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Results for “Translational control”

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PubMed2003

Bacterial translational control at atomic resolution.

Translational regulation allows rapid adaptation of protein synthesis to environmental conditions. In prokaryotes, the synthesis of many RNA-binding proteins is regulated by a translational feedback mechanism involving a competition between their natural substrate and their binding site on mRNA, which are often thought to resemble each other. This article describes the case of threonyl-tRNA synthetase, which represses the translation of its own mRNA. Recent data provide the first opportunity to describe at the atomic level both the extent and the limit of mimicry between the way this enzyme recognizes tRNA(Thr) and its regulatory site in mRNA. The data also give some clues about how the binding of the synthetase to its mRNA inhibits translation.

Base Sequence↗

PubMed1975

Evidence supporting a physiological role for the hemin-controlled translational repressor of globin synthesis in reticulocytes.

The synthesis of heme and globin in rabbit reticulocytes was compared at 35 and 25 degrees C. The lower temperature decreased heme synthesis significantly more than globin synthesis and resulted in a much greater accumulation of globin dimers. After 16 h of incubation in the absence of iron, globin synthesis in reticulocytes which were at 35 degrees C could not be stimulated by iron, whereas cells which were at 25 degrees C responded with nearly control levels of globin synthesis. Since the formation of the hemin-controlled translational repressor in reticulocyte lysates is also decreased much more than protein synthesis at reduced temperature the results provide evidence for a physiological role for the translational repressor in controlling globin synthesis in reticulocytes.

Animals↗

PubMed1990

Translational control of ribosomal protein production in mammalian cells.

Mammalian ribosomal protein (rp) mRNAs are subject to translational control, as illustrated by their selective release from polyribosomes in growth-arrested cells and their under-representation in polyribosomes of normally growing cells. Recent studies have localized the translational regulatory element to the 5' end of the rp mRNA and have demonstrated that an oligopyrimidine tract, which adjoins the cap structure in all known vertebrate rp mRNAs, is an essential part of this element. Possible factors that might interact with the oligopyrimidine tract are discussed.

Animals↗

PubMed1991

The 5'-untranslated region of p23 mRNA from the Ehrlich ascites tumor is involved in translation control of the growth related protein p23.

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.

Animals↗

PubMed2001

Immunoprecipitation of [(3)H]dihydroartemisinin translationally controlled tumor protein (TCTP) adducts from Plasmodium falciparum-infected erythrocytes by using anti-TCTP antibodies.

Artemisinin and its derivatives are endoperoxide-containing antimalarial drugs that appear to form adducts in situ with the Plasmodium falciparum translationally controlled tumor protein (TCTP) homolog. Immunoprecipitation with antibody to recombinant TCTP suggests that adducts may form with both monomeric and dimeric TCTP.

Animals↗

PubMed2004

Translationally controlled tumor protein is a target of tumor reversion.

By analyzing the gene expression profile between tumor cells and revertant counterparts that have a suppressed malignant phenotype, we previously reported a significant down-regulation of translationally controlled tumor protein (TCTP) in the revertants. In the present study, we derived, by using the H1 parvovirus as a selective agent, revertants from three major solid cancers: colon, lung, and melanoma cell lines. These cells have a strongly suppressed malignant phenotype both in vitro and in vivo. The level of TCTP is decreased in most of the revertants. To verify whether inhibition of TCTP expression induces changes in the malignant phenotype, in the classical, well established model of "flat reversion," v-src-transformed NIH3T3 cells were transfected with antisense TCTP. By inhibiting the expression of TCTP, the number of revertant cells was raised to 30%, instead of the reported rate for spontaneous flat revertants of 10(-6). Because TCTP encodes for a histamine-releasing factor, we tested the hypothesis that inhibitors of the histaminic pathway could be effective against tumor cells. We show that some antihistaminic compounds (hydroxyzine and promethazine) and other pharmacological compounds with a related structure (including thioridazine and sertraline) kill tumor cells and significantly decrease the level of TCTP. All together, these data suggest that, with tumor reversion used as a working model, TCTP was identified as a target and drugs were selected that decrease its expression and kill tumor cells.

Animals↗

PubMed2004

cDNA cloning of translationally controlled tumor protein/histamine releasing factor (TCTP/HRF) from the intertidal harpacticoid copepod Tigriopus japonicus.

We synthesized a cDNA library from the intertidal copepod Tigriopus japonicus, converted it to phagemids and sequenced expressed sequence tags (ESTs). Of these, Tigriopus translationally controlled tumor protein/histamine releasing factor (TCTP/HRF) was further characterized. The Tigriopus TCTP/HRF gene encoded 172 amino acid residues and showed high similarity to Drosophila but moderate similarity to other annelids (e.g. Brugia, Wuchereria and C. elegans). The Tigriopus TCTP/HRF gene appeared in the same clade as the annelids. Here, we describe the analysis of the Tigriopus TCTP/HRF gene.

Amino Acid Sequence↗

PubMed1999

From factors to mechanisms: translation and translational control in eukaryotes.

Biochemical and genetic studies are revealing a network of interactions between eukaryotic translation initiation factors, further refining or redefining perceptions of their function. The notion of translated mRNA as a 'closed-loop' has gained support from the identification of physical and functional interactions between the two mRNA ends and their associated factors. Translational control mechanisms are beginning to unravel in sufficient detail to pinpoint the affected step in the initiation pathway.

Eukaryotic Cells↗

PubMed1990

Translational control in influenza virus-infected cells.

Influenza virus type A has been shown to establish a translational control system such that during infection there is a dramatic inhibition of host cell protein synthesis and viral mRNAs are selectively and efficiently translated. The following review summarizes the complex strategies employed by influenza to accomplish these goals. These include: (i) preventing newly made cellular mRNAs from entering the cytoplasm of infected cells; (ii) inhibiting the initiation and elongation steps of translation of preexisting cellular mRNAs; (iii) possessing RNAs with structural features which enhance translation; (iv) encoding mechanisms to downregulate the interferon induced protein kinase thus allowing overall protein synthesis levels to remain high.

Animals↗

PubMed2003

The power of the 3' UTR: translational control and development.

Many crucial decisions, such as the location and timing of cell division, cell-fate determination, and embryonic axes establishment, are made in the early embryo, a time in development when there is often little or no transcription. For this reason, the control of variation in gene expression in the early embryo often relies on post-transcriptional control of maternal genes. Although the early embryo is rife with translational control, controlling mRNA activity is also important in other developmental processes, such as stem-cell proliferation, sex determination, neurogenesis and erythropoiesis.

3' Untranslated Regions↗

PubMed1984

Translational control during early Dictyostelium development: possible involvement of poly(A) sequences.

A rapid decrease in the translational efficiency of mRNA synthesized during vegetative growth is associated with the initiation of development in Dictyostelium discoideum. In contrast, newly synthesized mRNA associates with polysomes with high efficiency. Discrimination between these two mRNA populations correlates with a rapid shortening of the poly(A) tract on the preexisting mRNA. A model is proposed in which a critical poly(A) length regulates the pattern of protein synthesis by affecting the efficiency with which mRNAs can interact with the translational machinery. The model suggests that transcriptional and translational controls can be coupled by altering the state of adenylation of the preexisting mRNA population. The model allows radical changes in the pattern of protein synthesis without wholesale destruction of preexisting mRNA.

Base Sequence↗

PubMed1999

The Plasmodium falciparum translationally controlled tumor protein: subcellular localization and calcium binding.

Artemisinin derivatives are endoperoxide antimalarials widely used to treat falciparum malaria in areas where drug resistance is common. In Plasmodium falciparum-infected erythrocytes, radiolabeled artemisinin derivatives have been shown to react with malarial proteins, one of which is the Translationally Controlled Tumor Protein (TCTP). The P. falciparum TCTP was found by immunofluorescence to be located in both the cytoplasm and food vacuoles. Immunoelectron microscopy shows that it is present in the parasite cytoplasm as well as in its food vacuolar and limiting membranes. Like other TCTPs, the P. falciparum protein binds to calcium. Further studies on the physiological role of TCTP may aid in understanding the mechanism of action of endoperoxide antimalarials.

Animals↗

PubMed2005

An N-terminal region of translationally controlled tumor protein is required for its antiapoptotic activity.

Bcl-xL plays a critical role in maintaining cell survival. However, the relationship between the potential interaction of Bcl-xL with other cytosolic proteins and the regulation of cell survival remains incompletely defined. We have identified translationally controlled tumor protein (TCTP), a multifunctional protein, as a novel antiapoptotic Bcl-xL-interacting protein. TCTP interacted in vivo and in vitro with Bcl-xL, and their sites have been mapped to an N-terminal region of TCTP and the Bcl-2 homology domain 3 of Bcl-xL. Consistent with a role in maintaining T-cell survival during activation, TCTP was significantly upregulated in murine T cells activated by T-cell antigen receptor (TCR) ligation and CD28 costimulation, which was correlated with the upregulation of Bcl-xL in activated T cells. Moreover, downregulation of TCTP expression by antisense technology in T cells results in the increase of T-cell apoptosis. Furthermore, the N-terminal region of TCTP was required for its ability to inhibit apoptosis. In conclusion, this study has demonstrated that an N-terminal region of a cytosolic protein, TCTP, is required for its binding to Bcl-xL and for its antiapoptotic activity.

Amino Acid Sequence↗

PubMed1981

Translational control in lysates of Drosophila melanogaster cells.

Cell-free protein-synthesizing systems made from Drosophila melanogaster cells were used to study the translational control induced in these cells by heat shock. Lysates of normally growing cells, termed 25 degrees C cells, translate both normal and heat shock mRNAs. Lysates of cells heat shocked at 36 degrees C for 1 hr, termed 36 degrees C cells, translate preferentially heat-shock mRNAs and a few 25 degrees C cell mRNAs. Thus, both lysates appear to reproduce the control displayed in vivo. Both lysates are optimally active at 28 degrees C, and all translations are done at that temperature, demonstrating that, once established, the discrimination system does not require heat-shock temperature for its activity. Addition of crude ribosome fractions from 25 degrees C cell lysates to lysates from heat-shocked cells "rescues" translation of 25 degrees C cell mRNA, which suggests that the discriminating elements are associated with ribosomes. Neither the heat-shock crude ribosome supplements nor the soluble fractions have any effect on either lysate. The experiments also show that RNA selection is determined by some feature of the RNA structure that is insensitive to protease digestion and phenol/chloroform extraction. The essential structural feature may not be unique to Drosophila mRNAs because the Drosophila lysate is capable of discriminating among mRNAs from other organisms.

Actins↗

PubMed1998

The Plasmodium falciparum translationally controlled tumor protein homolog and its reaction with the antimalarial drug artemisinin.

Artemisinin and its derivatives are important new antimalarial drugs. When Plasmodium falciparum-infected erythrocytes are incubated with [10-3H]dihydroartemisinin, several malaria-specific proteins become labeled. One of these proteins is the P. falciparum translationally controlled tumor protein (TCTP) homolog. In vitro, dihydroartemisinin reacts covalently with recombinant TCTP in the presence of hemin. The association between drug and protein increases with increasing drug concentration, plateauing at approximately 1 drug/TCTP molecule. By Scatchard analysis, there appear to be 2 hemin binding sites on TCTP with dissociation constants of approximately 18 microM. When the single cysteine moiety is blocked by pretreatment with iodoacetamide, hemin binding is not affected, whereas drug binding is reduced by two-thirds. Thus, TCTP reacts with artemisinin in situ and in vitro in the presence of hemin and appears to bind to hemin. The function of the malarial TCTP and the role of this reaction in the mechanism of action of artemisinin await elucidation.

Amino Acid Sequence↗

PubMed1975

A new aspect of the RNA bacteriophages translation control mechanism.

The polarity effect of the coat protein gene of the ribonucleic acid of RNA bacteriophages on the polymerase gene translation will be taken as the basis of the polymerase translation control mechanism. A further condition for this mechanism discussed in this work is the dependence of the phage RNA replication on host cell translation factors. The ribosome binding sites of the phage RNA play a decisive role to realize the control mechanism coding for definite ribosome binding probabilities. The relation between them quantifies the reached polymerase concentration in the early phase of the development of the RNA bacteriophage system in the infected cell.

Bacteriophages↗

PubMed1988

Cis-acting regions sufficient for spermatocyte-specific transcriptional and spermatid-specific translational control of the Drosophila melanogaster gene mst(3)gl-9.

In Drosophila spermatogenesis transcription occurs only premeiotically while translation can be detected also in postmeiotic spermatids. To analyse the underlying processes mst(3)gl-9, a gene specifically expressed in the male germ cells of Drosophila melanogaster, was studied. The putative protein encoded by mst(3)gl-9 is mostly composed of repetitive Cys-Gly-Pro motifs. The transcriptional and translational control of expression of mst(3)gl-9 has been investigated by P-mediated transformation. Only 102 bp of 5' upstream sequences and the first 201 bp of the gene are sufficient to maintain the gene specific characteristics of expression, namely premeiotic transcription and postmeiotic translation separated by 3 days of development.

Amino Acid Sequence↗

PubMed2006

Translational control of collagen prolyl 4-hydroxylase-alpha(I) gene expression under hypoxia.

Hypoxia is a pro-fibrotic stimulus, which is associated with enhanced collagen synthesis, as well as with augmented collagen prolyl 4-hydroxylase (C-P4H) activity. C-P4H activity is controlled mainly by regulated expression of the alpha C-P4H subunit. In this study we demonstrate that the increased synthesis of C-P4H-alpha(I) protein in human HT1080 fibroblasts under long term hypoxia (36 h, 1% oxygen) is controlled at the translational level. This is mediated by an interaction of RNA-binding protein nucleolin (approximately 64 kDa form) at the 5'- and 3'-untranslated regions (UTR) of the mRNA. The 5'/3'-UTR-dependent mechanism elevates the C-P4H-alpha(I) expression rate 2.3-fold, and participates in a 5.3-fold increased protein level under long term hypoxia. The interaction of nucleolin at the 5'-UTR occurs directly and depends on the existence of an AU-rich element. Statistical evaluation of the approximately 64-kDa nucleolin/RNA interaction studies revealed a core binding sequence, corresponding to UAAAUC or AAAUCU. At the 3'-UTR, nucleolin assembles indirectly via protein/protein interaction, with the help of another 3'-UTR-binding protein, presumably annexin A2. The increased protein level of the approximately 64-kDa nucleolin under hypoxia can be attributed to an autocatalytic cleavage of a high molecular weight nucleolin form, without alterations in nucleolin mRNA concentration. Thus, the alteration of translational efficiency by nucleolin, which occurs through a hypoxia inducible factor independent pathway, is an important step in C-P4H-alpha(I) regulation under hypoxia.

3' Untranslated Regions↗