• Clinical and Experimental Reproductive Medicine
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• v.18 no.2
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• pp.181-187
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• 1991

Epidermal growth facter(EGF)는 내열성이 강하고 분자량이 6045 dalton인 단쇄상의 polypeptide로써, Cohen에 의해 생쥐의 악하선에서 처음 발견된 이래, 여러학자들에 의해 많은 연구가 되어왔다. 인체의 EGF는 urogastrone이라고도 불리우며, 인체의 소변에서 처음 검출되었고 분자구조 및 생리작용이 생쥐의 EGF와 매우 유사한 것으로 판명되었다. EGF의 자세한 작용기전은 확실히 규명되어있지는 않지만 세포의 증식과 분화를 촉진시키며 위산의 분비를 억제시킨다고 알려져 있다. 또한 EGF receptor는 분자량이 170,000${\sim}$180,000dalton인 세포표면의 polypeptide로써 인체, 쥐, 닭, 소 등의 세포막조직에 특이하게 결합되어 있다. 최근 수년동안 몇몇 학자들에 의해 EGF가 배아와 태아 및 태반의 성장을 촉진시키고 chorionic gonadotrophin과 placental lactogen의 분비를 증진하는데 기여할 것이라고 가정되어 왔다. 그러나 아직까지 배아착상에 대한 EGF의 작용여부에 관해서는 발표된 문헌이 없어 저자는 radioreceptor assay를 이용하여 EGF receptor binding과 토끼의 배아착상과의 관계를 규명하고자 임신경과에 따른 착상부위와 비착상부위의 자궁 및 태아측 태반과 모체측 태반을 분리취득하고 receptor binding assay를 시행하여 다음과 같은 결론을 얻었다. 1. 전임신군과 비임신군의 자궁조직의 membrane fraction으로부터 specific한 EGF receptor binding이 관찰되었다. 2. 착상전 임신 3일에 자궁조직의 EGF receptor수는 4.72 +0.16($10\;mol/{\mu}g$)로 비임신시보다 의의있게 증가되어 있었고(p<0.01), 착상시기인 임신 7일에는 착상된 부위에서 20.33+6.58로 훨씬 더 높은 측정치를 나타내었다(p<0.05). 3. 착상이후 가장 먼저 취득된 임신 14일의 태아측 태반은 모체측 태반의 1.39+0.49에 비해 훨씬 높은 11.94+1.97의 EGF receptor 측정치를 보였다 (p<0.01). 4. 이상의 소견들로 보아 EGF가 토끼의 배아착상에 밀접한 관련이 있을 것으로 추측되며, 이러한 착상전후의 EGF의 작용은 태아측으로부터 일 것으로 예상된다.

• BMB Reports
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• v.36 no.2
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• pp.207-213
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• 2003

Peroxisome proliferator-activated receptors (PPARs) are orphan nuclear hormone receptors that are known to control the expression of genes that are involved in lipid homeostasis and energy balance. PPARs activate gene transcription in response to a variety of compounds, including hypolipidemic drugs. Most of these compounds have high affinity to the ligand-binding domain (LBD) of PPARs and cause a conformational change within PPARs. As a result, the receptor is converted to an activated mode that promotes the recruitment fo co-activators such as the steroid receptor co-activator-1 (SRC-1). Based on the activation mechanism of PPARs (the ligand binding to $PPAR{\gamma}$ induces interactions of the receptor with transcriptional co-activators), we performed Western blot and ELISA. These showed that the indomethacin, a $PPAR{\gamma}$ ligand, increased the binding between $PPAR{\gamma}$ and SRC-1 in a ligand dose-dependent manner. These results suggested that the in vitro conformational change of $PPAR{\gamma}$ by ligands was also induced, and increased the levels of the ligand-dependent interaction with SRC-1. Collectively, we developed a novel and useful ELISA system for the mass screening of $PPAR{\gamma}$ ligands. This screening system (based on the interaction between $PPAR{\gamma}$ and SRC-1) may be a promising system in the development of drugs for metabolic disorders.

• Journal of Oriental Neuropsychiatry
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• v.15 no.1
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• pp.77-86
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• 2004

Objective : This study was performed to investigate the agonistic activity of Chunmajeongal-tang extract to the $GABA_A/benzodiazepine$ receptor complex. Methods : Male mice and Sprague-Dawley rats were used for this experiment. Chunmajeongal-tang Prescription was extracted with 80% methanol, evaporated in vacuo and dried with freeze dryer. The agonistic activity to the GABA/ benzodiazepine receptor complex and GABA transaminase activity were measured in vitro. Results : Chunmajeongal-tang extract inhibited dose-dependently the binding of [3H]Ro15-1788, an antagonist on GABA/benzodiazepine receptor complex, in rat cerebral cortices, showing $82.4{\pm}4.12%$ inhibition at a dose of 5.0 mg/kg. This extract inhibited dose-dependently the binding of [3H]flunitrazepam, an agonist on GABA/benzodiazepine receptor complex, in rat cerebral cortices, showing $5.6{\pm}1.24%$ inhibition. Furthermore, Chunmajeongal-tang extract inhibited the binding of [3H]flunitrazepam in the presence of GABA/NaCI with $13.2{\pm}0.44%$ inhibition, its inhibitory effect exhibited a positive GABA shift, which means that this extract activates a GABAergic neurotransmission.

• Korean Journal of Pharmacognosy
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• v.31 no.3
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• pp.273-279
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• 2000

Leukotriene $B_4\;(LTB_4)$ is a pro-inflammatory mediator synthesized in myeloid cells from arachidonic acid. Elevated levels of $LTB_4$ have been found in a number of inflammatory diseases and levels are related to disease activity in some of these. Because $LTB_4$ interacts with cells through specific cell surface receptors, $LTB_4$ receptor blockade is the most specific approach to reduce the pathogenic role of $LTB_4$. In order to find $LTB_4$ receptor antagonist from plants, we screened the $LTB_4$ receptor antagonistic activity of the methanol extract and solvent fractions of herbal drugs. The ability of samples to inhibit specific binding of $[^3H]-LTB_4$ to human peripheral neutrophils was used as assay to evaluate the antagonistic activity of plant materials. Among the tested methanol extracts of herbal drugs, Mori Radicis Cortex, Perillae Semen, Armeniacae Semen and Sophorae subprostratae Radix showed potent inhibitory activity above 70% at the concentration of $100\;{mu}g/ml$. The inhibitory activities of $LTB_4$ binding to human neutrophils were evaluated for several solvent fractions at three different concentrations. Especially, hexane soluble fractions of Anemarrhenae Rhizoma and Embeliae Radix, and ethyl acetate soluble fractions of Aristolochiae Fructus, Magnoliae Cortex and Zingiberis Rhizoma crudus showed moderate activity at $25\;{mu}g/ml$. These fractions were promising candidates for the study of the activity-guided chromatographic purification of active compounds. Silica gel column chromatography of hexane soluble fractions of Anemarrhenae Rhizoma and Embeliae Radix gave very active sub-fractions, AA-4 and ES-4, and their inhibition activities of $LTB_4$ binding to human neutrophil at $30\;{mu}g/ml$ were 78% and 62%, respectively. From these results we could anticipate new $LTB_4$ receptor antagonist from herbal drugs, and the block of $LTB_4$ effects may provide beneficial in neutrophil mediated diseases such as inflammation and bronchial asthma.

• Journal of Ginseng Research
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• v.17 no.1
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• pp.1-12
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• 1993

The Preventive effect of the saponin fraction of Panax ginseng C.A. Meyer against hyperchole- sterolemia was demonstrated by assaying the cholesterol and triacylglyceride level of the blood serum and liver of rats fed high-cholesterol diet with and/or without ginsenoside. To understand the mechanism of the preventive action of ginsenoside, ginsenoside effect on LDL receptor binding ability, cholesterol level, and cAMP level of Chinese hamster ovary (CHO) cells cultured under various conditions were examined. When LDL (20 $\mu$g/ml) was added to the culture medium for CHO cell culture, LDL receptor binding activity of the cell was suppressed down to 58% of that of normal group. Ginsenosides at 10--2% and 10-3% level (w/v) were shown to exert an appreciable stimulatory effect on CHO cell LDL receptor activity, which partially overcame the suppression due to the presence of LDL (20 $\mu\textrm{g}$/ml) in the medium. Ginsenosides also reduced the increased cholesterol level of test group almost to that of normal group, and it increased cAMP level, which was usually reduced to 55% of that of the normal group due to the presence of LDL in the medium. Comparison of Kd and Bmax value of CHO cells cultured under different conditions revealed that this stimulation was due not to the receptor's binding affinity but to its number. Addition of ginsenoside (10-2%) decreased the uptake of taurocholic acid as much as 20% at the actively transporting everted ileal sacs, but it failed to form a large mixed micelles with taurocholic acid, which was one of the proposed mechanisms by which ginsenoside inhibits bile acid reabsorption. From the above results, it seemed likely that ginsenoside prevented hypercholestrolemia by decreasing cholesterol level in cells thereby relieving the inhibition of LDL receptor synthesis by cholesterol and also by inhibiting bile acid reabsorption from the small intestine.

• Molecules and Cells
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• v.44 no.1
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• pp.1-12
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• 2021

The nuclear receptor peroxisome proliferator-activated receptor γ (PPARγ) is the master transcriptional regulator in adipogenesis. PPARγ forms a heterodimer with another nuclear receptor, retinoid X receptor (RXR), to form an active transcriptional complex, and their transcriptional activity is tightly regulated by the association with either coactivators or corepressors. In this study, we identified T-cell death-associated gene 51 (TDAG51) as a novel corepressor of PPARγ-mediated transcriptional regulation. We showed that TDAG51 expression is abundantly maintained in the early stage of adipogenic differentiation. Forced expression of TDAG51 inhibited adipocyte differentiation in 3T3-L1 cells. We found that TDAG51 physically interacts with PPARγ in a ligand-independent manner. In deletion mutant analyses, large portions of the TDAG51 domains, including the pleckstrin homology-like, glutamine repeat and proline-glutamine repeat domains but not the proline-histidine repeat domain, are involved in the interaction with the region between residues 140 and 506, including the DNA binding domain, hinge, ligand binding domain and activation function-2 domain, in PPARγ. The heterodimer formation of PPARγ-RXRα was competitively inhibited in a ligand-independent manner by TDAG51 binding to PPARγ. Thus, our data suggest that TDAG51, which could determine adipogenic cell fate, acts as a novel negative regulator of PPARγ by blocking RXRα recruitment to the PPARγ-RXRα heterodimer complex in adipogenesis.

• Journal of the East Asian Society of Dietary Life
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• v.15 no.3
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• pp.315-322
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• 2005

In this study we report on the estrogen activity of silkworm pupa and herb extracts in vitro. The estrogenic activity of these resources was investigated by competition binding assays with estrogen receptor $\alpha(ER{\alpha})\;or\;ER{\beta}$, and viability of MCF-7 cells, a human breast cancer cell line. Saturation ligand-binding analysis of $ER{\alpha}\;and\;ER{\beta}$ revealed that all plant extracts competed with estrogen ligand for binding to both ER subtypes with a similar preference and degree and competed stronger with ligand for binding to $ER{\beta}\;than\;to\;ER{\alpha}$. The highest $ER{\alpha}-binding$ sample was silkworm pupa aqueous extract The highest $ER{\beta}-binding$ sample was silkworm pupa oil. These samples were further tested for bioactivity based on their ability to regulate cell growth rate in ER(+) breast cancer cell line, MCF-7 cells. Our studies showed that silkworm pupa, soritae, sesame, yam, pueraria, malt, ginseng, Polygonum multiflorum, and Curcuma longa significantly stimulated the growth of MCF-7 cells (P<0.05). In summary, these results suggested that silkworm pupa and herbs might be useful as potential phytoestrogens.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.66-66
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• 2003

In skeletal muscle cells, depolarization of the transverse tubules (T-tubules) results in Ca$\^$2+/ release from the sarcoplasmic reticulum (SR), leading to elevated cytoplasmic Ca$\^$2+/ and muscle contraction. This process has been known as excitation-contraction coupling (E-C coupling). Several proteins, such as the ryanodine receptor (RyR), triadin, junctin, and calsequestrin (CSQ), have been identified to be involved in the Ca$\^$2＋/ release process. However, the molecular interactions between the SR proteins have not been resolved. In the present study, the mechanisms of interaction between RyRl and triadin have been studied by in vitro protein binding and $\^$45/Ca$\^$2+/ overlay assays. Our data demonstrate that the intraluminal loop II of RyR1 binds to triadin in Ca$\^$2+/-independent manner. Moreover, we could not find any Ca$\^$2+/ binding sites in the loop II region. GST-pull down assay revealed that a KEKE motif of triadin, which was previously identified as a CSQ binding site (Kobayasi et al.,2000 JBC) was also a binding site for RyR1. Our results suggest that the intraluminal loop II of RyR could participate in the RyR-mediated Ca$\^$2+/ release process by offering a direct binding site to luminal triadin.

• The Korean Journal of Physiology and Pharmacology
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• v.1 no.5
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• pp.485-493
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• 1997

We investigated the effect of ${\alpha}-adrenergic$ and cholinergic receptor agonists on $Ca^{2+}$ current in adult rat trigeminal ganglion neurons using whole-cell patch clamp methods. The application of acetylcholine, carbachol, and oxotremorine ($50\;{\mu}M\;each$) produced a rapid and reversible reduction of the $Ca^{2+}$ current by $17{\pm}6%,\;19{\pm}3%,\;and\;18{\pm}4%$, respectively. Atropine, a muscarinic antagonist, blocked carbachol- induced $Ca^{2+}$ current inhibition to $3{\pm}1%$. Norepinephrine ($50\;{\mu}M$) reduced $Ca^{2+}$ current by $18{\pm}2%$, while clonidine ($50\;{\mu}M$), an ${\alpha}2-adrenergic$ receptor agonist, inhibited $Ca^{2+}$ current by only $4{\pm}1%$. Yohimbine, an ${\alpha}2-adrenergic$ receptor antagonist, did not block the inhibitory effect of norepinephrine on $Ca^{2+}$ current, whereas prazosin, an ${\alpha}1-adrenergic$ receptor antagonist, attenuated the inhibitory effect of norepinephrine on $Ca^{2+}$ current to $6{\pm}1%$. This pharmacology contrasts with ${\alpha}2-adrenergic$ receptor modulation of $Ca^{2+}$ channels in rat sympathetic neurons, which is sensitive to clonidine and blocked by yohimbine. Our data suggest that the modulation of voltage dependent $Ca^{2+}$ channel by norepinephrine is mediated via an α1-adrenergic receptor. Pretreatment with pertussis toxin (250 ng/ml) for 16 h greatly reduced norepinephrine- and carbachol-induced $Ca^{2+}$ current inhibition from $17{\pm}3%\;and\;18{\pm}3%\;to\;2{\pm}1%\;and\;2{\pm}1%$, respectively. These results demonstrate that norepinephrine, through an ${\alpha}1-adrenergic$ receptor, and carbachol, through a muscarinic receptor, inhibit $Ca^{2+}$ currents in adult rat trigeminal ganglion neurons via pertussis toxin sensitive GTP-binding proteins.

• Microbiology and Biotechnology Letters
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• v.39 no.2
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• pp.140-145
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• 2011

Porcine epidemic diarrhea virus (PEDV) infection causes acute enteritis with lethal watery diarrhea resulting in a high mortality rate in piglets. As with the other members of group 1 coronaviruses, PEDV also utilizes the host aminopeptidase N (APN) as the major cellular receptor for entry into target cells. The coronavirus spike (S) protein is known to interact with the cellular surface for viral attachment and the S1 domain of all characterized coronaviruses contains a receptor-binding domain (RBD) that mediates a specific high-affinity interaction with their respective cellular receptors. Although the RBDs of several coronaviruses have been mapped, the location of the PEDV RBD has to date not been defined. As a first step toward the identification of the region of the S protein of the PEDV that is critical for recognition with the cellular receptor, we generated a series of S1-truncated variants and examined their abilities to bind to the porcine APN (pAPN) receptor. Our data indicate that the N-terminus of the S1 domain is required for pAPN association. The results from the present study may assist in our understanding of the molecular interactions between the PEDV S protein and the pAPN receptor.