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Luha R, Rana V, Vainstein A, Kumar V. Nonsense-mediated mRNA decay pathway in plants under stress: general gene regulatory mechanism and advances. PLANTA 2024; 259:51. [PMID: 38289504 DOI: 10.1007/s00425-023-04317-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 12/23/2023] [Indexed: 02/01/2024]
Abstract
MAIN CONCLUSION Nonsense-mediated mRNA decay in eukaryotes is vital to cellular homeostasis. Further knowledge of its putative role in plant RNA metabolism under stress is pivotal to developing fitness-optimizing strategies. Nonsense-mediated mRNA decay (NMD), part of the mRNA surveillance pathway, is an evolutionarily conserved form of gene regulation in all living organisms. Degradation of mRNA-bearing premature termination codons and regulation of physiological RNA levels highlight NMD's role in shaping the cellular transcriptome. Initially regarded as purely a tool for cellular RNA quality control, NMD is now considered to mediate various aspects of plant developmental processes and responses to environmental changes. Here we offer a basic understanding of NMD in eukaryotes by explaining the concept of premature termination codon recognition and NMD complex formation. We also provide a detailed overview of the NMD mechanism and its role in gene regulation. The potential role of effectors, including ABCE1, in ribosome recycling during the translation process is also explained. Recent reports of alternatively spliced variants of corresponding genes targeted by NMD in Arabidopsis thaliana are provided in tabular format. Detailed figures are also provided to clarify the NMD concept in plants. In particular, accumulating evidence shows that NMD can serve as a novel alternative strategy for genetic manipulation and can help design RNA-based therapies to combat stress in plants. A key point of emphasis is its function as a gene regulatory mechanism as well as its dynamic regulation by environmental and developmental factors. Overall, a detailed molecular understanding of the NMD mechanism can lead to further diverse applications, such as improving cellular homeostasis in living organisms.
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Affiliation(s)
- Rashmita Luha
- Department of Botany, School for Basic Sciences, Central University of Punjab, Bathinda, India
- Centre for Biosystems Science and Engineering, Indian Institute of Science Bangalore, Bangaluru, India
| | - Varnika Rana
- Department of Botany, School for Basic Sciences, Central University of Punjab, Bathinda, India
| | - Alexander Vainstein
- Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Vinay Kumar
- Department of Botany, School for Basic Sciences, Central University of Punjab, Bathinda, India.
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2
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Shan LY, Tian Y, Liu WX, Fan HT, Li FG, Liu WJ, Li A, Shen W, Sun QY, Liu YB, Zhou Y, Zhang T. LSM14B controls oocyte mRNA storage and stability to ensure female fertility. Cell Mol Life Sci 2023; 80:247. [PMID: 37578641 PMCID: PMC10425512 DOI: 10.1007/s00018-023-04898-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Revised: 07/07/2023] [Accepted: 07/24/2023] [Indexed: 08/15/2023]
Abstract
Controlled mRNA storage and stability is essential for oocyte meiosis and early embryonic development. However, how to regulate mRNA storage and stability in mammalian oogenesis remains elusive. Here we showed that LSM14B, a component of membraneless compartments including P-body-like granules and mitochondria-associated ribonucleoprotein domain (MARDO) in germ cell, is indispensable for female fertility. To reveal loss of LSM14B disrupted primordial follicle assembly and caused mRNA reduction in non-growing oocytes, which was concomitant with the impaired assembly of P-body-like granules. 10× Genomics single-cell RNA-sequencing and immunostaining were performed. Meanwhile, we conducted RNA-seq analysis of GV-stage oocytes and found that Lsm14b deficiency not only impaired the maternal mRNA accumulation but also disrupted the translation in fully grown oocytes, which was closely associated with dissolution of MARDO components. Moreover, Lsm14b-deficient oocytes reassembled a pronucleus containing decondensed chromatin after extrusion of the first polar body, through compromising the activation of maturation promoting factor, while the defects were restored via WEE1/2 inhibitor. Together, our findings reveal that Lsm14b plays a pivotal role in mammalian oogenesis by specifically controlling of oocyte mRNA storage and stability.
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Affiliation(s)
- Li-Ying Shan
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock (R2BGL), College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Yu Tian
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock (R2BGL), College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Wen-Xiang Liu
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock (R2BGL), College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Hai-Tao Fan
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock (R2BGL), College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Feng-Guo Li
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock (R2BGL), College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Wen-Juan Liu
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock (R2BGL), College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
| | - Ang Li
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock (R2BGL), College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China
- Fertility Preservation Lab, Guangdong-Hong Kong Metabolism & Reproduction Joint Laboratory, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, 510317, China
| | - Wei Shen
- College of Life Sciences, Institute of Reproductive Sciences, Qingdao Agricultural University, Qingdao, 266109, China
| | - Qing-Yuan Sun
- Fertility Preservation Lab, Guangdong-Hong Kong Metabolism & Reproduction Joint Laboratory, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, 510317, China
| | - Yong-Bin Liu
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock (R2BGL), College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China.
| | - Yang Zhou
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock (R2BGL), College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China.
| | - Teng Zhang
- State Key Laboratory of Reproductive Regulation and Breeding of Grassland Livestock (R2BGL), College of Life Sciences, Inner Mongolia University, Hohhot, 010070, China.
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3
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Hernández-Elvira M, Sunnerhagen P. Post-transcriptional regulation during stress. FEMS Yeast Res 2022; 22:6585650. [PMID: 35561747 PMCID: PMC9246287 DOI: 10.1093/femsyr/foac025] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 04/25/2022] [Accepted: 05/10/2022] [Indexed: 11/12/2022] Open
Abstract
To remain competitive, cells exposed to stress of varying duration, rapidity of onset, and intensity, have to balance their expenditure on growth and proliferation versus stress protection. To a large degree dependent on the time scale of stress exposure, the different levels of gene expression control: transcriptional, post-transcriptional and post-translational, will be engaged in stress responses. The post-transcriptional level is appropriate for minute-scale responses to transient stress, and for recovery upon return to normal conditions. The turnover rate, translational activity, covalent modifications, and subcellular localisation of RNA species are regulated under stress by multiple cellular pathways. The interplay between these pathways is required to achieve the appropriate signalling intensity and prevent undue triggering of stress-activated pathways at low stress levels, avoid overshoot, and down-regulate the response in a timely fashion. As much of our understanding of post-transcriptional regulation has been gained in yeast, this review is written with a yeast bias, but attempts to generalise to other eukaryotes. It summarises aspects of how post-transcriptional events in eukaryotes mitigate short-term environmental stresses, and how different pathways interact to optimise the stress response under shifting external conditions.
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Affiliation(s)
- Mariana Hernández-Elvira
- Department of Chemistry and Molecular Biology, Lundberg Laboratory, University of Gothenburg, P.O. Box 462, S-405 30 Göteborg, Sweden
| | - Per Sunnerhagen
- Department of Chemistry and Molecular Biology, Lundberg Laboratory, University of Gothenburg, P.O. Box 462, S-405 30 Göteborg, Sweden
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4
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Nedelsky NB, Taylor JP. Pathological phase transitions in ALS-FTD impair dynamic RNA-protein granules. RNA (NEW YORK, N.Y.) 2022; 28:97-113. [PMID: 34706979 PMCID: PMC8675280 DOI: 10.1261/rna.079001.121] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The genetics of human disease serves as a robust and unbiased source of insight into human biology, both revealing fundamental cellular processes and exposing the vulnerabilities associated with their dysfunction. Over the last decade, the genetics of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) have epitomized this concept, as studies of ALS-FTD-causing mutations have yielded fundamental discoveries regarding the role of biomolecular condensation in organizing cellular contents while implicating disturbances in condensate dynamics as central drivers of neurodegeneration. Here we review this genetic evidence, highlight its intersection with patient pathology, and discuss how studies in model systems have revealed a role for aberrant condensation in neuronal dysfunction and death. We detail how multiple, distinct types of disease-causing mutations promote pathological phase transitions that disturb the dynamics and function of ribonucleoprotein (RNP) granules. Dysfunction of RNP granules causes pleiotropic defects in RNA metabolism and can drive the evolution of these structures to end-stage pathological inclusions characteristic of ALS-FTD. We propose that aberrant phase transitions of these complex condensates in cells provide a parsimonious explanation for the widespread cellular abnormalities observed in ALS as well as certain histopathological features that characterize late-stage disease.
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Affiliation(s)
- Natalia B Nedelsky
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
| | - J Paul Taylor
- Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
- Howard Hughes Medical Institute, Chevy Chase, Maryland 20815, USA
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5
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Morris C, Cluet D, Ricci EP. Ribosome dynamics and mRNA turnover, a complex relationship under constant cellular scrutiny. WILEY INTERDISCIPLINARY REVIEWS. RNA 2021; 12:e1658. [PMID: 33949788 PMCID: PMC8519046 DOI: 10.1002/wrna.1658] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 03/26/2021] [Accepted: 03/26/2021] [Indexed: 12/01/2022]
Abstract
Eukaryotic gene expression is closely regulated by translation and turnover of mRNAs. Recent advances highlight the importance of translation in the control of mRNA degradation, both for aberrant and apparently normal mRNAs. During translation, the information contained in mRNAs is decoded by ribosomes, one codon at a time, and tRNAs, by specifically recognizing codons, translate the nucleotide code into amino acids. Such a decoding step does not process regularly, with various obstacles that can hinder ribosome progression, then leading to ribosome stalling or collisions. The progression of ribosomes is constantly monitored by the cell which has evolved several translation-dependent mRNA surveillance pathways, including nonsense-mediated decay (NMD), no-go decay (NGD), and non-stop decay (NSD), to degrade certain problematic mRNAs and the incomplete protein products. Recent progress in sequencing and ribosome profiling has made it possible to discover new mechanisms controlling ribosome dynamics, with numerous crosstalks between translation and mRNA decay. We discuss here various translation features critical for mRNA decay, with particular focus on current insights from the complexity of the genetic code and also the emerging role for the ribosome as a regulatory hub orchestrating mRNA decay, quality control, and stress signaling. Even if the interplay between mRNA translation and degradation is no longer to be demonstrated, a better understanding of their precise coordination is worthy of further investigation. This article is categorized under: RNA Turnover and Surveillance > Regulation of RNA Stability Translation > Translation Regulation RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes.
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Affiliation(s)
- Christelle Morris
- Laboratory of Biology and Modeling of the CellUniversité de Lyon, ENS de Lyon, Université Claude Bernard, CNRS UMR 5239, Inserm U1293LyonFrance
| | - David Cluet
- Laboratory of Biology and Modeling of the CellUniversité de Lyon, ENS de Lyon, Université Claude Bernard, CNRS UMR 5239, Inserm U1293LyonFrance
| | - Emiliano P. Ricci
- Laboratory of Biology and Modeling of the CellUniversité de Lyon, ENS de Lyon, Université Claude Bernard, CNRS UMR 5239, Inserm U1293LyonFrance
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6
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Lee PJ, Yang S, Sun Y, Guo JU. Regulation of nonsense-mediated mRNA decay in neural development and disease. J Mol Cell Biol 2021; 13:269-281. [PMID: 33783512 PMCID: PMC8339359 DOI: 10.1093/jmcb/mjab022] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 01/27/2021] [Accepted: 02/05/2021] [Indexed: 11/26/2022] Open
Abstract
Eukaryotes have evolved a variety of mRNA surveillance mechanisms to detect and degrade aberrant mRNAs with potential deleterious outcomes. Among them, nonsense-mediated mRNA decay (NMD) functions not only as a quality control mechanism targeting aberrant mRNAs containing a premature termination codon but also as a posttranscriptional gene regulation mechanism targeting numerous physiological mRNAs. Despite its well-characterized molecular basis, the regulatory scope and biological functions of NMD at an organismal level are incompletely understood. In humans, mutations in genes encoding core NMD factors cause specific developmental and neurological syndromes, suggesting a critical role of NMD in the central nervous system. Here, we review the accumulating biochemical and genetic evidence on the developmental regulation and physiological functions of NMD as well as an emerging role of NMD dysregulation in neurodegenerative diseases.
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Affiliation(s)
- Paul Jongseo Lee
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA.,Interdepartmental Neuroscience Program, Yale University, New Haven, CT 06520, USA
| | - Suzhou Yang
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA.,Interdepartmental Neuroscience Program, Yale University, New Haven, CT 06520, USA
| | - Yu Sun
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Junjie U Guo
- Department of Neuroscience, Yale University School of Medicine, New Haven, CT 06520, USA.,Interdepartmental Neuroscience Program, Yale University, New Haven, CT 06520, USA
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7
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Moghadamnia F, Ghoraeian P, Minaeian S, Talebi A, Farsi F, Akbari A. MicroRNA Expression and Correlation with mRNA Levels of Colorectal Cancer-Related Genes. J Gastrointest Cancer 2020; 51:271-279. [PMID: 31102171 DOI: 10.1007/s12029-019-00249-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
INTRODUCTION MicroRNAs (miRNAs), as a family of non-coding RNAs, have opened a new window in cancer biology and transcriptome. It has been revealed that miRNAs post-transcriptionally regulate the gene expression and involve in colorectal cancer (CRC) development and progression. Our aim was to examine the differential expression of miRNAs in a CRC and to correlate their expression levels with mRNA levels of CRC-related genes (K-ras, APC, p53). MATERIALS AND METHODS Seventy-two colorectal tumor tissues from patients with newly diagnosed CRC and 72 matched normal adjacent tissues were analyzed. Relative expression of seven CRC-related miRNAs (miR-21, miR-31, miR-20a, miR-133b, and miR-145, miR-135b and let-7g) and three CRC-related genes (K-ras, APC, p53) was detected using the SYBR Green quantitative real-time PCR technique. The correlation between gene expression levels and clinicopathological features was evaluated. RESULTS Our results showed a significant difference between the two groups for the expression level of miR-21, miR-31, miR-145, and miR-20a (P < 0.001). Also, a significant difference between the two groups for the expression level of K-ras was found (P < 0.001). Further analysis revealed an inverse significant correlation between miR-145 and K-ras (R2 = 0.662, P < 0.001), while a positive correlation was observed between miR-21 and K-ras (R2 = 0.732, P < 0.001). CONCLUSION Dysregulation of miRNAs and correlation with molecular signaling pathways designated a biological role for miRNAs in various cellular mechanisms underlying CRC. On the other hand, the pattern of miRNAs expression and its correlation with transcriptional status are helpful to discovery biomarkers and design therapeutics for CRC.
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Affiliation(s)
- Farahnaz Moghadamnia
- Department of Genetics, Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran
| | - Pegah Ghoraeian
- Department of Genetics, Tehran Medical Sciences Branch, Islamic Azad University, Tehran, Iran
| | - Sara Minaeian
- Institute of Immunology and Infectious Diseases, Antimicrobial Resistance Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Atefeh Talebi
- Colorectal Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Farnaz Farsi
- Department of Nutrition, School of Public Health, Iran University of Medical Sciences, Tehran, Iran
| | - Abolfazl Akbari
- Colorectal Research Center, Iran University of Medical Sciences, Tehran, Iran. .,Colorectal Research Center, Rasoul-e- Akram Hospital, Sattarkhan Ave, Niyayesh St, Tehran, Iran.
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8
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Kurosaki T, Popp MW, Maquat LE. Quality and quantity control of gene expression by nonsense-mediated mRNA decay. Nat Rev Mol Cell Biol 2020; 20:406-420. [PMID: 30992545 DOI: 10.1038/s41580-019-0126-2] [Citation(s) in RCA: 446] [Impact Index Per Article: 111.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) is one of the best characterized and most evolutionarily conserved cellular quality control mechanisms. Although NMD was first found to target one-third of mutated, disease-causing mRNAs, it is now known to also target ~10% of unmutated mammalian mRNAs to facilitate appropriate cellular responses - adaptation, differentiation or death - to environmental changes. Mutations in NMD genes in humans are associated with intellectual disability and cancer. In this Review, we discuss how NMD serves multiple purposes in human cells by degrading both mutated mRNAs to protect the integrity of the transcriptome and normal mRNAs to control the quantities of unmutated transcripts.
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Affiliation(s)
- Tatsuaki Kurosaki
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY, USA.,Center for RNA Biology, University of Rochester, Rochester, NY, USA
| | - Maximilian W Popp
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY, USA.,Center for RNA Biology, University of Rochester, Rochester, NY, USA
| | - Lynne E Maquat
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, NY, USA. .,Center for RNA Biology, University of Rochester, Rochester, NY, USA.
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9
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Aznarez I, Nomakuchi TT, Tetenbaum-Novatt J, Rahman MA, Fregoso O, Rees H, Krainer AR. Mechanism of Nonsense-Mediated mRNA Decay Stimulation by Splicing Factor SRSF1. Cell Rep 2019; 23:2186-2198. [PMID: 29768215 PMCID: PMC5999336 DOI: 10.1016/j.celrep.2018.04.039] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 02/20/2018] [Accepted: 04/06/2018] [Indexed: 11/25/2022] Open
Abstract
The splicing factor SRSF1 promotes nonsense-mediated mRNA decay (NMD), a quality control mechanism that degrades mRNAs with premature termination codons (PTCs). Here we show that transcript-bound SRSF1 increases the binding of NMD factor UPF1 to mRNAs while in, or associated with, the nucleus, bypassing UPF2 recruitment and promoting NMD. SRSF1 promotes NMD when positioned downstream of a PTC, which resembles the mode of action of exon junction complex (EJC) and NMD factors. Moreover, splicing and/or EJC deposition increase the effect of SRSF1 on NMD. Lastly, SRSF1 enhances NMD of PTC-containing endogenous transcripts that result from various events. Our findings reveal an alternative mechanism for UPF1 recruitment, uncovering an additional connection between splicing and NMD. SRSF1’s role in the mRNA’s journey from splicing to decay has broad implications for gene expression regulation and genetic diseases.
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Affiliation(s)
- Isabel Aznarez
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | | | | | | | - Oliver Fregoso
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Holly Rees
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Adrian R Krainer
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA.
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10
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Wang Y, Shen W, Liang XH, Crooke ST. Phosphorothioate Antisense Oligonucleotides Bind P-Body Proteins and Mediate P-Body Assembly. Nucleic Acid Ther 2019; 29:343-358. [PMID: 31429620 DOI: 10.1089/nat.2019.0806] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Antisense oligonucleotides (ASOs) regulate gene expression by binding to complementary target RNA, and ASOs can be designed to take advantage of a growing array of post RNA binding molecular mechanisms. Intracellular trafficking of ASOs influences their efficacy. We have identified a number of membrane-less structures in the nucleus, nucleolus, and cytoplasm where phosphorothioate-modified ASOs (PS-ASOs) accumulate and have shown that PS-ASOs can induce the formation of new nuclear structures such as PS-bodies and paraspeckle-like structures. In this study, we report that PS-ASOs can localize to cytoplasmic processing bodies (P-bodies) and increase the number of P-bodies in cells. The antisense activity of PS-ASOs was not affected by the absence of essential P-body assembly proteins DDX6 and LSm14A. Moreover, the effects of PS-ASOs on P-body assembly were independent of their antisense activities. The phosphorothioate modification stabilizes the association between ASOs and cellular proteins and is essential for the P-body localization of ASOs. Since PS-ASOs bind to major P-body components, PS-ASOs may serve as scaffolds for P-body formation. Taken together, these results indicate that interactions of PS-ASO with proteins, rather than antisense activities, are essential for the dynamic interplay between PS-ASOs and P-bodies.
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Affiliation(s)
- Ying Wang
- Department of Core Antisense Research, Ionis Pharmaceuticals, Inc., Carlsbad, California
| | - Wen Shen
- Department of Core Antisense Research, Ionis Pharmaceuticals, Inc., Carlsbad, California
| | - Xue-Hai Liang
- Department of Core Antisense Research, Ionis Pharmaceuticals, Inc., Carlsbad, California
| | - Stanley T Crooke
- Department of Core Antisense Research, Ionis Pharmaceuticals, Inc., Carlsbad, California
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11
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Pitchiaya S, Mourao MDA, Jalihal AP, Xiao L, Jiang X, Chinnaiyan AM, Schnell S, Walter NG. Dynamic Recruitment of Single RNAs to Processing Bodies Depends on RNA Functionality. Mol Cell 2019; 74:521-533.e6. [PMID: 30952514 DOI: 10.1016/j.molcel.2019.03.001] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 12/21/2018] [Accepted: 02/27/2019] [Indexed: 11/19/2022]
Abstract
Cellular RNAs often colocalize with cytoplasmic, membrane-less ribonucleoprotein (RNP) granules enriched for RNA-processing enzymes, termed processing bodies (PBs). Here we track the dynamic localization of individual miRNAs, mRNAs, and long non-coding RNAs (lncRNAs) to PBs using intracellular single-molecule fluorescence microscopy. We find that unused miRNAs stably bind to PBs, whereas functional miRNAs, repressed mRNAs, and lncRNAs both transiently and stably localize within either the core or periphery of PBs, albeit to different extents. Consequently, translation potential and 3' versus 5' placement of miRNA target sites significantly affect the PB localization dynamics of mRNAs. Using computational modeling and supporting experimental approaches, we show that partitioning in the PB phase attenuates mRNA silencing, suggesting that physiological mRNA turnover occurs predominantly outside of PBs. Instead, our data support a PB role in sequestering unused miRNAs for surveillance and provide a framework for investigating the dynamic assembly of RNP granules by phase separation at single-molecule resolution.
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Affiliation(s)
- Sethuramasundaram Pitchiaya
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA; Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA; Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA; Comprehensive Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA.
| | - Marcio D A Mourao
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA; Consulting for Statistics, Computing and Analytics Research, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Ameya P Jalihal
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
| | - Lanbo Xiao
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA
| | - Xia Jiang
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA
| | - Arul M Chinnaiyan
- Michigan Center for Translational Pathology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA; Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA; Comprehensive Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA; Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Santiago Schnell
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI 48109-1055, USA
| | - Nils G Walter
- Single Molecule Analysis Group, Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA.
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12
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Karousis ED, Mühlemann O. Nonsense-Mediated mRNA Decay Begins Where Translation Ends. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a032862. [PMID: 29891560 DOI: 10.1101/cshperspect.a032862] [Citation(s) in RCA: 128] [Impact Index Per Article: 25.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Nonsense-mediated mRNA decay (NMD) is arguably the best-studied eukaryotic messenger RNA (mRNA) surveillance pathway, yet fundamental questions concerning the molecular mechanism of target RNA selection remain unsolved. Besides degrading defective mRNAs harboring premature termination codons (PTCs), NMD also targets many mRNAs encoding functional full-length proteins. Thus, NMD impacts on a cell's transcriptome and is implicated in a range of biological processes that affect a broad spectrum of cellular homeostasis. Here, we focus on the steps involved in the recognition of NMD targets and the activation of NMD. We summarize the accumulating evidence that tightly links NMD to translation termination and we further discuss the recruitment and activation of the mRNA degradation machinery and the regulation of this complex series of events. Finally, we review emerging ideas concerning the mechanistic details of NMD activation and the potential role of NMD as a general surveyor of translation efficacy.
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Affiliation(s)
- Evangelos D Karousis
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland
| | - Oliver Mühlemann
- Department of Chemistry and Biochemistry, University of Bern, CH-3012 Bern, Switzerland
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13
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Sadej R, Lu X, Turczyk L, Novitskaya V, Lopez-Clavijo AF, Kordek R, Potemski P, Wakelam MJO, Romanska-Knight H, Berditchevski F. CD151 regulates expression of FGFR2 in breast cancer cells via PKC-dependent pathways. J Cell Sci 2018; 131:jcs220640. [PMID: 30257985 DOI: 10.1242/jcs.220640] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 09/17/2018] [Indexed: 11/20/2022] Open
Abstract
Expression of the tetraspanin CD151 is frequently upregulated in epithelial malignancies and correlates with poor prognosis. Here, we report that CD151 is involved in regulation of the expression of fibroblast growth factor receptor 2 (FGFR2). Depletion of CD151 in breast cancer cells resulted in an increased level of FGFR2. Accordingly, an inverse correlation between CD151 and FGFR2 was observed in breast cancer tissues. CD151-dependent regulation of the FGFR2 expression relies on post-transcriptional mechanisms involving HuR (also known as ELAVL1), a multifunctional RNA-binding protein, and the assembly of processing bodies (P-bodies). Depletion of CD151 correlated with inhibition of PKC, a well-established downstream target of CD151. Accordingly, the levels of dialcylglycerol species were decreased in CD151-negative cells, and inhibition of PKC resulted in the increased expression of FGFR2. Whereas expression of FGFR2 itself did not correlate with any of the clinicopathological data, we found that FGFR2-/CD151+ patients were more likely to have developed lymph node metastasis. Conversely, FGFR2-/CD151- patients demonstrated better overall survival. These results illustrate functional interdependency between CD151 complexes and FGFR2, and suggest a previously unsuspected role of CD151 in breast tumorigenesis.
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Affiliation(s)
- Rafal Sadej
- Department of Molecular Enzymology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307 Gdańsk, Poland
| | - Xiaohong Lu
- Institute of Cancer and Genomic Sciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Lukasz Turczyk
- Department of Molecular Enzymology, Intercollegiate Faculty of Biotechnology, University of Gdansk and Medical University of Gdansk, Abrahama 58, 80-307 Gdańsk, Poland
| | - Vera Novitskaya
- Institute of Cancer and Genomic Sciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | | | - Radzisław Kordek
- Department of Pathology and Chemotherapy, Medical University of Łódź, 92-213 Łódź, Poland
| | - Piotr Potemski
- Department of Pathology and Chemotherapy, Medical University of Łódź, 92-213 Łódź, Poland
| | | | - Hanna Romanska-Knight
- Department of Pathology and Chemotherapy, Medical University of Łódź, 92-213 Łódź, Poland
| | - Fedor Berditchevski
- Institute of Cancer and Genomic Sciences, The University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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Chicois C, Scheer H, Garcia S, Zuber H, Mutterer J, Chicher J, Hammann P, Gagliardi D, Garcia D. The UPF1 interactome reveals interaction networks between RNA degradation and translation repression factors in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2018; 96:119-132. [PMID: 29983000 DOI: 10.1111/tpj.14022] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Revised: 06/20/2018] [Accepted: 06/26/2018] [Indexed: 06/08/2023]
Abstract
The RNA helicase UP-FRAMESHIFT (UPF1) is a key factor of nonsense-mediated decay (NMD), a mRNA decay pathway involved in RNA quality control and in the fine-tuning of gene expression. UPF1 recruits UPF2 and UPF3 to constitute the NMD core complex, which is conserved across eukaryotes. No other components of UPF1-containing ribonucleoproteins (RNPs) are known in plants, despite its key role in regulating gene expression. Here, we report the identification of a large set of proteins that co-purify with the Arabidopsis UPF1, either in an RNA-dependent or RNA-independent manner. We found that like UPF1, several of its co-purifying proteins have a dual localization in the cytosol and in P-bodies, which are dynamic structures formed by the condensation of translationally repressed mRNPs. Interestingly, more than half of the proteins of the UPF1 interactome also co-purify with DCP5, a conserved translation repressor also involved in P-body formation. We identified a terminal nucleotidyltransferase, ribonucleases and several RNA helicases among the most significantly enriched proteins co-purifying with both UPF1 and DCP5. Among these, RNA helicases are the homologs of DDX6/Dhh1, known as translation repressors in humans and yeast, respectively. Overall, this study reports a large set of proteins associated with the Arabidopsis UPF1 and DCP5, two components of P-bodies, and reveals an extensive interaction network between RNA degradation and translation repression factors. Using this resource, we identified five hitherto unknown components of P-bodies in plants, pointing out the value of this dataset for the identification of proteins potentially involved in translation repression and/or RNA degradation.
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Affiliation(s)
- Clara Chicois
- Institut de biologie moléculaire des plantes (IBMP), CNRS, Université de Strasbourg, 67000, Strasbourg, France
| | - Hélène Scheer
- Institut de biologie moléculaire des plantes (IBMP), CNRS, Université de Strasbourg, 67000, Strasbourg, France
| | - Shahïnez Garcia
- Institut de biologie moléculaire des plantes (IBMP), CNRS, Université de Strasbourg, 67000, Strasbourg, France
| | - Hélène Zuber
- Institut de biologie moléculaire des plantes (IBMP), CNRS, Université de Strasbourg, 67000, Strasbourg, France
| | - Jérôme Mutterer
- Institut de biologie moléculaire des plantes (IBMP), CNRS, Université de Strasbourg, 67000, Strasbourg, France
| | - Johana Chicher
- Plateforme Protéomique Strasbourg-Esplanade, CNRS, Université de Strasbourg, 67000, Strasbourg, France
| | - Philippe Hammann
- Plateforme Protéomique Strasbourg-Esplanade, CNRS, Université de Strasbourg, 67000, Strasbourg, France
| | - Dominique Gagliardi
- Institut de biologie moléculaire des plantes (IBMP), CNRS, Université de Strasbourg, 67000, Strasbourg, France
| | - Damien Garcia
- Institut de biologie moléculaire des plantes (IBMP), CNRS, Université de Strasbourg, 67000, Strasbourg, France
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15
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Standart N, Weil D. P-Bodies: Cytosolic Droplets for Coordinated mRNA Storage. Trends Genet 2018; 34:612-626. [PMID: 29908710 DOI: 10.1016/j.tig.2018.05.005] [Citation(s) in RCA: 140] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 05/14/2018] [Accepted: 05/17/2018] [Indexed: 12/21/2022]
Abstract
P-bodies (PBs) are cytosolic RNP granules that are conserved among eukaryotic organisms. In the past few years, major progress has been made in understanding the biochemical and biophysical mechanisms that lead to their formation. However, whether they play a role in mRNA storage or decay remains actively debated. P-bodies were recently isolated from human cells by a novel fluorescence-activated particle sorting (FAPS) approach that enabled the characterization of their protein and RNA content, providing new insights into their function. Together with recent innovative imaging studies, these new data show that mammalian PBs are primarily involved not in RNA decay but rather in the coordinated storage of mRNAs encoding regulatory functions. These small cytoplasmic droplets could thus be important for cell adaptation to the environment.
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Affiliation(s)
- Nancy Standart
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK
| | - Dominique Weil
- Sorbonne Université, CNRS, Institut de Biologie Paris-Seine (IBPS), Laboratoire de Biologie du Développement, F-75005 Paris, France.
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16
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MacDonald CC, Grozdanov PN. Nonsense in the testis: multiple roles for nonsense-mediated decay revealed in male reproduction. Biol Reprod 2018; 96:939-947. [PMID: 28444146 PMCID: PMC5803779 DOI: 10.1093/biolre/iox033] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 04/20/2017] [Indexed: 01/23/2023] Open
Abstract
Nonsense-mediated mRNA decay, or NMD, is a quality control mechanism that identifies cytoplasmic mRNAs containing translational termination (stop) codons in specific contexts—either premature termination codons or unusually long 3΄ untranslated regions (UTRs)—and targets them for degradation. In recent studies, researchers in different labs have knocked out important genes involved in NMD, the up-frameshift genes Upf2 and Upf3a, and one component of chromatoid bodies, the Tudor domain-containing protein Tdrd6, and examined the consequences for spermatogenesis. Disruption of Upf2 during early stages of spermatogenesis resulted in disappearance of nearly all spermatogenic cells through loss of NMD. However, disruption of Upf2 during postmeiotic stages resulted in decreased long 3΄ UTR-mediated NMD but no interruption of exon junction-associated NMD. This difference in NMD targeting is possibly due to increased expression of Upf3a in postmeiotic germ cells that antagonizes the functions of Upf3b and somehow favors long 3΄ UTR-mediated NMD. Tying these all together, loss of Tdrd6, a structural component of the germ cell-specific cytoplasmic structures called chromatoid bodies, also resulted in loss of long 3΄ UTR-mediated NMD by interfering with UPF1/UPF2 interactions, delocalizing UPF1, and destroying chromatoid body integrity. These results suggest that chromatoid bodies play a specialized role in modulating the NMD machinery in postmeiotic spermatids.
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Affiliation(s)
- Clinton C. MacDonald
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
- Correspondence: Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, 3601 4th Street, Lubbock, TX 79430-6540, USA. Tel: +1-806-743-2524; Fax: +1-806-743-2990; E-mail:
| | - Petar N. Grozdanov
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas
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Diverse Strategies Used by Picornaviruses to Escape Host RNA Decay Pathways. Viruses 2016; 8:v8120335. [PMID: 27999393 PMCID: PMC5192396 DOI: 10.3390/v8120335] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Revised: 12/07/2016] [Accepted: 12/09/2016] [Indexed: 12/24/2022] Open
Abstract
To successfully replicate, viruses protect their genomic material from degradation by the host cell. RNA viruses must contend with numerous destabilizing host cell processes including mRNA decay pathways and viral RNA (vRNA) degradation resulting from the antiviral response. Members of the Picornaviridae family of small RNA viruses have evolved numerous diverse strategies to evade RNA decay, including incorporation of stabilizing elements into vRNA and re-purposing host stability factors. Viral proteins are deployed to disrupt and inhibit components of the decay machinery and to redirect decay machinery to the advantage of the virus. This review summarizes documented interactions of picornaviruses with cellular RNA decay pathways and processes.
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18
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Fanourgakis G, Lesche M, Akpinar M, Dahl A, Jessberger R. Chromatoid Body Protein TDRD6 Supports Long 3' UTR Triggered Nonsense Mediated mRNA Decay. PLoS Genet 2016; 12:e1005857. [PMID: 27149095 PMCID: PMC4858158 DOI: 10.1371/journal.pgen.1005857] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 01/20/2016] [Indexed: 02/08/2023] Open
Abstract
Chromatoid bodies (CBs) are spermiogenesis-specific organelles of largely unknown function. CBs harbor various RNA species, RNA-associated proteins and proteins of the tudor domain family like TDRD6, which is required for a proper CB architecture. Proteome analysis of purified CBs revealed components of the nonsense-mediated mRNA decay (NMD) machinery including UPF1. TDRD6 is essential for UPF1 localization to CBs, for UPF1-UPF2 and UPF1-MVH interactions. Upon removal of TDRD6, the association of several mRNAs with UPF1 and UPF2 is disturbed, and the long 3’ UTR-stimulated but not the downstream exon-exon junction triggered pathway of NMD is impaired. Reduced association of the long 3’ UTR mRNAs with UPF1 and UPF2 correlates with increased stability and enhanced translational activity. Thus, we identified TDRD6 within CBs as required for mRNA degradation, specifically the extended 3’ UTR-triggered NMD pathway, and provide evidence for the requirement of NMD in spermiogenesis. This function depends on TDRD6-promoted assembly of mRNA and decay enzymes in CBs. Tudor-domain containing protein 6 (TDRD6) is a central component of the chromatoid body (CB) in male germ cells. Chromatoid bodies, which are present in spermatids, contain RNA and protein, are not enclosed by membranes, and typically reside close to the nucleus. Without TDRD6, a much distorted CB structure is observed, and this work asked for the functional contribution of TDRD6 to spermatids. We found that TDRD6 is required for localization of an RNA degradation machinery to the CB. This so-called nonsense mediated decay (NMD) machinery, known from somatic cells, destroys mRNAs that feature premature stop codons. Absence of TDRD6 significantly impairs one specific mechanism of NMD, which depends on long 3’ untranslated regions of the transcripts. Thus, the CB component TDRD6 acts in the assembly of the NMD machinery in the CB.
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Affiliation(s)
- Grigorios Fanourgakis
- Institute of Physiological Chemistry, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Mathias Lesche
- Deep Sequencing Group SFB 655, Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Müge Akpinar
- Institute of Physiological Chemistry, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Andreas Dahl
- Deep Sequencing Group SFB 655, Biotechnology Center, Technische Universität Dresden, Dresden, Germany
| | - Rolf Jessberger
- Institute of Physiological Chemistry, Medical Faculty Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- * E-mail:
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19
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Membrane-association of mRNA decapping factors is independent of stress in budding yeast. Sci Rep 2016; 6:25477. [PMID: 27146487 PMCID: PMC4857118 DOI: 10.1038/srep25477] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 04/19/2016] [Indexed: 12/23/2022] Open
Abstract
Recent evidence has suggested that the degradation of mRNA occurs on translating ribosomes or alternatively within RNA granules called P bodies, which are aggregates whose core constituents are mRNA decay proteins and RNA. In this study, we examined the mRNA decapping proteins, Dcp1, Dcp2, and Dhh1, using subcellular fractionation. We found that decapping factors co-sediment in the polysome fraction of a sucrose gradient and do not alter their behaviour with stress, inhibition of translation or inhibition of the P body formation. Importantly, their localisation to the polysome fraction is independent of the RNA, suggesting that these factors may be constitutively localised to the polysome. Conversely, polysomal and post-polysomal sedimentation of the decapping proteins was abolished with the addition of a detergent, which shifts the factors to the non-translating RNP fraction and is consistent with membrane association. Using a membrane flotation assay, we observed the mRNA decapping factors in the lower density fractions at the buoyant density of membrane-associated proteins. These observations provide further evidence that mRNA decapping factors interact with subcellular membranes, and we suggest a model in which the mRNA decapping factors interact with membranes to facilitate regulation of mRNA degradation.
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20
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Park J, Ahn S, Jayabalan AK, Ohn T, Koh HC, Hwang J. Insulin Signaling Augments eIF4E-Dependent Nonsense-Mediated mRNA Decay in Mammalian Cells. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2015; 1859:896-905. [PMID: 26708722 DOI: 10.1016/j.bbagrm.2015.12.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Revised: 12/14/2015] [Accepted: 12/17/2015] [Indexed: 12/13/2022]
Abstract
Nonsense-mediated mRNA decay (NMD) modulates the level of mRNA harboring a premature termination codon (PTC) in a translation-dependent manner. Inhibition of translation is known to impair NMD; however, few studies have investigated the correlation between enhanced translation and increased NMD. Here, we demonstrate that insulin signaling events increase translation, leading to an increase in NMD of eIF4E-bound transcripts. We provide evidence that (i) insulin-mediated enhancement of translation augments NMD and rapamycin abrogates this enhancement; (ii) an increase in AKT phosphorylation due to inhibition of PTEN facilitates NMD; (iii) insulin stimulation increases the binding of up-frameshift factor 1 (UPF1), most likely to eIF4E-bound PTC-containing transcripts; and (iv) insulin stimulation induces the colocalization of UPF1 and eIF4E in processing bodies. These results illustrate how extracellular signaling promotes the removal of eIF4E-bound NMD targets.
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Affiliation(s)
- Jungyun Park
- Graduate School for Biomedical Science & Engineering, FTC1202-8, Hanyang University, 222 Wangimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Seyoung Ahn
- Graduate School for Biomedical Science & Engineering, FTC1202-8, Hanyang University, 222 Wangimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea
| | - Aravinth K Jayabalan
- Department of Cellular and Molecular Medicine, College of Medicine, Chosun University, Gwangju, Republic of Korea
| | - Takbum Ohn
- Department of Cellular and Molecular Medicine, College of Medicine, Chosun University, Gwangju, Republic of Korea
| | - Hyun Chul Koh
- Department of Pharmacology, College of Medicine, Hanyang University, 222 Wangimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea.
| | - Jungwook Hwang
- Graduate School for Biomedical Science & Engineering, FTC1202-8, Hanyang University, 222 Wangimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea; Department of Medical Genetics, College of Medicine, FTC1202-8, Hanyang University, 222 Wangimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea.
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21
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Mocquet V, Durand S, Jalinot P. How Retroviruses Escape the Nonsense-Mediated mRNA Decay. AIDS Res Hum Retroviruses 2015; 31:948-58. [PMID: 26066561 DOI: 10.1089/aid.2014.0326] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Many posttranscriptional processes are known to regulate gene expression and some of them can act as an antiviral barrier. The nonsense-mediated mRNA decay (NMD) was first identified as an mRNA quality control pathway that triggers rapid decay of mRNA containing premature stop codons due to mutations. NMD is now considered as a general posttranscriptional regulation pathway controlling the expression of a large set of cellular genes. In addition to premature stop codons, many other features including alternative splicing, 5' uORF, long 3' UTR, selenocystein codons, and frameshift are able to promote NMD. Interestingly, many viral mRNAs exhibit some of these features suggesting that virus expression and replication might be sensitive to NMD. Several studies, including recent ones, have shown that this is the case for retroviruses; however, it also appears that retroviruses have developed strategies to overcome NMD in order to protect their genome and ensure a true expression of their genes. As a consequence of NMD inhibition, these viruses also affect the expression of host genes that are prone to NMD, and therefore can potentially trigger pathological effects on infected cells. Here, we review recent studies supporting this newly uncovered function of the NMD pathway as a defense barrier that viruses must overcome in order to replicate.
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Affiliation(s)
- Vincent Mocquet
- Laboratoire de Biologie Moléculaire de la Cellule, Unité Mixte de Recherche 5239, Centre National de la Recherche Scientifique , Ecole Normale Supérieure, Lyon, France
| | - Sebastien Durand
- Laboratoire de Biologie Moléculaire de la Cellule, Unité Mixte de Recherche 5239, Centre National de la Recherche Scientifique , Ecole Normale Supérieure, Lyon, France
| | - Pierre Jalinot
- Laboratoire de Biologie Moléculaire de la Cellule, Unité Mixte de Recherche 5239, Centre National de la Recherche Scientifique , Ecole Normale Supérieure, Lyon, France
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22
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Cytoplasmic mRNA turnover and ageing. Mech Ageing Dev 2015; 152:32-42. [PMID: 26432921 PMCID: PMC4710634 DOI: 10.1016/j.mad.2015.09.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 09/17/2015] [Accepted: 09/27/2015] [Indexed: 12/12/2022]
Abstract
We address the cytoplasmic mRNA decay processes that determine the mRNAs half-life. We briefly describe the major, evolutionary conserved, ageing pathways and mechanisms. We summarize critical findings that link mRNA turnover and ageing modulators.
Messenger RNA (mRNA) turnover that determines the lifetime of cytoplasmic mRNAs is a means to control gene expression under both normal and stress conditions, whereas its impact on ageing and age-related disorders has just become evident. Gene expression control is achieved at the level of the mRNA clearance as well as mRNA stability and accessibility to other molecules. All these processes are regulated by cis-acting motifs and trans-acting factors that determine the rates of translation and degradation of transcripts. Specific messenger RNA granules that harbor the mRNA decay machinery or various factors, involved in translational repression and transient storage of mRNAs, are also part of the mRNA fate regulation. Their assembly and function can be modulated to promote stress resistance to adverse conditions and over time affect the ageing process and the lifespan of the organism. Here, we provide insights into the complex relationships of ageing modulators and mRNA turnover mechanisms.
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Alrahbeni T, Sartor F, Anderson J, Miedzybrodzka Z, McCaig C, Müller B. Full UPF3B function is critical for neuronal differentiation of neural stem cells. Mol Brain 2015; 8:33. [PMID: 26012578 PMCID: PMC4445987 DOI: 10.1186/s13041-015-0122-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Accepted: 05/11/2015] [Indexed: 12/03/2022] Open
Abstract
Background Mutation in the UPF3B gene on chromosome X is implicated in neurodevelopmental disorders including X-linked intellectual disability, autism and schizophrenia. The protein UPF3B is involved in the nonsense-mediated mRNA decay pathway (NMD) that controls mRNA stability and functions in the prevention of the synthesis of truncated proteins. Results Here we show that NMD pathway components UPF3B and UPF1 are down-regulated during differentiation of neural stem cells into neurons. Using tethered function assays we found that UPF3B missense mutations described in families with neurodevelopmental disorders reduced the activity of UPF3B protein in NMD. In neural stem cells, UPF3B protein was detected in the cytoplasm and in the nucleus. Similarly in neurons, UPF3B protein was detected in neurites, the somatic cytoplasm and in the nucleus. In both cell types nuclear UPF3B protein was enriched in the nucleolus. Using GFP tagged UPF3B proteins we found that the missense mutations did not affect the cellular localisation. Expression of missense mutant UPF3B disturbed neuronal differentiation and reduced the complexity of the branching of neurites. Neuronal differentiation was similarly affected in the presence of the NMD inhibitor Amlexanox. The expression of mutant UPF3B proteins lead to a subtle increase in mRNA levels of selected NMD targets. Conclusions Together our findings indicate that, despite the down-regulation of NMD factors, functional NMD is critical for neuronal differentiation. We propose that the neurodevelopmental phenotype of UPF3B missense mutation is caused by impairment of NMD function altering neuronal differentiation. Electronic supplementary material The online version of this article (doi:10.1186/s13041-015-0122-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Tahani Alrahbeni
- University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK. .,Current address: Riyadh Colleges of Dentistry and Pharmacy, Olaya Campus, Riyadh, Saudi Arabia.
| | - Francesca Sartor
- University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK.
| | - Jihan Anderson
- University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK.
| | - Zosia Miedzybrodzka
- Medical Genetics, Polwarth Building, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK.
| | - Colin McCaig
- University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK.
| | - Berndt Müller
- University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, Scotland, UK.
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24
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Shah K, Cheng Y, Hahn B, Bridges R, Bradbury NA, Mueller DM. Synonymous codon usage affects the expression of wild type and F508del CFTR. J Mol Biol 2015; 427:1464-1479. [PMID: 25676312 DOI: 10.1016/j.jmb.2015.02.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 02/03/2015] [Accepted: 02/04/2015] [Indexed: 10/24/2022]
Abstract
The cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel composed of 1480 amino acids. The major mutation responsible for cystic fibrosis results in loss of amino acid residue, F508 (F508del). Loss of F508 in CFTR alters the folding pathway resulting in endoplasmic-reticulum-associated degradation. This study investigates the role of synonymous codon in the expression of CFTR and CFTR F508del in human HEK293 cells. DNA encoding the open reading frame (ORF) for CFTR containing synonymous codon replacements was expressed using a heterologous vector integrated into the genome. The results indicate that the codon usage greatly affects the expression of CFTR. While the promoter strength driving expression of the ORFs was largely unchanged and the mRNA half-lives were unchanged, the steady-state levels of the mRNA varied by as much as 30-fold. Experiments support that this apparent inconsistency is attributed to nonsense mediated decay independent of exon junction complex. The ratio of CFTR/mRNA indicates that mRNA containing native codons was more efficient in expressing mature CFTR as compared to mRNA containing synonymous high-expression codons. However, when F508del CFTR was expressed after codon optimization, a greater percentage of the protein escaped endoplasmic-reticulum-associated degradation resulting in considerable levels of mature F508del CFTR on the plasma membrane, which showed channel activity. These results indicate that codon usage has an effect on mRNA levels and protein expression, for CFTR, and likely on chaperone-assisted folding pathway, for F508del CFTR.
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Affiliation(s)
- Kalpit Shah
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University, The Chicago Medical School, North Chicago, IL 60064, USA; Department of Physiology and Biophysics, Rosalind Franklin University, The Chicago Medical School, North Chicago, IL 60064, USA
| | - Yi Cheng
- Department of Physiology and Biophysics, Rosalind Franklin University, The Chicago Medical School, North Chicago, IL 60064, USA
| | - Brian Hahn
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University, The Chicago Medical School, North Chicago, IL 60064, USA
| | - Robert Bridges
- Department of Physiology and Biophysics, Rosalind Franklin University, The Chicago Medical School, North Chicago, IL 60064, USA
| | - Neil A Bradbury
- Department of Physiology and Biophysics, Rosalind Franklin University, The Chicago Medical School, North Chicago, IL 60064, USA
| | - David M Mueller
- Department of Biochemistry and Molecular Biology, Rosalind Franklin University, The Chicago Medical School, North Chicago, IL 60064, USA.
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25
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Adjibade P, Mazroui R. Control of mRNA turnover: implication of cytoplasmic RNA granules. Semin Cell Dev Biol 2014; 34:15-23. [PMID: 24946962 DOI: 10.1016/j.semcdb.2014.05.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Accepted: 05/21/2014] [Indexed: 12/15/2022]
Abstract
The control of mRNA turnover is essential for the cell to rationalize its mRNA content both under physiological conditions and upon stress. Several mechanisms involved in the control of mRNA turnover have been elucidated. These include surveillance mechanisms such as nonsense-mediated decay, non-stop mediated decay and non-go-mediated decay that eliminate aberrant mRNAs, and regulatory mechanisms including AU-mediated decay, GU-mediated decay, and CDE-mediated decay that ensure mRNA plasticity. In general, the mechanisms of RNA decay rely on interactions between specific cis-acting RNA elements and selected RNA-binding proteins that either prevent the degradation of mRNA targets or induce the recruitment of decaying effectors leading to mRNA degradation. Formation of cytoplasmic RNA granules including processing bodies, stress granules, UV granules, and exosome granules have recently emerged as an additional mechanism that control mRNA turnover of selected mRNAs. Here we will review briefly review the main mechanisms that control mRNA decay and highlight possible implication of RNA granules in such mechanisms.
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Affiliation(s)
- Pauline Adjibade
- Centre de recherche du CHU de Québec, Département de biologie moléculaire, biochimie médicale et pathologie, Université Laval, Québec, PQ, Canada
| | - Rachid Mazroui
- Centre de recherche du CHU de Québec, Département de biologie moléculaire, biochimie médicale et pathologie, Université Laval, Québec, PQ, Canada.
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26
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Abstract
Cells use messenger RNAs (mRNAs) to ensure the accurate dissemination of genetic information encoded by DNA. Given that mRNAs largely direct the synthesis of a critical effector of cellular phenotype, i.e., proteins, tight regulation of both the quality and quantity of mRNA is a prerequisite for effective cellular homeostasis. Here, we review nonsense-mediated mRNA decay (NMD), which is the best-characterized posttranscriptional quality control mechanism that cells have evolved in their cytoplasm to ensure transcriptome fidelity. We use protein quality control as a conceptual framework to organize what is known about NMD, highlighting overarching similarities between these two polymer quality control pathways, where the protein quality control and NMD pathways intersect, and how protein quality control can suggest new avenues for research into mRNA quality control.
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Affiliation(s)
- Maximilian Wei-Lin Popp
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642;
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Kamenska A, Lu WT, Kubacka D, Broomhead H, Minshall N, Bushell M, Standart N. Human 4E-T represses translation of bound mRNAs and enhances microRNA-mediated silencing. Nucleic Acids Res 2013; 42:3298-313. [PMID: 24335285 PMCID: PMC3950672 DOI: 10.1093/nar/gkt1265] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
A key player in translation initiation is eIF4E, the mRNA 5' cap-binding protein. 4E-Transporter (4E-T) is a recently characterized eIF4E-binding protein, which regulates specific mRNAs in several developmental model systems. Here, we first investigated the role of its enrichment in P-bodies and eIF4E-binding in translational regulation in mammalian cells. Identification of the conserved C-terminal sequences that target 4E-T to P-bodies was enabled by comparison of vertebrate proteins with homologues in Drosophila (Cup and CG32016) and Caenorhabditis elegans by sequence and cellular distribution. In tether function assays, 4E-T represses bound mRNA translation, in a manner independent of these localization sequences, or of endogenous P-bodies. Quantitative polymerase chain reaction and northern blot analysis verified that bound mRNA remained intact and polyadenylated. Ectopic 4E-T reduces translation globally in a manner dependent on eIF4E binding its consensus Y30X4L site. In contrast, tethered 4E-T continued to repress translation when eIF4E-binding was prevented by mutagenesis of YX4L, and modestly enhanced the decay of bound mRNA, compared with wild-type 4E-T, mediated by increased binding of CNOT1/7 deadenylase subunits. As depleting 4E-T from HeLa cells increased steady-state translation, in part due to relief of microRNA-mediated silencing, this work demonstrates the conserved yet unconventional mechanism of 4E-T silencing of particular subsets of mRNAs.
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Affiliation(s)
- Anastasiia Kamenska
- Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB21QW, UK and MRC Toxicology Unit, University of Leicester, Lancaster Road, Leicester LE19HN, UK
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Cho H, Han S, Park OH, Kim YK. SMG1 regulates adipogenesis via targeting of staufen1-mediated mRNA decay. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:1276-87. [DOI: 10.1016/j.bbagrm.2013.10.004] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 10/23/2013] [Accepted: 10/25/2013] [Indexed: 12/21/2022]
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29
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Abstract
mRNA has become an important alternative to DNA as a tool for cell reprogramming. To be expressed, exogenous DNA must be transmitted through the cell cytoplasm and placed into the nucleus. In contrast, exogenous mRNA simply has to be delivered into the cytoplasm. This can result in a highly uniform transfection of the whole population of cells, an advantage that has not been observed with DNA transfer. The use of mRNA, instead of DNA, in medical applications increases protocol safety by abolishing the risk of transgene insertion into host genomes. In this chapter, we review the aspects of mRNA structure and function that are important for its "transgenic" behavior, such as the composition of mRNA molecules and complexes with RNA binding proteins, localization of mRNA in cytoplasmic compartments, translation, and the duration of mRNA expression. In immunotherapy, mRNA is employed in reprogramming of antigen presenting cells (vaccination) and cytolytic lymphocytes. Other applications include generation of induced pluripotent stem (iPS) cells, and genome engineering with modularly assembled nucleases. The most investigated applications of mRNA technology are also reviewed here.
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30
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Hooper C, Hilliker A. Packing them up and dusting them off: RNA helicases and mRNA storage. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2013; 1829:824-34. [PMID: 23528738 DOI: 10.1016/j.bbagrm.2013.03.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Revised: 03/16/2013] [Accepted: 03/18/2013] [Indexed: 12/31/2022]
Abstract
Cytoplasmic mRNA can be translated, translationally repressed, localized or degraded. Regulation of translation is an important step in control of gene expression and the cell can change whether and to what extent an mRNA is translated. If an mRNA is not translating, it will associate with translation repression factors; the mRNA can be stored in these non-translating states. The movement of mRNA into storage and back to translation is dictated by the recognition of the mRNA by trans factors. So, remodeling the factors that bind mRNA is critical for changing the fate of mRNA. RNA helicases, which have the ability to remodel RNA or RNA-protein complexes, are excellent candidates for facilitating such rearrangements. This review will focus on the RNA helicases implicated in translation repression and/or mRNA storage and how their study has illuminated mechanisms of mRNA regulation. This article is part of a Special Issue entitled: The Biology of RNA helicases - Modulation for life.
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Affiliation(s)
- Christopher Hooper
- Department of Neonatology, Vanderbilt Children's Hospital, Nashville, TN, USA
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31
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Stalder L, Heusermann W, Sokol L, Trojer D, Wirz J, Hean J, Fritzsche A, Aeschimann F, Pfanzagl V, Basselet P, Weiler J, Hintersteiner M, Morrissey DV, Meisner-Kober NC. The rough endoplasmatic reticulum is a central nucleation site of siRNA-mediated RNA silencing. EMBO J 2013; 32:1115-27. [PMID: 23511973 PMCID: PMC3630355 DOI: 10.1038/emboj.2013.52] [Citation(s) in RCA: 174] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Accepted: 01/31/2013] [Indexed: 12/24/2022] Open
Abstract
Despite progress in mechanistic understanding of the RNA interference (RNAi) pathways, the subcellular sites of RNA silencing remain under debate. Here we show that loading of lipid-transfected siRNAs and endogenous microRNAs (miRNA) into RISC (RNA-induced silencing complexes), encounter of the target mRNA, and Ago2-mediated mRNA slicing in mammalian cells are nucleated at the rough endoplasmic reticulum (rER). Although the major RNAi pathway proteins are found in most subcellular compartments, the miRNA- and siRNA-loaded Ago2 populations co-sediment almost exclusively with the rER membranes, together with the RISC loading complex (RLC) factors Dicer, TAR RNA binding protein (TRBP) and protein activator of the interferon-induced protein kinase (PACT). Fractionation and membrane co-immune precipitations further confirm that siRNA-loaded Ago2 physically associates with the cytosolic side of the rER membrane. Additionally, RLC-associated double-stranded siRNA, diagnostic of RISC loading, and RISC-mediated mRNA cleavage products exclusively co-sediment with rER. Finally, we identify TRBP and PACT as key factors anchoring RISC to ER membranes in an RNA-independent manner. Together, our findings demonstrate that the outer rER membrane is a central nucleation site of siRNA-mediated RNA silencing.
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Affiliation(s)
- Lukas Stalder
- Novartis Institutes for Biomedical Research, NIBR Biologics Center, RNAi Therapeutics, Basel 4000, Switzerland.
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32
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Eukaryotic mRNA decay: methodologies, pathways, and links to other stages of gene expression. J Mol Biol 2013; 425:3750-75. [PMID: 23467123 DOI: 10.1016/j.jmb.2013.02.029] [Citation(s) in RCA: 111] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 02/24/2013] [Accepted: 02/26/2013] [Indexed: 01/15/2023]
Abstract
mRNA concentration depends on the balance between transcription and degradation rates. On both sides of the equilibrium, synthesis and degradation show, however, interesting differences that have conditioned the evolution of gene regulatory mechanisms. Here, we discuss recent genome-wide methods for determining mRNA half-lives in eukaryotes. We also review pre- and posttranscriptional regulons that coordinate the fate of functionally related mRNAs by using protein- or RNA-based trans factors. Some of these factors can regulate both transcription and decay rates, thereby maintaining proper mRNA homeostasis during eukaryotic cell life.
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33
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The discovery and analysis of P Bodies. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 768:23-43. [PMID: 23224963 DOI: 10.1007/978-1-4614-5107-5_3] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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34
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Mérai Z, Benkovics AH, Nyikó T, Debreczeny M, Hiripi L, Kerényi Z, Kondorosi É, Silhavy D. The late steps of plant nonsense-mediated mRNA decay. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 73:50-62. [PMID: 22974464 DOI: 10.1111/tpj.12015] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Revised: 08/27/2012] [Accepted: 09/03/2012] [Indexed: 05/10/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) is a eukaryotic quality control system that identifies and degrades mRNAs containing premature termination codons (PTCs). If translation terminates at a PTC, the UPF1 NMD factor binds the terminating ribosome and recruits UPF2 and UPF3 to form a functional NMD complex, which triggers the rapid decay of the PTC-containing transcript. Although NMD deficiency is seedling lethal in plants, the mechanism of plant NMD remains poorly understood. To understand how the formation of the NMD complex leads to transcript decay we functionally mapped the UPF1 and SMG7 plant NMD factors, the putative key players of NMD target degradation. Our data indicate that the cysteine-histidine-rich (CH) and helicase domains of UPF1 are only essential for the early steps of NMD, whereas the heavily phosphorylated N- and C-terminal regions play a redundant but essential role in the target transcript degradation steps of NMD. We also show that both the N- and the C-terminal regions of SMG7 are essential for NMD. The N terminus contains a phosphoserine-binding domain that is required for the early steps of NMD, whereas the C terminus is required to trigger the degradation of NMD target transcripts. Moreover, SMG7 is a P-body component that can also remobilize UPF1 from the cytoplasm into processing bodies (P bodies). We propose that the N- and C-terminal phosphorylated regions of UPF1 recruit SMG7 to the functional NMD complex, and then SMG7 transports the PTC-containing transcripts into P bodies for degradation.
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Affiliation(s)
- Zsuzsanna Mérai
- Agricultural Biotechnology Center, Szent-Györgyi 4, H-2100, Gödöllő, Hungary
- Albert-Ludwigs-Universität Freiburg, Institut für Biologie II/Botanik, Schänzlestrasse 1, D-79104, Freiburg, Germany
- Gregor Mendel Institute, Austrian Academy of Sciences, Dr. Bohr-Gasse 3, 1030, Vienna, Austria
| | - Anna H Benkovics
- Agricultural Biotechnology Center, Szent-Györgyi 4, H-2100, Gödöllő, Hungary
- Faculty of Horticultural Science, Corvinus University of Budapest, Villányi 29-43, H-1118, Budapest, Hungary
| | - Tünde Nyikó
- Agricultural Biotechnology Center, Szent-Györgyi 4, H-2100, Gödöllő, Hungary
| | - Mónika Debreczeny
- Institut des Sciences du Végétal, CNRS UPR 2355, 91168, Gif sur Yvette, France
- BRC Institute of Biochemistry, 6726, Szeged, Hungary
| | - László Hiripi
- Agricultural Biotechnology Center, Szent-Györgyi 4, H-2100, Gödöllő, Hungary
| | - Zoltán Kerényi
- Agricultural Biotechnology Center, Szent-Györgyi 4, H-2100, Gödöllő, Hungary
| | - Éva Kondorosi
- Institut des Sciences du Végétal, CNRS UPR 2355, 91168, Gif sur Yvette, France
- BRC Institute of Biochemistry, 6726, Szeged, Hungary
| | - Dániel Silhavy
- Agricultural Biotechnology Center, Szent-Györgyi 4, H-2100, Gödöllő, Hungary
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35
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Abstract
Although most mRNA molecules derived from protein-coding genes are destined to be translated into functional polypeptides, some are eliminated by cellular quality control pathways that collectively perform the task of mRNA surveillance. In the nonsense-mediated decay (NMD) pathway premature translation termination promotes the recruitment of a set of factors that destabilize a targeted mRNA. The same factors also seem to have key roles in repressing the translation of the mRNA, dissociating its terminating ribosome and messenger ribonucleoproteins (mRNPs), promoting the degradation of its truncated polypeptide product and possibly even feeding back to the site of transcription to interfere with splicing of the primary transcript.
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36
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López-Rosas I, Orozco E, Marchat LA, García-Rivera G, Guillen N, Weber C, Carrillo-Tapia E, Hernández de la Cruz O, Pérez-Plasencia C, López-Camarillo C. mRNA decay proteins are targeted to poly(A)+ RNA and dsRNA-containing cytoplasmic foci that resemble P-bodies in Entamoeba histolytica. PLoS One 2012; 7:e45966. [PMID: 23029343 PMCID: PMC3454373 DOI: 10.1371/journal.pone.0045966] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 08/23/2012] [Indexed: 01/30/2023] Open
Abstract
In higher eukaryotes, mRNA degradation and RNA-based gene silencing occur in cytoplasmic foci referred to as processing bodies (P-bodies). In protozoan parasites, the presence of P-bodies and their putative role in mRNA decay have yet to be comprehensively addressed. Identification of P-bodies might provide information on how mRNA degradation machineries evolved in lower eukaryotes. Here, we used immunofluorescence and confocal microscopy assays to investigate the cellular localization of mRNA degradation proteins in the human intestinal parasite Entamoeba histolytica and found evidence of the existence of P-bodies. Two mRNA decay factors, namely the EhXRN2 exoribonuclease and the EhDCP2 decapping enzyme, were localized in cytoplasmic foci in a pattern resembling P-body organization. Given that amoebic foci appear to be smaller and less rounded than those described in higher eukaryotes, we have named them “P-body-like structures”. These foci contain additional mRNA degradation factors, including the EhCAF1 deadenylase and the EhAGO2-2 protein involved in RNA interference. Biochemical analysis revealed that EhCAF1 co-immunoprecipitated with EhXRN2 but not with EhDCP2 or EhAGO2-2, thus linking deadenylation to 5′-to-3′ mRNA decay. The number of EhCAF1-containing foci significantly decreased after inhibition of transcription and translation with actinomycin D and cycloheximide, respectively. Furthermore, results of RNA-FISH assays showed that (i) EhCAF1 colocalized with poly(A)+ RNA and (ii) during silencing of the Ehpc4 gene by RNA interference, EhAGO2-2 colocalized with small interfering RNAs in cytoplasmic foci. Our observation of decapping, deadenylation and RNA interference proteins within P-body-like foci suggests that these structures have been conserved after originating in the early evolution of eukaryotic lineages. To the best of our knowledge, this is the first study to report on the localization of mRNA decay proteins within P-body-like structures in E. histolytica. Our findings should open up opportunities for deciphering the mechanisms of mRNA degradation and RNA-based gene silencing in this deep-branching eukaryote.
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Affiliation(s)
- Itzel López-Rosas
- Programa en Ciencias Genómicas, Universidad Autónoma de la Ciudad de México, México City, México
| | - Esther Orozco
- Programa en Ciencias Genómicas, Universidad Autónoma de la Ciudad de México, México City, México
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados, Instituto Politécnico Nacional, México City, México
| | - Laurence A. Marchat
- Programa Institucional de Biomedicina Molecular y Red en Biotecnología, Escuela Nacional de Medicina y Homeopatía, Instituto Politécnico Nacional, México City, México
| | - Guillermina García-Rivera
- Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados, Instituto Politécnico Nacional, México City, México
| | - Nancy Guillen
- Unité Biologie Cellulaire du Parasitisme, Institut Pasteur, Paris, France
- INSERM U786, Paris, France
| | - Christian Weber
- Unité Biologie Cellulaire du Parasitisme, Institut Pasteur, Paris, France
- INSERM U786, Paris, France
| | - Eduardo Carrillo-Tapia
- Programa en Ciencias Genómicas, Universidad Autónoma de la Ciudad de México, México City, México
| | | | - Carlos Pérez-Plasencia
- Unidad de Genómica y Secuenciación Masiva, Instituto Nacional de Cancerología, México City, México
- Unidad de Biomedicina, Facultad de Estudios Superiores-Iztacala, Universidad Nacional Autónoma de México, México City, México
| | - César López-Camarillo
- Programa en Ciencias Genómicas, Universidad Autónoma de la Ciudad de México, México City, México
- * E-mail:
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Ernoult-Lange M, Baconnais S, Harper M, Minshall N, Souquere S, Boudier T, Bénard M, Andrey P, Pierron G, Kress M, Standart N, le Cam E, Weil D. Multiple binding of repressed mRNAs by the P-body protein Rck/p54. RNA (NEW YORK, N.Y.) 2012; 18:1702-15. [PMID: 22836354 PMCID: PMC3425784 DOI: 10.1261/rna.034314.112] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 06/24/2012] [Indexed: 05/25/2023]
Abstract
Translational repression is achieved by protein complexes that typically bind 3' UTR mRNA motifs and interfere with the formation of the cap-dependent initiation complex, resulting in mRNPs with a closed-loop conformation. We demonstrate here that the human DEAD-box protein Rck/p54, which is a component of such complexes and central to P-body assembly, is in considerable molecular excess with respect to cellular mRNAs and enriched to a concentration of 0.5 mM in P-bodies, where it is organized in clusters. Accordingly, multiple binding of p54 proteins along mRNA molecules was detected in vivo. Consistently, the purified protein bound RNA with no sequence specificity and high nanomolar affinity. Moreover, bound RNA molecules had a relaxed conformation. While RNA binding was ATP independent, relaxing of bound RNA was dependent on ATP, though not on its hydrolysis. We propose that Rck/p54 recruitment by sequence-specific translational repressors leads to further binding of Rck/p54 along mRNA molecules, resulting in their masking, unwinding, and ultimately recruitment to P-bodies. Rck/p54 proteins located at the 5' extremity of mRNA can then recruit the decapping complex, thus coupling translational repression and mRNA degradation.
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Affiliation(s)
| | - Sonia Baconnais
- CNRS UMR 8126, Institut Gustave Roussy, 94800 Villejuif, France
| | | | - Nicola Minshall
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Sylvie Souquere
- CNRS UMR 8122, Institut Gustave Roussy, 94800 Villejuif, France
| | | | - Marianne Bénard
- UPMC Univ Paris 06, CNRS-FRE 3402, 75252 Paris cedex 5, France
| | - Philippe Andrey
- INRA, UMR1318, Institut Jean-Pierre Bourgin, RD10, 78000 Versailles, France
- AgroParisTech, Institut Jean-Pierre Bourgin, RD10, 78000 Versailles, France
| | - Gérard Pierron
- CNRS UMR 8122, Institut Gustave Roussy, 94800 Villejuif, France
| | - Michel Kress
- UPMC Univ Paris 06, CNRS-FRE 3402, 75252 Paris cedex 5, France
| | - Nancy Standart
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, United Kingdom
| | - Eric le Cam
- CNRS UMR 8126, Institut Gustave Roussy, 94800 Villejuif, France
| | - Dominique Weil
- UPMC Univ Paris 06, CNRS-FRE 3402, 75252 Paris cedex 5, France
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38
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Novotny I, Podolská K, Blazíková M, Valásek LS, Svoboda P, Stanek D. Nuclear LSm8 affects number of cytoplasmic processing bodies via controlling cellular distribution of Like-Sm proteins. Mol Biol Cell 2012; 23:3776-85. [PMID: 22875987 PMCID: PMC3459855 DOI: 10.1091/mbc.e12-02-0085] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We show that depletion of nuclear Like-Sm 8 (LSm8) dramatically increases processing body (P-body) number, provide the explanation that LSm8 acts via the alteration of the nuclear–cytoplasmic distribution of LSm2–7 proteins, and propose a model that P-bodies form via self-organization. Processing bodies (P-bodies) are dynamic cytoplasmic structures involved in mRNA degradation, but the mechanism that governs their formation is poorly understood. In this paper, we address a role of Like-Sm (LSm) proteins in formation of P-bodies and provide evidence that depletion of nuclear LSm8 increases the number of P-bodies, while LSm8 overexpression leads to P-body loss. We show that LSm8 knockdown causes relocalization of LSm4 and LSm6 proteins to the cytoplasm and suggest that LSm8 controls nuclear accumulation of all LSm2–7 proteins. We propose a model in which redistribution of LSm2–7 to the cytoplasm creates new binding sites for other P-body components and nucleates new, microscopically visible structures. The model is supported by prolonged residence of two P-body proteins, DDX6 and Ago2, in P-bodies after LSm8 depletion, which indicates stronger interactions between these proteins and P-bodies. Finally, an increased number of P-bodies has negligible effects on microRNA-mediated translation repression and nonsense mediated decay, further supporting the view that the function of proteins localized in P-bodies is independent of visible P-bodies.
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Affiliation(s)
- Ivan Novotny
- Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic
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39
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Abstract
The purpose of this review is to provide an analysis of the latest developments on the functions of the carbon catabolite-repression 4-Not (Ccr4-Not) complex in regulating eukaryotic gene expression. Ccr4-Not is a nine-subunit protein complex that is conserved in sequence and function throughout the eukaryotic kingdom. Although Ccr4-Not has been studied since the 1980s, our understanding of what it does is constantly evolving. Once thought to solely regulate transcription, it is now clear that it has much broader roles in gene regulation, such as in mRNA decay and quality control, RNA export, translational repression and protein ubiquitylation. The mechanism of actions for each of its functions is still being debated. Some of the difficulty in drawing a clear picture is that it has been implicated in so many processes that regulate mRNAs and proteins in both the cytoplasm and the nucleus. We will describe what is known about the Ccr4-Not complex in yeast and other eukaryotes in an effort to synthesize a unified model for how this complex coordinates multiple steps in gene regulation and provide insights into what questions will be most exciting to answer in the future.
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Affiliation(s)
- Jason E. Miller
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, Center for RNA Molecular Biology, Penn State University, University Park, PA 16802
| | - Joseph C. Reese
- Department of Biochemistry and Molecular Biology, Center for Eukaryotic Gene Regulation, Center for RNA Molecular Biology, Penn State University, University Park, PA 16802
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40
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Balagopal V, Fluch L, Nissan T. Ways and means of eukaryotic mRNA decay. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2012; 1819:593-603. [DOI: 10.1016/j.bbagrm.2012.01.001] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2011] [Revised: 12/29/2011] [Accepted: 01/03/2012] [Indexed: 10/14/2022]
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41
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Ghosh S, Jacobson A. RNA decay modulates gene expression and controls its fidelity. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 1:351-61. [PMID: 21132108 DOI: 10.1002/wrna.25] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Maintenance of cellular function relies on the expression of genetic information with high fidelity, a process in which RNA molecules form an important link. mRNAs are intermediates that define the proteome, rRNAs and tRNAs are effector molecules that act together to decode mRNA sequence information, and small noncoding RNAs can regulate mRNA half-life and translatability. The steady-state levels of these RNAs occur through transcriptional and posttranscriptional regulatory mechanisms, of which RNA decay pathways are integral components. RNA decay can initiate from the ends of a transcript or through endonucleolytic cleavage, and numerous factors that catalyze or promote these reactions have been identified and characterized. The rate at which decay occurs depends on RNA sequence or structural elements and usually requires the RNA to be modified in a way that allows recruitment of the decay machinery to the transcript through the binding of accessory factors or small RNAs. The major RNA decay pathways also play important roles in the quality control (QC) of gene expression. Acting in both the nucleus and cytoplasm, multiple QC factors monitor newly synthesized transcripts, or mRNAs undergoing translation, for properties essential to function, including structural integrity or the presence of complete open-reading frames. Transcripts targeted by these surveillance mechanisms are rapidly shunted into conventional decay pathways where they are degraded rapidly to ensure that they do not interfere with the normal course of gene expression. Collectively, degradative mechanisms are important determinants of the extent of gene expression and play key roles in maintaining its accuracy.
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Affiliation(s)
- Shubhendu Ghosh
- Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester, MA 01655-0122, USA
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42
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Jones CI, Zabolotskaya MV, Newbury SF. The 5' → 3' exoribonuclease XRN1/Pacman and its functions in cellular processes and development. WILEY INTERDISCIPLINARY REVIEWS-RNA 2012; 3:455-68. [PMID: 22383165 DOI: 10.1002/wrna.1109] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
XRN1 is a 5' → 3' processive exoribonuclease that degrades mRNAs after they have been decapped. It is highly conserved in all eukaryotes, including homologs in Drosophila melanogaster (Pacman), Caenorhabditis elegans (XRN1), and Saccharomyces cerevisiae (Xrn1p). As well as being a key enzyme in RNA turnover, XRN1 is involved in nonsense-mediated mRNA decay and degradation of mRNAs after they have been targeted by small interfering RNAs or microRNAs. The crystal structure of XRN1 can explain its processivity and also the selectivity of the enzyme for 5' monophosphorylated RNA. In eukaryotic cells, XRN1 is often found in particles known as processing bodies (P bodies) together with other proteins involved in the 5' → 3' degradation pathway, such as DCP2 and the helicase DHH1 (Me31B). Although XRN1 shows little specificity to particular 5' monophosphorylated RNAs in vitro, mutations in XRN1 in vivo have specific phenotypes suggesting that it specifically degrades a subset of RNAs. In Drosophila, mutations in the gene encoding the XRN1 homolog pacman result in defects in wound healing, epithelial closure and stem cell renewal in testes. We propose a model where specific mRNAs are targeted to XRN1 via specific binding of miRNAs and/or RNA-binding proteins to instability elements within the RNA. These guide the RNA to the 5' core degradation apparatus for controlled degradation.
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Abstract
Cytoplasmic mRNA protein complexes (mRNPs) can assemble in granules, such as processing bodies (P-bodies) and stress granules (SGs). Both P-bodies and SGs contain repressed messenger RNAs (mRNAs) and proteins that regulate the fate of the mRNA. P-bodies contain factors involved in translation repression and mRNA decay; SGs contain a subset of translation initiation factors and mRNA-binding proteins. mRNAs cycle in and out of granules and can return to translation. RNA helicases are found in both P-bodies and SGs. These enzymes are prime candidates for facilitating the changes in mRNP structure and composition that may determine whether an mRNA is translated, stored, or degraded. This chapter focuses on the RNA helicases that localize to cytoplasmic granules. I outline approaches to define how the helicases affect the granules and the mRNAs within them, and I explain how analysis of cytoplasmic granules provides insight into physiological function and targets of RNA helicases.
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Affiliation(s)
- Angela Hilliker
- Department of Biology, The University of Richmond, Richmond, Virginia, USA
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Yepiskoposyan H, Aeschimann F, Nilsson D, Okoniewski M, Mühlemann O. Autoregulation of the nonsense-mediated mRNA decay pathway in human cells. RNA (NEW YORK, N.Y.) 2011; 17:2108-18. [PMID: 22028362 PMCID: PMC3222124 DOI: 10.1261/rna.030247.111] [Citation(s) in RCA: 194] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) is traditionally portrayed as a quality-control mechanism that degrades mRNAs with truncated open reading frames (ORFs). However, it is meanwhile clear that NMD also contributes to the post-transcriptional gene regulation of numerous physiological mRNAs. To identify endogenous NMD substrate mRNAs and analyze the features that render them sensitive to NMD, we performed transcriptome profiling of human cells depleted of the NMD factors UPF1, SMG6, or SMG7. It revealed that mRNAs up-regulated by NMD abrogation had a greater median 3'-UTR length compared with that of the human mRNAome and were also enriched for 3'-UTR introns and uORFs. Intriguingly, most mRNAs coding for NMD factors were among the NMD-sensitive transcripts, implying that the NMD process is autoregulated. These mRNAs all possess long 3' UTRs, and some of them harbor uORFs. Using reporter gene assays, we demonstrated that the long 3' UTRs of UPF1, SMG5, and SMG7 mRNAs are the main NMD-inducing features of these mRNAs, suggesting that long 3' UTRs might be a frequent trigger of NMD.
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Affiliation(s)
- Hasmik Yepiskoposyan
- Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
| | - Florian Aeschimann
- Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
| | - Daniel Nilsson
- Science for Life Laboratory, Clinical Genetics Unit L5:03, Karolinska University Hospital, Solna 171 76, Stockholm, Sweden
| | - Michal Okoniewski
- Functional Genomics Center, University of Zurich and Swiss Federal Institute of Technology, 8057 Zurich, Switzerland
| | - Oliver Mühlemann
- Department of Chemistry and Biochemistry, University of Bern, 3012 Bern, Switzerland
- Corresponding author.E-mail .
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Giménez-Barcons M, Díez J. Yeast processing bodies and stress granules: self-assembly ribonucleoprotein particles. Microb Cell Fact 2011; 10:73. [PMID: 21943185 PMCID: PMC3191479 DOI: 10.1186/1475-2859-10-73] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 09/24/2011] [Indexed: 11/23/2022] Open
Abstract
Processing bodies (PBs) and stress granules (SGs) are two highly conserved cytoplasmic ribonucleoprotein foci that contain translationally repressed mRNAs together with proteins from the mRNA metabolism. Interestingly, they also share some common features with other granules, including the prokaryotic inclusion bodies. Although the function of PBs and SGs remains elusive, major advances have been done in unraveling their composition and assembly by using the yeast Saccharomyces cerevisae.
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Affiliation(s)
- Mireia Giménez-Barcons
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, 08003 Barcelona, Spain
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Choe J, Cho H, Chi SG, Kim YK. Ago2/miRISC-mediated inhibition of CBP80/20-dependent translation and thereby abrogation of nonsense-mediated mRNA decay require the cap-associating activity of Ago2. FEBS Lett 2011; 585:2682-7. [DOI: 10.1016/j.febslet.2011.07.047] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2011] [Revised: 07/19/2011] [Accepted: 07/28/2011] [Indexed: 02/04/2023]
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Affiliation(s)
- Stacy L Erickson
- Division of Biology, University of California San Diego, La Jolla, CA 92093, USA
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Huang L, Mollet S, Souquere S, Le Roy F, Ernoult-Lange M, Pierron G, Dautry F, Weil D. Mitochondria associate with P-bodies and modulate microRNA-mediated RNA interference. J Biol Chem 2011; 286:24219-30. [PMID: 21576251 DOI: 10.1074/jbc.m111.240259] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
P-bodies are cytoplasmic granules that are linked to mRNA decay, mRNA storage, and RNA interference (RNAi). They are known to interact with stress granules in stressed cells, and with late endosomes. Here, we report that P-bodies also interact with mitochondria, as previously described for P-body-related granules in germ cells. The interaction is dynamic, as a large majority of P-bodies contacts mitochondria at least once within a 3-min interval, and for about 18 s. This association requires an intact microtubule network. The depletion of P-bodies does not seem to affect mitochondria, nor the mitochondrial activity to be required for their contacts with P-bodies. However, inactivation of mitochondria leads to a strong decrease of miRNA-mediated RNAi efficiency, and to a lesser extent of siRNA-mediated RNAi. The defect occurs during the assembly of active RISC and is associated with a specific delocalization of endogeneous Ago2 from P-bodies. Our study reveals the possible involvement of RNAi defect in pathologies involving mitochondrial deficiencies.
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Affiliation(s)
- Lue Huang
- LBPA, CNRS, Ecole Normale Supérieure de Cachan, 94230 Cachan, France
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Li Y, Song M, Kiledjian M. Differential utilization of decapping enzymes in mammalian mRNA decay pathways. RNA (NEW YORK, N.Y.) 2011; 17:419-428. [PMID: 21224379 PMCID: PMC3039142 DOI: 10.1261/rna.2439811] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 12/09/2010] [Indexed: 05/30/2023]
Abstract
mRNA decapping is a crucial step in the regulation of mRNA stability and gene expression. Dcp2 is an mRNA decapping enzyme that has been widely studied. We recently reported the presence of a second mammalian cytoplasmic decapping enzyme, Nudt16. Here we address the differential utilization of the two decapping enzymes in specified mRNA decay processes. Using mouse embryonic fibroblast (MEF) cell lines derived from a hypomorphic knockout of the Dcp2 gene with undetectable levels of Dcp2 or MEF cell lines harboring a Nudt16-directed shRNA to generate reduced levels of Nudt16, we demonstrate the distinct roles for Dcp2 and Nudt16 in nonsense-mediated mRNA decay (NMD), decay of ARE-containing mRNA and miRNA-mediated silencing. Our results indicated that NMD preferentially utilizes Dcp2 rather than Nudt16; Dcp2 and Nudt16 are redundant in miRNA-mediated silencing; and Dcp2 and Nudt16 are differentially utilized for ARE-mRNA decay. These data demonstrate that the two distinct decapping enzymes can uniquely function in specific mRNA decay processes in mammalian cells.
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Affiliation(s)
- You Li
- Department of Cell Biology and Neuroscience, Rutgers University, Piscataway, New Jersey 08854-8082, USA
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Benkovics AH, Nyikó T, Mérai Z, Silhavy D, Bisztray GD. Functional analysis of the grapevine paralogs of the SMG7 NMD factor using a heterolog VIGS-based gene depletion-complementation system. PLANT MOLECULAR BIOLOGY 2011; 75:277-90. [PMID: 21234790 DOI: 10.1007/s11103-010-9726-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Accepted: 12/24/2010] [Indexed: 05/23/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) is a eukaryotic quality control system that identifies and eliminates transcripts having a premature translation termination codon (PTC). NMD is also involved in the control of several wild-type mRNAs. The NMD core machinery consists of three highly conserved NMD factors (UPF1, UPF2 and UPF3) and at least one less conserved 14-3-3-like domain containing protein (SMG7). A PTC is identified by UPF factors, and then SMG7 triggers rapid transcript decay. UPF factors are generally encoded by a single gene, whereas SMG7 has duplicated several times during evolution. Recently it was reported that the plant SMG7 is autoregulated through NMD and that SMG7 has two relatively divergent paralogs in dicots, SMG7 and SMG7L. In mammals all three SMG7 related genes (SMG5, SMG6 and SMG7) are essential in NMD, so we hypothesized that in plants the SMG7 and SMG7L duplicates may also play distinct roles in NMD. To test this possibility, we have analyzed the evolution and the function of plant SMG7 homologs. We show that SMG7L is not required for plant NMD. Interestingly, we found that the grapevine and poplar genomes contain two quite divergent SMG7 paralogs which may have derived from an ancient duplication event. Using heterolog depletion/complementation assays we demonstrate that both grapevine SMG7 copies retained the complete NMD activity and both of them are under NMD control, whilst SMG7L has lost NMD activity and NMD control.
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