• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2621-2625
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• 2009

To identify a non-acylguanidine NHE-1 inhibitor, an acylguanidne group was replaced with an imidazole group in the potent NHE-1 inhibitors with furan or benzothiphene core template, found from our previous studies. We synthesized and biologically evaluated 4-heteroaryl-2-amino-5-methylimidazole derivatives. All those imidazole compounds (16-18) represented the potent NHE-1 inhibitory activities, similar to the corresponding acylguanidine compounds.

• BMB Reports
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• v.47 no.7
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• pp.393-398
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• 2014

The role of Bax inhibitor-1 (BI-1) in the protective mechanism against apoptotic stimuli has been studied; however, as little is known about its role in death receptor-mediated cell death, this study was designed to investigate the effect of BI-1 on Fas-induced cell death, and the underlying mechanisms. HT1080 adenocarcinoma cells were cultured in high concentration of glucose media and transfected with vector alone (Neo cells) or BI-1-vector (BI-1 cells), and treated with Fas. In cell viability, apoptosis, and caspase-3 analyses, the BI-1 cells showed enhanced sensitivity to Fas. Fas significantly decreased cytosolic pH in BI-1 cells, compared with Neo cells, and this decrease correlated with BI-1 oligomerization, mitochondrial $Ca^{2+}$ accumulation, and significant inhibition of sodium-hydrogen exchanger (NHE) activity. Compared with Neo cells, a single treatment of BI-1 cells with the NHE inhibitor EIPA or siRNA against NHE significantly increased cell death, which suggests that the viability of BI-1 cells is affected by the maintenance of intracellular pH homeostasis through NHE.

• Proceedings of the Korean Society of Food Hygiene and Safety Conference
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• 2004.05a
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• pp.231-231
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• 2004

• Biomolecules & Therapeutics
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• v.19 no.4
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• pp.445-450
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• 2011

Preciously, we demonstrated that a novel NHE-1 inhibitor, KR-33028 attenuated cortical neuronal apoptosis induced by glutamate. In the present study, we investigated the signaling mechanism of neuroprotective effect of KR-33028 against glutamate-induced neuronal apoptosis, especially focusing on mitochondrial death pathway. Our data showed that glutamate induces a biphasic rise in mitochondrial $Ca^{2+}$ and that KR-33028 significantly prevents the second phase increase, but not the first phase increase in mitochondrial $Ca^{2+}$. Furthermore, KR-33028 restored the ${\Delta}{\Psi}_m$ dissipation and cytochrome c release into cytoplasm induced by glutamate in a concentration-dependent manner. The inhibition of mitochondrial $Ca^{2+}$ overload by ruthenium red also inhibited glutamate-induced apoptotic cell death, mitochondrial membrane potential, ${\Delta}{\Psi}_m$ dissipation and cytochrome c release. These data suggest that inhibition of mitochondrial $Ca^{2+}$ overload is likely to be attributable to anti-apoptotic effect of KR-33028. Taken together, our results suggest that anti-apoptotic effects of NHE-1 inhibitor, KR-33028 may be mediated through maintenance of mitochondrial function.

• The Korean Journal of Physiology and Pharmacology
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• v.20 no.6
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• pp.595-603
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• 2016

Ribosomal S6 kinase is a family of serine/threonine protein kinases involved in the regulation of cell viability. There are two subfamilies of ribosomal s6 kinase, (p90rsk, p70rsk). Especially, p90rsk is known to be an important downstream kinase of p44/42 MAPK. We investigated the role of p90rsk on ethanol-induced cell proliferation of HepG2 cells. HepG2 cells were treated with 10~50 mM of ethanol with or without ERK and p90rsk inhibitors. Cell viability was measured by MTT assay. The expression of pERK1, NHE1 was measured by Western blots. The phosphorylation of p90rsk was measured by ELISA kits. The expression of Bcl-2 was measured by qRT-PCR. When the cells were treated with 10~30 mM of ethanol for 24 hour, it showed significant increase in cell viability versus control group. Besides, 10~30 mM of ethanol induced increased expression of pERK1, p-p90rsk, NHE1 and Bcl-2. Moreover treatment of p90rsk inhibitor attenuated the ethanol-induced increase in cell viability and NHE1 and Bcl-2 expression. In summary, these results suggest that p90rsk, a downstream kinase of ERK, plays a stimulatory role on ethanol-induced hepatocellular carcinoma progression by activating anti-apoptotic factor Bcl-2 and NHE1 known to regulate cell survival.

• Journal of Food Hygiene and Safety
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• v.19 no.3
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• pp.161-166
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• 2004

We investigated the antiplatelet effect of a newly synthesized guanidine derivative KR-32558, a sodium-hydrogen exchanger-1 (NHE-1) inhibitor, together with the elucidation of the possible mechanisms of action. KR-32558 concentration -dependently inhibited the aggregation of washed rabbit platelets induced by collagen (10 ${\mu}g/ml$) with an $IC_{50}$ value of 85.9 ${\mu}M$, but with much weaker potency against aggregation induced by thapsigargin (0.5 ${\mu}M$) or A23187 (5 ${\mu}M$). And had no effect on platelet aggregation induced by arachidonic acid (100 ${\mu}M$), thrombin (0.05 U/ml) and U46619 (1 ${\mu}M$) up to 100 ${\mu}M$. KR-32558 completely inhibited the $[Ca^{2+}]_i$ mobilization induced by collagen at concentration of 100${\mu}iM$. Taken together, these observation suggest that KR-32558 selectively inhibited collagen-mediated platelet aggregation by blocking the cytoplasmic calcium mobilization in addition to NHE-1 inhibition.

• BMB Reports
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• v.49 no.4
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• pp.208-213
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• 2016

Prolonged ER stress (ERS) can be associated with the induction of apoptotic cell death in various heart diseases. In this study, we searched for microRNAs affecting ERS in the heart using in silico and in vitro methods. We found that miR-185 directly targets the 3′-untranslated region of Na⁺/H⁺ exchanger-1 (NHE-1), a protein involved in ERS. Cardiomyocyte ERS-triggered apoptosis induced by 100 ng/ml tunicamycin (TM) or 1 μM thapsigargin (TG), ERS inducers, was significantly reduced by miR-185 overexpression. Protein expression of pro-apoptotic markers such as CCAAT/enhancer-binding protein homologous protein (CHOP) and cleaved-caspase-3 was also markedly reduced by miR-185 in a dose-dependent manner. Cariporide (20 μM), a pharmacological inhibitor of NHE-1, also attenuated ERS-induced apoptosis in cardiomyocytes and CHOP protein expression, suggesting that NHE-1 plays an important role in ERS-associated apoptosis in cardiomyocytes. Collectively, the present results demonstrate that miR-185 is involved in cardio-protection against ERS-mediated apoptotic cell death.

• Archives of Pharmacal Research
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• v.29 no.5
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• pp.375-383
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• 2006

The anti platelet effects of a novel guanidine derivative, KR-32570 ([5-(2-methoxy-5-chlorophenyl) furan-2-ylcarbonyl]guanidine), were investigated with an emphasis on the mechanisms underlying its inhibition of collagen-induced platelet aggregation. KR-32570 significantly inhibited the aggregation of washed rabbit platelets induced by collagen $(10{\mu}g/mL)$, thrombin (0.05 U/mL), arachidonic acid $(100{\mu}M)$, a thromboxane (TX) $A_2$ mimetic agent U46619 (9,11-dideoxy-9,11-methanoepoxy-prostaglandin $F_2,\;1{\mu}M$) and a $Ca^{2+}$ ATPase inhibitor thapsigargin $(0.5{\mu}M)$ ($IC_{50}$ values: $13.8{\pm}1.8,\;26.3{\pm}1.2,\;8.5{\pm}0.9,\;4.3{\pm}1.7\;and\;49.8{\pm}1.4{\mu}M$, respectively). KR-32570 inhibited the collagen-induced liberation of $[^3H]$arachidonic acid from the platelets in a concentration dependent manner with complete inhibition being observed at $50{\mu}M$. The $TXA_2$ synthase assay showed that KR-32570 also inhibited the conversion of the substrate $PGH_2$ to $TXB_2$ at all concentrations. Furthermore, KR-32570 significantly inhibited the $[Ca^{2+}]_i$ mobilization induced by collagen at $50{\mu}M$, which is the concentration that completely inhibits platelet aggregation. KR-32570 also decreased the level of collagen $(10{\mu}g/mL)$induced secretion of serotonin from the dense-granule contents of platelets, and inhibited the NHE-1-mediated rabbit platelet swelling induced by intracellular acidification. These results suggest that the antiplatelet activity of KR-32570 against collagen-induced platelet aggregation is mediated mainly by inhibiting the release of arachidonic acid, $TXA_2$ synthase, the mobilization of cytosolic $Ca^{2+}$ and NHE-1.

• Biomolecules & Therapeutics
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• v.13 no.1
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• pp.20-25
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• 2005

The present study was performed to evaluate antiarrhythmic effects of KR-32570, a novel inhibitor of sodium hydrogen exchanger subtype-1 (NHE-1), in rat arrhythmia induced by focal ischemia and reperfusion. During ischemia, KR-32570 significantly decreased the number of premature ventricular contraction (PVC) from 152.0 times to 75.5, 52.4 and 20.0 times for 0.1, 0.3 and 1.0 mg/kg, respectively (p<0.05) and the duration of ventricular tachycardia (VT) from 88.1 s to 35.8, 7.7 and 1.3 s, respectively(p<0.05) in anesthetized rats subjected to 10-min coronary occlusion of coronary artery. Similarlt to ischemia-induced arrhythmia, KR-32570 significantly decreased reperfusion-induced arrhythmia including PVC (41.3, 21.5, 11.3 and 6.6 times at vehicle, 0.1, 0.3 and 1.0 mg/kg, respectively, p<0.05) and VT (100.5, 64.2, 25.8 and 25.2 s, respectively, p<0.05), and VF (86.9, 27.5, 6.9 and 0 s, respectively, p<0.05). Moreover, KR-32570 dose-dependently decreased the incidence of mortality occurring after reperfusion (41, 27, 18 and 0% at vehicle, 0.1, 0.3, 1.0 mg/kg, respectively). These results suggest that KR-32570 has a potent antiarrhythmic effect in rat arrhythmia induced by ischemia and reperfusion.