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A high-throughput alphavirus-based expression cloning system for mammalian cells.

We have developed a widely applicable functional genomics strategy based on alphavirus expression vectors. The technology allows for rapid identification of genes encoding a functional activity such as binding of a defined ligand. Complementary DNA (cDNA) libraries were expressed in mammalian cells following infection with recombinant Sindbis virus (SIN replicon particles), a member of the Alphavirus genus. Virus-infected cells that specifically bound a ligand of choice were isolated using fluorescence-activated cell sorting (FACS). Replication-competent, infective SIN replicon particles harboring the corresponding cDNA were amplified in a next step. Within one round of selection, viral clones encoding proteins recognized by monoclonal antibodies or Fc-fusion molecules could be isolated and sequenced. Moreover, using the same viral libraries, a plaque-lift assay was established that allowed the identification of secreted, intracellular, and membrane proteins.

Animals↗

Liposome-mediated CFTR gene transfer to the nasal epithelium of patients with cystic fibrosis.

We report the results of a double-blind, placebo-controlled trial in nine cystic fibrosis (CF) subjects receiving cationic liposome complexed with a complementary DNA encoding the CF transmembrane conductance regulator (CFTR), and six CF subjects receiving only liposome to the nasal epithelium. No adverse clinical effects were seen and nasal biopsies showed no histological or immuno-histological changes. A partial restoration of the deficit between CF and non-CF subjects of 20% was seen for the response to low Cl- perfusion following CFTR cDNA administration. This was maximal around day three and had reverted to pretreatment values by day seven. In some cases the response to low Cl- was within the range for non-CF subjects. Plasmid DNA and transgene-derived RNA were detected in the majority of treated subjects. Although these data are encouraging, it is likely that transfection efficiency and the duration of expression will need to be increased for therapeutic benefit.

Base Sequence↗

Local adenoviral-mediated expression of recombinant hirudin reduces neointima formation after arterial injury.

Catalytically active thrombin, acting locally, is thought to mediate neointima formation after arterial injury. We constructed an adenovirus vector, AdHV-1.2, containing a complementary DNA for the thrombin inhibitor hirudin. AdHV-1.2 directed the synthesis and secretion of biologically active hirudin from vascular cells in vitro. In vivo gene transfer of hirudin into smooth muscle cells of injured rat carotid arteries resulted in peak secretion of at least 34+/-23 pg hirudin per vessel per 24 hours, and resulted in a significant (P<0.05) 35% reduction in neointima formation. Systemic partial thromboplastin times were not affected by local hirudin expression. These results support the hypothesis that local thrombin activity contributes to neointima formation after arterial injury and suggest that local delivery of a highly specific antithrombin may constitute an effective intervention for arterial proliferative disease.

Adenoviridae↗

DmMyD88 controls dorsoventral patterning of the Drosophila embryo.

MyD88 is an adapter protein in the signal transduction pathway mediated by interleukin-1 (IL-1) and Toll-like receptors. A Drosophila homologue of MyD88 (DmMyD88) was recently shown to be required for the Toll-mediated immune response. In Drosophila, the Toll pathway was originally characterized for its role in the dorsoventral patterning of the embryo. We found that, like Toll, DmMyD88 messenger RNA is maternally supplied to the embryo. Here we report the identification of a new mutant allele of DmMyD88, which generates a protein lacking the carboxy-terminal extension, normally located downstream of the Toll/IL-1 receptor domain. Homozygous mutant female flies lay dorsalized embryos that are rescued by expression of a transgenic DmMyD88 complementary DNA. The DmMyD88 mutation blocks the ventralizing activity of a gain-of-function Toll mutation. These results show that DmMyD88 encodes an essential component of the Toll pathway in dorsoventral pattern formation.

Adaptor Proteins, Signal Transducing↗

Effects of ligand and thyroid hormone receptor isoforms on hepatic gene expression profiles of thyroid hormone receptor knockout mice.

Little is known about the overall patterns of thyroid hormone (Th)-mediated gene regulation by the main Th receptor (Tr) isoforms, Tr-alpha and Tr-beta, in vivo. We used 48 complementary DNA microarrays to examine hepatic gene expression profiles of wild-type and Thra and Thrb knockout mice under different Th conditions: no treatment, treatment with 3,3',5-triiodothyronine (T(3)), Th-deprivation using propylthiouracil (PTU), and treatment with a combination of PTU and T(3). Hierarchical clustering analyses showed that positively regulated genes fit into three main expression patterns. In addition, only a subpopulation of target genes repressed basal transcription in the absence of ligand. Interestingly, Thra and Thrb knockout mice showed similar gene expression patterns to wild-type mice, suggesting that these isoforms co-regulate most hepatic target genes. Differences in the gene expression patterns of Thra/Thrb double-knockout mice and Th-deprived wild-type mice show that absence of receptor and of hormone can have different effects. This large-scale study of hormonal regulation reveals the functions of Th and of Tr isoforms in the regulation of gene expression patterns.

Animals↗

Control of splicing efficiency by the mouse histone H2a element in a murine leukemia virus-based retroviral vector.

While using various human complementary DNA (cDNA) sequences in the context of the murine leukemia virus (MLV)-based retroviral vector, it was found that a retroviral vector containing some human cDNA sequences produces unusually low viral titer. One of those sequences is that for the human IL-1 receptor antagonist protein (IL1RN). The RNA analysis showed that a cryptic splice acceptor sequence is present in the middle of its coding region, resulting in the deletion of the packaging signal sequence and the removal of some coding sequences that lead to low viral titer and a low level of the transgene product. We tested whether the mouse Hist2h2aa1 element (mH2aE), previously shown to suppress the splicing function, could inhibit the cryptic splicing in the context of MLV-based retroviral vectors. It was found that the mH2aE could efficiently suppress such unwanted splicing event, thus increasing the amount of unspliced transcript, which eventually led to the increase in the level of IL1RN expression and viral titer. The mH2aE could also be used to control unusually high splicing activity. Our data suggested that the mH2aE could be used for the fine-tuning of the splicing process, thus improving the level of gene expression and viral titer in the context of retroviral vectors.

Base Sequence↗

Csa-19, a radiation-responsive human gene, identified by an unbiased two-gel cDNA library screening method in human cancer cells.

A novel polymerase chain reaction (PCR)-based method was used to identify candidate genes whose expression is altered in cancer cells by ionizing radiation. Transcriptional induction of randomly selected genes in control versus irradiated human HL60 cells was compared. Among several complementary DNA (cDNA) clones recovered by this approach, one cDNA clone (CL68-5) was downregulated in X-irradiated HL60 cells but unaffected by 12-O-tetradecanoyl phorbol-13-acetate, forskolin, or cyclosporin-A. DNA sequencing of the CL68-5 cDNA revealed 100% nucleotide sequence homology to the reported human Csa-19 gene. Northern blot analysis of RNA from control and irradiated cells revealed the expression of a single 0.7-kilobase (kb) messenger RNA (mRNA) transcript. This 0.7-kb Csa-19 mRNA transcript was also expressed in a variety of human adult and corresponding fetal normal tissues. Moreover, when the effect of X- or fission neutron-irradiation on Csa-19 mRNA was compared in cultured human cells differing in p53 gene status (p53-/- versus p53+/+), downregulation of Csa-19 by X-rays or fission neutrons was similar in p53-wild type and p53-null cell lines. Our results provide the first known example of a radiation-responsive gene in human cancer cells whose expression is not associated with p53, adenylate cyclase or protein kinase C.

Age Factors↗

Stabilisation of nucleic acid secondary structures by oligonucleotides with an additional nucleobase; synthesis and incorporation of 2'-deoxy-2'-C-(2-(thymine-1-yl)ethyl)uridine.

A nucleoside with two nucleobases is incorporated into oligonucleotides. The synthetic building block, 2'-deoxy-2'-C-(2-(thymine-1-yl)ethyl)uridine, 2, is prepared from uridine via 5',3'-TIPDS-protected 2'-deoxy-2'-C-allyluridine by an oxidative cleavage of the allyl group, a Mitsunobu reaction for the introduction of thymine and appropriate deprotection reactions. This compound is converted into a DMT-protected phosphoramidite and incorporated once into a 13-mer oligodeoxynucleotide sequence, once in an isosequential LNA-modified oligodeoxynucleotide and four times in the middle of a 12-mer oligodeoxynucleotide. These sequences are mixed with different complementary DNA and RNA sequences in order to study the effect of the additional nucleobase in duplexes, in bulged duplexes and in three-way junctions. The first additional thymine is found to be well-accommodated in a DNA-RNA duplex, whereas a DNA-DNA duplex was slightly destabilised. A three-way junction with the additional thymine in the branching point is found to be stabilised in both a DNA-DNA and a DNA-RNA context but destabilised where the modified LNA-sequence is used. In a Mg2+-containing buffer, however, the relative stability of the three-way junctions is found to be opposite with especially the LNA-modified DNA-DNA complex being significantly stabilised by the additional nucleobase.

Base Pairing↗

Sequence and biochemical similarities between the luciferases of the glow-worm Lampyris noctiluca and the firefly Photinus pyralis.

A full-length clone encoding Lampyris noctiluca (British glow-worm) luciferase was isolated from a complementary DNA (cDNA) expression library constructed with MRNA extracted from light organs. The luciferase was a 547-residue protein, as deduced from the nucleotide sequence. The protein was closely related to those of other lampyrid beetles, the similarity to Photinus pyralis luciferase being 84% and to Luciola 67%. In contrast, Lampyris luciferase had less sequence similarity to the luciferases of the click beetle Pyrophorus, at 48%. Engineering Lampyris luciferase in vitro showed that the C-terminal peptide containing 12 amino acids in Photinus and 9 amino acids in Lampyris was essential for bioluminescence. The pH optimum and the Km values for ATP and luciferin were similar for both Photinus and Lampyris luciferases, although the light emitted by the latter shifted towards the blue and was less stable at 37 degrees C. It was concluded that the molecular and biochemical properties were not sufficient to explain the glowing or flashing of the two beetles Lampyris and Photinus.

Adenosine Triphosphate↗

The bovine fibroblast growth factor receptor 3 (FGFR3) gene is not the locus responsible for bovine chondrodysplastic dwarfism in Japanese brown cattle.

Fibroblast growth factor receptor 3 (FGFR3) is one of the four distinct membrane-spanning tyrosine kinase receptors for fibroblast growth factors. The FGFR3 is a negative regulator of endochondral ossification and mutations in the FGFR3 gene have been found in patients of human hereditary diseases with chondrodysplastic phenotypes. Recently, we mapped the locus responsible for hereditary chondrodysplastic dwarfism in Japanese brown cattle to the distal region of bovine chromosome 6 close to the FGFR3 gene, suggesting that FGFR3 was a positional candidate gene for this disorder. In the present study, we isolated complementary DNA (cDNA) clones containing the entire coding region of the bovine FGFR3 gene. Comparison of the nucleotide sequence between affected and normal animals revealed no disease-specific differences in the deduced amino acid sequences. We further refined the localization of FGFR3 by radiation hybrid mapping, which is distinct from that of the disease locus. Therefore we conclude that bovine chondrodysplastic dwarfism in Japanese brown cattle is not caused by mutation in the FGFR3 gene.

Animals↗

Intragraft expression of transforming growth factor beta1 gene in isolated glomeruli from human renal transplants.

BACKGROUND: Experimental evidence suggests that transforming growth factor (TGF) beta1 is a fibrogenic cytokine. The histopathological changes of chronic renal allograft nephropathy are dominated by fibrotic changes and TGF-beta may have an important aetiological role. This study investigated the relationship between intragraft TGF-beta gene expression and extracellular matrix protein deposition in human renal allografts. METHODS: Sixteen cadaveric renal transplant recipients immunosuppressed with cyclosporin and steroids were studied. Individual glomeruli were isolated from protocol needle-core biopsies and, following messenger RNA extraction, intragraft gene expression was studied by reverse transcriptase-polymerase chain reaction. Collagen III deposition in these renal transplant biopsies was examined by immunohistochemistry and quantified by computerized histomorphometry. RESULTS: There was a positive correlation between renal cortical collagen III immunostaining and the levels of glomerular complementary DNA for TGF-beta1. CONCLUSION: TGF-beta1 is a profibrotic influence in human renal transplants. The methods described should prove of benefit in investigating the mechanisms of chronic renal allograft damage.

Biopsy, Needle↗

Characterization of the Sialokinin I gene encoding the salivary vasodilator of the yellow fever mosquito, Aedes aegypti.

The gene encoding sialokinin I, the principal vasodilatory peptide of Aedes aegypti, has been isolated and characterized. Degenerate oligonucleotide primers based on peptide amino acid sequence were used to amplify a gene fragment from messenger RNA (mRNA) isolated from female salivary glands. The amplification product was used to probe a salivary gland complementary DNA (cDNA) library, and a number of corresponding cDNAs were isolated and their primary sequence determined. Analysis of the conceptual translation product of a 406-bp cDNA indicates that sialokinin I is expressed as a preprosialokinin and is subsequently post-translationally processed to the active peptide. Northern analysis revealed a 490-bp transcription product expressed exclusively in female salivary glands, and hybridization in situ of probes to RNA in whole tissues localized gene expression to the medial lobe of female salivary glands. Screening of an Ae. aegypti genomic library with the cDNA resulted in the isolation of a clone containing the gene, designated Sialokinin I (Sia I). Comparison of the cDNA with the genomic clone reveals two introns of 62 bp and 833 bp. Primer extension analysis showed that several transcription initiation sites are present. Southern analysis of genomic DNA shows that Sia I is most probably a single-copy gene. Similarities of the Sia I gene product with other genes are confined to the region encoding the active decapeptide.

Aedes↗

Bovine tryptases. cDNA cloning, tissue specific expression and characterization of the lung isoform.

A complementary DNA encoding a new bovine tryptase isoform (here named BLT) was cloned and sequenced from lung tissue. Analysis of sequence indicates the presence of a 26-amino acid prepro-sequence and a 245 amino acid catalytic domain. It contains six different residues when compared with the previously characterized tryptase from bovine liver capsule (BLCT), with the most significant difference residing at the primary specificity S1 pocket. In BLT, the canonical residues Asp-Ser are present at positions 188-189, while in BLCT these positions are occupied by residues Asn-Phe. This finding was confirmed by mass fingerprinting of the peptide mixture obtained upon in-gel tryptic digestion of BLT. Analysis by gel filtration of the purified protein shows that BLT is probably tetrameric, similar to the previously identified tryptases from other species, with monomer migrating as 35-40 kDa multiple bands in SDS/PAGE. As expected, the catalytic abilities of the two bovine tryptases are different. The specificity constant values (kcat/Km) assayed with model substrates are 10- to 60-fold higher in the case of BLT. The tissue-specific expression of the two tryptases was evaluated at the RNA level by analysis of their different restriction patterns. In lung, only BLT was found to be expressed, while in liver capsule only BLCT is present. Both isoforms are distributed in similar amounts in heart and spleen. Analysis of the two gene sequences reveals the presence of several recognition sequences in the promoter regions and suggest a role for hormones in governing the mechanism of tissue expression of bovine tryptases.

Amino Acid Sequence↗

Sialic-acid-binding lectin from the slug Limax flavus--cloning, expression of the polypeptide, and tissue localization.

A cDNA library of Limax flavus was constructed and screened for sialic-acid-specific lectins. Complementary DNA clones were categorized into seven groups corresponding to closely related but different sequences. Group 1 clones contained an ORF encoding 199 amino acids including a sequence identical to the partial amino acid sequence obtained from the lectin protein. Within its 1074-bp 3' untranslated region, ten closely related 60-bp sequence repeats were found. Group 2 clones contained an ORF encoding a polypeptide chain of the same number of amino acid residues, with 89.1% overall identity to that of the group 1 and eight 60-bp repeat sequences in the 3' untranslated region. The remaining groups of clones contained ORF with highly similar full or partial sequences, with or without 60 bp repeats in the 3' untranslated region. The large number of closely related but different cDNA clones obtained indicated that the slug sialic-acid-specific lectin gene is a member of a multigene family. The lectin amino acid sequence showed significant similarity with the fibrinogen domain of human tenascin-C, with a human C-type serum lectin, and with pig ficolin. Immunostaining analysis of slug tissue for the lectin indicated that it is present primarily on the epidermal surface and in mucous glands. Recombinant slug lectin protein lacking the 20-amino-acid N-terminal signal sequence produced in a bacterial expression system from a group-1 clone accumulated as aggregates in inclusion bodies, suggesting that large-scale production of the active agglutinin may be possible.

Amino Acid Sequence↗

Hev b 9, an enolase and a new cross-reactive allergen from hevea latex and molds. Purification, characterization, cloning and expression.

Natural rubber latex allergy is an IgE-mediated disease that is caused by proteins that elute from commercial latex products. A complementary DNA (cDNA) coding for Hev b 9, an enolase (2-phospho-D-glycerate hydrolyase) and allergen from latex of the rubber tree Hevea brasiliensis, was amplified by PCR. The PCR primers were designed according to conserved regions of enolases from plants. The obtained cDNA amplification product consisted of 1651 bp and encoded a protein of 445 amino-acid residues with a calculated molecular mass of 47.6 kDa. Sequence comparisons revealed high similarities of the Hevea latex enolase to mold enolases that have been identified as important allergens. In addition, the crucial amino-acid residues that participate in the formation of the catalytic site and the Mg2+ binding site of enolases were also conserved. Hevea latex enolase was produced as a recombinant protein in Escherichia coli with an N-terminal hexahistidyl tag, and purified by affinity chromatography. The yield amounted to 110 mg of purified Hev b 9 per litre of bacterial culture. The recombinant allergen bound IgE from latex, as well as mold-allergic patients, in immunoblot and ELISA experiments. The natural enolase was isolated from Hevea latex by (NH4)2SO4 precipitation and ion exchange chromatography. The natural and the recombinant (r)Hev b 9 showed equivalent enzymatic activity. Patients' IgE-antibodies preincubated with rHev b 9 lost their ability to bind to natural (n) Hev b 9, indicating the identity of the B-cell epitopes on both molecules. Cross-reactivity with two enolases from Cladosporium herbarum and Alternaria alternata was determined by inhibition of IgE-binding to these enolases by rHev b 9. Therefore, enolases may represent another class of highly conserved enzymes with allergenic potentials.

Adult↗

Cloning and expression in Pichia pastoris of a blue mussel (Mytilus edulis) beta-mannanase gene.

Using PCR, cloning and sequencing techniques, a 1.1-kb complementary DNA fragment encoding for a beta-mannanase (mannan endo-1,4-beta-mannosidase, EC 3.2.1.78) has been identified in the digestive gland of blue mussel, Mytilus edulis. The cDNA sequence shows significant sequence identity to several beta-mannanases in glycoside hydrolase family 5. The beta-mannanase gene has been isolated and sequenced from gill tissue of blue mussel and contains five introns. The beta-mannanase has been expressed extracellularly in Pichia pastoris using the Saccharomyces cerevisiae alpha-factor signal sequence. The beta-mannanase was produced in a 14-L fermenter with an expression level of 900 mg.L-1. The expression level is strongly affected by the induction temperature. A two-step purification procedure, composed of a combination of immobilized metal ion affinity chromatography and ion exchange chromatography, is required to give a pure beta-mannanase. However, due to post-translational modifications, structural varieties regarding molecular mass and isoelectric point were obtained. The specific activity of the purified recombinant M. edulis beta-mannanase was close to that of the wild-type enzyme. Also pH and temperature optima were the same as for the native protein. In conclusion, P. pastoris is regarded as a suitable host strain for the production of blue mussel beta-mannanase. This is the first time a mollusc beta-mannanase has been characterized at the DNA level.

Amino Acid Sequence↗

Novel human and mouse genes encoding a shank-interacting protein and its upregulation in gastric fundus of W/WV mouse.

BACKGROUND AND AIMS: A division of labor exists between different classes of interstitial cells of Cajal (ICC) in the gastrointestinal tract. In the stomach and small intestine, ICC at the level of the myenteric plexus (IC-MY) act as slow wave pacemaker cells, whereas intramuscular ICC (IC-IM) in the stomach act as intermediaries in enteric motor neurotransmission. The muscle layers of the gastric fundus do not have IC-MY, therefore electric slow waves are not generated. Intramuscular ICC are absent in the gastric fundus of W/WV mutant mice, and excitatory and inhibitory motor nerve responses are reduced in these tissues. The absence of IC-IM in W/WV mutants in the fundus provides a unique opportunity to study the molecular changes that are associated with the loss of these cells. METHODS: The tissue gene expression of wild-type and W/WV mice from gastric fundus was assayed using a murine microarray chip analysis displaying a total of 8734 elements. RESULTS: Twenty-one queries were differentially expressed in wild-type and W/WV mice. One candidate gene, encoding a novel protein homologous to rat Shank-interacting protein (Sharpin) was significantly upregulated in fed and starved W/WV mice. The full-length clone of the murine gene and its human counterpart were isolated and designated as Shank-interacting protein-like 1 (SIPL1). Human SIPL1 complementary DNA encodes a protein of 345 amino acids. This gene was localized to chromosome 8. SIPL1 was abundantly expressed in human stomach and small intestine, and scarcely expressed in cecum and rectum. CONCLUSIONS: Gene analysis showed that SIPL1 differentially express in the gastric fundus of normal and W/WV mice. The upregulation of SIPL1 in the fundus of W/WV mice, and expression in the upper gastrointestinal tract suggest that the SIPL1 gene could be associated with ICC function in mice and humans.

Amino Acid Sequence↗