• Journal of Life Science
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• v.19 no.8
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• pp.1055-1061
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• 2009

${\alpha}$-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptors are widespread throughout the central nervous system and appear to serve as synaptic receptors for fast excitatory synaptic transmission mediated by glutamate. Their modulation is believed to affect learning and memory. To identify the interaction proteins for the AMPA receptor subunit glutamate receptor-interacting protein 1 (GRIPl), GRIP1 interactions with armadillo family protein p0071/plakophilin-4 were investigated. GRIP1 protein bound to the tail region of p0071/plakophilin-4 but not to other armadillo family protein members in a yeast two-hybrid assay. The "S-X-V" motif at the carboxyl (C)-terminal end of p0071/plakophilin-4 is essential for interaction with GRIP1. p0071/plakophilin-4 interacted with the Postsynaptic density-95/Discs large/Zona occludens-1 (PDZ) domains of GRIPI in the yeast two-hybrid assay, as is indicated also by Glutathione S-transferase (GST) pull-down, and co-immunoprecipitated with GRIP1 antibody in brain fraction. The findings of this study provide evidence that p0071/plakophilin-4 is an interactor of GRIP1.

• Journal of Life Science
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• v.18 no.3
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• pp.336-343
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• 2008

Histone deacetylases (HDACs) inhibitors have emerged as the accessory therapeutic agents for various human cancers, since they can block the activity of specific HDACs, restore the expression of some tumor suppressor genes and induce cell differentiation, cell cycle arrest and apoptosis in vitro and in vivo. In the present study, we investigated that the effect of trichostatin A (TSA), an HDAC inhibitor, on the cell growth and apoptosis, and its effect on the nuclear factor-kappaB $(NF-{\kappa}B)$ activity in 267B1 human prostate epithelial cells. Exposure of 267B1 cells to TSA resulted in growth inhibition and apoptosis induction in and dose-dependent manners as measured by fluorescence microscopy, agarose gel electrophoresis and flow cytometry analysis. TSA treatment inhibited the levels of IAP family members such as c-IAP-1 and c-IAP-2 and induced the proteolytic activation of caspase-3, -8 and -9, which were associated with concomitant degradation of poly (ADP-ribose)-polymerase, ${\beta}-catenin$ and laminin B proteins. The increase in apoptosis by TSA was connected with the translocation of $NF-{\kappa}B$ from cytosol to nucleus, increase of the DNA binding as well as promoter activity of $NF-{\kappa}B$, and degradation of cytosolic inhibitor of KappaB $(I{\kappa}B)-{\alpha}$ protein. We therefore concluded that TSA demonstrated anti-proliferative and apoptosis-inducing effects on 267B1 cells in vitro, and that the activation of caspases and $NF-{\kappa}B$ may play important roles in its mechanism of action. Although further studies are needed, these findings provided important insights into the possible molecular mechanisms of the anti-cancer activity of TSA.

• Journal of Life Science
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• v.28 no.10
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• pp.1233-1243
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• 2018

Sterol regulatory-element binding proteins (SREBPs) are a family of transcription factors that regulate lipid homeostasis and metabolism by controlling the expression of enzymes required for endogenous cholesterol, fatty acid (FA), triacylglycerol, and phospholipid synthesis. The three SREBPs are encoded by two different genes. The SREBP1 gene gives rise to SREBP-1a and SREBP-1c, which are derived from utilization of alternate promoters that yield transcripts in which distinct first exons are spliced to a common second exon. SREBP-2 is derived from a separate gene. Additionally, SREBPs are implicated in numerous pathogenic processes, such as endoplasmic reticulum stress, inflammation, autophagy, and apoptosis. They also contribute to obesity, dyslipidemia, diabetes mellitus, and nonalcoholic fatty liver diseases. Genome-wide analyses have revealed that these versatile transcription factors act as important nodes of biological signaling networks. Changes in cell metabolism and growth are reciprocally linked through SREBPs. Anabolic and growth signaling pathways branch off and connect to multiple steps of SREBP activation and form complex regulatory networks. SREBPs are activated through the PI3K-Akt-mTOR pathway in these processes, but the molecular mechanism remains to be understood. This review aims to provide a comprehensive understanding of the role of SREBPs in physiology and pathophysiology at the cell, organ, and organism levels.

• Molecules and Cells
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• v.25 no.3
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• pp.390-396
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• 2008

Calreticulin (CRT) is one of the major $Ca^{2+}$ binding chaperone proteins of the endoplasmic reticulum (ER) and an unusual luminal ER protein. Postnatally elevated expression of CRT leads to impaired development of the cardiac conductive system and may be responsible for the pathology of complete heart block. In this study, the molecular mechanisms that affect $Ca^{2+}$-dependent signal cascades were investigated using CRT-overexpressing cardiomyocytes. In particular, we asked whether calreticulin plays a critical role in the activation of $Ca^{2+}$-dependent apoptosis. In the cells overexpressing CRT, the intracellular calcium concentration was significantly increased and the activity of PKC and level of SECAR2a mRNA were reduced. Phosphorylation of Akt and ERKs decreased compared to control. In addition the activity of the anti-apoptotic factor, Bcl-2, was decreased and the activities of pro-apoptotic factor, Bax, p53 and caspase 8 were increased, leading to a dramatic augmentation of caspase 3 activity. Our results suggest that enhanced CRT expression in mature cardiomyocytes disrupts intracellular calcium regulation, leading to calcium-dependent apoptosis.

• Herbal Formula Science
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• v.23 no.2
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• pp.199-208
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• 2015

Objectives : In the present study, we investigated the effects of ethanol extract of Scutellaria baicalensis (EESB) on the progression of cell cycle in human renal cell carcinoma Caki-1 cells. Methods : The effects of EESB on cell growth and apoptosis induction were evaluated by trypan blue dye exclusion assay and flow cytometry, respectively. The mRNA and protein levels were determined by Western blot analysis and reverse transcription-polymerase chain reaction, respectively. Results : It was found that EESB treatment on Caki-1 cells resulted in a dose-dependent inhibition of cell growth and induced apoptotic cell death as detected by Annexin V-FITC staining. The flow cytometric analysis indicated that EESB resulted in G2/M arrest in cell cycle progression which was associated with the down-regulation of cyclin A expression. Our results also revealed that treatment with EESB increased the mRNA and proteins expression of tumor suppressor p53 and cyclin-dependent kinase (Cdk) inhibitor p21(WAF1/CIP1), without any noticeable changes in cyclin B1, Cdk2 and Cdc2. In addition, the incubation of cells with EESB resulted in a significant increase in the binding of p21 and Cdk2 and Cdc2. These findings suggest that EESB-induced G2/M arrest and apoptosis in Caki-1 cells is mediated through the p53-mediated upregulation of Cdk inhibitor p21. Conclusions : Taken together, these findings suggest that EESB may be a potential chemotherapeutic agent and further studies will be needed to identify the biological active compounds that confer the anti-cancer activity of S. baicalensis.

• The Korean Journal of Physiology and Pharmacology
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• v.17 no.3
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• pp.223-228
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• 2013

The calcium-activated $K^+$ ($BK_{Ca}$) channel is one of the potassium-selective ion channels that are present in the nervous and vascular systems. $Ca^{2+}$ is the main regulator of $BK_{Ca}$ channel activation. The $BK_{Ca}$ channel contains two high affinity $Ca^{2+}$ binding sites, namely, regulators of $K^+$ conductance, RCK1 and the $Ca^{2+}$ bowl. Lysophosphatidic acid (LPA, 1-radyl-2-hydroxy-sn-glycero-3-phosphate) is one of the neurolipids. LPA affects diverse cellular functions on many cell types through G protein-coupled LPA receptor subtypes. The activation of LPA receptors induces transient elevation of intracellular $Ca^{2+}$ levels through diverse G proteins such as $G{\alpha}_{q/11}$, $G{\alpha}_i$, $G{\alpha}_{12/13}$, and $G{\alpha}s$ and the related signal transduction pathway. In the present study, we examined LPA effects on $BK_{Ca}$ channel activity expressed in Xenopus oocytes, which are known to endogenously express the LPA receptor. Treatment with LPA induced a large outward current in a reversible and concentration-dependent manner. However, repeated treatment with LPA induced a rapid desensitization, and the LPA receptor antagonist Ki16425 blocked LPA action. LPA-mediated $BK_{Ca}$ channel activation was also attenuated by the PLC inhibitor U-73122, $IP_3$ inhibitor 2-APB, $Ca^{2+}$ chelator BAPTA, or PKC inhibitor calphostin. In addition, mutations in RCK1 and RCK2 also attenuated LPA-mediated $BK_{Ca}$ channel activation. The present study indicates that LPA-mediated activation of the $BK_{Ca}$ channel is achieved through the PLC, $IP_3$, $Ca^{2+}$, and PKC pathway and that LPA-mediated activation of the $BK_{Ca}$ channel could be one of the biological effects of LPA in the nervous and vascular systems.

• Microbiology and Biotechnology Letters
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• v.42 no.4
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• pp.354-360
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• 2014

In this study, the anti-obesity activity of Smilax china methanol extract (SCME) was evaluated using a pancreatic lipase enzyme inhibition assay, and a cell culture model system. Results indicated that, SCME effectively inhibited pancreatic lipase enzyme activity in a dose-dependent manner. Furthermore, SCME significantly suppressed insulin, dexamethasone, 3-isobutyl-1-methylxanthine-induced adipocyte differentiation, lipid accumulation, and triglyceride contents on 3T3-L1 preadipocytes, in a dose-dependent manner. The anti-adipogenic effect was modulated by cytidine-cytidine-adenosine-adenosine-thymidine (CCAAT)/enhancer binding proteins (C/EBP) ${\alpha}$, $C/EBP{\beta}$, and the peroxisome proliferator-activated receptor ${\gamma}$ gene and protein expressions. Moreover, SCME triggered lipolysis effects dose-dependently on adipocyte. Taken together, these results provide an important new insight into SCME, indicating that it possesses anti-obesity activity through pancreatic lipase inhibition, anti-adipogenic and lipolysis effects. SCME may therefore be utilized as a promising source in the field of nutraceuticals. The identification of active compounds that confer the anti-obesity activities of SCME may be a logical next step.

• Microbiology and Biotechnology Letters
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• v.42 no.3
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• pp.249-257
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• 2014

In this study, the anti-oxidative and anti-obesity activities of Amomum cardamomum L. methanol extract (ACME) were evaluated using DPPH radical scavenging activity assay, pancreatic lipase enzyme inhibition assay, and the cell culture model system. ACME exhibited DPPH radical scavenging activities dose-dependently, with $IC_{50}$ of DPPH radical scavenging activities of ACME being $25.15{\mu}g/ml$. Furthermore, ACME effectively suppressed pancreatic lipase enzyme activity dose-dependently. ACME also significantly suppressed adipocyte differentiation, lipid accumulation, triglyceride (TG) contents, and triggered lipolysis activity on 3T3-L1 preadipocytes in a dose-dependent manner, without cytotoxicity. Their anti-obesity effect was modulated by the cytidine-cytidine-adenosine-adenosine-thymidine (CCAAT)/enhancer binding proteins ${\alpha}$ ($C/EBP{\alpha}$), $C/EBP{\beta}$ and the peroxisome proliferator-activated receptor ${\gamma}$ ($PPAR{\gamma}$) gene and protein expressions. Taken together, these results provide an important new insight that A. cardamomum L. possesses anti-oxidative and anti-obesity activities such as pancreatic lipase inhibition, anti-adipogenic, and lipolysis effects. There is therefore potential for its use as a promising component in the field of nutraceuticals and the identification of the active compounds that confer the anti-oxidative and anti-obesity activities of ACME might be an appropriate next step.

• Archives of Pharmacal Research
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• v.26 no.10
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• pp.868-873
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• 2003

Ginsenosides, major active ingredients of Panax ginseng, that exhibit various pharmacological and physiological actions are transformed into compound K (CK) or M4 by intestinal microorganisms. CK is a metabolite derived from protopanaxadiol (PD) ginsenosides, whereas M4 is a metabolite derived from protopanaxatriol (PT) ginsenosides. Recent reports shows that ginsenosides might playa role as pro-drugs for these metabolites. In present study, we investigated the effect of bovine serum albumin (BSA), which is one of major binding proteins on various neurotransmitters, hormones, and other pharmacological agents, on ginsenoside $Rg_{2-}$, CK-, or M4-induced regulation of $\alpha3\beta4$ nicotinic acetylcholine (ACh) receptor channel activity expressed in Xenopus oocytes. In the absence of BSA, treatment of ACh elicited inward peak current ($I_{Ach}$) in oocytes expressing $\alpha3\beta4$ nicotinic ACh receptor. Co-treatment of ginsenoside $Rg_2$, CK, or M4 with ACh inhibited IAch in oocytes expressing $\alpha3\beta4$ nicotinic ACh receptor with reversible and dose-dependent manner. In the presence of 1% BSA, treatment of ACh still elicited $I_{Ach}$ in oocytes expressing $\alpha3\beta4$ nicotinic ACh receptor and co-treatment of ginsenoside $Rg_2$ or M4 but not CK with ACh inhibited $I_{Ach}$ in oocytes expressing $\alpha3\beta4$ nicotinic ACh receptor with reversible and dose-dependent manner. These results show that BSA interferes the action of CK rather than M4 on the inhibitory effect of $I_{Ach}$ in oocytes expressing $\alpha3\beta4$ nicotinic ACh receptor and further suggest that BSA exhibits a differential interaction on ginsenoside metabolites.

• The Korean Journal of Zoology
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• v.39 no.4
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• pp.378-386
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• 1996

We have developed a couple of new luciferase reporter plasmida with very low background reporter actlvltlea. One can be used to measure the promoter strength, after insertion of some promoter fragment into the reporter plasmid, and the other, with very low basal promoter actlvltlea, allis In studying eukaryotic transcriptional regulators. The latter reporter plasmid contains such cli elements as a 17 nucleotide long inftlator, Spl.blndIng sftes, GAL4 binding sltea, and bInding sitea for a certain Drosophila homeodomain proteins. In an attempt to construct an improved reporter plaimid by fadlltating transcriptional termination and minimizing any interference by cryptic promoters which may be preaent in the reporter pleamld DNA, we have inserted transsrlptional termination-related signals, a three tandem repeat of SV4O polyadenylatlon signal (AAA) and the putative transcrtptional termination signal (UMS) of the mouse c-mos gene, Into just upstream of the initIator, and the promoter actlvitiea were measured by a transIent expression assay employing the Drosophila Schneider line 2 cells. As expected, the basal promoter activitIes decreased maximally when both transcription termination related elements were inserted. Moreover, the reporter plasmld with the two elements allowed more sensitive measurement of transcriptional activation than the reporter piasmid without them. Theae reporter plasmids can be used for studying transcriptional regulators of higher organisms Including mammals as well as Droiophlla melanogaiter.