Poly(A)-containing RNA from the spleens of mice with Chagas' disease triggers in vitro macrophage resistance to Trypanosoma cruzi

Mouse peritoneal macrophages exposed to the RNA from the spleens of mice infected with Trypanosoma cruzi (iRNA) exhibit enhanced resistance to this parasite. The poly(A)-containing iRNA was found to be the active fraction. No such activity was observed in macrophages incubated with RNA from normal mice (nRNA) or with synthetic poly A.     

Nonselective inhibition of messenger RNA translation by highly purified low molecular weight RNA species from ribosomal salt wash of chick embryonic muscle

A low molecular weight RNA species, in the 70–90 nucleotide size range (iRNA), has been purified from the ribosomal salt wash of chick embryonic muscle by a combination of DEAE-cellulose and hydroxyapatite chromatography. This method yields iRNA free from contaminating tRNA and gives better and more reproducible yields than those obtained with our previous method involving lengthy dialysis of the salt wash. The iRNA at a concentration of 20–80 ng range strongly inhibits the translation of homologous and heterologous mRNAs i.e. chick muscle poly(A)⁺mRNA and rabbit globin mRNA; uncapped mRNA; and poly(A)^-mRNA in micrococcal nuclease-treated reticulocyte lysate indicating that inhibition by iRNA is nonselective in nature. The translation of endogenous globin mRNA and polysomes in the lysate is strikingly less sensitive to iRNA suggesting that the initiation step is primarily affected by iRNA. The iRNA does not appear to be double-stranded RNA. It is concluded that iRNA is distinct from other low molecular weight RNA species described in the literature which modulate protein synthesis in cell-free systems.     

Ribonucleic acid in the immune response

Summary In the studies of experimental salmonellosis, immunization of mice with a live vaccine SER of S. enteritidis was found to be effective against further infection with virulent S. enteritidis 116-54. Macrophages obtained from the peritoneal cavity, subcutaneous tissue or liver of immunized mice inhibited intracellular growth of bacteria and resisted cell degeneration caused by engulfment of virulent 116-54 bacteria. This immunity was called cellular immunity.We discovered by chance in 1961 a transfer agent of immunity (TA) from the culture fluid of immunized macrophages. This agent is RNA in nature and can be extracted from the spleen, peritoneal exudate cells or the lymph node of immunized animals and is called immune (i) RNA. We could demonstrate antibody activity in macrophages treated in vitro or in vivo with iRNA by the immune adherence hemagglutination technique.Cellular immunity against tumor cells could be transferred in vitro or in vivo to lymphocytes through iRNA prepared from the spleen cells of syngeneic, allogeneic and xenogeneic animals immunized with the tumor cells.We prepared iRNA against antigens capable of inducing humoral antibody production in animals, i.e., RBCs, bacterial toxin, bacterial flagella and hapten-protein conjugates. Serum antibody was not demonstrated in recipient animals of iRNAs by single or repeated injections of these agents. However, in these animals an increase in the number of specific antibody-carrying cells was found as rosette-formers. It was found further that prior injection of iRNA could induce immunologic memory and produced a high titer of humoral antibody after a boosting stimulation with a small dose of the corresponding antigen. The required interval between the first iRNA and the second antigenic stimulation, and the minimal effective doses of iRNA and antigen are described.We studied the interaction of iRNA with either T- or B-cells and with both cells using adoptive transfer system, athymic nude mice and neonatally thymectomized (NT) mice. Immune RNAs against T-dependent and T-independent antigens could not induce the proliferation of antibody-carrying cells in cyclophosphamide-treated (B-cell depleted) mice. But these agents could induce the proliferation of rosette-formers, implying that iRNAs can replace some role of T-cells even against T-dependent antigens. B-cells can be directly activated by treatment with iRNA against both T-dependent and T-independent antigens, and they differentiated into rosette-formers.Passive transfers of iRNA were successful in establishing immunity against infection with S. enteritidis, or immunity to Salmonella flagella, RBCs and hapten-protein conjugates. The ability of iRNA to confer a secondary response of antibody formation is serially and passively transmissible in recipient animals. These facts suggest the presence of some mechanism that is responsible for the amplification of antigenic stimulation in the immune response. The RNA-dependent RNA polymerase and RNA-dependent DNA polymerase are presented and their role in the immune response is discussed.     

The Inhibitory Effect of Staphylococcus epidermidis Slime on the Phagocytosis of Murine Peritoneal Macrophages Is Interferon-Independent

The extracellular slime produced by Staphylococcus epidermidis has been shown to interfere with several human neutrophil functions in vitro, such as chemotaxis, degranulation and phagocytosis. Slime production has been suggested as a useful marker for clinically significant infections with coagulase-negative Staphylococcus. Since the main role of macrophages in defense mechanisms is phagocytosis, the effect of slime on the phagocytic activity of macrophages was investigated. The phagocytic activity of murine peritoneal macrophages treated with slime in vitro decreased in a dose-dependent fashion. A similar decrease was also observed in macrophages isolated from mice that had previously received intraperitoneal injection of slime. To investigate whether interferon also plays a role in this process, mice were treated with interferon or an interferon inducer, polyinosinic-polycytidylic acid (poly I:C), together with slime before macrophage isolation. The slime-suppressed phagocytic activity of macrophages was partially relieved by both agents, and the recovery effect of poly I:C in slime-suppressed phagocytosis of macrophages in vivo might be attributed to the increased interferon level in peritoneal fluid and sera. However, when slime was given to poly I:C-pretreated mice, the phagocytic activity remained suppressed. Thus, it appears that slime is able to suppress the phagocytic activity of macrophages regardless of the state of macrophage activation by poly I:C. The results suggest that the inhibition of phagocytosis by S. epidermidis slime may be independent from the activation of interferon.     

Experimental Salmonellosis

An immune ribonucleic acid (RNA) preparation was obtained from the spleens of mice immunized with a live vaccine of Salmonella enteritidis. When peritoneal macrophages were infected with S. enteritidis 116–54 which had been treated by mixed cultivation with the peritoneal exudate cells of mice previously treated with an immune RNA preparation, they showed cellular resistance against the infecting bacteria. According to the results described previously and those described in this article, it can be concluded that the cellular resistance against an infection with S. enteritidis is traceable to a cellular antibody (or antibodies) detected in macrophages of mice immunized with a live vaccine of the same organism or of mice treated in vivo (or in vitro) with an immune RNA preparation.     

Cells participating in immunologic memory induced with RNA from the spleens of immunized mice

Ribonucleic acid (immune RNA, iRNA) extracted from the spleens of mice immunized with heterologous red blood cells induced antigen-specific immunologic memory. The type of cells (T cells, B cells) which participate in immunologic memory induced with iRNA was investigated. Immune RNA-primed T cells cooperated with normal, iRNA-primed or antigen-primed B cells and induced a high IgM response. Immune RNA-primed B cells did not cooperate with normal T cells, but did with iRNA- or antigen-primed T cells. The activities of iRNA-primed T and B cells were antigen-specific.     

Studies on the nature and role of polyadenylated RNA in spore development of Bacillus subtilis

Summary cDNA probes synthesized on poly(A)RNAs isolated from sporulating cells of Bacillus subtilis were used for hybridization studies with RNAs derived from cells at different stages of growth and sporulation. It was shown that these cDNAs hybridized only to RNA from sporulating cells. No hybridization was observed if total RNA isolated from vegetative cells or from stationary phase cells of a zero stage asporogenic mutant was used. The hybridization studies also indicate that at each sporulation stage different poly(A)RNA species are synthesized. Furthermore, the hybridization kinetics have clearly demonstrated the existence of three distinct abundance classes of poly(A)RNA similar to those observed in eukaryotic cells. BamHI endonuclease restriction fragments of B. subtilis DNA that were found to hybridize to labeled poly(A)RNA were ligated to the pHV33 vector and hybrid clones that hybridized efficiently to poly(A)RNA were selected. Among these, three have been found to carry the spoOB gene.These results strongly suggest that the appearance of poly(A)RNA can be correlated to the expression of spore genes.     

Identification of the substrates of the casein kinase II associated with non-polysomal messenger ribonucleoproteins of A. salina cryptobiotic embryos

The association of a protein kinase with cytoplasmic non-polysomal messenger ribonucleoproteins is demonstrated by chromatography on oligo(dT)-cellulose and sucrose gradient centrifugation. The cAMP-independent enzyme is inhibited by caffeine and poly(L)-glutamic acid and is classified as a casein kinase II. Among the exogenous proteins initiation factor eIF2 is the best substrate and is 7.8 times more efficiently phosphorylated than casein. Endogenous mRNP protein substrates have a Mr of 125000, 65000, 38000, 26000 and 23500. The main phosphate acceptor is the Mr38000 poly(A)-binding protein. Dephosphorylation of the poly(A)-binding protein by protein phosphatases decreases its RNA binding property. The effect of phosphorylation-dephosphorylation of mRNP proteins on the initiation of protein synthesis is discussed.Abbreviations PMSF phenylmethanesulfonyl fluoride - mRNP messenger ribonucleoprotein - iRNA small inhibitor RNA - eIF2 eukaryotic initiation factor 2     

小鼠肝脏MicroRNA的提取与分离

本文对小鼠肝脏microRNA进行分离制备及相关性功能研究.采用poly(A)加尾方法,分离提取小鼠肝脏中的microRNA;利用T4 RNA连接酶,在microRNA两端加上连接引物,通过RT PCR制备microRNA的cDNA文库;经过对cDNA文库的质粒连接,克隆测序获得microRNA. 结果显示：获得4条有效序列,其中包括2条已知序列miR 122和2条未知小分子RNA序列.经查证, 2条microRNA片段在miRBase库中未有记录,在二级结构分析中可形成茎环结构,符合microRNA的特征. BLAST比对显示： 2个序列位于小鼠载脂蛋白B基因和小鼠28S核糖体RNA上,可能与基因调控有关,其功能有待进一步研究.     

Transfer Agent of Immunity

An immune ribonucleic acid (RNA) was extractable from the spleen cells of mice hyperimmunized with live vaccine of Salmonella enteritidis. The RNA was capable of inducing cellular immunity and developing cellular antibody in the peritoneal macrophages of mice injected with this agent. It was found that cellular immunity was detectable even 90 days after injection in the peritoneal macrophages of mice which had received an intraperitoneal injection with this agent. Results of serial passive transfers of cellular immunity through immune RNA led us to the conclusion that this agent does not contain antigen or fragment thereof and may replicate actively in the recipient cells, although the mechanism still remains to be elucidated. The development of cellular immunity by immune RNA was inhibited by puromycin but not by actinomycin D. However, serial passive transfers of cellular immunity through immune RNA was inhibited by treatment of recipient mouse with actinomycin D, implying the role of DNA-dependent RNA polymerase in the processing of immune RNA in recipient cells. Using these results, the role of immune RNA and the possible mechanisms of immune RNA replication are discussed.     

The cytoplasmic 4 S translation inhibitory RNA species of chick embryonic muscle. Effect on mRNA binding to 43 S initiation complex

A cytoplasmic 10 S ribonucleoprotein (iRNP) isolated from chick embryonic muscle is a potent inhibitor of mRNA translation in vitro and contains a 4 S translation inhibitory RNA species (iRNA) (Sarkar, S., Mukherjee, A. K., and Guha, C. (1981) J. Biol. Chem. 256, 5077-5086). Using an in vitro assay system, we show that the iRNA has no effect on the elongation phase of peptide synthesis. iRNA inhibits translation at the initiation step by inhibiting mRNA binding to 43 S initiation complexes. The iRNA does not inhibit the binding of Met-tRNAf to the 40 S ribosomal subunit, but rather causes an increase in the level of 43 S initiation complexes in the reticulocyte lysate. The formation of the 80 S initiation complex from the 43 S complex is specifically blocked in the presence of iRNA. The significance of these results in relation to biological function of iRNA is discussed.     

Degradation of maternal poly(A)-containing RNA during early embryogenesis of an insect (Smittia spec., chironomidae,diptera)

Summary Eggs of the chironomid midgeSmittia spec. were shown to contain maternal rRNA, tRNA and poly(A)-containing RNA. The ribonucleoprotein spectrum consisted of monosomes, ribosomal subunits, and subribosomal particles, whereas polysomes could be detected only in small amounts. Poly(A)-containing RNA was found in different regions of the RNP spectrum, mainly between 15 S and 60 S. After labelling maternal RNA by feeding tritiated uridine to the larvae, the radioactivity associated with poly(A)-containing RNA accounted for about 4% of the label in the total RNA extracted from newly deposited eggs. About half of the radioactivity in the poly(A)-containing RNA was lost between egg deposition and an advanced blastoderm stage. The loss was accompanied by both a decrease in the size of the poly(A)-containing RNA molecules and a shift of poly(A)-containing RNP particles to less dense regions in sucrose gradients. Comparison with poly(A)-containing RNA synthesized by the embryo indicates that the reduction in size of maternal poly(A)-containing RNA is not artifactual but reflects its degradation after the formation of blastoderm.     

A comparison of sequence complexity of nuclear and polysomal poly(A)+ RNA from different developmental stages ofXenopus laevis

Summary Nuclear poly(A)⁺ and polysomal poly(A)⁺ RNA were isolated from gastrula and early tadpole stages of the amphibianXenopus laevis. Complementary DNA was synthesized from all RNA preparations. Hybridization reactions revealed that at least all abundant and probably most of the less frequent nuclear and polysomal poly(A)⁺ RNA species present at the gastrula stage are also present at the early tadpole stage. On the other hand, there are nuclear RNA sequences at the latter stage which appear, if at all, only at lower concentrations at the gastrula stage. The polysomal poly(A)⁺ RNA hybridization reactions suggest the existence of polysomal poly(A)⁺ RNA sequences at early tadpole stages which are not present in the corresponding gastrula stage RNA.By cDNA hybridization with poly(A)^– RNA it could be shown that most of the poly(A)⁺ containing RNA sequences transcribed into cDNA were also present within the poly(A)^– RNA. It was estimated, that these sequences are 10 fold more abundant within the poly(A)^– polysomal RNA and 3–6 more abundant within the poly(A)^– nuclear RNA as compared to the poly(A)⁺ RNAs.     

Differential induction of antiviral effects against West Nile virus in primary mouse macrophages derived from flavivirus-susceptible and congenic resistant mice by alpha/beta interferon and poly(I-C)

A cell model of primary macrophages isolated from the peritoneal cavity of flavivirus-susceptible and congenic resistant mice has been used to study the extent and kinetics of antiviral effects against West Nile virus upon priming with alpha/beta interferon (IFN-alpha/beta) or poly(I-C) (pIC). The pattern of flavivirus resistance expressed after priming of cells in this model was in good agreement with the pattern of flavivirus resistance described in the brains of the corresponding mouse strains. While priming with either IFN-alpha/beta or pIC completely blocked flavivirus replication in macrophages from resistant mice, it only transiently reduced flavivirus replication in macrophages from susceptible mice. It was only the combined pretreatment with IFN-alpha/beta and pIC that elicited strong antiviral responses that completely prevented flavivirus replication in macrophages from susceptible mice. Primary macrophages isolated from the blood of healthy human donors expressed a similar need for double-stranded RNA (dsRNA) cofactor in developing efficient antiviral responses against West Nile virus. These findings reveal that the inefficient IFN-alpha/beta-induced antiviral effects against flaviviruses in cells from susceptible hosts could be successfully complemented by an external dsRNA factor leading to the complete eradication of the virus. This treatment appears to compensate for the lack of an inborn resistance mechanism in cells from the susceptible host. Furthermore, it may also provide useful clues for the prevention and treatment of flavivirus infections.     

The size of poly(A)-containing RNAs in Drosophila melanogaster embryos

The size range of poly(A)-containing RNA from Drosophila melanogaster embryos has been estimated by hybridization with ³H-labeled poly(U) and subsequent fractionation on sucrose gradients. The median size of nuclear poly(A)-containing RNA is about 30 S (6000 nucleotides), and the median size of cytoplasmic poly(A)-containing RNA is about 17 S (1800 nucleotides). The relationship of these sizes to messenger RNA needed to code for protein and to the length of DNA contained in a chromomere is discussed.Research grant support was provided by NIH (6M35558; HD-00266) and NSF (GB-30600).     

Short interfering RNA delivered by a hybrid nanoparticle targeting VEGF: Biodistribution and anti-tumor effect

BackgroundThe use of RNA interference (iRNA) therapy has proved to be an interesting target therapy for the cancer treatment; however, siRNAs are unstable and quickly eliminated from the bloodstream. To face these barriers, the use of biocompatible and efficient nanocarriers emerges as an alternative to improve the success application of iRNA to the cancer, including breast cancer.ResultsA hybrid nanocarrier composed of calcium phosphate as the inorganic phase and a block copolymer containing polyanions as organic phase, named HNPs, was developed to deliver VEGF siRNA into metastatic breast cancer in mice. The particles presented a rounded shape by TEM images with average size measured by DLS suitable and biocompatible for biomedical applications. The XPS and EDS spectra confirmed the hybrid composition of the nanoparticles. Moreover, after intravenous administration, the particles accumulated mainly in the tumor site and kidneys, which demonstrates the tumor targeting accumulation through the Enhanced Permeability and Retention Effect (EPR). A significant decrease in size of the tumors treated with the nanoparticles containing siVEGF (HNPs-siVEGF) was observed and the reduction was related to enhanced tumor accumulation of siRNA as well as in vivo VEGF silencing at gene and protein levels.ConclusionThe hybrid system prepared was successful in promoting the RNAi effect in vivo with very low toxicity.General significanceThis study shows the valuable development of a hybrid nanoparticle carrying VEGF siRNA, as well as their tumor targeting, accumulation and reduction in mice triple-negative breast cancer.     

Immunologic-mediated Protection of Trypanosoma congolense-Infected Mice by Polyribonucleotides

SYNOPSIS. When the synthetic polyribonucleotides polyinosinic acid-polycytidylic acid (poly I poly C) and polyadenylic acid-polyuridylic acid (poly A poly U) were tested against mice infected with varying numbers of Trypanosoma congolense the results varied with the method of passage of trypanosomes in mice. Thus, when 100 flagellates were passaged every 7th day and experiments were initiated with these trypanosomes from mice on the 7th day of their infection, the protective effects of poly I poly C and poly A poly U apparently varied independently of each other as assayed by the mean parasitemias and cumulative mortalities of infected mice. Poly I poly C-resistant and poly I poly C-susceptible variants (“R” and “S”, respectively) were isolated and maintained in mice by passage of 10⁶ trypanosomes every 4th day. Mice infected with these variants responded consistently to poly I poly C and poly A poly U injections in that mice infected with the “R” variant showed no response to either polyribonucleotide but those infected with the “S” variant consistently had a decrease in mean parasitemias and cumulative mortality when treated with poly I poly C, but not with poly A poly U. Using mice infected with the “S” variant, the protective effect of poly I poly C was dose-dependent and best protection was afforded when 1st injections of poly I poly C were given around the time of infection of the mice. The protective effects of the synthetic polyribonucleotides used in these experiments are probably due to their immunologic enhancing capacities and not to interferon. To support this, injections of Newcastle disease virus, a strong inducer of interferon in mice, did not protect against T. congolense in mice. It was not possible to determine whether serum from poly I poly C-treated mice had a greater neutralizing effect upon trypanosomes in vitro than serum from saline-treated mice since any effect of antibody was masked by a naturally occurring inhibitor in normal mouse serum which was reduced during infection. The protective effects of poly I poly C in T. congolense-infected mice were reversed by treatment with cyclophosphamide. This strong immunosuppressant, however, could not reverse the protective effects of poly I poly C against mice infected with Semliki Forest virus, strongly suggesting that the protective mechanisms stimulated by poly I poly C in these 2 infections were different. The response of mice infected with the “R” and “S” variants of T. congolense to synthetic polyribonucleotides is discussed in relation to antigenic variation of trypanosomes.     

Cell-free translation of messenger RNA from oocytes of Xenopus laevis

The poly(A)⁺ RNA which accumulates during oogenesis in the amphibian Xenopus laevis is shown to be functional mRNA; the RNA was active in the mRNA-dependent “shift assay” for initiation sites in the rabbit reticulocyte lysate, and was an efficient template for protein synthesis in the wheat-germ cell-free system. Analysis of the in vitro protein products showed no differences between the coding properties of poly(A)⁺ RNA extracted from oocytes at all stages of development from previtellogenesis to maturity. In previtellogenic oocytes, the in vitro products of polysomal and of mRNP-associated poly(A)⁺ RNA were also identical. Neither was there any evidence for changes in the coding properties of the poly(A)⁺ mRNA of the oocyte. However, the patterns of oocyte in vivo protein synthesis changed markedly during early vitellogenesis. We conclude that the mRNP-associated poly(A)⁺ RNA present in mature oocytes constitutes the stored maternal mRNA, and that during oogenesis the coding composition of the poly(A)⁺ mRNA synthesised does not change markedly, while some form of translational control operates to direct the changing pattern of protein synthesis.