Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.27.5 (RNase)
17,967 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The growth-related protein p23 of the Ehrlich ascites tumor (EAT) is preferentially expressed in the exponentially growing tumor; its synthesis is translationally controlled. p23 mRNA is efficiently translated in the wheat germ cell-free lysate. In contrast, p23 mRNA present in poly(A)+RNA isolated from EAT is not translated in cell-free systems of EAT and reticulocytes. Moreover, translation of a p23 transcript is inhibited in the presence of total poly(A)+RNA. This inhibition is abolished by the removal of the 5'-UTR of the p23 transcript. Solution hybridization/RNase protection experiments point to the presence of a nucleotide sequence complementary to the 5'-UTR of p23 mRNA which might be involved in p23 mRNA inhibition.
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PMID:The 5'-untranslated region of p23 mRNA from the Ehrlich ascites tumor is involved in translation control of the growth related protein p23. 172 16

Rat IGF-I mRNAs contain two different 5'-UTR sequences as a result of alternate splicing of leader exons. Using a combination of solution hybridization/RNase protection and primer extension assays, we have mapped the transcriptional start sites in these leader exons. There appear to be three putative transcription start sites in exon 1 spread over a 140-bp region, the most upstream of which defines a 381 bp-long exon 1. There appear to be three distinct start sites in exon 2, the most upstream of which defines a greater than 770 bp-long exon 2. The two downstream start sites in exon 1 together account for approximately 70% of IGF-I gene expression in adult rat liver. Essentially all of the remaining IGF-I gene expression comes from the second start site in exon 2. Rat IGF-I gene transcription may therefore be regulated by two distinct promoter regions, a disperse promoter for exon 1, with several transcription initiation sites, and a more typical promoter region for exon 2, which controls transcription initiation from a discrete region.
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PMID:Transcription initiation in the two leader exons of the rat IGF-I gene occurs from disperse versus localized sites. 202 99

In this paper we report the presence and function of the 5' untranslated region (5'UTR) from the mRNA encoding human gamma-glutamyltransferase (GGT) in three different hematopoietic cell lines (HL-60, U-937 and K-562) as well as in the RNA of the leukocyte fraction from six acute lymphoblastic leukemias (ALL). Results obtained by RNase protection analysis demonstrate the presence of a unique form of 5'UTR expressed in most human tissues. In order to investigate the possible role of this type of sequence on regulation of GGT in hematopoietic cells, plasmid constructs carrying human hepatoma GGT 5'UTR and a luciferase reporter gene were transfected into the three blood cell lines. Compared to control untransfected cells, transfected HL-60 and K-562 showed a decrease in reporter gene activity of 51 and 73%, respectively. In contrast, transfected U-937 showed a 139% increase of reporter gene activity. Results were compared to GGT activity in the relevant cells and we concluded that the 5'UTR appears to have a regulatory role in GGT expression as a tissue-specific modulator of translation.
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PMID:Characterization and regulatory effect of gamma-glutamyltransferase messenger RNA untranslated regions in human leukemia. 764 21

To examine the function of conserved noncoding regions in the erythropoietin (Epo) gene, we have prepared clones and pools of Hep3B cells stably transfected with a marked 4.1-kilobase Epo gene and deletions thereof. The marked transcripts had single base substitutions at three sites in the coding portion of Exon 5, enabling them to be distinguished from endogenous Epo mRNA by ribonuclease protection and competitive polymerase chain reaction. The basal expression and hypoxic induction of the marked Epo gene that had no deletions were indistinguishable from that of the endogenous Epo gene. Likewise, deletion of conserved intervening sequence 1 had minimal effect on hypoxic induction. In contrast, a 3'-deletion that included the conserved 3'-enhancer element resulted in a substantial, but not complete, suppression of hypoxic induction while a 3'-deletion downstream of the enhancer resulted in enhancement. A 188-base pair deletion of a conserved 3'-untranslated region in Exon 5 had minimal effect on hypoxic induction. However, the truncated Epo mRNA had a markedly prolonged half-life (15 h) in comparison to the endogenous Epo mRNA (2.0 h) or the marked full-length Epo mRNA (2.1 h). Further deletions in the 3'-UTR showed that a relatively small region of approximately 50 bases is responsible for the relatively rapid turnover of Epo mRNA. These experiments provide information on cis-acting elements of the Epo gene that cannot be obtained from conventional reporter gene transfection experiments.
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PMID:Use of a marked erythropoietin gene for investigation of its cis-acting elements. 773 Mar 12

Multiple alternatively spliced 5' untranslated regions (5'UTRs) have been identified in growth hormone (GH) receptor mRNA isolated from hepatic and adipocyte tissue. In the present study, the preferential utilisation of a GC-rich 5'UTR, designated exon 1B, was observed following the isolation of ovine (o) GH receptor cDNA clones from a skeletal muscle cDNA library. Although exon 1B-oGH receptor mRNA was expressed in all tissues examined, marked differences in the level of expression relative to the whole GH receptor transcript pool were observed between tissues. A single genomic clone (lambda 9) was isolated that encompassed exon 1B, together with 6 kilobase pairs of 5' and 12 kilobase pairs of 3' flanking sequence. Multiple transcription initiation sites were identified using RNase protection analysis on skeletal muscle poly(A)+ RNA, a result consistent with the absence of a proximal TATA box element. A CAAT box (-37 to -33) and a putative binding site for SP1 (a GC box -68 to -63) were found in the sense orientation immediately upstream of major transcription initiation site. Transfection of a series of overlapping promoter fragments linked to the luciferase reporter gene into HuH7, CHO and HeLa cells defined a core promoter element of 134 base pairs that was sufficient for maximum promoter activity. The emerging complexity of the 5' regulatory region of the GH receptor gene was emphasised by the observation that probes derived from exon 1B and the distal 3' intron boundary do not hybridise with previously cloned genomic sequences that span the liver-specific P1 promoter and exon 2.
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PMID:Differential expression of growth hormone receptor messenger RNA from a second promoter. 775 37

A statistically significant folding region is identified in the 5' untranslated region (5'-UTR) of hepatitis C virus (HCV), bovine viral diarrhea virus and hog cholera virus. This unusual folding region (UFR) detected in HCV encompasses 199 nucleotides (nt) and coincides with the reported internal ribosome entry site or ribosome landing pad (RLP), as determined by the 5' and 3' deletions [Tsukiyama-Kohara et al., J. Virol. 66 (1992) 1476-1483]. The RNA structure predicted in the UFR of HCV consists of a large stem-loop and a pseudoknot. The proposed structural model is consistent with RNase sensitivity studies [Brown et al., Nucleic Acids Res. 20 (1992) 5041-5045]. Moreover, the structure is highly conserved among these divergent HCV and pestivirus RNAs. The covariation of paired bases in the helical regions offers support for the proposed structural models. The pseudoknot predicted in these UFR shares a similar structural feature to those proposed in the RLP of cardioviruses, aphthoviruses and hepatitis A virus. Based on the common structural motif, a putative base-pairing model between HCV RNA and 18S rRNA, as well as pestiviral RNAs and 18S rRNA are suggested. Intriguingly, the proposed base-pairing models in this study are comparable to those proposed in picornaviruses in terms of their folded shape and location of the predicted complementary sequences between viral RNAs and 18S rRNA. Taken together, we suggest that the common base-pairing model between the UFR detected in the 5'-UTR of pestivirus and HCV and 18S rRNA have a general function in the internal initiation of cap-independent translation.
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PMID:Unusual folding regions and ribosome landing pad within hepatitis C virus and pestivirus RNAs. 789 Jan 55

The c-mos proto-oncogene product is a key element in the cascade of events leading to meiotic maturation of vertebrate oocytes. We have investigated the role of cytoplasmic polyadenylation in the translational control of mouse c-mos mRNA and its contribution to meiosis. Using an RNase protection assay we show that optimal cytoplasmic polyadenylation of c-mos mRNA requires three cis elements in the 3' UTR: the polyadenylation hexanucleotide AAUAAA and two U-rich cytoplasmic polyadenylation elements (CPEs) located 4 and 51 nucleotides upstream of the hexanucleotide. When fused to CAT coding sequences, the wild-type 3' UTR of c-mos mRNA, but not a 3' UTR containing mutations in both CPEs, confers translational recruitment during maturation. This recruitment coincides with maximum polyadenylation. To assess whether c-mos mRNA polyadenylation is necessary for maturation of mouse oocytes, we have ablated endogenous c-mos mRNA by injecting an antisense oligonucleotide, which results in a failure to progress to meiosis II after emission of the first polar body. Such antisense oligonucleotide-injected oocytes could be efficiently rescued by co-injection of a c-mos mRNA carrying a wild-type 3' UTR. However, co-injection of a c-mos mRNA lacking functional CPEs substantially lowered the rescue activity. These results demonstrate that translational control of c-mos mRNA by cytoplasmic polyadenylation is necessary for normal development.
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PMID:Translational control by cytoplasmic polyadenylation of c-mos mRNA is necessary for oocyte maturation in the mouse. 798 67

We report the functional and structural analysis of the 5' untranslated region (5'UTR) of human hepatoma HepG2 gamma-glutamyltransferase (GGT) mRNA. Transient expression of a hybrid GGT-luciferase gene in HepG2, MIA-Pa-Ca-2 and MG 63 cell lines shows that this 5'UTR acts as a tissue-specific translational enhancer. Evidence for transcripts with multiple 5'UTR coding for HepG2 GGT was obtained by RNase protection. Computer analysis of this 5'UTR detected the existence of a stable stem and loop structure containing multiple steroid modulatory elements.
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PMID:The 5' untranslated region of the human gamma-glutamyl transferase mRNA contains a tissue-specific active translational enhancer. 810 26

Gap junctions, membrane channels that mediate the diffusion of ions and small molecules between cells, are hypothesized to play a role in development and growth regulation. The Cx43 gene (encoding connexin 43) is one member of the gap junction gene family whose transcripts are expressed in a highly regionalized manner during mouse development. We cloned and sequenced Cx43 cDNAs from a 7.5-day mouse embryo cDNA library. These cDNA clones encode the authentic 43-kDa connexin. Analysis of RNA isolated from different regions of the 7.5-day mouse embryo revealed that Cx43 transcripts are differentially expressed, with expression detected in the embryo proper, but not in the extraembryonic region containing the ectoplacental cone. Using one of the newly isolated mouse Cx43 cDNA probes, we screened a mouse genomic DNA library and cloned the Cx43 gene. Restriction mapping and sequencing of the cloned genomic inserts revealed that Cx43 contains two exons and a 10.5-kb intron located in the 5' untranslated region (5'-UTR). We mapped the Cx43 transcription start point (tsp) by RNase protection and primer extension analyses and showed that transcripts expressed in the 7.5-day mouse embryo and in adult tissues are initiated from the same tsp. The DNA sequence immediately upstream from the tsp contains a putative AP1-binding site and a degenerate TATA consensus sequence. A comparison of mouse, rat, human and bovine Cx43s showed that the 3'-UTR has an unexpectedly high degree of sequence homology. This includes conservation of four AUUUA motifs, a sequence associated with transcript instability in immediate early genes.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Structure, sequence and expression of the mouse Cx43 gene encoding connexin 43. 839 50

Expression of class 3 aldehyde dehydrogenase (ALDH-3) is constitutive or inducible, depending on the tissue. ALDH-3 induction occurs both during neoplastic development and after exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). In order to study the regulation of ALDH-3 gene expression, ALDH-3 genomic sequences have been obtained from normal rat genomic DNA. Two overlapping genomic fragments (ALDH-UTR-1 and ALDH-NL2) contain the entire ALDH-3 gene along with considerable 5'- and 3'-flanking sequences. The rat ALDH-3 gene spans approximately 9 kilobases in length and consists of eleven exons; ten coding and one 5'-noncoding. The region 5' to exon one contains several putative transcription factor binding elements which may be important in the TCDD inducibility of this gene. These include a xenobiotic response element (XRE), a drug response element (DRE), LAP and Ap1 binding sites, and one Sp1 site. There are considerable differences in organization between the rat and human class 3 ALDH genes. Primer extension and RNase protection analysis indicate that both basal and TCDD-inducible expression of the ALDH-3 gene utilize the same multiple transcription start sites.
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PMID:Organization and characterization of the rat class 3 aldehyde dehydrogenase gene. 850 94


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