• Title/Summary/Keyword: inhibitory receptor

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Oncomodulin/Truncated Protamine-Mediated Nogo-66 Receptor Small Interference RNA Delivery Promotes Axon Regeneration in Retinal Ganglion Cells

  • Cui, Zhili;Kang, Jun;Hu, Dan;Zhou, Jian;Wang, Yusheng
    • Molecules and Cells
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    • v.37 no.8
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    • pp.613-619
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    • 2014
  • The optic nerve often suffers regenerative failure after injury, leading to serious visual impairment such as glaucoma. The main inhibitory factors, including Nogo-A, oligodendrocyte myelin glycoprotein, and myelin-associated glycoprotein, exert their inhibitory effects on axonal growth through the same receptor, the Nogo-66 receptor (NgR). Oncomodulin (OM), a calcium-binding protein with a molecular weight of an ~12 kDa, which is secreted from activated macrophages, has been demonstrated to have high and specific affinity for retinal ganglion cells (RGC) and promote greater axonal regeneration than other known polypeptide growth factors. Protamine has been reported to effectively deliver small interference RNA (siRNA) into cells. Accordingly, a fusion protein of OM and truncated protamine (tp) may be used as a vehicle for the delivery of NgR siRNA into RGC for gene therapy. To test this hypothesis, we constructed OM and tp fusion protein (OM/tp) expression vectors. Using the indirect immunofluorescence labeling method, OM/tp fusion proteins were found to have a high affinity for RGC. The gel shift assay showed that the OM/tp fusion proteins retained the capacity to bind to DNA. Using OM/tp fusion proteins as a delivery tool, the siRNA of NgR was effectively transfected into cells and significantly down-regulated NgR expression levels. More importantly, OM/tp-NgR siRNA dramatically promoted axonal growth of RGC compared with the application of OM/tp recombinant protein or NgR siRNA alone in vitro. In addition, OM/tp-NgR siRNA highly elevated intracellular cyclic adenosine monophosphate (cAMP) levels and inhibited activation of the Ras homolog gene family, member A (RhoA). Taken together, our data demonstrated that the recombinant OM/tp fusion proteins retained the functions of both OM and tp, and that OM/tp-NgR siRNA might potentially be used for the treatment of optic nerve injury.

Ginseng Saponins Prevent the Adverse Effect of Dependence-liable Drugs

  • Kim, Hack-Seang;Lim, Hwa-Kyung
    • Proceedings of the Ginseng society Conference
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    • 1998.06a
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    • pp.168-173
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    • 1998
  • A single administration of cocaine (CO), morphine (MOR) and methamphetamine (MA) showed hyperactivity in mice. Ginseng total saponin (GTS), ginsenosides Rbl and Rgl inhibited the hyperactivity induced by the drugs. The repeated administration of CO, MOR and MA showed the development of psychological dependence showing a.: the development of conditioned place preference (CPP) in mice and the development of dopamine (DA) receptor supersensitivity showing as sensitization of the drugs. GTS and Rgl inhibited the development of not only psychological dependence but also of DA receptor supersensitivity induced by CO and MA Rbl prevented also the development of psychological dependence and DA receptor supersensitivity induced by CO and MA but not by MOR. These results suggest that the development psychological dependence induced by the drugs is closely related with the development of DA receptor supersensitivity since both phenomena were inhibited by them. Apomorphine induced climbing behavior was also inhibited by G75 but not by both of Rbl and Rgl, indicating that GTS modulate dopaminergic action at both of pre and postsynaptic sites, but both of Rbl and Rgl , only at the presynaptic site. These results suggest that active components acting at the postsynaptic site exist in GTS. In this study, it was found that GTS, ginsenosides Rbl and Rgl inhibited tyrosine hydroxylase (TH) and these components exerted inhibitory effects on both Cal' currents and $\Delta$ Cm in rat adrenal chromaffin cells. These results suggest that G75 and ginsenosides regulate catecholamine synthesis and secretion. Meanwhile, it has been demonstrated that Rbl, at high doses has more powerful inhibition of cartecholamine secretion at the presynaptic site than Rbl. Therefore, it was presumed that inhibition of morphine induced psychological dependence by Rgl, but not by Rbl results from differences in the extent of this inhibitory action on dopaminergic synthesis and secretion.

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Sanguiin H-6 Blocks Endothelial Cell Growth through Inhibition of VEGF Binding to VEGF Receptor

  • Lee Sung-Jin;Lee Hak-Kyo
    • Archives of Pharmacal Research
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    • v.28 no.11
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    • pp.1270-1274
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    • 2005
  • The vascular endothelial growth factor (VEGF) plays a key role in angiogenesis, which is a process where new blood vessels develop from the endothelium of a pre-existing vasculature. VEGF exerts its activity by binding to its receptor tyrosine kinase, KDR/Flk-1, which is expressed on the surface of endothelial cells. A methanol extract and organic solvent (n-hexane, ethyl acetate, n-butanol, aqueous) fractions from Rubus coreanus were examined for their inhibitory effects on VEGF binding to the VEGF receptor. The methanol extract from the crude drug were found to significantly inhibit VEGF binding to the VEGF receptor ($IC_{50}$$\thickapprox$27 $\mu$g/mL). Among the fractions examined, the aqueous fraction from the medicinal plant showed potent inhibitory effects against the binding of KDR/Flk-1-Fc to immobilized $VEGF_{165}$ in a dose­dependent manner ($IC_{50}$$\thickapprox$11 $\mu$g/mL). Sanguiin H-6 was isolated as an active principle from the aqueous fraction, and inhibited the binding of KDR/Flk-1-Fc to immobilized $VEGF_{165}$ in a dose­dependent manner ($IC_{50}$$\thickapprox$0.3 $\mu$g/mL). In addition, sanguiin H-6 efficiently blocked the VEGF­induced HUVEC proliferation in a dose-dependent manner ($IC_{50}$$\thickapprox$7.4 $\mu$g/mL) but had no effect on the growth of HT1080 human fibrosarcoma cells. This suggests that sanguiin H-6 might be a potential anti-angiogenic agent.

Inhibitory actions of borneol on the substantia gelatinosa neurons of the trigeminal subnucleus caudalis in mice

  • Nguyen, Phuong Thao Thi;Jang, Seon Hui;Rijal, Santosh;Park, Soo Joung;Han, Seong Kyu
    • The Korean Journal of Physiology and Pharmacology
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    • v.24 no.5
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    • pp.433-440
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    • 2020
  • The substantia gelatinosa (SG) of the trigeminal subnucleus caudalis (Vc) is the first relay site for the orofacial nociceptive inputs via the thin myelinated Aδ and unmyelinated C primary afferent fibers. Borneol, one of the valuable time-honored herbal ingredients in traditional Chinese medicine, is a popular treatment for anxiety, anesthesia, and antinociception. However, to date, little is known as to how borneol acts on the SG neurons of the Vc. To close this gap, the whole-cell patch-clamp technique was applied to elucidate the antinociceptive mechanism responding for the actions of borneol on the SG neurons of the Vc in mice. In the voltage-clamp mode, holding at -60 mV, the borneol-induced non-desensitizing inward currents were not affected by tetrodotoxin, a voltage-gated Na+ channel blocker, 6-cyano-7-nitro-quinoxaline-2,3-dione, a non-N-methyl-ᴅ-aspartate (NMDA) glutamate receptor antagonist and DL-2-amino-5-phosphonopentanoic acid, an NMDA receptor antagonist. However, borneol-induced inward currents were partially decreased in the presence of picrotoxin, a γ-aminobutyric acid (GABA)A receptor antagonist, or strychnine, a glycine receptor antagonist, and was almost suppressed in the presence of picrotoxin and strychnine. Though borneol did not show any effect on the glycine-induced inward currents, borneol enhanced GABA-mediated responses. Beside, borneol enhanced the GABA-induced hyperpolarization under the current-clamp mode. Altogether, we suggest that borneol contributes in part toward mediating the inhibitory GABA and glycine transmission on the SG neurons of the Vc and may serve as an herbal therapeutic for orofacial pain ailments.

Inhibitory Effect of Bee Venom Toxin on the Growth of Cervix Cancer C33A Cells via Death Receptor Expression and Apoptosis

  • Ko, Seong Cheol;Song, Ho Sueb
    • Journal of Acupuncture Research
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    • v.31 no.2
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    • pp.75-85
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    • 2014
  • Objectives : We investigated whether bee venom(BV) inhibit cell growth through enhancement of death receptor expressions in the human cervix cancer C33A cells. Methods : BV($1{\sim}5{\mu}g/ml$) inhibited the growth of cervix cancer C33A cells by the induction of apoptotic cell death in a dose dependent manner. Results : Consistent with apoptotic cell death, expression of Fas, death receptor(DR) 3, 4, 5 and 6 was increased concentration dependently in the cells. Moreover, Fas, DR3 and DR6 revealed more sensitivity to BV. Thus, We reconfirmed whether they actually play a critical role in anti-proliferation of cervix cancer C33A cells. Consecutively, expression of DR downstream pro-apoptotic proteins including caspase-8, -3, -9 was upregulated and Bax was concomitantly overwhelmed the expression of Bcl-2. NF-${\kappa}B$ were also inhibited by treatment with BV in C33A cells. Conclusions : These results suggest that BV could exert anti-tumor effect through induction of apoptotic cell death in human cervix cancer C33A cells via enhancement of death receptor expression, and that BV could be a promising agent for preventing and treating cervix cancer.

Inhibitory Effect of $Mg^{2+}$ on the Release of $Ca^{2+}$ from Ryanodine Receptor of the Sarcoplasmic Reticulum in the Skeletal Muscle (골격근 망상체 $Ca^{2+}$유리 Channel[Raynodine receptor]의 $Mg^{2+}$에 의한 유리 억제)

  • 이철주
    • Journal of Chest Surgery
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    • v.25 no.4
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    • pp.347-355
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    • 1992
  • The precise mechanism of the Excitation-Contraction Coupling is still uncertain. But the concept that Ca2+ induced Ca2+ release [CICR] from the Ryanodine receptor in the sarcoplasmic reticulum [foot structure] may play a major role in E-C coupling has been widely accepted since 1970`s. It is believed that increased cytosolic Ca2+ followed by CICR is main contributor for E-C coupling of striated muscle. Resulting phenomena of ischemic /post-reperfusion myocyte is increased cytosolic Ca2+, even to the absence of Ca2+ in reperfusate. So intracellular inhibitor to CICR might prevent the ischemic and reperfusion damage of myocardial cells. The relatively purified foot protein, especially heavy sarcoplasmic reticulum rich, of the skeletal muscle was incorporated into the black lipid bilayer [Phosphatidyl ethanolamine: Phosphatidyl serine=l: 1]. Under the steady state of membrane potential [+20 mV], ionic current through Ryanodine receptor was measured with Cs+ as charge carrier. In the cis chamber [Cytoplasmic side], Mg2+ strongly inhibited CICR of Ryanodine receptor[Kd=6.2 nM]. In conclusion, naturally existing intracellular free Mg2+ can inhibit CICR from intracellular Ca2+ reservior [heavy SR]. So post-ischemic or post-reperfusing myocardium could be preserved using additional free Mg2+ in cardioplegic solution or reperfusate, otherwise the optimal concentration is undetermined.

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Inhibitory effect of Chaenomelis Fructus ethanol extract on receptor activator of nuclear factor-kappa B ligand-mediated osteoclastogenesis

  • Park, Geun Ha;Gu, Dong Ryun;Lee, Seoung Hoon
    • International Journal of Oral Biology
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    • v.45 no.1
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    • pp.15-24
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    • 2020
  • The fruit of Chaenomeles sinensis (Thouin) Koehne (Chaenomelis Fructus) known as "Mo-Gua" in Korea has been commonly used in traditional medicine to treat inflammatory diseases, such as sore throat. However, its effect on bone metabolism has not been elucidated yet. Here, we examined the effect of Chaenomelis Fructus ethanol extract (CF-E) on receptor activator of nuclear factor (NF)-κB ligand (RANKL)-mediated osteoclast differentiation and formation. CF-E considerably inhibited osteoclast differentiation and tartrate-resistant acid phosphatase-positive multinuclear cell formation from bone marrow-derived macrophages and osteoclast precursor cells in a dose-dependent manner. In addition, the formation of actin rings and resorption pits were significantly suppressed in CF-E-treated osteoclasts as compared with the findings in non-treated control cells. Consistent with these phenotypic inhibitory results, the expressions of osteoclast differentiation marker genes (Acp5, Atp6v0d2, Oscar, CtsK, and Tm7sf4) and Nfatc1, a pivotal transcription factor for osteoclastogenesis, were markedly decreased by CF-E treatment. The inhibitory effect of CF-E on RANKL-induced osteoclastogenesis was associated with the suppression of NFATc1 expression, not by regulation of mitogen-activated protein kinases and NF-κB activation but by the inactivation of phospholipase C gamma 1 and 2. These results indicate that CF-E has an inhibitory effect on osteoclast differentiation and formation, and they suggest the possibility of CF-E as a traditional therapeutic agent against bone-resorptive diseases, such as osteoporosis, rheumatoid arthritis, and periodontitis.

Ginsenoside F4 inhibits platelet aggregation and thrombus formation by dephosphorylation of IP3RI and VASP

  • Shin, Jung-Hae;Kwon, Hyuk-Woo;Lee, Dong-Ha
    • Journal of Applied Biological Chemistry
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    • v.62 no.1
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    • pp.93-100
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    • 2019
  • The root of Panax ginseng is used in ethnomedicine throughout eastern Asia and various recent studies have proved that Panax ginseng has inhibitory effects on cardiovascular disease. Each factor causing cardiovascular disease is known to have a very complex process which is achieved by a diverse number of mechanisms. Among these factors, platelets are the most important because they directly participate in thrombogenesis. Therefore, inhibiting the activity of platelets is an essential element for prevention of cardiovascular diseases. Our previous study showed the antiplatelet effects of Korean red ginseng extract and two of its components, ginsenoside Rg3 and ginsenoside Ro. However, the inhibitory mechanism of other ginsenosides remains unclear. Therefore, we investigated the inhibitory mechanism of ginsenoside F4 (G-F4) from Korean red ginseng on the regulation of signaling molecules involved in human platelet aggregation. With the use of G-F4, collagen-induced human platelet aggregation was inhibited in a dose-dependent manner, and it suppressed collagen-induced elevation of $[Ca^{2+}]_i$ mobilization through elevated phosphorylation of inositol 1, 4, 5-triphosphate receptor I ($Ser^{1756}$). In addition, G-F4 inhibited fibrinogen binding to ${\alpha}IIb/{\beta}_3$ during collagen-induced human platelet aggregation. Thus, in the present study, G-F4 showed an inhibitory effect on human platelet activation, suggesting its potential use as a new natural medicine for preventing platelet-mediated cardiovascular diseases.

Ameliorative effect of Abeliophyllum distichum Nakai on benign prostatic hyperplasia in vitro and in vivo

  • Choi, Young-Jin;Fan, Meiqi;Tang, Yujiao;Moon, Sangho;Lee, Seung-Hyun;Lee, Bokyung;Bae, Sung Mun;Lee, Sang Moo;Kim, Eun-Kyung
    • Nutrition Research and Practice
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    • v.16 no.4
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    • pp.419-434
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    • 2022
  • BACKGROUND/OBJECTIVES: Benign prostatic hyperplasia (BPH) is the most common prostate disease and one of the most common chronic diseases caused by aging in men. On the other hand, there has been no research on BPH using Abeliophyllum distichum Nakai (A. distichum). Therefore, this study investigated the effects of A. distichum on BPH. MATERIALS/METHODS: A. distichum leaves were extracted with distilled water, 70% ethanol, and 95% hexane as solvents. Subsequently, the inhibitory effects of each A. distichum extract on androgen receptor (AR) signaling were evaluated in vitro. The testosterone-induced BPH model was then used to confirm the efficacy of A. distichum leaves in 70% ethanol extract (ADLE). RESULTS: ADLE had the strongest inhibitory effect on AR signaling. A comparison of the activity of ADLE by harvest time showed that the leaves of A. distichum harvested in autumn had a superior inhibitory effect on AR signaling to those harvested at other times. In the BPH rat model, the administration of ADLE reduced the prostate size and prostate epithelial cell thickness significantly and inhibited AR signaling. Subsequently, the administration of ADLE also reduced the expression of growth factors, thereby inactivating the PI3K/AKT pathway. CONCLUSIONS: An analysis of the efficacy of ADLE to relieve BPH showed that the ethanol extract grown in autumn exhibited the highest inhibitory ability of the androgen-signaling related factors in vitro. ADLE also inhibited the expression of growth factors by inhibiting the expression of the androgen-signaling related factors in vivo. Overall, ADLE is proposed as a functional food that is effective in preventing BPH.

Lamotrigine, an antiepileptic drug, inhibits 5-HT3 receptor currents in NCB-20 neuroblastoma cells

  • Kim, Ki Jung;Jeun, Seung Hyun;Sung, Ki-Wug
    • The Korean Journal of Physiology and Pharmacology
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    • v.21 no.2
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    • pp.169-177
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    • 2017
  • Lamotrigine is an antiepileptic drug widely used to treat epileptic seizures. Using whole-cell voltage clamp recordings in combination with a fast drug application approach, we investigated the effects of lamotrigine on 5-hydroxytryptamine $(5-HT)_3$ receptors in NCB-20 neuroblastoma cells. Co-application of lamotrigine ($1{\sim}300{\mu}M$) resulted in a concentration-dependent reduction in peak amplitude of currents induced by $3{\mu}m$ of 5-HT for an $IC_{50}$ value of $28.2{\pm}3.6{\mu}M$ with a Hill coefficient of $1.2{\pm}0.1$. These peak amplitude decreases were accompanied by the rise slope reduction. In addition, $5-HT_3$-mediated currents evoked by 1 mM dopamine, a partial $5-HT_3$ receptor agonist, were inhibited by lamotrigine co-application. The $EC_{50}$ of 5-HT for $5-HT_3$ receptor currents were shifted to the right by co-application of lamotrigine without a significant change of maximal effect. Currents activated by 5-HT and lamotrigine co-application in the presence of 1 min pretreatment of lamotrigine were similar to those activated by 5-HT and lamotrigine co-application alone. Moreover, subsequent application of lamotrigine in the presence of 5-HT and 5-hydroxyindole, known to attenuate $5-HT_3$ receptor desensitization, inhibited $5-HT_3$ receptor currents in a concentration-dependent manner. The deactivation of $5-HT_3$ receptor was delayed by washing with an external solution containing lamotrigine. Lamotrigine accelerated the desensitization process of $5-HT_3$ receptors. There was no voltage-dependency in the inhibitory effects of lamotrigine on the $5-HT_3$ receptor currents. These results indicate that lamotrigine inhibits $5-HT_3$-activated currents in a competitive manner by binding to the open state of the channels and blocking channel activation or accelerating receptor desensitization.