Nicorandil reversed homocysteine-induced coronary microvascular dysfunction via regulating PI3K/Akt/eNOS pathway.

OBJECTIVE: Nicorandil exerts a protective effect against coronary microvascular dysfunction in acute myocardial infarction (AMI) patients. However, the mechanism and effect of nicorandil in hyperhomocysteinemia (HHcy) AMI patients remain unclear. METHODS: C57/BL6 mice with mild to moderate HHcy and human coronary artery endothelial cells (HCAECs) cotreated with HHcy (1 mmol/L) for 24 h and hypoxia for 6 h were selected as models. Small animal ultrasound detection was used to compare cardiac function. CD31 immunofluorescence staining and tomato lectin staining were used to assess the number of microcirculation changes in vivo. MTT, tube formation and western blotting assays were used to evaluate the effect of nicorandil on HCAECs and the PI3K/Akt/eNOS pathway. RESULTS: The results showed that nicorandil improved cell viability and p-PI3K/PI3K, p-Akt/Akt, and p-eNOS/eNOS expression in the vitro HHcy and hypoxia models. The beneficial effects of nicorandil on HCAECs could be inhibited by the phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 and the nitric oxide synthase (NOS) inhibitor L-NAME. In vivo, nicorandil improved the left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) in the post-HHcy + MI model, and the levels of CD31 and tomato lectin expression were higher in the nicorandil treatment group. The effectiveness of nicorandil was inhibited in the PI3K and L-NAME groups. CONCLUSION: The results suggest that nicorandil improves Hcy-induced coronary microvascular dysfunction through the PI3K/Akt/eNOS signalling pathway.

Primary sensory neurons expressing tropomyosin receptor kinase A in the rat trigeminal ganglion.

Tropomyosin receptor kinase A (trkA), a high affinity receptor for nerve growth factor (NGF), has been implicated in neuronal survival, neurite outgrowth and inflammatory pain. So far, the characterization of the primary sensory neurons that express trkA, and are thus potentially affected by NGF, has remained incomplete. The goal of this study was to investigate the trkA-expressing neurons and fibers in the rat trigeminal ganglion and its sensory root using light- and electron-microscopic immunohistochemistry and quantitative analysis. TrkA-immunopositive (+) trigeminal neurons varied from small to large. Double immunofluorescent staining showed that about 28%, 33% and 3% of the trkA(+) neurons coexpressed SP, CGRP and IB4, respectively. About 11% of the trkA(+) neurons also coexpressed parvalbumin. Electron microscopy revealed that trkA was expressed in all types of fibers: While the large majority of the trkA(+) fibers were unmyelinated (35.3%) and small myelinated (<20 µm2 in cross-sectional area; 45.5%), a still considerable fraction (19.2%) was large myelinated. These findings indicate that all types of trigeminal neurons (ones with unmyelinated, small myelinated or large myelinated fibers) may be regulated by NGF/trkA signaling.

Expression profiling of the Dolichos lablab lectin during germination and development of the seed.

The temporal expression of the field bean (Dolichos lablab) galactose specific lectin, DLL-II, during germination, post-germination and seed development was evaluated using Native-PAGE followed by activity staining, immunodetection and quantitative Real Time PCR (qPCR). A rapid and steep decline in the polyphenol oxidase (PPO) and hemagglutinating activity during the initial stages of germination, which did not correlate with the slow decline in total protein was observed. During post germination period, PPO and hemagglutination activities were negligible, whereas a rapid resorption of the protein was evident. These results suggest that DLL-II is not a storage protein. The presence of mRNA in the quiescent seed and initial stages of germination are indicative of a very stable mRNA. DLL-II was expressed in high copies during seed development and increased dramatically between 10 and 20 days after flowering (DAF), suggesting a switch over stage in DLL-II expression. Transcript levels reached a maximum at the mature stage of seed development. Among the non-seed tissues examined, root showed the highest level. The high affinity binding to kinetin and indole acetic acid, the key hormones that regulate root development and its vascular differentiation add a new dimension to the physiological role of DLL-II in the seed. This finding, coupled with the PPO and hemagglutinating activity makes DLL-II, truly a multifunctional protein.

Frutapin, a lectin from Artocarpus incisa (breadfruit): cloning, expression and molecular insights.

Artocarpus incisa (breadfruit) seeds contain three different lectins (Frutalin, Frutapin (FTP) and Frutackin) with distinct carbohydrate specificities. The most abundant lectin is Frutalin, an α-D-galactose-specific carbohydrate-binding glycoprotein with antitumour properties and potential for tumour biomarker discovery as already reported. FTP is the second most abundant, but proved difficult to purify with very low yields and contamination with Frutalin frustrating its characterization. Here, we report for the first time high-level production and isolation of biologically active recombinant FTP in Escherichia coli BL21, optimizing conditions with the best set yielding >40 mg/l culture of soluble active FTP. The minimal concentration for agglutination of red blood cells was 62.5 µg/ml of FTP, a process effectively inhibited by mannose. Apo-FTP, FTP-mannose and FTP-glucose crystals were obtained, and they diffracted X-rays to a resolution of 1.58 (P212121), 1.70 (P3121) and 1.60 (P3121) Å respectively. The best solution showed four monomers per asymmetric unit. Molecular dynamics (MD) simulation suggested that FTP displays higher affinity for mannose than glucose. Cell studies revealed that FTP was non-cytotoxic to cultured mouse fibroblast 3T3 cells below 0.5 mg/ml and was also capable of stimulating cell migration at 50 µg/ml. In conclusion, our optimized expression system allowed high amounts of correctly folded soluble FTP to be isolated. This recombinant bioactive lectin will now be tested in future studies for therapeutic potential; for example in wound healing and tissue regeneration.

Heterologous expression of an α-amylase inhibitor from common bean (Phaseolus vulgaris) in Kluyveromyces lactis and Saccharomyces cerevisiae.

BACKGROUND: Phaseolamin or α-amylase inhibitor 1 (αAI) is a glycoprotein from common beans (Phaseolus vulgaris L.) that inhibits some insect and mammalian α-amylases. Several clinical studies support the beneficial use of bean αAI for control of diabetes and obesity. Commercial extracts of P. vulgaris are available but their efficacy is still under question, mainly because some of these extracts contain antinutritional impurities naturally present in bean seeds and also exhibit a lower specific activity αAI. The production of recombinant αAI allows to overcome these disadvantages and provides a platform for the large-scale production of pure and functional αAI protein for biotechnological and pharmaceutical applications. RESULTS: A synthetic gene encoding αAI from the common bean (Phaseolus vulgaris cv. Pinto) was codon-optimised for expression in yeasts (αAI-OPT) and cloned into the protein expression vectors pKLAC2 and pYES2. The yeasts Kluyveromyces lactis GG799 (and protease deficient derivatives such as YCT390) and Saccharomyces cerevisiae YPH499 were transformed with the optimised genes and transformants were screened for expression by antibody dot blot. Recombinant colonies of K. lactis YCT390 that expressed and secreted functional αAI into the culture supernatants were selected for further analyses. Recombinant αAI from K. lactis YCT390 was purified using anion-exchange and affinity resins leading to the recovery of a functional inhibitor. The identity of the purified αAI was confirmed by mass spectrometry. Recombinant clones of S. cerevisiae YPH499 expressed functional αAI intracellularly, but did not secrete the protein. CONCLUSIONS: This is the first report describing the heterologous expression of the α-amylase inhibitor 1 (αAI) from P. vulgaris in yeasts. We demonstrated that recombinant strains of K. lactis and S. cerevisiae expressed and processed the αAI precursor into mature and active protein and also showed that K. lactis secretes functional αAI.

Recombinant protein expression of Moringa oleifera lectin in methylotrophic yeast as active coagulant for sustainable high turbid water treatment.

The natural coagulant Moringa oleifera lectin (MoL) as cationic protein is a promising candidate in coagulation process of water treatment plant. Introducing the gene encoding MoL into a host, Pichia pastoris, to secrete soluble recombinant protein is assessed in this study. Initial screening using PCR confirmed the insertion of MoL gene, and SDS-PAGE analysis detected the MoL protein at 8 kDa. Cultured optimization showed the highest MoL protein at 520 mg/L was observed at 28 °C for 144 h of culturing by induction in 1% methanol. Approximately, 0.40 mg/mL of recombinant MoL protein showed 95 ± 2% turbidity removal of 1% kaolin suspension. In 0.1% kaolin suspension, the concentration of MoL at 10 µg/mL exhibits the highest turbidity reduction at 68 ± 1%. Thus, recombinant MoL protein from P. pastoris is an effective coagulant for water treatment.

Lectin I from Bauhinia variegata (BVL-I) expressed by Pichia pastoris inhibits initial adhesion of oral bacteria in vitro.

Lectins are non-immune proteins that reversibly bind to carbohydrates in a specific manner. Bauhinia variegata lectin I (BVL-I) is a Gal/GalNAc-specific, single-chain lectin isolated from Bauhinia variegata seeds that has been implicated in the inhibition of bacterial adhesion and the healing of damaged skin. Since the source of the native protein (nBVL) is limited, this study aimed to produce recombinant BVL-I in Pichia pastoris (rBVL-Ip). The coding sequence for BVL-I containing preferential codons for P. pastoris was cloned into the pPICZαB plasmid. A single expressing clone was selected and fermented, resulting in the secretion and glycosylation of the protein. Fed-batch fermentation in 7L-scale was performed, and the recombinant lectin was purified from culture supernatant, resulting in a yield of 1.5mg/L culture. Further, rBVL-Ip was compared to nBVL and its recombinant version expressed in Escherichia coli BL21 (DE3) (rBVL-Ie). Although it was expressed as a monomer, rBVL-Ip retained its biological activity since it was able to impair the initial adhesion of Streptococcus mutans and S. sanguinis in an in vitro model of biofilm formation and bacterial adhesion. In summary, rBVL-Ip produced in Pichia pastoris represents a viable alternative to large-scale production, encouraging further biological application studies with this lectin.

cDNA cloning, characterization, and pharmacologic evaluation of anticancer activity of a lectin gene in Pinellia integrifolia.

Plant lectins are proteins that possess at least one non-catalytic domain, which could reversibly bind to specific monosaccharides or oligosaccharides. The important roles played by plant lectins in immune regulation, signaling pathways, and plant defense could be attributed to their specific binding activities with carbohydrates. In this study, a Pinellia integrifolia lectin gene, designated pia, was cloned using rapid amplification of cDNA ends. The open reading frame (ORF) of pia was constructed into the pET-28a vector, and a 33-kDa recombinant protein was induced in Escherichia coli BL21. The hemagglutination and anticancer properties of the purified recombinant protein were assayed in vitro. The results indicated that the full-length cDNA of pia was 1210 bp long, containing an 807-bp ORF encoding a 268-amino acid peptide. The putative P. integrifolia lectin protein (PIA) contained three mannose-binding sites. The agglutinating activity exhibited by PIA was inhibited by D-mannose. PIA was also shown to exert an anti-proliferative activity against nasopharyngeal carcinoma, human cervical carcinoma, and human breast cancer cell lines in vitro. These results could be applied to determine the function of PIA in the future.

[Genes encoding hevein-like antimicrobial peptides WAMPs: Expression in response to phytohormones and environmental factors].

We investigated the role of genes of hevein-like antimicrobial peptides of the WAMP family in the protection of wheat plants against biotic and abiotic stress. The semiquantitative RT-PCR method was used to examine the expression of wamp genes in wheat seedlings in response to infection by pathogens and exposure to phytohormones and ions of a heavy metal ion­cadmium. We discovered that wheat germ contamination by harmful fungi significantly increases expression of genes of the wamp family, and the primary transcript is wamp-2. We determined that salicylic acid, rather than methyl jasmonate, induces expression of genes of the wamp family. We showed that abiotic stress induced by cadmium ions inhibits expression of wamp genes in the roots with no effect on their expression in shoots. The results support the protective role of wamp genes in the response of wheat plants to infections by pathogens. In turn, the resistance to abiotic stress induced by cadmium ions does not appear to be associated with expression of genes of the wamp family.

Lectin engineering, a molecular evolutionary approach to expanding the lectin utilities.

In the post genomic era, glycomics--the systematic study of all glycan structures of a given cell or organism--has emerged as an indispensable technology in various fields of biology and medicine. Lectins are regarded as "decipherers of glycans", being useful reagents for their structural analysis, and have been widely used in glycomic studies. However, the inconsistent activity and availability associated with the plant-derived lectins that comprise most of the commercially available lectins, and the limit in the range of glycan structures covered, have necessitated the development of innovative tools via engineering of lectins on existing scaffolds. This review will summarize the current state of the art of lectin engineering and highlight recent technological advances in this field. The key issues associated with the strategy of lectin engineering including selection of template lectin, construction of a mutagenesis library, and high-throughput screening methods are discussed.

Insecticidal activity of plant lectins and potential application in crop protection.

Lectins constitute a complex group of proteins found in different organisms. These proteins constitute an important field for research, as their structural diversity and affinity for several carbohydrates makes them suitable for numerous biological applications. This review addresses the classification and insecticidal activities of plant lectins, providing an overview of the applicability of these proteins in crop protection. The likely target sites in insect tissues, the mode of action of these proteins, as well as the use of lectins as biotechnological tools for pest control are also described. The use of initial bioassays employing artificial diets has led to the most recent advances in this field, such as plant breeding and the construction of fusion proteins, using lectins for targeting the delivery of toxins and to potentiate expected insecticide effects. Based on the data presented, we emphasize the contribution that plant lectins may make as tools for the development of integrated insect pest control strategies.

Datura stramonium agglutinin: cloning, molecular characterization and recombinant production in Arabidopsis thaliana.

Datura stramonium seeds contain at least three chitin-binding isolectins [termed Datura stramonium agglutinin (DSA)] as homo- or heterodimers of A and B subunits. We isolated a cDNA encoding isolectin B (DSA-B) from an immature fruit cDNA library; this contained an open reading frame encoding 279 deduced amino acids, which was confirmed by partial sequencing of the native DSA-B peptide. The sequence consisted of: (i) a cysteine (Cys)-rich carbohydrate-binding domain composed of four conserved chitin-binding domains and (ii) an extensin-like domain of 37 residues containing four SerPro4-6 motifs that was inserted between the second and third chitin-binding domains (CBDs). Although each chitin-binding domain contained eight conserved Cys residues, only the second chitin-binding domain contained an extra Cys residue, which may participate in dimerization through inter-disulfide bridge formation. Using matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry, the molecular mass of homodimeric lectin composed of two B-subunits was determined as 68,821 Da. The molecular mass of the S-pyridilethylated B-subunit were found to be 37,748 Da and that of the de-glycosylated form was 26,491 Da, which correlated with the molecular weight estimated from the deduced sequence. Transgenic Arabidopsis plants overexpressing the dsa-b demonstrated hemagglutinating activity. Recombinant DSA-B was produced as a homodimeric glycoprotein with a similar molecular mass to that of the native form. Moreover, the N-terminus of the purified recombinant DSA-B protein was identical to that of the native DSA-B, confirming that the cloned cDNA encoded DSA-B.

Conditional genetic transsynaptic tracing in the embryonic mouse brain.

Anatomical path tracing is of pivotal importance to decipher the relationship between brain and behavior. Unraveling the formation of neural circuits during embryonic maturation of the brain however is technically challenging because most transsynaptic tracing methods developed to date depend on stereotaxic tracer injection. To overcome this problem, we developed a binary genetic strategy for conditional genetic transsynaptic tracing in the mouse brain. Towards this end we generated two complementary knock-in mouse strains to selectively express the bidirectional transsynaptic tracer barley lectin (BL) and the retrograde transsynaptic tracer Tetanus Toxin fragment C from the ROSA26 locus after Cre-mediated recombination. Cell-specific tracer production in these mice is genetically encoded and does not depend on mechanical tracer injection. Therefore our experimental approach is suitable to study neural circuit formation in the embryonic murine brain. Furthermore, because tracer transfer across synapses depends on synaptic activity, these mouse strains can be used to analyze the communication between genetically defined neuronal populations during brain development at a single cell resolution. Here we provide a detailed protocol for transsynaptic tracing in mouse embryos using the novel recombinant ROSA26 alleles. We have utilized this experimental technique in order to delineate the neural circuitry underlying maturation of the reproductive axis in the developing female mouse brain.

Optimising expression of the recombinant fusion protein biopesticide ω-hexatoxin-Hv1a/GNA in Pichia pastoris: sequence modifications and a simple method for the generation of multi-copy strains.

Production of recombinant protein bio-insecticides on a commercial scale can only be cost effective if host strains with very high expression levels are available. A recombinant fusion protein containing an arthropod toxin, ω-hexatoxin-Hv1a, (from funnel web spider Hadronyche versuta) linked to snowdrop lectin (Galanthus nivalis agglutinin; GNA) is an effective oral insecticide and candidate biopesticide. However, the fusion protein was vulnerable to proteolysis during production in the yeast Pichia pastoris. To prevent proteolysis, the Hv1a/GNA fusion expression construct was modified by site-directed mutagenesis to remove a potential Kex2 cleavage site at the C-terminus of the Hv1a peptide. To obtain a high expressing clone of P. pastoris to produce recombinant Hv1a/GNA, a straightforward method was used to produce multi-copy expression plasmids, which does not require multiple integrations to give clones of P. pastoris containing high copy numbers of the introduced gene. Removal of the Kex2 site resulted in increased levels of intact fusion protein expressed in wild-type P. pastoris strains, improving levels of intact recombinant protein recoverable. Incorporation of a C-terminal (His)6 tag enabled single step purification of the fusion protein. These modifications did not affect the insecticidal activity of the recombinant toxin towards lepidopteran larvae. Introduction of multiple expression cassettes increased the amount of secreted recombinant fusion protein in a laboratory scale fermentation by almost tenfold on a per litre of culture basis. Simple modifications in the expression construct can be advantageous for the generation of high expressing P. pastoris strains for production of a recombinant protein, without altering its functional properties.

The identification of in vitro production of lectin from callus cultures of Korean mistletoe (Viscum album L. var. coloratum).

Despite potential medical, economical, and agronomical importance, the bioprocessing of mistletoe cell cultures, from callus cultures to mass production of high-value products (e.g., lectins and viscotoxins), has been unsuccessful to date. In this study, we confirmed the potential of in vitro lectin production from callus cultures of Korean mistletoe (Viscum album L. var. coloratum).

Pinellia ternata agglutinin produced in Bombyx mori cells exhibits bioactivity.

Pinellia ternata agglutinin (PTA) is highly homologous to many other monocot mannose-binding lectins which reportedly possess antitumor activities. Its production in silkworm cells has great application potential because the baculovirus expression system can produce post-translationally modified proteins at low cost. In the current study, the pta gene was cloned and expressed in silkworm cells, and the expressed protein was analyzed using a hemagglutination assay. A preliminary in vitro study on its anti-proliferative activity was performed. The results show that the recombinant PTA with an apparent molecular mass of 29 kDa can hemagglutinate rabbit erythrocytes and this activity can be inhibited by D-mannan at a low concentration. In addition, the recombinant hemagglutinin exhibited a dose-dependent anti-proliferative activity on hepatoma cells. The results of the current study suggest that PTA and other important bioactive proteins could be produced by silkworm bioreactor for biomedicine research and application.

The airway antigen sampling system: respiratory M cells as an alternative gateway for inhaled antigens.

In this study, we demonstrated a new airway Ag sampling site by analyzing tissue sections of the murine nasal passages. We revealed the presence of respiratory M cells, which had the ability to take up OVA and recombinant Salmonella typhimurium expressing GFP, in the turbinates covered with single-layer epithelium. These M cells were also capable of taking up respiratory pathogen group A Streptococcus after nasal challenge. Inhibitor of DNA binding/differentiation 2 (Id2)-deficient mice, which are deficient in lymphoid tissues, including nasopharynx-associated lymphoid tissue, had a similar frequency of M cell clusters in their nasal epithelia to that of their littermates, Id2(+/-) mice. The titers of Ag-specific Abs were as high in Id2(-/-) mice as in Id2(+/-) mice after nasal immunization with recombinant Salmonella-ToxC or group A Streptococcus, indicating that respiratory M cells were capable of sampling inhaled bacterial Ag to initiate an Ag-specific immune response. Taken together, these findings suggest that respiratory M cells act as a nasopharynx-associated lymphoid tissue-independent alternative gateway for Ag sampling and subsequent induction of Ag-specific immune responses in the upper respiratory tract.

Rapid activation of specific phospholipase(s) D by cytokinin in Amaranthus assay system.

The suggested link between intracellular cytokinin signaling and phospholipase D (PLD, EC 3.1.4.4.) activity (Romanov et al. 2000, 2002) was investigated. The activity of PLD in the early period of cytokinin action was studied in vivo in derooted Amaranthus caudatus seedlings, using the level of phosphatidylbutanol production as a measure of PLD activity. Rapid activation of phosphatidylbutanol synthesis was demonstrated as early as within 5 min of cytokinin administration. Neomycin, a known phosphatidylinositol-4,5-bisphosphate (PIP(2)) antagonist, strongly repressed both physiological cytokinin effect and cytokinin-dependent PLD activation. N-acylethanolamine (NAE 12), an inhibitor of alpha-class PLD, did not influence significantly cytokinin effect on Amaranthus seedlings. Together, results suggest the involvement of PIP(2)-dependent non-class alpha-PLD in the molecular mechanism of cytokinin action.

[Heterologous expression of a synthetic gene encoding a novel hevein-type antimicrobial peptide of Leymus arenarius in Escherichia coli cells].

A novel antifungal peptide, LAMP-Ia, was isolated from sand-elymus (Leymus arenarius) seeds. Expression of a synthetic gene encoding this peptide in Escherichia coli cells was obtained. The target peptide was expressed as a fusion with thioredoxin. Identity of the recombinant peptide to native LAMP-Ia was confirmed by chromatography, mass spectrometry, and amino acid sequencing. LAMP-Ia displayed a high inhibitory activity in respect of a number of phytopathogenic fungi in in vitro assays, which opens up possibilities for the gene encoding it to be used for genetic transformation of plants and for engineering pathogen-resistant crops.

RANKL is necessary and sufficient to initiate development of antigen-sampling M cells in the intestinal epithelium.

Microfold cells (M cells) are specialized epithelial cells situated over Peyer's patches (PP) and other organized mucosal lymphoid tissues that transport commensal bacteria and other particulate Ags into intraepithelial pockets accessed by APCs. The TNF superfamily member receptor activator of NF-kappaB ligand (RANKL) is selectively expressed by subepithelial stromal cells in PP domes. We found that RANKL null mice have <2% of wild-type levels of PP M cells and markedly diminished uptake of 200 nm diameter fluorescent beads. Ab-mediated neutralization of RANKL in adult wild-type mice also eliminated most PP M cells. The M cell deficit in RANKL null mice was corrected by systemic administration of exogenous RANKL. Treatment with RANKL also induced the differentiation of villous M cells on all small intestinal villi with the capacity for avid uptake of Salmonella and Yersinia organisms and fluorescent beads. The RANK receptor for RANKL is expressed by epithelial cells throughout the small intestine. We conclude that availability of RANKL is the critical factor controlling the differentiation of M cells from RANK-expressing intestinal epithelial precursor cells.