• The Korean Journal of Physiology and Pharmacology
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• 제24권6호
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• pp.545-553
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• 2020

Aripiprazole is a quinolinone derivative approved as an atypical antipsychotic drug for the treatment of schizophrenia and bipolar disorder. It acts as with partial agonist activities at the dopamine D2 receptors. Although it is known to be relatively safe for patients with cardiac ailments, less is known about the effect of aripiprazole on voltage-gated ion channels such as transient A-type K⁺ channels, which are important for the repolarization of cardiac and neuronal action potentials. Here, we investigated the effects of aripiprazole on Kv1.4 currents expressed in HEK293 cells using a whole-cell patch-clamp technique. Aripiprazole blocked Kv1.4 channels in a concentration-dependent manner with an IC₅₀ value of 4.4 μM and a Hill coefficient of 2.5. Aripiprazole also accelerated the activation (time-to-peak) and inactivation kinetics. Aripiprazole induced a voltage-dependent (δ = 0.17) inhibition, which was use-dependent with successive pulses on Kv1.4 currents without altering the time course of recovery from inactivation. Dehydroaripiprazole, an active metabolite of aripiprazole, inhibited Kv1.4 with an IC₅₀ value of 6.3 μM (p < 0.05 compared with aripiprazole) with a Hill coefficient of 2.0. Furthermore, aripiprazole inhibited Kv4.3 currents to a similar extent in a concentration-dependent manner with an IC₅₀ value of 4.9 μM and a Hill coefficient of 2.3. Thus, our results indicate that aripiprazole blocked Kv1.4 by preferentially binding to the open state of the channels.

• 생명과학회지
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• 제12권1호
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• pp.32-42
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• 2002

합성된 hexanoylthiocholine을 기질로 하여 butyrylcholinesterase와의 반응을 연구하였다. 기질의 농도 변화에 따른 초기반응속도 관찰을 통해 아실기의 탄소수가 증가함에 따라 반응성은 감소하나 $K_{m}$ 값은 0.140(mM)으로 더 강한 ES 복합체를 형성함을 알 수 있었다. Hexanoylthio-choline의 촉매화된 acetylcholinesterase 가수분해에 대한 pH-V/K profile에서 p $K_{a}$ 값 4.974$\pm$0.02을 얻었다. 이는 최근 문헌의 보고와 상통하는 것으로 p $K_{a}$ =6.2~6.4를 갖는 잔류물의 기본형에 활성이 의존하는 것으로부터 하나의 잔류물 또는 p $K_{a}$ =4.7~5.0을 갖는 잔류물들의 촉매작용으로 계통적인 자리밀림을 보여준다. 이는 촉매화된 BChE의 활성영역 esteratic site 주변에 긴 사슬 아실기의 가수분해에 관여하는 새로운 활성영역이 존재함을 밝히는 증거이다. 분자 조형은 기질의 아실기의 탄소수에 따라 acetylcholinesterase에 의해 표현되어지는 반응과정의 변화의 합리성을 제공한다. 본 연구에서는 한국과학기술원 도핑컨트롤센터와 연계하여 acetylcholinesterase와 기질인 acylthiocholine과의 입체적으로 둘러싸인 acyl-binding site를 분자 조형하고자 노력 중에 있다.

• Bulletin of the Korean Chemical Society
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• 제18권9호
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• pp.916-922
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• 1997

A superconducting phase La2CuO4+δ (Tc=44 K) has been prepared by electrochemical oxidation which allows the oxygen to intercalat into the La2O2 layers. According to the Cu K-edge X-ray absorption near edge structure spectroscopic analysis, the oxidized phase shows an overall spectra shift of about 0.5 eV to a higher energy region compared to the as sintered one with the occurrence of an additional peak corresponding to the transition to the |1s13dn+1L-14pσ1 > final state, indicating the oxidation of CuO2 layer. From the X-ray photoelectron spectroscopic studies, it is found that the binding energy of La 3d5/2 is significantly shifted from 834.3 eV (as sintered La2CuO4) to 833.6 eV (as electrochemically oxidized La2CuO4+δ), implying that the covalency of the (La-O) bond is decreased due to the oxygen intercalation. The O 1s spectra do not provide an evidence of the superoxide or peroxide, but the oxide (O2-) with the contaminated carbonate (CO32-) based on the peaks at 529 eV and 532 eV, respectively, which is clearly confirmed by the Auger spectroscopic analysis. Oxygen contents determined by iodometric titration (δ=0.07) and thermogravimetry (δ=0.09) show good coincidence each other, also giving an evidence for the "O2-" nature of excess oxygen. From the above results, it is concluded that "O2-" appeared as O 1s peak at 528.6 eV is responsible for superconductivity of La2CuO4+δ.

• Journal of Microbiology and Biotechnology
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• 제31권4호
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• pp.520-528
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• 2021

Plesiomonas shigelloides, a member of the family Vibrionaceae, is a gram-negative, rod-shaped, facultative anaerobic bacterium with flagella. P. shigelloides has been isolated from such sources as freshwater, surface water, and many wild and domestic animals. P. shigelloides contains 102 O-antigens and 51 H-antigens. The diversity of O-antigen gene clusters is relatively poorly understood. In addition to O1 and O17 reported by other laboratories, and the 12 O serogroups (O2, O10, O12, O23, O25, O26, O32, O33, O34, O66, O75, and O76) reported previously by us, in the present study, nine new P. shigelloides serogroups (O8, O17, O18, O37, O38, O39, O44, O45, and O61) were sequenced and annotated. The genes for the O-antigens of these nine groups are clustered together in the chromosome between rep and aqpZ. Only O38 possesses the wzm and wzt genes for the synthesis and translocation of O-antigens via the ATP-binding cassette (ABC) transporter pathway; the other eight use the Wzx/Wzy pathway. Phylogenetic analysis using wzx and wzy showed that both genes are diversified. Among the nine new P. shigelloides serogroups, eight use wzx/wzy genes as targets. In addition, we developed an O-antigen-specific PCR assay to detect these nine distinct serogroups with no cross reactions among them.

• 미생물학회지
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• 제55권1호
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• pp.1-8
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• 2019

Due to the major role played by several species of Streptococcus in the etiology of periodontitis, it is important to assess the pattern of Streptococcus pathogenic pathways within the infected subgingival pockets using a bacterial specific 16S rRNA fragment. From the total of 50 patients with periodontitis included in the study, only 23 Streptococcal isolates were considered for further analyses, in which their 16S rRNA fragments were amplified and sequenced. Then, a comprehensive phylogenetic tree was constructed and in silico prediction was performed for the observed Streptococcal species. The phylogenetic analysis of the subgingival Streptococcal species revealed a high discrimination power of the 16S rRNA fragment to accurately identify three groups of Streptococcus on the species level, including S. salivarius (14 isolates), S. anginosus (5 isolates), and S. gordonii (4 isolates). The employment of state-of-art in silico tools indicated that each Streptococcal species group was characterized with particular transcription factors that bound exclusively with a different 16S rRNA-based secondary structure. In conclusion, the observed data of the present study provided in-depth insights into the mechanism of each Streptococcal species in its pathogenesis, which differ in each observed group, according to the differences in the 16S rRNA secondary structure it takes, and the consequent binding with its corresponding transcription factors. This study paves the way for further interventions of the in silico prediction, with the main conventional in vitro microbiota identification to present an interesting insight in terms of the gene expression pattern and the signaling pathway that each pathogenic species follows in the infected subgingival site.

• The Korean Journal of Physiology and Pharmacology
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• 제23권5호
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• pp.419-426
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• 2019

Mosapride accelerates gastric emptying by acting on 5-hydroxytryptamine type 4 ($5-HT_4$) receptor and is frequently used in the treatment of gastrointestinal (GI) disorders requiring gastroprokinetic efficacy. We tested the effect of mosapride on 5-hydroxytryptamine type 3 ($5-HT_3$) receptor currents because the $5-HT_3$ receptors are also known to be expressed in the GI system and have an important role in the regulation of GI functions. Using the whole-cell voltage clamp method, we compared the currents of the $5-HT_3$ receptors when 5-HT was applied alone or was co-applied with mosapride in cultured NCB-20 cells known to express $5-HT_3$ receptors. The $5-HT_3$ receptor current amplitudes were inhibited by mosapride in a concentration-dependent manner. Mosapride blocked the peak currents evoked by the application of 5-HT in a competitive manner because the $EC_{50}$ shifted to the right without changing the maximal effect. The rise slopes of $5-HT_3$ receptor currents were decreased by mosapride. Pre-application of mosapride before co-application, augmented the inhibitory effect of mosapride, which suggests a closed channel blocking mechanism. Mosapride also blocked the opened $5-HT_3$ receptor because it inhibited the $5-HT_3$ receptor current in the middle of the application of 5-HT. It accelerated desensitization of the $5-HT_3$ receptor but did not change the recovery process from the receptor desensitization. There were no voltage-, or use-dependency in its blocking effects. These results suggest that mosapride inhibited the $5-HT_3$ receptor through a competitive blocking mechanism probably by binding to the receptor in closed state, which could be involved in the pharmacological effects of mosapride to treat GI disorders.

• Journal of Ginseng Research
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• 제43권3호
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• pp.452-459
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• 2019

Background: Ginsenoside compound K(C-K), a major metabolite of ginsenoside, exhibits anticancer activity in various cancer cells and animal models. A cell signaling study has shown that C-K inhibited nuclear factor-kappa B ($NF-{\kappa}B$) pathway in human astroglial cells and liver cancer cells. However, the molecular targets of C-K and the initiating events were not elucidated. Methods: Interaction between C-K and Annexin A2 was determined by molecular docking and thermal shift assay. HepG2 cells were treated with C-K, followed by a luciferase reporter assay for $NF-{\kappa}B$, immunofluorescence imaging for the subcellular localization of Annexin A2 and $NF-{\kappa}B$ p50 subunit, coimmunoprecipitation of Annexin A2 and $NF-{\kappa}B$ p50 subunit, and both cell viability assay and plate clone formation assay to determine the cell viability. Results: Both molecular docking and thermal shift assay positively confirmed the interaction between Annexin A2 and C-K. This interaction prevented the interaction between Annexin A2 and $NF-{\kappa}B$ p50 subunit and their nuclear colocalization, which attenuated the activation of $NF-{\kappa}B$ and the expression of its downstream genes, followed by the activation of caspase 9 and 3. In addition, the overexpression of Annexin A2-K320A, a C-K binding-deficient mutant of Annexin A2, rendered cells to resist C-K treatment, indicating that C-K exerts its cytotoxic activity mainly by targeting Annexin A2. Conclusion: This study for the first time revealed a cellular target of C-K and the molecular mechanism for its anticancer activity.

• 산업식품공학
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• 제21권1호
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• pp.1-11
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• 2017

Dyslipidemia, defined as elevated triglyceride (TG), total- and LDL-C, and/or decreased HDL-C levels, is considered a principal risk factor for cardiovascular disease. The low-density lipoprotein receptor (LDLR) family has been considered a key player in the prevention of dyslipidemia. The LDLR family consists of cytoplasmic membrane proteins and plays an important role not only in ligand-receptor binding and uptake, but also in various cell signaling pathways. Emerging reports state that various functional ingredients dynamically modulate the function of the LDLR family. For instance, oats stimulated the LDLR function in vivo, resulting in decreased body weight and improved serum lipid profiles. The stimulation of LRP6 by functional ingredients in vitro activated the Wnt/${\beta}-catenin$ pathway, subsequently suppressing the intracellular TG via inhibition of SREBP1, $PPAR{\gamma}$, and $C/EBP{\alpha}$. Furthermore, the extract of Cistanchetubulosa enhanced the expression of the mRNA of VLDLR, followed by a reduction in the serum cholesterol level. In addition, fermented soy milk diminished TG and total cholesterol levels while increasing HDL-C levels via activation of LRP1. To summarize, modulating the function of the LDLR family by diverse functional ingredients may be a potent therapeutic remedy for the treatment of dyslipidemia and cardiovascular diseases.

• BMB Reports
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• 제54권9호
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• pp.476-481
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• 2021

Liver receptor homolog-1 (LRH-1) has emerged as a regulator of hepatic glucose, bile acid, and mitochondrial metabolism. However, the functional mechanism underlying the effect of LRH-1 on lipid mobilization has not been addressed. This study investigated the regulatory function of LRH-1 in lipid metabolism in maintaining a normal liver physiological state during fasting. The Lrh-1^f/f and LRH-1 liver-specific knockout (Lrh-1^LKO) mice were either fed or fasted for 24 h, and the liver and serum were isolated. The livers were used for qPCR, western blot, and histological analysis. Primary hepatocytes were isolated for immunocytochemistry assessments of lipids. During fasting, the Lrh-1^LKO mice showed increased accumulation of triglycerides in the liver compared to that in Lrh-1^f/f mice. Interestingly, in the Lrh-1^LKO liver, decreases in perilipin 5 (PLIN5) expression and genes involved in β-oxidation were observed. In addition, the LRH-1 agonist dialauroylphosphatidylcholine also enhanced PLIN5 expression in human cultured HepG2 cells. To identify new target genes of LRH-1, these findings directed us to analyze the Plin5 promoter sequence, which revealed -1620/-1614 to be a putative binding site for LRH-1. This was confirmed by promoter activity and chromatin immunoprecipitation assays. Additionally, fasted Lrh-1^f/f primary hepatocytes showed increased co-localization of PLIN5 in lipid droplets (LDs) compared to that in fasted Lrh-1^LKO primary hepatocytes. Overall, these findings suggest that PLIN5 might be a novel target of LRH-1 to mobilize LDs, protect the liver from lipid overload, and manage the cellular needs during fasting.

• Journal of Yeungnam Medical Science
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• 제38권4호
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• pp.326-336
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• 2021

Background: Sulfation of heparan sulfate proteoglycans (HSPGs) is critical for the binding and signaling of ligands that mediate inflammation. Extracellular 6-O-endosulfatases regulate posttranslational sulfation levels and patterns of HSPGs. In this study, extracellular 6-O-endosulfatases, sulfatase (Sulf)-1 and Sulf-2, were evaluated for their expression and function in inflammatory cells and tissues. Methods: Harvested human peripheral blood mononuclear cells were treated with phytohemagglutinin and lipopolysaccharide, and murine peritoneal macrophages were stimulated with interleukin (IL)-1β for the evaluation of Sulf-1 and Sulf-2 expression. Sulf expression in inflammatory cells was examined in the human rheumatoid arthritis (RA) synovium by immunofluorescence staining. The antigen presentation and phagocytic activities of macrophages were compared according to the expression state of Sulfs. Sulfs-knockdown macrophages and Sulfs-overexpressing macrophages were generated using small interfering RNAs and pcDNA3.1 plasmids for Sulf-1 and Sulf-2, respectively. Results: Lymphocytes and monocytes showed weak Sulf expression, which remained unaffected by IL-1β. However, peritoneal macrophages showed increased expression of Sulfs upon stimulation with IL-1β. In human RA synovium, two-colored double immunofluorescent staining of Sulfs and CD68 revealed active upregulation of Sulfs in macrophages of inflamed tissues, but not in lymphocytes of lymphoid follicles. Macrophages are professional antigen-presenting cells. The antigen presentation and phagocytic activities of macrophages were dependent on the level of Sulf expression, suppressed in Sulfs-knockdown macrophages, and enhanced in Sulfs-overexpressing macrophages. Conclusion: The results demonstrate that upregulation of Sulfs in macrophages occurs in response to inflammation, and Sulfs actively regulate the antigen presentation and phagocytic activities of macrophages as novel immune regulators.