PLAG Exerts Anti-Metastatic Effects by Interfering with Neutrophil Elastase/PAR2/EGFR Signaling in A549 Lung Cancer Orthotopic Model.

The effectiveness of chemotherapy and radiotherapy to treat lung cancer is limited because of highly metastatic nature. Novel strategies and drugs to attenuate metastatic activity are urgently required. In this study, red fluorescence proteins (RFP)-labeled A549 human lung cancer cells were orthotopically implantation, where they developed primary tumors. Metastasis in brain and intestines were reduced by up to 80% by treatment with 100 mpk 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) compared with that in control mice. PLAG treatment also reduced the migration of the primary tumors. Interestingly, substantial neutrophil infiltration was observed in the tumors in control mice. The neutrophil contribution to A549 cell metastatic activity was examined in in vitro co-culture system. Metastatic activity could be achieved in the A549 cells through epidermal growth factor receptor (EGFR) transactivation mediated by protease activating receptor 2 (PAR2) receptor. Neutrophil elastase secreted from tumor-infiltrating neutrophils stimulated PAR2 and induced EGFR transactivation. However, this transactivation was inhibited by inducing PAR2 degradation following PLAG treatment and metastatic activity was effectively inhibited. PLAG attenuated cancer metastatic activity via modulated PAR2/EGFR transactivation by accelerating PAR2 degradation. These results suggest PLAG as potential therapeutic agent to combat tumor metastasis via regulating the activation signal pathway of PAR2 by tumor infiltrate-neutrophils.

PLAG enhances macrophage mobility for efferocytosis of apoptotic neutrophils via membrane redistribution of P2Y2.

Neutrophil activity, including trapping of damage-associated molecular patterns by neutrophil extracellular traps (NETs), is an important response to microbial infection. Most activated neutrophils commit to apoptosis and are removed by activated macrophages in the process of efferocytosis. Improper clearance of apoptotic neutrophils often causes an unnecessary and exaggerated immune response and subsequent chronic inflammation. Effective macrophage mobility toward activated neutrophils, which is triggered by binding of 'find-me' signals to receptors such as P2Y2, is a crucial step for the timely clearance of apoptotic neutrophils. In this paper, we investigated the effect of 1-palmitoyl-2-linoleoyl-3-acetyl-rac-glycerol (PLAG) on efferocytosis and the underlying molecular mechanisms. In a coculture of apoptotic neutrophils with macrophages, PLAG treatment increased levels of efferocytosis of apoptotic neutrophils. PLAG induced faster translocation of P2Y2 from lipid rafts to nonlipid raft plasma membrane domains in macrophages. This repositioning of P2Y2 enables the polarization of the cytoskeleton by association of the receptor with cytoskeletal proteins such as α-tubulin and actin to improve the mobility of macrophages. The formation of vesicular, chylomicron-like structures by PLAG was a prerequisite for the induction of this macrophage activity, as none of these effects was seen when the vesicle receptor GPIHBP1 was absent. Taken together, these data showed that PLAG is a powerful immune resolvent that triggers the prompt clearance of apoptotic neutrophils by enhanced efferocytosis activity. PLAG could therefore be an effective lipid-based efferocytosis enhancer for use as a therapeutic drug to prevent inflammatory disease caused by uncontrolled immune responses.

Molecular identification of mealybugs (Hemiptera: Pseudococcidae) found on Korean pears.

Mealybugs are under a strict regulation at foreign trades of agricultural products because they are one of the most economically damaging groups of insects on food crops and ornamental plants. However, the absence of morphological characteristics enabling the discrimination of early life stages often cause a significant delay or rejection of a shipment when infested fruit is discovered, causing significant economic loss. A polymerase chain reaction-based method for species identification was developed for six mealybug species known to infest Korean pears including two regulated insects, Planococcus kraunhiae (Kuwana) and Crisicoccus matsumotoi (Siraiwa). Six sets of species-specific primers were designed based on the sequence comparison of the internal transcribed spacer 1 and 2 regions. Efficiency tests against 29 mealybug samples showed that this method could effectively discriminate different mealybug species regardless of their developmental stages. Blind tests against 11 field collected mealybug nymph samples indicated that a single polymerase chain reaction is enough to discriminate unidentified mealybugs collected on Korean pears. This new method will facilitate trade and export requirements, as well as identify the species at any stage of mealybug intercepted.

Development of patatin knockdown potato tubers using RNA interference (RNAi) technology, for the production of human-therapeutic glycoproteins.

BACKGROUND: Patatins encoded by a multi-gene family are one of the major storage glycoproteins in potato tubers. Potato tubers have recently emerged as bioreactors for the production of human therapeutic glycoproteins (vaccines). Increasing the yield of recombinant proteins, targeting the produced proteins to specific cellular compartments, and diminishing expensive protein purification steps are important research goals in plant biotechnology. In the present study, potato patatins were eliminated almost completely via RNA interference (RNAi) technology to develop potato tubers as a more efficient protein expression system. The gene silencing effect of patatins in the transgenic potato plants was examined at individual isoform levels. RESULTS: Based upon the sequence similarity within the multi-gene family of patatins, a highly conserved target sequence (635 nts) of patatin gene pat3-k1 [GenBank accession no. DQ114421] in potato plants (Solanum tuberosum L.) was amplified for the construction of a patatin-specific hairpin RNAi (hpRNAi) vector. The CaMV 35S promoter-driven patatin hpRNAi vector was transformed into the potato cultivar Desiree by Agrobacterium-mediated transformation. Ten transgenic potato lines bearing patatin hpRNA were generated. The effects of RNA interference were characterized at both the protein and mRNA levels using 1D and 2D SDS/PAGE and quantitative real-time RT-PCR analysis. Dependent upon the patatin hpRNAi line, patatins decreased by approximately 99% at both the protein and mRNA levels. However, the phenotype (e.g. the number and size of potato tuber, average tuber weight, growth pattern, etc.) of hpRNAi lines was not distinguishable from wild-type potato plants under both in vitro and ex vitro growth conditions. During glycoprotein purification, patatin-knockdown potato tubers allowed rapid purification of other potato glycoproteins with less contamination of patatins. CONCLUSION: Patatin-specific hpRNAi effectively suppressed the expression of a majority of patatin variants in potato tubers via the specific degradation of individual mRNAs of the patatin multi-gene family. More importantly, patatin-knockdown potato tubers appear to be an ideal host for the production of human therapeutic glycoproteins, because they eventually allow fast, easy purification of recombinant proteins, with less contamination from potato glycoprotein patatins.

Elevated H(2)O (2) production via overexpression of a chloroplastic Cu/ZnSOD gene of lily (Lilium oriental hybrid 'Marco Polo') triggers ethylene synthesis in transgenic potato.

Transgenic potato plants (SS2 and SS4) that overexpressed a chloroplastic copper/zinc superoxide dismutase lily gene were utilized as an H(2)O(2)-inducible system in order to study the role of H(2)O(2) as a signaling molecule in the biosynthesis of ethylene. SS2 and SS4 plants grown in vitro under sealed microenvironment (SME) conditions displayed anomalous phenotypes including reduction of stem elongation, radial stem growth, and promotion of root hair formation in the generated root, which were similar to ethylene-induced responses. In addition, SS4 plants showed severe vitrification in developing leaves and elevated ethylene production under SME conditions. After the ethylene action inhibitor AgNO(3), 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (ACO) inhibitor CoCl(2), and ACC synthase inhibitor L -aminoethoxyvinylglycine were added to the growth media, the anomalous phenotypes in SS4 plants reverted to their normal phenotype with a concurrent decrease in ethylene production. Northern blot analysis showed that ACO transcripts in SS4 plants were constantly at high levels under normal and SME conditions, indicating that a high level of H(2)O(2) in SS4 plants up-regulates ACO transcripts. Moreover, the direct treatment of H(2)O(2) in potato plants confirmed the elevated expression of the ACO gene. Taken together, these data suggest that the high concentration of H(2)O(2) in transgenic potato plants stimulates ethylene biosynthesis by activating ACO gene expression.

Superoxide anion regulates plant growth and tuber development of potato.

A higher concentration of H2O2 was detected in the sense transgenic potato plant (SS4) with the lily chCu,ZnSOD sequence, whereas higher levels of O2(-) was detected in the antisense transgenic plant (SA1) than the WT plant. The elongation growth in SA1 was significantly inhibited by treatment with diphenyleneiodonium, an inhibitor of O2(-) generation, and promoted in the SS4 on treatment with herbicide methyl viologen, a generator of apoplastic O2(-) . Higher concentrations of GAs were detected during plant growth and the early stage of tuberization in SA1. Complete recovery of the above elongation growth and microtuberization pattern in transgenic plants following treatment of GA(3) or an inhibitor of gibberellin synthesis, paclobutrazol, indicate that these changes were mainly caused by active GA levels. In conclusion, a specific ROS (O2(-) ) acts as a signal transducer via GA biosynthetic pathways for the regulation of plant growth and tuber development of potato.

Gene cloning, sequencing, and expression of an esterase from Acinetobacter lwoffii I6C-1.

The esterase-encoding gene, estA, was cloned from Acinetobacter lwoffii I6C-1 genomic DNA into Escherichia coli BL21(DE3) with plasmid vector pET-22b (pEM1). pEM1 has a 4.4-kb EcoRI insert that contained the complete estA gene. A 2.4-kb AvaI- SphI DNA fragment was subcloned (pEM3) and sequenced. estA gene encodes a protein of 366 amino acids (40,687 Da) with a pI of 9.17. The EstA signal peptide was 31 amino acids long, and the mature esterase sequence is 335 amino acids long (37.5 kDa). The conserved catalytic serine residue of EstA is in position 210. The EstA sequence was similar to that of the carboxylesterase from Acinetobacter calcoaceticus (75% identity, 85% similarity), Archaeoglobus fulgidus (37% identity, 59% similarity), and Mycobacterium tuberculosis (35% identity, 51% similarity). These enzymes contained the conserved motif G-X(1)-S-X(2)-G carrying the active-site serine of hydrolytic enzyme. The EstA activity in A. lwoffii I6C-1 remains constant throughout the stationary phase, and the activity in E. coil BL21 (DE3) with pEM1 was similar to A. lwoffii I6C-1.