• International Journal of Industrial Entomology and Biomaterials
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• v.37 no.2
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• pp.95-99
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• 2018

In insect defense system, antimicrobial peptides (AMPs) are one of important biological molecules to survive in a variety of environments. Insect can synthesize AMPs to protect against invading pathogens in humoral immune response. Taking more advantage of biological antimicrobial molecules, we report antibacterial activity of two cecropin type peptides, cecropin and moricin, isolated from the silkworm against four salmonella species. In this work, we purified antimicrobial candidate peptides (AMCP) from the extracts of immune challenged silkworm larval hemolymph by two-step chromatographic purification procedure, cation exchange and gel permeation chromatography. The molecular weights of purified peptides were estimated to be about 4 ~ 5 kDa by Tricin SDS-PAGE analysis, and identified as silkworm cecropin and moricin by NCBI BLAST homology search with their N-terminal amino acid sequences. As antibacterial activity assay, the purified peptides showed stronger antibacterial activity against Salmonella pathogens with an MIC value of $1{\sim}4{\mu}g/mL$. Therefore two cecropin type peptides purified from the silkworm will be valuable potential materials for development of new natural antibiotics.

• BMB Reports
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• v.46 no.5
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• pp.282-287
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• 2013

Cecropin A and papiliocin are novel 37-residue cecropin-like antimicrobial peptides isolated from insect. We have confirmed that papiliocin possess high bacterial cell selectivity and has an ${\alpha}$-helical structure from $Lys^3$ to $Lys^{21}$ and from $Ala^{25}$ to $Val^{35}$, linked by a hinge region. In this study, we demonstrated that both peptides showed high antimicrobial activities against multi-drug resistant Gram negative bacteria as well as fungi. Interactions between these cecropin-like peptides and phospholipid membrane were studied using CD, dye leakage experiments, and NMR experiments, showing that both peptides have strong permeabilizing activities against bacterial cell membranes and fungal membranes as well as $Trp^2$ and $Phe^5$ at the N-terminal helix play an important role in attracting cecropin-like peptides to the negatively charged bacterial cell membrane. Cecropin-like peptides can be potent peptide antibiotics against multi-drug resistant Gram negative bacteria and fungi.

• International Journal of Industrial Entomology and Biomaterials
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• v.17 no.1
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• pp.131-135
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• 2008

A cDNA encoding a defensin-like peptide (Protaetiamycine) from the larvae of a beetle, Protaetia brevitarsis was cloned. The DNAs encoded the deduced propeptide of 79 amino acid residues with the predicted molecular weight of 8.4 kDa and PI of 8.24. Overall amino acid sequence of this protein has 39% similarity to that of Rhodnius prolixus defensin, 43% similarity to that of Acalolepta luxuriosa defensin, and 72% similarity to that of Oryctes rhinoceros defensin, suggesting that this gene is an insect defensin. In an attempt to apply the anti-bacterial peptide to the development of therapeutic agents, a 12-mer peptide amidated at its C-terminus, ACAAHCLAIGRG-$NH_2$ (Ala55-Lys66-$NH_2$, 12Pbn) was synthesized. This peptide showed some antifungal activity against Candida albicans. To increase antifungal activity, six 9-mer peptides were synthesized by modifying amino acid sequences of 12Pbn fragment. Among these peptides, 9Pbm3-9Pbm6 exhibited strong activity compared with Cecropin B and mellitin.

• BMB Reports
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• v.42 no.8
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• pp.506-510
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• 2009

The Toll signalling pathway in invertebrates is responsible for defense against Gram-positive bacteria and fungi, leading to the expression of antimicrobial peptides via NF-$\kappa$B-like transcription factors. Gram-negative binding protein 3 (GNBP3) detects beta-1,3-glucan, a fungal cell wall component, and activates a three step serine protease cascade for activation of the Toll signalling pathway. Here, we showed that the recombinant N-terminal domain of Tenebrio molitor GNBP3 bound to beta-1,3-glucan, but did not activate down-stream serine protease cascade in vitro. Reversely, the N-terminal domain blocked GNBP3-mediated serine protease cascade activation in vitro and also inhibited beta-1,3-glucan-mediated antimicrobial peptide induction in Tenebrio molitor larvae. These results suggest that the N-terminal GNBP homology domain of GNBP3 functions as a beta-1,3-glucan binding domain and the C-terminal domain of GNBP3 may be required for the recruitment of immediate down-stream serine protease zymogen during Toll signalling pathway activation.

• Journal of Life Science
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• v.32 no.1
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• pp.23-28
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• 2022

CopA3 (LLCIALRKK), an antimicrobial peptide isolated from the Korean dung beetle, has been shown to suppress apoptosis in various cell types. CopA3 inhibits not only bacterial toxin-induced colonocyte apoptosis but also 6-hydroxy dopamine-induced neural cell apoptosis. Our recent study revealed that CopA3 directly binds to caspases (key regulators of apoptosis) and inhibits the proteolytic cleavage required for their activation. But molecular mechanisms underlying CopA3-mediated inhibition of apoptosis in multiple cell types remain unknown. Here we assessed possible effects of CopA3 on expression of survivin, which is known to inhibit apoptosis. In HT29 human colonocytes, CopA3 exposure markedly upregulated survivin expression in a concentration- and time-dependent manner. RT-PCR revealed that CopA3-mediated upregulation of survivin was attributable to increased gene transcription, and further showed that CopA3 also increased expression of Sp1, one of many transcription factors known to be involved in transcription of the survivin gene. Notably, blocking Sp1 by treatment with the Sp1 inhibitor, tolfenamic acid, significantly reduced CopA3-mediated upregulation of survivin. These results collectively suggest that CopA3 induces Sp1 expression, which in turn is involved in upregulation of survivin in human colonocytes. These novel findings establish another pathway for explaining the anti-apoptotic effects of CopA3 against various cellular apoptosis systems.

• Journal of Life Science
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• v.29 no.11
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• pp.1218-1226
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• 2019

The white-spotted flower chafer Protaetia brevitarsis seulensis is a medicinally beneficial and important edible insect species. We previously performed an in silico analysis of the Protaetia brevitarsis seulensis transcriptome to identify putative antimicrobial peptides and then tested their antimicrobial and hemolytic activities. These peptides had potent antimicrobial activities against bacteria and yeast without inducing hemolysis. In the present study, the cationic antimicrobial peptide, protaetiamycine 2, was selected for further assessment of its anti-inflammatory properties in mouse macrophage Raw264.7 cells. Protaetiamycine 2 treatment of Raw264.7 cells suppressed LPS-induced nitric oxide production and reduced the expression of inducible nitric oxide synthase and cyclooxygenase-2, as determined by real-time PCR and western blotting. The expression of proinflammatory cytokines ($TNF-{\alpha}$, IL-6, and $IL-1{\beta}$) was also attenuated through the MAPKs and $NF-{\kappa}B$ signaling. We also confirmed that protaetiamycine 2 bound to bacterial cell membranes by a specific interaction with LPS. Collectively, these data obtained from LPS-induced Raw264.7 cells indicated that protaetiamycine 2 could have both antimicrobial and anti-inflammatory properties.

• Journal of Life Science
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• v.30 no.12
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• pp.1078-1084
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• 2020

Protaetia brevitarsis seulensis is an insect belonging to the order Coleoptera. This insect is reported to contain large amounts of physiologically active substances useful for liver protective effect and improvements in blood circulation as well as a broad source of edible protein. Antimicrobial peptides (AMPs) are found in a variety of species, from microorganisms to mammals, and play an important role in the innate immune systems of living things. Microglia are the main source of proinflammatory cytokines and nitric oxide (NO) in the central nervous system. Activated microglia secrete large amounts of neuroinflammatory mediators (e.g., TNF-α, NO, and ROS), which are the main cause of neuronal cell death. In the present study, we investigated the inhibitory effect of Protaetiamycine 6 (PKARKLQKLSAYKTTLRN-NH2), an AMP derived from Protaetia brevitarsis seulensis, on LPS-induced neuroinflammation in BV-2 microglia. Protaetiamycine 6 significantly inhibited NO production without cytotoxicity and decreased the expression levels of inducible NO synthase and cyclooxygenase-2. In addition, Protaetiamycine 6 also reduced the production of neuroinflammatory cytokines on activated BV-2 microglia. These results suggest that Protaetiamycine 6 could be a good source of functional substance to prevent neuroinflammation and neurodegenerative diseases.

• Biotechnology and Bioprocess Engineering:BBE
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• v.11 no.5
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• pp.442-448
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• 2006

Human lactoferrin (hLf) is an iron-binding glycoprotein that has been considered to play many biological roles in the human, including the stimulation of the immune system, antimicrobial and anti-inflammatory effects, and regulation of iron absorption. We generated transgenic Siberian ginseng (Acanthopanax senticosus) cell cultures producing a functional hLf protein using the signal peptide sequence from the endoplasmic reticulum and driven by an oxidative stress-inducible SWPA2 promoter which is highly expressed in plant cell cultures. The production of hLf increased proportionally to cell growth and showed a maximal level (up to 3.6% of total soluble protein) at the stationary phase in suspension cultures. Full-length hLf protein was identified by immunoblot analysis in transgenic cell cultures of Siberian ginseng. Recombinant hLf (rhLf) was purified from suspension cells of Siberian ginseng by ammonium sulfate precipitation, cation-exchange and gel filtration chromatography. N-terminal sequences of rhLf were identical to native hLf (nhLf). The overall monosaccharide composition of rhLf showed the presence of plant specific xylose while sialic acid is absent. Antibacterial activity of purified rhLf was higher than that of nhLf. Taken together, we anticipate that medicinal Siberian ginseng cultured cells, as demonstrated by this study, will be a biotechnologically useful source for commercial production of functional hLf not requiring further purification.