• 생물정신의학
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• 제20권4호
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• pp.159-165
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• 2013

Objectives Mechanisms of clinical synergistic effects, induced by co-treatments of lithium and valproate, are unclear. Extracellular signal-regulated kinase (ERK) has been suggested to play important roles in mechanisms of the action of mood stabilizers. In this study, effects of co-treatments of lithium and valproate on the ERK1/2 signal pathway and its down-stream transcription factors, ELK1 and C-FOS, were investigated in vitro. Methods PC12 cells, human pheochromocytoma cells, were treated with lithium chloride (30 mM), valproate (1 mM) or lithium chloride + valproate. The phosphorylation of ERK1/2 was analyzed with immunoblot analysis. Transcriptional activities of ELK1 and C-FOS were analyzed with reporter gene assay. Results Single treatment of lithium and valproate increased the phosphorylation of ERK and transcriptional activities of ELK1 and C-FOS, respectively. Combined treatments of lithium and valproate induced more robust increase in the phosphorylation of ERK1/2 and transcriptional activities of ELK1 and C-FOS, compared to those in response to single treatment of lithium or valproate. Conclusions Co-treatments of lithium and valproate induced synergistic increase in the phosphorylation of ERK1/2 and transcriptional activities of its down-stream transcription factors, ELK1 and C-FOS, compared to effects of single treatment. The findings might suggest potentiating effects of lithium and valproate augmentation treatment strategy.

• 한국발생생물학회지:발생과생식
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• 제24권2호
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• pp.113-123
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• 2020

Metformin has been widely used as an antidiabetic drug, and reported to inhibit cell proliferation in many cancers including non-small cell lung cancer (NSCLC). In NSCLC cells, metformin suppresses PI3K/AKT/mTOR signaling pathway, but effect of metformin on RAS/RAF/MEK/ERK signaling pathway is controversial; several studies showed the inhibition of ERK activity, while others demonstrated the activation of ERK in response to metformin exposure. Metformin-induced activation of ERK is therapeutically important, since metformin could enhance cell proliferation through RAS/RAF/MEK/ERK pathway and lead to impairment of its anticancer activity suppressing PI3K/AKT/mTOR pathway, requiring blockade of both signaling pathways for more efficient antitumor effect. The present study tested the combination therapy of metformin and trametinib by monitoring the alterations of regulatory effector proteins of cell signaling pathways and the effect of the combination on cell viability in NCI-H2087 NSCLC cells with NRAS and BRAF mutations. We show that metformin alone blocks PI3K/AKT/mTOR signaling pathway but induces the activation and phosphorylation of ERK. The combination therapy synergistically decreased cell viability in treatment with low doses of two drugs, while it gave antagonistic effect with high doses. These findings suggest that the efficacy of metformin and trametinib combination therapy may depend on the alteration of ERK activity induced by metformin and specific cellular context of cancer cells.

• The Korean Journal of Physiology and Pharmacology
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• 제18권4호
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• pp.353-358
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• 2014

Control of blood pressure is maintained by the interaction between the arterial baroreflex and vestibulosympathetic reflex during postural changes. In this study, the contributions of vestibular receptors and baroreceptors to the maintenance of blood pressure following acute hypotension were compared in terms of phosphorylated extracellular regulated protein kinase (pERK) expression in the nucleus tractus solitaries (NTS). Expression of pERK in the NTS was measured in conscious rats that had undergone bilateral labyrinthectomy (BL) and/or sinoaortic denervation (SAD) 5, 10, 20, and 40 min following acute hypotension induced by sodium nitroprusside (SNP) infusion. Expression of pERK increased significantly in the NTS in the control group following SNP infusion, and the expression peaked at 10 min after SNP infusion. The number of pERK positive neurons increased following SNP infusion in BL, SAD, and BL+SAD groups, although the increase was smaller than in control group. The BL group showed a relatively higher reduction in pERK expression than the SAD group, and the pERK expression in the NTS was localized to the caudal portion of the nuclei in the BL and SAD groups. These results suggest that the vestibular receptors may play a key role in maintaining blood pressure following acute hypotension; thus, the vestibular system may contribute to compensate for orthostatic hypotension.

• Journal of Photoscience
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• 제9권2호
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• pp.433-435
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• 2002

In the present study, we investigated the actions of sphingosine-I-phosphate (SPP) in Mel-Ab melanocytes. We observed the cytoprotective effect of SPP on UVB-induced cell death. Following exposure of cells to UVB, a significant protective effect was seen in cultures pretreated with SPP. Since SPP is well known as a mitogenic agent, it is possible that the mitogenic effect of SPP may contribute to cell survival. Surprisingly, we found that SPP inhibited DNA-synthesis significantly. We were next interested in the regulation of the extracellular signal-regulated protein kinase (ERK) and Akt pathways by SPP. We clearly observed that SPP potently stimulated the phosphorylation of both ERK and Akt against UVB-induced cell death. Based on these results, we conclude that SPP may show its cytoprotective effect through ERK and Akt activation.

• 대한의생명과학회지
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• 제17권4호
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• pp.291-295
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• 2011

PD98059 is the specific inhibitor of extracellular signaling-regulated kinase (ERK) kinase (MEK). ERK is involved in a mitogen-activated protein kinase (MAPK) cascade controlling cell growth and differentiation. Although the inhibition of ERK is known to induce cell death in various cell lines, this effect is still controversial and the role of PD98059 on the death of HeLa $S_3$ cells, a subclone of the cervical cancer cell line, is not well understood. The apoptosis of HeLa $S_3$ cells increased after the treatment of 50 ${\mu}M$ PD98059. The induction of apoptosis by PD98059 was occurred in a time- and a dose-dependent manners. The expression of Bcl-2 was reduced in accordance with decrease of ERK2 expression. Taken together, these results indicate that PD98059 has a cytotoxicity in HeLa $S_3$ cells and it may be used as a potential target for the treatment of cervical cancer.

• 한국약용작물학회지
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• 제16권3호
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• pp.183-187
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• 2008

Nerve injury can lead to neuropathic pain, which is often resistant to current analgesics and interventional therapeutic methods. Extracellular signal-regulated kinase (ERK) plays important role in the induction of neuropathic pain. We explored the antinociceptive effect of curcumin and its effect on ERK in the spinal cord in the neuropathic pain model of rats induced by chronic constriction injury (CCI) of the sciatic nerve. In injured rats, mechanical allodynia, which is one of characteristics of neuropathic pain developed and the activation of ERK in spinal cord significantly increased compared with control group. However, administration of curcumin (50 mg/kg/day p.o) for 7 days started from one day before the injury prevented the development of mechanical allodynia and increase of ERK phosphorylation. These results indicate that curcumin can be a new therapeutic agent in the treatment of neuropathic pain.

• Childhood Kidney Diseases
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• 제21권1호
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• pp.1-7
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• 2017

Mitogen-activated protein kinases (MAPKs) play important roles in various cellular functions including proliferation, differentiation, and apoptosis. We showed that MAPKs are developmentally regulated in the rat kidney. p38 MAPK (p38) and extracellular signal-regulated kinase (ERK) were strongly expressed in the fetal kidney, whereas c-Jun N-terminal kinase (JNK) was detected predominantly in the adult kidney. The inhibition of p38 or ERK in organ culture resulted in reduced nephron formation with or without reduced kidney size. On the other hand, persistent fetal expression pattern of MAPKs, i.e., upregulation of p38 and ERK and downregulation of JNK, was observed in the cyst epithelium of human renal dysplasia, ovine fetal obstructive uropathy, and pcy mice, a model of polycystic kidney disease. Furthermore, activated p38 and ERK induced by cyclic stretch mediated proliferation and $TGF-{\beta}1$ expression in ureteric bud cells, probably leading to cyst formation and dysplastic changes. Inhibition of ERK slowed the disease progression in pcy mice. Finally, ERK and p38 were inactivated in the early embryonic kidney subjected to maternal nutrient restriction, characterized by reduced ureteric branching and nephron number. Thus, MAPKs mediate the development of normal and diseased kidney. Their modulation may result in novel therapeutic strategies against developmental abnormalities of the kidney.

• 동의생리병리학회지
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• 제24권5호
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• pp.872-876
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• 2010

The present study found that EA pre-treatment effectively attenuated both spinal ERK activation and hyperalgesia against carrageenan-induced inflammation, whereas EA co-treatment with carrageenan injection unexpectedly elevated ERK activation in a synergistic manner and virtually had no analgesic effect. Therefore, we have concluded that the molecular mechanism of EA anagesia may be related to the inhibition of spinal ERK activation. Further experiments are required to find the intermediate candidates which transmits the pain-alleviating signals on the way of inhibiting ERK activation by EA.

• BMB Reports
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• 제45권12호
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• pp.724-729
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• 2012

In this study, we evaluated the anti-melanogenesis effects of Caffeoylserotonin (CaS) in B16 melanoma cells. Treatment with CaS reduced the melanin content and tyrosinase (TYR) activity in B16 melanoma cells in a dose-dependent manner. CaS inhibited the expression of melanogenesis-related proteins, including microphthalmia-associated transcription factor (MITF), TYR, and tyrosinase-related protein-1 (TRP-1), but not TRP-2. ${\alpha}$-MSH is known to interact with melanocortin 1 receptor (MC1R) thus activating adenylyl cyclase and increasing intracellular cyclic AMP (cAMP) levels. Furthermore, cAMP activates extracellular signal-regulated kinase 2 (ERK2) via phosphorylation, which phosphorylates MITF, thereby targeting the transcription factor to proteasomes for degradation. The CaS reduced intracellular cAMP levels to unstimulated levels and activated ERK phosphorylation within 30 min. The ERK inhibitor PD98059 abrogated the suppressive effect of CaS on ${\alpha}$-MSH-induced melanogenesis. Based on this study, the inhibitory effects of CaS on melanogenesis are derived from the downregulation of MITF signaling via the inhibition of intracellular cAMP levels, as well as acceleration of ERK activation.

• 약학회지
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• 제51권5호
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• pp.350-354
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• 2007

Taurine has been shown to be tissue-protective against oxidant-induced injury and is a powerful regulator of the immune system. However, there is no study on the antimelanogenic effect of taurine. In this study, we investigated the whitening effect of taurine in B16F10 mouse melanoma cells. Cell viability was measured by MTT assay. We examined melanin contents and tyrosinase activity according to time and concentration. Extracellular signal regulated kinase (ERK) is an important regulator of melanogenesis. It has been reported that activated ERK induced microphthalmia associated transcription factor (MITF) phosphorylation and its subsequent degradation and thus reduced melanin synthesis. In our B16F10 cell culture system, taurine led to decrease melanin contents by 21% at 48 hr. We then observed taurine effects on ERK-P, MITF and tyrosinase by Western blot. ERK was activated at 18 hr and 24 hr, whereas MITF reduced. We could not observe any differences in the levels of tyrosinase. These results suggested that taurine inhibited melanogenesis by ERK signal pathway via MITF degradation. We expect that taurine has potential skin whitening agents in cosmetics.