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At least 109 records · Page 6Linked to original sources
PubMed1984

[Characterization of total RNA, messenger poly(A)+ RNA and homologous complementary DNA in experimental cardiac hypertrophy].

Two biological modifications are observed during adaptation of cardiac tissue to work overload: an increase in total protein synthesis and a redistribution of myosin isoenzymes. These modifications suggest that changes in DNA transcription are involved in the early response of cardiac tissue to overload. Results are reported in this paper that show a parallel increase in total and polyadenylated RNA content and concentration in cardiac overloaded tissue in the rat. The characterization of cardiac poly (A)+ mRNA by mRNA X cDNA hybridization and the identification of specific mRNAs with recombinant plasmid cDNAs are given in this report as preliminary results.

Animals↗
PubMed2000

Loss of alternately spliced messenger RNA of the luteinizing hormone receptor and stability of the follicle-stimulating hormone receptor messenger RNA in granulosa cell tumors of the human ovary.

OBJECTIVES: The expression of messenger RNA (mRNA) for the LH (LHR) and FSH receptors (FSHR) was examined in normal human corpora lutea and granulosa cell tumors. METHODS: Expression was examined by RT/PCR and DNA sequencing techniques. RESULTS: The full-length (FL) coding region and seven additional isoforms were identified for normal LHR mRNA. Isoform 1 had portions of exons II and III deleted, and isoform 2 had exon IX omitted. Isoform 3 also had portions of exons II and III deleted and all of exon IX deleted. Exons III through VI were missing in isoforms 4-7. Isoform 5 also had exon IX omitted, and isoform 6 also had part of exon XI missing. Isoform 7 also had exon IX and part of exon XI deleted. An aberrant migration pattern of the LHR mRNA isoforms was observed for granulosa cell tumors with FIGO Stage I-IV. Five tumor samples of Stage III-IV had many isoforms absent. Seven Stage I samples had aberrant migration patterns that depended on the size of the tumor. As the size of the tumor increased the aberrant migration pattern of the LHR mRNA isoforms was more pronounced and some isoforms were not detected. The FL and at least one additional isoform were identified for FSHR mRNA. Isoform 1 had regions of exons IV and V deleted. The FSHR mRNA isoforms had a similar migration pattern for the normal ovary and the granulosa cell tumors. CONCLUSIONS: Alternately spliced forms of mRNA for the LHR and FSHR exist for normal human ovary and granulosa cell tumors. The aberrant migration and missing LHR mRNA isoforms in granulosa cell tumors do not appear to result from general genomic instability associated with tumor progression. These findings are important to understand the role of alternate splicing in the regulation of LHR and FSHR expression in different pathological states.

Alternative Splicing↗
PubMed1980

Messenger RNA processing and nuclear structure: isolation of nuclear ribonucleoprotein particles containing beta-globin messenger RNA precursors.

To explore the relationships between transcription, messenger RNA (mRNA) processing, and nuclear structure, ribonucleoprotein particles containing heterogeneous nuclear RNA (hnRNP) have been purified from globin-producing mouse Friend erythroleukemia cells. These nuclear hnRNP particles sediment at 50S-200S and contain, in addition to high molecular weight hnRNA, a specific set of nuclear proteins predominated by a major component of approximately 38,000 mol wt. The hnRNP particles are free of histones and ribosomal structural proteins, indicating their purification from the two other major nucleoprotein components of the nucleus: chromatin and nucleolar ribosomal precursor RNP particles. Th authenticity of the Friend cell hnRNP particles is demonstrated by the results of reconstruction experiments with deproteinized hnRNA, and by the resistance of the articles to dissociation during isopycnic banding in Cs2SO4 gradients without prior aldehyde fixation. Hybridization analysis with cloned mouse beta-globin DNA demonstrates that hnRNP particles from induced Friend cells contain newly synthesized transcripts of the beta-globin gene. Agarose gel electrophoresis of hnRNP particle-derived RNA denatured in glyoxal followed by "Northern" transfer to diazobenzyloxymethyl paper and hybridization with 32P-labeled cloned mouse beta-globin DNA reveals the presence in hnRNP of two size classes of beta-globin gene transcripts, the larger of which corresponds to the pre-spliced 15S beta-globin mRNA precursor previously identified in whole nuclear RNA, and the smaller of which corresponds to completely processed 9S beta-globin mRNA. These results establish, for the first time, that the nuclear transcripts of a specific, well-defined eukaryotic structural gene can be isolated in an RNP particle form, and that their RNP structure persists throughout mRNA splicing.

Animals↗
PubMed1976

Rates of synthesis of polyadenylated messenger RNA and ribosomal RNA during the cell cycle of Schizosaccharomyces pombe. With an appendix: calculation of the pattern of protein accumulation from observed changes in the rate of messenger RNA synthesis.

The rates of polyadenylated messenger RNA and ribosomal RNA synthesis were measured in synchronously dividing cultures of fission yeast (Schizosaccharomyces pombe). Control asynchronous cultures, which had been exposed to the conditions used for preparing synchronous cultures, were investigated to check for effects of the synchronization procedure itself on RNA synthesis. After each period of DNA synthesis in synchronous culture, the rates of messenger and ribosomal RNA synthesis doubled, suggesting that gene number controls the rate of messenger and ribosomal RNA synthesis. This was confirmed by experiments with asynchronous, exponential-phase cultures in which DNA synthesis was inhibited by hydroxyurea. Both synchronous culture and hydroxyurea experiments suggested that there is a delay of 15 min (0-1 of the cell generation time) between replication of the DNA and transcription of both gene copies. A pattern of protein accumulation was calculated from changes in the rate of polyadenylated messenger RNA synthesis during synchronous culture. The simulated pattern indicates that protein is accumulated linearly, with a doubling in the rate of accumulation once per cell cycle. The simulated pattern of protein accumulation is very similar to measurements previously reported by other workers of changes in activities of 3 enzymes in synchronous cultures. It is suggested that the doubling of the rate of messenger RNA synthesis, as a consequence of the replication of the DNA once per cycle, provides the basis of a mechanism for control of the doubling of other cellular constituents during the cell cycle.

Adenine↗
PubMed1997

A conformational switch in Escherichia coli 16S ribosomal RNA during decoding of messenger RNA.

Direct evidence is presented for a conformational switch in 16S ribosomal RNA (rRNA) that affects tRNA binding to the ribosome and decoding of messenger RNA (mRNA). These data support the hypothesis that dynamic changes in rRNA structure occur during translation. The switch involves two alternating base-paired arrangements apparently facilitated by ribosomal proteins S5 and S12, and produces significant changes in the rRNA structure. Chemical probing shows reciprocal enhancements or protections at sites in 16S rRNA that are at or very near sites that were previously crosslinked to mRNA. These data indicate that the switch affects codon-anticodon arrangement and proper selection of tRNA at the ribosomal A site, and that the switch is a fundamental mechanism in all ribosomes.

Anticodon↗
PubMed1970

Isolation of RNA with properties of messenger RNA from cerebral polyribosomes.

RNA which dissociated from purified cerebral polyribosomes of adult rats in the presence of EDTA was isolated by fractionation in a discontinuous sucrose gradient. The yield was 2% of the total polyribosomal RNA. The base composition resembled the complementary values for rat DNA and was very different from base compositions of ribosomal RNA and transfer RNA. This RNA fraction contained a large proportion of molecules which were rapidly labeled in vivo and hybridized to homologous DNA. The polyribosomal RNA preparation also exhibited high template activity in a cerebral cell-free system which had previously been stripped of the capacity to incorporate amino acids in the absence of added messenger RNA (mRNA). Sedimentation analysis revealed only two peaks, with coefficients of approximately 8 S and 16 S. The data indicate that RNA with the properties of mRNA can be selectively isolated from cerebral polyribosomes under mild conditions which avoid degradation.

Animals↗
PubMed1980

Changes in RNA synthesis and messenger RNA content in the cerebellum of rats with graft versus host disease.

Cerebellar RNA accumulation, synthesis, and functional capacity was studied in 14-day-old F1 hybrid rats subjected to neonatally induced graft versus host disease (GVHD). There was a decrease in RNA synthetic rate as measured by the uptake of labeled precursors into RNA. The decrease in total cerebellar RNA synthesis was reflected both in a reduced amount of Nissl substance, visible in cresyl violet-stained 10-micron-thick sections of cerebella, and in the total amount of cytoplasmic RNA isolated from individual cerebella from diseased animals compared with control littermates. Analysis of the RNA translational capacity in wheat germ protein synthesizing systems showed that RNA from experimental animals was also biologically less active. Qualitative differences between protein populations in control and diseased animals were analyzed by two-dimensional gel electrophoresis. There were few alterations in the steady state levels of cerebellar protein. However, two-dimensional gel electrophoresis of the peptides synthesized in vitro by RNA from control and diseased animals showed that there were several changes in the relative abundance of some mRNAs between the two RNA populations. These data show that the cerebellar RNA from rats with GVHD differs both qualitatively and quantitatively from that of controls.

Animals↗
PubMed2001

Transfer RNA(Ala) recognizes transfer-messenger RNA with specificity; a functional complex prior to entering the ribosome?

tmRNA (SsrA or 10Sa RNA) functions as both a transfer RNA and a messenger RNA, rescues stalled ribosomes and clears the cell of incomplete polypeptides. We report that native Escherichia coli tmRNA interacts specifically with native or synthetic E.coli tRNA alanine (tRNA(Ala)) in vitro, alanine being the first codon of the tmRNA internal open reading frame. Aminoacylatable RNA microhelices also bind tmRNA. Complex formation was monitored by gel retardation assays combined with structural probes. Nucleotides from the acceptor stem of tRNA(Ala) are essential for complex formation with tmRNA. tRNA(Ala) isoacceptors recognize tmRNA with different affinities, with an important contribution from tRNA(Ala) post-transcriptional modifications. The most abundant tRNA(Ala) isoacceptor in vivo binds tmRNA with the highest affinity. A complex between tRNA(Ala) and tmRNA might involve up to 140 tmRNA molecules out of 500 present per E.coli cell. Our data suggest that tmRNA interacts with the tRNA that decodes the resume codon prior to entering the ribosome. Biological implications of promoting specific complexes between tmRNA and aminoacylatable RNAs are discussed, with emphasis on primitive versions of the translation apparatus.

Base Sequence↗
PubMedDate not supplied

Quantitative analysis of rat thyroglobulin messenger RNA in FRTL-5 cells by competitive polymerase chain reaction with human thyroglobulin messenger RNA.

To measure relative expression level of mRNA in a small number of cultured rat thyroid cells (FRTL-5), we developed a system of a quantitative reverse transcription-polymerase chain reaction (RT-PCR) assay. Human thyroglobulin mRNA in total RNA extracted from a human thyroid tissue was used as an internal control. FRTL-5 cells in a 24 well dish were lysed with denaturing solution containing human RNA. Total RNA was extracted followed by reverse transcription and polymerase chain reaction. After digestion with a restriction enzyme, PCR products were separated by electrophoresis and stained with Sybr Green I, then their fluorescence was measured with fluorescent image analyser. Increase of thyroglobulin mRNA in FRTL-5 cells stimulated by thyroid stimulating hormone (TSH) was observed by this technique. Because this method does not require a large number of cells or radioactive isotopes, it is as useful for the analysis of the relative expression level of mRNAs in the cells as the conservative methods such as Northern Blot.

Animals↗
PubMed1984

Relationship between the transport from isolated nuclei of two abundant cytoplasmic messengers and the source of a messenger RNA transport factor.

Messenger RNA transport from isolated nuclei requires a 35 X 10(3) dalton cytoplasmic protein(s) which is present in both the cytosol and polyribosome fractions. Recombinant DNA probes containing cDNA inserts were used to quantitate the transport of rat liver-specific albumin and male rat liver-specific alpha 2U-globulin messenger RNA (mRNA) from male rat liver nuclei in response to the mRNA transport factors from homologous and heterologous tissues. No mRNA transport occurs in the absence of the transport factor(s). Both messengers are transported proportionately in response to the factor(s) from male or female rat liver cytosol, or from the polyribosomes (messenger ribonucleoprotein) of male or female rat liver, or brain. The transport factor(s) do not, therefore, appear to differentiate between the coding sequences of two unrelated hepatic messenger RNA's.

Albumins↗
PubMed1999

Induction of cyclooxygenase-2 messenger RNA after transient and permanent middle cerebral artery occlusion in rats: comparison with c-fos messenger RNA by using in situ hybridization.

OBJECT: Recently, two different cyclooxygenase (COX) genes, COX-1 and -2, were identified. In this study, topographic and chronological profiles of COX-2 messenger (m)RNA and c-fos mRNA expression were investigated using in situ hybridization after focal cerebral ischemia. METHODS: Rats undergoing permanent ischemia were decapitated at 30 and 90 minutes and at 2, 4, 8, and 24 hours after middle cerebral artery (MCA) occlusion, and rats undergoing transient ischemia were decapitated at 4, 8, and 24 hours after MCA occlusion that lasted for either 30 or 90 minutes. After brief transient MCA occlusion, c-fos mRNA was induced in the whole MCA territory, adjacent cortex (cingulate cortex), and distant brain regions such as the hippocampus and substantia nigra. In contrast, COX-2 mRNA was not induced in the ischemic core (lateral striatum) but only in the penumbral area (MCA cortex). Long transient and permanent MCA occlusion did not induce c-fos and COX-2 mRNAs in the ischemic core but strongly induced both mRNAs in the penumbral area (medial striatum and periphery of MCA cortex) and adjacent cortex (cingulate cortex). In brain regions distant from the ischemic territory, although c-fos mRNA was induced in the thalamus, substantia nigra, and hippocampus after extended transient and permanent occlusion, COX-2 mRNA was only induced in the bilateral hippocampi. The induction of COX-2 mRNA persisted in all locations even at 24 hours after MCA occlusion. CONCLUSIONS: The distribution of COX-2 mRNA induction was apparently different from that of c-fos mRNA after MCA occlusion. These results pertaining to COX-2 mRNA agree well with the previous observations of changes in prostaglandin metabolism induced by focal cerebral ischemia. However, whether this induction of the COX-2 gene contributes to the histopathological outcome of cerebral ischemia remains to be elucidated.

Animals↗