s):  
F Tokunaga ◽  
T Miyata ◽  
T Nakamura ◽  
T Morita ◽  
S Iwanaga
Keyword(s):  
Serine Protease ◽  
Heavy Chain ◽  
Light Chain ◽  
Interleukin 2 ◽  
Coagulation Factor ◽  
Clotting Factor ◽  
Single Chain ◽  
Terminal Sequence ◽  
A Chain ◽  
Factor C

Limulus clotting factor, factor C, is a lipopolysaccharide (LPS)-sensitive serine-protease zymogen present in the hemocytes. It is a two-chain glycoprotein (M.W. = 123,000) composed of a heavy chain (M.W. = 80,000) and a light chain (M.W. = 43,000) T. Nakamura et al. (1986) Eur. J. Biochem. 154, 511-521 .On further studies of this zymogen, a single-chain factor C (M.W. = 123,000) was identified by Western blotting technique. The heavy chain had an NH2-terminal sequence of Ser-Gly-Val-Asp-, which was consistent with the NH2-terminal sequence of the single-chain factor C, indicating that the heavy chain is located in the NH2-terminal part of the zymogen. The light chain had an NH22-terminal sequence of Ser-Ser-Gln-Pro-. Incubation of the two-chain zymogen with LPS resulted in the cleavage of a Phe-Ile bond between residues 72 and 73 of the light chain. Concomitant with this cleavage, the A (72.amino acids) and B chains derived from the light chain was formed. The complete amino acid sequence of the A chain was determined by automated Edman degradation. The A chain contained a typical segment which is similar structuraly to those a family of repeats in human β2 -glycoprotein I, complement factors B, Clr, Cls, H, C4b-binding protein, 02, coagulation factor XIII b subunit, haptoglobin a chain, and interleukin 2 receptor. The NH2-terminal sequence of the B chain was Ile-Trp-Asn-Gly-. This chain contained the serine-active site sequence of -ASP-Ala-Cys-Ser-Gly-Asp-SER-Gly-Gly-Pro-.These results indicate that limulus factor C exists in the hemocytes in a single-chain zymogen form and is converted to an active serine-protease by hydrolysis of a specific Phe-Ile peptide bond. The correlation of limulus factor C and mammalian complement proteins was also suggested.

scholarly journals Recombinant γY278H Fibrinogen Showed Normal Secretion from CHO Cells, but a Corresponding Heterozygous Patient Showed Hypofibrinogenemia

2021 ◽  
Vol 22 (10) ◽  
pp. 5218
Author(s):  
Tomu Kamijo ◽  
Takahiro Kaido ◽  
Masahiro Yoda ◽  
Shinpei Arai ◽  
Kazuyoshi Yamauchi ◽  
...  
Keyword(s):  
Cell Lines ◽  
Cho Cells ◽  
Fibrinogen Level ◽  
Culture Media ◽  
Chinese Hamster ◽  
Plasma Fibrinogen ◽  
Enzyme Linked Immunosorbent Assay ◽  
Cho Cell ◽  
Accelerated Degradation ◽  
Heterozygous Patient

We identified a novel heterozygous hypofibrinogenemia, γY278H (Hiroshima). To demonstrate the cause of reduced plasma fibrinogen levels (functional level: 1.12 g/L and antigenic level: 1.16 g/L), we established γY278H fibrinogen-producing Chinese hamster ovary (CHO) cells. An enzyme-linked immunosorbent assay demonstrated that synthesis of γY278H fibrinogen inside CHO cells and secretion into the culture media were not reduced. Then, we established an additional five variant fibrinogen-producing CHO cell lines (γL276P, γT277P, γT277R, γA279D, and γY280C) and conducted further investigations. We have already established 33 γ-module variant fibrinogen-producing CHO cell lines, including 6 cell lines in this study, but only the γY278H and γT277R cell lines showed disagreement, namely, recombinant fibrinogen production was not reduced but the patients’ plasma fibrinogen level was reduced. Finally, we performed fibrinogen degradation assays and demonstrated that the γY278H and γT277R fibrinogens were easily cleaved by plasmin whereas their polymerization in the presence of Ca2+ and “D:D” interaction was normal. In conclusion, our investigation suggested that patient γY278H showed hypofibrinogenemia because γY278H fibrinogen was secreted normally from the patient’s hepatocytes but then underwent accelerated degradation by plasmin in the circulation.

A Factor VIII Neutralizing Monoclonal Antibody and a Human Inhibitor Alloantibody Recognizing Epitopes in the C2 Domain Inhibit Factor VIII Binding to von Willebrand Factor and to Phosphatidylserine

1993 ◽  
Vol 69 (03) ◽  
pp. 240-246 ◽  
Author(s):  
Midori Shima ◽  
Dorothea Scandella ◽  
Akira Yoshioka ◽  
Hiroaki Nakai ◽  
Ichiro Tanaka ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Amino Acid ◽  
Factor Viii ◽  
Von Willebrand Factor ◽  
Light Chain ◽  
Amino Acid Residues ◽  
Amino Terminal ◽  
Neutralizing Monoclonal Antibody ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryA neutralizing monoclonal antibody, NMC-VIII/5, recognizing the 72 kDa thrombin-proteolytic fragment of factor VIII light chain was obtained. Binding of the antibody to immobilized factor VIII (FVIII) was completely blocked by a light chain-specific human alloantibody, TK, which inhibits FVIII activity. Immunoblotting analysis with a panel of recombinant protein fragments of the C2 domain deleted from the amino-terminal or the carboxy-terminal ends demonstrated binding of NMC-VIII/5 to an epitope located between amino acid residues 2170 and 2327. On the other hand, the epitope of the inhibitor alloantibody, TK, was localized to 64 amino acid residues from 2248 to 2312 using the same recombinant fragments. NMC-VIII/5 and TK inhibited FVIII binding to immobilized von Willebrand factor (vWF). The IC50 of NMC-VIII/5 for the inhibition of binding to vWF was 0.23 μg/ml for IgG and 0.2 μg/ml for F(ab)'2. This concentration was 100-fold lower than that of a monoclonal antibody NMC-VIII/10 which recognizes the amino acid residues 1675 to 1684 within the amino-terminal portion of the light chain. The IC50 of TK was 11 μg/ml by IgG and 6.3 μg/ml by F(ab)'2. Furthermore, NMC-VIII/5 and TK also inhibited FVIII binding to immobilized phosphatidylserine. The IC50 for inhibition of phospholipid binding of NMC-VIII/5 and TK (anti-FVIII inhibitor titer of 300 Bethesda units/mg of IgG) was 10 μg/ml.

Sign in / Sign up

Export Citation Format

Share Document