Association of Herpesvirus Saimiri Tip with Lipid Raft Is Essential for Downregulation of T-Cell Receptor and CD4 Coreceptor

Cho, Nam-Hyuk,Kingston, Dior,Chang, Heesoon,Kwon, Eun-Kyung,Kim, Jo-Min,Lee, Jung Hee,Chu, Hyuk,Choi, Myung-Sik,Kim, Ik-Sang,Jung, Jae Ung American Society for Microbiology 2006 Journal of virology Vol.80 No.1

<B>ABSTRACT</B><P>Lipid rafts are membrane microdomains that are proposed to function as platforms for both receptor signaling and trafficking. Our previous studies have demonstrated that Tip of herpesvirus saimiri (HVS), which is a T-lymphotropic tumor virus, is constitutively targeted to lipid rafts and interacts with cellular Lck tyrosine kinase and p80 WD repeat-containing endosomal protein. Through the interactions with Lck and p80, HVS Tip modulates diverse T-cell functions, which leads to the downregulation of T-cell receptor (TCR) and CD4 coreceptor surface expression, the inhibition of TCR signal transduction, and the activation of STAT3 transcription factor. In this study, we investigated the functional significance of Tip association with lipid rafts. We found that Tip expression remarkably increased lipid raft fractions in human T cells by enhancing the recruitment of lipid raft-resident proteins. Genetic analysis showed that the carboxyl-terminal transmembrane, but not p80 and Lck interaction, of Tip was required for the lipid raft localization and that lipid raft localization of Tip was necessary for the efficient downregulation of TCR and CD4 surface expression. Correlated with this, treatment with Filipin III, a lipid raft-disrupting agent, effectively reversed the downregulation of CD3 and CD4 surface expression induced by Tip. On the other hand, Tip mutants that were no longer present in lipid rafts were still capable of inhibiting TCR signaling and activating STAT3 transcription factor activity as efficiently as wild-type (wt) Tip. These results indicate that the association of Tip with lipid rafts is essential for the downregulation of TCR and CD4 surface expression but not for the inhibition of TCR signal transduction and the activation of STAT3 transcription factor. These results also suggest that the signaling and targeting activities of HVS Tip rely on functionally and genetically separable mechanisms, which may independently modulate T-cell function for viral persistence or pathogenesis.</P>

Activation of Urease Apoprotein of Helicobacter pylori

Cho, Myung-Je,Lee, Woo-Kon,Song, Jae-Young,An, Young-Sook,Choi, Sang-Haeng,Choi, Yeo-Jeong,Park, Seong-Gyu,Choi, Mi-Young,Baik, Seung-Chul,Lee, Byung-Sang,Rhee, Kwang-Ho The Korea Society for Microbiology 1999 大韓微生物學會誌 Vol.34 No.6

H. pylori produces urease abundantly amounting to 6% of total protein of bacterial mass. Urease genes are composed of a cluster of 9 genes of ureC, ureD, ureA, ureB, ureI, ureE, ureF, ureG, ureH. Production of H. pylori urease in E. coli was studied with genetic cotransformation. Structural genes ureA and ureB produce urease apoprotein in E. coli but the apoprotein has no enzymatic activity. ureC and ureD do not affect urease production nor enzyme activity ureF, ureG, and ureH are essential to produce the catalytically active H. pylori urease of structural genes (ureA and ureB) in E.coli. The kinetics of activation of H. pylori urease apoprotein were examined to understand the production of active H. pylori urease. Activation of H. pylori urease apoprotein, pH dependency, reversibility of $CO_2$ binding, irreversibility of $CO_2$ and $Ni^{2+}$ incorporation, and $CO_2$ dependency of initial rate of urease activity have been observed in vitro. The intrinsic reactivity (ko) for carbamylation of urease apoprotein co expressed with accessory genes was 17-fold greater than that of urease apoprotein expressed without accessory genes. It is concluded that accessory genes function in maximizing the carbamylating deprotonated ${\varepsilon}$-amino group of Lys 219 of urease B subunit and metallocenter of urease apoprotein is supposed to be assembled by reaction of a deprotonated protein side chain with an activating $CO_2$ molecule to generate ligands that facilitate productive nickel binding.

Steroid Hormone Receptor/Reporter Gene Transcription Assay for Food Additives and Contaminants

Sang-Hee Jeong,Joon-Hyoung Cho,Jong-Myung Park 한국독성학회 2006 Toxicological Research Vol.22 No.1

Many of endocrine disrupting chemicals induce effects via interaction with hormone receptors and responsive elements in target cells. We investigated endocrine disrupting effects of some food additives and contaminants including BHA, BHT, ethoxyquin, propionic acid, sorbic acid, benzoic acid, CPM, aflatoxin B1, cadmium chloride, genistein, TCDD and PCBs in yeast transformants expressing human steroid hormone receptors along with steroid responsive elements. The response limit of genetically recombinant yeast to 17β-estradiol, testosterone and progesterone was 1 × 10<SUP>-16</SUP>, 1 × 10<SUP>-12</SUP> and 1 × 10<SUP>-13</SUP> M, respectively. BHT induced weak transcriptional activity in estrogen sensitive yeast, while BHA and sorbic acid interacted weakly with androgen receptor/responsive element. CPM induced transcriptional activities in all types of yeasts sensitive to steroid hormones. Zearalenone and genistein induced high transcriptional activation in estrogen sensitive yeast with relative potencies almost 108 folds lower than 17β-estradiol. TCDD induced transcriptional activation weakly in estrogen- and progesterone- sensitive yeasts. This study elucidated that recombinant yeast is a sensitive and high-throughput system and can be used for the direct assessment on chemical interactions with steroid receptors and responsive elements. Also, the present study raises the requirement of evaluation on the endocrine disrupting effects of BHT, BHA, sorbic acid, CPM and TCDD for their transcription activity in yeast screening system though weak in intensity

Trabecular thickness measurement in cancellous bones: postmortem rat studies with the zoom-in micro-tomography technique

Cho, Myung Hye,Chun, In Kon,Lee, Sang Chul,Cho, Min Hyoung,Lee, Soo Yeol IOP Pub 2005 PHYSIOLOGICAL MEASUREMENT Vol.26 No.5

<P>Using the cross-sectional images taken with the zoom-in micro-tomography technique, we measured trabecular thicknesses of femur bones in postmortem rats. Since the zoom-in micro-tomography technique is capable of high resolution imaging of a small local region inside a large subject, we were able to measure the trabecular thickness without extracting bone samples from the rats. For the zoom-in micro-tomography, we used a micro-tomography system consisting of a micro-focus x-ray source, a 1248 ? 1248 flat-panel x-ray detector and a precision scan mechanism. To compensate for the limited spatial resolution in the zoom-in micro-tomography images, we used the fuzzy distance transform for the calculation of the trabecular thickness. To validate the trabecular thickness measurement with the zoom-in micro-tomography images, we compared the measurement results with those obtained from the conventional micro-tomography images of the extracted bone samples. The difference between the two types of measurement results was less than 2.5%.</P>

Evaluation of Red Pigment of Cockscomb Flower in Model Food Systems as a Natural Food Colorant

Sang Yeol Lee(이상열),Yong Chul Shin(신용철),Si Myung Byun(변시명),Jae-Sun Jo(조재선),Sook Ja Cho(조숙자) 한국식품과학회 1986 한국식품과학회지 Vol.18 No.5

Partial characterization of phosphotriesterase activity from the earthworm, Eisenia andrei

( Myung Sik Lee ),( Sung Jin Cho ),( Jong Ae Lee ),( Soon Cheol Park ) 한국토양동물학회 2002 춘계학술대회논문집 Vol.2002 No.-

Phosphotriesterase (PTE) receives attention because it seems to be associated with the detoxication of organophosphorous pesticides and organophosphate resistance mechanism. In order to understand the biodegradation of phosphotriester pesticides and its signicance in the earthworm, a major non-target animal of pesticides, selected properties of phosphotiriesterase activity derived form the crude extract of Eisenia andrei were investigated. Pte activity appeared to be primarily localized in intestinal tissues. The highest level of PTE activity was found in epithelial tissue. THE NATIVE MOLECULAR WEIGHT OF EARTHWORM pte WAS 260 kDa and the isoelectric point was approximately 4. The optimal PH was approximately 9. The earthworm PTE had a substrate anity fof paraoxon with im value in the millimolar range. The presence of EGTA and EDTA completely abolished the activity and replacement of ca2+ ion is esential to maintain the activity.

An Efficient Direct Synthesis of β-Ferrocenylketones Catalyzed by Ruthenium

Cho, Chan-Sik,Park, Ji-Hyuk,Kim, Bok-Tae,Kim, Tae-Jeong,Shim, Sang-Chul,Kim, Myung-Chul Korean Chemical Society 2004 Bulletin of the Korean Chemical Society Vol.25 No.3

Phylogenetic Relationships of Soranthera ulvoidea (Chordariaceae, Phaeophyceae) on the Basis of Morphology and Molecular Data

Cho, Ga-Youn,Kim, Myung-Sook,Boo, Sung-Min The Korean Society of Phycology 2005 ALGAE Vol.20 No.2

The brown algal family Chordariaceae sensu lato is a focus of taxonomy because recent studies suggest a broad concept of the family, including genera formerly classified in the Dictyosiphonales. Using morphology, plastid rbcL and nrDNA ITS sequences, we evaluated relationships of the monotyic genus Soranthera (S. ulvoidea), which has been classified in the Punctariaceae. The species occurs in Bering Sea and Aleutian Islands, Alaska to Baja California. Thalli are globose to lobed, hollow, 3-5 cm in diameter, and covered with evenly distributed sori. However, two forms within the species are recognized: f. ulvoidea for globose forms and f. difformis for lobed forms. Plastid rbcL and nuclear ITS region sequences were newly determined in samples of S. ulvoidea from the Pacific coast of the North America. We found little variations in the ITS sequences among samples of S. ulvoidea from five different locations and in the rbcL region from two different locations. These results do not support previous classification of f. ulvoidea and f. difformis within the species. All analyses of our rbcL sequence dataset show that Soranthera was placed in the Chordariaceae s.l., but more related to Botrytella than Punctaria and Asperococcus.

Protein Carboxylmethylation in Porcine Spleen is Mainly Mediated by Class I Protein Carboxyl O-Methyltransferase

Cho, Jae-Youl,Kim, Sung-Soo,Kwon, Myung-Hee,Kim, Seong-Hwan,Lee, Hyang-Woo,Hong, Sung-Youl The Pharmaceutical Society of Korea 2004 Archives of Pharmacal Research Vol.27 No.2

The functional role of protein carboxylmethylation (PCM) has not yet been clearly elucidated in the tissue level. The biochemical feature of PCM in porcine spleen was therefore studied by investigating the methyl accepting capacity (MAC) of natural endogenous substrate proteins for protein carboxyl O-methyltransferase (PCMT) in various conditions. Strong acidic and alkaline-conditioned (at pH 11.0) analyses of the MAC indicated that approximately 65% of total protein methylation seemed to be mediated by spleen PCMT. The hydrolytic kinetics of the PCM products, such as carboxylmethylesters (CMEs), under mild alkaline conditions revealed that there may be three different kinds of CMEs [displaying half-times (T$_{1}$2/) of 1.1 min (82.7% of total CMEs), 13.9 min (4.6%), and 478.0 min (12.7%)], assuming that the majority of CME is base-labile and may be catalyzed by class I PCMT. In agreement with these results, several natural endogenous substrate proteins (14, 31 and 86 kDa) were identified strikingly by acidic-conditioned electrophoresis, and their MAC was lost upon alkaline conditions. On the other hand, other proteins (23 and 62 kDa) weakly appeared under alkaline conditions, indicating that PCM mediated by class II or III PCMT may be a minor reaction. The MAC of an isolated endogenous substrate protein (23-kDa) was also detected upon acidic-conditioned electrophoresis. Therefore, our date suggest that most spleen PCM may be catalyzed by class I PCMT, which participates in repairing aged proteins.

In Vivo Effects of CETP Inhibitory Peptides in Hypercholesterolemic Rabbit and Cholesteryl Ester Transfer Protein-Transgenic Mice

Cho, Kyung-Hyun,Shin, Yong-Won,Choi, Myung-Sook,Bok, Song-Hae,Jang, Sang-Hee,Park, Yong-Bok Korean Society for Biochemistry and Molecular Biol 2002 Journal of biochemistry and molecular biology Vol.35 No.2

We previously reported that cholesteryl ester transfer protein (CETP) inhibitory peptides (designated $P_{28}$ and $P_{10})$ have anti-atherogenic effects in hypercholesterolemic rabbits (Biochim. Biophys. Acta (1998) 1391, 133-144). To further investigate those effects, we studied rabbit plasma that was collected after 30 h of a $P_{28}$ or $P_{10}$ injection. We found that there is a strong correlation between the in vivo CETP inhibition effects and alterations of lipoprotein particle size distribution in rabbit plasma, as determined on an agarose gel electrophoresis and gel filtration column chromatography. In vivo effects of the peptide were observed again in C57BL/6 mice that expressed simian CETP. The $P_{28}$ or $P_{10}$ peptide ($7\;{\mu}g/g$ of body weight) that was dissolved in saline was injected subcutaneously into the mice. The $P_{28}$ injection caused the partial inhibition of plasma CETP activity up to 50%, decreasing the total plasma cholesterol concentration by 30%, and increasing the ratio of HD/total-cholesterol concentration by 150% in the CETP-transgenic (tg) mice. The CETP inhibition by the $P_{28}$ or $P_{10}$ made alterations that modulated the size re-distribution of the lipoproteins in the blood stream. Particle size of the very low (VLDL) and low density lipoproteins (LDL) from the peptide-injected group was highly decreased compared to the saline-injected group (determined on the gel filtration column chromatography). In contrast, The HDL particle size of the $P_{28}$-injected group increased compared to the control group (saline-injected). The expression level of the CETP mRNA of the $P_{28}$-injected CETP-tg mouse appeared lower than the saline-injected CETP-tg mouse. These results suggest that the injection of the CETP inhibitory peptide could affect the CETP expression level in the liver by influencing lipoprotein metabolism.