Development of a spotted sea bass (Lateolabrax maculatus) bulbus arteriosus cell line and its application to fish virology and immunology

The bulbus arteriosus tissue of teleosts, which is located at the forefront of the heart, is used to reduce the pulse pressure. In this study, we constructed a permanent cell line (LmAB) for the first time using bulbus arteriosus tissue from spotted sea bass (Lateolabrax maculatus). This cell line has been passaged more than 80 times. Currently, it can be subcultured in L-15 medium with 8 % fetal bovine serum added. The optimal fetal bovine serum concentration and culture temperature for LmAB cells at 62 passages are 20 % and 28 °C, respectively. This cell line consists predominantly of epithelial-like cells. We used 18S rRNA gene sequencing to confirm that LmAB cells originated from spotted sea bass. Karyotype analysis revealed that 43 % of LmAB cells in passage 63 had 48 chromosomes. Exogenous plasmid transfection revealed that LmAB cells can express the green fluorescent protein gene with a transfection efficiency of up to 40 %, indicating that these cells can be used for in vitro genetic research. LmAB cells showed susceptibility to nervous necrosis virus, largemouth bass ulcer syndrome virus, and infectious spleen and kidney necrosis virus, which results in severe cytopathic effects. PCR analysis verified that these viruses can replicate in LmAB cells, and analysis of cytoskeletal F-actin patterns verified that infected cells exhibit serious changes in their actin cytoskeleton. LmAB cells infected with these three viruses showed increased expressions of interferon signaling pathway genes (IFNd, IFNγ-rel, and ISG15), indicating that the host interferon signaling pathway participates in the antiviral immune response. These findings indicate that our newly developed LmAB cell line is a valuable resource for future research in genetics, virology, and immunology.

Actions of WNT family member 5A to regulate characteristics of development of the bovine preimplantation embryo†

WNT signaling is important for regulation of embryonic development. The most abundant WNT gene expressed in the bovine endometrium during the preimplantation period is WNT5A. One objective was to determine whether WNT5A regulates competence of the bovine preimplantation embryo to become a blastocyst and alters the number of cells in the inner cell mass and trophectoderm. A second objective was to delineate features of the cell-signaling mechanisms involved in WNT5A actions. WNT5A caused a concentration-dependent increase in the proportion of embryos developing to the blastocyst stage and in the number of inner cell mass cells in the resultant blastocysts. A concentration of 200 ng/mL was most effective, and a higher concentration of 400 ng/mL was not stimulatory. Bovine serum albumin in culture reduced the magnitude of effects of WNT5A on development to the blastocyst stage. WNT5A affected expression of 173 genes at the morula stage; all were upregulated by WNT5A. Many of the upregulated genes were associated with cell signaling. Actions of WNT5A on development to the blastocyst stage were suppressed by a Rho-associated coiled-coil kinase (ROCK) signaling inhibitor, suggesting that WNT5A acts through Ras homology gene family member A (RhoA)/ROCK signaling. Other experiments indicated that actions of WNT5A are independent of the canonical β-catenin signaling pathway and RAC1/c-Jun N-terminal kinase (JNK) signaling. This is the first report outlining the actions of WNT5A to alter the development of the mammalian embryo. These findings provide insights into how embryokines regulate maternal-embryonic communication.

Analysis of protein denaturation, aggregation and post-translational modification by agarose native gel electrophoresis

Agarose native gel electrophoresis has been developed to separate proteins and protein complexes in the native state. Here, we applied this technology to analyze proteins that undergo degradation, post-translational modification or chemical/physical changes. Antibodies showed aggregation/association upon acid or heat treatment. Limited reduction of disulfide bonds resulted in non-covalent aggregation of bovine serum albumin and cleavage of only inter-chain linkages of an antibody that had no effects on its overall structure. Native agarose gel analysis showed changes in mobility of human transferrin upon Fe³⁺ binding. Analysis of a commercial glycated human hemoglobin A1c showed no difference in electrophoretic pattern from un-modified hemoglobin. Native agarose gel showed aggregation of a virus upon acid or heat treatment. We have extracted bands of bovine serum albumin from the agarose native gel for sodium dodecylsulfate gel electrophoresis analysis, showing degradation of aged sample. Lastly, we analyzed phosphorylation of Zap70 kinase by native gel and Western blotting. These applications should expand the utility of this native gel electrophoresis technology.

Revisiting the conformational state of albumin conjugated to gold nanoclusters: A self-assembly pathway to giant superstructures unraveled

Bovine serum albumin (BSA) is often employed as a proteinaceous component for synthesis of luminescent protein-stabilized gold nanoclusters (AuNC): intriguing systems with many potential applications. Typically, the formation of BSA-AuNC conjugate occurs under strongly alkaline conditions. Due to the sheer complexity of intertwined chemical and structural transitions taking place upon BSA-AuNC formation, the state of albumin enveloping AuNCs remains poorly characterized. Here, we study the conformational properties of BSA bound to AuNCs using an array of biophysical tools including vibrational spectroscopy, circular dichroism, fluorescence spectroscopy and trypsin digestion. The alkaline conditions of BSA-AuNC self-assembly appear to be primary responsible for the profound irreversible disruption of tertiary contacts, partial unfolding of native α-helices, hydrolysis of disulfide bonds and the protein becoming vulnerable to trypsin digestion. Further unfolding of BSA-AuNC by guanidinium hydrochloride (GdnHCl) is fully reversible equally in terms of albumin's secondary structure and conjugate's luminescent properties. This suggests that binding to AuNCs traps the albumin molecule in a state that is both partly disordered and refractory to irreversible misfolding. Indeed, when BSA-AuNC is subjected to conditions favoring self-association of BSA into amyloid-like fibrils, the buildup of non-native β-sheet conformation is less pronounced than in a control experiment with unmodified BSA. Unexpectedly, BSA-AuNC reveals a tendency to self-assemble into giant twisted superstructures of micrometer lengths detectable with transmission electron microscopy (TEM), a property absent in unmodified BSA. The process is accompanied by ordering of bound AuNCs into elongated streaks and simultaneous decrease in fluorescence intensity. The newly discovered self-association pathway appears to be specifically accessible to protein molecules with a certain restriction on structural dynamics which in the case of BSA-AuNC arises from binding to metal nanoclusters. Our results have been discussed in the context of mechanisms of protein misfolding and applications of BSA-AuNC.

[PLANT GENETIC TRANSFORMATION USING CARBON NANOTUBES FOR DNA DELIVERY]

The possibility of exploiting carbon nanotubes (CNTs)-based nanocarriers to deliver genes into protoplasts, callus and mesophyll explants of plants was examined. Using single-walled CNTs (SWCNTs) at the concentration of 20 μg/ml and multi-walled CNTs (MWCNTs) at the concentration of 15 μg/ml genetic transformation of Nicotiana tabacum L. mesophyll protoplasts with plasmid pGreen 0029 was carried out and transient expression of reporter yfp gene in the protoplasts was observed. Using SWCNTs at the concentration of 40 μg/ml and MWCNTs at the concentration of 30 μg/ml genetic transformation of N. tabacum callus and leaf explants with nptII gene as a part of plasmid pGreen 0029 was carried out. As a result plant regeneration on selective medium containing 50 mg/lkanamycin was shown. SWCNTs-based nanocarriers de-onstrated their appli-ability to transform protoplasts as well as walled plant cells. Whereas, MWCNTs-based nano-arriers were suitable only for transformation of proto-lasts due to the limiting role of cellulose walls in cell penetration.

Extracellular matrix is modulated in advanced glycation end products milieu via a RAGE receptor dependent pathway boosted by transforming growth factor-β1 RAGE

BACKGROUND

Interstitial fibrosis is induced by imbalances in extracellular matrix homeostasis. Advanced glycation end products (AGEs) can bind and activate the receptor for AGEs (RAGE), which is involved in diabetic nephropathy. We set out to identify the role of AGEs in producing alterations leading to matrix hypertrophy and the pathway through which aminoguanidine, as well as anti-RAGE and anti-transforming growth factor (TGF)-β1 antibody treatments could prevent these modifications.

METHODS

Human embryonic kidney (HEK-293) cells were exposed to glycated bovine serum albumin (AGE-BSA) and co-treated with neutralizing antibodies or aminoguanidine. The effects on the transcriptional and translational levels of RAGE, TGF-β1 and collagen IV were evaluated, while metalloproteinase activity was assessed by gelatin zymography.

RESULTS

AGE-BSA (200 μg/mL) upregulated RAGE's expression, while TGF-β1 synthesis and the formation of its bioactive form were increased in a dose-dependent manner by AGEs. AGE-BSA exposure increased both matrix metalloproteinase (MMP) activity and collagen IV synthesis, boosted by TGF-β1 upregulation. Aminoguanidine's effects revealed that small concentrations (10 μmol/L) enhance AGE-BSA effects, by increasing the expression of RAGE and TGF-β1, while higher concentrations (100 μmol/L) contribute to their downregulation.

CONCLUSIONS

Although AGEs regulate RAGE and TGF-β1 by distinct pathways, RAGE activation leads to a further increase of TGF-β1 levels. MMP-2 activity seems to rely on TGF-β1, while MMP-9 was dependent on RAGE. These factors converge to control collagen IV turnover. Furthermore, although the antibody treatments might appear more efficient than AG in decreasing collagen IV levels, the cells compensate the RAGE and TGF-β1 blockade by increasing the mRNA expression of these proteins.

Intracellular protein delivery and gene transfection by electroporation using a microneedle electrode array

The impact of many biopharmaceuticals, including protein- and gene-based therapies, has been limited by the need for better methods of delivery into cells within tissues. Here, intracellular delivery of molecules and transfection with plasmid DNA by electroporation is presented using a novel microneedle electrode array designed for the targeted treatment of skin and other tissue surfaces. The microneedle array is molded out of polylactic acid. Electrodes and circuitry required for electroporation are applied to the microneedle array surface by a new metal-transfer micromolding method. The microneedle array maintains mechanical integrity after insertion into pig cadaver skin and is able to electroporate human prostate cancer cells in vitro. Quantitative measurements show that increasing electroporation pulse voltage increases uptake efficiency of calcein and bovine serum albumin, whereas increasing pulse length has lesser effects over the range studied. Uptake of molecules by up to 50% of cells and transfection of 12% of cells with a gene for green fluorescent protein is demonstrated at high cell viability. It is concluded that the microneedle electrode array is able to electroporate cells, resulting in intracellular uptake of molecules, and has potential applications to improve intracellular delivery of proteins, DNA, and other biopharmaceuticals.

Structural and immunogenic effects of multiple hapten loading on carrier protein

Haptens are low-molecular-weight compounds that are usually nonimmunogenic in nature. These compounds are, in general, conjugated with carrier proteins to elicit an immune response for antibody production. In this work, we report the effect of multiple hapten loading on carrier protein after conjugation by monitoring the structural and immunogenic properties of the protein. Biochemical conjugation of carboxylated hapten (atrazine derivative) to bovine serum albumin via epsilon-amino groups of lysine residues was monitored by the intrinsic fluorescence intensity of tryptophan residues of protein. A significant blue shift of emission maxima confirmed the conformational changes with increasing molar ratio of hapten:protein. Circular dichroism spectroscopy suggested a decreasing trend for alpha-helical and increased formation of beta-sheet structures in hapten-loaded protein. A further insight was sought by using molecular modeling methods for understanding of structural changes in the native protein post-hapten conjugation. A sequential approach for hapten loading on the carrier confirmed that initial binding could affect the possible binding sites for subsequent incorporation of hapten molecules. These changes play a major role in the immunogenic response of hapten-carrier conjugate. The approach taken to develop this model is promising, and can be generalized for studies with other protein-hapten combinations.

The use of genetic relationships among cattle breeds in the formulation of rational breeding policies: a re-examination of the example of the South Devon and the Gelbvieh

It has been claimed that the origin of the South Devon breed of cattle is 'unknown' and that biochemical polymorphisms '. . . indicate that Gelbvieh and South Devon had a common ancestry on the Continent and are distinct from other British breeds such as Hereford, Angus and Jersey' (Kidd et al., 1974). In fact, historical records indicate that the South Devon evolved largely from native Devon cattle and is a close relative of other English Lowland breeds such as the North Devon and Hereford. Information about crosses from other breeds makes no mention of the Gelbvieh but emphasises the contribution of Channel Island breeds, especially the Guernsey. Data for biochemical polymorphisms in the relevant breeds show agreement with the historical information and with the biogeography of the breeds involved.

Polymorphic plasma postalbumin (Po) of llamas and alpacas identified as Gc protein

Immunoblotting with antiserum specific to human Gc protein was used to identify Gc protein as the previously reported polymorphic plasma postalbumin (Po) of llamas and alpacas. This is the first report of Gc polymorphism in camelid species. One Gc variant appeared to be identical in llamas, alpacas, dromedaries and bactrian camels.

Horizontal polyacrylamide gradient gel electrophoresis for the simultaneous phenotyping of transferrin, post-transferrin, albumin and post-albumin in the blood plasma of cattle

A simple method of horizontal polyacrylamide gel electrophoresis was described for the simultaneous phenotyping of transferrin, post-transferrin, albumin and post-albumin in the blood plasma of cattle. A step gradient gel of 8, 4, 12 and 14% acrylamide concentration was used. The method enabled the detection of a new protein polymorphism in the post-transferrin region. Two alleles were observed. The transferrin phenotypes involving D1 and D2 alleles were clearly separated. The resolution of the post-albumin fractions was also better than described by earlier methods.

Chemical classification of cattle. 1. Breed groups

From approximately 1000 papers with data on protein polymorphism in some 216 breeds of cattle, 10 polymorphic proteins were compared in means and variances of gene frequencies (arcsin p 1/2) for ten well-recognized breed groups for 196 of the breeds. The polymorphic proteins were alpha-lactalbumin, beta-lactoglobulin, caseins (alpha s1, beta and chi), serum albumin, transferrin, haemoglobin, amylase I and carbonic anhydrase II. The breed groups were North European, Pied Lowland, European Red brachyceros, Channel Island brachyceros, Upland brachyceros, primigenius-brachyceros mixed, primigenius, Indian Zebu, African Humped (with Zebu admixture), and African Humped (Sanga). The coherence within groups and the differences between groups are often impressive. Only carbonic anhydrase II fails to differentiate at least some of the major breed groups. In some cases paradoxical distributions of rare genetic variants can be explained by a more detailed inspection of breed history. The chemical data support the morphological and geographical divisions of cattle into major breed groups. There are three distinct but related brachyceros groups; for some polymorphisms the two Channel Island breeds, the Jersey and the Guernsey, are quite divergent. Although some authorities have considered the Pied Lowland as primigenius, it is a very distinct breed group.

Characterization of bovine serum albumin glycated with glucose, galactose and lactose

The non-enzymatic reaction between reducing sugars and proteins, known as glycation, has received increased attention from nutritional and medical research. In addition, there is a large interest in obtaining glycoconjugates of pure well-characterized oligosaccharides for biological research. In this study, glycation of bovine serum albumin (BSA) by d-glucose, d-galactose and d-lactose under dry-heat at 60 degrees C for 30, 60, 120, 180 or 240 min was assessed and the glycated products studied in order to establish their biological recognition by lectins. BSA glycation was monitored using gel electrophoresis, determination of available amino groups and lectin binding assays. The BSA molecular mass increase and glycation sites were investigated by mass spectrometry and through digestion with trypsin and chymotrypsin. Depending on time and type of sugar, differences in BSA conjugation were achieved. Modified BSA revealed reduction of amino groups' availability and slower migration through SDS/PAGE. d-galactose was more reactive than d-glucose or d-lactose, leading to the coupling of 10, 3 and 1 sugar residues, respectively, after 120 minutes of reaction. BSA lysines (K) were the preferred modified amino acids; both K256 and K420 appeared the most available for conjugation. Only BSA-lactose showed biological recognition by specific lectins.

Formation of an adduct by clenbuterol, a beta-adrenoceptor agonist drug, and serum albumin in human saliva at the acidic pH of the stomach: evidence for an aryl radical-based process

Clenbuterol (CLB) is an antiasthmatic drug used also illegally as a lean muscle mass enhancer in both humans and animals. CLB and amine-related drugs in general are nitrosatable, thus raising concerns regarding possible genotoxic/carcinogenic activity. Oral administration of CLB raises the issue of its possible transformation by salivary nitrite at the acidic pH of gastric juice. In acidic human saliva CLB was rapidly transformed to the CLB arenediazonium ion. This suggests a reaction of CLB with salivary nitrite, as confirmed in aerobic HNO(2) solution by a drastic decrease in nitric oxide, nitrite, and nitrate. In human saliva, both glutathione and ascorbic acid were able to inhibit CLB arenediazonium formation and to react with preformed CLB arenediazonium. The effect of ascorbic acid is particularly pertinent because this vitamin is actively concentrated within the gastric juice. EPR spin trapping experiments showed that preformed CLB arenediazonium ion was reduced to the aryl radical by ascorbic acid, glutathione, and serum albumin, the major protein of saliva. As demonstrated by anti-CLB antibodies and MS, the CLB-albumin interaction leads to the formation of a covalent drug-protein adduct, with a preference for Tyr-rich regions. This study highlights the possible hazards associated with the use/abuse of this drug.

Collision-induced dissociative chemical cross-linking reagents and methodology: Applications to protein structural characterization using tandem mass spectrometry analysis

Chemical cross-linking combined with mass spectrometry is a viable approach to study the low-resolution structure of protein and protein complexes. However, unambiguous identification of the residues involved in a cross-link remains analytically challenging. To enable a more effective analysis across various MS platforms, we have developed a novel set of collision-induced dissociative cross-linking reagents and methodology for chemical cross-linking experiments using tandem mass spectrometry (CID-CXL-MS/MS). These reagents incorporate a single gas-phase cleavable bond within their linker region that can be selectively fragmented within the in-source region of the mass spectrometer, enabling independent MS/MS analysis for each peptide. Initial design concepts were characterized using a synthesized cross-linked peptide complex. Following verification and subsequent optimization of cross-linked peptide complex dissociation, our reagents were applied to homodimeric glutathione S-transferase and monomeric bovine serum albumin. Cross-linked residues identified by our CID-CXL-MS/MS method were in agreement with published crystal structures and previous cross-linking studies using conventional approaches. Common LC/MS/MS acquisition approaches such as data-dependent acquisition experiments using ion trap mass spectrometers and product ion spectral analysis using SEQUEST were shown to be compatible with our CID-CXL-MS/MS reagents, obviating the requirement for high resolution and high mass accuracy measurements to identify both intra- and interpeptide cross-links.

High sequence coverage by in-capillary proteolysis of native proteins and simultaneous analysis of the resulting peptides by nanoelectrospray ionization-mass spectrometry and tandem mass spectrometry

Losses of proteolytic peptides during extraction and/or purification procedures succeeding in-gel or in-solution digests of proteins frequently occur in the course of protein identification investigations. In order to overcome this disadvantage, the method of in-capillary digest was developed: native proteins were incubated in the presence of endoproteases in the electrospray capillary and the resulting peptides were analyzed by nanoelectrospray-mass spectrometry during the ongoing proteolysis. In-capillary digest of apomyglobin by use of trypsin in a molar ratio of 25:1 yielded complete degradation already after 15 min. The sequence coverage based on formation of molecular ions was 100% and peptide ions could be fragmented by collision-induced dissociation and sequenced. When myoglobin was incubated in the electrospray capillary with trypsin in a molar ratio of 500:1, a clear shift from molecular ions and miscleaved peptide ions to the expected final tryptic peptide ions was observed over a 2 h period. The peptide spectra obtained from tryptic in-capillary proteolysis of bovine serum albumin and apotransferrin, respectively, gave rise to sequence coverages of more than 40% for both proteins. The data obtained from the peptide maps as well as from collision-induced dissociation (CID) of selected peptides were more than sufficient for protein identification by database searches. An elephant milk protein preparation was used to demonstrate the application of in-capillary proteolysis on protein mixtures. Tryptic digest, simultaneous analysis of the proteolytic peptides by use of CID, and subsequent sequencing allowed the identification of lactoferrin, alphas1-casein, beta-casein, delta-casein, and kappa-casein by homology search.

Ultrasensitive proteomics using high-efficiency on-line micro-SPE-nanoLC-nanoESI MS and MS/MS

Ultrasensitive nanoscale proteomics approaches for characterizing proteins from complex proteomic samples of <50 ng of total mass are described. Protein identifications from 0.5 pg of whole proteome extracts were enabled by ultrahigh sensitivity (<75 zmol for individual proteins) achieved using high-efficiency (peak capacities of approximately 10(3)) 15-microm-i.d. capillary liquid chromatography separations (i.e., using nanoLC, approximately 20 nL/min mobile-phase flow rate at the optimal linear velocity of approximately 0.2 cm/s) coupled on-line with a micro-solid-phase sample extraction and a nanoscale electrospray ionization interface to a 11.4-T Fourier transform ion cyclotron resonance (FTICR) mass spectrometer (MS). Proteome measurement coverage improved as sample size was increased from as little as 0.5 pg of sample. It was found that a 2.5-ng sample provided 14% coverage of all annotated open reading frames for the microorganism Deinococcus radiodurans, consistent with previous results for a specific culture condition. The estimated detection dynamic range for detected proteins was 10(5)-10(6). An improved accurate mass and LC elution time two-dimensional data analysis methodology, used to both speed and increase the confidence of peptide/protein identifications, enabled identification of 872 proteins/run from a single 3-h nanoLC/FTICR MS analysis. The low-zeptomole-level sensitivity provides a basis for extending proteomics studies to smaller cell populations and potentially to a single mammalian cell. Application with ion trap MS/MS instrumentation allowed protein identification from 50 pg (total mass) of proteomic samples (i.e., approximately 100 times larger than FTICR MS), corresponding to a sensitivity of approximately 7 amol for individual proteins. Compared with single-stage FTICR measurements, ion trap MS/MS provided a much lower proteome measurement coverage and dynamic range for a given analysis time and sample quantity.

Hypoallergenic and T cell reactive analogue peptides of bovine serum albumin, the major beef allergen

We recently identified IgE-binding epitopes of bovine serum albumin (BSA), the major beef allergen, and found that the major epitope structure contains an EXXV motif. Here we report hypoallergenic analogue peptides of BSA that preserve T cell reactivity to retain the capacity to induce immunotolerance. Substitution of the glutamic acid in the EXXV sequence to aspartic acid leads to a remarkable reduction of IgE-binding ability and induces potent T cell proliferation. Moreover, in response to the substitutions, the production of INF-gamma is markedly increased compared with that elicited by the native peptides. Therefore, these analogue peptides represent potential candidates for specific immunotherapy.

Characterization of protein variants and post-translational modifications: ESI-MSn analyses of intact proteins eluted from polyacrylamide gels

We have developed a strategy to characterize protein isoforms, resulting from single-point mutations and post-translational modifications. This strategy is based on polyacrylamide gel electrophoresis separation of protein isoforms, mass spectrometry (MS) and MSn analyses of intact proteins, and tandem MS analyses of proteolytic peptides. We extracted protein isoforms from polyacrylamide gels by passive elution using SDS, followed by nanoscale hydrophilic phase chromatography for SDS removal. We performed electrospray ionization MS analyses of the intact proteins to determine their molecular mass, allowing us to draw hypotheses on the nature of the modification. In the case of labile post-translational modifications, like phosphorylations and glycosylations, we conducted electrospray ionization MSn analyses of the intact proteins to confirm their presence. Finally, after digestion of the proteins in solution, we performed tandem MS analyses of the modified peptides to locate the modifications. Using this strategy, we have determined the molecular mass of 5-10 pmol of a protein up to circa 50 kDa loaded on a gel with a 0.01% mass accuracy. The efficiency of this approach for the characterization of protein variants and post-translational modifications is illustrated with the study of a mixture of kappa-casein isoforms, for which we were able to identify the two major variants and their phosphorylation site and glycosylation motif. We believe that this strategy, which combines two-dimensional gel electrophoresis and mass spectrometric analyses of gel-eluted intact proteins using a benchtop ion trap mass spectrometer, represents a promising approach in proteomics.

Differential effects between amphoterin and advanced glycation end products on colon cancer cells

Amphoterin is 1 ligand of the receptor for advanced glycation end products (RAGE). We studied expression of amphoterin and RAGE mRNA and proteins in colorectal carcinoma cells and investigated their associations with the invasive activities of cells exposed to advanced glycation end products (AGE). Expression of RAGE and amphoterin was examined in 4 colorectal carcinoma cell lines. All cell lines expressed both RAGE and amphoterin. The effects of RAGE and amphoterin on cell growth (MTT assay), migration (wound healing assay) and invasion (in vitro invasion assay) were tested by treatment of cells with RAGE and amphoterin antisense S-oligodeoxynucleotides (ODNs). Cell growth, migration and invasion were inhibited significantly in Colo320 and WiDr carcinoma cells treated with RAGE and amphoterin antisense S-ODNs compared with sense-treated cells. Differences in ligand activity between amphoterin and AGE were examined with AGE-bovine serum albumin (BSA). AGE-BSA decreased cell growth, migration and invasion of amphoterin antisense S-ODN-treated Colo320 and WiDr cells compared with those of cells treated with Colo320 conditioned medium. Phosphorylation of extracellular signal-regulated kinase-1/2, Rac1 and AKT and production of matrix metalloproteinase 9 were increased to a greater degree by amphoterin than by AGE-BSA. In contrast, production of inducible nitric oxide synthase and nuclear factor-kappaBp65 were increased to a greater degree by AGE-BSA than by amphoterin.

Purification of plasmid DNA by an integrated operation comprising tangential flow filtration and nitrocellulose adsorption

There is an increasing interest in the development of scaleable and reproducible plasmid DNA purification protocols for vaccine and gene therapy. The use of an integrated unit operation, comprising tangential flow microfiltration coupled with the adsorption of contaminants onto nitrocellulose membranes as a single processing step was examined in this work. Experiments were performed using a custom-built tangential flow microfiltration rig (membrane area=12.5 cm(2)). Tangential flow filtration-adsorption of E. coli lysates containing a plasmid product removed most solids (>75%) and decreased chromosomal DNA contamination by 75% w/w. Total plasmid DNA concentration and supercoiled content of the permeate were virtually identical to those of the feed, indicating a recovery yield of 100% (transmission equal to 1). Results were similar for E. coli lysates containing either a 6.9 kb or a 20 kb plasmid. Significant reductions in RNA, endotoxin, and protein levels were also observed. The reproducibility and potential for scale up of this integrated filtration-adsorption operation makes it at attractive option for intermediate- to large-scale pharmaceutical-grade plasmid processing.

Evaluation of potential implication of membrane estrogen binding sites on ERE-dependent transcriptional activity and intracellular estrogen receptor-alpha regulation in MCF-7 breast cancer cells

The potential involvement of membrane estrogen binding sites in the induction of ERE-dependent transcriptional activity as well as in the regulation of intracellular estrogen receptor alpha (ER-alpha) level under estradiol (E2) stimulation was investigated. Our approach relied upon the use of two DCC-treated E2-BSA (bovine serum albumin) solutions (E2-6-BSA and E2-17-BSA). The absence of detectable free E2 in these solutions was established. Both E2-BSA conjugates led to a transient dose-dependent stimulation of the expression of ERE-luciferase (LUC) reporter gene in MVLN cells (MCF-7 cells stably transfected with a pVit-tk-LUC reporter plasmid), a property not recorded with free E2, which maintained enhanced transcriptional activity during the whole experiment. A very low concentration of E2 (10 pM) synergistically acted with E2-BSA conjugates. Hence, ERE-dependent transcriptional activity induced by these conjugates appeared to result from their known interactions with membrane estrogen binding sites. Anti-estrogens (AEs: 4-OH-TAM and RU 58,668), which antagonize genomic ER responses, abrogated the luciferase activity induced by E2-BSA conjugates, confirming a potential relationship between membrane-related signals and intracellular ER. Moreover, induction of luciferase was recorded when the cells were exposed to IBMX (3-isobutyl-1-methylxanthine) and cyclic nucleotides (cAMP/cGMP), suggesting the implication of the latter in the signal transduction pathway leading to the expression of the reporter gene. Growth factors (IGF-I, EGF and TGF-alpha) also slightly stimulated luciferase and synergistically acted with 10 pM E2, or 1 microM E2-BSA conjugates, in agreement with the concept of a cross-talk between steroids and peptides acting on the cell membrane. Remarkably, E2-BSA conjugates, IBMX and all investigated growth factors failed to down-regulate intracellular ER in MCF-7 cells, indicating the need for a direct intracellular interaction of the ligand with the receptor to regulate its level. ER elimination was, however, found in the presence of conditioned media (CMs) prepared from cells pre-exposed to E2-BSA conjugates, suggesting that they may produce (a) modulator(s) that may enhance receptor down-regulation when released within the medium.

Adenovirus hexon protein enhances nuclear delivery and increases transgene expression of polyethylenimine/plasmid DNA vectors

Inefficient nuclear delivery restricts transgene expression using polyelectrolyte DNA vectors. To increase transfer from the cytoplasm to the nucleus, we have covalently linked adenovirus hexon protein to polyethylenimine (PEI, 800 kDa). Activity of the conjugate was compared with PEI and PEI linked to albumin. Hexon-containing complexes gave 10-fold greater transgene expression in HepG2 cells than PEI/DNA or complexes containing albumin, without increasing cell uptake. Following cytoplasmic injection into Xenopus laevis oocytes, hexon-containing complexes showed reporter gene expression to be elevated by 10-fold compared with PEI/DNA. The ability of hexon to promote nuclear delivery of PEI/DNA nanoparticles was compared with that of classical nuclear localization sequences (NLS) by measuring transgene expression following intracytoplasmic microinjection of hexon-PEI/DNA complexes and NLS-albumin-PEI/DNA complexes in rat-1 fibroblasts. The resulting nuclear transfer efficiency was in the following order: hexon-PEI/DNA>NLS-albumin-PEI/DNA>PEI/DNA>DNA alone>albumin-PEI/DNA. The activities of both NLS-albumin-PEI and hexon-PEI were abolished by co-injection of wheat germ agglutinin, suggesting that both act by means of the nuclear pore complex (NPC); in contrast, excess free NLS-albumin abolished transgene expression with NLS-albumin-PEI/DNA, but only partially inhibited hexon-PEI/DNA. Nuclear transfer efficiency following cytoplasmic injection was dependent on DNA concentration for all materials, although hexon conjugates showed much better activity than NLS-albumin at low DNA doses (500-1000 plasmids/cell). Our data are consistent with hexon mediating nuclear delivery of plasmid complexes by means of the NPC, using mechanisms that are only partially dependent on the classical NLS import pathway. The hexon-mediated mechanism of nuclear import enables substantially better transgene expression, particularly when DNA concentrations in the cytoplasm are limiting.

The nucleoporin Nup153 is required for nuclear pore basket formation, nuclear pore complex anchoring and import of a subset of nuclear proteins

The nuclear pore complex (NPC) is a large proteinaceous structure through which bidirectional transport of macromolecules across the nuclear envelope (NE) takes place. Nup153 is a peripheral NPC component that has been implicated in protein and RNP transport and in the interaction of NPCs with the nuclear lamina. Here, Nup153 is localized by immunogold electron microscopy to a position on the nuclear ring of the NPC. Nuclear reconstitution is used to investigate the role of Nup153 in nucleo- cytoplasmic transport and NPC architecture. NPCs assembled in the absence of Nup153 lacked several nuclear basket components, were unevenly distributed in the NE and, unlike wild-type NPCs, were mobile within the NE. Importin alpha/beta-mediated protein import into the nucleus was strongly reduced in the absence of Nup153, while transportin-mediated import was unaffected. This was due to a reduction in import complex translocation rather than to defective receptor recycling. Our results therefore reveal functions for Nup153 in NPC assembly, in anchoring NPCs within the NE and in mediating specific nuclear import events.

Cyborg lectins: novel leguminous lectins with unique specificities

Bauhinia purpurea lectin (BPA) is one of the beta-galactose-binding leguminous lectins. Leguminous lectins contain a long metal-binding loop, part of which determines their carbohydrate-binding specificities. Random mutations were introduced into a portion of the cDNA coding BPA that corresponds to the carbohydrate-binding loop of the lectin. An library of the mutant lectin expressed on the surface of lambda foo phages was screened by the panning method. Several phage clones with an affinity for mannose or N-acetylglucosamine were isolated. These results indicate the possibility of making artificial lectins (so-called "cyborg lectins") with distinct and desired carbohydrate-binding specificities.

Identification of a nuclear transport inhibitory signal (NTIS) in the basic domain of HIV-1 Vif protein

The HIV-1 auxiliary protein Vif contains a basic domain within its sequence. This basic region,90RKKR93, is similar to the prototypic nuclear localization signal (NLS). However, Vif is not a nuclear protein and does not function in the nucleus. Here we have studied the karyophilic properties of this basic region. We have synthesized peptides corresponding to this positively charged NLS-like region and observed that these peptides inhibited nuclear transport via the importin pathway in vitro with IC50values in the micromolar range. Inhibition was observed only with peptides derived from the positively charged region, but not from other regions of the Vif protein, showing sequence specificity. On the other hand, the Vif inhibitory peptide Vif88-98 did not confer karyophilic properties when conjugated to BSA. The inactive Vif conjugate and the active SV40-NLS-BSA conjugate both contained a similar number of peptides conjugated to each BSA molecule, as was determined by amino acid analysis of the peptide-BSA conjugates. Thus, the lack of nuclear import of the Vif peptide-BSA conjugate cannot be attributed to insufficient number of conjugated peptide molecules per BSA molecule. Our results suggest that the HIV-1 Vif protein carries an NLS-like sequence that inhibits, but does not mediate, nuclear import via the importin pathway. We have termed such signals as nuclear transport inhibitory signals (NTIS). The possible role of NTIS in controlling nuclear uptake, and specifically during virus infection, is discussed herein. Our results raise the possibility that NLS-like sequences of certain low molecular weight viral proteins may serve as regulators of nucleocytoplasmic trafficking and not neccessarily as mediators of nuclear import.

Use of the KlADH4 promoter for ethanol-dependent production of recombinant human serum albumin in Kluyveromyces lactis

KlADH4 is a gene of Kluyveromyces lactis encoding a mitochondrial alcohol dehydrogenase activity which is specifically induced by ethanol. The promoter of this gene was used for the expression of heterologous proteins in K. lactis, a very promising organism which can be used as an alternative host to Saccharomyces cerevisiae due to its good secretory properties. In this paper we report the ethanol-driven expression in K. lactis of the bacterial beta-glucuronidase and of the human serum albumin (HSA) genes under the control of the KlADH4 promoter. In particular, we studied the extracellular production of recombinant HSA (rHSA) with integrative and replicative vectors and obtained a significant increase in the amount of the protein with multicopy vectors, showing that no limitation of KlADH4 trans-acting factors occurred in the cells. By deletion analysis of the promoter, we identified an element (UASE) which is sufficient for the induction of KlADH4 by ethanol and, when inserted in the respective promoters, allows ethanol-dependent activation of other yeast genes, such as PGK and LAC4. We also analyzed the effect of medium composition on cell growth and protein secretion. A clear improvement in the production of the recombinant protein was achieved by shifting from batch cultures (0.3 g/liter) to fed-batch cultures (1 g/liter) with ethanol as the preferred carbon source.

Superclustering of B cell receptor and Fc gamma RIIB1 activates Src homology 2-containing protein tyrosine phosphatase-1

Fc gamma RIIB1 (CD32) is a receptor that binds the Fc domain of Ag-complexed IgG. Coaggregation of B cell receptor (BCR) and Fc gamma RIIB1 generates a dominant negative signal that inhibits B cell activation. In Ag-specific Id-positive B cells, the co-cross-linking of BCR and Fc gamma RIIB1 by anti-Id Ab resulted in the association of both Src homology 2-containing protein tyrosine phosphatase (SHP-1) and Src homology 2-containing inositol phosphatase (SHIP) with the Fc gamma RIIB1; however, only SHIP activity was detected. "Superclustering" of the BCR and Fc gamma RIIB1 complex induced by stimulation with anti-Id Ab plus polyvalent Ag synergistically activated SHP-1. The degree of co-cross-linking between BCR and Fc gamma RIIB1 may determine the activation status of SHP-1 and SHIP.

Constitutively active protein phosphatase 1alpha causes Rb-dependent G1 arrest in human cancer cells

BACKGROUND

The retinoblastoma protein (Rb) needs to be phosphorylated by cyclin-dependent kinases (CDKs) before mammalian cells can enter the S phase of the cell cycle. As protein phosphatase 1 (PP1) activates Rb and is itself a target for inhibitory phosphorylation by CDKs in vitro, we asked whether any effects of PP1 on cell cycle progression depend on its phosphorylation and are mediated through Rb.

RESULTS

Using electrotransfer of recombinant protein into Rb-positive and Rb-negative cells, we have compared the effects of a wild-type PP1 catalytic subunit, PP1alpha, and a constitutively active mutant of this subunit (PP1alphaT320A) on G1 progression, proliferation rates, and cell viability. In treated cells, PP1alpha levels were elevated 6-16-fold and remained stable for at least 48 hours. In Rb-positive cells, PP1alphaT320A, but not PP1alpha, caused cell cycle arrest in late G1, which was associated with a lack of Rb phosphorylation. In Rb-negative cells, neither wild-type nor mutant phosphatase caused any change in cell cycle progression. Increased cell death was observed in both Rb-positive and Rb-negative cells, however, upon introduction of excess PP1alpha.

CONCLUSIONS

The difference between the effects of wild-type and mutant forms of PP1alpha suggests that PP1alpha has the potential to arrest cell growth in G1 unless it is inactivated by periodic phosphorylation at Thr320, presumably by CDKs that regulate passage through the G1-S cell cycle transition. Together, the effects in both cell types suggest that PP1alpha requires functional Rb to induce growth arrest, and that possibly another pool of PP1alpha induces cell death. This identifies PP1 as a potential target for therapeutic anti-proliferative strategies.

Development of an expert system for amino acid sequence identification

An expert system for amino acid sequence identification has been developed. The algorithm uses heuristic rules developed by human experts in protein sequencing. The system is applied to the chromatographic data of phenylthiohydantoin-amino acids acquired from an automated sequencer. The peak intensities in the current cycle are compared with those in the previous cycle, while the calibration and succeeding cycles are used as ancillary identification criteria when necessary. The retention time for each chromatographic peak in each cycle is corrected by the corresponding peak in the calibration cycle at the same run. The main improvement of our system compared with the onboard software used by the Applied Biosystems 477A Protein/Peptide Sequencer is that each peak in each cycle is assigned an identification name according to the corrected retention time to be used for the comparison with different cycles. The system was developed from analyses of ribonuclease A and evaluated by runs of four other protein samples that were not used in rule development. This paper demonstrates that rules developed by human experts can be automatically applied to sequence assignment. The expert system performed more accurately than the onboard software of the protein sequencer, in that the misidentification rates for the expert system were around 7%, whereas those for the onboard software were between 13 and 21%.

Cloning of human and rat p69 cDNA, a candidate autoimmune target in type 1 diabetes

Triggering of autoimmunity in insulin-dependent diabetes was linked to dietary bovine serum albumin (BSA). Anti-BSA antibodies from diabetes-prone rats precipitate a protein, p69, from islet cell lysates. We have used these antibodies to identify rat p69 cDNAs. Human p69 cDNA was identified by crosshybridization. The p69 coding regions show 87% nucleotide and 89% amino acid homology. Recombinant p69 is recognized by autoantibody and T cells from diabetic children.

Isolation and functional analysis of the promoter of the bovine serum albumin gene

The bovine serum albumin (bSA) promoter has been cloned from bovine genomic DNA using the polymerase chain reaction. In common with other albumin promoters, this promoter functions efficiently in the differentiated rat hepatoma cell line H4II and not in the its dedifferentiated derivative, H5. Analysis of 5' deletions of the bSA promoter after transient transfection into H4II has revealed that a short construct containing the HNF1 binding site and TATA box functions efficiently but requires the presence of the more upstream sequences to achieve full activity Footprint analysis of the promoter reveals seven sites of DNA protein interaction extending from -31 to -213. One of these sites, extending from -170 to -236, whose deletion results in a four fold increase in promoter activity. This site has not previously been reported in other albumin promoters and is bound by the C/EBP-like family of proteins.

Genetic studies of water buffalo blood markers. I. Red cell acid phosphatase, albumin, catalase, red cell alpha-esterase-3, group-specific component, and protease inhibitor

We have developed the methodologies for typing and family studies to establish the modes of inheritance of water buffalo red cell acid phosphatase (Acp), protease inhibitor (Pi), and group-specific component (Gc) on isoelectric focusing and albumin (Alb), red cell alpha-esterase-3 (Est-3), and catalase (Cat) on polyacrylamide gel electrophoresis. Family studies showed that Pi, Gc, Alb, and Cat are coded by autosomal genes with two codominant alleles, while Est-3 is autosomal with two codominant alleles and a recessive null allele and Acp exhibits three codominant alleles.

[Comparative study of protein polymorphism in the gray Ukrainian breed]

The electrophoresis of blood serum proteins in polyacrylamide gel has been used to analyze genetic variability of Grey Ukrainian and Hungarian Grey breeds of cattle. The differences in allelic frequency between the breeds and populations of Grey Ukrainian cattle are found. In cattle, post-transferrin-3, new polymorphic protein, controlled by two co-dominant alleles is detected.

Comparative gene frequencies between the Canchim breed of Brazil beef cattle and their foundation breeds

1. Four hundred and seventy-five animals of the Canchim breed from EMBRAPA-UEPAE de Sao Carlos were analyzed by starch gel electrophoresis. 2. Albumin, amylase, transferrins, carbonic anhydrase, hemoglobin and nucleoside phosphorylase gene frequencies were compared with the same frequencies in the foundation breeds, Charolais and Indubrazil. 3. Theoretical values obtained considering the 5/8 European, 3/8 Zebu admixture are near the means calculated from our results and data from literature.

Could bovine serum albumin be the initiating antigen ultimately responsible for the development of insulin dependent diabetes mellitus?

Western blotting of either a cloned rat beta-islet tumour cell extract or isolated BB rat islets with rat anti-bovine serum albumin antiserum revealed a cross-reacting protein (Mr = 69,000). A protein of similar molecular size was observed by fluorography in proteins immunoprecipitated from islet cells labelled with (35S)-methionine using anti-bovine serum albumin antiserum. In comparing the primary structure of the beta subunits of the proteins Ia, DQ and DR a region of homology with bovine serum albumin became evident. Analysis of the amino-acid homology in relation to the DR/DQ allotypes found in the human population gave a strong correlation between the combined DR and DQ homology score with bovine serum albumin and the incidence of insulin dependent diabetes mellitus.

Synthesis of antigens, cross-reactive with bovine serum albumin, by cultured neuroblastoma cells

Antisera to bovine serum albumin (BSA) react with biosynthetic products of the LAN-1 neuroblastoma cell line. This immunological reaction was shown by analysis of immunoprecipitates prepared with anti-BSA and products of this cell line intrinsically labeled by the incorporation of 3H- or 35S-labeled amino acids. Moreover, antibodies in sera from two patients with neuroblastoma precipitate intrinsically labeled macromolecules produced by these tumor cells. Release of antigens cross-reactive with BSA by neuroblastomas may explain, in part, the high levels of antibody to BSA and circulating immune complexes containing hidden or "blocked" antibodies to BSA found in some patients with this tumor.

An analysis of the heterogeneity of albumin

A simple and rapid procedure for characterization of serum albumin samples and for the isolation of fractions from fresh serum or commercial sources has been developed, based on DEAE Sepharose CL-6B ion exchange chromatography. Characterization of the fractions included sulfhydryl analysis, gel electrophoresis, and immunoelectrophoresis. Both analytical and preparative procedures were used. It has been shown that the relative content of the fractions varies from individual to individual. It has also been shown that certain fractions found in commercial preparations are artifacts which should be removed before performing serious studies with serum albumin.