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Seung Hwan Lee

Publications and source records attributed to Seung Hwan Lee.

15 recordsLinked to original sources
PubMed2025

Advances in large-scale DNA engineering with the CRISPR system.

In recent years, DNA engineering technology has undergone significant advancements, with clustered regularly interspaced short palindromic repeats (CRISPR)-based target-specific DNA insertion emerging as one of the most rapidly expanding and widely studied approaches. Traditional DNA insertion technologies employing recombinases typically involve introducing foreign DNA into genes in vivo by either pre-engineering recognition sequences specific to the recombinase or through genetic crossing to incorporate the requisite recognition sequence into the target gene. However, CRISPR-based gene insertion technologies have advanced to streamline this engineering process by combining the CRISPR-Cas module with recombinase enzymes. This process enables accurate and efficient one-step insertion of foreign DNA into the target gene in vivo. Here we provide an overview of the latest developments in CRISPR-based gene insertion technologies and discusses their potential future applications.

CRISPR-Cas Systems↗
PubMed2025

Precise progerin targeting using RfxCas13d: A therapeutic avenue for Hutchinson-Gilford progeria syndrome.

Hutchinson-Gilford progeria syndrome (HGPS), an extremely rare progressive genetic disorder, is caused by a point mutation in LMNA that induces progerin production, which disrupts cellular function and triggers premature aging and mortality. Despite extensive efforts, HPGS remains incurable. We successfully implemented a strategy using RfxCas13d to selectively target progerin mRNA at specific junction regions, without unintended cleavage and reduce its expression. This technique discriminated between normal lamin A and progerin, thus providing a safe and targeted therapeutic avenue to treat HGPS. Our approach effectively restored aberrant gene expression and progerin-induced cellular phenotypes, including senescence, mitochondrial dysfunction, and DNA damage in cells with HGPS and LMNAG608G/G608G mice. Notably, LMNAG608G/G608G mice exhibited improved progeroid phenotypes, suggesting a potential therapeutic application of this approach for other diseases resulting from abnormal RNA splicing.

Progeria↗
PubMed2005

A strategy to increase the efficiency of the dye-sensitized TiO2 solar cells operated by photoexcitation of dye-to-TiO2 charge-transfer bands.

Dye-sensitized nanoporous TiO2 solar cells (DSSCs) can be classified into two types, namely, Type-I and Type-II. Type-I DSSCs are the DSSCs in which electrons are injected from the adsorbed dyes by photoexcitation of the dyes followed by electron injection from the excited dyes to TiO2 (pathway A). Type-II DSSCs are the DSSCs in which electrons are injected not only by pathway A but also by direct one-step electron injection from the dyes to TiO2 by photoexcitation of the dye-to-TiO2 charge-transfer (DTCT) bands (pathway B). The DSSCs employing catechol (Cat) or its derivatives as the sensitizers have been the typical examples of Type-II DSSCs. However, their solar energy-to-electricity conversion efficiencies (eta) have never exceeded 0.7%, and the external quantum efficiencies (EQE) at the absorption maximums of the DTCT bands have never exceeded 10%. We found that the attachment of electron-donating compounds such as (pyridin-4-yl)vinyl and (quinolin-4-yl)vinyl, respectively, to Cat (designated as Cat-v-P and Cat-v-Q, respectively) leads to 2- and 2.7-fold increases, respectively, in eta, driven by large increases in short circuit current (Jsc). The EQE increased from 8.5 to 30% at 400 nm upon changing from Cat to Cat-v-P, at which only the DTCT band absorbs. In the case of the Cat-v-Q-sensitized DSSC, even the eta obtained by exciting only the DTCT band was higher than 1%. Interestingly, the illumination of only the DTCT band resulted in the increase of fill factor from 62.6% to 72.3%. This paper provides for the first time an insight into the strategy to increase the eta values of Type-II DSSCs.

Adsorption↗
PubMed2005

Feasibility of the radial artery as a vascular access route in performing primary percutaneous coronary intervention.

We aimed to evaluate the feasibility of transradial primary percutaneous coronary intervention (PCI) in patients with ST elevation myocardial infarction (STEMI) by comparing the procedural results and complications with those of transfemoral intervention. From April 1997 to October 2004, we enrolled 352 consecutive cases of STEMI who underwent primary PCI. The femoral route was used in 132 cases (TFI group) and the radial route was used in 220 cases (TRI group). Cases with Killips class IV, a negative Allen test or a non-palpable radial artery were excluded from our study. Baseline clinical and angiographic profiles were comparable in both groups. Vascular access time was 3.8 +/- 3.5 min in the TFI group and 3.6 +/- 3.1 min in the TRI group, and cath room to reperfusion time was 25 +/- 11 min in the TRI group and 26 +/- 13 min in the TRI group. The procedural success rate was 89% in the TFI group and 88% in the TRI group. Crossover occurred in 9 cases (4%) due to approaching vessel tortuosity in the TRI group. Major access site complications occurred in 7 cases (5%) in the TFI group, and there were no complications in the TRI group (p < 0.001). Although radial occlusion occurred in 5 cases of the TRI group, there was no evidence of hand ischemia. The total hospital stay was significantly shorter in TRI group than in TFI group. In conclusion, use of the radial artery might be a potential vascular access route in performing primary PCI in selected cases.

Adult↗
PubMed2005

Display of lipase on the cell surface of Escherichia coli using OprF as an anchor and its application to enantioselective resolution in organic solvent.

We have developed a new cell surface display system using a major outer membrane protein of Pseudomonas aeruginosa OprF as an anchoring motif. Pseudomonas fluorescens SIK W1 lipase gene was fused to the truncated oprF gene by C-terminal deletion fusion strategy. The truncated OprF-lipase fusion protein was successfully displayed on the surface of Escherichia coli. Localization of the truncated OprF-lipase fusion protein was confirmed by western blot analysis, immunofluorescence microscopy, and whole-cell lipase activity. To examine the enzymatic characteristics of the cell surface displayed lipase, the whole-cell enzyme activity and stability were determined under various conditions. Cell surface displayed lipase showed the highest activity at 37 degrees C and pH 8.0. It retained over 80% of initial activity after incubation for a week in both aqueous solution and organic solvent. When the E. coli cells displaying lipases were used for enantioselective resolution of racemic 1-phenylethanol in hexane, (R)-phenyl ethyl acetate was successfully obtained with the enantiomeric excess of greater than 96% in 36 h of reaction. These results suggest that E. coli cells displaying lipases using OprF as an anchoring motif can be employed for various biotechnological applications both in aqueous and nonaqueous phases.

Bacterial Outer Membrane Proteins↗
PubMed2005

Telomerase activity and cell proliferation index in cholesteatoma.

CONCLUSIONS: Telomerase activity was expressed in cholesteatomas, and cellular proliferation was significantly higher in cases where the telomerase activity was positive. Telomerase activity was also closely related with cellular proliferation in chronic hyperproliferating tissues such as cholesteatomas. OBJECTIVE: Telomerase activity is detected in most malignant tumors and is also known to have a close relationship with cell proliferation. Cholesteatoma shows cellular hyperproliferation. We studied telomerase activity in cholesteatoma and its relationship with cellular proliferation and clinical findings. MATERIAL AND METHODS: Cholesteatoma tissue was obtained from 40 patients during middle ear surgery. Telomerase activity was measured using a telomeric repeat amplification protocol method. As a cellular proliferation index, expression of Ki-67 was measured by means of immunohistochemical staining. Posterior auricular skin was used as a control. Telomerase activity was compared with Ki-67 expression. Clinical features such as hearing loss, the extension of cholesteatoma, the degree of bone destruction and the cause of cholesteatomas were compared with telomerase activity and the cellular proliferation index. RESULTS: Telomerase activity was positive in 21/40 cholesteatomas (52.5%), but absent in the control group. The average Ki-67 labeling index in the cholesteatoma group was 32.84+/-10.13, higher than that in the control group (21.83+/-7.76) (p<0.05). The average Ki-67 labeling indices of the 21 telomerase activity-positive and 19 telomerase activity-negative cholesteatomas were 37.76+/-8.53 and 27.39+/-9.06, respectively. The Ki-67 labeling index was significantly higher in telomerase-positive cholesteatomas (p<0.05). The clinical features did not show a relationship with either telomerase activity or the cellular proliferation index.

Adolescent↗
PubMed2005

Cell surface display of lipase in Pseudomonas putida KT2442 using OprF as an anchoring motif and its biocatalytic applications.

We developed a new cell surface display system in Pseudomonas putida KT2442 using OprF, an outer membrane protein of Pseudomonas aeruginosa, as an anchoring motif in a C-terminal deletion-fusion strategy. The Pseudomonas fluorescens SIK W1 lipase gene was fused to two different C-terminal truncated OprF genes, and the fusion genes were cloned into the broad-host-range plasmid pBBR1MCS2 to make pMO164PL and pMO188PL. Plasmid pMO188PL allowed better display of lipase and thus was chosen for further study. The display of lipase on the surface of P. putida KT2442 was confirmed by Western blot analysis, immunofluorescence microscopy, and measurement of whole-cell lipase activity. The whole-cell lipase activity of recombinant P. putida KT2442 harboring pMO188PL was more than fivefold higher than that of recombinant Escherichia coli displaying lipase in the same manner. Cell surface-displayed lipase exhibited the highest activity at 47 degrees C and pH 9.0, and the whole-cell lipase activity was greater than 90% of the initial activity in organic solvents at 47 degrees C for 1 week. In a biocatalytic application, enantioselective resolution of 1-phenyl ethanol was carried out in an organic solvent. (R)-Phenyl ethyl acetate was successfully produced with 41.9% conversion and an enantiomeric excess of more than 99% in a 36-h reaction. These results suggest that the OprF anchor can be used for efficient display of proteins in P. putida KT2442 and consequently for various biocatalytic applications.

Catalysis↗
PubMed2005

Hypoadiponectinemia and insulin resistance are associated with nonalcoholic fatty liver disease.

We investigated the association between nonalcoholic fatty liver disease (NAFLD) and plasma adiponectin levels and insulin resistance. We recruited study subjects among one hundred and eighty one persons who were examined abdominal ultrasound at routine screening tests. A standard interview (consumption of alcohol and medical history), physical examination (height, weight, waist circumference, and blood pressure), and biochemical study (lipid parameters, aminotransferases, fasting plasma glucose, fasting insulin, and plasma adiponectin) were performed. Subjects who consumed alcohol more than moderate, evidence of viral hepatitis, toxic hepatitis, and serious cardiac, renal, or hepatic disease were excluded. Thirty-eight NAFLD patients and 53 control subjects diagnosed by ultrasound were finally analyzed. The plasma adiponectin level was significantly correlated with HDL-cholesterol (r=0. 38, p<0.001), triglycerides (r=-0.22, p=0.04), fasting insulin (r=-0.37, p<0.01), and insulin resistance by homeostasis model of assessment-insulin resistance (HOMAIR) (r=-0.39, p<0.01), after adjusting for age, sex, and adiposity. Multiple logistic regression analysis indicated that HOMA-IR was a significant predictor of having NAFLD (odds ratio [OR]=2.38; 95% confidence interval [CI]: 1.52-5.74), while adiponectin had a protective effect against NAFLD (OR=0.22; 95% CI: 0.09-0.55). We demonstrated that hypoadiponectinemia and insulin resistance are associated with NAFLD independent of obesity.

Adiponectin↗
PubMed2004

Effect of Ganoderma lucidum on the quality and functionality of Korean traditional rice wine, yakju.

The goal of this study was to develop a high value Korean traditional rice wine possessing the pharmaceutical functionality of Ganoderma lucidum. The effects of the fruiting body of G. lucidum on the alcohol fermentation of Korean traditional rice wine, yakju, were investigated. Optimal fermentation conditions for the preparation of G. lucidum-yakju consisted of the koji added at 15% and a fermentation period of 15 d at 25 degrees C. The effects of the amount of G. lucidum added on the acceptability and functionality of G. lucidum-yakju were investigated. G. lucidum GL-1 yakju brewed by adding 0.1% G. lucidum into the mash showed the best acceptability and its angiotensin I-converting enzyme (ACE) inhibitory activity and SOD-like activity were 63% and 42%, respectively, both of which are higher than those of yakju. The high ACE inhibitory activity of G. lucidum GL-1 yakju was found to result from ganoderic acid K in G. lucidum on the basis of physical and spectral data. However, the fibrinolytic activity and antioxidant activity of G. lucidum GL-1 yakju were very low, while tyrosinase inhibitory activity was not determined. From these results, G. lucidum GL-1 yakju may become a new functional Korean traditional rice wine with antihypertensive properties.

Journal Article↗
PubMed2004

Display of bacterial lipase on the Escherichia coli cell surface by using FadL as an anchoring motif and use of the enzyme in enantioselective biocatalysis.

We have developed a novel cell surface display system by employing FadL as an anchoring motif, which is an outer membrane protein involved in long-chain fatty acid transport in Escherichia coli. A thermostable Bacillus sp. strain TG43 lipase (44.5 kDa) could be successfully displayed on the cell surface of E. coli in an active form by C-terminal deletion-fusion of lipase at the ninth external loop of FadL. The localization of the truncated FadL-lipase fusion protein on the cell surface was confirmed by confocal microscopy and Western blot analysis. Lipase activity was mainly detected with whole cells, but not with the culture supernatant, suggesting that cell lysis was not a problem. The activity of cell surface-displayed lipase was examined at different temperatures and pHs and was found to be the highest at 50 degrees C and pH 9 to 10. Cell surface-displayed lipase was quite stable, even at 60 and 70 degrees C, and retained over 90% of the full activity after incubation at 50 degrees C for a week. As a potential application, cell surface-displayed lipase was used as a whole-cell catalyst for kinetic resolution of racemic methyl mandelate. In 36 h of reaction, (S)-mandelic acid could be produced with the enantiomeric excess of 99% and the enantiomeric ratio of 292, which are remarkably higher than values obtained with crude lipase or cross-linked lipase crystal. These results suggest that FadL may be a useful anchoring motif for displaying enzymes on the cell surface of E. coli for whole-cell biocatalysis.

Base Sequence↗
PubMed2002

Innate immunity to cytomegalovirus: the Cmv1 locus and its role in natural killer cell function.

The identification and characterization of genetic loci that contribute to patterns of susceptibility/resistance to infection provide important insights into the mechanisms of innate and adaptive immunity. Genetic heterogeneity across the population makes the characterization of such traits in humans technically difficult; however, inbred animal models represent an ideal tool for such analyses. This review illustrates the power of mouse genetics as utilized for the identification and characterization of the locus conferring early resistance to murine cytomegalovirus infection, Cmv1. This locus encodes an activating C-type lectin receptor of the Ly49 family that promotes natural killer (NK) cell cytolysis of infected cells. Although NK cells are usually able to detect and destroy virally infected cells via recognition of the downregulation of MHC class I molecules, the Cmv1 locus provides the first example of an NK receptor that is able to mediate clearance of viral infection via direct recognition of a virally encoded protein.

Animals↗