Byung Oh Kim

Direct Participation of Sam68, the 68-Kilodalton Src-Associated Protein in Mitosis, in the CRM1-Mediated Rev Nuclear Export Pathway

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) replication requires efficient nuclear export of incompletely spliced and unspliced HIV-1 mRNA transcripts, which is achieved by Rev expression at an early stage of the viral life cycle. We have recently shown that expression of Sam68, the 68-kDa Src-associated protein in mitosis, is able to alleviate Rev function block in astrocytes by promoting Rev nuclear export. In the present study, we utilized an antisense RNA expression strategy to down-modulate constitutive Sam68 expression and examined its effect on Rev function, HIV-1 gene expression, and viral replication. These results showed that down-modulation of constitutive Sam68 expression markedly inhibited HIV-1 production in 293T cells and viral replication in T lymphocytes such as Jurkat and CEM cells, as well as human peripheral blood mononuclear cells (PBMCs). Rev-dependent in trans complementation and reporter gene assays further demonstrated that inhibition of HIV-1 gene expression by Sam68 down-modulation was due to impeded Rev activity. Moreover, digital fluorescence microscopic imaging revealed that down-modulation of Sam68 expression caused exclusive nuclear retention and colocalization of both Rev and CRM1. Taken together, these data suggest that adequate Sam68 expression is required for Rev function and, thereby, for HIV-1 gene expression and viral replication, and they support the notion that Sam68 is directly involved in the CRM1-mediated Rev nuclear export pathway.

Atopic dermatitis‐mitigating effects of new Lactobacillus strain, Lactobacillus sakei probio 65 isolated from Kimchi

Atopic dermatitis (AD) is an inflammatory skin disease. Probiotics have been reported to modulate immune responses and thus are now being suggested as potential treatments for allergies. In this study, we investigated the inhibitory effects of Lactobacillus sakei probio 65 isolated from Kimchi on artificially inducing AD in NC/Nga mice.

Activation of Egr-1 Expression in Astrocytes by HIV-1 Tat: New Insights into Astrocyte-Mediated Tat Neurotoxicity

Human immunodeficiency virus type 1 (HIV-1) Tat plays an important role in HIV-associated neuropathogenesis; the underlying mechanisms are still evolving. We have recently shown that HIV-1 Tat induces expression of glial fibrillary acidic protein (GFAP), a characteristic of HIV-1 infection of the central nervous system. We have also shown that the Tat-induced GFAP expression in astrocytes is regulated by p300 and that deletion of the early growth response 1 (Egr-1) cis-transacting element within the p300 promoter abolishes Tat-induced GFAP expression. In this study, we further examined the relationship between Tat and Egr-1 in astrocytes. We found increased Egr-1 protein expression in Tat-expressing human astrocytoma cells and mouse primary astrocytes. Using the Egr-1 promoter-driven firefly luciferase reporter gene assay and the site-directed mutagenesis, we demonstrated that Tat increased Egr-1 expression by transactivating the Egr-1 promoter and involving specific serum response elements within the promoter. Consistent with these data, we showed that Tat transactivation of the Egr-1 promoter was abrogated when astrocytes were cultured in serum-reduced media. Taken together, these results reveal that Tat directly transactivates Egr-1 expression and suggest that Tat interaction with Egr-1 is probably one of the very upstream molecular events that initiate Tat-induced astrocyte dysfunction and subsequent Tat neurotoxicity.

Induction of C Chemokine XCL1 (Lymphotactin/Single C Motif-1α/Activation-Induced, T Cell-Derived and Chemokine-Related Cytokine) Expression by HIV-1 Tat Protein

HIV-1 Tat has been proposed as a key agent in many AIDS-related disorders, including HIV-1-associated neurological diseases. We have recently shown that Tat expression induces a significant increase in T lymphocytes in the brains of Tat transgenic mice. The CNS infiltration of T lymphocytes has been noted in AIDS patients. In the present study using this unique genetic system we attempted to understand the underlying mechanisms of Tat expression-induced infiltration of T lymphocytes by examining chemokine expression. RNase protection assay revealed that in addition to CCL2 (monocyte chemoattractant protein-1), CCL3 (macrophage inflammatory protein-1α (MIP-1α)), CCL4 (MIP-1β), CCL5 (RANTES), CXCL2 (MIP-2), and CXCL10 (inducing protein-10), XCL1 (lymphotactin/single C motif-1α/activation-induced, T cell-derived and chemokine-related cytokine) was identified to be up-regulated by Tat expression. XCL1 is a C chemokine and plays a specific and important role in tissue-specific recruitment of T lymphocytes. Thus, we further determined the relationship between Tat and XCL1 expression. Tat-induced XCL1 expression was further confirmed by XCL1-specific RT-PCR and ELISA. Combined in situ hybridization and immunohistochemical staining identified astrocytes, monocytes, and macrophages/microglia as XCL1-producing cells in vivo. Using human astrocytes, U87.MG cells, as an in vitro model, activation of XCL1 expression was positively correlated with Tat expression. Moreover, the XCL1 promoter-driven reporter gene assay showed that Tat-induced XCL1 expression occurred at the transcriptional level. Taken together, these results demonstrate that Tat directly trans-activated XCL1 expression and suggest potential roles of Tat-induced XCL1 expression in the CNS infiltration of T lymphocytes during HIV-1 infection and subsequent HIV-1-induced neurological diseases.

Doxycycline-inducible and astrocyte-specific HIV-1 Tat transgenic mice (iTat) as an HIV/neuroAIDS model

HIV-1 Tat is known to be neurotoxic and important for HIV/neuroAIDS pathogenesis. However, the overwhelming majority of the studies involved use of recombinant Tat protein. To understand the contributions of Tat protein to HIV/neuroAIDS and the underlying molecular mechanisms of HIV-1 Tat neurotoxicity in the context of a whole organism and independently of HIV-1 infection, a doxycycline-inducible astrocyte-specific HIV-1 Tat transgenic mouse (iTat) was created. Tat expression in the brains of iTat mice was determined to be in the range of 1–5xa0ng/ml and led to astrocytosis, loss of neuronal dendrites, and neuroinflammation. iTat mice have allowed us to define the direct effects of Tat on astrocytes and the molecular mechanisms of Tat-induced GFAP expression/astrocytosis, astrocyte-mediated Tat neurotoxicity, Tat-impaired neurogenesis, Tat-induced loss of neuronal integrity, and exosome-associated Tat release and uptake. In this review, we will provide an overview about the creation and characterization of this model and its utilities for our understanding of Tat neurotoxicity and the underlying molecular mechanisms.

Different apoptotic effects of saxifragifolin C in human breast cancer cells

Breast cancer is currently the most common form of cancer affecting women. Recent studies have reported that triterpenoid saponins isolated from Androsace umbellata exhibit anti-proliferative effects in several types of cancer cells. However, the cytotoxic effect of saxifragifolin C (Saxi C) on breast cancer cells remains unclear. The purpose of this study is to evaluate the in vitro anti-tumor activity of Saxi C in human breast cancer cells. Our data indicated that MDA-MB-231 cells were more sensitive than MCF-7 cells to Saxi C treatment. In addition, Saxi C inhibited cell survival through the induction of reactive oxygen species and the caspase-dependent pathway in the MDA-MB-231 cells, whereas MCF-7 cells treated with Saxi C underwent the apoptotic cell death in a caspase-independent manner. Although Saxi C treatment resulted in the induction of activation of MAPKs in both types of human breast cancer cells, p38 MAPK and JNK, but not ERK1/2, appeared to be involved in Saxi C-induced apoptosis. Moreover, ERα-overexpressing MDA-MB-231 cells remained alive, whereas the survival of shERα-transfected MCF-7 cells decreased. Taken together, Saxi C induced apoptosis in MCF-7 cells and MDA-MB-231 cells via different regulatory mechanisms, and ERα status might be essential for regulating Saxi C-induced apoptosis in breast cancer cells. Thus, Saxi C is a potential chemotherapeutic agent in breast cancer.

Allicin induces beige-like adipocytes via KLF15 signal cascade

Under specific conditions, white adipose tissue (WAT) depots are readily converted to a brown-like state, which is associated with weight loss. However, whether diet-derived factors directly induce browning of white adipocytes has yet to be established. Thus, we investigated the effects of allicin, one of the major components of garlic, on brown-like adipocyte formation in inguinal WAT (iWAT), and prevention of obesity and related complications in animal models. Allicin significantly increased mRNA and/or protein expression of brown adipocyte markers including uncoupling protein 1 (UCP1) in differentiated mouse embryonic fibroblast cell line 3T3-L1 and differentiated iWAT stromal vascular cells (SVC), suggesting that allicin induced brown-like adipocyte formation in vitro. Concomitantly, allicin markedly enhanced the protein expression of KLF-15 and its interaction with UCP-1 promoter region. Such changes were absent in cells lacking KLF-15, suggesting the critical role of KLF15 in allicin action. Allicin also induced brown-like adipogenesis in vivo along with the appearance of multilocular adipocytes, increased UCP1 expression and increased lipid oxidation. In summary, our data suggest that allicin potentially prevents obesity and associated metabolic disorders such as type 2 diabetes mellitus by enhancing the expression of brown adipocyte-specific genes, including UCP-1, through KLF15 signal cascade.

Comparison of antioxidants potential, metabolites, and nutritional profiles of Korean fermented soybean (Cheonggukjang) with Bacillus subtilis KCTC 13241

AbstractnThis study was carried out to determine the effect of different concentrations of Bacillus subtilis (0, 1, 3, 5, and 7%) on the antioxidant potential and biochemical constituents of traditional Korean fermented soybean, Cheonggukjang (CKJ). The antioxidant capacity was studied using the reducing power, 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) assays and the total phenolic contents (TPC) were measured using the Folin–Ciocalteu method. CKJ prepared using 1% B. subtilis revealed the highest TPC (5.99xa0mg/g), total amino acids (7.43xa0mg/g), DPPH (94.24%), and ABTS (86.03%) radical-scavenging activity and had the highest value of palmitic acid (11.65%), stearic acid (2.87%), and linolenic acid (11.76%). Results showed that the calcium, iron, sodium, and zinc contents increased in the CKJ prepared using 7% B. subtilis from 1481.38 to 1667.32, 41.38 to 317.00, 48.01 to 310.07, and 32.82 to 37.18xa0mg/kg respectively. In conclusion, the present results indicate that the fermentation of soybean with B. subtilis (KCTC 13241) significantly augments the nutritional and antioxidant potential of CKJ and it can be recommended as a health-promoting food source.

Sinigrin attenuates the progression of atherosclerosis in ApoE−/− mice fed a high-cholesterol diet potentially by inhibiting VCAM-1 expression

Atherosclerosis is a complex inflammatory disease associated with elevated levels of atherogenic molecules for leukocyte recruitment. Sinigrin (2-propenylglucosinolate) is found mainly in broccoli, brussels sprouts, and black mustard seeds. Recently, sinigrin has received attention for its role in disease prevention and health promotion. In this study, we examined the effect of sinigrin on development of atherosclerosis in ApoE-/- mice and the expression of adhesion molecules in vascular smooth muscle cells (VSMCs). The serum concentrations of lactate dehydrogenase (LDH), triglyceride (TG), total cholesterol (TC), low density lipoprotein (LDL), calcium (Ca2+), and pro-inflammatory cytokines were reduced by sinigrin treatment in ApoE-/- mice. In addition, oral administration of sinigrin attenuated the mRNA expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), C-C motif chemokine ligand 2 (CCL2), and CCL5 on aorta tissues and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR), liver X receptor (LXR), sterol regulatory element-binding protein-2 (SREBP-2), and low density lipoprotein receptor (LDLR) on liver tissues in ApoE-/- mice. To provide a potential mechanism underlying the action of sinigrin, we evaluated the inxa0vitro effect of sinigrin on the expression of the VCAM-1 in TNF-α-induced VSMCs. The increased expression of VCAM-1 by TNF-α stimulation was significantly suppressed by the treatment of sinigrin (1-100xa0μg/ml) and sinigrin inhibited the nuclear translocation of NF-κB and the phosphorylation of p38 MAPK and JNK pathways, suggesting that sinigrin decreases the TNF-α-stimulated VCAM-1 expression through the suppression of NF-κB and MAP kinases signaling pathways. Overall, sinigrin has the potential to be used in reducing the risks of atherosclerosis.

Absence of AVP1 transcripts in wild type watermelon scions grafted onto transgenic bottle gourd rootstocks

Abstract In this study we confirmed the stable integration of Arabidopsis AVP1 in the genomes of bottle gourd T 3 homozygous lines and its transcription, and additionally evaluated possibility of translocation of the AVP1 mRNA from transgenic bottle gourd rootstocks to wild type watermelon scions. Each AVP1 gene in two bottle gourd T3 lines is abundantly expressed under a field condition. Given the grafting between wild type watermelon scions and AVP1- expressing bottle gourd rootstocks, no translocation of the AVP1 mRNA was detected in leaves, both sexual flowers, and fruits of the scions. Keywords Bottle ground, Gene modified, Graft, RT-PCR, Watermelon Introduction Grafting is now a popular technique for the cultivation of the horticultural crops including cucurbitaceae fruit vegetables, which has been developed not only to control growth and development of the scion but also to enhance tolerance against soil-borne diseases and/or abiotic stresses, such as salinity, low temperature and drought (Jang et al. 2012; Kubota et al. 2008; Lee 1994). In some special regions, where land utility is extremely limited, the allied crops are repeatedly cultivated all the year round (Kubota et al. 2008; Lee 1994), which increases specific pathogens and salinity of the rhizosphere. To overcome the disadvantages of the intensive cultivation, improvement of rootstocks by using genetic engineering is being attempted as a solution (Han et al. 2009; Smolka et al. 2010; Wang et al. 2012). Control of abiotic stresses is an important element to increase total yields in modern agriculture. Plants respond to various abiotic stresses by altering their turgor pressure in vacuoles in order to accomplish selective permeation of solutes through proton pumps (Gaxiola et al. 2001; McNeil et al. 1999). A vacuolar H