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At least 289 records · Page 16Linked to original sources
PubMed2000

Relevance between striatal expression of Fos, proenkephalin mRNA, prodynorphin mRNA and rotation induced by l-stepholidine in 6-hydroxydopamine-lesioned rats.

AIM: To study that l-stepholidine (SPD) regulates the expression of proenkephalin (PENK) and prodynorphin (PDYN) mRNA and Fos in the striatum after rotational test in the 6-hydroxydopamine (6-OHDA)-lesioned rats. METHODS: PENK and PDYN mRNA levels were examined with in situ hybridization, and Fos expression was detected with immunocytochemistry. The data were semi-quantified with image analyzer. RESULTS: (1) Following repeated SPD treatment, the rotation was kept on high activity in the 6-OHDA-lesioned rats. (2) SPD significantly elicited Fos expression in both sides of striatum, particularly in the denervated one. Repeated administration of SPD, Fos expression declined on both sides, particularly in the intact one. (3) In the denervated striatum of 6-OHDA-lesioned rats, the PENK mRNA level was extremely increased vs that in the intact striatum. This high level of PENK mRNA was significantly reduced by 7-d treatments of SPD. SPD also reduced the level of PENK mRNA in the intact striatum. However, the level of PDYN mRNA did not show significant change in both sides of striatum after denervation or SPD treatment. CONCLUSION: In the 6-OHDA-lesioned rats, the rotation induced by SPD was kept on a high activity, which was in pace with the inducement of Fos expression and the reduction of expression of PENK mRNA in the denervated striatum. But then the lesion and SPD treatment had no remarkable effect on the expression of PDYN mRNA.

Animals↗
PubMed1992

Quantitative analysis of transcription and RNA levels of 15 barley chloroplast genes. Transcription rates and mRNA levels vary over 300-fold; predicted mRNA stabilities vary 30-fold.

Higher plant plastid genomes encode rRNAs, tRNAs, and protein subunits of the RNA polymerase, ribosomes, and the photosynthetic apparatus which vary over 1000-fold in abundance. Quantitative analysis of transcription and RNA levels was carried out on 15 plastid genes which are located in 14 different transcription units covering 50% of the barley plastid genome. Transcription of 16S rRNA, trnfM-trnG, and trnK was high relative to most other plastid genes. Transcription of trnfM-trnG was 5 times greater than trnK indicating that differences in tRNA levels in plastids could be due, in part, to differences in transcription. Among the protein coding genes, mRNA levels varied over 900-fold and transcription over 300-fold. The gene showing the lowest transcription rate and mRNA level, rpoB, is located in a gene cluster which encodes subunits of the plastid RNA polymerase (rpoB-rpoC1-rpoC2). RpoA, which encodes the alpha subunit of the RNA polymerase, was located in a gene cluster encoding ribosomal proteins (rpl23, rps19, rpl16) and infA. RNA from this gene cluster is 30-fold more abundant than rpoB mRNA, suggesting that expression of rpoA is regulated at the level of translation or protein stability. Polycistronic operons encoding subunits of the photosynthetic apparatus (psbB-psbH-petB-petD; psbK-psbI-psbD-psbC; atpB-atpE; psaA-psaB) had higher transcription rates and correspondingly higher mRNA levels than genes which encode ribosomal proteins or RNA polymerase subunits. RbcL and psbA, which are located in separate transcription units, exhibited the highest transcription rates and mRNA levels. Correspondence between transcription rate, mRNA level, and protein abundance indicates that transcription is a primary determinant of barley plastid gene expression. In addition, a 30-fold variation in predicted mRNA stability was observed which further increases the dynamic range of plastid mRNA abundance.

Base Sequence↗
PubMed2003

[Eosinophils apoptosis, fas mRNA and bcl-2 mRNA expressions in asthma model of young rat and effects of achyranthes bidentata polysaccharides].

OBJECTIVE: Asthma is a chronic respiratory tract disorder characterized by airway hyperreaction (AHR), persistent airway inflammation, high serum IgE, overproduction of IL-4, IL-5 and IL-13 by allergen-specific Th2 cells. The morbidity and mortality of asthma have continued to increase despite the use of currently available therapeutic agents. The reputed effects of traditional Chinese medicines (TCMs) have led to increasing use of TCMs for treatment of asthma throughout the world. The aims of this study were to investigate in asthma model of young rat the mRNA expressions of apoptotic gene fas and bcl-2, eosinophils (EOS) apoptosis in airway, and effects of achyranthes bidentata polysaccharides (ABPS), a group of polysaccharides extracted from TCM Achyranthes bidentata blume, on treatment of asthma. METHODS: Fifty Sprague-Dawley (SD) rats were divided into five groups, 10 rats per group. Asthma in rats was induced by intraperitioneal sensitization and challenge with nebulized ovalbumin (OVA). A pretreatment with ABPS [50 mg/(kg x d)] was done according to three different schedules: consecutively 3 days at sensitization (T1), at challenge (T2) or both of the two periods (T3). Sham-treated rats (A) and naive rats (C) served as controls. The animals were sacrificed 24 hours after the last challenge. The mRNA expression of bcl-2 and fas in eosinophils presenting in airway and the apoptosis of eosinophils in airway were assessed by using in situ hybridization with oligonucleotide probe and TUNEL methods, respectively. RESULTS: (1) Twenty-four hours after the last antigen challenge, the mRNA expression of fas in eosinophils presenting in airway significantly decreased in group A [(43.4 +/- 10.0)%] compared with that in group C [(73.2 +/- 11.9)%] (P < 0.01). ABPS could increase the fas mRNA expression significantly in all the three groups [(59.0 +/- 8.1)%, (57.5 +/- 9.6)%, (76.2 +/- 2.7)%], compared with that in group A (P < 0.05, P < 0.05, P < 0.01, respectively). The expression of the bcl-2 mRNA in group C was (47.9 +/- 8.7)%, it was elevated to (67.4 +/- 7.3)% in group A (P < 0.01). The expression of the bcl-2 mRNA in ABPS treated T1 and T3 groups was significantly lowered [(57.7 +/- 12.7)%, (57.3 +/- 6.8)%, P < 0.05], but not in T2 group [(72.4 +/- 6.7)%]. (2) In group A, the EOS presenting in the airway increased significantly, but there were few apoptotic EOS; the percentage of apoptotic eosinophil was distinctly lower in group A than that in group C [(5.3 +/- 2.2)% vs. (15.9 +/- 2.4)%, P < 0.01]. Compared with that in group A, the eosinophil apoptosis ratio in those ABPS treated groups T1, T3 was evidently elevated [(8.7 +/- 2.9)%, (9.8 +/- 2.2)%, P < 0.05, P < 0.05], but ABPS treated at challenge (T2) could not change the eosinophil apoptosis ratio significantly (P > 0.05). CONCLUSION: (1) In asthmatic rat, the expressions of the genes fas and bcl-2 mRNA in EOS were changed evidently and the ratio of EOS apoptotosis reduced greatly. (2) ABPS could enhance the apoptosis of EOS by upregulating the expression of the genes fas and bcl-2 mRNA.

Achyranthes↗
PubMed2004

[Expression and significance of EGF mRNA and EGFR mRNA in hepatocellular carcinoma].

BACKGROUND & OBJECTIVE: Many evidences demonstrated that the epidermal growth factor receptor (EGFR) subfamily played an important role in they initiation and progression of various cancers. But it is not clear whether there is a relationship between EGFR and hepatocellular carcinoma (HCC). The aims of the present study were to explore the expression and significance of the epidermal growth factor (EGF) mRNA and EGFR mRNA in human HCC tissues. METHODS: Reverse transcription polymerase chain reaction (RT-PCR) was employed to determine the expression of EGF mRNA and EGFR mRNA in 60 HCC tissues and their adjacent liver tissues. RESULTS: The positive rate of EGF mRNA was significantly lower in the HCC tissue (60%, 36/60) than in the adjacent liver tissue (80%, 48/60) (P< 0.05). The positive rate of EGFR mRNA in the HCC tissue (60%, 36/60) was markedly higher than in the adjacent liver tissue (41.67%, 25/60) (P< 0.05). The expression of EGFR mRNA in the HCC tissue was significantly correlated with the clinical stage, the portal vein tumor thrombus, the presence of extrahepatic metastasis, and the recurrence of tumor, the number of tumor, but not correlated with the diameter of tumor, the level of serum alpha-fetoprotein (AFP), the differentiation of tumor and the liver cirrhosis in the adjacent tissue. The detectable rate of EGF mRNA was correlated with the diameter of tumor but not correlated with the clinical stage, the portal vein tumor thrombus, the presence of extrahepatic metastasis, the recurrence of tumor, the number of tumor, the level of serum AFP, the differentiation of tumor and the liver cirrhosis in the adjacent tissue. CONCLUSIONS: EGF may not be involved in the initiation and progression of HCC, whereas, EGFR relates to the initiation and progression and the recurrence of HCC. EGFR can be considered as a marker for predicting the metastasis and recurrence of HCC.

Adult↗
PubMed2004

[Combined detection of CEA mRNA and CK 19 mRNA in peripheral blood cells of patients with lung cancer].

OBJECTIVE: To investigate the expression of CEA mRNA and CK(19) mRNA in peripheral blood cells of patients with lung cancer and evaluate its clinical significance. METHODS: Peripheral blood nucleated cells of 50 patients with lung cancer were studied by RT-PCR to detect the expression of CEA mRNA and CK(19) mRNA. RESULTS: The combined positive rate of CEA mRNA and CK(19) mRNA in patients with lung cancer (82.0%) was significantly higher than that in patients with benign lung diseases (28.0%) and healthy volunteers (8.1%) (P < 0.001). The expression rate had no relation to the clinical staging or histological type. Compared with single detection, combined detection increased the detection rate but did not decrease the specificity. CONCLUSION: Combined detection of CEA mRNA and CK(19) mRNA expression in peripheral blood nucleated cells increase the sensitivity of detecting hematogenous dissemination of cancer cells. Long-term survival analysis and more specimens would be helpful for evaluating its clinical significance.

Adenocarcinoma↗
PubMed2005

[Influence of macrophages on the expression of vascular endothelial growth factor receptor mRNA, homeobox B2 mRNA, and integrin alpha nu beta3 in vascular endothelial strain].

OBJECTIVE: To investigate the influence of macrophages on the expression of the vascular endothelial growth factor (VEGF) receptor (KDR) mRNA, homeobox B2 (HOXB2) mRNA, and integrin alpha nu beta3 in vitro in vascular endothelial strain. METHODS: Human umbilical vein cells (ECV304) were cultured in vitro and divided into 4 groups, i.e. (1) ECV304 group, (2) ECV304 + conA group [with conA (25 microg/ml in culture) added to ECV304], (3) ECV304 + U937 group (with 1 x 10(5)/ml of U937 cells added to 1 x 10(5)/ml ECV 304), (4) ECV304 + U937 + conA group [with 1 x 10(5)/ml of U937 cells and conA (25 microg/ml in culture)] groups. Forty-eight hours after culturing, the expression of integrin receptor alpha nu beta3 and the changes in the expression of KDR mRNA and HOXB2 mRNA in each group were determined by immunofluorescent technique and RT-PCR, respectively. RESULTS: The expression of integrin receptor alpha nu beta3, KDR mRNA, and HOXB2 mRNA in ECV304 group were 6.7 +/- 1.5, 0.633 +/- 0.012, and 0.674 +/- 0.004, respectively, while those in ECV304 + U937 + conA group (10.2 +/- 1.7, 0.879 +/- 0.003, 0.947 +/- 0.003) were obviously more upregulated when compared with those in ECV304 group (P < 0.01). No difference in the above indices was found between ECV304 and ECV304 + conA, ECV304 + U937 groups (P > 0.05). CONCLUSION: Macrophages activated by ConA can accelerate the proliferation, migration and adhesion to the basement membrane matrix of vascular endothelial cells through the influence on the expression of KDR mRNA, HOXB2 mRNA and integrin alpha nu beta3, and through this pathway the angiogenesis is modulated.

Cells, Cultured↗
PubMed2006

Changes of learning, memory and levels of CaMKII, CaM mRNA, CREB mRNA in the hippocampus of chronic multiple-stressed rats.

BACKGROUND: The effect of chronic stress on cognitive functions has been one of the hot topic in neuroscience. But there has been much controversy over its mechanism. Such single stressor applied in the past could not simulate complicated living circumstances that people confronted with. The aim of this study was to investigate the effects of chronic multiple-stress on learning and memory as well as on the levels of calcium/calmodulin-dependent protein kinase II (CaMKII), calmodulin (CaM) mRNA, and cAMP-response element binding protein (CREB) mRNA in the hippocampus of rats. METHODS: The rats were divided randomly into stressed and control groups. The stressed group was given chronic multiple-stress for 6 weeks to set up a chronic multiple-stressed model. The rats' performance of spatial learning and memory was tested using Morris Water Maze (MWM) and Y-maze. Meanwhile, the expressions of CaMKII, CaM mRNA and CREB mRNA of rats' hippocampus were detected by immunohistochemistry, Western blot and reverse transcription-polymerase chain reaction (RT-PCR), respectively. In addition, the width of synaptic cleft and the thickness of post-synaptic densities (PSD) were observed in the hippocampal CA3 region of rats by electron microscopy. RESULTS: After exposure to chronic multiple-stress for 6 weeks, the ability of learning and memory of the stressed group was higher than that of the control group (P < 0.05, P < 0.01). The width of synaptic cleft was smaller and the thickness of PSD was larger in the hippocampal CA3 region of the stressed group than in that of the control group (P < 0.01). The CaMK II immunostaining of the stressed group was stronger than that of the control group in the stratum radiatum and oriens of the hippocampal CA1 and CA3, especially in the stratum oriens. Quantitative analysis indicated that the expression of CaMK II, CaM mRNA, and CREB mRNA in the hippocampus of the stressed group was higher than that of the control group (P < 0.05, P < 0.01). CONCLUSIONS: The capacity of learning and memory can be enhanced after chronic multiple-stress. The increased levels of CaMK II, CaM mRNA, and CREB mRNA may contribute to the enhancing effect of chronic multiple-stress on learning and memory.

Animals↗
PubMed1985

Secondary structure analysis of apolipoprotein II mRNA using enzymatic probes and reverse transcriptase. Evaluation of primer extension for high resolution structure mapping of mRNA.

Primer extension has been employed to locate sites of cleavage made in apolipoprotein II (apo-II) mRNA by structure-specific nucleases. This approach permits structural analysis of specific mRNAs within a complex population. Electrophoretic analysis of cDNAs synthesized from T1 RNase-treated and mock-treated apo-II mRNA revealed that most cleavage sites can be mapped with single nucleotide accuracy. However, some T1 RNase-dependent cDNAs demonstrated mobilities corresponding to one nucleotide longer than the mRNA template, suggesting that reverse transcriptase can add a single nucleotide to full-length cDNAs in a template-independent reaction. This approach has been used to map double-stranded and single-stranded accessible domains of the 3' noncoding region of apo-II mRNA with cobra venom, T1, and S1 ribonucleases. Cleavage profiles of apo-II mRNA renatured under a variety of buffer and temperature conditions were identical and in no case was overlap observed between sites of cleavage by double strand- and single strand-specific enzymes. These results suggest that apo-II mRNA possesses a predominant, stable secondary structure. A computer-generated structure model, consistent with these nuclease cleavage data, is presented. In addition to the analysis of mRNA higher order structure in mixed RNA populations, this approach also appears suitable for the analysis of protein-mRNA interactions. Termination sites of incomplete cDNAs produced when untreated or mock-treated RNA is used as a template for primer extension were also mapped. This analysis revealed an over-representation of termination at the dinucleotides CA and CU, suggesting that termination of some incomplete apo-II cDNAs is related to primary and not secondary structure. Such sequence dependence could reflect in vivo degradation by an endogenous cytidine-specific nuclease.

Animals↗
PubMed1989

B cell response pathways regulated by IL-5 and IL-2. Secretory microH chain-mRNA and J chain mRNA expression are separately controlled events.

We have examined the effect of IL-5 and/or IL-2 on the expression of the secretory form of microH chain (microsecond) and J chain mRNA in a homogeneous neoplastic B cell clone, in which proliferation, IL-2R up-regulation and entry into the IgM secretory state are separately controlled events. The IL-5 signal triggers a partial induction of CL-3 cells into the IgM secretory state, characterized by a striking increase of microsecond mRNA expression and an increase in the ratio of the secretory to membrane forms of microH chain mRNA, with a modest increase of J chain mRNA. In contrast, amplification of J chain mRNA is accomplished by the late-acting B cell differentiation stimulus, IL-2, acting on IL-5-pretreated CL-3 cells or acting simultaneously with IL-5 on CL-3 cells. Such dually stimulated cells now are fully induced into IgM secreting cells. These results define the relative roles of IL-5 and IL-2 in B cell differentiation by showing important regulatory effects at the mRNA level. In addition, these results substantiate that appearance of mRNA for J chain, a molecule key to the formation of pentameric IgM, is a limiting factor for high level IgM secretion. The separate control of microsecond and J chain mRNA found in CL-3 cells stimulated with IL-5 and IL-2 elucidates a molecular mechanism by which these two lymphokines synergize in the development of CL-3 cells into IgM secreting cells.

B-Lymphocytes↗
PubMed1987

Structure and expression of murine malic enzyme mRNA. Differentiation-dependent accumulation of two forms of malic enzyme mRNA in 3T3-L1 cells.

Many murine cells express two mRNAs with markedly different sizes (2.0 and 3.1 kilobases (kb)) that hybridize with cDNA probes for cytosolic malic enzyme ((S)-malate NADP+ oxidoreductase (oxaloacetate-decarboxylating, EC 1.1.1.40). A series of overlapping cDNA clones corresponding to 3129 nucleotides of malic enzyme mRNA was isolated and sequenced to determine the relationship between the two mRNAs and establish the primary structure of mouse malic enzyme. The larger mRNA has an open reading frame of 1716 nucleotides followed by a 3' untranslated region of 1348 nucleotides. The sequence of an exceptionally G/C-rich (88%) portion (65 nucleotides) of the 5' noncoding region was also established. An uncommon poly A addition signal (AUUAAA) is used during the processing of the 3.1-kb mRNA. The 2.0-kb mRNA results from the utilization of another poly A addition signal that truncates the 3' noncoding sequence by approximately 1 kb. The mRNA coding sequence indicates that the malic enzyme subunit contains 572 amino acid residues and has a Mr of 64,000. Two putative components of an NADP-binding domain are located between residues 100 and 165. During the differentiation of 3T3-L1 preadipocytes into adipocytes both the rate of synthesis and relative mRNA concentration for malic enzyme and another lipogenic enzyme, ATP-citrate lyase, are coordinately increased 5-7-fold. However, as preadipocytes approach confluence, the mRNA levels for both lipogenic enzymes transiently increase 3-4-fold, whereas the rates of synthesis of the two proteins are only slightly elevated. Thus, lipogenic enzyme expression is controlled at a pretranslational level during adipogenesis, but the accumulation of the same enzymes may also be subject to translational control in the fibroblast-like preadipocytes. In contrast, mRNA coding for a third enzyme required for lipogenesis, glycerol-3-phosphate dehydrogenase, is not detected in 3T3-L1 preadipocytes, but rapidly accumulates during adipocyte development.

Adipose Tissue↗
PubMedDate not supplied

[Structure of nuclear pre-mRNA. XI. Triphosphorylated and blocked 5'-ends in the pre-mRNA].

The nature of the 5'-termini in pre-mRNA isolated from Ehrlich carcinoma cells has been investigated. To discriminate between triphosphorylated 5'-ends and capped structures different methods were used including treatment by alkaline phosphatase and several chromatographic methods. It was shown that heavey pre-mRNA contains a significant number of non-blocked triphosphorylated nucleotides at the 5'-end termini. However, phosphatase resistent, blocked 5'-termini were also found. 5'-terminal nucleotides in triphosphorylated pre-mRNA are G in a 3 : 2 ratio. In contrast to nuclear pre-mRNA cytoplasmic poly(A)+mRNA does not contain triphosphorylated 5'-ends but does contain the "cap" structure only. To elucidate the pre-mRNA topography the localization of homopolymeric regions of pre-mRNA, poly(A) and oligo(U), in relation to 5'terminal structures has been investigated. The experiments showed that the distance between 3'-terminal poly(A) sequences and 5'-end triphosphates is longer than 1500--2000 nucleotides. At the same time the distance between the latter and oligo(U) in pre-mRNA is much shorter.

Alkaline Phosphatase↗
PubMed1983

Molecular cloning of DNA complementary to rat L-type pyruvate kinase mRNA. Nutritional and hormonal regulation of L-type pyruvate kinase mRNA concentration.

Rat liver L-type pyruvate kinase mRNA was enriched from total polysomes by immunoprecipitation with a specific antibody and Staphylococcus aureus cells. Double-stranded cDNA synthesized from the enriched mRNA was inserted into the PstI site of pBR322, and the resultant recombinant DNA molecules were used to transform Escherichia coli. Three clones containing DNA complementary to L-type pyruvate kinase mRNA were identified by colony hybridization, hybrid-selected translation, and dot blot hybridization. A partial restriction endonuclease map of cDNA inserts was constructed covering about 1.86 kilobase pairs. The cDNA insert of recombinant plasmid pLPK-14 was used as a hybridization probe to quantitate L-type pyruvate kinase mRNA in rat liver after various treatments. The level of hybridizable L-type enzyme mRNA was markedly increased by a high carbohydrate diet. Diabetes greatly reduced the mRNA level in the liver of rats maintained on a high carbohydrate diet, but insulin administration resulted in restoration of the mRNA level to normal within 24 h. These changes were approximately proportional to the changes in the level of translatable L-type pyruvate kinase mRNA. Thus, we conclude that nutritional and hormonal regulation of synthesis of hepatic L-type pyruvate kinase occurs at the pretranslational level.

Animals↗
PubMed1983

Regulation of ferritin mRNA: a possible gene-sparing phenomenon. Induction of ferritin synthesis by iron in liver as well as red cells combines high translational efficiency with increased utilization of preformed ferritin mRNA.

Control of ferritin synthesis by iron at the level of transcription is potentially hazardous to DNA because of the iron-catalyzed degradation of DNA. The induction of ferritin synthesis in reticulocytes of embryos (bullfrog tadpoles) occurs by two types of translational control i.e. increased availability of stored ferritin mRNA, in response to iron, coupled with a high translational efficiency. Since erythroid cell nuclei have large amounts of heterochromatin and may be relatively inactive genetically, the translational control of ferritin by iron observed in red cells was studied in other tissue by isolating poly (A+) RNA from tadpole liver and analyzing protein synthesis in vitro. Liver ferritin mRNA directed the synthesis of 7.0% of the protein in a wheat germ system, compared to 1.2% in vivo, suggesting that tadpole liver contained a large amount of stored ferritin mRNA. At levels of poly (A+) RNA which were saturating for total protein synthesis, ferritin synthesis was still linearly dependent upon RNA concentration, indicating a high efficiency of translation of ferritin mRNA. The results are analogous to those previously observed in red cells and confirm the storage of ferritin mRNA deduced from studies of the polysomal and nonpolysomal distribution of the mRNA in rat liver. The results indicate that the increased availability for translation of stored ferritin mRNA, in response to iron, and the high translational efficiency of ferritin mRNA are a general characteristic of ferritin synthesis rather than a specific feature of red cell maturation. This novel form of regulation of ferritin gene expression can be attributed to a need to protect DNA from degradation by iron and oxygen. The normal barrier between DNA and iron is apparently breached by the iron-oxygen complex of the drug bleomycin, an antitumor agent thought to act in vivo by iron-catalyzed cleavage of DNA.

Animals↗
PubMed1981

Physical and biological properties of an epsilon-heavy chain mRNA and a kappa-light chain mRNA coding for rat immunoglobulin E.

The mRNA coding for epsilon-heavy chain and kappa-light chain have been highly enriched from a rat IgE-producing myeloma, IR-162. Based on denaturing gel analyses, the 20 S epsilon-heavy chain mRNA has an estimated molecular weight of 850,000, equivalent to about 2500 nucleotides. The 14S rat kappa-light chain mRNA has an estimated molecular weight of 410,000, equivalent to about 1200 nucleotides. Only about two-thirds of the length of these mature cytoplasmic rat mRNA code for protein. The 20 S mRNA stimulates the in vitro synthesis of a single major serologically related protein which is large enough to be epsilon-heavy chain. It is unglycosylated and has an apparent molecular weight of about 62,000. The in vivo unglycosylated epsilon-heavy chain, obtained in the presence of tunicamycin, has an apparent molecular weight of about 59,000, compared with about 76,000 for the glycosylated heavy chain of the secreted rat IgE. Therefore, the in vitro synthesized epsilon-heavy chain protein is about Mr = 3000 larger than the in vivo unglycosylated epsilon-heavy chain, equivalent to about 25 extra amino acids. This is consistent with the synthesis of an epsilon-heavy chain putative precursor. Likewise, the 14 S mRNA stimulates the in vitro synthesis of a single putative precursor protein, which is serologically related to kappa chain, is unglycosylated, and is about an extra 20 amino acids. This is the first report on the physical and biological properties of an epsilon-heavy chain mRNA, as well as any rat immunoglobulin mRNA.

Animals↗
PubMed2006

Two mRNA-binding proteins regulate the distribution of syntaxin mRNA in Aplysia sensory neurons.

Targeting mRNAs to different functional domains within neurons is crucial to memory storage. In Aplysia sensory neurons, syntaxin mRNA accumulates at the axon hillock during long-term facilitation of sensory-motor neuron synapses produced by serotonin (5-HT). We find that the 3' untranslated region of Aplysia syntaxin mRNA has two targeting elements, the cytosolic polyadenylation element (CPE) and stem-loop double-stranded structures that appear to interact with mRNA-binding proteins CPEB and Staufen. Blocking the interaction between these targeting elements and their RNA-binding proteins abolished both accumulation at the axon hillock and long-term facilitation. CPEB, which we previously have shown to be upregulated after stimulation with 5-HT, is required for the relocalization of syntaxin mRNA to the axon hillock from the opposite pole in the cell body of the sensory neuron during long-term facilitation, whereas Staufen is required for maintaining the accumulation of the mRNA both at the axon hillock after the treatment with 5-HT and at the opposite pole in stable, unstimulated sensory neurons. Thus, the cooperative actions of the two mRNA-binding proteins serve to direct the distribution of an mRNA encoding a key synaptic protein.

Animals↗
PubMed1996

Conditional inactivation of mRNA capping enzyme affects yeast pre-mRNA splicing in vivo.

Acquisition of the 5'cap is the earliest modification event during eukaryotic mRNA synthesis. The cap is thought to facilitate later processing steps, such as pre-mRNA splicing. If this is so, then a defect in cap synthesis should impact on splicing in vivo. We tested this hypothesis by examining the consequences of conditional inactivation of the Saccharomyces cerevisiae CEG1 gene, which encodes mRNA guanylyltransferase (capping enzyme). Two different ceg1-ts mutants, Y66A and C354Y, displayed a pre-mRNA processing (prp) defect, characterized by an increase in the amount of unspliced pre-mRNA after shift to nonpermissive temperature and a decrease in the amount of mature mRNA. The guanylyltransferase activities of the Y66A and C354Y proteins were thermolabile, suggesting that defective capping in vivo was contributory to the prp phenotype. Although these results provide the first genetic link between capping and splicing in vivo, we were unable to demonstrate a role for either the cap or the capping enzyme during yeast pre-mRNA splicing in vitro.

Alleles↗
PubMed1981

Regulation of gene expression by tumor promoters. III. Complementation of the developmental program in myeloid leukemic cells by regulating mRNA production and mRNA translation.

Regulation of gene expression has been analysed in different clones of mouse myeloid leukemic cells treated with the tumor promoter 12-0-tetradecanoyl-phorbol-13-acetate (TPA), the macrophage- and granulocyte-inducing protein MGI, and combined treatment with TPA and MGI. Two-dimensional gel electrophoresis was used to measure changes in the rate of synthesis of specific proteins and in the amount of corresponding translatable mRNAs assayed in the reticulocyte cell-free translation system. TPA induced different subsets of differentiation-associated protein changes in the different clones and the degree of response to TPA was not necessarily related to the degree of response to MGI. It is shown that TPA can induce protein changes either by inducing the synthesis of new mRNA, by increasing or decreasing the amount of pre-existing mRNA, or by modulating the translation of a constant amount of mRNA. Combined treatment with TPA and MGI resulted in an enhancement of protein changes induced by MGI or TPA alone and induced differentiation-associated protein changes not induced by either compound separately in differentiation-defective clones. This complementation of gene expression appeared to be due to each compound inducing functions not induced by the other, so that the combined treatment resulted in new gene expression. Complementation also occurred at the level both of mRNA production and of mRNA translation. It is suggested that the ability of TPA to regulate gene expression at the level of mRNA production and mRNA translation and to complement changes in gene expression induced by other compounds such as MGI are important functions for its role as a tumor promoter.

Animals↗
PubMed1994

Mechanism of post-segregational killing: Sok antisense RNA interacts with Hok mRNA via its 5'-end single-stranded leader and competes with the 3'-end of Hok mRNA for binding to the mok translational initiation region.

The hok/sok system of plasmid R1, which mediates plasmid stabilization by killing of plasmid-free segregants, codes for two RNA species, Hok mRNA and Sok antisense RNA. The lethal expression of hok is inhibited post-transcriptionally by the 67 nt Sok-RNA. In this paper, we analyse the secondary structure of Sok-RNA and the binding of Sok-RNA to Hok mRNA in vitro. The reaction between the two RNAs leads to the formation of a complete duplex in which Sok-RNA is hybridized over its entire length to Hok mRNA. The second-order rate constant of duplex formation was determined to be approximately 1 x 10(5) M-1s-1. Mutations in the 5'-end single-stranded leader of Sok-RNA severely reduced the binding rate to wt Hok mRNA, whereas loop mutations in Sok-RNA had no such effect. The reduced binding rates were paralleled by abolished in vivo regulatory properties. These results suggest that, unlike in other well-characterized antisense/target RNA systems, the initial recognition reaction between Sok-RNA and Hok mRNA takes place between the single-stranded 5'-end of Sok-RNA and the complementary region in Hok mRNA, without the involvement of an antisense loop in the initial binding step. Furthermore, the finding that Sok-RNA competes with the 3'-end of full-length Hok mRNA for binding to the mok translational initiation region adds to the complexity of killer gene regulation.

Bacterial Proteins↗