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S W Kang

Publications and source records attributed to S W Kang.

At least 73 records · Page 4Linked to original sources
PubMed1999

Characterization of the murine gene encoding 1-Cys peroxiredoxin and identification of highly homologous genes.

A new type of peroxiredoxin, named 1-Cys peroxiredoxin (1-Cys Prx), reduces hydrogen peroxide with the use of electrons from unidentified electron donor(s). We have isolated the mouse gene encoding 1-Cys Prx (CP-3) and shown that it is comprised of five exons and four introns. Analysis of 5' flanking regions revealed binding sequences of several putative transcription factors such as Sp1, Pit-1a, c-Jun, c-Myc and YY1. It is noticeable that several potential Sp1 binding sites assigned the -60 through -96bp from putative transcription initiation site. The gel shift assays showed that Sp1 and Pit-1a bind specifically to each binding site in 1-Cys Prx promoter. We also isolated two highly related genes such as CP-2 and CP-5. These genes are encoded by single exons, and show 85% of nucleotide sequence homology with the CP-3. The structural features of these genes suggest that they might be intronless genes derived from the CP-3 by the mechanism involving retrotransposition. In addition, our data suggest that they are inserted to a specific site of the mouse L1 repetitive element. The 1-Cys Prx was actively transcribed in a variety of adult tissues as well as in the developing embryos. These results suggest that only the 1-Cys Prx gene might be relevant for studying the function of the 1-Cys Prx in the murine system.

Amino Acid Sequence↗
PubMed1999

Opioid receptor gene: cytokine response element and the effect of cytokines.

Previous studies demonstrated that cytokines regulate opioid and opioid receptor gene expression in neuronal and immune cells. The gene sequence analysis of opioid receptors revealed that mu-, delta- and kappa-opioid receptor promoter regions contain potential cytokine response elements (NF-IL6 binding sites). It was postulated that the response elements present in opioid receptor promoter regions may have a role in the cytokine effects on opioid receptor gene expression through cis-trans interaction. The present study investigated whether cytokines have an effect on opioid receptor gene expression by cytokine-induced transcription factor, NF-IL6, using a number of immune cell lines which respond to cytokines. Further investigation was made to determine whether the potential cytokine response element DNA sequences on opioid receptor promoter region have functional significance which may be affected by the DNA context of the opioid receptor promoter in immune cell lines. Tandem repeats of conserved cytokine response elements of IL-6 gene fused to a heteropromoter SV40 were utilized as a positive control and expressed 2-fold increased promoter activity after cytokine stimulation. Transient transfection studies in time courses (24-72 h) and different dose treatments (100-500 U/ml for IL-6 and 50-200 U/ml for IL-1 alpha+beta) were also carried out to investigate the possibility that the upregulated gene expression may be transient or cytokine-dose-dependent. Our data demonstrated that there was no significant cytokine-stimulated opioid receptor gene expression in immune cells tested. In addition, the cytokine response elements (NF-IL6 binding sites) in opioid receptor genes are not functional. These results contradict the previous reports in which cytokines modulated the expression of opioid and opioid receptors in neuronal and immune cells. The possible reasons regarding the different results were discussed.

Binding Sites↗
PubMed1999

Functional studies on the interaction between human replication protein A and Xeroderma pigmentosum group A complementing protein (XPA).

The human replication protein A (RPA; also known as human single-stranded DNA binding protein, HSSB) is a multisubunit complex (70, 34 and 11 kDa subunits) involved in the three processes of DNA metabolism; replication, repair, recombination. We found that both 34 and 70 kDa subunits (p34 and p70, respectively), of RPA interacts with the Xeroderma pigmentosum group A complementing protein (XPA), a protein that specifically recognizes UV-damaged DNA. Our mutational analysis indicated that no particular domains of RPA p70 were essential for its interaction with XPA. We also examined the effect of this XPA-RPA interaction on in vitro simian virus 40 (SV40) DNA replication catalyzed by the crude extract and monopolymerase system. XPA inhibited SV40 DNA replication in vitro through its interaction with RPA. Taken together, these results suggest that there is a role for RPA in the regulation of DNA metabolism through its ability to modulate the interactions of proteins involved in the processes of DNA metabolism.

Animals↗
PubMed1999

Purification and characterization of a second type thioredoxin peroxidase (type II TPx) from Saccharomyces cerevisiae.

A yeast peroxidase that reduces H2O2 and alkyl hydroperoxides with the use of reducing equivalents provided by thioredoxin was identified previously and named thioredoxin peroxidase (TPx) [Chae, H. Z., Chung, S. J., and Rhee, S. G. (1994) J. Biol. Chem. 269, 27670-27678]. A second type thioredoxin-dependent peroxidase, named type II TPx, has now been purified from yeast, and several peptide sequences have been obtained. Using those sequences, the corresponding cDNA has been identified from the GenBank database. Comparison of the predicted sequence of 176 amino acids of type II TPx with that of the 195 residues of TPx, now renamed type I TPx, revealed no substantial homology except for a short segment preceding Cys62 of type II TPx. Kinetic characterization of the reactions catalyzed by type I and II TPxs revealed that type I preferentially reduces H2O2 rather than alkyl hydroperoxides, whereas type II shows the reverse specificity. Type II TPx contains three cysteine residues at positions 31, 62, and 120. Experiments with mutant proteins in which these three cysteine residues were replaced individually with serine suggest that Cys62-SH constitutes the site of oxidation by peroxides and that the oxidized Cys62 reacts with the Cys120-SH group of another type II TPx molecule to form an intermolecular disulfide linkage. The formed disulfide can then be reduced by thioredoxin, but not by glutathione. Thus, type II TPx mutants lacking Cys62 or Cys120 showed no detectable TPx activity, whereas mutation of Cys31 had no effect on TPx activity. An antioxidant function of type II TPx in intact cells was demonstrated by the observation that Escherichia coli cells overexpressing wild-type protein were less sensitive to inhibition of growth by alkyl hydroperoxides than were control cells or cells overexpressing the mutant protein lacking Cys62.

Amino Acid Sequence↗
PubMed1999

Characterization of three isoforms of mammalian peroxiredoxin that reduce peroxides in the presence of thioredoxin.

A peroxidase from yeast that reduces H2O2 with the use of electrons provided by thioredoxin (Trx) together with homologs from a wide variety of species constitute the peroxiredoxin (Prx) family of proteins. Twelve mammalian Prx members have been previously identified in association with various cellular functions apparently unrelated to peroxidase activity. These mammalian proteins have now been divided into three distinct types, Prx I, II, and III, on the basis of their deduced amino acid sequences and immunological reactivity. With the use of recombinant proteins, Prx I, II, and III have now been shown to possess peroxidase activity and to rely on Trx as a source of reducing equivalents. None of the three proteins exhibited peroxidase activity in the presence of glutaredoxin. All three enzymes showed similar kinetic properties: the Vmax was 6-13 micromol/min per mg at 37 degrees C, the Km for Trx was 3-6 microM, and the Km for H2O2 was < 20 microM. Immunoblot analysis of various rat tissues and cultured cells indicated that most cell types contain the three Prx isoforms, the sum of which amounts to approximately 1-10 microg per milligram of soluble protein. Prx I and II are cytosolic proteins, whereas Prx IlI is localized in mitochondria. These results suggest that, together with glutathione peroxidase and catalase, Prx enzymes likely play an important role in eliminating peroxides generated during metabolism as well as during stimulation of cell surface receptors.

3T3 Cells↗
PubMed1999

Bovine herpes virus expressing envelope protein (E2) of bovine viral diarrhea virus as a vaccine candidate.

The gene encoding the envelope protein (E2) of bovine viral diarrhea virus (BVDV) was expressed under the thymidine kinase (TK) promoter of Korean bovine herpesvirus 1 (BHV-1) isolate. Thymidine kinase negative (TK-) BHV-1 recombinants expressing E2 of BVDV were constructed and the expression of E2 was identified by immunofluorescence and Western blotting. Compared to wild type BHV-1, the recombinant BHV-1 had a delayed cytopathogenic effect in cells. The immunogenicity of the recombinant BHV-1 was examined in guinea pigs and cattle. Although an increase in body temperature was detected for a few days, the inoculated cattle returned to normal temperature with the development of neutralizing antibodies to BVDV.

Animals↗
PubMed1999

Molecular cloning and characterization of a cDNA encoding a transferrin homolog from Bombyx mori.

We isolated a cDNA representing a message that was strongly induced by injection with E. coli in Bombyx mori. The 2160 bp cDNA has an open reading frame of 644 amino acids and the deduced product a predicted molecular mass of 71 kDa. The cDNA sequence shared high homology with the transferrins known so far, and its deduced peptide had unique features of transferrins, that is, sites of cystein residues and iron binding. We suggest that the B. mori transferrin plays an important role in the self-defense system.

Amino Acid Sequence↗
PubMed1999

Up-regulation of clusterin (sulfated glycoprotein-2) in pancreatic islet cells upon streptozotocin injection to rats.

Clusterin is a heterodimeric glycoprotein which has been shown to play important roles in programmed cell death and/or in tissue reorganization not only during embryonic development but also in damaged tissues. Recently, we reported the transient induction of clusterin in pancreatic endocrine cells during early developmental stages of islet formation. In the present study, we have investigated the expression of clusterin in pancreatic tissue of streptozotocin-treated rats which were undergoing extensive islet tissue reorganization due to degeneration of insulin beta cells. Clusterin was found in endocrine cells identified as glucagon-secreting alpha cells at the periphery of the islet. Using immunoelectron microscopy, clusterin-positive cells showed the typical ultrastructural features of pancreatic alpha cells. In addition, colocalization of clusterin and glucagon in the same secretory granules was shown by double immunogold labeling. These results imply that clusterin is a secretory molecule having endocrine and/or paracrine actions in parallel with glucagon. Further, we noted that clusterin expression was increased in pancreatic alpha cells during the process of beta cell death upon streptozotocin injection. The increase was significant as early as 1-3 h after streptozotocin treatment prior to any morphological alteration of islet beta cell and any manifestation of hyperglycemia. The expression of clusterin was steady-stately up-regulated during the process of islet reorganization caused by streptozotocin-induced cytotoxic injury. Therefore, we suggest that clusterin might be considered as a molecule induced by both embryonic development and drug-induced reorganization of the endocrine pancreas. Since clusterin expression is up-regulated in alpha cells, but not in beta cells undergoing degeneration, it may play a protective role against the cytotoxic insult.

Animals↗
PubMed1999

Expression of major piroplasm protein (p33) of Theileria sergenti (Korean isolate) and its immunogenicity in guinea pigs.

To investigate the development of a subunit vaccine against theileriosis in cattle, the DNA fragments encoding piroplasm surface protein (p33) of Theileria sergenti of a Korean isolate were expressed in baculoviruses. The expressed p33 was characterized by indirect fluorescent antibody (IFA) and western blotting analysis. The expression of p33 was mainly detected on the surface of infected Sf21 cells by IFA. The immunoblotting analysis revealed the presence of a same molecular weight protein band of p33. The antigenicity of expressed polypeptide was further examined through the inoculation of a guinea pig. The sera of guinea pigs immunized with p33 expressed cell lysate showed similar fluorescent antibody patterns and reacted with the same molecular weight protein of T. sergenti in immunoblotting analysis, thus indicating that this protein can be a promising candidate for a subunit vaccine in the future.

Animals↗
PubMed1999

Early rehabilitation program in postmastectomy patients: a prospective clinical trial.

The purpose of this study was to determine whether 20 patients who received an early postmastectomy rehabilitation treatment program showed more improvement in range of shoulder motion and functional activities than 13 patients who received instruction for exercise only. Data were obtained at preoperatively, three days after operation, at discharge and at postdischarge one month for each patient on parameters such as range of motion of the ipsilateral shoulder joint, upper extremity circumferential measurements, as well as 10 elements of shoulder function. Postoperatively, both groups showed an increased range of motion of the shoulder joint and improved functional activities, but the group that received postoperative rehabilitation management had a better range of shoulder motion and less difficulty in five items for functional assessment. This study also showed that an early rehabilitation program did not increase postoperative complications. We concluded that an early rehabilitation program or intensive instruction program only by a well-trained physical therapist or physiatrist was beneficial to postmastectomy patients in regaining the function and range of shoulder motion, and significantly better in a rehabilitation group.

Adult↗
PubMed1999

Current status of peritoneal dialysis in Korea: efforts to achieve optimal outcome.

Since its introduction in 1981, peritoneal dialysis (PD) has become firmly established as an effective mode of renal replacement therapy and serves an increasing patient population in Korea. The latest registry data indicate that about 3700 end-stage renal disease patients are maintained on chronic PD, representing 24.1% of the country's dialysis population. The majority (93.3%) of these patients are on continuous ambulatory peritoneal dialysis (CAPD) using the two-bag disconnect system, while only 3.3% are on automated PD. Under current renal reimbursement policies, most dialysis patients have to pay 20% of dialysis fees. Thus CAPD patients on 4 x 2-L daily exchanges pay about US$200 per month, not including medication and travel costs. Traditionally, most PD centers in Korea have used the "standard" prescription of 4 exchanges of 2 L of solution for most of their patients. A recent survey of 1467 patients who commenced CAPD in 1997 revealed that 84% of these patients were initially prescribed 4 x 2-L exchanges, while 12% were given a daily volume of 6 L. With this standard prescription, the percentages of Korean CAPD patients initially achieving the adequacy target of Kt/V urea > or = 2.0 and standardized creatinine clearance (SCCr) > or = 60 L/week/1.73 m2, were 74.4% and 82.1%, respectively. It is likely that, among current Korean CAPD patients, a much lower percentage will achieve the clearance targets compared to this initial outcome, but the precise data are not available. However, it is not clear whether the levels of small-solute clearance recommended for optimal PD outcomes, and proposed by the NKF-DOQI guidelines, will bring the expected benefits to Korean patients. Overall survival of Korean PD patients appears to be as good as, or even better than, that in most other countries. Recently, a single large PD center reported patient survival of 92.1%, 85.6%, 81.4%, and 67.6% at 1, 2, 3, and 5 years respectively. Other centers also reported similar outcomes. As in other countries, cardiovascular deaths predominate among Korean patients: death was due to cardiac causes in 29%, to vascular causes in 21%, and to infectious causes in 24%. Peritonitis is the most important barrier to prolonged use of CAPD in Korea, and more PD patients transfer to hemodialysis because of peritonitis than in other countries. To further reduce the morbidity and mortality of Korean PD patients, various control measures need to be implemented that can reduce or prevent peritonitis and other infectious complications. Also, to further improve long-term patient outcome, Korean nephrologists need to establish and practice optimal clearance targets in the chronic care of these patients.

Cause of Death↗
PubMed1999

Influence of apolipoprotein E genotype on lipid and lipoprotein levels in continuous ambulatory peritoneal dialysis patients.

Apolipoprotein (Apo) E has an important role in triglyceride (TG)-rich lipoprotein metabolism, and the genotype of Apo E is associated with premature coronary artery disease. Patients undergoing continuous ambulatory peritoneal dialysis (CAPD) develop various abnormalities of lipid metabolism and are prone to develop accelerated atherosclerosis. To investigate the distribution of Apo E genotype, and to evaluate the influence of Apo E polymorphism on lipid metabolism in CAPD patients, we measured Apo E genotypes, serum lipid, and lipoprotein levels in 54 CAPD patients (M:F = 1:1). The most common genotype of Apo E in the CAPD patients was E 3/3, found in 68.5%. The frequencies of the other genotypes were E 2/3, found in 14.8%, and E 4/3, found in 16.7%. No genotypic differences in Apo E were seen in the patients with regard to the presence of diabetes, the level of parathyroid hormone, or the transport characteristics of the peritoneal membrane. When comparing lipid levels by Apo E genotype, the total cholesterol and TG levels of E 2/3 patients were significantly higher than those of E 3/3 or E 4/3 patients. The differences in high-density or low-density lipoprotein cholesterol levels by Apo E genotype were not significant. In comparing lipoprotein levels by Apo E genotype, the Apo B and lipoprotein (a) levels of E 2/3 patients were significantly lower than those of E 3/3 or E 4/3 patients. In conclusion, the Apo E 3/3 genotype seems to be the most common genotype in CAPD patients, and the Apo E 2/3 genotype appears to be associated with high cholesterol and TG levels. These results demonstrate the need for further prospective studies in these subjects aimed at elucidating the impact of genetic variation at the Apo E locus on the development of atherosclerosis.

Apolipoproteins E↗
PubMed1998

Cloning and expression of a novel gene encoding a new antibacterial peptide from silkworm, Bombyx mori.

We differentially screened a novel gene encoding a new antibacterial peptide from the immunized Bombyx mori cDNA library. The gene showed a similar structure to that of cecropin-family, encoding 59 amino acids including a putative leader peptide and mature peptide. The deduced peptide, named Enbocin, had conserved amino acid residues which have been known to play an important role in the antibacterial activities. Enbocin genomic sequence revealed that the transcription unit of Enbocin gene was about 1.2 kb, and the coding sequence was interrupted by an intron of 660 bases. Recombinant Enbocin, expressed under the control of the baculovirus polyhedrin promoter, demonstrated a broad range of antibacterial activities against gram positive and gram negative bacteria.

Amino Acid Sequence↗
PubMed1998

Crystallization and preliminary X-ray studies of hORF6, a novel human antioxidant enzyme.

HORF6 is a member of the novel antioxidant enzyme family found in humans. A recombinant form of hORF6 expressed and purified from E. coli has been crystallized by the hanging-drop method using various PEG's as precipitating agents. HORF6 crystallizes in two different monoclinic space groups, P21 and C2. The P21 crystals have unit-cell dimensions of a = 47.85, b = 75.17, c = 63.30 A and beta = 110.21 degrees and contain two monomers per asymmetric unit, while the C2 crystals have unit-cell dimensions of a = 165.27, b = 95.44, c = 166.44 A and beta = 128.97 degrees and contain more than six monomers per asymmetric unit. The P21 crystals with the smaller unit cell diffract X-rays better and behave well for the X-ray analysis. A native data set from a single crystal of the P21 space group gas been collected to 2.0 A resolution.

Antioxidants↗
PubMed1998

Mammalian peroxiredoxin isoforms can reduce hydrogen peroxide generated in response to growth factors and tumor necrosis factor-alpha.

Mammalian tissues express three immunologically distinct peroxiredoxin (Prx) proteins (Prx I, II, and III), which are the products of distinct genes. With the use of recombinant proteins Prx I, II, and III, all have now been shown to possess peroxidase activity and to rely on Trx as a source of reducing equivalents for the reduction of H2O2. Prx I and II are cytosolic proteins, whereas Prx III is localized in mitochondria. Transient overexpression of Prx I or II in cultured cells showed that they were able to eliminate the intracellular H2O2 generated in response to growth factors. Moreover, the activation of nuclear factor kappaB (NFkappaB) induced by extracellularly added H2O2 or tumor necrosis factor-alpha was blocked by overproduction of Prx II. These results suggest that, together with glutathione peroxidase and catalase, Prx enzymes likely play an important role in eliminating peroxides generated during metabolism. In addition, Prx I and II might participate in the signaling cascades of growth factors and tumor necrosis factor-alpha by regulating the intracellular concentration of H2O2.

Animals↗