Expression of human factor IX in mice after injection of genetically modified myoblasts

Hemophilia B is an X chromosome-linked recessive bleeding disorder. To develop a somatic gene therapy for this disease, we have examined whether mouse skeletal myoblasts can serve as efficient vehicles for systemic delivery of recombinant factor IX. When mouse myoblasts (C2C12) transduced with a Moloney murine leukemia virus-based vector containing the bacterial beta-galactosidase gene were injected into mouse skeletal muscles, they fused with the existing and regenerating myofibers and continued to express beta-galactosidase. C2C12 myoblasts that were infected with recombinant retroviruses containing a human factor IX cDNA secreted biologically active human factor IX cDNA secreted biologically active human factor IX into the culture medium at a rate of 2.6 micrograms per 10(6) cells per day. Myotubes derived from these cells in culture continued to express human factor IX (0.68 micrograms/day from myotubes derived from 10(6) C2C12 cells). After injection of the transduced C2C12 myoblasts into skeletal muscles of mice, the systemic level of recombinant human factor IX was found to be as high as approximately 1 microgram/ml of serum. These results provide the rationale for using skeletal myoblasts as an efficient gene delivery vehicle in the somatic gene therapy for hemophilia B.

Deficiencies in factors IX and VIII: what is now known

Genetic defects both gross and subtle have recently been identified in about 900 patients with hemophilia A or B. The defects, which include deletions, insertions, and point mutations, reveal much about genetic structure-function relationships in hemophilia. These insights will lead to improved treatment of bleeding disorders and perhaps to their cure.

Phase 1 clinical tests of influenza MDP-virosome vaccine (KD-5382)

MDP-virosome vaccine, which contains haemagglutinin (HA) and neuraminidase (NA) antigens isolated from influenza virus combined with 6-O-(2-tetradecylhexadecanoyl)-N-acetylmuramoyl-L-alanyl-D-isoglutamine) (B30-MDP) and cholesterol was tested, in comparison with a currently used HA vaccine, for immunogenicity and adverse reactions on 77 adult male volunteers. The volunteers were divided into eight groups, and each individual was injected subcutaneously once, or twice at a 4 week interval, in their upper arm with one of seven different MDP-virosome vaccine preparations or with HA vaccine as control. Of the three virus strains used as vaccine antigens, MDP-virosome vaccines induced higher haemagglutination inhibiting (HI) antibody to A/Yamagata/120/86 (H1N1) and A/Fukuoka/C29/86 (H3N2) than did HA vaccine, whereas it induced lower HI antibody to B/Nagasaki/1/87, comparable with that induced by HA vaccine. Regarding local adverse reactions, MDP-virosome vaccinees frequently developed mild local pain, reddening and swelling, which disappeared within 5 days; as regards systemic no adverse reactions, leucocytosis developed among the MDP-virosome vaccines, but no other reactions were observed. The leucocytosis may have been caused by the pharmacoimmunological activity of B30-MDP derivatives.

Expression of human factor IX in rat capillary endothelial cells: toward somatic gene therapy for hemophilia B

In aiming to develop a gene therapy approach for hemophilia B, we expressed and characterized human factor IX in rat capillary endothelial cells (CECs). Moloney murine leukemia virus-derived retrovirus vectors that contain human factor IX cDNA linked to heterologous promoters and the neomycin-resistant gene were constructed and employed to prepare recombinant retroviruses. Rat CECs and NIH 3T3 cells infected with these viruses were selected with the neomycin analogue, G418 sulfate, and tested for expression of factor IX. A construct with the factor IX cDNA under direct control by long terminal repeat gave the highest level of expression (0.84 and 3.6 micrograms per 10(6) cells per day for CECs and NIH 3T3 cells, respectively) as quantitated by immunoassays as well as clotting activity assays. A single RNA transcript of 4.4 kilobases predicted by the construct and a recombinant factor IX of 68 kilodaltons identical to purified plasma factor IX were found. The recombinant human factor IX produced showed full clotting activity, demonstrating that CECs have an efficient mechanism for posttranslational modifications, including gamma-carboxylation, essential for its biological activity. These results, in addition to other properties of the endothelium, including large number of cells, accessibility, and direct contact with the circulating blood, suggest that CECs can serve as an efficient drug delivery vehicle producing factor IX in a somatic gene therapy for hemophilia B.

Hepsin, a cell membrane-associated protease. Characterization, tissue distribution, and gene localization

Hepsin, a putative membrane-bound serine protease, was originally identified as a human liver cDNA clone (Leytus, S.P., Loeb, K.R., Hagen, F.S., Kurachi, K., and Davie, E.W. (1988) Biochemistry 27, 1067-1074). In the present study the human hepsin gene was localized to chromosome 19 at q11-13.2. The messenger RNA of hepsin is 1.85 kilobases in size and present in most tissues, with the highest level in liver. Hepsin is synthesized as a single polypeptide chain, and its mature form of 51 kDa was found in various mammalian cells including HepG2 cells and baby hamster kidney cells. It is present in the plasma-membrane in a molecular orientation of type II membrane-associated proteins, with its catalytic subunit (carboxyl-terminal half) at the cell surface, and its amino terminus facing the cytosol. Hepsin is found neither in cytosol nor in culture media. The results obtained suggest that hepsin has an important role(s) in cell growth and function.

The major component of a large, intracellular proteinase accumulated by inhibitors is a complex of alpha 2-macroglobulin and thrombin

A large, intracellular proteinase accumulated by inhibitors (PABI) was found in cultured mammalian cells as a large, multicatalytic proteinase with a greatly elevated concentration in the presence of small peptide proteinase inhibitors (Tsuji and Kurachi (1989) J. Biol. Chem. 264, 16093). Electron microscopic analysis showed that the tertiary structure of PABI highly resembled that of alpha 2-macroglobulin complexed with a proteinase(s). Isolation of the anti-PABI cross-reacting material from calf serum added to the culture media of baby hamster kidney cells further supported that the primary component of PABI was alpha 2-macroglobulin. Immunoblot analyses and the substrate specificity of PABI indicated that the major proteinase component contained in PABI was thrombin. When alpha 2-macroglobulin was added to the PABI-depleted serum, a significant accumulation or a degradation of the intracellular alpha 2-macroglobulin was observed in the presence or absence of leupeptin, respectively. Similarly, when thrombin was added to the PABI-depleted fetal calf serum supplemented with fresh alpha 2-macroglobulin, a significant amount of intracellular thrombin was found only in the presence of leupeptin. These results indicate that the major component of the intracellular PABI molecules is a complex of alpha 2-macroglobulin with thrombin which is internalized from the culture media. Intracellular accumulation of PABI, therefore, is a phenomenon primarily relevant to the culture cells. Whether or not PABI is also generated in certain physiological or pathological conditions requires further study.

Characterization of a mouse factor IX cDNA and developmental regulation of the factor IX gene expression in liver

A mouse factor IX cDNA was isolated and characterized. The cDNA was 1,837 bp in length and contained the coding region as well as short 5' and 3' untranslated sequences. Northern blot analysis of liver RNA showed two mRNA species of 3.2 kb (major) and 2.2 kb (minor) for the mouse factor IX. An antisense RNA probe prepared from the mouse cDNA was employed to determine the steady state level of factor IX mRNA in mouse liver at various developmental stages. The factor IX mRNA level was very low (2-5% of the adult level) during the gestational period until day -3 (gestational day 17) followed by a rapid increase at day -2 through birth. This phase of rapid increase was followed by a gradual increase before it reached the adult level at around 20 to 24 days. At birth, the factor IX mRNA level was found to be at about 43% of that of the adult. The mRNA levels in mouse liver agreed well with the plasma factor IX activity levels. These results indicate that reduced factor IX activity in newborns is due to the low levels of factor IX mRNA available for translation.

Preparation and antitumor activity of hydroxyethylated derivatives of 6-branched (1----3)-beta-D-glucan, SSG, obtained from the culture filtrate of Sclerotinia sclerotiorum IFO 9395

SSG is an antitumor branched (1----3)-beta-D-glucan obtained from the culture filtrate of Sclerotinia sclerotiorum IFO 9395. Hydroxyethylation of SSG higher than MS 0.45 (MS value represents molar ratio of hydroxyethyl group vs. glucosyl group) by ethyleneoxide in aqueous sodium hydroxide lose the antitumor activity. Degradation of branching point of hydroxyethylated SSG (HE-SSG) by the sequential treatments of periodate oxidation, borohydride reduction, and mild acid hydrolysis of these derivatives regenerated the antitumor activity. These results directly demonstrated that the branching point covered, at least a part of, the dormant active site of SSG.

Structural and functional basis of the developmental regulation of human coagulation factor IX gene: factor IX Leyden

Hemophilia B Leyden is characterized by unusual developmental regulation of factor IX synthesis in affected individuals. One family affected with the hemophilia B Leyden phenotype was found to have a specific single-base mutation (G----A) at nucleotide -6 of the factor IX gene. The mutation site was found in a small region of the 5'-untranslated sequence designated the Leyden-specific region (LS region). This region, approximately 40 base pairs in length, contains the unique mutation sites of all the known factor IX Leyden genes (five families) analyzed to date. This fact strongly suggests that the LS region is directly or indirectly involved in the developmental regulation of factor IX biosynthesis. Base changes at nucleotide -20 as well as at nucleotide -6 and deletions of the 3' half of the LS region reduced expression activity of the factor IX gene to approximately 15-31% that of the normal control, as assessed in a cultured cell (HepG2) expression system. The LS region binds at least two proteins. Androgen significantly increased the transcriptional activities of both mutant and normal factor IX genes in a concentration-dependent manner.

Functional characterization of the 5'-regulatory region of human factor IX gene

Functional characterization of the 5'-regulatory region of the human factor IX gene was carried out by a series of gene dissection analyses. The region extending from -175 to -274 of the 5' end flanking sequence is required for the expression of this gene. Within this region, sequence elements AGCCACT at -238 and TCAAAT at -187 were assigned as the functional CAAT box and TATA box, respectively. The transcription initiation site was found to be at -150 for the factor IX chloramphenicol acetyltransferase chimeric gene. A negative regulatory (silencer) activity was located in the region spanning from 1.4 to 1.7 kilobases upstream of the promoter region. This region contains a short sequence element (ATCCTCTCC) known to have such activity. A strong promoter on the opposite strand was also located about 500 base pairs upstream of the promoter. The expression of factor IX gene was highly liver specific, as assessed by Northern blot analysis. Short sequence elements (TGGACC and CTTTGGACT) homologous to the known liver-specific elements were located in the vicinity of the defined promoter region.

Isolation and characterization of a novel large protease accumulated in mammalian cells in the presence of inhibitors

We have isolated and characterized a novel, large, multicatalytic protease from mammalian cells. This protease was designated PABI (protease accumulated by inhibitors). When baby hamster kidney (BHK) cells were grown in medium containing leupeptin, a potent serine-cysteine protease inhibitor, the trypsin-like protease activity (PABI) in the cells increased its level more than 100-fold over the control. This increase was also observed in other cultured cells such as COS, HepG2, and skin fibroblast cells. The activity was also elevated by treatment with other protease inhibitors including chymostatin or trans-epoxysuccinyl-L-leucylamide-(4-guanidino)butane. Immunoblot analysis, by employing antisera prepared against the purified PABI, also showed a concomitant increase of this protein in BHK, COS, and HepG2 cells on leupeptin treatment. PABI was purified to a homogeneous state from leupeptin-treated BHK cells. PABI is a glycoprotein of molecular weight 700,000. PABI was found to be a multimer of a major subunit of apparent Mr of 84,000, as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electron microscopic analysis. PABI dissociates into subunits only under reducing conditions in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. PABI has both trypsin-like and chymotrypsin-like protease activities toward synthetic substrates. Both activities were inhibited by phenylmethanesulfonyl fluoride, aprotinin, bovine pancreas trypsin inhibitor, and chymostatin. Leupeptin inhibited only the trypsin-like activity of PABI. p-Chloromercuribenzoate had no effect on either activity. Furthermore, PABI degraded collagen type I and fibronectin. These results indicate that PABI is a novel protease which differs from any known proteases including cytosolic high molecular weight proteases. The physiological function of PABI is yet to be determined.

[Evaluation of the internal carotid artery blood flow velocity waveforms using continuous-wave Doppler ultrasound in pregnant women]

The internal carotid artery blood flow velocity waveforms were measured with continuous-wave Doppler ultrasound in 17 normal nonpregnant and 50 pregnant women. 1) The measurement of the blood flow velocities in the pregnant women revealed a characteristic pattern. That is, in the women in the early pregnant stage (less than 16 weeks' gestation, n = 13), the velocity was lower than that of nonpregnant women. In the middle pregnant stage (16 to 27 weeks' gestation, n = 18), the velocity became higher than in the early stage and in the late stage (equal to and more than 28 weeks' gestation, n = 19), it again became slower. 2) The initial systolic peak blood velocity (S1), end-diastolic blood velocity (d), time averaged maximal blood velocity (M), Pourcelot ratio (PR), systolic-diastolic ratio (S/D) and pulsatility index (PI) were calculated and did not show laterality in any group. 3) PR, S/D and PI of the women in the early stages of pregnancy were higher than those of nonpregnant women, indicating that the cerebral vascular resistance became higher in early pregnancy. This technique presented the possibility of the assessment of the cerebral blood circulation in pregnant women.

Factor IXPortland: a nonsense mutation (CGA to TGA) resulting in hemophilia B

Male siblings with severe hemophilia b were studied for the molecular defect responsible for their disorder. To define the precise DNA alteration, a 362-bp fragment in the first part of exon VIII of the factor IX gene was amplified and sequenced. A single-base-pair substitution of C----T at the nucleotide sequence 30875 was found which resulted in a nonsense mutation (TGA) and terminated the protein synthesis of factor IX at amino acid residue 252. The single-base change occurred as a classic CG dinucleotide alteration to TG (or CA), a common mechanism for point mutations in mammals.

Human genes for complement components C1r and C1s in a close tail-to-tail arrangement

Complementary DNA clones for human C1s were isolated from cDNA libraries that were prepared with poly(A)+ RNAs of human liver and HepG2 cells. A clone with the largest cDNA insert of 2664 base pairs (bp) was analyzed for its complete nucleotide sequence. It contained 202 bp of a 5' untranslated region, 45 bp of coding for a signal peptide (15 amino acid residues), 2019 bp for complement component C1s zymogen (673 amino acid residues), 378 bp for a 3' untranslated region, a stop codon, and 17 bp of a poly(A) tail. The amino acid sequence of C1s was 40.5% identical to that of C1r, with excellent matches of tentative disulfide bond locations conserving the overall domain structure of C1r. DNA blotting and sequencing analyses of genomic DNA and of an isolated genomic DNA clone clearly showed that the human genes for C1r and C1s are closely located in a "tail-to-tail" arrangement at a distance of about 9.5 kilobases. Furthermore, RNA blot analyses showed that both C1r and C1s genes are primarily expressed in liver, whereas most other tissues expressed both C1r and C1s genes at much lower levels (less than 10% of that in liver). Multiple molecular sizes of specific mRNAs were observed in the RNA blot analyses for both C1r and C1s, indicating that alternative RNA processing(s), likely an alternative polyadenylylation, might take place for both genes.

DNA analysis of seven patients with hemophilia B who have anti-factor IX antibodies: relationship to clinical manifestations and evidence that the abnormal gene was inherited

We have investigated genomic DNA samples of 24 patients with hemophilia B (factor IX deficiency), including seven patients with anti-factor IX antibodies (inhibitors), by molecular probes. Seventeen patients without inhibitors against factor IX and three patients with inhibitor showed no abnormalities in their restriction fragments generated by digestions of the genomic DNA by BamHl, EcoRl, Mspl, or Taql and hybridized with a factor IX cDNA probe (pHFIX). The remaining four patients with inhibitors were found to have gross deletions of the factor IX gene. Among those four patients, two were from the same family. Quantitative Southern blotting clearly showed that the abnormal gene was inherited in this family. DNA from the mother of another patient with deletion of the factor IX gene showed normal gene dosage, indicating that the mutation must have occurred at the mother's germ cells. The genomic DNA samples of four patients with gross factor IX gene deletions were found to lack the entire factor IX gene as analyzed with a factor IX cDNA as well as with a 3'-genomic factor IX fragment as probes. The hypoxanthine phosphoribosyltransferase (HPRT) gene probe, however, was found to hybridize with all of these DNA samples, indicating that the deletions in these genomic DNA samples had not extended to the region containing the HPRT gene locus in q27 proximal to the factor IX gene locus on the X chromosome. Several clinical characteristics were compared between inhibitor cases with gene deletion and inhibitor cases without obvious gene deletion.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of human angiogenin in cultured baby hamster kidney cells

Baby hamster kidney cells were transformed with DNA sequences derived from the gene for human angiogenin. Expression was under the transcriptional control of the inducible mouse metallothionein 1 promoter. Recombinant angiogenin was purified and shown to be chemically, biologically, and enzymatically indistinguishable from the natural product. The large-scale production of recombinant angiogenin achieved should facilitate detailed studies into the structure-function relationships of this potent angiogenic molecule.

An insertion within the factor IX gene: hemophilia BEl Salvador

A patient with moderate to severe hemophilia B has been found to have a large insertion within his factor IX gene. The site of insertion is located in a DNA segment of approximately 0.8 kb between exon IV and an EcoRI site within intron D. The size of the DNA insertion is approximately 6 kb, and it contains at least two TaqI sites, two EcoRI sites, and one HindIII site. The insert probably originates from outside the FIX gene and does not represent an internal duplication. We propose that this abnormal FIX gene be called FIX El Salvador in recognition of the birthplace of the patient.