SEARCH · PubMed Health

Results for “Translational repression”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 343 records · Page 19Linked to original sources

PubMed1994

Translational control of arylsulfatase A expression in mouse testis.

Arylsulfatase A is a lysosomal enzyme that is involved in the degradation of sulfated glycolipids. High levels of arylsulfatase A mRNA are found in germ cells of mouse testis. In late pachytene and secondary spermatocytes the level of arylsulfatase A mRNA is increased 20-fold when compared with other tissues. These high levels of arylsulfatase A mRNA are maintained in round spermatids and decrease in late elongating spermatids. The increase of arylsulfatase A mRNA levels is not accompanied by a similar increase in enzyme activity or polypeptides. Subcellular fractionation revealed that the majority of arylsulfatase A mRNA is not associated with polysomes but is found in fractions of lower buoyancy. The failure to become translated is ascribed to the association of arylsulfatase A mRNA with nonpolysomal ribonucleoproteins. This translational repression may be due to proteins that bind to arylsulfatase A mRNA and prevent its translation. Within the 639-nucleotide 5'-untranslated region and the 700-nucleotide 3'-untranslated region of the arylsulfatase A mRNA, we identified two regions that specifically bind proteins present in extracts prepared from testicular cells. These RNA binding proteins were absent from extracts prepared from liver or brain.

Animals↗

PubMed1995

Localization of oskar RNA regulates oskar translation and requires Oskar protein.

The site of oskar RNA and protein localization within the oocyte determines where in the embryo primordial germ cells form and where the abdomen develops. Initiation of oskar RNA localization requires the activity of several genes. We show that ovaries mutant for any of these genes lack Oskar protein. Using various transgenic constructs we have determined that sequences required for oskar RNA localization and translational repression map to the oskar 3'UTR, while sequences involved in the correct temporal activation of translation reside outside the oskar 3'UTR. Upon localization of oskar RNA and protein at the posterior pole, Oskar protein is required to maintain localization of oskar RNA throughout oogenesis. Stable anchoring of a transgenic reporter RNA at the posterior pole is disrupted by oskar nonsense mutations. We propose that initially localization of oskar RNA permits translation into Oskar protein and that subsequently Oskar protein regulates its own RNA localization through a positive feedback mechanism.

Animals↗

PubMed2005

Crystal structure and functional analysis of DEAD-box protein Dhh1p.

The control of mRNA translation and degradation are critical for proper gene expression. A key regulator of both translation and degradation is Dhh1p, which is a DEAD-box protein, and functions both to repress translation and enhance decapping. We describe the crystal structure of the N- and C-terminal truncated Dhh1p (tDhh1p) determined at 2.1 A resolution. This reveals that, like other DEAD-box proteins, tDhh1p contains two RecA-like domains, although with a unique arrangement. In contrast to eIF4A and mjDEAD, in which no motif interactions exist, in Dhh1p, motif V interacts with motif I and the Q-motif, thereby linking the two domains together. Electrostatic potential mapping combined with mutagenesis reveals that motifs I, V, and VI are involved in RNA binding. In addition, trypsin digestion of tDhh1p suggests that ATP binding enhances an RNA-induced conformational change. Interestingly, some mutations located in the conserved motifs and at the interface between the two Dhh1 domains confer dominant negative phenotypes in vivo and disrupt the conformational switch in vitro. This suggests that this conformational change is required in Dhh1 function and identifies key residues involved in that transition.

Amino Acid Sequence↗

PubMed2026

Pseudogene-Derived Long Noncoding RNAs GSTM3P1/Gstm2-ps1 Exacerbate Sepsis-Associated Acute Kidney Injury by Suppressing Their Parent Gene Translation.

Long noncoding RNAs are emerging as critical regulators of acute kidney injury (AKI). In this study, the pathologic role of pseudogene-derived long noncoding RNAs GSTM3P1 (human)/Gstm2-ps1 (mouse) in sepsis-associated AKI (SA-AKI) was investigated. Glutathione S-transferase mu 3, pseudogene 1 (GSTM3P1)/glutathione S-transferase mu 2, pseudogene 1 (Gstm2-ps1) were transiently up-regulated in kidney proximal tubular cells at the early stage of SA-AKI in mice treated with lipopolysaccharide (LPS) or cecal ligation and puncture, as well as in LPS-treated proximal tubular cells. Functionally, overexpression of GSTM3P1/Gstm2-ps1 exacerbated LPS-induced proximal tubular cell apoptosis and oxidative stress. In contrast, proximal tubule-specific Gstm2-ps1 knockout mice were significantly protected from LPS-induced AKI, as evidenced by improved renal function and reduced apoptosis, kidney injury markers, and reactive oxygen species. Similarly, these mice showed renal protective effects against cecal ligation and puncture-induced AKI. Mechanistically, overexpression of GSTM3P1/Gstm2-ps1 in proximal tubular cells markedly suppressed parent gene GSTM3/GSTM2 protein but not mRNA expression, indicating a translational repression. Restoration of GSTM3/GSTM2 rescued proximal tubular cells from LPS-induced apoptosis. Furthermore, an RNA pulldown assay revealed that Gstm2-ps1 binds to human antigen R (HuR), a known post-transcriptional regulator for mRNA stability and translation. Overexpression of HuR antagonized Gstm2-ps1-mediated repression of GSTM2, associated with increased cell survival after LPS injury. In conclusion, the early induction of GSTM3P1/Gstm2-ps1 in SA-AKI exacerbates kidney injury by a novel mechanism to sequester HuR and inhibit the translation of parent gene GSTM3/gstm2 for oxidative stress detoxification.

Animals↗

PubMed1990

Binding of the bacteriophage T4 regA protein to mRNA targets: an initiator AUG is required.

Bacteriophage T4 regA protein translationally represses the synthesis of a subset of early phage-induced proteins. The protein binds to the translation initiation site of at least two mRNAs and prevents formation of the initiation complex. We show here that the protein binds to the translation initiation sites of other regA-sensitive mRNAs. Analysis of mRNA binding by filtration and nuclease protection assays shows that AUG is necessary but not sufficient for specific binding of regA protein to its mRNA targets. Anticipating the need for large quantities of regA protein for structural studies to further define the regA protein-RNA ligand interaction, we also report cloning the regA gene into a T4 overexpression system. The expression of regA protein in uninfected E. coli is lethal, so in our system regA driven by a strong T7 promoter is sequestered in a T4 phage until 'induction' by phage infection is desired. We have replaced the regA sensitive wild-type ribosome binding site with a strong insensitive ribosome binding site at an optimal distance from the regA initiation codon for maximizing expression. We have obtained large amounts of regA protein.

Base Sequence↗

PubMed2006

mRNA degradation by miRNAs and GW182 requires both CCR4:NOT deadenylase and DCP1:DCP2 decapping complexes.

MicroRNAs (miRNAs) silence the expression of target genes post-transcriptionally. Their function is mediated by the Argonaute proteins (AGOs), which colocalize to P-bodies with mRNA degradation enzymes. Mammalian P-bodies are also marked by the GW182 protein, which interacts with the AGOs and is required for miRNA function. We show that depletion of GW182 leads to changes in mRNA expression profiles strikingly similar to those observed in cells depleted of the essential Drosophila miRNA effector AGO1, indicating that GW182 functions in the miRNA pathway. When GW182 is bound to a reporter transcript, it silences its expression, bypassing the requirement for AGO1. Silencing by GW182 is effected by changes in protein expression and mRNA stability. Similarly, miRNAs silence gene expression by repressing protein expression and/or by promoting mRNA decay, and both mechanisms require GW182. mRNA degradation, but not translational repression, by GW182 or miRNAs is inhibited in cells depleted of CAF1, NOT1, or the decapping DCP1:DCP2 complex. We further show that the N-terminal GW repeats of GW182 interact with the PIWI domain of AGO1. Our findings indicate that GW182 links the miRNA pathway to mRNA degradation by interacting with AGO1 and promoting decay of at least a subset of miRNA targets.

Amino Acid Sequence↗

PubMed2005

Adenosine augments IL-10 production by macrophages through an A2B receptor-mediated posttranscriptional mechanism.

Adenosine receptor ligands have anti-inflammatory effects and modulate immune responses by up-regulating IL-10 production by immunostimulated macrophages. The adenosine receptor family comprises G protein-coupled heptahelical transmembrane receptors classified into four types: A1, A2A, A2B, and A3. Our understanding of the signaling mechanisms leading to enhanced IL-10 production following adenosine receptor occupancy on macrophages is limited. In this study, we demonstrate that adenosine receptor occupancy increases IL-10 production by LPS-stimulated macrophages without affecting IL-10 promoter activity and IL-10 mRNA levels, indicating a posttranscriptional mechanism. Transfection experiments with reporter constructs containing sequences corresponding to the AU-rich 3'-untranslated region (UTR) of IL-10 mRNA confirmed that adenosine receptor activation acts by relieving the translational repressive effect of the IL-10 3'-UTR. By contrast, adenosine receptor activation failed to liberate the translational arrest conferred by the 3'-UTR of TNF-alpha mRNA. The IL-10 3'-UTR formed specific complexes with proteins present in cytoplasmic extracts of RAW 264.7 cells. Adenosine enhanced binding of proteins to a region of the IL-10 3'-UTR containing the GUAUUUAUU nonamer. The stimulatory effect of adenosine on IL-10 production was mediated through the A(2B) receptor, because the order of potency of selective agonists was 5'-N-ethylcarboxamidoadenosine (NECA) > N6-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (IB-MECA) > 2-chloro-N6-cyclopentyladenosine (CCPA) = 2-p-(2-carboxyethyl)phenethylamino-5'-N-ethyl-carboxamidoadenosine (CGS-21680). Also, the selective A2B antagonist, alloxazine, prevented the effect of adenosine. Collectively, these studies identify a novel pathway in which activation of a G protein-coupled receptor augments translation of an anti-inflammatory gene.

3' Untranslated Regions↗

PubMed2006

Endogenous inhibitory cytokines repress TNFalpha secretion.

Tumor necrosis factor alpha (TNFalpha), with the potential to destroy tissue, is likely to be tightly regulated. A major regulatory step is the translational repression of TNFalpha. This study evaluates whether endogenous inhibitory cytokines account for this repression. Two cell populations were isolated from peripheral blood using techniques that minimized activation, one composed primarily of monocytes and the other containing T-cells and NK-cells. When cultured without a stimulus in the presence of Abs neutralizing IL-4, IL-10, or TGFbeta, each population released large amounts of TNFalpha, reaching levels induced by PHA or LPS. Their actions were at the post-translational level since the numbers of transcripts did not change, and inhibitors of protein or RNA synthesis had no effects. When inhibitors of 38 MAP kinase and ERK were added, T-cell release of TNFalpha proved to involve both pathways while monocytes were dependent on p38 but not ERK. Changes in soluble TNF receptor levels or cell uptake of TNFalpha were not involved. This study shows that low TNFalpha secretion by resting T-cells and monocytes is maintained by endogenous inhibitors that suppress post-translational processing of TNFalpha by MAP kinases. Keeping TNFalpha levels low is critical to the non-inflammatory steady-state.

Cytokines↗

PubMed2002

A regulatory cytoplasmic poly(A) polymerase in Caenorhabditis elegans.

Messenger RNA regulation is a critical mode of controlling gene expression. Regulation of mRNA stability and translation is linked to controls of poly(A) tail length. Poly(A) lengthening can stabilize and translationally activate mRNAs, whereas poly(A) removal can trigger degradation and translational repression. Germline granules (for example, polar granules in flies, P granules in worms) are ribonucleoprotein particles implicated in translational control. Here we report that the Caenorhabditis elegans gene gld-2, a regulator of mitosis/meiosis decision and other germline events, encodes the catalytic moiety of a cytoplasmic poly(A) polymerase (PAP) that is associated with P granules in early embryos. Importantly, the GLD-2 protein sequence has diverged substantially from that of conventional eukaryotic PAPs, and lacks a recognizable RRM (RNA recognition motif)-like domain. GLD-2 has little PAP activity on its own, but is stimulated in vitro by GLD-3. GLD-3 is also a developmental regulator, and belongs to the Bicaudal-C family of RNA binding proteins. We suggest that GLD-2 is the prototype for a class of regulatory cytoplasmic PAPs that are recruited to specific mRNAs by a binding partner, thereby targeting those mRNAs for polyadenylation and increased expression.

Amino Acid Sequence↗

PubMed1998

Gastrin induces phosphorylation of eIF4E binding protein 1 and translation initiation of ornithine decarboxylase mRNA.

Gastrin via its G-protein coupled specific receptor induces transcription of c-fos and c-jun genes through a ras-MAPK pathway. Ornithine Decarboxylase (ODC), a growth regulated proto-oncogene, was chosen to investigate gastrin effects on translation initiation of mRNAs exhibiting a 5'UnTranslated Region (5'UTR) responsible for translation repression in quiescent cells. In AR4-2J tumoral cells, we first demonstrated that gastrin increases ODC mRNA translation. Transient transfections with various CAT chimeric constructs suggested a direct involvement of the 5'UTR in this observation. Translation of this group of mRNAs is enhanced by the availability of the cap-binding protein (eIF4E) that is increased after phosphorylation of its specific binding protein eIF4E-BP1. We found that AR4-2J cells over-expressed eIF4E protein which was not modulated by gastrin treatment. Rapamycin which inhibits 4E-BP1 phosphorylation, completely prevents gastrin-mediated increase of ODC translation indicating that 4E-BP1 could be involved in regulating ODC translation. Implication of 4E-BP1 in mediating gastrin effects is corroborated by the capacity of the ligand to affect 4E-BP1 phosphorylation. These results indicate that gastrin enhances ornithine decarboxylase mRNA translation through a rapamycin sensitive pathway and provide the first evidence in the control of 4E-BP1 phosphorylation after occupancy of a G protein-coupled receptor.

Animals↗

PubMed2001

Biochemical identification of Xenopus Pumilio as a sequence-specific cyclin B1 mRNA-binding protein that physically interacts with a Nanos homolog, Xcat-2, and a cytoplasmic polyadenylation element-binding protein.

Translational activation of dormant cyclin B1 mRNA stored in oocytes is a prerequisite for the initiation or promotion of oocyte maturation in many vertebrates. Using a monoclonal antibody against the domain highly homologous to that of Drosophila Pumilio, we have shown for the first time in any vertebrate that a homolog of Pumilio is expressed in Xenopus oocytes. This 137-kDa protein binds to the region including the sequence UGUA at nucleotides 1335-1338 in the 3'-untranslated region of cyclin B1 mRNA, which is close to but does not overlap the cytoplasmic polyadenylation elements (CPEs). Physical in vitro association of Xenopus Pumilio with a Xenopus homolog of Nanos (Xcat-2) was demonstrated by a protein pull-down assay. The results of immunoprecipitation experiments showed in vivo interaction between Xenopus Pumilio and CPE-binding protein (CPEB), a key regulator of translational repression and activation of mRNAs stored in oocytes. This evidence provides a new insight into the mechanism of translational regulation through the 3'-end of mRNA during oocyte maturation. These results also suggest the generality of the function of Pumilio as a translational regulator of dormant mRNAs in both invertebrates and vertebrates.

3' Untranslated Regions↗

PubMed2004

Translational control of beta2-adrenergic receptor mRNA by T-cell-restricted intracellular antigen-related protein.

Cellular expression of the beta(2)-adrenergic receptor (beta(2)-AR) is suppressed at the translational level by 3'-untranslated region (UTR) sequences. To test the possible role of 3'-UTR-binding proteins in translational suppression of beta(2)-AR mRNA, we expressed the full-length 3'-UTR or the adenylate/uridylate-rich (A+U-rich element (ARE)) RNA from the 3'-UTR sequences of beta(2)-AR in cell lines that endogenously express this receptor. Reversal of beta(2)-adrenergic receptor translational repression by retroviral expression of 3'-UTR sequences suggested that ARE RNA-binding proteins are involved in translational suppression of beta(2)-adrenergic receptor expression. Using a 20-nucleotide ARE RNA from the receptor 3'-UTR as an affinity ligand, we purified the proteins that bind to these sequences. T-cell-restricted intracellular antigen-related protein (TIAR) was one of the strongly bound proteins identified by this method. UV-catalyzed cross-linking experiments using in vitro transcribed 3'-UTR RNA and glutathione S-transferase-TIAR demonstrated multiple binding sites for this protein on beta(2)-AR 3'-UTR sequences. The distal 340-nucleotide region of the 3'-UTR was identified as a target RNA motif for TIAR binding by both RNA gel shift analysis and immunoprecipitation experiments. Overexpression of TIAR resulted in suppression of receptor protein synthesis and a significant shift in endogenously expressed beta(2)-AR mRNA toward low molecular weight fractions in sucrose gradient polysome fractionation. Taken together, our results provide the first evidence for translational control of beta(2)-AR mRNA by TIAR.

3' Untranslated Regions↗

PubMed2001

The 5' UTR of protein kinase C epsilon confers translational regulation in vitro and in vivo.

We have examined translational regulation conferred by the 5' untranslated region (UTR) of PKCepsilon on expression of the luciferase reporter gene in vitro, using rabbit reticulocyte lysates and in vivo, in contact-inhibiting mouse Swiss 3T3 fibroblasts and non-contact-inhibiting Swiss 3T6 fibroblasts. In rabbit reticulocyte lysates, the 5' UTR of PKCepsilon significantly represses translation. In 3T3 and 3T6 cells, the 5' UTR of PKCepsilon reduces luciferase activity, but not to the same extent as it does in vitro. In rabbit reticulocyte lysate, the degree of repression mediated by different PKCepsilon 5' UTR-deletion constructs correlates with the free energy (DeltaG) of their predicted secondary structures. However, in cells, secondary structure is not the only determinant of repression; an internal region of the 5' UTR is both necessary and sufficient for repression. Mutation of an upstream AUG (uAUG) motif in this region partially relieves repression. We conclude that the 5' UTR of PKCepsilon can mediate translational regulation and that translation inhibition in vivo involves the uAUG motif. Our findings also suggest that there are factors present in fibroblasts, but not in rabbit reticulocyte lysates that substantially overcome the repressive qualities of the long, structured 5' UTR. Thus, we have identified a potential new level of regulation of PKC in mammalian cells.

3T3 Cells↗

PubMed2003

siRNAs can function as miRNAs.

With the discovery of RNA interference (RNAi) and related phenomena, new regulatory roles attributed to RNA continue to emerge. Here we show, in mammalian tissue culture, that a short interfering RNA (siRNA) can repress expression of a target mRNA with partially complementary binding sites in its 3' UTR, much like the demonstrated function of endogenously encoded microRNAs (miRNAs). The mechanism for this repression is cooperative, distinct from the catalytic mechanism of mRNA cleavage by siRNAs. The use of siRNAs to study translational repression holds promise for dissecting the sequence and structural determinants and general mechanism of gene repression by miRNAs.

3' Untranslated Regions↗

PubMed2004

The oligo(A) tail on histone mRNA plays an active role in translational silencing of histone mRNA during Xenopus oogenesis.

Metazoan replication-dependent histone mRNAs end in a stem-loop sequence. The one known exception is the histone mRNA in amphibian oocytes, which has a short oligo(A) tail attached to the stem-loop sequence. Amphibian oocytes also contain two proteins that bind the 3' end of histone mRNA: xSLBP1, the homologue of the mammalian SLBP, and xSLBP2, which is present only in oocytes. xSLBP2 is an inhibitor of histone mRNA translation, while xSLBP1 activates translation. The short A tail on histone mRNAs appears at stage II to III of oogenesis and is present on histone mRNAs throughout the rest of oogenesis. At oocyte maturation, the oligo(A) tail is removed and the xSLBP2 is degraded, resulting in the activation of translation of histone mRNA. Both SLBPs bind to the stem-loop with the oligo(A) tail with similar affinities. Reporter mRNAs ending in the stem-loop with or without the oligo(A) tail are translated equally well in a reticulocyte lysate, and their translation is stimulated by the presence of xSLBP1. In contrast, translation of the reporter mRNA with an oligo(A) tail is not activated in frog oocytes in response to the presence of xSLBP1. These results suggest that the oligo(A) tail is an active part of the translation repression mechanism that silences histone mRNA during oogenesis and that its removal is part of the mechanism that activates translation.

Adenine Nucleotides↗

PubMed1994

Translation of 15-lipoxygenase mRNA is inhibited by a protein that binds to a repeated sequence in the 3' untranslated region.

During red blood cell differentiation, the mRNA encoding rabbit erythroid 15-lipoxygenase (LOX) is synthesized in the early stages of erythropoiesis, but is only activated for translation in peripheral reticulocytes. Erythroid LOX, which like other lipoxygenases catalyses the degradation of lipids, is unique in its ability to attack intact phospholipids and is the main factor responsible for the degradation of mitochondria during reticulocyte maturation. Strikingly, rabbit erythroid LOX mRNA has 10 tandem repeats of a slightly varied, pyrimidine-rich 19 nt motif in its 3'-untranslated region (3'-UTR). In this study we demonstrate, using gel retardation and UV-crosslinking assays, that this 3'-UTR segment specifically binds a 48 kDa reticulocyte protein. Furthermore, the interaction between the 3'-UTR LOX repeat motif and the 48 kDa protein, purified to homogeneity by specific RNA chromatography, is shown to be necessary and sufficient for specific translational repression of LOX as well as reporter mRNAs in vitro. To our knowledge this is the first case in which translation, presumably at the initiation step, is regulated by a defined protein-RNA interaction in the 3'-UTR.

Animals↗

PubMed1994

Poly(A) tail shortening of alpha-amylase mRNAs in vegetative tissues of Oryza sativa.

The pattern of expression for the entire alpha-amylase gene family in rice vegetative tissues during the developmental growth stages has been studied. We were surprised that the size of rice alpha-amylase mRNAs in the young roots, shoots, and different tissues from adult plant was shorter by approximately 250 bases than that in immature or mature embryos and aleurone layers of seed. Interestingly, the difference in the size of the alpha-amylase mRNAs of rice seed and vegetative tissues is due to the variation in the length of the 3'-poly(A) tracts. In addition, if without glycogen-precipitated treatment for alpha-amylase purification, no alpha-amylases can be detected in vegetative tissues by Western blot analysis. Furthermore, in vitro translation assay revealed that alpha-amylase mRNAs receiving shortened poly(A) tracts in vegetative tissues become translationally repressed. These results indicate that the 3'-poly(A) tract of eukaryotic mRNAs plays an important role in controlling mRNA translatability.

Blotting, Northern↗

PubMed1992

An internal region of rpoB is required for autogenous translational regulation of the beta subunit of Escherichia coli RNA polymerase.

In order to delineate the region involved in feedback regulation of the RNA polymerase beta subunit (encoded by rpoB), a collection of rpoB-lacZ translational fusions with different endpoints both upstream and downstream of the rpoB start site was assembled on lambda phage vectors. The extent of translational repression of beta was monitored by measuring beta-galactosidase levels in monolysogens of the fusions under conditions of increased intracellular concentrations of beta and beta' achieved via the induction of rpoBC expression from a multicopy plasmid. A construct containing as little as 29 bp upstream of the start of rpoB exhibited repression of beta-galactosidase activity to the same extent as a construct encoding the full upstream region. A construct which carried only 70 bp of the rpoB structural gene exhibited very little repression, while constructs which carried 126 or 221 bp of rpoB exhibited approximately the same degree of repression as a construct which carried 403 bp. These data suggest that the sequences important for feedback regulation of beta translation extend more than 70 bp into rpoB but are completely contained within a region which spans the sequences from 29 bp upstream to 126 bp downstream of the translational start site.

Bacteriophage lambda↗