• Development and Reproduction
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• v.4 no.1
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• pp.29-35
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• 2000

A phosphatidylinositol 3-kinase (PI3K) is a upstream component of insulin signaling by which protein synthesis can be stimulated in many systems. To elucidate involvement of PI3K and its downstream mammalian target of rapamycin (mTOR) in the insulin signaling in pleimplantation mouse embryos, 8-cell embryos were cultured to blastocysts in the presence or absence of insulin and／or inhibitor drugs. The number of blastomeres per blastocyst, protein synthesis, and protein phosphorylation were examined. There was significant difference in embryonic development to blastocyst stage and hatching was potentiated by the insulin supplementation. The increase in the mean celt numbers per blastocyst was apparent in the insulin culture. Wortmannin, a PI3K inhibitor and rapamycin, an inhibitor of mTOR abolished the stimulatory effect of insulin on morphological development mitosis and protein synthesis. In autoradiography, phosphoproteins pp22 and pp30 which undergo phosphorylation in response to insulin were identified. Taken together, it can be suggested that PI3K and mTOR engaged in insulin signaling in the mouse embryo 8-cell onward and mediate embryotropic offset of insulin.

• BMB Reports
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• v.29 no.6
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• pp.549-554
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• 1996

Phosphoinositide turnover in response to platelet-derived growth factor, epidermal growth factor, and bradykinin was evaluated in NIH 3T3 cells. Platelet-derived growth factor and bradykinin induced a significant increase in incorporation of $^{32}P$ into phosphatidylinositol (PI), phosphatidylinositol 4-monophosphate (PIP), and phosphatidylinositol 4.5-bisphosphate ($PIP_2$) in serum-starved NIH 3T3 cells. However, epidermal growth factor increased incorporation of $^{32}P$ into these phosphoinositides by only a small amount. Stimulation with platelet-derived growth factor, not bradykinin, caused a rapid elevation of PI and PIP kinase activities that were maximally activated within 10 min. The maximal levels of their elevation in cells with plateletderived growth factor stimulation were 3.2-fold for PI kinase, and 2.1-fold for PIP kinase. Short term pretreatment of NIH 3T3 cells with phorbol 12-myristate 13-acetate, activator of protein kinase C. caused an approximately 60% decrease in platelet-derived growth factor-induced PI kinase activities, indicating the feedback regulation of phosphoinositide turnover by protein kinase C. These results suggest that although the enhancement of phosphoinositide turnover is a rapidly occurring response in platelet-derived growth factor- or bradykinin-stimulated NIH 3T3 cells, phosphoinositide kinases may be associated with initial signal transduction pathway relevant to platelet-derived growth factor but not to bradykinin.

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.05a
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• pp.82-82
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• 2002

Expression of phase II detoxifying genes is regulated by Nrf2-mediated antioxidant response element (ARE) activation. We previously showed that phosphatidylinositol 3-kinase (PI3-kinase) plays an essential role in ARE-mediated rGSTA2 induction by oxidative stress.(omitted)

• Proceedings of the Korean Society of Toxicology Conference
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• 2002.11b
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• pp.142-142
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• 2002

Many studies have identified the phosphatidylinositol 3-kinase (PI3K) as a key regulator for various cellular functions including cell survival, growth and motility. We have previously shown that H-ras, but not N-ras, induces invasiveness and motility in human breast epithelial cells (MCF10A), while both H-ras and N-ras induce transformed phenotype.(omitted)

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.223.1-223.1
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• 2003

Many studies have identified the phosphatidylinositol 3-kinase (PI3K) as a key regulator for various cellular functions including cell survival, growth and motility. We have previously shown that H-ras, but not N-ras. induces invasiveness and motility in human breast epithelial cells (MCF10A), while both H-ras and N-ras induce transformed phenotype. In the present study, we wished to investigate the functional role of PI3K pathway in H-ra-induced invasive phenotype and motility of MCF10A cells. (omitted)

• Archives of Pharmacal Research
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• v.22 no.2
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• pp.108-112
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• 1999

Recombinant murine stem cell factor (rmSCF) or recombinant murine nerve growth factor (rmNGF) induced the morphological change of large numbers of rat peritoneal mast cells (RPMC). We investigated the role of phosphatidylinositol $3^{l}-kinase$ (PI3-kinase) in receptors-mediated morphological change in RPMC. Exposure of RPMC to PI3-kinase inhibitor, wortmannin, before the addition of rmSCF and rmNGF antagonized those factors-induced morphological change. These results suggest that the PI3-kinase is involved in the signal transduction pathway responsible for morphological change following stimulation of rmSCF and rmNGF and that wortmannin blocks these responses.

• BMB Reports
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• v.30 no.3
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• pp.182-187
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• 1997

The NADPH oxidase of phagocytes catalyzes the reduction of oxygen to $O_2^-$ at the expense of NADPH. The enzyme is dormant in resting neutrophils and becomes activated on stimulation. During activation, $p47^{phox}\;(\underline{ph}agocyte\;\underline{ox}idase\;factor)$, a cytosolic oxidase subunit, becomes extensively phosphorylated at a number of serines located between S303-S379. Oxidase activation can also be achieved by the addition of phosphorylated recombinant $p47^{phox}$ by protein kinase C in the cell-free system in the presence of $GTP{\gamma}S$. The cell-free activation is inhibited by wortmannin and LY294002. specific inhibitors of phosphatidylinositol 3kinase (PI 3-kinasel) These results indicate that PI 3-kinase may playa pivotal role in the activation of NADPH oxidase.

• Molecules and Cells
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• v.26 no.1
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• pp.48-52
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• 2008

We here demonstrate an anti-inflammatory action of raloxifene, a selective estrogen receptor modulator, in lipopolysaccharide (LPS)-induced murine macrophage RAW264.7 cells. Treatment with raloxifene at micromolar concentrations suppressed the production of nitric oxide (NO) by down-regulating expression of the inducible nitric oxide synthase (iNOS) gene in LPS-activated cells. The decreased expression of iNOS and subsequent reduction of NO were due to inhibition of nuclear translocation of transcription factor NF-${\kappa}B$. These effects were significantly inhibited by exposure to the phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor, LY294002, or by expression of a dominant negative mutant of PI 3-kinase. In addition, pretreatment with raloxifene reduced LPS-induced Akt phosphorylation as well as NF-${\kappa}B$ DNA binding activity and NF-${\kappa}B$-dependent reporter gene activity. Thus our findings indicate that raloxifene exerts its anti-inflammatory action in LPS-stimulated macrophages by blocking the PI 3-kinase-Akt-NF-${\kappa}B$ signaling cascade, and eventually reduces expression of pro-inflammatory genes such as iNOS.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2001.11a
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• pp.103-103
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• 2001

인간유방상피세포에서 H-ras가 침윤성과 세포 이동성을 유도한다는 것을 이 전연구에서 밝혔다. Phosphatidylinositol 3-kinase(PI3K)는 세포 이동성에서 중요한 역할을 하는 것으로 보고되고 있다. 본 연구에서 인간유방상피세포인 MCF10A에서 H-ras에 의해 유도된 침윤성에 PI3K가 어떠한 영향을 미치는지 살펴보고자 하였다. PI3K의 활성은 PI3K의 downstream molecule인 Akt의 인산화를 Western blot으로 확인하였다. Akt는 MCF10A, H-ras, N-ras MCF10A 세포에서 같은 정도로 발현되는 반면, 인산화된 Akt는 MCF10A 세포에 비해 H-ras MCF10A 세포와 N-ras MCF10A 세포에서 현저히 높게 나타났다. 이상의 결과로서 H-ras, N-ras 둘 다 PI3K를 활성화시키며, 침윤성과 세포이동성이 없는 N-ras MCF10A 세포에서도 PI3K가 활성화되었으므로, PI3K의 활성은 세포침윤성과 이동성을 유도하는데에 있어서 충분하지는 않음을 말해준다. PI3K의 저해제인 LY294002와 wortmannin을 세포에 처리하였을 때 세포침윤성과 이동성이 유의성 있게 감소되었다. 이상의 결과는 MCF10A 세포의 침윤성과 이동설에 있어서 PI3K의 활성이 충분하지는 않지만 반드시 필요하다는 것을 알 수 있었다.

• Molecular & Cellular Toxicology
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• v.4 no.3
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• pp.224-229
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• 2008

Eucommia ulmoides (Duchung) is commonly used for treatment of diabetes in Korean traditional medicine. However, the exact mechanism of its anti-diabetic effect has not yet been fully elucidated. In this study, the effect of E. ulmoides extract on glucose uptake was investigated in L6 rat skeletal muscle cells. E. ulmoides extract stimulated the activity of phosphatidylinositol (PI) 3-kinase that is a major regulatory molecule in glucose uptake pathway. Protein kinase B (PKB) and protein kinase C-${\xi}$ (PKC-${\xi}$), downstream mediators of PI 3-kinase, were also activated by E. ulmoides extract. We assessed the activity of AMP-activated protein kinase (AMPK), another regulatory molecule in glucose uptake pathway. Phosphorylation level of AMPK did not change with treatment of E. ulmoides extract. Phosphorylations of p38 mitogen activated protein kinase (p38 MAPK) and acetyl-CoA carboxylase (ACC), downstream mediators of AMPK, were not significantly different. Taken together, our results suggest that E. ulmoides may stimulate glucose uptake through PI 3-kinase but not AMPK in L6 skeletal muscle cells.