Biomedical subjects

E Frolova

Publications and source records attributed to E Frolova.

6 recordsLinked to original sources

PubMed2000

Intravenous injection of major and cryptic peptide epitopes of ribotoxin, Asp f 1 inhibits T cell response induced by crude Aspergillus fumigatus antigens in mice.

Aspergillus fumigatus, a ubiquitous fungus, is implicated in the pathogenesis of a number of clinically different allergic diseases in man. Peptide-based immunotherapy may offer an alternative in patient care and management. The purpose of this study was to evaluate the role of T cell epitopes of A. fumigatus ribotoxin, Asp f 1 in inducing tolerance in mice exposed to A. fumigatus antigen. The epitope analysis in BALB/c mice using synthetic peptides of Asp f 1 demonstrated both cryptic and dominant epitopes detected from 42 through 54 and 155 through 167 aa, accordingly. Intravenous injection of these peptides markedly inhibited the response induced by the exposure to crude A. fumigatus extract in mice as evidenced by the in vitro interleukin-2 (IL-2) production and proliferation of T-lymphocytes. Cytokine transcription studies indicate that, when stimulated with the peptides in immunogenic conditions, the major peptide (aa 155-167) specific T cell clone produced only IFN-gamma, but not IL-4. The ability of both dominant and cryptic peptide epitopes of a single molecule to induce tolerance against the immune response to a multi-molecular allergen complex has significant implication for peptide-based immunotherapy.

Allergens↗

PubMed2000

The expression pattern of a novel Deltex homologue during chicken embryogenesis.

We isolated a partial cDNA encoding a novel chicken homologue of human Deltex (DTX1), a member of the Notch signaling pathway. The cDtx2 sequence showed higher homology to KIAA0937 protein (92% identical) than to DTX1 (68% identical). cDtx2 is expressed widely in the epiblast at stage 4. Later in development it is expressed in many neural and sensory structures, such as neural tube, migrating neural crest cells, epidermal placodes, cranial ganglia, and the optic and otic vesicles.

Amino Acid Sequence↗

PubMed1999

Binding of the glucose-dependent Mig1p repressor to the GAL1 and GAL4 promoters in vivo: regulationby glucose and chromatin structure.

Binding of the MIG1 repressor to the glucose-repressible GAL1 and GAL4 promoters was analyzed in vivo by cyclobutane dimer footprinting in two yeast strains that show different glucose repression responses. Mig1p binding to the two promoters in both strains was glucose-induced. In cells subject to rapid and stringent glucose repression (S288c), long-term Mig1p binding in glucose-grown cells was inhibited by the formation of a competing chromatin structure. Under conditions where glucose repression was only partially effective (gal80 - or low glucose), the chromatin structure did not form and long-term Mig1p binding was observed The same long-term binding of Mig1p was seen in cells of a different strain (W303A) that shows only partial glucose repression of the GAL1 promoter. We conclude from these experiments that Mig1p binding to glucose-repressed promoters is glucose-dependent but transient. We suggest that Mig1p functions at an early step in repression, but is not required to maintain the repressed state.

Base Sequence↗

PubMed1997

Packaging signals in alphaviruses.

Alphaviruses synthesize large amounts of both genomic and subgenomic RNA in infected cells, but usually only the genomic RNA is packaged. This implies the existence of an encapsidation or packaging signal which would be responsible for selectivity. Previously, we had identified a region of the Sindbis virus genome that interacts specifically with the viral capsid protein. This 132-nucleotide (nt) fragment lies within the coding region of the nsP1 gene (nt 945 to 1076). We proposed that the 132-mer is important for capsid recognition and initiates the formation of the viral nucleocapsid. To study the encapsidation of Sindbis virus RNAs in infected cells, we designed a new assay that uses the self-replicating Sindbis virus genomes (replicons) which lack the viral structural protein genes and contain heterologous sequences under the control of the subgenomic RNA promoter. These replicons can be packaged into viral particles by using defective helper RNAs that contain the structural protein genes (P. Bredenbeek, I. Frolov, C. M. Rice, and S. Schlesinger, J. Virol. 67:6439-6446, 1993). Insertion of the 132-mer into the subgenomic RNA significantly increased the packaging of this RNA into viral particles. We have used this assay and defective helpers that contain the structural protein genes of Ross River virus (RRV) to investigate the location of the encapsidation signal in the RRV genome. Our results show that there are several fragments that could act as packaging signals. They are all located in a different region of the genome than the signal for the Sindbis virus genome. For RRV, the strongest packaging signal lies between nt 2761 and 3062 in the nsP2 gene. This is the same region that was proposed to contain the packaging signal for Semliki Forest virus genomic RNA.

Animals↗

PubMed1997

Sindbis virus replicons and Sindbis virus: assembly of chimeras and of particles deficient in virus RNA.

Alphaviruses are a well-characterized group of positive-strand RNA viruses. The identification of cis-acting elements in their genomes and their replication strategy have made them useful as vectors for the expression of heterologous genes. In infected cells, the nonstructural proteins, required for replication and transcription of the viral genes, are translated from the genomic RNA; the structural proteins, the capsid protein that interacts with the RNA to form the nucleocapsid and the proteins embedded in the lipid envelope, are translated from a subgenomic mRNA and can be replaced by heterologous genes. Such modified genomes are self-replicating (replicons); they can be introduced into the cells by transfection and can also be packaged into extracellular particles with defective helper (DH) RNAs. The particular DH RNA determines how well it is replicated and to what extent it is packaged. One potential complication of this system has been that recombination between the replicon genome and the DH RNA may occur. The studies described here were designed to prevent recombination by expressing the capsid protein from one DH RNA and the virus membrane proteins from a second helper RNA. Recombination to yield a nonsegmented infectious virus genome would then require several independent crossover events. There is a translational enhancer located downstream of the initiating AUG in the RNA of the capsid gene that had to be conserved in the second helper to achieve high-level expression of the viral glycoproteins. For this reason, we modified the capsid protein gene in two ways: the first was to use the capsid protein gene from a different alphavirus, Ross River virus, and the second was to make deletions in that gene to maintain the translational enhancer in the RNA but to eliminate the positively charged region in the protein that should be essential for the specific and nonspecific interactions with RNA. Transfections with replicon RNA and the deleted chimeric DH RNA as the only helper resulted in the high-level production of particles that were almost completely devoid of RNA. The inclusion of a helper expressing an intact Sindbis virus capsid protein gene led to the production of high levels of packaged replicons. Recombinants were not detected even after several undiluted passages.

Amino Acid Sequence↗

PubMedDate not supplied

Ribozyme mimics as catalytic antisense reagents.

Viral and fungal infections and some cancers may be described as diseases that are characterized by the expression of certain unwanted proteins. They could be termed induced genetic disorders, with induction provided by mutation or infection. A comprehensive method to inactivate injurious genes based on their nucleic acid sequences has the potential to provide effective antiviral and anticancer agents with greatly reduced side effects. We describe a chemical approach to such gene-specific pharmaceutical agents. Our initial efforts have been to develop new chemical reagents that can carry out catalytic destruction of specific mRNA sequences. We chose hydrolysis as a chemical means of destruction, because hydrolysis is compatible with living cells. Our sequence-specific catalytic RNA hydrolysis reagents may be described as functional ribozyme mimics. Reactivity is provided by small-molecule catalysts, such as metal complexes. Specificity is provided by oligonucleotide probes. Here we report initial results on the sequence-specific, hydrolytic cleavage of mRNA from the HIV gag gene, using a ribozyme mimic. The reagent is composed of a terpyridylCu(II) complex for cleavage activity and an oligonucleotide for sequence specificity.

Animals↗