Genetic mechanisms of age regulation of human blood coagulation factor IX

Abnormal clotting of the intrinsic/contact pathway in Alzheimer disease patients is related to cognitive ability

Alzheimer disease (AD) is a neurodegenerative disorder characterized by extracellular β-amyloid (Aβ) deposition. Although peripheral inflammation and cerebrovascular pathology are reported in AD, there is a lack of plasma biomarkers in this field. Because the contact system is triggered in patient plasma, we hypothesized that the hemostasis profile could be a novel biomarker in AD. Here, we assessed the clotting profile in plasma from AD patients and age-matched controls. Utilizing clinically relevant assays, thromboelastography and activated partial thromboplastin time, we found impaired clot initiation and formation rate in AD patient plasma. These coagulation end points correlated with cerebrospinal fluid neurofilament-light levels and cognition and were more profound in younger AD patients. Ex vivo intrinsic clotting of plasma from AD mice expressing human amyloid precursor protein (APP) was also delayed in an age-dependent manner, suggesting that this phenotype is related to APP, the parent protein of Aβ. Further analysis of coagulation factors in human plasma indicated that endogenous inhibitor(s) of factors XII and XI in AD plasma contribute to this delayed clotting. Together, these data suggest that delayed clotting in young AD patients is a novel biomarker and that therapies aimed to correct this phenotype might be beneficial in this patient population. Follow-up studies in additional AD patient cohorts are warranted to further evaluate these findings.

Factor X heterozygous mutation in a patient with potential risk of bleeding: A case report

RATIONALE

Factor X (FX) deficiency is a rare autosomal recessive bleeding disorder. The majority of patients carry a missense mutation in F10, and patients with bleeding disorders are either homozygous or compound heterozygous for F10. Nonsense mutations are exceptionally rare, and a heterozygous nonsense mutation is not considered to cause bleeding disorders.

PATIENT CONCERNS

A 35-year-old Japanese female with an incidental hemorrhage after gynecologic polypectomy was referred to our hospital.

DIAGNOSES

Following differential diagnostic workup, including cross-mixing test, congenital FX deficiency was strongly suspected.

INTERVENTION

Coagulation tests and mutation analyses were conducted for the patient and her parents.

OUTCOMES

Mutation analysis revealed that she carried a heterozygous nonsense mutation in F10. Pedigree analysis revealed that the mutation was inherited from her mother although there was no familial history of bleeding or hemostatic disturbance.

LESSONS

Hemostatic disturbance may occur even in a patient with heterozygous F10. Because heterozygous nonsense mutation in F10 is expected to be hidden in an apparently healthy population, as observed in our patient, unexpected hemostatic disturbance may occur, particularly during the use of direct oral anticoagulant (DOAC)-targeting factor Xa for thrombotic diseases. FX activity should be evaluated before prescribing DOACs to patients.

DNA methylome and transcriptome sequencing in human ovarian granulosa cells links age-related changes in gene expression to gene body methylation and 3'-end GC density

Diminished ovarian function occurs early and is a primary cause for age-related decline in female fertility; however, its underlying mechanism remains unclear. This study investigated the roles that genome and epigenome structure play in age-related changes in gene expression and ovarian function, using human ovarian granulosa cells as an experimental system. DNA methylomes were compared between two groups of women with distinct age-related differences in ovarian functions, using both Methylated DNA Capture followed by Next Generation Sequencing (MethylCap-seq) and Reduced Representation Bisulfite Sequencing (RRBS); their transcriptomes were investigated using mRNA-seq. Significant, non-random changes in transcriptome and DNA methylome features are observed in human ovarian granulosa cells as women age and their ovarian functions deteriorate. The strongest correlations between methylation and the age-related changes in gene expression are not confined to the promoter region; rather, high densities of hypomethylated CpG-rich regions spanning the gene body are preferentially associated with gene down-regulation. This association is further enhanced where CpG regions are localized near the 3ʹ-end of the gene. Such features characterize several genes crucial in age-related decline in ovarian function, most notably the AMH (Anti-Müllerian Hormone) gene. The genome-wide correlation between the density of hypomethylated intragenic and 3ʹ-end regions and gene expression suggests previously unexplored mechanisms linking epigenome structure to age-related physiology and pathology.

Age-related expression analysis of mouse liver nuclear protein binding to 3'-untranslated region of Period2 gene

In mammals, both circadian rhythm and aging play important roles in regulating time-dependent homeostasis. We previously discovered an age-related increase element binding protein, hnRNP A3, which binds to the 3'-untranslated region (UTR) of blood coagulation factor IX (FIX). Here, we describe other members of this protein family, hnRNP C and hnRNP H, which bind to the 3'-UTR of the mouse circadian clock gene Period 2 (mPer2). RNA electrophoretic mobility shift assays using a (32)P-labeled Per2 RNA probe coupled with two-dimensional gel electrophoresis followed by MALDI-TOF/MS peptide mass fingerprint analysis was used to analyze these proteins. Western blotting suggested that the total expression of these proteins in mouse liver cell nuclei does not increase with age. Two-dimensional gel electrophoresis analysis of age-related protein expression showed that many isoforms of these proteins exist in the liver and that each protein exhibits a complex age-related expression pattern. These results suggest that many isoforms of proteins are regulated by different aging systems and that many age regulation systems function in the liver.

Animal models of hemophilia

The X-linked bleeding disorder hemophilia is caused by mutations in coagulation factor VIII (hemophilia A) or factor IX (hemophilia B). Unless prophylactic treatment is provided, patients with severe disease (less than 1% clotting activity) typically experience frequent spontaneous bleeds. Current treatment is largely based on intravenous infusion of recombinant or plasma-derived coagulation factor concentrate. More effective factor products are being developed. Moreover, gene therapies for sustained correction of hemophilia are showing much promise in preclinical studies and in clinical trials. These advances in molecular medicine heavily depend on availability of well-characterized small and large animal models of hemophilia, primarily hemophilia mice and dogs. Experiments in these animals represent important early and intermediate steps of translational research aimed at development of better and safer treatments for hemophilia, such a protein and gene therapies or immune tolerance protocols. While murine models are excellent for studies of large groups of animals using genetically defined strains, canine models are important for testing scale-up and for long-term follow-up as well as for studies that require larger blood volumes.

Heterogeneous nuclear ribonucleoprotein A3 is the liver nuclear protein binding to age related increase element RNA of the factor IX gene

Background

In the ASE/AIE-mediated genetic mechanism for age-related gene regulation, a recently identified age-related homeostasis mechanism, two genetic elements, ASE (age-related stability element) and AIE (age-related increase element as a stem-loop forming RNA), play critical roles in producing specific age-related expression patterns of genes.

Principal Finding

We successfully identified heterogeneous nuclear ribonucleoprotein A3 (hnRNP A3) as a major mouse liver nuclear protein binding to the AIE-derived RNAs of human factor IX (hFIX) as well as mouse factor IX (mFIX) genes. HnRNP A3 bound to the AIE RNA was not phosphorylated at its Ser³⁵⁹, while hnRNP A3 in the mouse liver nuclear extracts was a mixture of phosphorylated and unphosphorylated Ser³⁵⁹. HepG2 cells engineered to express recombinant hFIX transduced with adenoviral vectors harboring an effective siRNA against hnRNP A3 resulted in a substantial reduction in hFIX expression only in the cells carrying a hFIX expression vector with AIE, but not in the cells carrying a hFIX expression vector without AIE. The nuclear hnRNP A3 protein level in the mouse liver gradually increased with age, while its mRNA level stayed age-stable.

Conclusions

We identified hnRNP A3 as a major liver nuclear protein binding to FIX-AIE RNA. This protein plays a critical role in age-related gene expression, likely through an as yet unidentified epigenetic mechanism. The present study assigned a novel functional role to hnRNP A3 in age-related regulation of gene expression, opening up a new avenue for studying age-related homeostasis and underlying molecular mechanisms.

Intrinsic clotting factors in dependency of age, sex, body mass index, and oral contraceptives: definition and risk of elevated clotting factor levels

Elevated clotting factors have been demonstrated to be a risk factor for venous thromboembolism (VTE). The aim of our study was to investigate the impact of age, sex, body mass index, and oral contraceptives on the clotting factor activities of factors VIII, IX, XI, and XII and their impact on the cutoff definition and risk of VTE associated with elevated clotting factors. Factor VIII, IX, XI, and XII activities were measured in 499 blood donors and 286 patients with VTE. Age and body mass index predicted significantly and independently the clotting factor activities of factors VIII, IX, and XI, whereas use of oral contraceptives predicted factor IX, XI, and XII levels. Percentiles of clotting factor activities, which are often used for the cutoff definition of elevated clotting factors, varied due to the effect of age, body mass index, and oral contraceptives. The adjusted odds ratios for VTE were 10.3 [95% confidence interval (CI) 5.1-20.7], 6.1 (95% CI 3.1-12.0), and 3.3 (95% CI 1.9-5.8) for elevated factors VIII, IX, and XI, respectively. Furthermore, our study demonstrates for the first time that elevated factor XII is associated with an increased risk of VTE (adjusted odds ratio 2.9, 95% CI 1.6-5.3).

Coagulation and fibrinolysis are in balance after moderate exercise in middle-aged participants

Increased age is associated with a higher risk of thrombotic events. The aim of this study was to investigate the age-related changes in hemostasis before and after moderate exercise controlled by individual anaerobic threshold as recommended for rehabilitation training. In this study, 24 young (25 +/- 1 years) and 24 middle-aged healthy nonsmokers (48 +/- 1 years) underwent an individualized exercise test with 80% of individual anaerobic threshold (young individuals: 127 +/- 6 W; middle-aged individuals: 128 +/- 5 W; values are expressed as mean +/- standard error of mean) for 60 minutes. The blood samples were collected before and after the exercise. The age-related higher (P < or = .05) levels could be detected in factors II, VII, VIII, IX, XI, XII, prothrombin fragment 1+2, in tissue plasminogen activator antigen and activity, as well as in plasminogen. The relative exercise-induced increases in these parameters were similar in both groups, although beginning at a higher level for those in the middle-aged group.A statistically enhanced increase after exercise in the middle-aged group could be shown in prothrombin fragment 1+2 (young individuals: 98 +/- 6 to 102 +/- 6 pmol/L; middle-aged individuals: 138 +/- 7 to 156 +/- 8 pmol/L) and in thrombin-antithrombin complex (young individuals: 2.2 +/- 0.1 to 3.1 +/- 0.2 microg/L; middle-aged individuals: 2.4 +/- 0.3 to 3.9 +/- 0.6 microg/L); the latter only showing a tendency. The data show the age-related changes with a rise in blood coagulation and fibrinolysis in a healthy middle-aged group compared with younger participants. Moderate exercise leads to comparably relative increases in hemostatic parameters but starting at higher levels. However, the exercise-induced thrombin generation (prothrombin fragment 1+2) is enhanced in the middle-aged participants in comparison with younger participants, but may be compensated by a sufficient fibrinolysis, and therefore the hemostatic system remains in balance.

An age-related homeostasis mechanism is essential for spontaneous amelioration of hemophilia B Leyden

Regulation of age-related changes in gene expression underlies many diseases. We previously discovered the first puberty-onset gene switch, the age-related stability element (ASE)/age-related increase element (AIE)-mediated genetic mechanism for age-related gene regulation. Here, we report that this mechanism underlies the mysterious puberty-onset amelioration of abnormal bleeding seen in hemophilia B Leyden. Transgenic mice robustly mimicking the Leyden phenotype were constructed. Analysis of these animals indicated that ASE plays a central role in the puberty-onset amelioration of the disease. Human factor IX expression in these animals was reproducibly nullified by hypophysectomy, but nearly fully restored by administration of growth hormone, being consistent with the observed sex-independent recovery of factor IX expression. Ets1 was identified as the specific liver nuclear protein binding only to the functional ASE, G/CAGGAAG, and not to other Ets consensus elements. This study demonstrates the clinical relevance of the first discovered puberty-onset gene switch, the ASE/AIE-mediated regulatory mechanism.

Hemostasis and aging

Many changes in the vasculature, hemostasis and endothelium, including alterations of platelets, coagulation and fibrinolytic factors, occur during aging. While the increasing hypercoagulability observed with aging may account for the higher incidence of thrombotic cardiovascular disorders in the elderly, the lack of genetic protective factors against thrombosis in healthy centenarians suggests that little is yet known about the age-associated changes of hemostasis. The complex inter-relationships between inherited and acquired factors influencing the hemostatic system during aging are discussed in this review.

Genetic determinants of normal variation in coagulation factor (F) IX levels: genome-wide scan and examination of the FIX structural gene

BACKGROUND

High-normal and elevated plasma FIX activity (FIX:C) levels are associated with increased risk for venous- and possibly arterial-thrombosis.

OBJECTIVE

Because the broad normal range for FIX:C involves a substantial unknown genetic component, we sought to identify quantitative-trait loci (QTLs) for this medically important hemostasis trait.

METHODS

We performed a genome-wide screen and a resequencing-based variation scan of the known functional regions of every distinct FIX gene (F9) in the genetic analysis of idiopathic thrombophilia project (GAIT), a collection of 398 Spanish-Caucasians from 21 pedigrees.

RESULTS

We found no evidence for linkage (LOD scores <1.5) despite genotyping more than 540 uniformly-spaced microsatellites. We identified 27 candidate F9 polymorphisms, including three in cis-elements responsible for the increase in FIX:C that occurs with aging, but found no significant genotype-specific differences in mean FIX:C levels (P-values > or = 0.11) despite evaluating every polymorphism in GAIT by marginal multicovariate measured-genotype association analysis.

CONCLUSIONS

The heritable component of interindividual FIX:C variability likely involves a collection of QTLs with modest effects that may reside in genes other than F9. Nevertheless, because the alleles of these 27 polymorphisms exhibited a low overall degree of linkage disequilibrium, we are currently defining their haplotypes to interrogate several highly-conserved non-exonic sequences and other F9 segments not examined here.

Characterization of a monoclonal antibody B1 that recognizes phosphorylated Ser-158 in the activation peptide region of human coagulation factor IX

Blood coagulation factor IX (FIX) undergoes various post-translational modifications such as gamma-carboxylation and glycosylation. Non-phosphorylated recombinant FIX has been reported to rapidly disappear from plasma, indicating that phosphorylation of FIX plays an important role in the physiological activity of this coagulation factor. In this study, we characterized the human FIX activation peptide (AP) using a monoclonal antibody that recognizes phosphorylated Ser-158 in the AP region. Murine monoclonal antibody B1 against human FIX recognized FIX with an apparent K(d) value of 5 nm in the presence of Ca(2+) (EC(50) = 0.58 mm). B1 bound to the isolated AP of FIX and retained the Ca(2+) dependence of binding to the isolated AP. The deglycosylation of AP did not affect the binding of B1 to AP, while B1 failed to bind to recombinant AP expressed in Escherichia coli. MALDI-TOF mass spectrometry showed that the m/z of plasma-derived deglycosylated AP is 82.54 Da greater than that of recombinant AP. The binding ability of B1 to AP was lost by the dephosphorylation of plasma-derived AP. B1 bound to synthetic peptide AP-(5-19), including phosphoserine-13, but not to the non-phosphorylated AP-(5-19) in the presence of Ca(2+). These data provide direct evidence that Ser-13 of the plasma-derived FIX AP region (Ser-158 of FIX) is phosphorylated and that B1 recognizes the epitope, which includes Ca(2+)-bound phosphoserine-158. B1 should be useful in the quality control of biologically active recombinant FIX containing phosphoserine-158.

A novel gene expression system: non-viral gene transfer for hemophilia as model systems

It is highly desirable to generate tissue-specific and persistently high-level transgene expression per genomic copy from gene therapy vectors. Such vectors can reduce the cost and preparation of the vectors and reduce possible host immune responses to the vector and potential toxicity. Many gene therapy vectors have failed to produce therapeutic levels of transgene because of inefficient promoters, loss of vector or gene expression from episomal vectors, or a silencing effect of integration sites on integrating vectors. Using in vivo screening of vectors incorporating many different combinations of gene regulatory sequences, liver-specific, high-expressing vectors to accommodate factor IX, factor VIII, and other genes for effective gene transfer have been established. Persistent and high levels of factor IX and factor VIII gene expression for treating hemophilia B and A, respectively, were achieved in mouse livers using hydrodynamics-based gene transfer of naked plasmid DNA incorporating these novel gene expression systems. Some other systems to prolong or stabilize the gene expression following gene transfer are also discussed.

Myocardial fibrosis in mice with overexpression of human blood coagulation factor IX

Elevated circulatory levels of many blood coagulation factors are known to be a risk factor for deep vein thrombosis in humans. Here we report the first direct demonstration of a close association between elevated circulatory factor IX levels in mice with thrombosis as well as myocardial fibrosis. Transgenic mice overexpressing human factor IX at persistently high levels died at much younger ages than their cohorts expressing lower levels, or nontransgenic control animals. The median survival age of animals was inversely related to the circulatory levels of human factor IX. Prematurely dying animals had focal fibrotic lesions predominantly present in the left ventricular myocardium, and vasculatures in these lesions showed fibrin deposition. Thromboemboli were also present in other organs, including lung and brain. These observations support the hypothesis that persistently high circulatory levels of factor IX are a risk factor not only for thrombosis and/or thromboembolism, but also for myocardial fibrosis mimicking human myocardial infarction.

Limitation in use of heterologous reporter genes for gene promoter analysis. Silencer activity associated with the cloramphenicol acetyltransferase reporter gene

Various heterologous reporter genes have been widely used for the functional characterization of gene promoters. Many such studies often found weak to very strong silencer activities to be associated with specific parts of the basal promoter or further upstream regions. In this study, we carried out a systematic study on human blood coagulation factor IX (hFIX) and anti-coagulant protein C (hPC) genes, previously shown to have silencer activities associated with their 5'-flanking regions containing promoter sequences. With newly constructed chloramphenicol acetyltransferase (CAT) reporter vectors carrying hFIX or hPC gene promoter sequences, we confirmed the strong silencer activities associated with the regions nt -1895 through nt -416 of the hFIX gene or with the region nt -802 through nt -82 of the hPC gene. However, no such silencer activities associated with the specific regions were found when autologous hFIX cDNA, hFIX minigenes, or hPC minigenes were used as reporters in the expression vector system. Relative levels of CAT, hFIX, and hPC proteins produced in the transient assays correlated well with their mRNA levels. Human FIX minigene constructs containing a simian virus 40 (SV40) 3'-untranslated region (UTR) taken from the CAT reporter gene showed no silencer activity, indicating that SV40 3'-UTR sequence of the CAT reporter gene does not contribute to the silencer activity. Expression vectors constructed with the beta-galactosidase gene under the control of hFIX gene promoter sequences also showed no silencer activity associated with the region nt -1895 through nt -416. These findings indicate that silencer activities associated with specific regions of promoter sequences as analyzed with CAT reporter genes may represent artifacts specific to the CAT reporter genes. Our findings strongly suggest a need for re-examination of promoter characterizations of many eukaryotic genes, which have been studied to date with CAT reporter genes.

Vascular complications and gene therapy

For gene therapy, the last few years have been an exciting period. Encouraging results from several successful gene therapy trials were reported. Children born with a life-threatening immune system disorder, severe combined immune deficiency (SCID), were cured after receiving gene therapy for replacement of their defective adenosine deaminase (ADA) gene. Gene therapy successes related to vascular complications were also reported. The first human gene therapy trial for a blood-vessel disorder was performed successfully, in which copies of an angiogenic gene, the vascular endothelial growth factor (VEGF) gene, were directly delivered to the area surrounding the diseased artery of the leg of a patient with peripheral artery disease. Within a few days, this stimulated the growth of new blood vessels around the blockage in the ailing blood vessel and helped avoid amputation. In 1998, a patient with genetically small arteries became the first to receive VEGF gene therapy in the heart. Multiple copies of a plasmid with the VEGF gene were delivered into the damaged area of the heart, and a few days later angiogenesis ensued that helped bypass the blocked vessel, with markedly reduced chest pain in the patient. Gene therapy is becoming a reality and, more importantly, it appears to be safe and does not require supplementary immuno-suppressing drugs. Gene therapy seems to have begun delivering on its promises.

Aging accelerates endotoxin-induced thrombosis : increased responses of plasminogen activator inhibitor-1 and lipopolysaccharide signaling with aging

Although older subjects are susceptible to thrombosis under septic conditions, the underlying molecular mechanisms have not been fully elucidated. Since elevated plasminogen activator inhibitor-1 (PAI-1) primarily contributes to endotoxin-induced thrombosis, we first compared the induction of PAI-1 by lipopolysaccharide (LPS) between young and aged mice. The higher induction of PAI-1 antigen and mRNA with increased renal glomerular fibrin deposition was observed in LPS-treated aged mice compared to young mice. In situ hybridization analysis showed that the aging-associated induction of PAI-1 mRNA by LPS was pronounced in hepatocytes and in renal glomerular cells. The increased magnitude of the response of aged mice to lower doses of LPS was observed in terms of renal glomerular fibrin deposition and PAI-1 mRNA induction in the tissues. Furthermore, older PAI-1 deficient mice treated with LPS developed much less fibrin deposition in kidneys. Importantly, a larger induction of receptor molecules for LPS (eg, CD14 and Toll-like receptor 4) was demonstrated in LPS-treated aged mice as compared with young mice. The enhanced LPS signaling in aged mice was also demonstrated by the marked induction of nuclear factor-kappaB in the tissues after endotoxin treatment. As a consequence, increases in an inflammatory cytokine, tumor necrosis factor-alpha, were pronounced in plasma and tissues of LPS-treated aged mice. These results emphasize the key role played by PAI-1 in aging-associated deterioration in this thrombosis model, and suggest that the hyperresponse of PAI-1 gene to LPS results from the enhanced LPS signaling and the subsequent inflammatory response in aged mice.

Setting a trap for aging-related genes in Drosophila

In the October 2002 issue of Aging Cell, Seroude et al. used an enhancer trap technique to identify Drosophila genes whose expression changes with age. In this Perspective, the author discusses the implications of these results, including the possibility of using the enhancer trap lines to identify biomarkers of aging.

Genetic mechanisms of age regulation of protein C and blood coagulation

Blood coagulation activity in humans increases with age. We previously identified two genetic elements, age-related stability element (ASE; GAGGAAG) and age-related increase element (AIE; unique stretch of dinucleotide repeats), which were responsible for age-related stable and increasing expression patterns, respectively, and together recapitulated normal age regulation of the human factor IX (hFIX) gene. Here we report the age-regulatory mechanisms of human anticoagulant protein C (hPC), which shows an age-stable pattern of circulatory levels. The murine protein C gene showed an age-related stable expression pattern in general agreement with that of the hPC. Through longitudinal analyses of transgenic mice carrying hPC minigenes, the hPC gene was found to have a functional age-related stability element (hPC ASE; CAGGAAG) in the 5'-upstream proximal region but was found to lack any age-related increase element. Three other ASE-like sequences present in the hPC gene, GAGGAAA and (G/C)AGGATG, also bound nuclear proteins but were not active in the age regulation of the hPC gene. Functional hPC ASE and hFIX ASE were apparently generated through convergent evolution, and hFIX ASE can fully substitute for the hPC ASE in conferring age-related stable expression pattern of the hPC gene. In the presence of the hPC ASE, hFIX AIE can convert the age-stable expression pattern of the hPC gene to a hFIX-like age-related increase pattern. These results support the universality of ASE and AIE functions across different genes. Clearance of hPC protein from the circulation was not significantly affected by age. We now have established the basic mechanisms responsible for the age-related increase of blood coagulation activity.

Biology of mammalian L1 retrotransposons

L1 retrotransposons comprise 17% of the human genome. Although most L1s are inactive, some elements remain capable of retrotransposition. L1 elements have a long evolutionary history dating to the beginnings of eukaryotic existence. Although many aspects of their retrotransposition mechanism remain poorly understood, they likely integrate into genomic DNA by a process called target primed reverse transcription. L1s have shaped mammalian genomes through a number of mechanisms. First, they have greatly expanded the genome both by their own retrotransposition and by providing the machinery necessary for the retrotransposition of other mobile elements, such as Alus. Second, they have shuffled non-L1 sequence throughout the genome by a process termed transduction. Third, they have affected gene expression by a number of mechanisms. For instance, they occasionally insert into genes and cause disease both in humans and in mice. L1 elements have proven useful as phylogenetic markers and may find other practical applications in gene discovery following insertional mutagenesis in mice and in the delivery of therapeutic genes.

Midkine and cyclooxygenase-2 promoters are promising for adenoviral vector gene delivery of pancreatic carcinoma

Midkine (MK), a heparin binding growth factor, and cyclooxygenase-2 (COX-2), a key enzyme in the conversion of arachidonic acid to prostaglandin, are both up-regulated at the mRNA or protein level in many human malignant tumors. Here, we investigated the tumor specificity of both MK and COX-2 promoters in human pancreatic cancer, with the aim to improve the selectivity of therapeutic gene expression. We constructed recombinant adenoviral (Ad) vectors containing either the luciferase (Luc) reporter gene under the control of the COX-2 or MK promoter or the herpes simplex virus thymidine kinase (HSV Tk) gene under the control of the COX-2 promoter and compared the expression with the cytomegalovirus (CMV) promoter. AdMKLuc achieved moderate to relatively high activity upon infection to both primary and established pancreatic carcinoma cells. Of the two COX-2 promoter regions (COX-2M and COX-2L), both revealed a high activity in primary pancreatic carcinoma cells, whereas in the established pancreatic carcinoma cell lines, COX-2L has an approximately equal high activity compared to CMV. In addition, both AdCOX-2M Tk and AdCOX-2L Tk induced marked cell death in response to ganciclovir (GCV) in three of four established pancreatic carcinoma cell lines. From these results, and because it has been reported that AdMKTk and AdCOX-2L Tk in combination with GCV did not reveal significant liver toxicity, we conclude that the MK as well as the COX-2 promoters are promising tumor-specific promoters for Ad vector-based gene therapy of pancreatic cancer.

Characterization of the cyclooxygenase-2 promoter in an adenoviral vector and its application for the mitigation of toxicity in suicide gene therapy of gastrointestinal cancers

The application of adenoviral molecular chemotherapy for systemic malignant disease using herpes simplex virus thymidine kinase has been limited by ectopic transgene expression in the liver due to the vector hepatotropism. The aim of this study was to mitigate this hepatotoxicity using the promoter of cyclooxygenase-2, inactive in liver but active in many gastrointestinal cancers. To analyze the specificity of transgene expression driven by cyclooxygenase-2 (cox-2) promoters, promoters of two different lengths were incorporated into adenoviral vectors to drive luciferase expression. The specific cytocidal effect and in vivo toxicity were analyzed with thymidine kinase expression vectors. The specificity of the cox-2 promoter was well preserved in the adenoviral vector. In vivo, the cox-2 promoter (-1432/+59) showed very little activity in the liver but attained high activity, comparable to that of the cytomegalovirus promoter, in cyclooxygenase-2-positive subcutaneous tumors. The cox-2 promoter-driven thymidine kinase-expressing vectors showed a cytocidal effect specifically in cyclooxygenase-2-positive cells. When mice were treated with the thymidine kinase-expressing vector and ganciclovir, the cox-2 promoter successfully mitigated the fatal hepatotoxicity, which was observed with the cytomegalovirus promoter-driven vector. The cox-2 promoter successfully mitigated the adverse effects of adenoviral suicide gene therapy by minimizing transgene expression in the liver.

Carrier analysis of a moderately affected haemophilia B family

Here we report the successful genetic diagnosis of a pregnant caucasian female patient whose family has a history of moderate haemophilia B. While restriction fragment length polymorphism (RFLP) analysis was not informative, nucleotide sequencing of the factor IX genes of the patient's family members determined that her mother and one of her two sisters were carriers of the mutation C31008T, which causes a Thr296Met transition. In contrast, the pregnant female herself and her other sister were found to carry only normal alleles. Plasma factor IX activity and antigen levels supported these findings.

Inclusion of the hepatic locus control region, an intron, and untranslated region increases and stabilizes hepatic factor IX gene expression in vivo but not in vitro

We systematically compared human factor IX gene expression from a variety of plasmids containing different cis-regulatory sequences after transfection into different hepatocyte cell lines, or in vivo, after their injection into the livers of mice. Although there was a 1.5- to 2.0-fold variation in gene expression from cultured cells, a 65-fold variation was observed in the in vivo studies. We found that a plasmid containing the apolipoprotein E locus control region (HCR), human alpha1-antitrypsin (hAAT) promoter, hFIX minigene (hFIXmg) sequence including a portion of the first intron (intron A), 3'-untranslated region (3'-UTR), and a bovine growth hormone polyadenylation signal (bpA) produced the highest serum level of human factor IX, reaching 18 microg/ml (normal = 5 microg/ml) 1 day after injection. Although most of the plasmid DNAs resulted in transient gene expression, inclusion of an intron, a polyadenylation signal from either the 1.7-kb 3'-UTR or the 0.3-kb bpA, and the HCR resulted in persistent and therapeutic levels of hFIX gene expression, ranging from 0.5 to 2 microg/ml (10 to 40% of normal) for 225 days (length of experiment). These data underscore the importance of cis sequences for enhancing in vivo hepatic gene expression and reemphasize the lack of correlation of gene expression in tissue culture and in vivo studies.

Genetic mechanisms of age regulation of blood coagulation: factor IX model

Blood coagulation capacity increases with age in healthy individuals, apparently because of increases in the plasma concentration of most procoagulant factors. This phenomenon may play an important role in the advancing age-associated increase of cardiovascular diseases and thrombosis. Through longitudinal analyses of transgenic mice, we recently identified 2 critical age-regulatory elements, AE5' and AE3', which are together essential for age regulation of the normal human factor IX (hFIX) gene. AE5', present in the long interspersed repetitive element-derived sequence of the 5' upstream region, containing polyomavirus enhancer activator-3 or a closely related element, is responsible for age-stable expression of the gene and functions in a position-independent manner. AE3', present in the middle of the 3' untranslated region, is responsible for age-associated elevation of hFIX mRNA levels in the liver. Presence of both AE5' and AE3' is needed to recapitulate normal age regulation of the hFIX gene. Because factor IX clearance from the circulation is not significantly affected by age, age regulation of hFIX levels is achieved primarily by a combination of stabilization of gene transcription and age-dependent increases in the mRNA levels, which are presumably due to increasing mRNA stabilization. The stage is now set for further systematic studies of the genetic and molecular mechanisms of age regulation of other key coagulation and anticoagulation factors in hopes of understanding the overall age regulation of blood coagulation.

Congenital Hemorrhagic Disorders: New Insights into the Pathophysiology and Treatment of Hemophilia

The diagnostic and treatment strategies related to hemophilia are rapidly evolving. This article focuses on some of the issues of importance. Diagnostic advances in molecular genetics are reviewed by Dr. Ginsburg in Section I, including the current state of knowledge regarding the mutations responsible for hemophilia, with reference to the potential clinical applications of DNA diagnosis and prenatal testing.

Within the area of new therapeutic approaches in hemophilia, recombinant factor VIII and factor IX concentrates, their use and availability are addressed by Dr. Lusher in Section II as well as the use of so-called “primary prophylaxis” with the aim of decreasing long-term hemophilia athropathy. The use of radionuclide synovectomy as replacement for more invasive methods is also reviewed.

Various approaches to the ongoing challenge of the management of hemophilia patients with inhibitors against factor VIII and factor IX are reviewed by Dr. Hedner in Section III, including the principles for immune tolerance induction and the use of recombinant factor VIIa to induce hemostasis in bleeding patients with inhibitors.

In Section IV, gene therapy in hemophilia is reviewed by Dr. High, who focuses on recent developments in the rapidly moving field of gene therapy for hemophilia. Three phase I trials of gene therapy for hemophilia were initiated in 1999, and additional proposed trials are currently in the regulatory review process. Certain aspects of the pathophysiology of hemophilia make it an attractive model for a gene-based approach to treatment. These include latitude in choice of target tissue, a wide therapeutic window, the availability of small and large animal models of the disease, and the ease of determining therapeutic efficacy. Since there is very little published information regarding the ongoing trials, this section reviews the approaches being used, the published pre-clinical data, and considerations affecting clinical trial design in hemophilia gene therapy.

Congenital Hemorrhagic Disorders: New Insights into the Pathophysiology and Treatment of Hemophilia

The diagnostic and treatment strategies related to hemophilia are rapidly evolving. This article focuses on some of the issues of importance. Diagnostic advances in molecular genetics are reviewed by Dr. Ginsburg in Section I, including the current state of knowledge regarding the mutations responsible for hemophilia, with reference to the potential clinical applications of DNA diagnosis and prenatal testing.

Within the area of new therapeutic approaches in hemophilia, recombinant factor VIII and factor IX concentrates, their use and availability are addressed by Dr. Lusher in Section II as well as the use of so-called “primary prophylaxis” with the aim of decreasing long-term hemophilia athropathy. The use of radionuclide synovectomy as replacement for more invasive methods is also reviewed.

Various approaches to the ongoing challenge of the management of hemophilia patients with inhibitors against factor VIII and factor IX are reviewed by Dr. Hedner in Section III, including the principles for immune tolerance induction and the use of recombinant factor VIIa to induce hemostasis in bleeding patients with inhibitors.

In Section IV, gene therapy in hemophilia is reviewed by Dr. High, who focuses on recent developments in the rapidly moving field of gene therapy for hemophilia. Three phase I trials of gene therapy for hemophilia were initiated in 1999, and additional proposed trials are currently in the regulatory review process. Certain aspects of the pathophysiology of hemophilia make it an attractive model for a gene-based approach to treatment. These include latitude in choice of target tissue, a wide therapeutic window, the availability of small and large animal models of the disease, and the ease of determining therapeutic efficacy. Since there is very little published information regarding the ongoing trials, this section reviews the approaches being used, the published pre-clinical data, and considerations affecting clinical trial design in hemophilia gene therapy.