SEARCH · Search PubMed

Results for “DsRNA”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,225 records · Page 68Linked to original sources

PubMedDate not supplied

[Role of double-stranded RNA in eukaryotic gene silencing].

Data on RNA interference, that is, posttranscriptional gene silencing by homologous double-stranded (ds) RNA, are reviewed. Gene silencing caused by exogenous dsRNA in artificial systems and observed in transgenic organisms carrying additional gene copies is considered. Data are summarized on the mechanism that arose during evolution of the Drosophila melanogaster genome to suppress repetitive genes with the use of dsRNA and thereby to prevent male sterility. The role of dsRNA in inhibiting expression and transposition of mobile elements is discussed on the basis of authors own and published findings.

Animals↗

PubMed2000

[Research of toxin and plasmids of Saccharomyces cerevisiae].

Killer toxin from Saccharomyces cerevisiae SK was isolated by ultrafiltration of culture supernatants and purified by poly(ethylene glycol). The toxin migrates as one single protein band on SDS-PAGE and its molecular weight is 15 kD. The SK toxin has the greatest lethal effect on the sensitive yeast strain in the lat-lag phase. Extraction and purification of killer heretity factor(dsRNA) from SK found that M-dsRNA plasmid and L-dsRNA plasmid have different molecular lengths being 1.7 kb and 4.0 kb.

Killer Factors, Yeast↗

PubMed1998

[Comparative research on two different killer strains of Saccharomyces cerevisiae].

Using two different killer strains SK4(K1 type) and ERR1(K2 type), their killer characters were analysed and find two strains compete with each other when they are mixed and killer characters are related with the growth of strains. Different M-dsRNA plasmids in different killer strains have different molecular lengths, being 1.7 kb and 1.5 kb in SK4 and ERR1, respectively. L-dsRNA plasmids in both strains have the same molecular lengths, 4.0 kb. Cured by high temperature (38 degrees C) and U.V. (15 W, 30 cm, 5 min), killer strains lose their killer characters with the disappearance of M-dsRNA, the curing rate of killer activity is associated with strains and curing conditions. Killer toxins produced by two strains have different killer effects. Toxins of SK4 and ERR1 have the different highest killer activity at pH 4.8, 16 degrees C and pH4.2, 22 degrees C, but both of two toxins have the greatest effect on the sensitive strain in the late-log phase.

Hydrogen-Ion Concentration↗

PubMed2003

Induction of macrophage migration inhibitory factor by lysophosphatidic acid: relevance to tumor growth and angiogenesis.

Macrophage migration inhibitory factor (MIF) plays an important role not only in the immune system, but also in tumorigenesis. Lysophosphatidic acid (LPA), a unique lipid mediator, shares several biological functions with MIF, including promotion of tumor cell growth and associated angiogenesis. In this study, we investigated the signaling cross-talk between these two molecules during tumorigenesis and angiogenesis. We first examined the expression of MIF mRNA on a murine colon cancer cell line, colon 26, by LPA. We found that LPA enhanced the expression of MIF mRNA in a dose-dependent manner in vitro. In parallel, LPA stimulated cell growth and up-regulated the vascular endothelial growth factor (VEGF). These effects were dramatically blocked by 21 base double strand (ds) RNA specific for mouse MIF mRNA (RNAi). In vivo, colon 26 cells treated with MIF dsRNA were injected into the backs of mice. The size of tumor volumes became significantly smaller than that of controls. Angiogenesis examined by a Millipore chamber method was also suppressed by the MIF dsRNA. Next, we evaluated the signal transduction pathway relevant to the mitogen-activated protein kinase (MAPK) and Akt/PI3K pathways in response to LPA by RNAi. Ras activation and phosphorylation of Akt and ERK1/2 were strongly suppressed by the dsRNA. On the other hand, tyrosine phosphorylation was minimally changed by the treatment. Taken together, these results suggest that MIF could promote both tumor cell growth and angiogenesis induced by LPA via both the Ras-MAPK and Ras-Akt/PI3K signaling pathways.

Animals↗

PubMedDate not supplied

[The impact of compound of double-stranded RNA and hyaluronic acid on the parameters of non-specific resistance in mice].

The effect of yeast double-stranded RNA (dsRNA) and of hyaluronic acid (HA) compositions produced on the interferon synthesis, peritoneal phagocytic activity of macrophages and on the hematological parameters were studied in an experiment with white noninbred mice. HA was shown to enhance the dsRNA-induced interferon synthesis, to inhibit the leukopenic reaction and to produce no effect on the phagocytosis-stimulating activity. The data obtained are indicative of that HA is a promising preparation regarding its use within the interferon-inducing compositions based on dsRNA.

Administration, Cutaneous↗

PubMed2004

[Blocking with double- stranded RNA of the expression of Hes5 in rat bone marrow-derived neural stem cells].

OBJECTIVE: To examine the efficiency of exogenous small double-stranded RNA (dsRNA) in knocking down the gene expression at the post-transcription level, and investigate the factors that may influence the transfection. METHOD: The bone marrow stromal cells of SD rat were separated and cultured in vitro, followed by induction of the cells to evolve into neural stem cells using special culture medium prepared by our laboratory. Synthetic dsRNA was then transferred into the cells at varied concentrations, and the results were analyzed by Western blotting. RESULTS: The concentrations ranging from 200 to 300 nmol/L were optimal for specifically blocking the expression of Hes5, whereas the suitable concentrations for the cell survival were between 50 and 200 nmol/L. CONCLUSION: dsRNA is capable of triggering RNA interference in neural stem cells, and at appropriate concentration, it may specifically and effectively knock down endogenous gene expression without sacrificing the viability of the cells.

Animals↗

PubMed2005

Small but mighty RNA-mediated interference in plants.

RNA silencing is a conserved phenomenon of regulation of gene expression by small RNAs derived from cleavage of double-stranded RNA (dsRNA). The present review deals with three overlapping modes of small RNA-mediated silencing particularly in plants. In case of post-transcriptional gene silencing (PTGS), Dicer, an endonuclease, cleaves dsRNA to produce approximately 21nt-long small interfering RNAs (siRNAs), which guide RISC, another nuclease complex, to destroy specific target mRNAs based on sequence complementarity with the siRNA. Another class of siRNAs of 25nt-long is also produced from dsRNA by Dicer, different from that generates 21nt-long siRNA. These longer siRNAs are probably involved in systemic silencing during PTGS and guide methylation of both DNA and histone, and induce heterochromatinization and consequent transcriptional repression of the targeted gene. Both siRNA-mediated PTGS and epigenetic modification of the genome are considered as defense mechanisms to protect against invading viruses, transposons or aberrantly expressing transgenes. Regulation of expression of endogenous genes is mediated by another class of 21nt-long small RNAs called microRNAs (miRNA). Genes encoding the miRNAs are present either in the intergenic regions, introns or coding regions of the plant genome. Cleavage of a stem-loop precursor transcript called pre-miRNA, by another class of Dicer generates miRNAs, which in association with nuclease complex similar to RISC, if not identical, either degrade target mRNA or cause translational repression. The applications of RNA silencing in functional genomics and crop improvement are discussed.

Gene Expression Regulation, Plant↗

PubMedDate not supplied

[Characteristics of virus double-stranded RNA, isolated from microscopic fungi parasitizing on sugar beet].

We have carried out comparative studies of double-stranded RNA (dsRNA) of viral nature isolated from sugar beet leaves and from mycelium of microscopic fungi using different methods such as PAAG electrophoresis and by polymerase chain reaction (PCR). It was shown that the fragments of dsRNA from sugar beet leaves and from mycelium microscopic fungi had the identical electrophoretic pattern and the same size (1.8 and 2.0 kbp). Using PCR technique it was shown, that isolated dsRNA have a common template for amplification. Electron microscopy of PCR-positive mycelium allows us to detect the virus particles of the spherical form with diameter 30-40 nm. The obtained data confirm our previous suppositions, concerning the belonging of isolated dsRNAs (size 1.8 and 2.0 kbp) to new mycovirus targeted a microscopic fungus, instead of beet cryptic viruses.

Basidiomycota↗

PubMed2003

[Molecular cloning and sequencing of Dendrolimus punctatus Wenshanensis cytoplasmic polyhedrosis virus (DpwCPV) NS5 protein gene].

DpwCPV were purified from infected Dendrolimus punctatus Wenshanensis larvae by density gradient centrifugation. The genomic dsRNA segments were subsequently extracted directly from the purified polyhedra by SDS treatmen, phenol/chloroform extraction and ethanol precipitation. Defferent segments of genomic dsRNA were separated by low melting point agarose electrophoresis, and S9 dsRNA was purified after being excised from the gel. S9 RNA was denaturalized in high temperature. The primers was designed on the basis of the RNA sequence of S9 in BmCPV-1 (H strain). After RT-PCR, the amplified cDNA was cloned into the pMD18-T Vector. The NS5 protein gene of DpwCPV is found to be 977 nucleotides in length with one open reading frame in one strand. It can code a predicted protein of 320 residues (35560).

Amino Acid Sequence↗

PubMed1991

[Effect of double-stranded RNA and interferon type I on reproduction of cytomegalovirus in human fibroblasts].

Double-stranded RNAs (dsRNA) - larifan and ridostin, and recombinant interferons-alpha-2 and beta-1, manufactured in the USSR, inhibited the reproduction of CMV in cell culture. Antiviral effect depended on concentration of preparations, time of administration and m. o. i. DEAE-dextran enhances antiviral effect dsRNA. DsRNA and interferons added to cells infected with CMV at high m. o. i. enhance the viral reproduction. Among studied preparations highest antiviral effect was shown by natural leucocyte interferon (Egis). It was 10 times more active, than recombinant IFNs and in concentration of 1000 U/ml was comparable to activity of larifan (200 mg/ml).

Antiviral Agents↗

PubMed1990

[Double-stranded RNA from phage F6: its interferon-inducing and antiviral properties].

Double stranded RNA was isolated from bacteriophage phi 6 parasitizing on phytobacteria. Its interferon-inducing and antiviral activities were shown in vitro and in vivo. In the culture of L-929 cells, interferon resistant to heat and acids was synthesized. The interferon could be practically completely neutralized by specific anti-interferon serum. The phage phi 6 preparation dsRNA in the lyophilized form was studied. The preparation retained its biological activity. It was shown that a preparation containing 30 per cent of dsRNA was less toxic than a preparation containing 100 per cent of dsRNA, the difference in the interferon-inducing activity being insignificant.

Animals↗

PubMed2004

Downregulation enhanced green fluorescence protein gene expression by RNA interference in mammalian cells.

RNA interference (RNAi) is a recently observed process by which double-stranded RNA (dsRNA) directs sequence-specific degradation of messenger RNA (mRNA) in animal and plant cells. In several model systems, RNAi had been developed into a useful tool for the investigation of gene function. In order to study the effectiveness of RNAi in mammalian cells, we introduced chemically synthetic 21-nucleotide small interference RNA (siRNA) duplexes into 293T/GFP cells, which were transduced by enhanced green fluorescence protein (EGFP) gene, by means of TransIT-TKO, Oligofectamine reagent, Lipofectamine 2000 respectively. The results demonstrated that EGFP expression was significantly and specifically inhibited by the corresponding dsRNA, but not by unrelated dsRNA. In three different vectors, Lipofectamine 2000 demonstrated the highest transfection efficiency with a 48 h exposure. The decrease in EGFP fluorescence intensity was approximately 80%. Although TransIT-TKO and Oligofectamine displayed similar trends, the transfections were inefficient, and often toxic. The results also exhibited that siRNA inhibited the EGFP gene expression in a dose and time-dependent manner. Therefore, we concluded that the Lipofectamine 2000 was a better transfection reagent for RNAi. RNAi pathway seems operative in mammalian embryo cells. RNAi may be developed into a potential tool for gene therapy.

Cell Line↗

PubMed1991

Molecular cloning and characterization of W double-stranded RNA, a linear molecule present in Saccharomyces cerevisiae. Identification of its single-stranded RNA form as 20 S RNA.

Most strains of the yeast Saccharomyces cerevisiae harbor a double-stranded RNA (dsRNA) molecule, called W. We obtained W cDNA clones by random priming of denatured W dsRNA followed by reverse transcription. Sequence data of W shows that only one strand ((+)-strand) has coding capacity for a protein with 829 amino acids which spans almost the entire length of the molecule (2.5 kilobases). Within this protein we found a sequence pattern characteristic of RNA dependent RNA polymerases of (+)-strand and double-stranded RNA viruses. W has no homology with other dsRNAs found in S. cerevisiae, such as L-A, L-BC or M1. However, a (+)-strand-specific probe for W hybridized with 20-S RNA. Furthermore, W (+)-strands comigrated with 20 S RNA in strand separation gels. These results suggest that 20 S RNA is a (+)-single-stranded RNA form of W dsRNA itself or a closely related molecule.

Amino Acid Sequence↗

PubMedDate not supplied

[Antiproliferative effect of interferon inducers].

The antiproliferative effect of clinically promising interferon inducers, phage f2 ambermutant dsRNA, polyguacyl, tiloron, Tash-4, was demonstrated in Raji lymphoblastoid cells. Concentrations of the inducers producing death of 48-66% of Raji cells were determined to be: for dsRNA, 200 micrograms/ml; polyguacyl, 400 micrograms/ml; tiloron, 100 micrograms/ml; Tash-4, 200 micrograms/ml, which corresponded to the antiproliferative effect of 200 units/ml of alpha-interferon and 40 units/ml of gamma-interferon. No antiproliferative effect was observed at dsRNA, polyguacyl, and Tash-4 concentrations below 100 micrograms/ml. None of the inducers exerted the antiproliferative effect on the selected concentrations on normal human diploid cells. The results obtained explain the antitumorigenic effect of these inducers, demonstrated previously.

Burkitt Lymphoma↗

PubMed1985

Double stranded RNA and the nuclear matrix--implications for the 2-5A system.

RNA species present on rat liver nuclear matrices were investigated. Nuclear matrices prepared by extensive digestion of isolated nucleii with DNase and RNaseA followed by low and high (2M NaC1) salt washes were labelled in vitro with T4 RNA ligase and [5'-32P]pCp and the labelled RNA analysed by gel electrophoresis. Despite the extensive RNaseA treatment, a prominent RNA species migrating as a heterodisperse band of 220-300 nucleotides (termed MX220-300), was observed--only minor amounts of other RNA molecules were seen. A comparison of RNA isolated from in-vitro labelled nuclear matrices with isolated matrix RNA that was subsequently labelled, indicated that part of MX220-300 was preferentially exposed on the nuclear matrix structure. Analysis of MX220-300 indicated that it was composed of a polyadenylic acid moiety hydrogen bonded to a smaller molecule of polyuridylic acid. No evidence was found for the presence of guanosine or cytosine residues. Control experiments in which labelled polyuridylic acid was added to nucleii prior to the preparation of MX220-300, virtually excluded the possibility that the partial double stranded RNA structure was an artefact of matrix preparation. An analysis of proteins in the nuclear matrix structure that interact with double stranded (ds)RNA showed at least 2 proteins having molecular weights of 62K and 66K daltons that recognized and bound polyadenylic/polyuridylic acid. Competition experiments with unlabelled polyinosinic/polycytidylic acid indicated that these proteins specifically recognized the dsRNA structure. The 62K and 66K dalton matrix proteins that specifically bound dsRNA were observed in nuclear matrices prepared from HeLa, Ehrlich ascites tumor and rat liver cells. It is not known whether these matrix located dsRNA binding proteins have 2-5A synthetase activity. The relevance of the above findings to the 2-5A system will be discussed.

Adenine Nucleotides↗

PubMedDate not supplied

[The interferon system in ducks infected with viral hepatitis B].

The duck peripheral blood lymphocytes and spleen cells were shown to be relatively resistant to interferon induction by viral (NDV) and nonviral (dsRNA) inducers as well as to Con A induction of gamma-interferon. The concentration of the inducers had to be increased 4-5-fold to induce interferon production. Charry valley ducks produced more alpha-interferon than Peking ducks. The level of interferon production induced by NDV and dsRNA (Ridostin) was similar in DHBV-positive Peking ducks and in the control group, but in the infected Charry valley ducks interferon production was lower than in the controls (224 to 180 U/0.1 ml in NDV-induced and from 192 to 43.3 U/0.1 ml in dsRNA-induced). Early bursectomy brought down the interferon production in non-infected ducts, but in DHBV-positive bursectomized ducks (Y) the level of interferon was higher than in the control bursectomized ducks.

Animals↗

PubMed1989

[Study of immunoregulating properties of an interferon inducer in animals with various reactions to the antigen].

Influence of dsRNA isolated from killer yeast of S. cerevisiae on humoral and cellular immune responses in mice CBA/CaY and C57Bl/6Y with opposing reaction to the antigen was studied. It was shown that after administration of the yeast dsRNA preparation to the animals simultaneously with the antigen there was an increase in the number of the antibody forming cells in the spleen and the titer of hemolytic antibodies in blood serum of the animals with high and low reactions to the antigen. After sensitization with different doses of sheep red blood cells (10(7) and 10(8)) the preparation had immunomodulating action on development of DTH in mice CBA/CaY. The effect of the dsRNA preparation on the immunity system depended on the preparation dose, antigen loading and animal genotype and was the most marked in mice CBA/CaY with interferon levels in blood serum 2-3 times higher than those in mice C57Bl/6Y.

Adjuvants, Immunologic↗

PubMed1985

[Natural interferon inducers: double-stranded RNA of killer plasmids of Saccharomyces cerevisiae].

Methods for isolation and purification of yeast double spiral RNA (dsRNA) are described. The most simple method includes reprecipitation of dsRNA in solutions of lithium chloride and its interphase distribution in the system of chloroform: isoamilic alcohol: water. Preparations with the content (w/w) of dsRNA from 30 to 90 per cent were obtained. They possess a high interferon-inducing activity and an antiviral effect on the experimental infection caused by the virus of mouse encephalomyocarditis.

Animals↗