Seong-Min Cho

Caspase-8 controls the secretion of inflammatory lysyl-tRNA synthetase in exosomes from cancer cells

Aminoacyl-tRNA synthetases (ARSs), enzymes that normally control protein synthesis, can be secreted and have different activities in the extracellular space, but the mechanism of their secretion is not understood. This study describes the secretion route of the ARS lysyl-tRNA synthetase (KRS) and how this process is regulated by caspase activity, which has been implicated in the unconventional secretion of other proteins. We show that KRS is secreted from colorectal carcinoma cells within the lumen of exosomes that can trigger an inflammatory response. Caspase-8 cleaved the N-terminal of KRS, thus exposing a PDZ-binding motif located in the C terminus of KRS. Syntenin bound to the exposed PDZ-binding motif of KRS and facilitated the exosomic secretion of KRS dissociated from the multi-tRNA synthetase complex. KRS-containing exosomes released by cancer cells induced macrophage migration, and their secretion of TNF-&agr; and cleaved KRS made a significant contribution to these activities, which suggests a novel mechanism by which caspase-8 may promote inflammation.

Solvent effect of the fibrillar morphology on the power conversion efficiency of a polymer photovoltaic cell in a diffusive heterojunction

We describe the solvent-dependent morphology of a conjugated polymer, poly(3-hexylthiophene) (P3HT) interfaced with [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and the evolution of the resulting inter-connected fibrillar structure (ICFS) in a diffusive bilayer heterojunction (DBHJ). It is found that the fibrillar structure of the P3HT is preferentially developed in a poor solvent and less soluble than an amorphous structure and the ICFS improves the power conversion efficiency (ηp) significantly. Among four different solvents chlorobenzene, dichlorobenzene, chloroform and p-xylene studied, p-xylene results in ηp ≈ 3% whereas chlorobenzene yields only 0.5%. This indicates clearly that the formation of the ICFS plays a critical role to induce high exciton generation/dissociation to produce spatially uninterrupted pathways for the charge transport, and to enhance ηp of a polymer photovoltaic device in the DBHJ configuration. (Some figures may appear in colour only in the online journal)

Viewing Angle Switchable Liquid Crystal Display with Double Layers Separated by an Interlayer Support

We demonstrate a viewing angle switchable (VAS) liquid crystal display (LCD) with an interlayer support fabricated by imprinting lithography. The interlayer support is embedded in a single cell to separate two differently aligned LC layers, one of which is a primary layer for displaying images and the other is a complementary layer for switching viewing angles. Our VAS LC cell shows two viewing ranges that can be switched between ±40 and ±70°. Moreover, our method of using an interlayer support results in a reduction in the panel thickness and weight by 40% compared with the panel stacking method.

Novel wide viewing liquid crystal display with improved off-axis image quality in a twisted nematic configuration

We developed a novel twisted nematic (TN) liquid crystal display (LCD) having wide viewing angle characteristics through the reduction of the residual liquid crystal phase retardation at oblique angles using an embedded diffusing unit. Compared to a conventional TN panel, this embedded approach provides extended isocontrast contours by more than ±10 deg at a contrast ratio of 100:1 along the horizontal direction and a wide region free of grayscale inversion by a factor of 2 along the vertical direction. Moreover, the off-axis image distortions in our novel LCD are improved by 50% compared to those in a film-compensated TN LCD.

Evaluation on Anti-fungal Activity and Synergy Effects of Essential Oil and Their Constituents from Abies holophylla

This study was to investigate the antifungal activity of A. holophylla essential oil against dermatophytes, such as Epidermophyton floccosum, Trichophyton mentagrophytes and Trichophyton rubrum, and to determine the potential effective compound as dermatitis treatment. To evaluate the potential antifungal activities of A. holophylla essential oil and its fractions, paper disc diffusion and agar dilution method tested with morphological observation. Also, their major constituents were analyzed by GC/MS. To determine synergic effects of active ingredient from A. holophylla essential oil were carried out by checkerboard microtiter plate testing. The morphological changes of the dermatophytes exposed to active fraction G4 were observed by electron microscopes. As the results, the highest activities were identified in the fraction containing -bisabolol. A mixture of -bisabolol and bornyl acetate showed the synergy effects, expressing high potential effects. Also, morphological observation using electron microscopes showed a dramatic changes of cell membrane of E. floccosum and T. rubrum exposed to fraction G4 containing -bisabolol. In conclusion, A. holophylla essential oil and its constituents were expected to be used as antifungal agent or raw material for dermatitis therapy.

High-brightness and wide-view transflective liquid crystal display with two in-cell imprinted optical films in an inverse-twisted-nematic geometry

An inverse-twisted-nematic (ITN) transflective (TRF) liquid crystal (LC) display, where two imprinted optical films (IOFs) with surface microstructures are embedded was developed. One of the IOFs serves as an in-cell patterned retarder with multi-optic axes, and the other behaves as a viewing-angle enhancement film. In the presence of an applied voltage, the surface microstructures on the IOFs provide the spontaneous twist of the LC from a vertically aligned state to a 90° twisted-nematic (TN) state in the transmissive part, and to a 45° TN state in the reflective part. The developed ITN TRF LC display exhibits high transmission and reflectance, fast response, and wide-viewing characteristics, along with achromaticity.

Adhesive-Transfer Bonding Technique for Flexible Liquid Crystal Displays with High Mechanical Stability

We report on an adhesive-transfer bonding technique for improving mechanical stability of a flexible liquid crystal display (LCD) with an elastomer substrate. Permanent adhesion between an elastomer substrate and a plastic substrate is generated through thermal cross-linking of a curing agent prepared on the elastomer substrate by precise stamping. Our flexible LCD assembled using the adhesive-transfer bonding technique is found to show excellent mechanical stability in a highly bent environment.

Fabrication of a Dual-Gap Substrate Using the Replica-molding Technique for Transflective Liquid Crystal Displays

Abstract A replica‐molding method of fabricating a dual‐gap substrate for transflective liquid crystal (LC) displays is demonstrated. The dual‐gap substrate provides homeotropic alignment for the LC molecules without any surface treatment and embedded bilevel microstructure on one of the two surfaces to maintain different cell gaps between the transmissive and reflective subpixels. The proposed transflective LC cell shows no electro‐optic disparity between two subpixels and reduces the panel thickness and weight by 30% compared to the conventional transflective LC cell, which has two glass substrates.

Exosomal secretion of truncated cytosolic lysyl-tRNA synthetase induces inflammation during cell starvation

Previous work by Kim, et al. (2017) unveiled that lysyl-tRNA synthetase (KRS) is secreted through a mechanism involving syntenin-containing exosomes. They described how KRS, commonly known as part of the translational machinery in the cytoplasm, is secreted into the extracellular space where it induces inflammation. First, KRS secretion is triggered by starvation conditions. The increase in caspase-8 levels during starvation is responsible for proteolysis and generation of the N-terminal truncated form of KRS, and this event is required for KRS dissociation from the multi-synthetase complex (MSC). N-terminal cleavage of KRS eventually leads to a conformational change that allows its interaction with the C-terminal PDZ binding motif of syntenin and subsequent exosome biogenesis. The KRS-syntenin complex translocates to multivesicular bodies (MVBs) that originate from endosomes involved with intraluminal vesicle (ILVs). MVBs are transporters for the secretion of cellular contents into the extracellular space. Syntenin localizes intraluminal vesicles within endosomal membranes. The KRS-syntenin complex transfers on to intraluminal vesicles in MVBs. MVBs are translocated to the plasma membrane for ILV secretion mediated by Rab family proteins. Once KRS exosomes are secreted, their membranes are eventually ruptured by proteases and KRS is released from the exosomes where it can act as an inflammatory cytokine in the extracellular space. Secreted KRS triggers macrophage/neutrophil migration and induces inflammation.

Integrated polymer solar cells in serial architecture with patterned charge-transporting MoOx for miniature high-voltage sources

We develop miniature high-voltage sources from polymer solar cells (PSCs) with charge-transporting molybdenum oxide (MoOx) integrated in a serial architecture through sacrificial layer (SL)-assisted patterning. The MoOx layer, being patterned by the lift-off process of the SL of a hydrophobic fluorinated-polymer, as a hole transporting layer plays a critical role on the reduction of the dark current and the increase of a high open circuit voltage of an integrated PSC array. The underlying mechanism lies primarily on the elimination of the lateral charge pathways in the MoOx layer in the presence of the electrode interconnection. Two miniature voltage sources consisting of 20 PSCs and 50 PSCs are demonstrated in the operation of a liquid crystal display and an organic field-effect transistor, respectively. Our SL-assisted integration approach will be directly applicable for implementing the self-power sources made of the PSCs into a wide range of the electronic and optoelectronic devices.