• 한국발생생물학회지:발생과생식
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• 제15권1호
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• pp.31-39
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• 2011

Change in intracellular $Ca^{2+}$-concentration ($[Ca^{2+}]_i$) is an essential event for egg activation and further development. $Ca^{2+}$ ion is originated from intracellular $Ca^{2+}$-store via inositol 1,4,5-triphosphate receptor and/or $Ca^{2+}$ influx via $Ca^{2+}$ channel. This study was performed to investigate whether changes in $Ca^{2+}$/calmodulin dependent protein kinase II (CaM KII) activity affect $Ca^{2+}$ influx during artificial egg activation with ethanol using $Ca^{2+}$ monitoring system and whole-cell patch clamp technique. Under $Ca^{2+}$ ion-omitted condition, $Ca^{2+}$-oscillation was stopped within 30 min post microinjection of porcine sperm factor, and ethanol-induced $Ca^{2+}$ increase was reduced. To investigate the role of CaM KII known as an integrator of $Ca^{2+}$- oscillation during mammalian egg fertilization, CaM KII activity was tested with a specific inhibitor KN-93. In the eggs treated with KN-93, ethanol failed to induce egg activation. In addition, KN-93 inhibited inward $Ca^{2+}$ current ($I_{Ca}$) in a time-dependent manner in whole-cell configuration. Immunostaining data showed that the voltage-dependent $Ca^{2+}$ channels were distributed along the plasma membrane of mouse egg and 2-cell embryo. From these results, we suggest that $Ca^{2+}$ influx during fertilization might be controlled by CaM KII activity.

• Molecular & Cellular Toxicology
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• 제3권4호
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• pp.215-221
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• 2007

Neuronal cell toxicity induced by decreased nitric oxide (NO) production may be caused by modulation of constitutive neuronal NO synthase (nNOS). We used lead acetate ($Pb^{2+}$) to modulate physiological NO release and the related pathways of protein kinases like PKC, CaM-KII, and PKA in CATH.a cells, a dopaminergic cell line that has constitutive nNOS activity. In the cells treated with $Pb^{2+}$, cell viability and modulation (phosphorylation) levels of nNOS were determined by MTT assay and Western blot analysis, respectively. nNOS reductase activity (cytochrome c) was also assessed to compare the phosphorylation site-specific nNOS activity. nNOS activity was also determined by NADPH consumption rates. $Pb^{2+}$ treatment alone increased the phosphorylation of nNOS with decreased reductase activity. The phosphorylation levels increased markedly with decreased nNOS reductase activity, when $Pb^{2+}$ was combined with inhibitors for two (PKC and CaM-KII) or three (PKA, PKC and CaM-KII) protein kinases. Interestingly, when the cells were exposed to $Pb^{2+}$ plus PKC or CaM-KII inhibitor, the nNOS was phosphorylated strongly with the lowest activity. However, the levels of phosphorylated nNOS following $Pb^{2+}$ treatment decreased significantly after combined treatment with the PKA inhibitor, and $Pb^{2+}$-induced suppression of reductase activity did not occur. These results demonstrate that physiological NO release in the neuronal cells exposed to $Pb^{2+}$ can be decreased by PKA-mediated nNOS phosphorylation that may be caused by interactions with PKC and/or CaM-KII.

• The Korean Journal of Physiology and Pharmacology
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• 제14권5호
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• pp.331-336
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• 2010

In rapidly growing tumors, hypoxia commonly develops due to the imbalance between $O_2$ consumption and supply. Hypoxia Inducible Factor (HIF)-$1{\alpha}$ is a transcription factor responsible for tumor growth and angiogenesis in the hypoxic microenvironment; thus, its inhibition is regarded as a promising strategy for cancer therapy. Given that CamKII or PARP inhibitors are emerging anticancer agents, we investigated if they have the potential to be developed as new HIF-$1{\alpha}$-targeting drugs. When treating various cancer cells with the inhibitors, we found that a CamKII inhibitor, KN-62, effectively suppressed HIF-$1{\alpha}$ specifically in hepatoma cells. To examine the effect of KN-62 on HIF-$1{\alpha}$-driven gene expression, we analyzed the EPO-enhancer reporter activity and mRNA levels of HIF-$1{\alpha}$ downstream genes, such as EPO, LOX and CA9. Both the reporter activity and the mRNA expression were repressed by KN-62. We also found that KN-62 suppressed HIF-$1{\alpha}$ by impairing synthesis of HIF-$1{\alpha}$ protein. Based on these results, we propose that KN-62 is a candidate as a HIF-$1{\alpha}$-targeting anticancer agent.

• 한국수정란이식학회지
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• 제20권3호
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• pp.191-200
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• 2005

체외 배양 과정 중에 나타나는 생쥐 초기 2-세포 배의 "in vitro 2-cell block" 현상은 세포내 $Ca^{2+}$ 농도 변화와 밀접한 관련이 있다. 다양한 종류의 세포에서 acetylcholine은 세포막에 존재하는 muscarnic acetylcholine receptor를 통해 세포내 $Ca^{2+}$ 농도 증가를 유도한다. 본 실험에서는 생쥐 "in vitro 2-cell block" 현상에 있어서 ACh의 영향을 알아보기 위해 세포 내 $Ca^{2+}$ 농도 조절 물질을 처리한 후, 공초점 현미경을 이용하여 세포 내 $Ca^{2+}$ 농도 변화를 기록하였다. ACh은 세포 내에서 농도 의존적으로 $Ca^{2+}$ 농도 증가를 유도하며, "in Vitro 2-cell block" 현상을 극복하여 포배기로 발생을 유도하였다. ACh에 의한 $Ca^{2+}$ 농도 증가가 세포막에 존재하는 ACh receptor를 경유하여 나타나는 반응인지를 알아보기 위해 ACh receptor의 저해제인 atropine을 전처리한 결과, ACh에 의한 $Ca^{2+}$ 농도 증가가 완전히 저해되었다. 초기 2-세포 배에서 ACh이 결합하는 receptor의 종류를 확인하기 위하여 carbachol과 nicotin tartrate를 처리 하였다. Nicotinic AChR의 agonist인 nicotine tartrate 1 mM은 세포내 $Ca^{2+}$ 농도 증가를 보이지 않았다. 따라서 초기 2-세포 배의 세포막에는 muscarnic AChR가 기능적으로 작용함을 알 수 있다. ACh에 의한 세포내 $Ca^{2+}$ 농도 증가가 $Ca^{2+}$이 제거된 배양액에서도 나타나는 것으로 보아 ACh에 의한 세포내 $Ca^{2+}$ 변화는 주로 소포체와 같은 세포내 $Ca^{2+}$ 저장고로부터 분비됨을 알 수 있었다. 이러한 세포내 $Ca^{2+}$ 저장고로부터의 $Ca^{2+}$ 분비가 어떤 신호전달체계를 통해 나타나는 지를 조사하였다. 세포막의 PLC 저해제인 U73122를 전처리한 배는 ACh에 의한 $Ca^{2+}$ 농도 증가가 나타나지 않았으며, 세포 내 $Ca^{2+}$ 통로인 IP3R와 RyR의 저해제인 xestospongin과 heparin 혹은 dantrolene을 전처리한 결과 dantrolene에 의해 세포내 $Ca^{2+}$ 농도 증가가 억제되었다. 그리고 세포내 반복적인 $Ca^{2+}$ 농도 증가에 의해 활성도가 변화는 CaMKII의 작용을 확인하기 위하여 Ca MKII의 저해제인 KN-93을 전처리한 결과 $Ca^{2+}$ 농도 증가가 억제되는 것을 확인하였다. 이상의 결과로부터 ACh은 생쥐 초기 2-세포 배에서 ryano-dine receptor를 통하여 세포내 $Ca^{2+}$ 저장고로부터 $Ca^{2+}$ 분비를 유도하며, CaM KII에 의해서도 영향을 받는 것으로 보여진다. 생쥐 초기 2-세포 배에서 "in vitro 2-cell block"의 극복은 ACh에 의해 유도된 신호전달체계를 통해 세포내에 증가하는 $Ca^{2+}$ 농도 및 이에 따른 세포내 대사 작용의 활성화에 의하여 나타나는 것으로 생각된다.

• Molecular & Cellular Toxicology
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• 제4권1호
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• pp.16-21
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• 2008

Cell death of trophoblast, particularly by abnormal release of physiological nitric oxide (NO) has been known to be a causative factor of pre-eclampsia. In the present study, effects of intracellular calcium increase enhancing the activity of NO synthases (neuronal NO synthase, nNOS in this trophoblast cells) on the cell death were examined in a human placental full-term cell line (HT-1). Furthermore, we analyzed the possible mechanisms underlying the augmentation of $Ca^{++}$-mediated NOS activity mediated by protein kinases like PKC, PKA, or CaM-KII. In experiments for cell toxicity, a calcium ionophore (ionomycin $10{\mu}M$) enhanced cell death confirmed by MTT assay, and increased significantly nNOS activity determined with a hemoglobin oxidation assay. This cell death was partially protected by pre-treatment of 7-nitroindazole (7-NI, $10{\mu}M$ and $100{\mu}M$), a nNOS-specific inhibitor. Additionally, $Ca^{++}$-ionophore -induced increase of nNOS activity also was partially normalized by pre-treatment of specific inhibitors of protein kinases, PKC, PKA or CaM-KII. Therefore, we suggest that an increase of calcium influx, leading to the activation of nNOS activity, which in turn may result in the death of trophoblast cells by involvement of signaling mechanisms of protein kinases.

• 한국독성학회:학술대회논문집
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• 한국독성학회 2002년도 Molecular and Cellular Response to Toxic Substances
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• pp.188-189
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• 2002

This work aimed to identify neuronal cell toxicity induced by decrease of physiological NO production by differential phosphorylation of constitutive neuronal NO synthase (nNOS), which can be mediated by Ca2+-dependent PKC and/or CaM-KII activities activated by metals.(omitted)

• Bioinformatics and Biosystems
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• 제2권1호
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• pp.28-32
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• 2007

The protein phosphorylation is one of the important processes in the cell signaling pathway. A variety of protein kinase families are involved in this process, and each kinase family phosphorylates different kinds of substrate proteins. Many methods to predict the kinase-specific phosphoryrated sites or different types of phosphorylated residues (Serine/Threonine or Tyrosin) have been developed. We employed Supprot Vector Machine (SVM) to attempt the prediction of protein kinase specific phosphorylation sites. 10 different kinds of protein kinase families (PKA, PKC, CK2, CDK, CaM-KII, PKB, MAPK, EGFR) were considered in this study. We defined 9 residues around a phosphorylated residue as a deterministic instance from which protein kinases determine whether they act on. The subsets of PSI-BALST profile was converted to the numerical vectors to represent positive or negative instances. When SVM training, We took advantage of multiple SVMs because of the unbalanced training sets. Representative negative instances were drawn multiple times, and generated new traing sets with the same positive instances in the original traing set. When testing, the final decisions were made by the votes of those multiple SVMs. Generally, RBF kernel was used for the SVMs, and several parameters such as gamma and cost factor were tested. Our approach achieved more than 90% specificity throughout the protein kinase families, while the sensitivities recorded 60% on average.