• Proceedings of the Korean Society of Applied Pharmacology
• /
• 2003.11a
• /
• pp.84-84
• /
• 2003

Lead has long been considered as a toxic environmental pollutant, which severely damages central nervous system. Lead can cause hypo- and de-myelination, and glial cells are closely related with myelination or demyelination. Matrix metalloproteinases (MMPs) are proteolytic enzymes that are involved in the remodelling of the extracellular matrix in a variety of physiological and pathological processes. MMPs also seem to be important in the pathogenesis of inflammatory demyelinating diseases of the central and peripheral nervous system. In this study, we investigated whether lead affects MMP-9 expression in rat primary glial cells. Treatment of 0.1-5 ${\mu}$M lead dose- and time-dependently increased MMP-9 expression in rat primary glial cells. The activity of MMPs was determined using zymography. Lead activated Erk(1/2) but neither of the other endogenous MAP kinases, p38 or JNK. Inhibition of Erk(1/2) activation by PD98059, a MEK inihibitor, prevented lead-induced expression of MMP-9. The results of the present study suggest that lead intoxication may adversely affect brain function at least in part by inducing MMP-9 expression through Erk(1/2) activation in primary glial cells.

• Biomolecules & Therapeutics
• /
• v.32 no.3
• /
• pp.361-367
• /
• 2024

In this study, we investigated the efficacy of kaempferol (a flavonoid found in plants and plant-derived foods such as kale, beans, tea, spinach and broccoli) on vascular contractibility and aimed to clarify the detailed mechanism underlying the relaxation. Isometric contractions of divested muscles were stored and linked with western blot analysis which was carried out to estimate the phosphorylation of myosin phosphatase targeting subunit 1 (MYPT1) and phosphorylation-dependent inhibitory protein for myosin phosphatase (CPI-17) and to estimate the effect of kaempferol on the RhoA/ROCK/CPI-17 pathway. Kaempferol conspicuously impeded phorbol ester-, fluoride- and a thromboxane mimetic-derived contractions regardless of endothelial nitric oxide synthesis, indicating its direct effect on smooth muscles. It also conspicuously impeded the fluoride-derived elevation in phospho-MYPT1 rather than phospho-CPI-17 levels and phorbol 12,13-dibutyrate-derived increase in phospho-CPI-17 and phospho-ERK1/2 levels, suggesting the depression of PKC and MEK activities and subsequent phosphorylation of CPI-17 and ERK1/2. Taken together, these outcomes suggest that kaempferol-derived relaxation incorporates myosin phosphatase retrieval and calcium desensitization, which appear to be modulated by CPI-17 dephosphorylation mainly through PKC inactivation.

• Biomolecules & Therapeutics
• /
• v.18 no.4
• /
• pp.442-447
• /
• 2010

This study was conducted to determine whether treatment with the anti-inflammatory eupatilin influences intestinal smooth muscle contraction stimulated by carbachol and, if so, to investigate the related mechanism. Denuded ileal or colonic muscles from Sprague-Dawley rats were used for the study and measurements of isometric contractions were obtained using a computerized data acquisition system; this data was also combined with results from molecular experiments. Eupatilin from Artemisia asiatica Nakai significantly decreased carbachol-induced contractions in both ileal and colonic muscles. Interestingly, eupatilin decreased carbachol-induced phosphorylation of ERK1/2 more significantly than that of MYPT1 at Thr855 in ileal and colonic muscles. However, eupatilin significantly decreased phosphorylation of MYPT1 at Thr855, but only in ileal muscle. Therefore, thin filament regulation, including MEK inactivation and related phospho-ERK1/2 decrease, is mainly involved in the eupatilin-induced decrease of intestinal contraction induced by carbachol. In conclusion, this study provides the evidence and a possible related mechanism concerning the inhibitory effect of the flavonoid as an antispasmodic on the agonist-induced contractions in rat ileum and colonic muscles.

• BMB Reports
• /
• v.54 no.5
• /
• pp.272-277
• /
• 2021

RalBP1 associated EPS domain containing 1 (REPS1) is conserved from Drosophila to humans and implicated in the endocytic system. However, an exact role of REPS1 remains largely unknown. Here, we demonstrated that mitogen activated protein kinase kinase (MEK)-p90 ribosomal S6 Kinase (RSK) signaling pathway directly phosphorylated REPS1 at Ser709 upon stimulation by epidermal growth factor (EGF) and amino acid. While REPS2 is known to be involved in the endocytosis of EGF receptor (EGFR), REPS1 knockout (KO) cells did not show any defect in the endocytosis of EGFR. However, in the REPS1 KO cells and the KO cells reconstituted with a non-phosphorylatable REPS1 (REPS1 S709A), the recycling of transferrin receptor (TfR) was attenuated compared to the cells reconstituted with wild type REPS1. Collectively, we suggested that the phosphorylation of REPS1 at S709 by RSK may have a role of the trafficking of TfR.

• BMB Reports
• /
• v.46 no.12
• /
• pp.617-622
• /
• 2013

Rac1 plays a key role in neurite outgrowth via reorganization of the actin cytoskeleton. The molecular mechanisms underlying Rac1-mediated actin dynamics in the cytosol and plasma membrane have been intensively studied, but the nuclear function of Rac1 in neurite outgrowth has not yet been addressed. Using subcellular fractionation and immunocytochemistry, we sought to explore the role of nuclear Rac1 in neurite outgrowth. bFGF, a strong agonist for neurite outgrowth in PC12 cells, stimulated the nuclear accumulation of an active form of Rac1. Rac1-PBR (Q) mutant, in which six basic residues in the polybasic region at the C-terminus were replaced by glutamine, didn't accumulate in the nucleus. In comparison with control cells, cells expressing this mutant form of Rac1 displayed a marked defect in extending neurites that was concomitant with reduced expression of MAP2 and MEK-1. These results suggest that Rac1 translocation to the nucleus functionally correlates with bFGF-induced neurite outgrowth.

• Journal of Applied Biological Chemistry
• /
• v.65 no.2
• /
• pp.93-99
• /
• 2022

Lysosome organelle extract (LOE) was derived from egg whites. The lysosome is an intracellular organelle that contains several hydrolysis enzymes. Previous studies have reported that LOE performs important functions, such as melanin de-colorization and anti-melanin production in B16F10 melanoma cells. However, its principal molecular and cellular mechanisms have not been elucidated till date. In non-cytotoxic conditions, LOE significantly inhibited α-MSH induced melanin synthesis of murine B16F10 cells. The anti-melanogenic activity of LOE was mediated by suppressing the mRNA expression of tyrosinase enzyme, tyrosinase related protein-1/2 (TRP-1/2), and microphthalmia-associated transcription factor (MITF) genes. By performing western blot analysis, we found that LOE significantly attenuated melanogenesis. In this case, LOE helped in increasing extracellular receptor kinase (ERK) phosphorylation in α-MSH induced B16F10 cells. Furthermore, MITF is found to be a key regulatory transcription factor in melanin synthesis; it was down-regulated by LOE through ERK phosphorylation. In this experiment, PD98059 (MEK inhibitor) was used to check whether LOE directly regulated the activity of ERK. Although LOE exerted inhibitory effect on melanin synthesis, we could not observe this effect in PD98059-treated α-MSH induced B16F10. These results strongly indicate that LOE is related to ERK activation and MITF degradation in anti-skin pigmentation. Hence, LOE should be utilized as a whitening agent of skin in the near future.

• The Korean Journal of Physiology and Pharmacology
• /
• v.17 no.2
• /
• pp.133-137
• /
• 2013

Vascular cell adhesion molecule 1 (VCAM-1), intercellular adhesion molecule 1 (ICAM-1), P- and E-selectin play a pivotal role for initiation of atherosclerosis. Ginsenoside, a class of steroid glycosides, is abundant in Panax ginseng root, which has been used for prevention of illness in Korea. In this study, we investigated the mechanism(s) by which ginsenoside Rg2 may inhibit VCAM-1 and ICAM-1 expressions stimulated with lipopolysaccharide (LPS) in human umbilical vein endothelial cell (HUVEC). LPS increased VCAM-1 and ICAM-1 expression. Ginsenoside Rg2 prevented LPS-mediated increase of VCAM-1 and ICAM-1 expression. On the other hand, JSH, a nuclear factor kappa B (NF-${\kappa}B$) inhibitor, reduced both VCAM-1 and ICAM-1 expression stimulated with LPS. SB202190, inhibitor of p38 mitogen-activated protein kinase (p38 MAPK), and wortmannin, phosphatidylinositol 3-kinase (PI3-kinase) inhibitor, reduced LPS-mediated VCAM-1 but not ICAM-1 expression. PD98059, inhibitor of mitogen-activated protein kinase kinase/extracellular signal-regulated kinase (MEK/ERK) did not affect VCAM-1 and ICAM-1 expression stimulated with LPS. SP600125, inhibitor of c-Jun N-terminal kinase (JNK), reduced LPS-mediated ICAM-1 but not VCAM-1 expression. LPS reduced IkappaB${\alpha}$ ($I{\kappa}B{\alpha}$) expression, in a time-dependent manner within 1 hr. Ginsenoside Rg2 prevented the decrease of $I{\kappa}B{\alpha}$ expression stimulated with LPS. Moreover, ginsenoside Rg2 reduced LPS-mediated THP-1 monocyte adhesion to HUVEC, in a concentration-dependent manner. These data provide a novel mechanism where the ginsenoside Rg2 may provide direct vascular benefits with inhibition of leukocyte adhesion into vascular wall thereby providing protection against vascular inflammatory disease.

• Proceedings of the Korean Society of Dyers and Finishers Conference
• /
• 2012.03a
• /
• pp.50-50
• /
• 2012

투습방수필름으로 많이 사용되고 있는 폴리우레탄(PU)에 광촉매 기능성을 가지고 있는 나노-$TiO_2$(Degussa P25)를 1~10wt% 복합시킨 후, 은(Ag)이온 수용액에서 자외선 조사에 의한 광증착시키는 과정을 거쳐 은이 도핑된 PU/$TiO_2$/Ag 하이브리드 멤브레인 필름을 제조하였다. (주)비에스지에서 제공받은 PU/DMF/MEK 용액에 $TiO_2$를 초음파로 균일하게 분산배합한 후, 필름캐스팅하여 만든 필름을 AgNO3 수용액에 침지시키고 254nm의 자외선을 30~120초 동안 조사하는 광증착법으로 은을 환원시켜 도핑시켰다. 은 도핑된 하이브리드 필름을 Shaking flask method에서 폐렴간균, 황색포도상구균에 대한 항균성을 측정하고, Clear zone method에서 대장균에 대한 항균성을 측정한 결과, $TiO_2$ 함량이 3wt% 이상이고 UV조사시간이 60초 이상인 경우 99.9% 이상의 항균성을 나타내는 것을 확인하였다.

• International Journal of Oral Biology
• /
• v.34 no.2
• /
• pp.115-121
• /
• 2009

Bone morphogenetic protein (BMP) 2 is a potent osteogenic factor. Although both Smad1/5 and mitogenactivated protein kinases (MAPKs) are activated by BMP2, the hierarchical relationship between them is unclear. In this study, we examined if BMP2-stimulated MAPK activation is regulated by Smad1/5 or vice versa. When C2C12 cells were treated with BMP2, the activation of extracellular signal-regulated kinase (ERK), p38 MAPK and c-Jun-N-terminal kinase was evident within 5 min. The knockdown of both Smad1 and Smad5 by small interfering RNA did not affect the activation of these MAPKs. In addition, neither the overexpression of Smad1 nor Smad5 induced ERK activation. When ERK activation was induced by constitutively active MEK1 expression, the protein level and activation of Smad1 increased. Furthermore, the inhibition of constitutively active BMP receptor type IB-induced ERK activation significantly suppressed Smad1 activation. These results indicate that Smad1/5 activation is not necessary for BMP2-induced MAPK activation and also that ERK positively regulates Smad1 activation.

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.7 no.2
• /
• pp.279-288
• /
• 1997

The penetrating speeds of organic solvents into the nude mouse skin were measured by in vitro methods(diffusion cell methods) and in vivo methods(measuring internal residues of the organic solvents). The results were as follows: 1. The penetrating speeds of toluene, m-xylene, MEK, MIBK, ethanol, IPA and 2-bromopropane into the skin were $0.4832mg/cm^2/h$, $0.1738mg/cm^2/h$, $1.124mg/cm^2/h$, $0.6627mg/cm^2/h$, $1.747mg/cm^2/h$, $1.359mg/cm^2/h$, and 2-bromopropane $4.165mg/cm^2/h$ respectively. 2. The penetrating speeds of the mixtures of two, toluene and m-xylene, the mixture of three, IPA, ethyl acetate, and MIBK, the mixture of five, toluene, m-xylene, IPA, ethyl acetate, and MIBK were $0.172mg/cm^2/h$, $1.431mg/cm^2/h$, and $2.983mg/cm^2/h$ respectively. 3. The absorption speeds of 2-bromopropane and styrene which were measured by in vivo processes were $3.12mg/cm^2/h$ and $1.44mg/cm^2/h$ respectively. The absorption speed of 2-bromopropane mesured in vivo was 74.9% of that measured by in vitro methods, $4.165mg/cm^2/h$.