Ahnak functions as a tumor suppressor via modulation of TGFβ/Smad signaling pathway

Lee, I H,Sohn, M,Lim, H J,Yoon, S,Oh, H,Shin, S,Shin, J H,Oh, S-H,Kim, J,Lee, D K,Noh, D Y,Bae, D S,Seong, J K,Bae, Y S Macmillan Publishers Limited 2014 Oncogene Vol.33 No.38

We provide detailed mechanisms of Ahnak-mediated potentiation of transforming growth factor β (TGFβ) signaling, which leads to a negative regulation of cell growth. We show that Smad3 interacts with Ahnak through MH2 domain and that Ahnak stimulates Smad3 localization into nucleus leading to potentiating TGFβ-induced transcriptional activity of R-Smad. Moreover, overexpression of Ahnak resulted in growth retardation and cell cycle arrest through downregulation of c-Myc and cyclin D1/D2. We describe results from analyses of Ahnak<SUP>−/−</SUP> mouse model expressing middle T antigen in a mammary gland-specific manner (MMTV<SUP>Tg/+</SUP>Ahnak<SUP>−/−</SUP>), which showed significantly progressed hyperplasia of mammary glands compared with MMTV<SUP>Tg/+</SUP>Ahnak<SUP>+/+</SUP>. Finally, we screened multiple human breast cancer tissues and showed that the expression of Ahnak in cancer tissues is lower than that in control tissues by 50%. Taken together, these data indicate that Ahnak mediates a negative regulation of cell growth and acts as novel tumor suppressor through potentiation of TGFβ signaling.

Bacillus alkalitelluris sp. nov., an alkaliphilic bacterium isolated from sandy soil

Lee, J.-C.,Lee, G. S.,Park, D.-J.,Kim, C.-J. Microbiology Society 2008 International journal of systematic and evolutiona Vol.58 No.11

<P>A Gram-positive, alkaliphilic bacterium, designated strain BA288(T), was isolated from sandy soil. Cells were facultatively anaerobic, endospore-forming rods that were motile by means of peritrichous flagella. The strain grew at 15-40 degrees C and pH 7.0-11.0 (optimally at 30 degrees C and pH 9.0-9.5) and at salinities of 0-4 % (w/v) NaCl. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain BA288(T) belonged to the genus Bacillus and that Bacillus herbersteinensis D-1,5a(T), Bacillus humi LMG 22167(T), Bacillus cohnii DSM 6307(T) and Bacillus litoralis SW-211(T) were the closest neighbours (96.2, 96.0, 96.0 and 95.9 % sequence similarity, respectively). The genomic DNA G+C content was 37.9 mol% and the predominant menaquinone was MK-7. The major cellular fatty acids were anteiso-C(15 : 0), iso-C(15 : 0), C(16 : 0) and iso-C(14 : 0). The peptidoglycan type was A1gamma (meso-diaminopimelic acid). Therefore, on the basis of phylogenetic, phenotypic and chemotaxonomic properties, strain BA288(T) represents a novel species of the genus Bacillus, for which the name Bacillus alkalitelluris sp. nov. is proposed. The type strain is BA288(T) (=KCTC 3947(T) =DSM 16976(T)).</P>

miR-302b maintains ''stemness'' of human embryonal carcinoma cells by post-transcriptional regulation of Cyclin D2 expression

Lee, N.S.,Kim, J.S.,Cho, W.J.,Lee, M.R.,Steiner, R.,Gompers, A.,Ling, D.,Zhang, J.,Strom, P.,Behlke, M.,Moon, S.H.,Salvaterra, P.M.,Jove, R.,Kim, K.S. Academic Press 2008 Biochemical and biophysical research communication Vol.377 No.2

Embryonic stem cells (ESCs) and embryonal carcinoma cells (ECCs) possess the remarkable property of self-renewal and differentiation potency. They are model preparations for investigating the underlying mechanisms of ''stemness''. microRNAs are recently discovered small noncoding RNAs with a broad spectrum of functions, especially in control of development. Here, we show that miR-302b indirectly regulates expression of the pluripotent stem cell marker Oct4, and it directly regulates expression of Cyclin D2 protein, a developmental regulator during gastrulation. Using loss-of function and gain-of function approaches, we demonstrate that functional miR-302b is necessary to maintain stem cell self-renewal and inhibit neuronal differentiation of human ECCs. During retinoic acid-induced neuronal differentiation, Cyclin D2 protein but not mRNA expression is strongly increased, concurrent with the down-regulation of miR-302b and Oct4. Our results suggest that miR-302b plays an important role in maintaining the pluripotency of ECCs and probably ESCs, by post-transcriptional regulation of Cyclin D2 expression.

Thermodynamic behaviors of excitonic emission in ZnO nanorods grown by pulsed laser deposition

Lee, Y.,Lee, D.J.,Cho, H.D.,Yoon, I.T.,Shon, Y.,Lee, S. North-Holland 2017 Journal of luminescence Vol.190 No.-

We investigated the thermodynamic behaviors of the exciton emission in ZnO nanorods that had been grown by laser ablation. The ZnO nanorods exhibited a clear luminescence peak from the neutral donor-bound exciton (D<SUP>0</SUP>X), which persisted near room temperature. Through analyzing temperature-dependences of photoluminescence properties, we found out insignificant thermal-quenching of D<SUP>0</SUP>X, arising from the large donor binding energy (i.e., E<SUB>bD(NR)</SUB> ~ 51.1 +/- 7.3meV). A small discrepancy of E<SUB>bD(NR)</SUB> from ZnO bulks' values (i.e., E<SUB>bD(Bulk)</SUB> = 53 - 72meV) is associated with inhomogeneous thermal-broadening factors such as defect-scattering at the surface of the nanorod. Despite of inhomogeneous thermal-broadening, the ZnO nanorods still have a high luminescence efficiency because of the weak homogeneous thermal-broadening effect (i.e., low exciton-phonon coupling).

Designing the substrate specificity of d-hydantoinase using a rational approach

Lee, S.C.,Chang, Y.,Shin, D.M.,Han, J.,Seo, M.H.,Fazelinia, H.,Maranas, C.D.,Kim, H.S. IPC Science and Technology Press ; Elsevier Scienc 2009 Enzyme and microbial technology Vol.44 No.3

Enzymes that exhibit superior catalytic activity, stability and substrate specificity are highly desirable for industrial applications. These goals prompted the designed substrate specificity of Bacillus stearothermophilusd-hydantoinase toward the target substrate hydroxyphenylhydantoin (HPH). Positions crucial to substrate specificity were selected using structural and mechanistic information on the structural loops at the active site. The size and hydrophobicity of the involved amino acids were rationally changed, and the substrate specificities of the designed d-Hyd mutants were investigated. As a result, M63I/F159S exhibited about 200-fold higher specificity for HPH than the wild-type enzyme. Systematic mutational analysis and computational modeling also supported the rationale used in the design.

Role of n-type seed-layers in microstructural evolution of intrinsic nanocrystalline silicon and solar cell performance

Lee, J.E.,Ahn, S.,Park, J.H.,Yoo, J.,Yoon, K.H.,Kim, D.,Cho, J.S. Elsevier 2013 CURRENT APPLIED PHYSICS Vol.13 No.7

Nanocrystalline silicon (nc-Si:H) thin-film n-i-p solar cells were constructed on flexible stainless steel substrates by plasma-enhanced chemical vapor deposition. Influence of the n-type seed-layer on the microstructural evolution of the subsequent intrinsic nc-Si:H absorbers and the resultant performance of nc-Si:H solar cells was investigated. The crystalline volume fraction of the seed-layer can be effectively controlled by varying the hydrogen (H<SUB>2</SUB>) to silane (SiH<SUB>4</SUB>) gas flow ratio. Defect-dense amorphous regions were observed at the initial growth stage of the i-layers deposited on low crystalline volume fraction (X<SUB>c</SUB><SUP>n</SUP>) n-type seed-layers. Increasing the X<SUB>c</SUB><SUP>n</SUP> reduced the amorphous region at the n/i interface of the i nc-Si:H layers, evidenced by Raman scattering and transmission electron microscopy (TEM) measurements. Elimination of the defect-rich amorphous region within the i-layer by depositing the nc-Si:H solar cells on highly crystalline seed-layer caused significant improvements in the short circuit current density (J<SUB>sc</SUB>) and fill factor (FF). This is mainly due to the enhancement of long-wavelength light response and extraction efficiency of photo-carrier charges. The nc-Si:H solar cells prepared on a highly crystalline seed-layer (X<SUB>c</SUB><SUP>n</SUP>=73%) exhibited a 65.6% higher conversion efficiency than those on the n-type amorphous layers (X<SUB>c</SUB><SUP>n</SUP>=0%).

Probiotic properties of Pediococcus strains isolated from jeotgals, salted and fermented Korean sea-food

Lee, K.W.,Park, J.Y.,Sa, H.D.,Jeong, J.H.,Jin, D.E.,Heo, H.J.,Kim, J.H. Academic Press 2014 Anaerobe Vol.28 No.-

Three Pediococcus pentosaceus strains were isolated from jeotgals, salted and fermented Korean sea-foods, and their probiotic potentials were examined. After 2 h exposure to pH 3.0, P. pentosaceus F66 survived with the survival ratio of 32.6% followed by P. pentosaceus D56 (17.2%) and P. pentosaceus A24 (7.5%). P. pentosaceus F66 also survived better (26.6%) than P. pentosaceus A24 (13.7%) and P. pentosaceus D56 (5.8%) after 2 h exposure to 0.3% bile salts. Three strains grew slowly on MRS broth with 15% NaCl (w/v), reaching the OD<SUB>600</SUB> values of 0.4-0.8 in 36 h. They adhered to Caco-2 cells (10.9-13.9 CFU/cell) with similar degree of adherence of a positive control, Lactobacillus rhamnosus GG (12.8 +/- 0.5 CFU/cell). Three strains possess some desirable enzyme activities such as β-galactosidase, α-glucosidase, β-glucosidase, and N-acetyl-β-glucosidase. From these results, P. pentosaceus F66 seems qualified as a probiotic and can be utilized for fermented foods including jeotgals.

<i>Bacillus</i>‐derived poly‐γ‐glutamic acid attenuates allergic airway inflammation through a Toll‐like receptor‐4‐dependent pathway in a murine model of asthma

Lee, K.,Kim, S.‐,H.,Yoon, H. J.,Paik, D. J.,Kim, J. M.,Youn, J. Blackwell Publishing Ltd 2011 Clinical and experimental allergy Vol.41 No.8

<P><B>Summary</B></P><P><B>Background </B> Asthma is an inflammatory disease of the airways that is mediated by Th2 responses. Poly‐γ‐glutamic acid (γ‐PGA) is an extracellular polymeric compound that is synthesized by <I>Bacillus</I> cells. Previously, we found that γ‐PGA promoted Th1 cell development in a manner dependent on antigen‐presenting cells, but inhibited Th2 cell development.</P><P><B>Objective </B> To investigate the effect of γ‐PGA on dendritic cells (DCs), and its potential for treating Th2‐mediated allergic asthma.</P><P><B>Methods </B> Wild‐type, Toll‐like receptor (TLR)‐2 deficient, and TLR‐4‐defective mice were used. DCs derived from the bone marrow and extracted from the lung were stimulated with γ‐PGA and assayed for the expression of signalling molecules, costimulatory molecules, and cytokines. Mice were sensitized and challenged with ovalbumin (OVA) to induce asthma. They were repeatedly injected intranasally with γ‐PGA before and during the challenge period, and inflammation and structural remodelling of the airways were examined.</P><P><B>Results </B> γ‐PGA selectively signalled conventional DCs to activate NF‐κB and mitogen‐activated protein kinase, leading to the up‐regulation of CD86, CD40, and IL‐12, but not IL‐10 and IL‐6. These effects of γ‐PGA were dependent on TLR‐4 and independent of TLR‐2. Importantly, the intranasal administration of γ‐PGA to OVA‐sensitized/challenged mice reduced the airway hyperresponsiveness and allergic inflammation such as leucocyte influx, goblet cell hyperplasia, eosinophilia, and Th2 cytokine production. In addition to lowered IgE titres, the treatment of mice with γ‐PGA significantly reduced the multiplication and Th2 polarization of mediastinal lymph node T cells upon allergen‐specific restimulation. These anti‐asthmatic effects of γ‐PGA were also abolished in TLR‐4‐defective mice.</P><P><B>Conclusions and Clinical Relevance </B> Our data indicate that γ‐PGA activates DCs to favour Th1 cell induction through a TLR‐4‐dependent pathway and alleviates pathologic symptoms in a Th2‐biased asthmatic model. These findings highlight the potential of γ‐PGA for the treatment of asthma and other allergic disease in which Th2 polarization plays an important role.</P><P> <I>Cite this as</I>: K. Lee, S.‐H. Kim, H. J. Yoon, D. J. Paik, J. M. Kim and J. Youn, <I>Clinical & Experimental Allergy</I>, 2011 (41) 1143–1156.</P>

Structural insights into conserved l-arabinose metabolic enzymes reveal the substrate binding site of a thermophilic l-arabinose isomerase

Lee, Y.J.,Lee, S.J.,Kim, S.B.,Lee, S.J.,Lee, S.H.,Lee, D.W. North-Holland Pub ; Elsevier Science Ltd 2014 FEBS letters Vol.588 No.6

Structural genomics demonstrates that despite low levels of structural similarity of proteins comprising a metabolic pathway, their substrate binding regions are likely to be conserved. Herein based on the 3D-structures of the α/β-fold proteins involved in the ara operon, we attempted to predict the substrate binding residues of thermophilic Geobacillus stearothermophilusl-arabinose isomerase (GSAI) with no 3D-structure available. Comparison of the structures of l-arabinose catabolic enzymes revealed a conserved feature to form the substrate-binding modules, which can be extended to predict the substrate binding site of GSAI (i.e., D195, E261 and E333). Moreover, these data implicated that proteins in the l-arabinose metabolic pathway might retain their substrate binding niches as the modular structure through conserved molecular evolution even with totally different structural scaffolds.

Inhibitory effect of fenofibrate on neointima hyperplasia via G₀/G₁ arrest of cell proliferation

Lee, J.J.,Yu, J.Y.,Zhang, W.Y.,Kim, T.J.,Lim, Y.,Kwon, J.S.,Kim, D.W.,Myung, C.S.,Yun, Y.P. North-Holland ; Elsevier Science Ltd 2011 european journal of pharmacology Vol.650 No.1

We have previously reported that fenofibrate displayed a potent antithrombotic effect by the inhibition of platelet aggregation. The present study was designed to investigate the effects of fenofibrate on the neointimal hyperplasia and its possible molecular mechanism. Neointimal hyperplasia was measured in balloon-inflated-induced vascular injury model of male Sprague-Dawley rats and cell proliferation was measured in primary cultured rat aortic vascular smooth muscle cells (VSMCs). Fenofibrate-treated group showed a significant reduction in neointimal formation (0.07+/-0.04mm<SUP>2</SUP>) from the control (0.13+/-0.04mm<SUP>2</SUP>). Fenofibrate significantly inhibited platelet-derived growth factor (PDGF)-BB-induced cell counting and [<SUP>3</SUP>H]-thymidine incorporation into DNA. Fenofibrate suppressed the PDGF-BB-inducible progression through G<SUB>0</SUB>/G<SUB>1</SUB> to S phase of cell cycle. Moreover, fenofibrate inhibited not only phosphorylation of retinoblastoma (Rb) protein and expression of cyclin D/E, CDK 2/4 and proliferating cell nuclear antigen (PCNA) proteins but also mitogen-activated protein kinase (MAPK) signaling pathways such as ERK ½, p38 and JNK phosphorylation. In conclusion, the present study demonstrates that fenofibrate significantly inhibits neointimal formation via G<SUB>0</SUB>/G<SUB>1</SUB> arrest of PDGF-BB-induced cell proliferation in association with the inhibition of MAPK, which resulted in the downregulation of expressions of cyclin D/E, CDK 2/4 and PCNA proteins, suggesting that fenofibrate may be useful for individuals with a high risk of thrombotic or cardiovascular diseases.