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1
Keiler, Kenneth C. "Biology oftrans-Translation". Annual Review of Microbiology 62, nr 1 (październik 2008): 133–51. http://dx.doi.org/10.1146/annurev.micro.62.081307.162948.
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Windgassen, Merle, Dorothée Sturm, Iván J. Cajigas, Carlos I. González, Matthias Seedorf, Holger Bastians i Heike Krebber. "Yeast Shuttling SR Proteins Npl3p, Gbp2p, and Hrb1p Are Part of the Translating mRNPs, and Npl3p Can Function as a Translational Repressor". Molecular and Cellular Biology 24, nr 23 (1.12.2004): 10479–91. http://dx.doi.org/10.1128/mcb.24.23.10479-10491.2004.
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ABSTRACT A major challenge in current molecular biology is to understand how sequential steps in gene expression are coupled. Recently, much attention has been focused on the linkage of transcription, processing, and mRNA export. Here we describe the cytoplasmic rearrangement for shuttling mRNA binding proteins in Saccharomyces cerevisiae during translation. While the bulk of Hrp1p, Nab2p, or Mex67p is not associated with polysome containing mRNAs, significant amounts of the serine/arginine (SR)-type shuttling mRNA binding proteins Npl3p, Gbp2p, and Hrb1p remain associated with the mRNA-protein complex during translation. Interestingly, a prolonged association of Npl3p with polysome containing mRNAs results in translational defects, indicating that Npl3p can function as a negative translational regulator. Consistent with this idea, a mutation in NPL3 that slows down translation suppresses growth defects caused by the presence of translation inhibitors or a mutation in eIF5A. Moreover, using sucrose density gradient analysis, we provide evidence that the import receptor Mtr10p, but not the SR protein kinase Sky1p, is involved in the timely regulated release of Npl3p from polysome-associated mRNAs. Together, these data shed light onto the transformation of an exporting to a translating mRNP.
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Deans, Robert. "Engineering Biology—Accelerating Translation". Genetic Engineering & Biotechnology News 41, nr 1 (1.01.2021): 44–45. http://dx.doi.org/10.1089/gen.41.01.10.
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Aryanpur, Peyman P., David M. Renner, Emily Rodela, Telsa M. Mittelmeier, Aaron Byrd i Timothy A. Bolger. "The DEAD-box RNA helicase Ded1 has a role in the translational response to TORC1 inhibition". Molecular Biology of the Cell 30, nr 17 (sierpień 2019): 2171–84. http://dx.doi.org/10.1091/mbc.e18-11-0702.
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Ded1 is a DEAD-box RNA helicase with essential roles in translation initiation. It binds to the eukaryotic initiation factor 4F (eIF4F) complex and promotes 48S preinitiation complex assembly and start-site scanning of 5′ untranslated regions of mRNAs. Most prior studies of Ded1 cellular function were conducted in steady-state conditions during nutrient-rich growth. In this work, however, we examine its role in the translational response during target of rapamycin (TOR)C1 inhibition and identify a novel function of Ded1 as a translation repressor. We show that C-terminal mutants of DED1 are defective in down-regulating translation following TORC1 inhibition using rapamycin. Furthermore, following TORC1 inhibition, eIF4G1 normally dissociates from translation complexes and is degraded, and this process is attenuated in mutant cells. Mapping of the functional requirements for Ded1 in this translational response indicates that Ded1 enzymatic activity and interaction with eIF4G1 are required, while homo-oligomerization may be dispensable. Our results are consistent with a model wherein Ded1 stalls translation and specifically removes eIF4G1 from translation preinitiation complexes, thus removing eIF4G1 from the translating mRNA pool and leading to the codegradation of both proteins. Shared features among DED1 orthologues suggest that this role is conserved and may be implicated in pathologies such as oncogenesis.
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Gough, N. R. "Translation Required for Translational Repression". Science Signaling 2, nr 80 (21.07.2009): ec249-ec249. http://dx.doi.org/10.1126/scisignal.280ec249.
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Bania*, Allif Syahputra, Nuraini Nuraini, Nursamsu Nursamsu i Muhammad Yakob. "The Quality of Taxonomy Translation in English Indonesian Latin by Biological Education Students". Jurnal Pendidikan Sains Indonesia 9, nr 4 (15.10.2021): 694–710. http://dx.doi.org/10.24815/jpsi.v9i4.21562.
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Translation of literacy in english, Indonesian and latin has a strategic position in the biological sciences that must be studied with good quality for students so that the development of science. The purpose of this study is to examine the quality of taxonomy translation in English, Indonesian and Latin with regard to biology education. This research is a quantitative-descriptive research. The test method is used to collect data on the ability to translate in biology education learning by using the google form media provided through the biology student WhatsApp group due to the Covid-19 pandemic in the form of 10 questions with a blend of English, Latin and Indonesian about taxonomy. There are 13 respondents who are ready to answer the test. The test is given for 1 credit which is about 45 minutes as the deadline. The data analysis technique in this study is descriptive quantitative which uses three lines of research activities, namely data reduction, data display, and conclusion drawing/verification.The results obtained by respondents find it easier to translate test questions in short sentences. The quality of taxonomy translations related to English, Indonesian and Latin have good quality because from the first session, namely translation into the target language English, 4 of the total questions were obtained with the percentage of success by students in translating well above 50%. Likewise for the results of the translation with the target language Indonesian, the respondents managed to answer all questions well with a percentage above 50%. Here it can be seen that, translating into the target language Indonesian is still easier for respondents to produce because all questions are of high value than translating into the target language English.
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Zhang, Cuiling. "Neuroscience and Translation". International Journal of Translation and Interpreting Research 15, nr 2 (31.07.2023): 180–83. http://dx.doi.org/10.12807/ti.115202.2023.r02.
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In the past decades, researchers have established various theories and approaches to explore the nature of translation, this “most complex type of event yet produced in the evolution of the cosmos” (Richard, 1953:250). Especially since the inception of Translation Studies as an academic discipline in the 1970s, translation scholars have drawn extensively on tools, concepts, and theories from other disciplines, such as sociology, anthropology, psychology, and biology in their efforts to explore the many facets of translation and interpreting. Now, neuroscience came to the fore. As the study of the nervous system, the task of neuroscience is to understand brain processes— how we perceive, act, learn, and remember – and explain behavior in terms of brain activities (Kandel et al., 2012, pp. 3-5). For decades, neuroscientists have explored human language and have produced remarkable studies on language development and learning. Yet the findings on how the brain handles language processing are still primarily based on monolinguals. The mental process of multilingual people and many other aspects of the transfer between different languages remain largely unsettled. This inspired Maria Tymoczko to explore the neurological mechanisms involved in translating, a field that she dubs as one of the “known unknowns” in translation studies (Tymoczko, 2012) and believes will fundamentally influence the way translation is thought about and ultimately illuminate many aspects of translation, including the “black box” of the individual translator.
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Weiner, George. "Cancer biology: Lost in translation?" Cancer Biology & Therapy 3, nr 7 (lipiec 2004): 688–91. http://dx.doi.org/10.4161/cbt.3.7.959.
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Gold, Larry. "Translation, genetics and cell biology". Trends in Genetics 3 (styczeń 1987): 236–37. http://dx.doi.org/10.1016/0168-9525(87)90251-4.
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Kiberstis, P. A. "MOLECULAR BIOLOGY: Translation by Entrapment". Science 299, nr 5606 (24.01.2003): 475a—475. http://dx.doi.org/10.1126/science.299.5606.475a.
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Mezl, Vasek A., Jane Clark i Pascale M. Garber. "Heating RNA before cell-free translation gives no selective increases among the translation products of RNA from rat heart and mammary gland, rabbit reticulocyte membranes, or trout liver". Biochemistry and Cell Biology 64, nr 6 (1.06.1986): 504–8. http://dx.doi.org/10.1139/o86-070.
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A recent study has reported that the heating of a population of guanidinium-extracted mRNAs prior to translation causes a selective increase in the translation of certain mRNAs. To determine if this phenomenon is a general property of mRNAs, we carried out a comparison of the translation products obtained when phenol-extracted rat heart and mammary gland RNAs, rabbit reticulocyte membrane RNAs, and trout liver RNAs were translated in the reticulocyte translation system, with and without a prior heat treatment. Our results show that no selective increase in the translation of mRNAs was observed for any of these samples. Among the 14 RNA preparations examined, one total mammary RNA preparation did display a twofold increase in the translation of all mRNAs after heat treatment. It is shown that the heat enhancement of translational activity observed for this sample was due to the reversible formation of intermolecular aggregates with a contaminant that can be removed by chromatography on oligo(dT)-cellulose. Since heat treatment did not selectively enhance the activity of any mRNA in these samples, our results show that the current practice of translating phenol-extracted RNAs without a prior heat treatment should be satisfactory for the translation of most mRNA populations.
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Sivan, Gilad, Nancy Kedersha i Orna Elroy-Stein. "Ribosomal Slowdown Mediates Translational Arrest during Cellular Division". Molecular and Cellular Biology 27, nr 19 (30.07.2007): 6639–46. http://dx.doi.org/10.1128/mcb.00798-07.
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ABSTRACT Global mRNA translation is transiently inhibited during cellular division. We demonstrate that mitotic cells contain heavy polysomes, but these are significantly less translationally active than polysomes in cycling cells. Several observations indicate that mitotic translational attenuation occurs during the elongation stage: (i) in cycling nonsynchronized cultures, only mitotic cells fail to assemble stress granules when treated with agents that inhibit translational initiation; (ii) mitotic cells contain fewer free 80S complexes, which are less sensitive to high salt disassembly; (iii) mitotic polysomes are more resistant to enforced disassembly using puromycin; and (iv) ribosome transit time increases during mitosis. Elongation slowdown guarantees that polysomes are retained even if initiation is inhibited at the same time. Stalling translating ribosomes during mitosis may protect mRNAs and allow rapid resumption of translation immediately upon entry into the G1 phase.
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Ji, Yingbiao, i Alexei V. Tulin. "Poly(ADP-Ribosyl)ation of hnRNP A1 Protein Controls Translational Repression in Drosophila". Molecular and Cellular Biology 36, nr 19 (11.07.2016): 2476–86. http://dx.doi.org/10.1128/mcb.00207-16.
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Poly(ADP-ribosyl)ation of heterogeneous nuclear ribonucleoproteins (hnRNPs) regulates the posttranscriptional fate of RNA during development.DrosophilahnRNP A1, Hrp38, is required for germ line stem cell maintenance and oocyte localization. The mRNA targets regulated by Hrp38 are mostly unknown. We identified 428 Hrp38-associated gene transcripts in the fly ovary, including mRNA of the translational repressor Nanos. We found that Hrp38 binds to the 3′ untranslated region (UTR) of Nanos mRNA, which contains a translation control element. We have demonstrated that translation of the luciferase reporter bearing the Nanos 3′ UTR is enhanced by dsRNA-mediated Hrp38 knockdown as well as by mutating potential Hrp38-binding sites. Our data show that poly(ADP-ribosyl)ation inhibits Hrp38 binding to the Nanos 3′ UTR, increasing the translationin vivoandin vitro.hrp38andPargnull mutants showed an increased ectopic Nanos translation early in the embryo. We conclude that Hrp38 represses Nanos translation, whereas its poly(ADP-ribosyl)ation relieves the repression effect, allowing restricted Nanos expression in the posterior germ plasm during oogenesis and early embryogenesis.
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Marina, Digregorio, Lombard Arnaud, Lumapat Paul Noel, Scholtes Felix, Rogister Bernard i Coppieters Natacha. "Relevance of Translation Initiation in Diffuse Glioma Biology and its Therapeutic Potential". Cells 8, nr 12 (29.11.2019): 1542. http://dx.doi.org/10.3390/cells8121542.
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Cancer cells are continually exposed to environmental stressors forcing them to adapt their protein production to survive. The translational machinery can be recruited by malignant cells to synthesize proteins required to promote their survival, even in times of high physiological and pathological stress. This phenomenon has been described in several cancers including in gliomas. Abnormal regulation of translation has encouraged the development of new therapeutics targeting the protein synthesis pathway. This approach could be meaningful for glioma given the fact that the median survival following diagnosis of the highest grade of glioma remains short despite current therapy. The identification of new targets for the development of novel therapeutics is therefore needed in order to improve this devastating overall survival rate. This review discusses current literature on translation in gliomas with a focus on the initiation step covering both the cap-dependent and cap-independent modes of initiation. The different translation initiation protagonists will be described in normal conditions and then in gliomas. In addition, their gene expression in gliomas will systematically be examined using two freely available datasets. Finally, we will discuss different pathways regulating translation initiation and current drugs targeting the translational machinery and their potential for the treatment of gliomas.
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Zhao, Jing, Bo Qin, Rainer Nikolay, Christian M. T. Spahn i Gong Zhang. "Translatomics: The Global View of Translation". International Journal of Molecular Sciences 20, nr 1 (8.01.2019): 212. http://dx.doi.org/10.3390/ijms20010212.
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In all kingdoms of life, proteins are synthesized by ribosomes in a process referred to as translation. The amplitude of translational regulation exceeds the sum of transcription, mRNA degradation and protein degradation. Therefore, it is essential to investigate translation in a global scale. Like the other “omics”-methods, translatomics investigates the totality of the components in the translation process, including but not limited to translating mRNAs, ribosomes, tRNAs, regulatory RNAs and nascent polypeptide chains. Technical advances in recent years have brought breakthroughs in the investigation of these components at global scale, both for their composition and dynamics. These methods have been applied in a rapidly increasing number of studies to reveal multifaceted aspects of translation control. The process of translation is not restricted to the conversion of mRNA coding sequences into polypeptide chains, it also controls the composition of the proteome in a delicate and responsive way. Therefore, translatomics has extended its unique and innovative power to many fields including proteomics, cancer research, bacterial stress response, biological rhythmicity and plant biology. Rational design in translation can enhance recombinant protein production for thousands of times. This brief review summarizes the main state-of-the-art methods of translatomics, highlights recent discoveries made in this field and introduces applications of translatomics on basic biological and biomedical research.
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Iizuka, N., L. Najita, A. Franzusoff i P. Sarnow. "Cap-dependent and cap-independent translation by internal initiation of mRNAs in cell extracts prepared from Saccharomyces cerevisiae". Molecular and Cellular Biology 14, nr 11 (listopad 1994): 7322–30. http://dx.doi.org/10.1128/mcb.14.11.7322-7330.1994.
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Translation extracts were prepared from various strains of Saccharomyces cerevisiae. The translation of mRNA molecules in these extracts were cooperatively enhanced by the presence of 5'-terminal cap structures and 3'-terminal poly(A) sequences. These cooperative effects could not be observed in other translation systems such as those prepared from rabbit reticulocytes, wheat germ, and human HeLa cells. Because the yeast translation system mimicked the effects of the cap structure and poly(A) tail on translational efficiency seen in vivo, this system was used to study cap-dependent and cap-independent translation of viral and cellular mRNA molecules. Both the 5' noncoding regions of hepatitis C virus and those of coxsackievirus B1 conferred cap-independent translation to a reporter coding region during translation in the yeast extracts; thus, the yeast translational apparatus is capable of initiating cap-independent translation. Although the translation of most yeast mRNAs was cap dependent, the unusually long 5' noncoding regions of mRNAs encoding cellular transcription factors TFIID and HAP4 were shown to mediate cap-independent translation in these extracts. Furthermore, both TFIID and HAP4 5' noncoding regions mediated translation of a second cistron when placed into the intercistronic spacer region of a dicistronic mRNA, indicating that these leader sequences can initiate translation by an internal ribosome binding mechanism in this in vitro translation system. This finding raises the possibility that an internal translation initiation mechanism exists in yeast cells for regulated translation of endogenous mRNAs.
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Nakazawa, Kaori, Yuichi Shichino, Shintaro Iwasaki i Nobuyuki Shiina. "Implications of RNG140 (caprin2)-mediated translational regulation in eye lens differentiation". Journal of Biological Chemistry 295, nr 44 (23.08.2020): 15029–44. http://dx.doi.org/10.1074/jbc.ra120.012715.
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Regulation of gene expression at the translational level is key to determining cell fate and function. An RNA-binding protein, RNG140 (caprin2), plays a role in eye lens differentiation and has been reported to function in translational regulation. However, the mechanism and its role in eyes has remained unclear. Here, we show that RNG140 binds to the translation initiation factor eukaryotic initiation factor 3 (eIF3) and suppresses translation through mechanisms involving suppression of eIF3-dependent translation initiation. Comprehensive ribosome profiling revealed that overexpression of RNG140 in cultured Chinese hamster ovary cells reduces translation of long mRNAs, including those associated with cell proliferation. RNG140-mediated translational regulation also operates in the mouse eye, where RNG140 knockout increased the translation of long mRNAs. mRNAs involved in lens differentiation, such as crystallin mRNAs, are short and can escape translational inhibition by RNG140 and be translated in differentiating lenses. Thus, this study provides insights into the mechanistic basis of lens cell transition from proliferation to differentiation via RNG140-mediated translational regulation.
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Matsuo, Yoshitaka, i Toshifumi Inada. "Co-Translational Quality Control Induced by Translational Arrest". Biomolecules 13, nr 2 (7.02.2023): 317. http://dx.doi.org/10.3390/biom13020317.
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Genetic mutations, mRNA processing errors, and lack of availability of charged tRNAs sometimes slow down or completely stall translating ribosomes. Since an incomplete nascent chain derived from stalled ribosomes may function anomalously, such as by forming toxic aggregates, surveillance systems monitor every step of translation and dispose of such products to prevent their accumulation. Over the past decade, yeast models with powerful genetics and biochemical techniques have contributed to uncovering the mechanism of the co-translational quality control system, which eliminates the harmful products generated from aberrant translation. We here summarize the current knowledge of the molecular mechanism of the co-translational quality control systems in yeast, which eliminate the incomplete nascent chain, improper mRNAs, and faulty ribosomes to maintain cellular protein homeostasis.
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Linder, Patrick. "Molecular biology of translation in yeast". Antonie van Leeuwenhoek 62, nr 1-2 (sierpień 1992): 47–62. http://dx.doi.org/10.1007/bf00584462.
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Tharp, Jeffery M., Natalie Krahn, Umesh Varshney i Dieter Söll. "Hijacking Translation Initiation for Synthetic Biology". ChemBioChem 21, nr 10 (2.03.2020): 1387–96. http://dx.doi.org/10.1002/cbic.202000017.
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Kawai, Tomoko, Ashish Lal, Xiaoling Yang, Stefanie Galban, Krystyna Mazan-Mamczarz i Myriam Gorospe. "Translational Control of Cytochrome c by RNA-Binding Proteins TIA-1 and HuR". Molecular and Cellular Biology 26, nr 8 (15.04.2006): 3295–307. http://dx.doi.org/10.1128/mcb.26.8.3295-3307.2006.
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ABSTRACT Stresses affecting the endoplasmic reticulum (ER) globally modulate gene expression patterns by altering posttranscriptional processes such as translation. Here, we use tunicamycin (Tn) to investigate ER stress-triggered changes in the translation of cytochrome c, a pivotal regulator of apoptosis. We identified two RNA-binding proteins that associate with its ∼900-bp-long, adenine- and uridine-rich 3′ untranslated region (UTR): HuR, which displayed affinity for several regions of the cytochrome c 3′UTR, and T-cell-restricted intracellular antigen 1 (TIA-1), which preferentially bound the segment proximal to the coding region. HuR did not appear to influence the cytochrome c mRNA levels but instead promoted cytochrome c translation, as HuR silencing greatly diminished the levels of nascent cytochrome c protein. By contrast, TIA-1 functioned as a translational repressor of cytochrome c, with interventions to silence TIA-1 dramatically increasing cytochrome c translation. Following treatment with Tn, HuR binding to cytochrome c mRNA decreased, and both the presence of cytochrome c mRNA within actively translating polysomes and the rate of cytochrome c translation declined. Taken together, our data suggest that the translation rate of cytochrome c is determined by the opposing influences of HuR and TIA-1 upon the cytochrome c mRNA. Under unstressed conditions, cytochrome c mRNA is actively translated, but in response to ER stress agents, both HuR and TIA-1 contribute to lowering its biosynthesis rate. We propose that HuR and TIA-1 function coordinately to maintain precise levels of cytochrome c production under unstimulated conditions and to modify cytochrome c translation when damaged cells are faced with molecular decisions to follow a prosurvival or a prodeath path.
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HAKAMI, H., i D. BOLLEGALA. "A classification approach for detecting cross-lingual biomedical term translations". Natural Language Engineering 23, nr 1 (14.12.2015): 31–51. http://dx.doi.org/10.1017/s1351324915000431.
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AbstractFinding translations for technical terms is an important problem in machine translation. In particular, in highly specialized domains such as biology or medicine, it is difficult to find bilingual experts to annotate sufficient cross-lingual texts in order to train machine translation systems. Moreover, new terms are constantly being generated in the biomedical community, which makes it difficult to keep the translation dictionaries up to date for all language pairs of interest. Given a biomedical term in one language (source language), we propose a method for detecting its translations in a different language (target language). Specifically, we train a binary classifier to determine whether two biomedical terms written in two languages are translations. Training such a classifier is often complicated due to the lack of common features between the source and target languages. We propose several feature space concatenation methods to successfully overcome this problem. Moreover, we study the effectiveness of contextual and character n-gram features for detecting term translations. Experiments conducted using a standard dataset for biomedical term translation show that the proposed method outperforms several competitive baseline methods in terms of mean average precision and top-k translation accuracy.
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Mayfield, S. P., A. Cohen, A. Danon i C. B. Yohn. "Translation of the psbA mRNA of Chlamydomonas reinhardtii requires a structured RNA element contained within the 5' untranslated region." Journal of Cell Biology 127, nr 6 (15.12.1994): 1537–45. http://dx.doi.org/10.1083/jcb.127.6.1537.
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Translational regulation is a key modulator of gene expression in chloroplasts of higher plants and algae. Genetic analysis has shown that translation of chloroplast mRNAs requires nuclear-encoded factors that interact with chloroplastic mRNAs in a message-specific manner. Using site-specific mutations of the chloroplastic psbA mRNA, we show that RNA elements contained within the 5' untranslated region of the mRNA are required for translation. One of these elements is a Shine-Dalgarno consensus sequence, which is necessary for ribosome association and psbA translation. A second element required for high levels of psbA translation is located adjacent to and upstream of the Shine-Dalgarno sequence, and maps to the location on the RNA previously identified as the site of message-specific protein binding. This second element appears to act as a translational attenuator that must be overcome to activate translation. Mutations that affect the secondary structure of these RNA elements greatly reduce the level of psbA translation, suggesting that secondary structure of these RNA elements plays a role in psbA translation. These data suggest a mechanism for translational activation of the chloroplast psbA mRNA in which an RNA element containing the ribosome-binding site is bound by message-specific RNA binding proteins allowing for increased ribosome association and translation initiation. These elements may be involved in the light-regulated translation of the psbA mRNA.
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Gillian-Daniel, Donald L., Nicola K. Gray, Jonas Åström, Aaron Barkoff i Marvin Wickens. "Modifications of the 5′ Cap of mRNAs duringXenopus Oocyte Maturation: Independence from Changes in Poly(A) Length and Impact on Translation". Molecular and Cellular Biology 18, nr 10 (1.10.1998): 6152–63. http://dx.doi.org/10.1128/mcb.18.10.6152.
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ABSTRACT The translation of specific maternal mRNAs is regulated during early development. For some mRNAs, an increase in translational activity is correlated with cytoplasmic extension of their poly(A) tails; for others, translational inactivation is correlated with removal of their poly(A) tails. Recent results in several systems suggest that events at the 3′ end of the mRNA can affect the state of the 5′ cap structure, m7G(5′)ppp(5′)G. We focus here on the potential role of cap modifications on translation during early development and on the question of whether any such modifications are dependent on cytoplasmic poly(A) addition or removal. To do so, we injected synthetic RNAs into Xenopus oocytes and examined their cap structures and translational activities during meiotic maturation. We draw four main conclusions. First, the activity of a cytoplasmic guanine-7-methyltransferase increases during oocyte maturation and stimulates translation of an injected mRNA bearing a nonmethylated GpppG cap. The importance of the cap for translation in oocytes is corroborated by the sensitivity of protein synthesis to cap analogs and by the inefficient translation of mRNAs bearing nonphysiologically capped 5′ termini. Second, deadenylation during oocyte maturation does not cause decapping, in contrast to deadenylation-triggered decapping in Saccharomyces cerevisiae. Third, the poly(A) tail and the N-7 methyl group of the cap stimulate translation synergistically during oocyte maturation. Fourth, cap ribose methylation of certain mRNAs is very inefficient and is not required for their translational recruitment by poly(A). These results demonstrate that polyadenylation can cause translational recruitment independent of ribose methylation. We propose that polyadenylation enhances translation through at least two mechanisms that are distinguished by their dependence on ribose modification.
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Waite, J. Herbert. "Translational bioadhesion research: embracing biology without tokenism". Philosophical Transactions of the Royal Society B: Biological Sciences 374, nr 1784 (9.09.2019): 20190207. http://dx.doi.org/10.1098/rstb.2019.0207.
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Bioadhesion has attracted a sizable research community of scientists and engineers that is striving increasingly for translational outcomes in anti-fouling and bioinspired adhesion initiatives. As bioadhesion is highly context-dependent, attempts to trivialize or gloss over the fundamental physical, chemical and biological sciences involved will compromise the relevance and durability of translation. This article is part of the theme issue ‘Transdisciplinary approaches to the study of adhesion and adhesives in biological systems'.
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Anand, Padmanabhan, i Philip A. Gruppuso. "The Regulation of Hepatic Protein Synthesis during Fasting in the Rat". Journal of Biological Chemistry 280, nr 16 (16.02.2005): 16427–36. http://dx.doi.org/10.1074/jbc.m410576200.
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We have studied translational control in the model of 48 h of fasting in the rat. Our initial observations showed a paradoxical increase in ribosomal protein S6 (rpS6) phosphorylation and a decrease in eukaryotic initiation factor 2α (eIF2α) phosphorylation. These effects, which would favor an increase in protein synthesis, could be attributed to increased circulating concentrations of branched-chain amino acids in fasting. To determine what mechanisms might account for decreased hepatic translation in fasting, we examined the cap binding complex. eIF4E-bound 4E-BP1 did not increase. However, eIF4E-bound eIF4G and total cellular eIF4G were profoundly decreased in fasted liver. eIF4G mRNA levels were not lower after fasting. Based on the hypothesis that decreased eIF4G translation might account for the reduced eIF4G content, we fractionated ribosomes by sucrose density centrifugation. Immunoblotting for rpS6 showed modest polysomal disaggregation upon fasting. PCR analysis of polysome profiles revealed that a spectrum of mRNAs undergo different translational regulation in the fasted state. In particular, eIF4G was minimally affected by fasting. This indicated that reduced eIF4G abundance in fasting may be a function of its stability, whereas its recovery upon refeeding is necessarily independent of its own involvement in the cap binding complex. Western immunoblotting of polysome fractions showed that phosphorylated rpS6 was disproportionately present in translating polysomes in fed and fasted animals, consistent with a role in translational control. However, the translation of rpS8, an mRNA with a 5′-oligopyrimidine tract, did not coincide with rpS6 phosphorylation, thus dissociating rpS6 phosphorylation from the translational control of this subset of mRNAs.
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Tollerson, Rodney, i Michael Ibba. "Translational regulation of environmental adaptation in bacteria". Journal of Biological Chemistry 295, nr 30 (9.06.2020): 10434–45. http://dx.doi.org/10.1074/jbc.rev120.012742.
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Bacteria must rapidly respond to both intracellular and environmental changes to survive. One critical mechanism to rapidly detect and adapt to changes in environmental conditions is control of gene expression at the level of protein synthesis. At each of the three major steps of translation—initiation, elongation, and termination—cells use stimuli to tune translation rate and cellular protein concentrations. For example, changes in nutrient concentrations in the cell can lead to translational responses involving mechanisms such as dynamic folding of riboswitches during translation initiation or the synthesis of alarmones, which drastically alter cell physiology. Moreover, the cell can fine-tune the levels of specific protein products using programmed ribosome pausing or inducing frameshifting. Recent studies have improved understanding and revealed greater complexity regarding long-standing paradigms describing key regulatory steps of translation such as start-site selection and the coupling of transcription and translation. In this review, we describe how bacteria regulate their gene expression at the three translational steps and discuss how translation is used to detect and respond to changes in the cellular environment. Finally, we appraise the costs and benefits of regulation at the translational level in bacteria.
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Falcone, D., i D. W. Andrews. "Both the 5' untranslated region and the sequences surrounding the start site contribute to efficient initiation of translation in vitro". Molecular and Cellular Biology 11, nr 5 (maj 1991): 2656–64. http://dx.doi.org/10.1128/mcb.11.5.2656-2664.1991.
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The role of RNA sequences in the 5' leader region between the cap site and initiating AUG in mediating translation was examined in vitro. Hybrid mRNAs were synthesized in which the cognate leader sequence was replaced with either optimized or compromised leader sequences, and translational efficiency was measured for six different coding regions. Translation was most efficient with a leader containing the 5' untranslated region from Xenopus beta-globin and an optimized initiation sequence. Compared with the cognate leaders, this hybrid was observed to increase translation of the various coding regions as much as 300-fold. The translational efficiencies of the different coding regions also varied substantially. In contrast to earlier suggestions that increased leader efficiency results from higher affinity of the leader for a limiting factor, our experiments suggest that increased translation from the beta-globin hybrid leader sequence results from more rapid initiation of translation.
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Kim, Jong Heon, Ki Young Paek, Sang Hoon Ha, Sungchan Cho, Kobong Choi, Chon Saeng Kim, Sung Ho Ryu i Sung Key Jang. "A Cellular RNA-Binding Protein Enhances Internal Ribosomal Entry Site-Dependent Translation through an Interaction Downstream of the Hepatitis C Virus Polyprotein Initiation Codon". Molecular and Cellular Biology 24, nr 18 (15.09.2004): 7878–90. http://dx.doi.org/10.1128/mcb.24.18.7878-7890.2004.
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ABSTRACT Translational initiation of hepatitis C virus (HCV) mRNA occurs by internal entry of ribosomes into an internal ribosomal entry site (IRES) at the 5′ nontranslated region. A region encoding the N-terminal part of the HCV polyprotein has been shown to augment the translation of HCV mRNA. Here we show that a cellular protein, NS1-associated protein 1 (NSAP1), augments HCV mRNA translation through a specific interaction with an adenosine-rich protein-coding region within the HCV mRNA. The overexpression of NSAP1 specifically enhanced HCV IRES-dependent translation, and knockdown of NSAP1 by use of a small interfering RNA specifically inhibited the translation of HCV mRNA. An HCV replicon RNA capable of mimicking the HCV proliferation process in host cells was further used to confirm that NSAP1 enhances the translation of HCV mRNA. These results suggest the existence of a novel mechanism of translational enhancement that acts through the interaction of an RNA-binding protein with a protein coding sequence.
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Mazumder, Barsanjit, Vasudevan Seshadri, Hiroaki Imataka, Nahum Sonenberg i Paul L. Fox. "Translational Silencing of Ceruloplasmin Requires the Essential Elements of mRNA Circularization: Poly(A) Tail, Poly(A)-Binding Protein, and Eukaryotic Translation Initiation Factor 4G". Molecular and Cellular Biology 21, nr 19 (1.10.2001): 6440–49. http://dx.doi.org/10.1128/mcb.21.19.6440-6449.2001.
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ABSTRACT Ceruloplasmin (Cp) is a glycoprotein secreted by the liver and monocytic cells and probably plays roles in inflammation and iron metabolism. We showed previously that gamma interferon (IFN-γ) induced Cp synthesis by human U937 monocytic cells but that the synthesis was subsequently halted by a transcript-specific translational silencing mechanism involving the binding of a cytosolic factor(s) to the Cp mRNA 3′ untranslated region (UTR). To investigate how protein interactions at the Cp 3′-UTR inhibit translation initiation at the distant 5′ end, we considered the “closed-loop” model of mRNA translation. In this model, the transcript termini are brought together by interactions of poly(A)-binding protein (PABP) with both the poly(A) tail and initiation factor eIF4G. The effect of these elements on Cp translational control was tested using chimeric reporter transcripts in rabbit reticulocyte lysates. The requirement for poly(A) was shown since the cytosolic inhibitor from IFN-γ-treated cells minimally inhibited the translation of a luciferase reporter upstream of the Cp 3′-UTR but almost completely blocked the translation of a transcript containing a poly(A) tail. Likewise, a requirement for poly(A) was shown for silencing of endogenous Cp mRNA. We considered the possibility that the cytosolic inhibitor blocked the interaction of PABP with the poly(A) tail or with eIF4G. We found that neither of these interactions were inhibited, as shown by immunoprecipitation of PABP followed by quantitation of the poly(A) tail by reverse transcription-PCR and of eIF4G by immunoblot analysis. We considered the alternate possibility that these interactions were required for translational silencing. When PABP was depleted from the reticulocyte lysate with anti-human PABP antibody, the cytosolic factor did not inhibit translation of the chimeric reporter, thus showing the requirement for PABP. Similarly, in lysates treated with anti-human eIF4G antibody, the cytosolic extract did not inhibit the translation of the chimeric reporter, thereby showing a requirement for eIF4G. These data show that translational silencing of Cp requires interactions of three essential elements of mRNA circularization, poly(A), PABP, and eIF4G. We suggest that Cp mRNA circularization brings the cytosolic Cp 3′-UTR-binding factor into the proximity of the translation initiation site, where it silences translation by an undetermined mechanism. These results suggest that in addition to its important function in increasing the efficiency of translation, transcript circularization may serve as an essential structural determinant for transcript-specific translational control.
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Patursky-Polischuk, Ilona, Miri Stolovich-Rain, Mirit Hausner-Hanochi, Judith Kasir, Nadine Cybulski, Joseph Avruch, Markus A. Rüegg, Michael N. Hall i Oded Meyuhas. "The TSC-mTOR Pathway Mediates Translational Activation of TOP mRNAs by Insulin Largely in a Raptor- or Rictor-Independent Manner". Molecular and Cellular Biology 29, nr 3 (1.12.2008): 640–49. http://dx.doi.org/10.1128/mcb.00980-08.
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ABSTRACT The stimulatory effect of insulin on protein synthesis is due to its ability to activate various translation factors. We now show that insulin can increase protein synthesis capacity also by translational activation of TOP mRNAs encoding various components of the translation machinery. This translational activation involves the tuberous sclerosis complex (TSC), as the knockout of TSC1 or TSC2 rescues TOP mRNAs from translational repression in mitotically arrested cells. Similar results were obtained upon overexpression of Rheb, an immediate TSC1-TSC2 target. The role of mTOR, a downstream effector of Rheb, in translational control of TOP mRNAs has been extensively studied, albeit with conflicting results. Even though rapamycin fully blocks mTOR complex 1 (mTORC1) kinase activity, the response of TOP mRNAs to this drug varies from complete resistance to high sensitivity. Here we show that mTOR knockdown blunts the translation efficiency of TOP mRNAs in insulin-treated cells, thus unequivocally establishing a role for mTOR in this mode of regulation. However, knockout of the raptor or rictor gene has only a slight effect on the translation efficiency of these mRNAs, implying that mTOR exerts its effect on TOP mRNAs through a novel pathway with a minor, if any, contribution of the canonical mTOR complexes mTORC1 and mTORC2. This conclusion is further supported by the observation that raptor knockout renders the translation of TOP mRNAs rapamycin hypersensitive.
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Lykke-Andersen, Jens, i Eric J. Bennett. "Protecting the proteome: Eukaryotic cotranslational quality control pathways". Journal of Cell Biology 204, nr 4 (17.02.2014): 467–76. http://dx.doi.org/10.1083/jcb.201311103.
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The correct decoding of messenger RNAs (mRNAs) into proteins is an essential cellular task. The translational process is monitored by several quality control (QC) mechanisms that recognize defective translation complexes in which ribosomes are stalled on substrate mRNAs. Stalled translation complexes occur when defects in the mRNA template, the translation machinery, or the nascent polypeptide arrest the ribosome during translation elongation or termination. These QC events promote the disassembly of the stalled translation complex and the recycling and/or degradation of the individual mRNA, ribosomal, and/or nascent polypeptide components, thereby clearing the cell of improper translation products and defective components of the translation machinery.
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Reynolds, K., A. M. Zimmer i A. Zimmer. "Regulation of RAR beta 2 mRNA expression: evidence for an inhibitory peptide encoded in the 5'-untranslated region." Journal of Cell Biology 134, nr 4 (15.08.1996): 827–35. http://dx.doi.org/10.1083/jcb.134.4.827.
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Regulation of mRNA translation and stability plays an important role in the control of gene expression during embryonic development. We have recently shown that the tissue-specific expression of the RAR beta 2 gene in mouse embryos is regulated at the translational level by short upstream open reading frames (uORFs) In the 5'-untranslated region (Zimmer, A., A.M. Zimmer, and K. Reynolds. 1994. J. Cell Biol. 127:1111-1119). To gain insight into the molecular mechanism, we have performed a systematic mutational analysis of the uORFs. Two series of constructs were tested: in one series, each uORF was individually inactivated by introducing a point mutation in its start codon; in the second series, all but one ORF were inactivated. Our results indicate that individual uORFs may have different functions. uORF4 seems to inhibit translation of the major ORF in heart and brain, while uORFs 2 and 5 appear to be important for efficient translation in all tissues. To determine whether the polypeptide encoded by uORF4 or the act of translating it, is the significant event, we introduced point mutations to create silent mutations or amino acid substitutions in uORF4. Our results indicate that the uORF4 amino acid coding sequence is important for the inhibitory effect on translation of the downstream major ORF.
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Roden, Christine A., i Amy S. Gladfelter. "Design considerations for analyzing protein translation regulation by condensates". RNA 28, nr 1 (20.10.2021): 88–96. http://dx.doi.org/10.1261/rna.079002.121.
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One proposed role for biomolecular condensates that contain RNA is translation regulation. In several specific contexts, translation has been shown to be modulated by the presence of a phase-separating protein and under conditions which promote phase separation, and likely many more await discovery. A powerful tool for determining the rules for condensate-dependent translation is the use of engineered RNA sequences, which can serve as reporters for translation efficiency. This Perspective will discuss design features to consider in engineering RNA reporters to determine the role of phase separation in translational regulation. Specifically, we will cover (i) how to engineer RNA sequence to recapitulate native protein/RNA interactions, (ii) the advantages and disadvantages for commonly used reporter RNA sequences, and (iii) important control experiments to distinguish between binding- and condensation-dependent translational repression. The goal of this review is to promote the design and application of faithful translation reporters to demonstrate a physiological role of biomolecular condensates in translation.
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Nishihori, Taiga, i Kenneth Shain. "Insights on Genomic and Molecular Alterations in Multiple Myeloma and Their Incorporation towards Risk-Adapted Treatment Strategy: Concise Clinical Review". International Journal of Genomics 2017 (2017): 1–6. http://dx.doi.org/10.1155/2017/6934183.
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Although recent advances in novel treatment approaches and therapeutics have shifted the treatment landscape of multiple myeloma, it remains an incurable plasma cell malignancy. Growing knowledge of the genome and expressed genomic information characterizing the biologic behavior of multiple myeloma continues to accumulate. However, translation and incorporation of vast molecular understanding of complex tumor biology to deliver personalized and precision treatment to cure multiple myeloma have not been successful to date. Our review focuses on current evidence and understanding of myeloma biology with characterization in the context of genomic and molecular alterations. We also discuss future clinical application of the genomic and molecular knowledge, and more translational research is needed to benefit our myeloma patients.
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Tao, Xianzun, i Guangxia Gao. "Tristetraprolin Recruits Eukaryotic Initiation Factor 4E2 To Repress Translation of AU-Rich Element-Containing mRNAs". Molecular and Cellular Biology 35, nr 22 (14.09.2015): 3921–32. http://dx.doi.org/10.1128/mcb.00845-15.
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Tristetraprolin (TTP) regulates the expression of AU-rich element-containing mRNAs through promoting the degradation and repressing the translation of target mRNA. While the mechanism for promoting target mRNA degradation has been extensively studied, the mechanism underlying translational repression is not well established. Here, we show that TTP recruits eukaryotic initiation factor 4E2 (eIF4E2) to repress target mRNA translation. TTP interacted with eIF4E2 but not with eIF4E. Overexpression of eIF4E2 enhanced TTP-mediated translational repression, and downregulation of endogenous eIF4E2 or overexpression of a truncation mutant of eIF4E2 impaired TTP-mediated translational repression. Overexpression of an eIF4E2 mutant that lost the cap-binding activity also impaired TTP's activity, suggesting that the cap-binding activity of eIF4E2 is important in TTP-mediated translational repression. We further show that TTP promoted eIF4E2 binding to target mRNA. These results imply that TTP recruits eIF4E2 to compete with eIF4E to repress the translation of target mRNA. This notion is supported by the finding that downregulation of endogenous eIF4E2 increased the production of tumor necrosis factor alpha (TNF-α) protein without affecting the mRNA levels in THP-1 cells. Collectively, these results uncover a novel mechanism by which TTP represses target mRNA translation.
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Mead, Emma J., Rosalyn J. Masterton, Tobias von der Haar, Mick F. Tuite i C. Mark Smales. "Control and regulation of mRNA translation". Biochemical Society Transactions 42, nr 1 (23.01.2014): 151–54. http://dx.doi.org/10.1042/bst20130259.
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Translational control is central to the gene expression pathway and was the focus of the 2013 annual Translation UK meeting held at the University of Kent. The meeting brought together scientists at all career stages to present and discuss research in the mRNA translation field, with an emphasis on the presentations on the research of early career scientists. The diverse nature of this field was represented by the broad range of papers presented at the meeting. The complexity of mRNA translation and its control is emphasized by the interdisciplinary research approaches required to address this area with speakers highlighting emerging systems biology techniques and their application to understanding mRNA translation and the network of pathways controlling it.
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Baleva, Maria V., Ivan Chicherin, Uliana Piunova, Viktor Zgoda, Maxim V. Patrushev, Sergey Levitskii i Piotr Kamenski. "Pentatricopeptide Protein PTCD2 Regulates COIII Translation in Mitochondria of the HeLa Cell Line". International Journal of Molecular Sciences 23, nr 22 (17.11.2022): 14241. http://dx.doi.org/10.3390/ijms232214241.
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Protein biosynthesis in mitochondria is tightly coupled with assembly of inner membrane complexes and therefore must be coordinated with cytosolic translation of the mRNAs corresponding to the subunits which are encoded in the nucleus. Molecular mechanisms underlying the regulation of mitochondrial translation remain unclear despite recent advances in structural biology. Until now, only one translational regulator of protein biosynthesis in mammalian mitochondria is known—protein TACO1, which regulates translation of COI mRNA. Here we describe the function of pentatricopeptide-containing protein PTCD2 as a translational regulator of another mitochondrially encoded subunit of cytochrome c oxidase—COIII in the HeLa cell line. Deletion of the PTCD2 gene leads to significant decrease in COIII translation efficiency and impairment in CIV activity. Additionally, we show that PTCD2 protein is partially co-sedimentates with associated mitochondrial ribosome and associates with mitochondrial ribosome proteins in pull-down assays. These data allow concluding that PTCD2 is a specific translational regulator of COIII which attracts the mRNA to the mitochondrial ribosome.
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Pelletier, Jerry, i Nahum Sonenberg. "The involvement of mRNA secondary structure in protein synthesis". Biochemistry and Cell Biology 65, nr 6 (1.06.1987): 576–81. http://dx.doi.org/10.1139/o87-074.
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Translation initiation in eukaryotes is a complex process involving many factors. A key step in this process is the binding of mRNA to the 43S preinitiation complex. This is generally the rate-limiting step in translation initiation and consequently a major determinant of mRNA translational efficiency. The primary and secondary structure of the mRNA 5′ noncoding region have been implicated in modulating translational efficiency. Translational efficiency was shown to be inversely proportional to the degree of secondary structure at the mRNA 5′ noncoding region. Furthermore, it was shown that cap-binding proteins that interact with the 5′ cap structure (m7GpppN) of eukaryotic mRNAs are involved in the "unwinding" of the mRNA secondary structure, in an ATP hydrolysis mediated event, to facilitate ribosome binding. Thus, cap-binding proteins can potentially regulate mRNA translation. Here, we discuss the available data supporting the notion that eukaryotic 5′ mRNA secondary structure plays an important role in translation initiation and the possible regulation of this process.
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Zambrano, Andrea, Flavia Fontanesi, Asun Solans, Rodrigo Leite de Oliveira, Thomas D. Fox, Alexander Tzagoloff i Antoni Barrientos. "Aberrant Translation of CytochromecOxidase Subunit 1 mRNA Species in the Absence of Mss51p in the YeastSaccharomyces cerevisiae". Molecular Biology of the Cell 18, nr 2 (luty 2007): 523–35. http://dx.doi.org/10.1091/mbc.e06-09-0803.
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Expression of yeast mitochondrial genes depends on specific translational activators acting on the 5′-untranslated region of their target mRNAs. Mss51p is a translational factor for cytochrome c oxidase subunit 1 (COX1) mRNA and a key player in down-regulating Cox1p expression when subunits with which it normally interacts are not available. Mss51p probably acts on the 5′-untranslated region of COX1 mRNA to initiate translation and on the coding sequence itself to facilitate elongation. Mss51p binds newly synthesized Cox1p, an interaction that could be necessary for translation. To gain insight into the different roles of Mss51p on Cox1p biogenesis, we have analyzed the properties of a new mitochondrial protein, mp15, which is synthesized in mss51 mutants and in cytochrome oxidase mutants in which Cox1p translation is suppressed. The mp15 polypeptide is not detected in cox14 mutants that express Cox1p normally. We show that mp15 is a truncated translation product of COX1 mRNA whose synthesis requires the COX1 mRNA-specific translational activator Pet309p. These results support a key role for Mss51p in translationally regulating Cox1p synthesis by the status of cytochrome oxidase assembly.
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Des Soye, Benjamin J., Jaymin R. Patel, Farren J. Isaacs i Michael C. Jewett. "Repurposing the translation apparatus for synthetic biology". Current Opinion in Chemical Biology 28 (październik 2015): 83–90. http://dx.doi.org/10.1016/j.cbpa.2015.06.008.
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Lee, Chien-Der, i Benjamin P. Tu. "Metabolic influences on RNA biology and translation". Critical Reviews in Biochemistry and Molecular Biology 52, nr 2 (2.02.2017): 176–84. http://dx.doi.org/10.1080/10409238.2017.1283294.
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Kojima, Kenji K., Takumi Matsumoto i Haruhiko Fujiwara. "Eukaryotic Translational Coupling in UAAUG Stop-Start Codons for the Bicistronic RNA Translation of the Non-Long Terminal Repeat Retrotransposon SART1". Molecular and Cellular Biology 25, nr 17 (1.09.2005): 7675–86. http://dx.doi.org/10.1128/mcb.25.17.7675-7686.2005.
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ABSTRACT Most eukaryotic cellular mRNAs are monocistronic; however, many retroviruses and long terminal repeat (LTR) retrotransposons encode multiple proteins on a single RNA transcript using ribosomal frameshifting. Non-long terminal repeat (non-LTR) retrotransposons are considered the ancestor of LTR retrotransposons and retroviruses, but their translational mechanism of bicistronic RNA remains unknown. We used a baculovirus expression system to produce a large amount of the bicistronic RNA of SART1, a non-LTR retrotransposon of the silkworm, and were able to detect the second open reading frame protein (ORF2) by Western blotting. The ORF2 protein was translated as an independent protein, not as an ORF1-ORF2 fusion protein. We revealed by mutagenesis that the UAAUG overlapping stop-start codon and the downstream RNA secondary structure are necessary for efficient ORF2 translation. Increasing the distance between the ORF1 stop codon and the ORF2 start codon decreased translation efficiency. These results are different from the eukaryotic translation reinitiation mechanism represented by the yeast GCN4 gene, in which the probability of reinitiation increases as the distance between the two ORFs increases. The translational mechanism of SART1 ORF2 is analogous to translational coupling observed in prokaryotes and viruses. Our results indicate that translational coupling is a general mechanism for bicistronic RNA translation.
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An, Sihyeon, Oh Sung Kwon, Jinbae Yu i Sung Key Jang. "A cyclin-dependent kinase, CDK11/p58, represses cap-dependent translation during mitosis". Cellular and Molecular Life Sciences 77, nr 22 (6.02.2020): 4693–708. http://dx.doi.org/10.1007/s00018-019-03436-3.
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Abstract During mitosis, translation of most mRNAs is strongly repressed; none of the several explanatory hypotheses suggested can fully explain the molecular basis of this phenomenon. Here we report that cyclin-dependent CDK11/p58—a serine/threonine kinase abundantly expressed during M phase—represses overall translation by phosphorylating a subunit (eIF3F) of the translation factor eIF3 complex that is essential for translation initiation of most mRNAs. Ectopic expression of CDK11/p58 strongly repressed cap-dependent translation, and knockdown of CDK11/p58 nullified the translational repression during M phase. We identified the phosphorylation sites in eIF3F responsible for M phase-specific translational repression by CDK11/p58. Alanine substitutions of CDK11/p58 target sites in eIF3F nullified its effects on cell cycle-dependent translational regulation. The mechanism of translational regulation by the M phase-specific kinase, CDK11/p58, has deep evolutionary roots considering the conservation of CDK11 and its target sites on eIF3F from C. elegans to humans.
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Wang, Zhong, Peng Fang i Matthew S. Sachs. "The Evolutionarily Conserved Eukaryotic Arginine Attenuator Peptide Regulates the Movement of Ribosomes That Have Translated It". Molecular and Cellular Biology 18, nr 12 (1.12.1998): 7528–36. http://dx.doi.org/10.1128/mcb.18.12.7528.
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ABSTRACT Translation of the upstream open reading frame (uORF) in the 5′ leader segment of the Neurospora crassa arg-2 mRNA causes reduced initiation at a downstream start codon when arginine is plentiful. Previous examination of this translational attenuation mechanism using a primer-extension inhibition (toeprint) assay in a homologous N. crassa cell-free translation system showed that arginine causes ribosomes to stall at the uORF termination codon. This stalling apparently regulates translation by preventing trailing scanning ribosomes from reaching the downstream start codon. Here we provide evidence that neither the distance between the uORF stop codon and the downstream initiation codon nor the nature of the stop codon used to terminate translation of the uORF-encoded arginine attenuator peptide (AAP) is important for regulation. Furthermore, translation of the AAP coding region regulates synthesis of the firefly luciferase polypeptide when it is fused directly at the N terminus of that polypeptide. In this case, the elongating ribosome stalls in response to Arg soon after it translates the AAP coding region. Regulation by this eukaryotic leader peptide thus appears to be exerted through a novel mechanism ofcis-acting translational control.
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Rakwalska, Magdalena, i Sabine Rospert. "The Ribosome-Bound Chaperones RAC and Ssb1/2p Are Required for Accurate Translation in Saccharomyces cerevisiae". Molecular and Cellular Biology 24, nr 20 (15.10.2004): 9186–97. http://dx.doi.org/10.1128/mcb.24.20.9186-9197.2004.
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ABSTRACT The chaperone homologs RAC (ribosome-associated complex) and Ssb1/2p are anchored to ribosomes; Ssb1/2p directly interacts with nascent polypeptides. The absence of RAC or Ssb1/2p results in a similar set of phenotypes, including hypersensitivity against the aminoglycoside paromomycin, which binds to the small ribosomal subunit and compromises the fidelity of translation. In order to understand this phenomenon we measured the frequency of translation termination and misincorporation in vivo and in vitro with a novel reporter system. Translational fidelity was impaired in the absence of functional RAC or Ssb1/2p, and the effect was further enhanced by paromomycin. The mutant strains suffered primarily from a defect in translation termination, while misincorporation was compromised to a lesser extent. Consistently, a low level of soluble translation termination factor Sup35p enhanced growth defects in the mutant strains. Based on the combined data we conclude that RAC and Ssb1/2p are crucial in maintaining translational fidelity beyond their postulated role as chaperones for nascent polypeptides.
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Kao, H. P., J. R. Abney i A. S. Verkman. "Determinants of the translational mobility of a small solute in cell cytoplasm." Journal of Cell Biology 120, nr 1 (1.01.1993): 175–84. http://dx.doi.org/10.1083/jcb.120.1.175.
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The purposes of this study were: (a) to measure the translational mobility of a small solute in cell cytoplasm; (b) to define quantitatively the factors that determine solute translation; and (c) to compare and contrast solute rotation and translation. A small fluorescent probe, 2,7-bis-(2-carboxyethyl)-5-(and 6-)-carboxyfluorescein (BCECF), was introduced into the cytoplasm of Swiss 3T3 fibroblasts. BCECF translation was measured by fluorescence recovery after photo-bleaching; rotation was measured by Fourier transform polarization microscopy. Diffusion coefficients relative to those in water (D/D0) were determined by comparing mobility in cytoplasm with mobility in standard solutions of known viscosity. At isosmotic cell volume, the relative diffusion coefficients for BCECF translation and rotation in cytoplasm were 0.27 +/- 0.01 (SEM, n = 24, 23 degrees C) and 0.78 +/- 0.03 (n = 4), respectively. As cell volume increased from 0.33 to 2 times isosmotic volume, the relative translational diffusion coefficient increased from 0.047 to 0.32, while the relative rotational diffusion coefficient remained constant. The factors determining BCECF translation were evaluated by comparing rotation and translation in cytoplasm, and in artificial solutions containing dextrans (mobile barriers) and agarose gels (immobile barriers). It was concluded that the hindrance of BCECF translation in cytoplasm could be quantitatively attributed to three independent factors: (a) fluid-phase cytoplasmic viscosity is 28% greater than the viscosity of water (factor 1 = 0.78); (b) 19% of BCECF is transiently bound to intracellular components of low mobility (factor 2 = 0.81); and most importantly, (c) translation of unbound BCECF is hindered 2.5-fold by collisions with cell solids comprising 13% of isosmotic cell volume (factor 3 = 0.40). The product of the 3 factors is 0.25 +/- 0.03, in good agreement with the measured D/D0 of 0.27 +/- 0.01. These results provide the first measurement of the translational mobility of a small solute in cell cytoplasm and define quantitatively the factors that slow solute translation.
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Miller, Susan J., Tuangporn Suthiphongchai, Gerard P. Zambetti i Mark E. Ewen. "p53 Binds Selectively to the 5′ Untranslated Region ofcdk4, an RNA Element Necessary and Sufficient for Transforming Growth Factor β- and p53-Mediated Translational Inhibition of cdk4". Molecular and Cellular Biology 20, nr 22 (15.11.2000): 8420–31. http://dx.doi.org/10.1128/mcb.20.22.8420-8431.2000.
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ABSTRACT One consequence of transforming growth factor β (TGF-β) treatment is inhibition of Cdk4 synthesis, and this is dependent on p53. Here, we show that the 5′ untranslated region (UTR) of thecdk4 mRNA is both necessary and sufficient for wild-type p53-dependent TGF-β-regulated translational inhibition of cdk4. Wild-type p53 bound selectively to the 5′ UTR of the cdk4 mRNA and inhibited translation of RNAs that contain this region. RNA binding and translational control are two genetically separable functions of p53, as are specific and nonspecific RNA binding. Moreover, transactivation-defective mutants of p53 retain the ability to regulate cdk4 translation. Our findings suggest that p53 functions as a regulator of translation in response to TGF-β in vivo.
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Wreden, C., A. C. Verrotti, J. A. Schisa, M. E. Lieberfarb i S. Strickland. "Nanos and pumilio establish embryonic polarity in Drosophila by promoting posterior deadenylation of hunchback mRNA". Development 124, nr 15 (1.08.1997): 3015–23. http://dx.doi.org/10.1242/dev.124.15.3015.
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Nanos protein promotes abdominal structures in Drosophila embryos by repressing the translation of maternal hunchback mRNA in the posterior. To study the mechanism of nanos-mediated translational repression, we first examined the mechanism by which maternal hunchback mRNA is translationally activated. In the absence of nanos activity, the poly(A) tail of hunchback mRNA is elongated concomitant with its translation, suggesting that cytoplasmic polyadenylation directs activation. However, in the presence of nanos the length of the hunchback mRNA poly(A) tail is reduced. To determine if nanos activity represses translation by altering the polyadenylation state of hunchback mRNA, we injected various in vitro transcribed RNAs into Drosophila embryos and determined changes in polyadenylation. Nanos activity reduced the polyadenylation status of injected hunchback RNAs by accelerating their deadenylation. Pumilio activity, which is necessary to repress the translation of hunchback, is also needed to alter polyadenylation. An examination of translation indicates a strong correlation between poly(A) shortening and suppression of translation. These data indicate that nanos and pumilio determine posterior morphology by promoting the deadenylation of maternal hunchback mRNA, thereby repressing its translation.
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Browder, Leon W., Jillian Wilkes-Johnston i Sherri D. Fraser. "5'-3' Interactions in regulation of translation in Xenopus early embryos". Biochemistry and Cell Biology 75, nr 6 (1.12.1997): 739–48. http://dx.doi.org/10.1139/o97-066.
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We have investigated the effects of 3' noncoding elements in enhancing translation of messengers having translation-inhibiting 5' untranslated regions (UTRs). The translation of transcripts bearing the 5' UTRs of either human c-myc or a synthetic hairpin structure upstream of a chloramphenicol acetyltransferase (CAT) reporter sequence is greatly attenuated in early embryos of Xenopus laevis. Translation of transcripts bearing the human c-myc-5' UTR was markedly stimulated by the presence of 3' poly(A). Transcripts bearing the 5' hairpin element were insensitive to the presence of poly(A), but they were extremely sensitive to the composition of the 3' UTR. A GC-rich distal sequence repressed translation, whereas a proximal GGAAU sequence promoted translation of these transcripts. Our results support the concept that long-range interactions between the 5' and 3' ends of transcripts are important in regulating translation in Xenopus embryos. Key words: translational regulation, oncogenes, c-myc, Xenopus laevis, development, embryo.