• Journal of Ginseng Research
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• 제46권3호
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• pp.426-434
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• 2022

Aim: This study investigates the effects of ginsenoside Rb1 (GsRb1) on methamphetamine (METH)-induced toxicity in SH-SY5Y neuroblastoma cells and METH-induced conditioned place preference (CPP) in adult Sprague-Dawley rats. It also examines whether GsRb1 can regulate these effects through the NR2B/ERK/CREB/BDNF signaling pathways. Methods: SH-SY5Y cells were pretreated with GsRb1 (20 mM and 40 mM) for 1 h, followed by METH treatment (2 mM) for 24 h. Rats were treated with METH (2 mg/kg) or saline on alternating days for 10 days to allow CPP to be examined. GsRb1 (5, 10, and 20 mg/kg) was injected intraperitoneally 1 h before METH or saline. Western blot was used to examine the protein expression of NR2B, ERK, P-ERK, CREB, P-CREB, and BDNF in the SH-SY5Y cells and the rats' hippocampus, nucleus accumbens (NAc), and prefrontal cortex (PFC). Results: METH dose-dependently reduced the viability of SH-SY5Y cells. Pretreatment of cells with 40 µM of GsRb1 increased cell viability and reduced the expression of METH-induced NR2B, p-ERK, p-CREB and BDNF. GsRb1 also attenuated the expression of METH CPP in a dose-dependent manner in rats. Further, GsRb1 dose-dependently reduced the expression of METH-induced NR2B, p-ERK, p-CREB, and BDNF in the PFC, hippocampus, and NAc of rats. Conclusion: GsRb1 regulated METH-induced neurotoxicity in vitro and METH-induced CPP through the NR2B/ERK/CREB/BDNF regulatory pathway. GsRb1 could be a therapeutic target for treating METH-induced neurotoxicity or METH addiction.

• Journal of Microbiology and Biotechnology
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• 제15권4호
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• pp.756-766
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• 2005

The signaling mechanism underlying aburatubolactam C-induced FasL upregulation was investigated in human Jurkat T cells. After treatment with aburatubolactam C, the src-family PTKs $p56^{lck}\;and\;p59^{fyn}$, and MAP kinases ERK2 and JNK1, were activated prior to FasL upregulation; Both $p56^{lck}\;and\;p59^{fyn}$ were directly activated 2.4- and 2.2-fold, respectively, in vitro by aburatubolactam C. The aburatubolactam C-induced cellular changes, including the activation of ERK2 and INK1, and FasL upregulation, were completely prevented by the PTK inhibitor genistein. The activation of protein kinase C (PKC$\delta,\;\epsilon\;and\;\mu$ was also induced following aburatubolactam C treatment. Although the activation of $p56^{lck}$ and tyrosine phosphorylation of the cellular proteins were not blocked by the PKC inhibitor GFl09203X, the activation of ERK2 was completely abrogated, along with a detectably enhanced JNK1 activation; FasL upregulation, and apoptosis. However, the FasL upregulation and apoptosis were significantly inhibited by the PKC activator PMA, with a remarkable increase in the ERK2 activation. The cytotoxic effect of aburatubolactam C was reduced in the presence of the anti-Fas neutralizing antibody ZB-4. Although ectopic expression of Bcl-2 failed to completely block the cytotoxicity of aburatubolactam C, it was clearly suppressed. The c-Fos mRNA expression was upregulated in a biphasic manner, where the second phasic expression overlapped with the FasL upregulation. Accordingly, these results demonstrate that aburatubolactam C-induced apoptosis is exerted, at least in part, by FasL upregulation dictated by activation of the PTK ($p56^{lck}\;and\;p59^{fyn}$) /JNKI pathway, which is negatively affected by the concurrent activation of the PKC/ERK2 pathway proximal to PTK activation.

• 대한한의학회지
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• 제29권5호
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• pp.14-28
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• 2008

Objective : This study was carried out to understand effects of ginseng(hearinafter ; GS, Panax Ginseng) extract on regeneration responses on injured sciatic nerves in rats. Methods :Using white mouse, we damaged sciatic nerve & central nerve, and then applied GS to the lesion. Then we observed regeneration of axon and non-neuron. Results : 1. NF-200 protein immunostaining for the visualization of axons showed more distal elongation of sciatic nerve axons in GS-treated group than saline-treated control 3 and 7 days after crush injury. 2. GAP-43 protein was increased in the injured sciatic nerve and further increased by GS treatment. Enhanced GAP-43 protein signals were also observed in DRG prepared from the rats given nerve injury and GS treatment. 3. GS treatment in vivo induced enhanced neurite outgrowth in preconditioned DRG sensory neurons. In vitro treatment of GS on sensory neurons from intact DRG also caused increased neurite outgrowth. 4. Phospho-Erk1/2 protein levels were higher in the injured nerve treated with GS than saline. Phospho-Erk1/2 protein signals were mostly found in the axons in the injured nerve. 5. NGF and Cdc2 protein levels showed slight increases in the injured nerves of GS-treated group compared to saline-treated group. 6. The number of Schwann cell population was significantly increased by GS treatment in the injured sciatic nerve. GS treatment with cultured Schwann cells increased proliferation and Cdc2 protein signals. 7. GS pretreatment into the injured spinal cord generated increased astrocyte proliferation and oligodendrocytes in culture. In vitro treatment of GS resulted in more differentiated pericytoplasmic processes compared with saline treatment. 8. More arborization around the injury cavity and the occurrence at the caudal region of CST axons were observed in GS-treated group than in saline-treated group. Conclusion :GS extract may have the growth-promoting activity on regenerating axons in both peripheral and central nervous systems.

• Biomolecules & Therapeutics
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• 제20권1호
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• pp.57-61
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• 2012

The matrix metalloproteinase (MMP) family is involved in the breakdown of the extracellular matrix during normal physiological processes such as embryonic development, reproduction, and tissue remodeling, as well as in disease processes such as pathological aging, arthritis, and metastasis. Oxidative conditions generate reactive oxygen species (ROS) (e.g., hydrogen peroxide [$H_2O_2$]) in cells, which subsequently induce the synthesis of matrix metalloproteinase-1 (MMP-1). MMP-1, an interstitial collagenase, in turn stimulates an aging phenomenon. In this study, baicalein (5,6,7-trihydroxyfl avone) was investigated for its in vitro activity against $H_2O_2$-induced damage using a human skin keratinocyte model. Baicalein pretreatment signifi cantly inhibited $H_2O_2$-induced up-regulation of MMP-1 mRNA, MMP-1 protein expression and MMP-1 activity in cultured HaCaT keratinocytes. In addition, baicalein decreased the transcriptional activity of activator protein-1 (AP-1) and the expression of c-Fos and c-Jun, both components of the heterodimeric AP-1 transcription factor. Furthermore, baicalein reduced phosphorylation of extracellular signal-regulated kinase (ERK) and c-Jun-N-terminal kinase (JNK), which are upstream of the AP-1 transcription factor. The results of this study suggest that baicalein is involved in the inhibition of oxidative stress-induced expression of MMP-1 via inactivation of the ERK/JNK/AP-1 signaling pathway.

• 동의생리병리학회지
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• 제21권1호
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• pp.76-81
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• 2007

The effect of either low or high intensity four weeks exercise treadmill running on the activation of the extracellular-signal regulated protein kinase (ERK1/2) and the c-Jun N-terminal kinase(JNK) pathways was determined in rat tibialis muscle. Sprague-Dawley rats were assigned to one of three groups: (i) sedentary group(NE; n=10); (ii) low intensity exercise group (8m/min; LIE; n=10); and (iii) high intensity exercise group(28m/min; HIE; n=10). The training regimens were planned so that animals covered the same distance and had similar glycogenutilization for both LIE and HIE exercise sessions. After four weeks exercise, 48 h after the last exercise bout obtained samples. pERK1 increased 1.5 times comparing with the sedentary group in the low intensity group while it increased 11.7 times in high intensity group, in the tibialis of rats. In the low intensity group, pERK2 increased 1.4 times comparing with the sedentary group while it increased 3.3 times in high intensity group. While pJNK1 decreased 0.9 times, comparing with the sedentary group, pJNK2 was increased to 0.5 times in the low intensity group. But in high intensity group, pJNK2 decreased 0.7 times while pJNK1 didn't show any change. In conclusion, Four weeks exercise of different intensities results in tibialis muscle activation of intracellular signal pathways, which may be one mechanism regulating specific adaptations induced by different exercise intensities.

• Asian Pacific Journal of Cancer Prevention
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• 제13권12호
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• pp.6155-6157
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• 2012

Background: Mutations in the MAPK (Mitogen Activated Protein Kinase) signaling pathway - EGFR/Ras/RAF/MEK have been associated with the development of several carcinomas. ERK2, a downstream target of the MAPK pathway and a founding member of the MAPK family is activated by cellular signals emanating at the cell membrane. Activated ERK2 translocates into the nucleus to transactivate genes that promote cell proliferation. MKP - a dual specific phosphatase - interacts with activated ERK2 via the common docking (CD) domain of the later to inactivate (dephosphorylate) and effectively terminate further cell proliferation. A constitutively active form of ERK2 carrying a single point mutation - E322K in its CD domain, was earlier reported by our laboratory. In the present study, we investigated the prevalence of this CD domain E322K mutation in 88 well differentiated OSCC tissue samples. Materials and Method: Genomic DNA specimens isolated from 88 oral squamous cell carcinoma tissue samples were amplified with primers flanking the CD domain of the ERK2 gene. Subsequently, PCR amplicons were gel purified and subjected to direct sequencing to screen for mutations. Results: Direct sequencing of eighty eight OSCC samples identified an E322K CD domain mutation in only one (1.1%) OSCC sample. Conclusions: Our result indicates that mutation in the CD domain of ERK2 is rare in OSCC patients, which suggests the role of genetic alterations in other mitogenic genes in the development of carcinoma in the rest of the patients. Nevertheless, the finding is clinically significant, as the relatively rare prevalence of the E322K mutation in OSCC suggests that ERK2, being a common end point signal in the multi-hierarchical mitogen activated signaling pathway may be explored as a viable drug target in the treatment of OSCC.

• The Korean Journal of Physiology and Pharmacology
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• 제5권6호
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• pp.451-456
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• 2001

In rat hippocampus, kainic acid (KA; 10 mg/kg; i.p.) increased the phosphorylated forms of ERK1/2 (p-ERK1/2) and Jun kinase1 (p-JNK1), but not p-JNK2 and p38 (p-p38). The preadministration with cycloheximide (CHX; 5 mg/kg; i.p.) inhibited KA-induced increase of p-JNK1, but not p-ERK1/2. Surprisingly, the phosphorylated upstream MAP kinase kinases (p-MKKs) were not correlated with their downstream MAP kinases. The basal p-MKK1/2 levels were completely abolished by KA, which were reversed by CHX. In addition, p-MKK4 and p-MKK3/6 levels were enhanced by CHX alone, but were attenuated by KA. Thus, our results showed that KA increased the p-ERK and p-JNK levels in rat hippocampus, which were not parallel with their classical upstreamal kinases.

• Nutrition Research and Practice
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• 제13권4호
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• pp.279-285
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• 2019

BACKGROUND/OBJECTIVES: Excessive production of reactive oxygen species (ROS) such as hydroxyl (${\cdot}OH$), nitric oxide (NO), and hydrogen peroxide ($H_2O_2$) is reported to induce oxidative stress. ROS generated by oxidative stress can potentially damage glial cells in the nervous system. Cordyceps militaris (CM), a kind of natural herb widely found in East Asia. In this study, we investigated the free radical scavenging activity of the CM extract and its neuroprotective effects in $H_2O_2$-induced C6 glial cells. MATERIALS/METHODS: The ethanol extract of CM ($100-1,000{\mu}g/mL$) was used to measure DPPH, ${\cdot}OH$, and NO radical scavenging activities. In addition, hydrogen peroxide ($H_2O_2$)-induced C6 glial cells were treated with CM at $0.5-2.5{\mu}g/mL$ for measurement of cell viability, ROS production, and protein expression resulting from oxidative stress. RESULTS: The CM extract showed high scavenging activities against DPPH, ${\cdot}OH$, and NO radicals at concentration of $1,000{\mu}g/mL$. Treatment of CM with $H_2O_2$-induced oxidative stress in C6 glial cells significantly increased cell viability, and decreased ROS production. Cyclooxygenase-2 and inducible nitric oxide synthase protein expression was down-regulated in CM-treated groups. In addition, the protein expression level of phospho-p38 mitogen-activated protein kinase (p-p38 MAPK), phospho-c-Jun N-terminal kinase (p-JNK), and phospho-extracellular regulated protein kinases (p-ERK) in $H_2O_2$-induced C6 glial cells was down-regulated upon CM administration. CONCLUSION: CM exhibited radical scavenging activity and protective effect against $H_2O_2$ as indicated by the increased cell viability, decreased ROS production, down-regulation of inflammation-related proteins as well as p-p38, p-JNK, and p-ERK protein levels. Therefore, we suggest that CM could play the protective role from oxidative stress in glial cells.

• 생명과학회지
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• 제31권9호
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• pp.806-817
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• 2021

우울증 발생 기전에 신경가소성의 손상이 관여한다. Sirtuin 1은 신경가소성의 조절에 중요한 역할을 담당하고 있다. 또한 mTORC1 신호전달의 활성화가 신경가소성을 향상시키는 것으로 알려져 있다. 본 연구는 sirtuin 1이 mTORC1 신호전달을 통해 수상돌기 성장과 가시형성에 미치는지 영향을 조사하였다. 덱사메타손이 처치된 신경세포와 정상 배양 신경세포에 resveratrol (sirtuin 1 활성제)과 sirtinol (sirtuin 1 억제제)을 각각 처치하였다. Western blot 분석법을 사용하여, sirtuin 1 발현 및 ERK1/2, mTORC1, p70S6K의 인산화 양을 분석하였고, 면역형광측정법으로 수상돌기의 길이와 가시밀도를 분석하였다. Resveratrol은 덱사메타손 환경에서 농도 의존적으로 sirtuin 1의 발현을 증가시켰으며, ERK1/2 (sirtuin 1의 하위 타겟), mTORC1, 그리고 p70S6K (mTORC1의 하위 타겟)의 인산화를 유의하게 증가시켰다. 또한 resveratrol은 수상돌기 성장과 가시밀도를 증가시켰다. 반면, sirtinol은 정상 배양액에서 sirtuin 1의 발현을 유의하게 감소시켰으며, ERK1/2, mTORC1, p70S6K의 인산화 양을 농도 의존적으로 유의하게 감소시켰다. 또한 sitinol은 수상돌기 성장과 가시밀도를 유의하게 감소시켰다. 신경세포에 sirtuin 1의 siRNA를 transfection시켜 sirtuin 1을 knockdown 시켰을 때, ERK1/2 및 mTORC1의 인산화 양이 감소하였을 뿐만 아니라, 수상돌기 성장과 가시밀도도 감소하였다. 본 연구는 sirtuin 1이 ERK1/2-mTORC1 신호전달을 통해서 수상돌기 성장과 가시밀도를 변화시켜 신경가소성을 조절한다는 것을 보여주었다.

• The Korean Journal of Physiology and Pharmacology
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• 제8권4호
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• pp.187-194
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• 2004

Middle cerebral artery occlusion (MCAO) results in cell death by activation of complex signal pathways for cell death and survival. Hypothermia is a robust neuroprotectant, and its effect has often been attributed to various mechanisms, but it is not yet clear. Upstream from the cell death promoters and executioners are several enzymes that may activate several transcription factors involved in cell death and survival. In this study, we immunohistochemically examined the phosphorylation of mitogen-activated protein kinase, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and p38 kinase during early period of the ischemic injury, following 2 hours (h) of transient MCAO. Increased phosphorylation of ERK and p38 was observed in the vessels at 3 h, neuron-like cells at 6 and 12 h and glia-like cells at 12 h. Activation of JNK was not remarkable, and a few cells showed active JNK following ischemia. Phosphorylation of Elk-1, a transcription factor, was reduced by ischemic insult. Hypothermia attenuated the activation of ERK, p38 and JNK, and inhibited reduction of Elk-1. These data suggest that signals via different MAPK family members converge on the cell damage process and hypothermia protects the brain by interfering with these pathways.