Biomedical subjects

K Okamoto

Publications and source records attributed to K Okamoto.

At least 217 records · Page 12Linked to original sources

PubMed2000

Serum midkine levels are increased in patients with various types of carcinomas.

The level of expression of midkine (MK), a heparin-binding growth factor, is increased in many types of human carcinomas. An enzyme-linked immunoassay, which utilizes a combination of rabbit and chicken antibodies revealed that serum MK level in the controls (n = 135) was 0.154 +/- 0.076 (mean +/- SD) ng ml(-1)with an apparent cut-off value as 0.5 ng ml(-1). Serum MK level was significantly elevated in the cancer patients (n = 150) (P< 0.001); 87% of the patients showed levels of more than 0.5 ng ml(-1). All ten types of cancer examined showed a similar profile of serum MK level. There was no or weak correlation between C-reactive protein level, a marker of inflammation, and serum MK level. Furthermore, in case of gastric carcinoma and lung carcinoma, patients with stage I carcinoma already showed elevated serum MK levels. The present results indicated that serum MK could serve as a general tumour marker with a good potential for clinical application.

Adult↗

PubMed2000

Ribozyme-mediated inactivation of mutant K-ras oncogene in a colon cancer cell line.

Mutation of c-K-ras oncogene is an important step in progression of colon cancer. We used a hammerhead ribozyme (KrasRz) against mutated K-ras gene transcripts (codon 12, GTT) to inactivate mutant K-ras function in the colon cancer cell line SW480, harbouring a mutant K-ras gene. The beta-actin promoter-driven KrasRz sequence (pHbeta/KrasRz) was introduced into these cells (SW480/KrasRz), and we evaluated its effects on growth of the colon cancer. The gene expression of angiogenesis-related molecules (vascular endothelial growth factor and thrombospondin) was also estimated in SW480/KrasRz. KrasRz specifically and efficiently cleaved the mutant K-ras mRNA but not wild-type mRNA in vitro. SW480/KrasRz showed decreased growth rate under tissue culture conditions (P< 0.01, Dunnett's test). The xenotransplantability of SW480/KrasRz (XeSW480/KrasRz) was significantly decreased in nude mice (P< 0.05, Fisher's exact test). Tumour volume of the xenografts XeSW480/KrasRz was significantly smaller than that of XeSW480/DisKrasRz (P< 0.01, Dunnett's test). Gene expression of VEGF was suppressed in SW480/KrasRz, while TSP1 gene expression was enhanced. The SW480/KrasRz cells showed apoptosis-related features including nuclear condensation and DNA fragmentation. These results suggested that the hammerhead ribozyme-mediated inactivation of the mutated K-ras mRNA induced growth suppression, apoptosis and alteration of angiogenic factor expression.

Animals↗

PubMed2000

Neutrophils express tissue factor in a monkey model of sepsis.

BACKGROUND: Although tissue factor (TF) is involved in hemostasis, thrombogenesis, inflammation, and cellular immune response, its source in sepsis remains controversial. Recently, we found that, in addition to monocytes and endothelial cells, neutrophils may express TF in a rabbit model. The purpose of this study was to determine whether neutrophils could be a source of TF in a monkey model of sepsis. METHODS: TF messenger RNA (mRNA) and protein in neutrophils were assayed by in situ hybridization and immunohistochemistry in tissues obtained from monkeys after injection of lipopolysaccharide (LPS) (n = 3) and after injection of saline as a control (n = 2). Coagulation parameters were measured before and at 1.5 and 3 hours after injections. RESULTS: In LPS-treated monkeys, TF mRNA and protein were induced not only in monocytes and endothelial cells, but also in neutrophils accumulating in the liver 3 hours after LPS injection. Thrombin-antithrombin III complex and fibrin degradation products D-dimer levels were significantly increased at 3 and 1.5 hours after LPS injection compared with controls. CONCLUSIONS: Neutrophils are a source of TF and are implicated in direct activation of the coagulation cascade in the early phases of sepsis in the monkey. These results give important information for the treatment of sepsis.

Animals↗

PubMed2000

Pharmacologic effect of recombinant human IFN-alpha, continuously released from a matrix prepared from a polyglycerol ester of fatty acids, on 2',5'-oligoadenylate synthetase activity in murine liver.

The objective of this study was to assess the pharmacologic effect of continuously released recombinant human interferon-alpha (rHuIFN-alpha) in the liver, the target organ of chronic hepatitis B and C, using 2',5'-oligoadenylate synthetase (2',5'-OAS) activity as an indicator of an antiviral state. A cylindrical matrix prepared from tetraglycerol dipalmitate (TGDP), a polyglycerol ester of fatty acids (PGEF), released rHuIFN-alpha in a pseudo-zero-order manner for about 1 week after implantation into mice, without any major loss of rHuIFN-alpha biologic activity during the release period. To evaluate the pharmacologic effect of the rHuIFN-alpha continuously released from this type of matrix, we established a murine test system. Bolus injections of rHuIFN-alpha solution at three doses increased 2',5'-OAS activities in murine liver extract and serum in a dose-dependent manner, indicating that this system is suitable for evaluating rHuIFN-alpha activity. After subcutaneous insertion of TGDP-matrix implants containing 5.5x10(7) IU rHuIFN-alpha per animal, 2',5'-OAS activities in both liver extracts and serum increased rapidly and remained high for over 1 week. Subcutaneous injections of an equivalent total dose (5.0x10(7) IU/animal per week) of rHuIFN-alpha solution in three or seven fractions prolonged 2',5'-OAS activities compared with a single bolus injection. Comparing 2',5'-OAS activity on day 7 and the portion of the area under the 2',5'-OAS activity-time curve above the normal level (deltaAUC) between the TGDP-matrix implant and multiple injections of the solution revealed that continuously released rHuIFN-alpha has an effect almost equivalent to that of three or seven injections of the solution per week.

2',5'-Oligoadenylate Synthetase↗

PubMed2000

Respiratory-related quality of life: relation to pulmonary function, functional exercise capacity, and sputum biophysical properties.

One of the difficulties in assessing mucoactive therapy is selecting clinical outcome variables that reflect the impact of clearing airway secretions on quality of life (QOL). Petty and colleagues developed a questionnaire designed to evaluate the clinical impact of mucoactive therapy in patients with chronic bronchitis (CB). We evaluated this questionnaire in a multicenter study of a mucolytic medication used in patients with CB and hypothesized that spirometry, exercise capacity, and sputum clearability changes would correlate with QOL changes. This was a multicenter trial in 159 patients with stable CB (111 completed the 16-week study). Spirometry, plethysmography, the 6-minute walk test (6MWT), and Petty score as a measure of QOL were assessed at each visit. Sputum was collected at each visit. Cough transportability was measured in a cough machine, and mucociliary transportability was measured on the frog palate. Cohesivity was measured in a filancemeter, interfacial tension by de Noüy ring, and wettability by contact angle analysis. Within the entire data set of 694 evaluations, there was no correlation between pulmonary function and QOL. There was an inverse correlation with distance covered in a 6MWT (R(2) = 0.041, p < 0.0001). Sputum CTR was directly correlated with QOL (R(2) = 0.027, p < 0.0001). Change from baseline (mean of first three visits) was computed and compared the change in the mean of values at the 8- and 12-week visits (n = 108 sets of data pairs). This was analyzed as a percentage of change for continuous measurements, and as QOL is normative, we calculated the absolute change in QOL. There was no relation between QOL and 6MWT changes. There was an inverse relation between change in forced expiratory volume in 1 second and QOL (R(2) = 0.092, p = 0.0021) as well as between forced vital capacity and QOL (R(2) = 0.05, p = 0.024). There was a direct relation between CTR and QOL (R(2) = 0.039, p = 0.048). The relation between QOL and 6-minute walk distance was expected but weak. The consistent relation between CTR and QOL (suggesting that improved CTR of sputum is associated with decreased QOL) is difficult to explain. A change in forced expiratory volume in 1 second and forced vital capacity did correlate with a change in QOL. There is a need for a good QOL tool to evaluate mucus clearance devices or medications. The Petty questionnaire was designed specifically for this task, but the effect on sputum properties by current mucoactive agents may be too small to elicit a significant change in the Petty score.

Analysis of Variance↗

PubMed2000

Sequence motif-specific assignment of two [2Fe-2S] clusters in rat xanthine oxidoreductase studied by site-directed mutagenesis.

The sequence motif-specific assignment of the two distinct [2Fe-2S] clusters in rat xanthine oxidoreductase (XOR) was unequivocally established by site-directed mutagenesis of recombinant enzymes expressed in a baculovirus-insect cell system and electron paramagnetic resonance (EPR) spectroscopy. The conserved cysteine residues, including Cys-115, in the unusual C-terminal -Cys-Xaa(2)-Cys-//-Cys-Xaa(1)-Cys- motif serve as ligands to the Fe/S I center, which is probably located in close proximity to the Mo-pterin center. Other conserved cysteine residues, including Cys-43 and Cys-51, in the N-terminal plant ferredoxin-like motif serve as ligands to the Fe/S II center, which is distantly located from the Mo-pterin center. The present sequence motif-specific assignment of the Fe/S I and II centers is discussed in the light of the structural features of XOR.

Amino Acid Sequence↗

PubMed2000

Porphyromonas gingivalis proteinases as virulence determinants in progression of periodontal diseases.

Porphyromonas gingivalis, one of the major causative agents of periodontal diseases, produces large amounts of arginine- and lysine-specific cysteine proteinases in cell-associated and secretory forms, which are now referred to as Arg-gingipain (Rgp) and Lys-gingipain (Kgp), respectively. A number of studies have revealed that these proteinases are closely associated with the periodontopathogenesis of this bacterium: destruction of periodontal connective tissues, disruption of host defense mechanisms, and development and maintenance of inflammation in periodontal pockets. With respect to the physiology of the bacterium, Rgp and Kgp are indispensable for it to obtain nutrients from the environment, since it cannot utilize saccharides as carbon/energy sources for growth and totally depends on peptides and amino acids that are provided from environmental proteins by Rgp and Kgp. Furthermore, proteolytic activities of Rgp and Kgp contribute to processing/maturation of various cell-surface proteins of P. gingivalis, such as fimA fimbrilin (a subunit of major fimbriae), 75-kDa protein (a subunit of minor fimbriae), hemagglutinins, and the hemoglobin receptor protein, which are important for the bacterium to colonize and proliferate in the gingival crevice and to invade the periodontium. These findings strongly indicate critical roles of Rgp and Kgp in the virulence of P. gingivalis.

Adhesins, Bacterial↗

PubMed2000

Design and synthesis of sensitive fluorogenic substrates specific for Lys-gingipain.

Lys-gingipain (Kgp) is a major cysteine proteinase produced by the oral anaerobic bacterium Porphyromonas gingivalis, and has been implicated as a major pathogen in the development and progression of advanced adult periodontitis. This enzyme is believed to act as a major virulence factor of the disease, yet there exist no convenient and sensitive substrates for analyzing its biological activity. For a better understanding of the importance of this enzyme in the organism, there is an urgent need for specific substrates. Here we designed and synthesized two peptide 4-methyl-coumaryl-7-amides (MCA), carbobenzoxy (Z)-His-Glu-Lys-MCA, and Z-Glu-Lys-MCA, and tested their possible use as sensitive substrates for Kgp with limited specificity. Both substrates exhibited greater k(cat)/K(m) values than the best known Kgp substrates described so far. Both substrates were resistant to Arg-gingipain, another pathogenic cysteine proteinase from P. gingivalis, as well as trypsin and cathepsins B, L, and H. The levels of Kgp in various microorganisms and human cells were determined with Z-His-Glu-Lys-MCA. Little or no Kgp-like activity was detected in either other microorganisms or human cells tested. These results indicate that the present substrates are a valuable and fast tool for routine assays and for mechanistic studies on Kgp.

Adhesins, Bacterial↗

PubMed2000

Fas-associated death domain protein is a Fas-mediated apoptosis modulator in synoviocytes.

OBJECTIVE: To understand the intracellular regulatory mechanisms in Fas-mediated apoptosis of synoviocytes, we examined the involvement of caspases [caspase-1/ICE (interleukin-1beta converting enzyme), caspase-3/CPP32, and caspase-8/FLICE] and Fas-associated death domain protein (FADD) forming a death-inducing signalling complex (DISC) in Fas-mediated apoptosis of synoviocytes. METHODS: Synoviocytes were obtained from rheumatoid arthritis (RA) and osteoarthritis (OA) patients. The number of dead cells was counted after treatment with anti-Fas monoclonal antibody in the presence of caspase-1-, -3-, or -8-specific inhibitors. The involvement of caspases and FADD in Fas-mediated apoptosis of RA synoviocytes was examined by immunoblot and immunoprecipitation analyses. RESULTS: RA synoviocytes expressed high levels of caspase-3, caspase-8, and FADD compared with OA synoviocytes. Interestingly, Fas ligation activated caspase-8 and caspase-3 with the cleavage of poly(ADP-ribose) polymerase (PARP), corresponding to apoptosis of RA synoviocytes. Furthermore, specific inhibitors for caspase-3 and caspase-8 but not caspase-1 suppressed Fas-induced apoptosis of RA synoviocytes in a dose- and time-dependent manner. Caspase-8-specific inhibitor suppressed the activation of caspase-3 after Fas ligation on RA synoviocytes. Importantly, FADD was selectively recruited to the Fas death domain during Fas-mediated apoptosis of RA synoviocytes, consistent with sensitivity to the Fas-mediated apoptosis. CONCLUSION: Our findings suggest that Fas-mediated apoptosis in synoviocytes may be regulated at the level of recruitment of FADD to the DISC, subsequently leading to the activation of the FADD/caspase-8/caspase-3 signalling pathway.

Adaptor Proteins, Signal Transducing↗

PubMed2000

Role of interleukin-10 on hyporesponsiveness of endotoxin during surgery.

OBJECTIVE: To examine whether surgical stress causes blood cells to lose their responsiveness to endotoxin during surgery. DESIGN: Prospective case series. SETTING: A university hospital. PATIENTS: Sixteen volunteers classified as American Society of Anesthesiologists physical status I-II who were scheduled for elective distal partial gastrectomy. INTERVENTIONS: We studied nine patients who underwent elective distal partial gastrectomy. Blood samples for tumor necrosis factor (TNF) and interleukin (IL)-10 assay were obtained before anesthesia, preincision, 2 hrs and 4 hrs postincision, postextubation, and 24 hrs postincision. The rest of each blood sample was diluted with 5 volumes of endotoxin-free saline, incubated for 4 hrs in the presence of lipopolysaccharide (LPS), centrifuged to remove cells, and assayed for TNF. In another seven patients, antihuman IL-10 antibody was added into the diluted whole blood sample before LPS stimulation. MEASUREMENTS AND MAIN RESULTS: TNF activity was not detected in the blood of any patient throughout the study. In contrast, plasma cortisol and IL-10 levels increased rapidly during surgery (p < .01, p < .05, respectively). LPS-induced TNF activity in whole blood decreased significantly during surgery (p < .01) and recovered to control levels by 24 hrs postincision. The peak suppression of LPS-induced TNF and the peak value of plasma IL-10 levels occurred postextubation. Treatment with anti-IL-10 antibody partially restored the ability of LPS to induce TNF activity postextubation (p < .05). CONCLUSIONS: Surgical trauma rapidly induces a transient hyporesponsiveness of blood cells to endotoxin. Plasma IL-10, which increases during surgery, participates in this hyporesponsiveness.

Adult↗

PubMed2000

Relationship between plasma cytokine concentration and multiple organ failure in patients with acute pancreatitis.

The dynamic aspects of circulating cytokines and cytokine modulators and their relationship with development of multiple organ failure (MOF) in patients with acute pancreatitis were analyzed. All cytokine and C-reactive protein levels in the circulation were higher than those in the MOF group. In particular, plasma concentrations of soluble tumor necrosis factor receptors (sTNF-RI and sTNF-RII) were significantly higher in patients with MOF than in those without even at admission. Furthermore, plasma concentrations of sTNF-Rs and interleukin-1 (IL-1) receptor antagonist (IL-1ra) were much higher than those of their counterparts, TNFalpha and IL-beta, respectively. These results suggest that the plasma concentrations of sTNF-Rs are useful predictors for the development of MOF, and actions of TNF-alpha and IL-1beta could be regulated by their modulators (soluble receptor and receptor antagonist, respectively) in the pathologic condition of severe acute pancreatitis.

Acute Disease↗

PubMed2000

Purification, crystallization and preliminary X-ray diffraction studies of xanthine dehydrogenase and xanthine oxidase isolated from bovine milk.

Xanthine dehydrogenase catalyzes the oxidation of hypoxanthine to xanthine and the further oxidation of xanthine to uric acid. The enzyme is the target of the anti-gout drug allopurinol and its involvement in postischemic reperfusion injury is presently being defined. Each subunit of the homodimeric 290 kDa enzyme contains four cofactors: one Mo-pterin, two [2Fe-2S] clusters and one FAD. Both the dehydrogenase (XDH) and the proteolytically modified oxidase form (XO) of the enzyme from bovine milk have been crystallized. XO crystals belong to space group C222(1), with unit-cell parameters a = 116.3, b = 164.4, c = 153.2 A at room temperature and a = 117.8, b = 165.4, c = 154.5 A when flash-frozen. They allow data collection to 3.3 and 2.5 A, respectively. In addition, a data set was collected from frozen XDH crystals and processed to 2.1 A. These crystals belong to space group C2, with unit-cell parameters a = 169.9, b = 124.8, c = 148.6 A, beta = 90.9 degrees. The unit-cell volumes and Matthews parameters are similar for the two crystal forms. There is one monomer per asymmetric unit in the XO crystals and a complete native dimer per asymmetric unit in the XDH crystals.

Animals↗

PubMed2000

Mutation of aromatic amino acid residues located at the amino- and carboxy-termini of Escherichia coli heat-stable enterotoxin Ip reduces the efficiency of the toxin to cross the outer membrane.

Heat-stable enterotoxin Ip (STIp) of Escherichia coli is synthesized as a precursor form consisting of pre- (amino acid residues 1 to 19), pro- (amino acid residues 20 to 54) and mature (amino acid residues 55 to 72) regions. Mature STIp (bioactive STIp) is formed in the periplasmic space after the precursor is proteolytically processed and the mature STIp translocates across the outer membrane through the secretory system including TolC, an outer membrane protein of E. coli. However, it remains unknown how the mature STIp is recognized by this secretory system. In this study, we investigated the amino acid residues of STIp involved in its translocation across the outer membrane. We prepared mutant STIp genes by site-directed mutagenesis and analyzed translocation of the mutant STIps across the outer membrane. Deletion of the Phe or Tyr residue at position 3 or 18, respectively, decreased the efficiency of translocation of STIp across the outer membrane. To confirm the involvement of these amino acid residues, we further mutated the codons for these amino acid residues to that for Gly. These mutations also decreased the efficiency of extracellular secretion of STIp. In contrast, substitution of Phe-3 and Syr-18 with Tyr and Phe, respectively, did not affect the efficiency of translocation of the toxin. These results indicated that the aromatic amino acid residues at positions 3 and 18 in the mature region are important for the ability of STIp to cross the outer membrane.

Amino Acid Substitution↗

PubMed2000

Production of serine protease of Aeromonas sobria is controlled by the protein encoded by the gene lying adjacent to the 3' end of the protease gene.

We cloned a protease gene of Aeromonas sobria and determined its nucleotide sequence. The protease is composed of 624 amino acid residues and its calculated molecular weight is 66,737.7. The amino acid sequence showed the characteristic features of a bacterial serine protease. We expressed the protease gene in Vibrio parahaemolyticus from which the synthesized protease is secreted into the culture medium as the mature form, and purified the mature protease by successive column chromatographies. The size of the mature protease is 65,000 daltons and the amino acid sequence analysis revealed that a 24-amino acid peptide at the amino terminal of the precursor is removed from the mature protease. This peptide might function as a signal peptide in translocation across the inner membrane. Subsequently, we found that the protein, designated ORF2 protein, encoded by the gene lying adjacent to the 3' end of the protease gene plays an important role in production of the protease. Mutation of the ORF2 gene did not affect transcription of the protease gene, but resulted in degradation of the protease in the cell. This shows that ORF2 protein is required for the successful production of the serine protease by cell.

Aeromonas↗

PubMed2000

Vitamin K contents in liver tissue of hepatocellular carcinoma patients.

Serum protein induced in vitamin K absence-II (PIVKA-II) is used as a tumor marker because it increases at a notably higher rate in patients with hepatocellular carcinoma. To clarify the mechanism causing the elevation of serum PIVKA-II, we measured the contents of vitamins K1 (phylloquinone, PK) and K2 (menaquinone, MK) (MK-4, MK-5, MK-6, MK-7, MK-8, MK-9, MK-10) in liver tissue resected from 21 hepatic cancer patients (12 patients with hepatocellular carcinoma and 9 patients with metastatic hepatic cancer), using HPLC combined with coulometric reduction and fluorometric detection. In the cancerous tissue of hepatocellular carcinoma patients, PK, MK-7, MK-8, and MK-10 were significantly lower than that found in the noncancerous tissue. Furthermore, MK-6, MK-7, MK-8, and MK-10 in the cancerous tissue of hepatocellular carcinoma patients were significantly lower than that in the cancerous tissue of metastatic hepatic cancer patients. These data suggested that one of the mechanisms of the elevation of serum PIVKA-II levels in hepatocellular carcinoma patients is a vitamin K deficiency in the local cancerous tissue.

Aged↗

PubMed2000

Production of a single-chain variable fragment antibody recognizing type III mutant epidermal growth factor receptor.

The type III deletion mutant of the epidermal growth factor receptor (EGFR) is a potential target in diagnostic and therapeutic approaches for those glioblastomas characterized by its expression. We previously raised a mouse monoclonal antibody, 3C10 (IgG2b) specifically recognizing this mutant EGFR. In this study, a single-chain variable fragment (scFv) antibody was produced. Partial determination of its N-terminal amino acid sequence and preparation of adequate primers for variable heavy chain (V(H)) and variable light chain (V(L)) genes were performed to allow cloning by means of reverse transcriptase-polymerase chain reaction. The genes cloned were assembled with a linker, (Gly4Ser)3, and ligated into a bacterial expression vector to express the scFv as cytoplasmic inclusion bodies. After appropriate refolding, the antibody activity of the V(H)-V(L) scFv was examined in an enzyme-linked immunosorbent assay. 3C10 scFv showed a selective reactivity with the mutant peptide, similarly to the parental 3C10 antibody. A mouse transfectant expressing the type III mutant EGFR and a glioblastoma with type III deletion-mutant EGFR were positively stained by immunofluorescence. By Biacore analysis, the affinity (K(A)) of the parental 3C10 for the mutant peptide was 9.7 x 10(7) M(-1), while that of 3C10 scFv was 2.45 - 2.48 x 10(7) M(-1), being approximately 4-fold weaker. The results together suggested that the scFv antibody retained the appropriate structure to recognize a conformational epitope of the mutant receptor, similarly to the parental antibody.

3T3 Cells↗

PubMed2000

Prevention of vaginal shortening following radical hysterectomy.

We describe a surgical procedure and post-operative management for the prevention of vaginal shortening following radical hysterectomy. A total of 452 patients who underwent hysterectomies were examined prospectively depending on the operation method. This study showed that our procedure was effective in the prevention of vaginal shortening following radical hysterectomy. Preservation of the ovaries appeared to be important in preventing vaginal shortening, and post-operative hormone replacement therapy was not as effective as the preservation of the ovaries. The effect of external irradiation on vaginal shortening was not conspicuous in the case that the ovaries were preserved.

Adolescent↗

PubMed2000

Redox-regulated recruitment of the transcriptional coactivators CREB-binding protein and SRC-1 to hypoxia-inducible factor 1alpha.

Hypoxia-inducible factor 1alpha (HIF-1alpha) functions as a transcription factor that is activated by decreased cellular oxygen concentrations to induce expression of a network of genes involved in angiogenesis, erythropoiesis, and glucose homeostasis. Here we demonstrate that two members of the SRC-1/p160 family of transcriptional coactivators harboring histone acetyltransferase activity, SRC-1 and transcription intermediary factor 2 (TIF2), are able to interact with HIF-1alpha and enhance its transactivation potential in a hypoxia-dependent manner. HIF-1alpha contains within its C terminus two transactivation domains. The hypoxia-inducible activity of both these domains was enhanced by either SRC-1 or the CREB-binding protein (CBP)/p300 coactivator. Moreover, at limiting concentrations, SRC-1 produced this effect in synergy with CBP. Interestingly, this effect was strongly potentiated by the redox regulatory protein Ref-1, a dual-function protein harboring DNA repair endonuclease and cysteine reducing activities. These data indicate that all three proteins, CBP, SRC-1, and Ref-1, are important components of the hypoxia signaling pathway and have a common function in regulation of HIF-1alpha function in hypoxic cells. Given the absence of cysteine residues in one of the Ref-1-regulated transactivation domains of HIF-1alpha, it is thus possible that Ref-1 functions in hypoxic cells by targeting critical steps in the recruitment of the CBP-SRC-1 coactivator complex.

Animals↗