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At least 19 recordsLinked to original sources
PubMed1978

Double stranded RNA in heterogeneous nuclear RNA from normal and chronic lymphocytic leukemic lymphocytes.

Tritium labelled heterogeneous nuclear RNA (HnRNA) from normal and chronic lymphocytic leukemic (CLL) lymphocytes was investigated before and after fractionation into non-poly(A) containing (-HnRNA) and poly(A) containing (+HnRNA) HnRNA with respect to double stranded RNA (dsRNA). Statistically significant higher amounts of rapidly labelled RNA were recovered from CLL lymphocytes when compared to normal cases. Within the CLL cases a significant linear correlation (r = 0.95) was found between white blood cell counts and the amount of dsRNA in total HnRNA. After fractionation into (-) and (+) HnRNAs the ratios of dsRNAs, expressed as the dsRNA in (-) HnRNA divided by the dsRNA in (+) HnRNA, was lower than the corresponding values in normal cases for all the CLL cases except one. The relationship between (+) HnRNA and the total dsRNA level was different when comparing CLL and normal lymphocytes indicating a RNA processing abnormality.

Humans↗
PubMed1971

Hybridization properties of DNA sequences directing the synthesis of messenger RNA and heterogeneous nuclear RNA.

The relationship of the DNA sequences from which polyribosomal messenger RNA (mRNA) and heterogeneous nuclear RNA (NRNA) of mouse L cells are transcribed was investigated by means of hybridization kinetics and thermal denaturation of the hybrids. Hybridization was performed in formamide solutions at DNA excess. Under these conditions most of the hybridizing mRNA and NRNA react at values of D(o)t (DNA concentration multiplied by time) expected for RNA transcribed from the nonrepeated or rarely repeated fraction of the genome. However, a fraction of both mRNA and NRNA hybridize at values of D(o)t about 10,000 times lower, and therefore must be transcribed from highly redundant DNA sequences. The fraction of NRNA hybridizing to highly repeated sequences is about 1.7 times greater than the corresponding fraction of mRNA. The hybrids formed by the rapidly reacting fractions of both NRNA and mRNA melt over a narrow temperature range with a midpoint about 11 degrees C below that of native L cell DNA. This indicates that these hybrids consist of partially complementary sequences with approximately 11% mismatching of bases. Hybrids formed by the slowly reacting fraction of NRNA melt within 4 degrees -6 degrees C of native DNA, indicating very little, if any, mismatching of bases. Hybrids of the slowly reacting components of mRNA, formed under conditions of sufficiently low RNA input, have a high thermal stability, similar to that observed for hybrids of the slowly reacting NRNA component. However, when higher inputs of mRNA are used, hybrids are formed which have a strikingly lower thermal stability. This observation can be explained by assuming that there is sufficient similarity among the relatively rare DNA sequences coding for mRNA so that under hybridization conditions, in which these DNA sequences are not truly in excess, reversible hybrids exhibiting a considerable amount of mispairing are formed. The fact that a comparable phenomenon has not been observed for NRNA may mean that there is less similarity among the relatively rare DNA sequences coding for NRNA than there is among the rare sequences coding for mRNA.

Animals↗
PubMed1970

Messenger and heterogeneous nuclear RNA in HeLa cells: differential inhibition by cordycepin.

Cordycepin (3'-deoxyadenosine) suppresses the labeling of messenger RNA in HeLa cells. The drug has no effect on either the labeling of nuclear heterogeneous RNA or on the transport of messenger RNA into the cytoplasm. The results suggest that messenger RNA and nuclear heterogeneous RNA are synthesized separately, and that the transcription of messenger RNA is inhibited by the drug.

Carbon Isotopes↗
PubMed1975

Identification of human RNA transcripts among heterogeneous nuclear RNA from man-mouse somatic cell hybrids.

In man-mouse hybrid line from our cell library, the only cytological detectable portion of the human genome is the X chromosome, and the only genetic markers regularly expressed are coded by genes known to be ?X-linked. A component of the heterogeneous nuclear RNA of these cells was found to be complementary to repetitive human DNA sequences by means of RNA-DNA hybridization on nitrocellulose filters. The same procedure also permitted the identification of hybrid cell DNA sequences that are complementary to human heterogeneous nuclear RNA. This experimental approach, coupled with hybridization studies in situ, is expected to yield critical data on the distribution and the specificity of the repetitive DNA sequences present in the human genome and to provide a new tool for cytological mapping of human chromosomes.

Animals↗
PubMed1972

Double-stranded regions in heterogeneous nuclear RNA from Hela cells.

Heterogeneous nuclear RNA from HeLa cells contains double-stranded regions that arise by base pairing of complementary sequences that exist as parts of the same molecule (intramolecular base pairing). When denatured, the RNA sequences that form the double-stranded regions hybridize rapidly to HeLa cell DNA, suggesting that they are transcribed from reiterated sites in the genome. The messenger RNA does not contain the same class or amount of double-stranded RNA regions found in heterogeneous nuclear RNA.

Cell Nucleus↗
PubMedDate not supplied

[Metabolically stable classes of messenger-like nuclear RNA. II. Existence of homology between the 28S fraction of nuclear RNA, giant non-polyadenylated molecules of heterogeneous nuclear RNA and polyadenylated molecules of cytoplasmic RNA].

The existence and extent of homology between the 28S fraction of messenger-like nuclear RNA on one hand, and giant (greater than 45S) molecules of heterogeneous nuclear RNA and various fractions of cytoplasmic RNA on the other hand were studied by the method of competitive hybridization. The results obtained lead to the conclusion that the poly(A)-subfraction of hnRNA molecules with the size of greater than 15 000 nucleotides contains molecules subjected to rapid but incomplete processing with the formation of chains approximately 5000 nucleotides long (approximately 28S), which are then stored in the nucleus for up to 30 hours. Later polyadenylated and non-polyadenylated molecules of cytoplasmic RNA with the size of less than or equal to 2000 nucleotides are formed from the stored precursors.

Animals↗
PubMed1972

Occurrence of uridylate-rich oligonucleotide regions in heterogeneous nuclear RNA of HeLa cells.

Heterogeneous nuclear RNA molecules from HeLa cells contain a specific segment of about 30 nucleotides length that is largely (about 80%) uridylic acid. This oligo(U) segment is located predominantly in the larger (70S-90S) heterogeneous nuclear RNA molecules, and is essentially absent in messenger RNA and 45S ribosomal precursor RNA molecules. The oligo(U) hybridizes rapidly to cellular DNA, suggesting that it is transcribed from the repeated regions of the DNA.

Alkaline Phosphatase↗
PubMed1977

The heterogeneous nuclear RNA of chicken erythroblasts.

Heterogeneous nuclear RNA (hnRNA) from chicken erythroblasts has a modal molecular weight of 1.6 -10(6) in 99% dimethylsulfoxide. When erythroblasts are labeled continuously with [14C]uridine, nuclear RNA is labeled as a single kinetic component with a half-life of 18 min. After a 10--20 min lag, label appears in cytoplasmic RNA at about 1% of the initial rate of total RNA synthesis. Of the hnRNA sedimenting faster than 28 S ribosomal RNA in both an aqueous sucrose gradient and a subsequent fructose gradient in 99% dimethylsulfoxide, about one-third is polyadenylated, although only about one in 2000 (i.e. about four molecules per cell) contain a globin messenger sequence. The hnRNA of erythroblasts isolated from 5.7- and 11-day chick embryos have the same content of globin messenger sequences as erythroblaasts from anemic adults.

Anemia↗
PubMed1977

Oligouridylate stretches in heterogeneous nuclear RNA.

Three classes of heterogeneous nuclear RNA (HnRNA) alpha, beta, and gamma, with different chemical and physical properties, can be identified in the early sea urchin embryo by hybridization with poly(U). The relative amounts of these classes vary as a function of embryonic development. It is demonstrated here that the adenyl-containing classes of HnRNA, alpha and beta, can be subfractionated by hybridization with poly(A)-agarose into species containing and lacking oligo(U)-enriched segments. These oligo(U) segments could not be detected in gamma HnRNA, which was previously shown to also lack adenylate segments. The relative proportions of these species undergo marked changes during development from early blastula (7 hr) to mesenchyme blastula (20 hr). I propose models to explain the possible effects of complementary sequences of adenylate and uridylate on the secondary structure of HnRNA, and speculate on the functional significance of such complexes.

Animals↗
PubMed1979

Effect of 5-bromodeoxyuridine on heterogeneous nuclear RNA in rat hepatoma cells.

Heterogeneous nuclear RNA HnRNA) was isolated from untreated and 5-bromodeoxyuridine (BrdUrd) treated hepatoma tissue culture (HTC) cells. analysis of this RNA by either electrophoresis on polyacrylamide-agarose gels or centrifugation in sucrose gradients demonstrated that BrdUrd caused a shift in the labeled HnRNA population toward a smaller size distribution. This effect was produced by concentrations of BrdUrd which specifically lower the level of the differentiated enzyme tyrosine aminotransferase, but do not greatly affect cell growth. Differential binding to oligo(dT) cellulose was used to fractionate HnRNA further into classes containing poly(A) (alpha), oligo(A) (beta) or neither category of A-rich sequences (gamma). BrdUrd did not alter the relative rates of uridine incorporation into the three classes. The shift in the labeled HnRNA population due to BrdUrd was observed in all three subclasses of HnRNA.

Animals↗
PubMed1970

A comparison between heterogeneous nuclear RNA and polysomal messenger RNA in HeLa cells by RNA-DNA hybridization.

Heterogeneous nuclear RNA (HnRNA) and mRNA from cytoplasmic polyribosomes of HeLa cells have been compared by RNA-DNA hybridization tests. 1 microg of HeLa cell DNA binds 0.05-0.10 microg of either HnRNA or mRNA. In addition, HeLa DNA that is preexposed to unlabeled HnRNA was found to have a reduced capacity to bind either HnRNA or mRNA. The results are compatible with considerable sequence similarity in the two types of RNA but, as is discussed, firm conclusions are precluded by imperfections of the hybridization reaction as presently employed.

Cell Nucleus↗
PubMedDate not supplied

Heterogeneous nuclear RNA from hairy cell leukemia patients activates 2',5'-oligoadenylate synthetase.

Interferon treatment of cells induces double-stranded RNA (dsRNA)-dependent 2',5' oligoadenylate (2-5A) synthetase, an enzyme which has been implicated in the mechanism of growth arrest in tumour cells. Since interferon (IFN) can inhibit the growth of cells that are not infected with virus, natural non-viral dsRNAs should be present in these cells which can activate 2-5A synthetase. If such nuclear dsRNAs are associated with the mechanism of growth control, cells inherently sensitive to growth inhibition by IFN should contain significant levels of 2-5A synthetase-activating dsRNAs. We measured the ability of size fractionated nuclear dsRNAs isolated from patients with hairy cell leukemia (HCL) to activate purified 2-5A synthetase. Peripheral blood mononuclear cells from HCL patients were utilized because of the inherent sensitivity of these patients to IFN treatment. The heterogeneous nuclear RNA fraction from four out of five HCL patients showed high levels of 2-5A synthetase-activating dsRNAs. The 2-5A formed contained biologically active trimers, tetramers, pentamers and hexamers as demonstrated by HPLC analysis and their ability to activate RNase L. In contrast, the nuclear RNA fraction from three out of four healthy controls were unable to activate 2-5A synthetase. These results indicate that natural, nuclear dsRNAs inherently exist in IFN-sensitive cells and imply that these molecules may play a role in the inhibition of cellular growth.

2',5'-Oligoadenylate Synthetase↗
PubMed1977

Heterogeneous nuclear RNA secondary structure: oligo (U) sequences base-paired with poly (A) and their possible role as binding sites for heterogeneous nuclear RNA-specific proteins.

HeLa cell heterogeneous nuclear RNA derived from high-molecular-weight nuclear ribonucleoprotein (RNP) particles contains oligo(U) sequences of 15-50 nucleotides base-paired with poly(A). These duplexes are resistant to pancreatic RNase at 0.5 M NaCl in native RNP, remain so after chemical deproteinization of the RNP digests, and then copurify with poly(A) on oligo(dT)-cellulose chromatography. Oligo(dT)-cellulose binding capacity of the oligo(U)-poly(A) duplexes is abolished by prior titration of the nonduplex poly(A) regions with excess poly(U). The oligo(dT)-purified fraction is 97.5 mole % A + U and the [3H]uridine-labeled component is resistant to redigestion by pancreatic RNase at 0.5 M NaCl but not at 0.01 M NaCl. After thermal denaturation, the [3H]uridine-labeled chains become RNase-sensitive at 0.5 M NaCl. Electrophoresis of [3H]adenosine- or [3H]uridine-labeled material in polyacrylamide gels containing 99% formamide confirms that the oligo(U) sequences are not covalently linked to poly(A). Controls establish that the A-U duplexes are not formed artifactually during isolation of heterogeneous nuclear RNP or subsequent fractionation. The oligo(U)-poly(A) duplexes appear to be associated with protein in native heterogeneous nuclear RNP, as reflected by the differential pancreatic RNase sensitivity of the duplexed oligo(U) in RNP (resistant) and RNA (sensitive), measured at physiological ionic strength.

Base Sequence↗