• Journal of Life Science
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• v.25 no.10
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• pp.1103-1109
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• 2015

Cholinergic innervation of the hippocampus is known to be correlated with learning and memory. The cholinergic agonist carbachol (CCh) modulate synaptic plasticity and produced long-term synaptic depression (LTD) in the hippocampus. However, the exact mechanisms by which the cholinergic system modifies synaptic functions in the hippocampus have yet to be determined. This study introduces an acetylcholine receptor-mediated LTD that requires internalization of alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA) receptors on the postsynaptic surface and their intracellular mechanism in the hippocampus. In the present study, we showed that the application of the cholinergic agonist CCh reduced the surface expression of GluA2 on synapses and that this reduction was prevented by the M1 muscarinic acetylcholine receptor antagonist pirenzepine in primary hippocampal neurons. The interaction between GluA2 and the glutamate receptor-interacting protein 1 (GRIP1) was disrupted in a hippocampal slice from a rat upon CCh simulation. Under the same conditions, the binding of GluA2 to adaptin-α, a protein involved in clathrin-mediated endocytosis, was enhanced. The current data suggest that the activation of LTD, mediated by the acetylcholine receptor, requires the internalization of the GluA2 subunits of AMPA receptors and that this may be controlled by the disruption of GRIP1 in the PDZ ligand domain of GluA2. Therefore, we can hypothesize that one mechanism underlying the LTD mediated by the M1 mAChR is the internalization of the GluA2 AMPAR subunits from the plasma membrane in the hippocampal cholinergic system.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.2
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• pp.340-347
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• 1994

The specimens used in this study were obtained from patients with primary gastric carcinoma and adjacent non-malignant mucosa from the same patients. Using the techniques of immunocyto chemicstry and in situ hybridization, transforming growth $factor-{\alpha}(TGF-{\alpha})$ and epiderimal growth factor receptor (EGF-R) nRNAs were identified. $TGF-{\alpha}$ was observed in macrophages and dividing tumor cells but, not in normal cells. EGF-R was observed both in malignant and non-malignant gastric tissues. Although normally, $TGF-{\alpha}$ is not seen in normal gastric tissues, $TGF-{\alpha}$ was discovered in the adjacent non-malignant tissue of histolgically normal, which strongly suggest that $TGF-{\alpha}$ is involved in the differentiation of cancer cells. Immunocytochemicstry using EMB-11 antibody identified the existence of macrophages which express $TGF-{\alpha}$ and EGF-R mRNA. Protein products of EGF-R was identfified using monoclonal antibody. Cancer cells were also identified in the non-malignant normal tissues by the method of immunocytochemicstry using carcino embryonic antigen (CEA)antibody. It is considered that the activity of $TGF-{\alpha}$ increased as tumor cell prolifierates. Immunocytochemistry and in situ hybridization techniques can be used to diagnose gastric cancer along with the use of ${\alpha}-feto$ protein and CEA.

• Toxicological Research
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• v.29 no.1
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• pp.21-25
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• 2013

The selective targeting of an integrin ${\alpha}_v{\beta}_3$ receptor using radioligands may enable the assessment of angiogenesis and integrin ${\alpha}_v{\beta}_3$ receptor status in tumors. The aim of this research was to label a peptidomimetic integrin ${\alpha}_v{\beta}_3$ antagonist (PIA) with $^{99m}Tc(CO)_3$ and to test its receptor targeting properties in nude mice bearing receptor-positive tumors. PIA was reacted with tris-succinimidyl aminotriacetate (TSAT) (20 mM) as a PIA per TSAT. The product, PIA-aminodiacetic acid (ADA), was radiolabeled with $[^{99m}Tc(CO)_3(H_2O)_3]^{+1}$, and purified sequentially on a Sep-Pak C-18 cartridge followed by a Sep-Pak QMA anion exchange cartridge. Using gradient C-18 reverse-phase HPLC, the radiochemical purity of $^{99m}Tc(CO)_3$-ADA-PIA (retention time, 10.5 min) was confirmed to be > 95%. Biodistribution analysis was performed in nude mice (n = 5 per time point) bearing receptor-positive M21 human melanoma xenografts. The mice were administered $^{99m}Tc(CO)_3$-ADA-PIA intravenously. The animals were euthanized at 0.33, 1, and 2 hr after injection for the biodistribution study. A separate group of mice were also co-injected with 200 ${\mu}g$ of PIA and euthanized at 1 hr to quantify tumor uptake. $^{99m}Tc(CO)_3$-ADA-PIA was stable in phosphate buffer for 21 hr, but at 3 and 6 hr, 7.9 and 11.5% of the radioactivity was lost as histidine, respectively. In tumor bearing mice, $^{99m}Tc(CO)_3$-ADA-PIA accumulated rapidly in a receptor-positive tumor with a peak uptake at 20 min, and rapid clearance from blood occurring primarily through the hepatobiliary system. At 20 min, the tumor-to-blood ratio was 1.8. At 1 hr, the tumor uptake was 0.47% injected dose (ID)/g, but decreased to 0.12% ID/g when co-injected with an excess amount of PIA, indicating that accumulation was receptor mediated. These results demonstrate successful $^{99m}TC$ labeling of a peptidomimetic integrin antagonist that accumulated in a tumor via receptor-specific binding. However, tumor uptake was very low because of low blood concentrations that likely resulted from rapid uptake of the agent into the hepatobiliary system. This study suggests that for $^{99m}Tc(CO)_3$-ADA-PIA to be useful as a tumor detection agent, it will be necessary to improve receptor binding affinity and increase the hydrophilicity of the product to minimize rapid hepatobiliary uptake.

• Animal cells and systems
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• v.13 no.2
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• pp.205-212
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• 2009

Known as a female hormone, estrogen, performs important functions, and the activities of the hormone are mediated via the estrogen receptor. The principal objective of the present study was to assess the effects of a estrogen receptor agonist in male reproductive organs. In this study, the estrogen receptor alpha agonist, PPT, was injected subcutaneously into adult male mice. The effects of PPT on the murine reproductive system were histologically assessed at 3,5, and 8 weeks after treatment. In the treatment group, reductions were observed in the weight of the body, testis and epididymis. Microscopic examination revealed a reduction in seminiferous tubular diameter in the testis, and epithelial cell height in the epididymis during the experiment. 8 weeks after treatment, spermatogenesis was not detected, nor was the lumen of the seminiferous tubules. In the fertility test, 1 week after PPT injection, the fertilizing ability of males was decreased, and on the 2nd and 3rd weeks, complete infertility was observed. In conclusion, the injection of high concentrations of PPT into adult males induced physiological changes, including infertility, and also induced morphological changes, including a reduction in the height of epithelial cells within the reproductive system.

• BMB Reports
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• v.42 no.2
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• pp.91-95
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• 2009

Peroxisome proliferator-activated receptor $\alpha$ and estrogen are believed to be involved in metabolic changes leading to obesity. To test this relationship, we divided female wildtype and PPAR$\alpha$-deficient mice fed on a high fat diet into the following groups: mock-operated, ovariectomized (OVX), and $E_2$-treated. The visceral white adipose tissue and plasma cholesterol levels were increased significantly in wild type OVX and decreased in the $E_2$-treated group, but interestingly not in PPAR$\alpha$-deficient mice. The mRNA levels of lipoprotein lipase in adipose tissue were also increased in only wild type OVX and decreased significantly in $E_2$-treated mice. These novel results suggest the possibility of signaling crosstalk between PPAR$\alpha$ and $E_2$, causing obesity in vivo.

• The Korean Journal of Physiology and Pharmacology
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• v.7 no.5
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• pp.279-282
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• 2003

To investigate the effect of fluoxetine, one of selective serotonin reuptake inhibitors (SSRIs), on the immune system, human peripheral blood mononuclear cells (PBMC) were treated with fluoxetine $(10^{-7}\;M)$ for 24 h, and immune-related genes were analyzed by cDNA microarray. Expression of the immunerelated genes such as CD107b (LAMP-2), CD47 receptor (thrombospondin receptor), CD5 antigen-like (scavenger receptor cysteine rich family), copine III (CPNE3), interleukin (IL)-18 (interferon-gammainducing factor), integrin alpha 4 (CD49d), integrin alpha L subunit (CD11a), IL-3 receptor alpha subunit, L apoferritin, and small inducible cytokine subfamily A (Cys-Cys) member 13 (SCYA13) was induced by fluoxetine. This result suggests that fluoxetine may affect the immune system, and provides fundamental data for the involvement of SSRIs on immunoregulation.

• Molecules and Cells
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• v.26 no.3
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• pp.285-290
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• 2008

Estrogen-induced proliferation in estrogen receptor (ER)-positive breast cancer cells is primarily mediated through two distinct intracellular receptors, $ER{\alpha}$ and $ER{\beta}$. Although tumor necrosis factor alpha ($TNF{\alpha}$) and $E2/ER{\alpha}$ are known to exert opposing effects on cell proliferation in MCF-7 cells, the mechanism by which $TNF{\alpha}$ antagonizes $E2/ER{\alpha}$-mediated cell proliferation is not well understood. The present study suggests that reduced cell survival in response to $TNF{\alpha}$ treatment in MCF-7 cells may be associated with the down-regulation of $ER{\alpha}$ protein. The decrease in $ER{\alpha}$ protein level was accompanied by an inhibition of $ER{\alpha}$ gene transcription. Cell viability was decreased synergistically by the combined treatment with $ER{\alpha}$-siRNA and $TNF{\alpha}$. Furthermore, pretreatment of cells with the PI3-kinase (PI3K)/ Akt inhibitor, LY294002, markedly enhanced $TNF{\alpha}$-induced down-regulation of the $ER{\alpha}$ protein, suggesting that the PI3K/Akt pathway might be involved in control of the $ER{\alpha}$ level. Moreover, down-regulation of $ER{\alpha}$ by $TNF{\alpha}$ was not inhibited in cells that were pretreated with the proteasome inhibitors, MG132 and MG152, which suggests that proteasome-dependent proteolysis does not significantly influence $TNF{\alpha}$-induced down-regulation of $ER{\alpha}$ protein. In contrast, the effect of the PI3K/Akt inhibitor on $ER{\alpha}$ was blocked in cells that were treated with LY294002 in the presence of the proteasome inhibitors. Collectively, our findings show that the $TNF{\alpha}$ may partly regulate the growth of MCF-7 breast cancer cells through the down-regulation of $ER{\alpha}$ expression, which is primarily mediated by a PI3K/Akt signaling.

• Biomedical Science Letters
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• v.19 no.3
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• pp.261-265
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• 2013

The corpus luteum is a transient endocrine gland essential for regulation of the ovarian cycle as well as for establishing and maintaining pregnancy. Prostaglandin $F_{2{\alpha}}$ (PGF) initiates functional and structural regression of the corpus luteum and therefore is an important regulator of the estrous cycle. It is a matter of debate whether the endothelial cells of the bovine corpus luteum express PGFR, the cognate receptor for PGF. Therefore, the aim of this study was to assess the expression of PGFR in bovine endothelial cells. Endothelial cells were isolated from the bovine corpus luteum of the mid-luteal stage using magnetic beads and cultured in vitro. We demonstrate that this isolation procedure generates a pure culture of endothelial cells as confirmed by synthesis of Factor VIII and lack of expression of $3{\beta}$-hydroxysteroid dehydrogenase. By RT-PCR, Western blot and immunofluorescence analyses, we further show that the cultured endothelial cells produced PGFR. This model system can be utilized to provide an experimental system to investigate the role of PGF on endothelial cells during the reproductive cycle.

• Molecules and Cells
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• v.26 no.4
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• pp.409-414
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• 2008

The cholesteryl ester transfer protein (CETP), a key player in cholesterol metabolism, has been shown to promote the transfer of triglycerides from very low density lipoprotein (VLDL) and low density lipoprotein (LDL) to high density lipoprotein (HDL) in exchange for cholesterol ester. Here we demonstrate that farnesoid X receptor ${\alpha}$ ($FXR{\alpha}$; NR1H4) down-regulates CETP expression in HepG2 cells. A $FXR{\alpha}$ ligand, chenodeoxycholic acid (CDCA), suppressed basal mRNA levels of the CETP gene in HepG2 cells in a dose-dependent manner. Using gel shift and chromatin immunoprecipitation (ChIP) assays, we found that $FXR{\alpha}$ could bind to the liver X receptor ${\alpha}$ ( $LXR{\alpha}$; NR1H3) binding site (LXRE; DR4RE) located within the CETP 5' promoter region. $FXR{\alpha}$ suppressed $LXR{\alpha}$-induced DR4RE-luciferase activity and this effect was mediated by a binding competition between $FXR{\alpha}$ and $LXR{\alpha}$ for DR4RE. Furthermore, the addition of CDCA together with a $LXR{\alpha}$ ligand, GW3965, to HepG2 cells was shown to substantially decrease mRNA levels of hepatic CETP gene, which is typically induced by GW3965. Together, our data demonstrate that $FXR{\alpha}$ down-regulates CETP gene expression via binding to the DR4RE sequence within the CETP 5' promoter and this $FXR{\alpha}$ binding is essential for $FXR{\alpha}$ inhibition of $LXR{\alpha}$-induced CETP expression.

• Molecules and Cells
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• v.20 no.3
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• pp.378-384
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• 2005

Estrogen metabolites are carcinogenic. The comparative mitogenic activities of $17{\beta}$-estradiol (E2) and four metabolites, 2-hydroxyestradiol (2-OHE2), 4-hydroxyestradiol (4-OHE2), $16{\alpha}$-hydroxyestrone ($16{\alpha}$-OHE1) and 2-methoxyestradiol (2-ME), were determined in estrogen receptor(ER)-positive MCF-7 human breast cancer cells. Each of the E2 metabolites caused proliferation of the MCF-7 cells, but only E2 and $16{\alpha}$-OHE1 induced a greater than 20-fold increases in transcripts of the progesterone receptor (PR) gene, a classical ER-mediated gene. This suggests that the mitogenic action of E2 and $16{\alpha}$-OHE1 could result from their effects on gene expression via the ER. E2 metabolites altered the expression of E2-regulated proteins including heat shock proteins (Hsps). $16{\alpha}$-OHE1 and 2-ME as well as E2 increased levels of Hsp56, Hsp60, $Hsp90{\alpha}$ and Hsp110 transcripts, and the patterns of these inductions resembled that of PR. Hsp56 and Hsp60 protein levels were increased by all the E2 metabolites. Levels of the transcripts of 3 E2-upregulated proteins (XTP3-transactivated protein A, protein disulfide isomerase-associated 4 protein and stathmin 1) and an E2-downregulated protein (aminoacylase 1) were also affected by the E2 metabolites. These results suggest that the altered expression of Hsps (especially Hsp56 and Hsp60) by E2 metabolites such as E2, $16{\alpha}$-OHE1 and 2-ME could be closely linked to their mitogenic action.