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At least 757 records · Page 42Linked to original sources
PubMed1997

Amygdala kindling alters N-methyl-D-aspartate receptor subunit messenger RNA expression in the rat supraoptic nucleus.

Intense electrical activity throughout the brain which results from generalized epileptic or kindled seizures is thought to cause persistent and widespread neuronal plastic changes. We have previously reported that stage 5 kindled seizures cause an increase in vasopressin messenger RNA content and nitric oxide synthase activity in neuroendocrine cells of the supraoptic nucleus which lasts for at least four months after the last seizure. To evaluate whether changes in the expression of N-methyl-D-aspartate receptor subunits might contribute to these effects, the expression of NR1, NR2A, NR2B. NR2C and NR2D subunit messenger RNAs was examined by in situ hybridization in neuroendocrine cells of the supraoptic nucleus one month after amygdala kindling to stage 5 seizures. No change in NR1 subunit messenger RNA expression was seen. In contrast, NR2B subunit messenger RNA was significantly increased. by about 63%, and NR2D subunit messenger RNA was significantly decreased, by about 22%. indicating a shift in NR2 subunit messenger RNA expression. NR2B subunit messenger RNA was also significantly increased in adjacent limbic structures. The long-lasting shift towards increased NR2B and decreased NR2D messenger RNA expression after kindling suggests that N-methyl-D-aspartate receptor NR2 composition may be an important factor in the maintenance of pathological plasticity following generalized seizures. If these changes in messenger RNA are translated into increased NR2B and decreased NR2D subunits in the N-methyl-D-aspartate receptors in vivo, both a decrease in sensitivity due to a strong magnesium block and an increase in channel ion gating might be predicted.

Amygdala↗
PubMed1983

Voltage-operated channels induced by foreign messenger RNA in Xenopus oocytes.

Poly(A)+ messenger RNA (mRNA) extracted from rat brains or from cat muscles was injected into Xenopus laevis oocytes. This led to the incorporation of voltage-operated Na+ and K+ channels into the oocyte membrane. These channels are not normally present in the oocyte and presumably result from the synthesis and processing of proteins coded by the injected mRNA. Tetrodotoxin blocked the Na+ channels induced by mRNA derived from either innervated or denervated muscle.

Animals↗
PubMed1981

The preparation of biologically active messenger RNA from human postmortem brain tissue.

Messenger RNA (mRNA) was extracted from human postmortem brain tissue by alkaline phenol extraction of polysomes followed by oligo (dT)-cellulose chromatography. The mRNA preparations stimulated protein synthesis in a cell-free system containing wheat germ homogenate. The products of protein synthesis were analyzed by one- and two-dimensional gel electrophoresis. These analyses indicated that numerous polypeptides, including tubulin subunits and actin isomers, were synthesized by the human mRNA. The molecular weight range of polypeptides synthesized by human mRNA fractions from two brain specimens were identical, and analysis by two-dimensional gel electrophoresis indicated qualitatively similar products. The yield of mRNA extracted per gram of human tissue was less than the yield obtained with rat forebrains from animals sacrificed immediately before brain removal and mRNA purification. A decrease in the amount of polysomes isolated from human tissue relative to rat brain tissue was a major factor contributing to the low yield. The molecular weight distribution of polypeptides synthesized by human and rat brain mRNA fractions in wheat germ homogenate was similar; thus, there was no indication for selective breakdown or inactivation of high molecular weight mRNA species in the human tissue. Our studies indicate that it is possible to utilize postmortem tissue for molecular biological investigations of human brain mRNA.

Animals↗
PubMed1966

Gene-specific messenger RNA: isolation by the deletion method.

Messenger RNA molecules, homologous to a small portion of the genome of bacteriophage T4, have been isolated. RNA fragments specific to the rII A and the rII B cistrons have been separated by hybridization with DNA isolated from appropriate deletion mutants. An RNA species homologous in nucleotide sequence to a defined part of the rII A cistron has been identified.

Coliphages↗
PubMed1988

An in vitro system for accurate methylation of internal adenosine residues in messenger RNA.

Some internal adenosine residues in messenger RNA are methylated posttranscriptionally in the nucleus. Most of the methylated adenosine residues in prolactin mRNA are in the 3' untranslated region. The site of methylation in the 3' end of prolactin mRNA was determined. This methylation reaction is highly specific; of the three adenosine residues in consensus sequences located in the 3' end, only one is methylated. An in vitro methylation system was developed in which bovine prolactin mRNA, synthesized in vitro with T7 RNA polymerase, was accurately methylated in a HeLa cell nuclear extract. The adenosine residue that was methylated in vitro was the same as the one methylated in vivo. This cell-free system, which accurately methylates the N6-position of adenosine residues in mRNA, will allow further study of the mechanism of adenosine methylation.

Adenosine↗
PubMed2004

Estrogen receptor-alpha messenger RNA variants that lack exon 5 or exon 7 are coexpressed with wild-type form in human endometrium during all phases of the menstrual cycle.

OBJECTIVE: We have assessed the expression levels of messenger RNA for estrogen receptor-alpha and splice variants lacking exon 5 or exon 7 that presumably exert dominant positive (splice variants lacking exon 5) and negative (splice variants lacking exon 7) effects, respectively, on estrogen responses in the human endometrium. STUDY DESIGN: This was a prospective study that was conducted at an academic community-based hospital. The patients, aged 18 to 40 years, underwent hysterectomy for benign gynecologic causes. Eighty-one endometrial specimens (46 proliferative, 35 secretory) were analyzed with the use of reverse transcription-polymerase chain reaction assay for the messenger RNA levels of estrogen receptor-alpha, and splice variants lacking exon 5 and exon 7. RESULTS: Wild-type estrogen receptor-alpha and splice variants splice variants lacking exon 5 and lacking exon 7 messenger RNAs were detected in all endometrial specimens throughout the menstrual cycle. In addition, a double-splice estrogen receptor-alpha messenger RNA variant (splice variants lacking exon 5 and exon 7) was detected at constant low levels of expression. Semiquantitative analysis showed higher levels of estrogen receptor-alpha messenger RNA in the early and mid proliferative endometrial phases than in late proliferative and secretory endometrium ( P <.05). The splice variant lacking exon 7 messenger RNA expression level was about 10-fold higher than the splice variant lacking exon 5 messenger RNA relative to wild-type estrogen receptor-alpha messenger RNA ( P <.001). The expression of splice variants lacking exon 5 compared with wild-type estrogen receptor-alpha messenger RNA is relatively constant throughout endometrial development. In contrast, an examination of the ratio of the levels of splice variants lacking exon 7 to wild-type estrogen receptor-alpha messenger RNA indicated a small, but significantly higher, splice variant lacking exon 7 level in the mid secretory phase (postovulatory days 5-8) than the mid proliferative and early secretory phases ( P <.05). CONCLUSION: We found no evidence of differential coexpression of the positive dominant estrogen receptor variant, splice variants lacking exon 5, with wild-type estrogen receptor-alpha. We did find that the dominant negative splice variant lacking exon 7 was slightly increased relative to wild-type estrogen receptor-alpha in the postovulatory phase. Future investigation is required to suggest the biologic significance of the observed increased relative expression of the splice variants lacking exon 7 in secretory endometrium and to determine the function of splice variants lacking exon 5 and splice variants lacking exon 7.

Alternative Splicing↗
PubMed1987

Splicing of messenger RNA precursors.

A general mechanism for the splicing of nuclear messenger RNA precursors in eukaryotic cells has been widely accepted. This mechanism, which generates lariat RNAs possessing a branch site, seems related to the RNA-catalyzed reactions of self-splicing introns. The splicing of nuclear messenger RNA precursors involves the formation of a multicomponent complex, the spliceosome. This splicing body contains at least three different small nuclear ribonucleoprotein particles (snRNPs), U2, U5, and U4 + U6. A complex containing precursor RNA and the U2 snRNP particle is a likely intermediate in the formation of the spliceosome.

Animals↗
PubMed1992

The end of the message: 3'-end processing leading to polyadenylated messenger RNA.

Almost all messenger RNAs carry a polyadenylate tail that is added in a post-transcriptional reaction. In the nuclei of animal cells, the 3'-end of the RNA is formed by endonucleolytic cleavage of the primary transcript at the site of poly(A) addition, followed by the polymerisation of the tail. The reaction depends on specific RNA sequences upstream as well as downstream of the polyadenylation site. Cleavage and polyadenylation can be uncoupled in vitro. Polyadenylation is carried out by poly(A) polymerase with the aid of a specificity factor that binds the polyadenylation signal AAUAAA. Several additional factors are required for the initial cleavage. A newly discovered poly(A)-binding protein stimulates poly(A) tail synthesis and may be involved in the control of tail length. Polyadenylation reactions different from this scheme, either in other organisms or under special physiological circumstances, are discussed.

Animals↗
PubMed1991

A study on postmortem stability of vasopressin messenger RNA in rat brain compared with those in total RNA and ribosomal RNA.

Postmortem stability of arginine-vasopressin (AVP) messenger RNA (mRNA) in the rat brain was studied comparing changes with those in the recovered amounts of total RNA and ribosomal RNA (rRNA). The amount of AVP mRNA and rRNA showed a decrease with increasing time interval after death (postmortem time), whereas the amount of total RNA did not alter with postmortem time. The half-life of AVP mRNA in the rat postmortem seemed to be approximately 16 hrs. The analysis of the ratio of AVP mRNA to 18S-rRNA suggested that AVP mRNA was degraded postmortem more rapidly than rRNA. These results suggest that autopsied human brains should be used for AVP mRNA study within a short postmortem time.

Animals↗
PubMed1977

Electron microscopic studies of purified eukaryote messenger RNA.

Rat liver mRNA, hen and rabbit globin messenger RNA (mRNA) were investigated by electron microscopy. No secondary structures were visible in the molecules of these mRNAs under conditions where short secondary structures of other types of RNA, i.e. MS2 phage RNA and 28 S rRNA, were clearly demonstrated. The contour lengths of these mRNAs were also determined by electron microscopy and compared with the sizes estimated by other techniques. The contour lengths of rabbit short and long globin mRNA are 0.1498 +/- 0.0019 and 0.1908 +/- 0.0021 micrometer, respectively. The former is assumed to be globin mRNA for alpha chain and the latter for beta chain. Similarly, hen "alpha" and "beta" globin mRNA have mean lengths of 0.1449 +/- 0.0011 and 0.1891 +/- 0.0017 micrometer, respectively. Hen and rabbit reticulocytes contain 1.8-2.0 times as much mRNA for alpha globin chains as for beta.

Animals↗
PubMed1986

Messenger RNA of the M segment RNA of Rift Valley fever virus.

The putative messenger RNA (mRNA) of the M segment RNA of the phlebovirus Rift Valley fever virus (RVFV) has been characterized using S1 nuclease mapping and oligonucleotide primer extension procedures. These experiments revealed that the 3' end of the mRNA lacks approximately 112 nucleotides of the M genomic RNA sequences, and that the 5' end of the mRNA possesses all of the sequences present at the 3' end of the M RNA but is further extended beyond the end of the genome by some 12-14 nucleotides of unknown origin. The implications of these data are discussed in relation to the replication and expression strategy of this virus.

Base Sequence↗
PubMed1975

Direct association of messenger RNA with microsomal membranes in human diploid fibroblasts.

Messenger RNA (mRNA) of membrane-bound polysomes in a membrane fraction of WI-38 cells remains associated with the microsomal membranes even after ribosomes and their nascent polypeptide chains are removed by using puromycin in a high salt buffer or by disassembling the ribosomes in a medium of high ionic strength lacking magnesium. mRNA either was specifically labeled in the presence of actinomycin D, or it was recognized by virtue of its affinity for oligo-dT. Poly A segments in bound mRNAs have an electrophoretic mobility in acrylamide gels which is characteristic of cytoplasmic mRNAs and corresponds to 150-200 adenyl residues. Extensive RNase treatment did not lead to release of the poly A segments of membrane-associated mRNA molecules either from an intact membrane fraction or from a membrane fraction previously stripped of ribosomes. On the other hand, RNase treatment led to the release and digestion of the nonpoly A segments of the mRNA molecules, indicating that the site of attachment of mRNA to the ER membranes is located near or at the 3' end of the molecule which contains the poly A. A direct association of mRNAs and endoplasmic reticulum membranes is considered in a modelto explain the assembly of bound polysomes and protein synthesis in a membrane-associated apparatus.

Adenosine Monophosphate↗
PubMed1975

Characteristics of messenger ribonucleoprotein and putative messenger RNA from Ehrlich ascites tumor cells.

Ehrlich ascites tumor cell messenger ribonucleoprotein (mRNP) and putative messenger RNA (mRNA) were isolated under conditions minimizing RNA degradation by ribonucleases and non-specific protein-RNA interaction, mRNP dissociated from polysomes by puromycin and EDTA sedimented to 185S. Putative messenger RNA released by proteinase K sedimented from 50 to 97S, with a maximum molecular weight approximating 6-25 X 10(6) daltons.

Animals↗
PubMed1992

Lesion of the nigrostriatal pathway induces cholecystokinin messenger RNA expression in the rat striatum. An in situ hybridization histochemistry study.

In situ hybridization histochemistry was used to investigate the putative regulation of cholecystokinin messenger RNA expression by dopamine in the rat striatum. Using this method, cholecystokinin messenger RNA was undetectable in the normal rat striatum. Dopamine depletion caused by a 6-hydroxydopamine injection in the medical forebrain bundle induced, two and four weeks after the injection, an increase of cholecystokinin messenger RNA expression in the ipsilateral striatum. The labeling was mostly restricted to the dorsolateral quadrant. At the cellular level, this corresponded to a slight but significant labeling of a moderate density of striatal neurons which most probably represent a subpopulation of medium-sized spiny neurons. Conversely, treatment with either haloperidol or SCH23390 for two weeks did not induce any detectable changes in cholecystokinin messenger RNA expression in the striatum while, as expected, an increase in the striatal enkephalin messenger RNA content was observed. These results suggest that the dopaminergic nigrostriatal pathway directly, or indirectly, regulates the expression of cholecystokinin messenger RNA in the striatum.

Animals↗
PubMed2003

Amyloid peptide-induced cytokine and chemokine expression in THP-1 monocytes is blocked by small inhibitory RNA duplexes for early growth response-1 messenger RNA.

In Alzheimer's disease (AD) one finds increased deposition of A beta and also an increased presence of monocytes/macrophages in the vessel wall and activated microglial cells in the brain. AD patients show increased levels of proinflammatory cytokines by activated microglia. Here we used a human monocytic THP-1 cell line as a model for microglia to delineate the cellular signaling mechanism involved in amyloid peptides (A beta(1-40) and A beta(1-42))-induced expression of inflammatory cytokines and chemokines. We observed that A beta peptides at physiological concentrations (125 nM) increased mRNA expression of cytokines (TNF-alpha, and IL-1 beta) and chemokines (monocyte chemoattractant protein-1 (MCP-1), IL-8, and macrophage inflammatory protein-1 beta (MIP-1 beta)). The cellular signaling involved activation of c-Raf, extracellular signal-regulated kinase-1 (ERK-1)/ERK-2, and c-Jun N-terminal kinase, but not p38 mitogen-activated protein kinase. This is further supported by the data showing that A beta causes phosphorylation of ERK-1/ERK-2, which, in turn, activates Elk-1. Furthermore, A beta mediated a time-dependent increase in DNA binding activity of early growth response-1 (Egr-1) and AP-1, but not of NF-kappa B and CREB. Moreover, A beta-induced Egr-1 DNA binding activity was reduced >60% in THP-1 cells transfected with small interfering RNA duplexes for Egr-1 mRNA. We show that A beta-induced expression of TNF-alpha, IL-1 beta, MCP-1, IL-8, and MIP-1 beta was abrogated in Egr-1 small inhibitory RNA-transfected cells. Our results indicate that A beta-induced expression of cytokines (TNF-alpha and IL-1 beta) and chemokines (MCP-1, IL-8, and MIP-1 beta) in THP-1 monocytes involves activation of ERK-1/ERK-2 and downstream activation of Egr-1. The inhibition of Egr-1 by Egr-1 small inhibitory RNA may represent a potential therapeutic target to ameliorate the inflammation and progression of AD.

Amyloid beta-Peptides↗
PubMed1973

Enzymatic synthesis of DNA complementary to purified 14S messenger RNA of immunoglobulin light chain.

The 14S messenger RNA, which contains poly(adenylic acid), of MOPC 41 (mouse plasmocytoma) immunoglobulin light chain, purified to a single peak as shown by polyacrylamide gel electrophoresis, was used to synthesize complementary DNA with the RNA-dependent DNA polymerase of avian myeloblastosis virus. DNA synthesis is entirely dependent on added RNA template and oligo(dT) primer. Both the size and the concentration of the primer affect the reaction. The product behaves similarly to DNA during centrifugation in cesium sulfate density gradients. It is shown by hybridization that the DNA made is complementary to the purified template, light-chain mRNA. The high specific activity of the complementary DNA should make it suitable for gene-dosage experiments. According to alkaline sucrose gradient analyses, some complete complementary DNA transcripts of the 14S mRNA seem to be made. Oligo(dG) can also function as a primer for DNA synthesis, possibly by annealing to an internal cluster of cytidines in the mRNA, that correspond to the bases coding for amino-acids 119 and 120 of the MOPC 41 light chain.

Animals↗
PubMed2000

[Correlation between epidermal growth factor receptor messenger RNA expression and the onset of labor].

OBJECTIVE: To study the correlation between epidermal growth factor receptor messenger RNA expression and the onset of labor. METHOD: Semiquantitative reverse transcriptase polymerase chain reaction, using GAPDH as internal standard, was applied to determine the levels of epidermal growth factor receptor messenger RNA in human myometrium (n = 20) and fetal membranes (n = 20) before and during labor. RESULTS: In myometrium, epidermal growth factor receptor messenger RNA increased from 0.91 +/- 0.32 before labor to 1.33 +/- 0.23 after the onset of labor (P < 0.05). In fetal membranes, epidermal growth factor receptor messenger RNA increased from 1.05 +/- 0.30 before labor to 1.65 +/- 0.71 after the onset of labor (P < 0.05). CONCLUSION: The study indicates it is Up-regulation of epidermal growth factor receptors messenger RNA expression in myometrium and fetal membrane before and after the onset of labor.

Amnion↗