• The Korean Journal of Physiology and Pharmacology
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• v.16 no.5
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• pp.349-353
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• 2012

Activated T cells express inhibitory receptors such as CTLA-4 that can downregulate immune responses. Blockade of or genetic deficiency in CTLA-4 can result in autoimmunity. Therefore, strategies to increase the inhibitory function of CTLA-4 may be attractive in settings of undesirable T cell responses such as autoimmunity or transplant rejection. We have tested the hypothesis that transgenic constitutive expression of CTLA-4 can further attenuate immune responses when compared with normal inducible expression. Our results indicate that transgenic expression of CTLA-4 in mouse T cells (CTLA-4-Tg T cells) results in reduced cell cycle progression and increased apoptosis of TCR-stimulated T cells. CTLA-4-Tg T cells display reduced T cell proliferation in an in vivo model of graft versus host disease (GVHD). These results further our understanding of how CTLA-4 can be manipulated to inhibit immune responses and may help development of new therapeutic strategies for clinical settings of autoimmunity and transplantation.

• IMMUNE NETWORK
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• v.11 no.5
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• pp.245-252
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• 2011

Antimicrobial peptides/proteins are ancient and naturally-occurring antibiotics in innate immune responses in a variety of organisms. Additionally, these peptides have been recognized as important signaling molecules in regulation of both innate and adaptive immunity. During mycobacterial infection, antimicrobial peptides including cathelicidin, defensin, and hepcidin have antimicrobial activities against mycobacteria, making them promising candidates for future drug development. Additionally, antimicrobial peptides act as immunomodulators in infectious and inflammatory conditions. Multiple crucial functions of cathelicidins in antimycobacterial immune defense have been characterized not only in terms of direct killing of mycobacteria but also as innate immune regulators, i.e., in secretion of cytokines and chemokines, and mediating autophagy activation. Defensin families are also important during mycobacterial infection and contribute to antimycobacterial defense and inhibition of mycobacterial growth both in vitro and in vivo. Hepcidin, although its role in mycobacterial infection has not yet been characterized, exerts antimycobacterial effects in activated macrophages. The present review focuses on recent efforts to elucidate the roles of host defense peptides in innate immunity to mycobacteria.

• Molecules and Cells
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• v.42 no.7
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• pp.503-511
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• 2019

As sessile organisms, plants have developed sophisticated system to defend themselves against microbial attack. Since plants do not have specialized immune cells, all plant cells appear to have the innate ability to recognize pathogens and turn on an appropriate defense response. The plant innate immune system has two major branches: PAMPs (pathogen associated molecular patterns)-triggered immunity (PTI) and effector-triggered immunity (ETI). The ability to discriminate between self and non-self is a fundamental feature of living organisms, and it is a prerequisite for the activation of plant defenses specific to microbial infection. Arabidopsis cells express receptors that detect extracellular molecules or structures of the microbes, which are called collectively PAMPs and activate PTI. However, nucleotidebinding site leucine-rich repeats (NB-LRR) proteins mediated ETI is induced by direct or indirect recognition of effector molecules encoded by avr genes. In Arabidopsis, plasmamembrane localized multifunctional protein RIN4 (RPM1-interacting protein 4) plays important role in both PTI and ETI. Previous studies have suggested that RIN4 functions as a negative regulator of PTI. In addition, many different bacterial effector proteins modify RIN4 to destabilize plant immunity and several NB-LRR proteins, including RPM1 (resistance to Pseudomonas syringae pv. maculicola 1), RPS2 (resistance to P. syringae 2) guard RIN4. This review summarizes the current studies that have described signaling mechanism of RIN4 function, modification of RIN4 by bacterial effectors and different interacting partner of RIN4 in defense related pathway. In addition, the emerging role of the RIN4 in plant physiology and intercellular signaling as it presents in exosomes will be discussed.

• Korean Journal of Agricultural Science
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• v.45 no.3
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• pp.365-378
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• 2018

Anthracnose caused by Colletotrichum gloeosporioides, which is one of the major diseases of red dates, causes severe damages in jujube (Zizyphus jujuba Miller) production in Korea. This study was done to evaluate the inhibition of anthracnose occurrence and pathogen growth by the treatment of environment-friendly materials such as a Bordeaux mixture and loess-sulfur mixture and by defense-response signaling in jujube. The in vitro test of the environment-friendly materials and signaling molecules that were routinely applied did not exhibit any antifungal activities against the pathogen for jujube anthracnose. The Bordeaux mixture and loess-sulfur mixture at a two-fold concentration showed inhibition zones that were 16.0 and 20.3 mm in diameter, respectively. In the pathogen inoculation test with detached jujube tree leaves, while treatment with the environment-friendly materials diluted by half showed no inhibition of lesion development, they did show inhibition of lesion development when they were routinely applied to the leaves. In detached jujube fruits inoculated with the pathogen, better suppressive effects by the treatment of the environment-friendly materials were seen in the fruits at a young stage rather than in the ripening stage. The in vivo test with jujube trees in pots showed that the treatment of salicylic acid (1 mM) resulted in the best suppressive effects against lesion development. The results suggest that it is possible to manage the incidence of anthracnose by the treatment of environment-friendly materials such as the Bordeaux and loess-sulfur mixtures and signaling chemicals such as ethephon, hydrogen peroxide, methyl jasmonate, and salicylic acid in jujube trees and fruits. Consequently, these findings suggest that environment-friendly materials and defense response signaling molecules could be used as suitable candidates for sustainable agrochemicals to manage anthracnose in jujube production.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.2
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• pp.18-23
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• 2016

Self-assembly of organic molecules is formed spontaneously on surfaces by electrostatic interaction with substrate. This research has shown that the self-assembly improves safety and handling tractability of high-energetic materials (HEMs). According to the recent study, control of the specific crystal size for reducing the internal defects is mightily important, because the internal defects are a factor in unstability of HEMs. In turn, we performed self-assembly of organic molecules and HEMs by using nano-sized HEMs, which were produced by drowing-out or milling/crystallization. Surface modification efficiency was decided by size distribution, zeta-potential, friction sensitivity and electrostatic charge.

• Molecules and Cells
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• v.25 no.3
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• pp.323-331
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• 2008

Plants are continually exposed to a variety of potentially pathogenic microbes, and the interactions between plants and pathogenic invaders determine the outcome, disease or disease resistance. To defend themselves, plants have developed a sophisticated immune system. Unlike animals, however, they do not have specialized immune cells and, thus all plant cells appear to have the innate ability to recognize pathogens and turn on an appropriate defense response. Using genetic, genomic and biochemical methods, tremendous advances have been made in understanding how plants recognize pathogens and mount effective defenses. The primary immune response is induced by microbe-associated molecular patterns (MAMPs). MAMP receptors recognize the presence of probable pathogens and evoke defense. In the co-evolution of plant-microbe interactions, pathogens gained the ability to make and deliver effector proteins to suppress MAMP-induced defense responses. In response to effector proteins, plants acquired R-proteins to directly or indirectly monitor the presence of effector proteins and activate an effective defense response. In this review we will describe and discuss the plant immune responses induced by two types of elicitors, PAMPs and effector proteins.

• Bulletin of the Korean Chemical Society
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• v.33 no.3
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• pp.855-861
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• 2012

A pioneering version of an on-line management system for high-energy molecules (MS-HEMs) was developed by the ADD and BMDRC in Korea. The current system can manage the physicochemical and explosive properties of virtual and existing HEMs. The on-line MS-HEMs consist of three main routines: management, calculation, and search. The management routine contains a user-friendly interface to store and manage molecular structures and other properties of the new HEMs. The calculation routine automatically calculates a number of compositional and topological molecular descriptors when a new HEM is stored in the MS-HEMs. Physical properties, such as the heat of formation and density, can also be calculated using group additivity methods. In addition, the calculation routine for the impact sensitivity can be used to obtain the safety nature of new HEMs. The impact sensitivity was estimated in a knowledge-based manner using in-house neural network code. The search routine enables general users to find an exact HEM and its properties by sketching a 2D chemical structure, or to retrieve HEMs and their properties by giving a range of properties. These on-line MS-HEMs are expected be powerful tool for deriving novel promising HEMs.

• Bulletin of the Korean Chemical Society
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• v.32 no.12
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• pp.4341-4346
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• 2011

Impact sensitivity, one of the most important screening factors for novel high energy density materials (HEDMs), was predicted by use of quantitative structure-property relationship (QSPR) based on the electrostatic potential (ESP) values calculated on the van der Waals molecular surface (MSEP). Among various 3D descriptors derived from MSEP, we utilized total and positive variance of MSEP, and devised a new QSPR equation by combining three other parameters. We employed 37 HEDMs bearing a benzene scaffold and nitro substituents, which were also utilized by Rice and Hare. All the molecular structures were optimized at the B3LYP/6-31G(d) level of theory and confirmed as minima by the frequency calculations. Our new QSPR equation provided a good result to predict the impact sensitivities of the molecules in the training set including zwitterionic molecules.

• Molecules and Cells
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• v.41 no.1
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• pp.27-34
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• 2018

The cytoplasm in mammalian cells is a battlefield between the host and invading microbes. Both the living organisms have evolved unique strategies for their survival. The host utilizes a specialized autophagy system, xenophagy, for the clearance of invading pathogens, whereas bacteria secrete proteins to defend and escape from the host xenophagy. Several molecules have been identified and their structural investigation has enabled the comprehension of these mechanisms at the molecular level. In this review, we focus on one example of host autophagy and the other of bacterial defense: the autophagy receptor, NDP52, in conjunction with the sugar receptor, galectin-8, plays a critical role in targeting the autophagy machinery against Salmonella; and the cysteine protease, RavZ secreted by Legionella pneumophila cleaves the LC3-PE on the phagophore membrane. The structure-function relationships of these two examples and the directions of future research will be discussed.

• Molecules and Cells
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• v.24 no.2
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• pp.153-166
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• 2007

The syndecan family of heparan sulfate proteoglycans is expressed on the surface of all adherent cells. Syndecans interact with a wide variety of molecules, including growth factors, cytokines, proteinases, adhesion receptors and extracellular matrix components, through their heparan sulfate chains. Recent studies indicate that these interactions not only regulate key events in development and homeostasis, but also key mechanisms of the host inflammatory response. This review will focus on the molecular and cellular aspects of how syndecans modulate tissue injury and inflammation, and how syndecans affect the outcome of inflammatory diseases in vivo.