1
|
May JP, Simon AE. Targeting of viral RNAs by Upf1-mediated RNA decay pathways. Curr Opin Virol 2020; 47:1-8. [PMID: 33341474 DOI: 10.1016/j.coviro.2020.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 11/10/2020] [Accepted: 11/12/2020] [Indexed: 12/25/2022]
Abstract
Viral RNAs are susceptible to co-translational RNA decay pathways mediated by the RNA helicase Upstream frameshift 1 (Upf1). Upf1 is a key component in nonsense-mediated decay (NMD), Staufen1-mediated mRNA decay (SMD), and structure-mediated RNA decay (SRD) pathways, among others. Diverse families of viruses have features that predispose them to Upf1 targeting, but have evolved means to escape decay through the action of cis-acting or trans-acting viral factors. Studies aimed at understanding how viruses are subjected to and circumvent NMD have increased our understanding of NMD target selection of host mRNAs. This review focuses on the knowledge gained from studying NMD in viral systems as well as related Upf1-dependent pathways and how these pathways restrict virus replication.
Collapse
Affiliation(s)
- Jared P May
- Department of Cell and Molecular Biology and Biochemistry, School of Biological and Chemical Sciences, University of Missouri-Kansas City, Kansas City, MO 64110, USA.
| | - Anne E Simon
- Department of Cell Biology and Molecular Genetics, University of Maryland - College Park, College Park, MD, USA.
| |
Collapse
|
2
|
Pervasive changes of mRNA splicing in upf1-deficient zebrafish identify rpl10a as a regulator of T cell development. Proc Natl Acad Sci U S A 2020; 117:15799-15808. [PMID: 32571908 PMCID: PMC7354994 DOI: 10.1073/pnas.1917812117] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The transcriptome of eukaryotic cells is constantly monitored for errors to avoid the production of undesired protein variants. The evolutionarily conserved nonsense-mediated mRNA decay (NMD) pathway degrades aberrant mRNAs, but also functions in the regulation of transcript abundance in response to changed physiological states. Here, we describe a zebrafish mutant of upf1, encoding the central component of the NMD machinery. Fish homozygous for the upf1 t20450 allele (Y163X) survive until day 10 after fertilization, presenting with impaired T cell development as one of the most conspicuous features of the mutant phenotype. Analysis of differentially expressed genes identified dysregulation of the pre-mRNA splicing pathway, accompanied by perturbed autoregulation of canonical splicing activators (SRSF) and repressors (HNRNP). In upf1-deficient mutants, NMD-susceptible transcripts of ribosomal proteins that are known for their role as noncanonical splicing regulators were greatly increased, most notably, rpl10a When the levels of NMD-susceptible rpl10a transcripts were artificially increased in zebrafish larvae, T cell development was significantly impaired, suggesting that perturbed autoregulation of rpl10a splicing contributes to failing T cell development in upf1 deficiency. Our results identify an extraribosomal tissue-specific function to rpl10a in the immune system, and thus exemplify the advantages of the zebrafish model to study the effects of upf1-deficiency in the context of a vertebrate organism.
Collapse
|
3
|
Wang X, Shan X, Gregory-Evans K, Gregory-Evans CY. RNA-based therapies in animal models of Leber congenital amaurosis causing blindness. PRECISION CLINICAL MEDICINE 2020; 3:113-126. [PMID: 35692607 PMCID: PMC8985810 DOI: 10.1093/pcmedi/pbaa009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 03/05/2020] [Accepted: 03/10/2020] [Indexed: 11/14/2022] Open
Abstract
Abstract
Leber congenital amaurosis (LCA) is a severe, genetically heterogeneous recessive eye disease in which ~ 35% of gene mutations are in-frame nonsense mutations coding for loss-of-function premature termination codons (PTCs) in mRNA. Nonsense suppression therapy allows read-through of PTCs leading to production of full-length protein. A limitation of nonsense suppression is that nonsense-mediated decay (NMD) degrades PTC-containing RNA transcripts. The purpose of this study was to determine whether inhibition of NMD could improve nonsense suppression efficacy in vivo. Using a high-throughput approach in the recessive cep290 zebrafish model of LCA (cep290;Q1223X), we first tested the NMD inhibitor Amlexanox in combination with the nonsense suppression drug Ataluren. We observed reduced retinal cell death and improved visual function. With these positive data, we next investigated whether this strategy was also applicable across species in two mammalian models: Rd12 (rpe65;R44X) and Rd3 (rd3;R107X) mouse models of LCA. In the Rd12 model, cell death was reduced, RPE65 protein was produced, and in vivo visual function testing was improved. We establish for the first time that the mechanism of action of Amlexanox in Rd12 retina was through reduced UPF1 phosphorylation. In the Rd3 model, however, no beneficial effect was observed with Ataluren alone or in combination with Amlexanox. This variation in response establishes that some forms of nonsense mutation LCA can be targeted by RNA therapies, but that this needs to be verified for each genotype. The implementation of precision medicine by identifying better responders to specific drugs is essential for development of validated retinal therapies.
Collapse
Affiliation(s)
- Xia Wang
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver BC V5Z 3N9, Canada
| | - Xianghong Shan
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver BC V5Z 3N9, Canada
| | - Kevin Gregory-Evans
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver BC V5Z 3N9, Canada
| | - Cheryl Y Gregory-Evans
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver BC V5Z 3N9, Canada
| |
Collapse
|
4
|
Hong D, Park T, Jeong S. Nuclear UPF1 Is Associated with Chromatin for Transcription-Coupled RNA Surveillance. Mol Cells 2019; 42:523-529. [PMID: 31234619 PMCID: PMC6681869 DOI: 10.14348/molcells.2019.0116] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 06/19/2019] [Accepted: 06/19/2019] [Indexed: 01/26/2023] Open
Abstract
mRNA quality is controlled by multiple RNA surveillance machineries to reduce errors during gene expression processes in eukaryotic cells. Nonsense-mediated mRNA decay (NMD) is a well-characterized mechanism that degrades error-containing transcripts during translation. The ATP-dependent RNA helicase up-frameshift 1 (UPF1) is a key player in NMD that is mostly prevalent in the cytoplasm. However, recent studies on UPF1-RNA interaction suggest more comprehensive roles of UPF1 on diverse forms of target transcripts. Here we used subcellular fractionation and immunofluorescence to understand such complex functions of UPF1. We demonstrated that UPF1 can be localized to the nucleus and predominantly associated with the chromatin. Moreover, we showed that UPF1 associates more strongly with the chromatin when the transcription elongation and translation inhibitors were used. These findings suggest a novel role of UPF1 in transcription elongation-coupled RNA machinery in the chromatin, as well as in translation-coupled NMD in the cytoplasm. Thus, we propose that cytoplasmic UPF1-centric RNA surveillance mechanism could be extended further up to the chromatin-associated UPF1 and cotranscriptional RNA surveillance. Our findings could provide the mechanistic insights on extensive regulatory roles of UPF1 for many cellular RNAs.
Collapse
Affiliation(s)
- Dawon Hong
- Graduate Department of Bioconvergence Science and Technology, Dankook University, Yongin 16892,
Korea
| | - Taeyoung Park
- Graduate Department of Bioconvergence Science and Technology, Dankook University, Yongin 16892,
Korea
| | - Sunjoo Jeong
- Graduate Department of Bioconvergence Science and Technology, Dankook University, Yongin 16892,
Korea
| |
Collapse
|
5
|
Kim YK, Maquat LE. UPFront and center in RNA decay: UPF1 in nonsense-mediated mRNA decay and beyond. RNA (NEW YORK, N.Y.) 2019; 25:407-422. [PMID: 30655309 PMCID: PMC6426291 DOI: 10.1261/rna.070136.118] [Citation(s) in RCA: 133] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Nonsense-mediated mRNA decay (NMD), which is arguably the best-characterized translation-dependent regulatory pathway in mammals, selectively degrades mRNAs as a means of post-transcriptional gene control. Control can be for the purpose of ensuring the quality of gene expression. Alternatively, control can facilitate the adaptation of cells to changes in their environment. The key to NMD, no matter what its purpose, is the ATP-dependent RNA helicase upstream frameshift 1 (UPF1), without which NMD fails to occur. However, UPF1 does much more than regulate NMD. As examples, UPF1 is engaged in functionally diverse mRNA decay pathways mediated by a variety of RNA-binding proteins that include staufen, stem-loop-binding protein, glucocorticoid receptor, and regnase 1. Moreover, UPF1 promotes tudor-staphylococcal/micrococcal-like nuclease-mediated microRNA decay. In this review, we first focus on how the NMD machinery recognizes an NMD target and triggers mRNA degradation. Next, we compare and contrast the mechanisms by which UPF1 functions in the decay of other mRNAs and also in microRNA decay. UPF1, as a protein polymath, engenders cells with the ability to shape their transcriptome in response to diverse biological and physiological needs.
Collapse
Affiliation(s)
- Yoon Ki Kim
- Creative Research Initiatives Center for Molecular Biology of Translation, Korea University, Seoul 02841, Republic of Korea
- Division of Life Sciences, Korea University, Seoul 02841, Republic of Korea
| | - Lynne E Maquat
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
- Center for RNA Biology, University of Rochester, Rochester, New York 14642, USA
| |
Collapse
|
6
|
Moon BS, Bai J, Cai M, Liu C, Shi J, Lu W. Kruppel-like factor 4-dependent Staufen1-mediated mRNA decay regulates cortical neurogenesis. Nat Commun 2018; 9:401. [PMID: 29374155 PMCID: PMC5785957 DOI: 10.1038/s41467-017-02720-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Accepted: 12/18/2017] [Indexed: 11/10/2022] Open
Abstract
Kruppel-like factor 4 (Klf4) is a zinc-finger-containing protein that plays a critical role in diverse cellular physiology. While most of these functions attribute to its role as a transcription factor, it is postulated that Klf4 may play a role other than transcriptional regulation. Here we demonstrate that Klf4 loss in neural progenitor cells (NPCs) leads to increased neurogenesis and reduced self-renewal in mice. In addition, Klf4 interacts with RNA-binding protein Staufen1 (Stau1) and RNA helicase Ddx5/17. They function together as a complex to maintain NPC self-renewal. We report that Klf4 promotes Stau1 recruitment to the 3'-untranslated region of neurogenesis-associated mRNAs, increasing Stau1-mediated mRNA decay (SMD) of these transcripts. Stau1 depletion abrogated SMD of target mRNAs and rescued neurogenesis defects in Klf4-overexpressing NPCs. Furthermore, Ddx5/17 knockdown significantly blocked Klf4-mediated mRNA degradation. Our results highlight a novel molecular mechanism underlying stability of neurogenesis-associated mRNAs controlled by the Klf4/Ddx5/17/Stau1 axis during mammalian corticogenesis.
Collapse
Affiliation(s)
- Byoung-San Moon
- Department of Stem Cell Biology and Regenerative Medicine, Broad Center for Regenerative Medicine and Stem Cell Research, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA.,State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, 94 Weijin Road, 300071, Tianjin, China
| | - Jinlun Bai
- Department of Stem Cell Biology and Regenerative Medicine, Broad Center for Regenerative Medicine and Stem Cell Research, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA
| | - Mingyang Cai
- Department of Stem Cell Biology and Regenerative Medicine, Broad Center for Regenerative Medicine and Stem Cell Research, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA
| | - Chunming Liu
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, 40506, USA
| | - Jiandang Shi
- State Key Laboratory of Medicinal Chemical Biology and College of Life Sciences, Nankai University, 94 Weijin Road, 300071, Tianjin, China
| | - Wange Lu
- Department of Stem Cell Biology and Regenerative Medicine, Broad Center for Regenerative Medicine and Stem Cell Research, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90033, USA.
| |
Collapse
|
7
|
González-Huici V, Wang B, Gartner A. A Role for the Nonsense-Mediated mRNA Decay Pathway in Maintaining Genome Stability in Caenorhabditis elegans. Genetics 2017; 206:1853-1864. [PMID: 28634159 PMCID: PMC5560793 DOI: 10.1534/genetics.117.203414] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 06/05/2017] [Indexed: 12/31/2022] Open
Abstract
Ionizing radiation (IR) is commonly used in cancer therapy and is a main source of DNA double-strand breaks (DSBs), one of the most toxic forms of DNA damage. We have used Caenorhabditis elegans as an invertebrate model to identify novel factors required for repair of DNA damage inflicted by IR. We have performed an unbiased genetic screen, finding that smg-1 mutations confer strong hyper-sensitivity to IR. SMG-1 is a phosphoinositide-3 kinase (PI3K) involved in mediating nonsense-mediated mRNA decay (NMD) of transcripts containing premature stop codons and related to the ATM and ATR kinases which are at the apex of DNA damage signaling pathways. Hyper-sensitivity to IR also occurs when other genes mediating NMD are mutated. The hyper-sensitivity to bleomycin, a drug known to induce DSBs, further supports that NMD pathway mutants are defective in DSB repair. Hyper-sensitivity was not observed upon treatment with alkylating agents or UV irradiation. We show that SMG-1 mainly acts in mitotically dividing germ cells, and during late embryonic and larval development. Based on epistasis experiments, SMG-1 does not appear to act in any of the three major pathways known to mend DNA DSBs, namely homologous recombination (HR), nonhomologous end-joining (NHEJ), and microhomology-mediated end-joining (MMEJ). We speculate that SMG-1 kinase activity could be activated following DNA damage to phosphorylate specific DNA repair proteins and/or that NMD inactivation may lead to aberrant mRNAs leading to synthesis of malfunctioning DNA repair proteins.
Collapse
Affiliation(s)
- Víctor González-Huici
- School of Life Sciences, Centre for Gene Regulation and Expression, University of Dundee, DD1 5EH, UK
| | - Bin Wang
- School of Life Sciences, Centre for Gene Regulation and Expression, University of Dundee, DD1 5EH, UK
| | - Anton Gartner
- School of Life Sciences, Centre for Gene Regulation and Expression, University of Dundee, DD1 5EH, UK
| |
Collapse
|
8
|
DNA Replication Origins and Fork Progression at Mammalian Telomeres. Genes (Basel) 2017; 8:genes8040112. [PMID: 28350373 PMCID: PMC5406859 DOI: 10.3390/genes8040112] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Revised: 03/23/2017] [Accepted: 03/24/2017] [Indexed: 12/20/2022] Open
Abstract
Telomeres are essential chromosomal regions that prevent critical shortening of linear chromosomes and genomic instability in eukaryotic cells. The bulk of telomeric DNA is replicated by semi-conservative DNA replication in the same way as the rest of the genome. However, recent findings revealed that replication of telomeric repeats is a potential cause of chromosomal instability, because DNA replication through telomeres is challenged by the repetitive telomeric sequences and specific structures that hamper the replication fork. In this review, we summarize current understanding of the mechanisms by which telomeres are faithfully and safely replicated in mammalian cells. Various telomere-associated proteins ensure efficient telomere replication at different steps, such as licensing of replication origins, passage of replication forks, proper fork restart after replication stress, and dissolution of post-replicative structures. In particular, shelterin proteins have central roles in the control of telomere replication. Through physical interactions, accessory proteins are recruited to maintain telomere integrity during DNA replication. Dormant replication origins and/or homology-directed repair may rescue inappropriate fork stalling or collapse that can cause defects in telomere structure and functions.
Collapse
|
9
|
Li Z, Vuong JK, Zhang M, Stork C, Zheng S. Inhibition of nonsense-mediated RNA decay by ER stress. RNA (NEW YORK, N.Y.) 2017; 23:378-394. [PMID: 27940503 PMCID: PMC5311500 DOI: 10.1261/rna.058040.116] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2016] [Accepted: 12/06/2016] [Indexed: 05/26/2023]
Abstract
Nonsense-mediated RNA decay (NMD) selectively degrades mutated and aberrantly processed transcripts that contain premature termination codons (PTC). Cellular NMD activity is typically assessed using exogenous PTC-containing reporters. We overcame some inherently problematic aspects of assaying endogenous targets and developed a broadly applicable strategy to reliably and easily monitor changes in cellular NMD activity. Our new method was genetically validated for distinguishing NMD regulation from transcriptional control and alternative splicing regulation, and unexpectedly disclosed a different sensitivity of NMD targets to NMD inhibition. Applying this robust method for screening, we identified NMD-inhibiting stressors but also found that NMD inactivation was not universal to cellular stresses. The high sensitivity and broad dynamic range of our method revealed a strong correlation between NMD inhibition, endoplasmic reticulum (ER) stress, and polysome disassembly upon thapsigargin treatment in a temporal and dose-dependent manner. We found little evidence of calcium signaling mediating thapsigargin-induced NMD inhibition. Instead, we discovered that of the three unfolded protein response (UPR) pathways activated by thapsigargin, mainly protein kinase RNA-like endoplasmic reticulum kinase (PERK) was required for NMD inhibition. Finally, we showed that ER stress compounded TDP-43 depletion in the up-regulation of NMD isoforms that had been implicated in the pathogenic mechanisms of amyotrophic lateral sclerosis and frontotemporal dementia, and that the additive effect of ER stress was completely blocked by PERK deficiency.
Collapse
Affiliation(s)
- Zhelin Li
- Division of Biomedical Sciences, University of California, Riverside, California 92521, USA
| | - John K Vuong
- Division of Biomedical Sciences, University of California, Riverside, California 92521, USA
| | - Min Zhang
- Division of Biomedical Sciences, University of California, Riverside, California 92521, USA
| | - Cheryl Stork
- Division of Biomedical Sciences, University of California, Riverside, California 92521, USA
| | - Sika Zheng
- Division of Biomedical Sciences, University of California, Riverside, California 92521, USA
| |
Collapse
|
10
|
Efficient large-scale preparation and purification of short single-stranded RNA oligonucleotides. Biotechniques 2016; 60:75-83. [PMID: 26842352 DOI: 10.2144/000114383] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 12/12/2015] [Indexed: 11/23/2022] Open
Abstract
Sequence-specific RNA recognition by RNA-binding proteins plays a crucial role in the post-translational regulation of gene expression. Biophysical and biochemical studies help to unravel the principles of sequence-specific RNA recognition, but the methods used require large amounts of single-stranded RNA (ssRNA). Here we present a fast and robust method for large-scale preparation and purification of short ssRNA oligonucleotides for biochemical, biophysical, and structural studies. We designed an efficiently folding, self-cleaving hammerhead (HH) ribozyme to prepare ssRNA oligonucleotides. Hammerhead ribozyme RNAs self-cleave with over 95% efficiency during in vitro transcription as a function of magnesium concentration to produce high yields of the desired ssRNA products. The resulting ssRNAs can be purified from crude transcription reactions by denaturing anion-exchange chromatography and then desalted by weak anion-exchange chromatography using volatile ammonium bicarbonate buffer solutions. The ssRNA oligonucleotides produced this way are homogenous, as judged by mass spectrometry (MS), and are suitable for biochemical and biophysical studies. Moreover, for high-resolution NMR structure determination of RNA-protein complexes, our protocol enables efficient preparation of ssRNA oligonucleotides with various isotope-labeling schemes which are not commercially available.
Collapse
|
11
|
Ajamian L, Abel K, Rao S, Vyboh K, García-de-Gracia F, Soto-Rifo R, Kulozik AE, Gehring NH, Mouland AJ. HIV-1 Recruits UPF1 but Excludes UPF2 to Promote Nucleocytoplasmic Export of the Genomic RNA. Biomolecules 2015; 5:2808-39. [PMID: 26492277 PMCID: PMC4693258 DOI: 10.3390/biom5042808] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2015] [Revised: 09/09/2015] [Accepted: 09/16/2015] [Indexed: 12/11/2022] Open
Abstract
Unspliced, genomic HIV-1 RNA (vRNA) is a component of several ribonucleoprotein complexes (RNP) during the viral replication cycle. In earlier work, we demonstrated that the host upframeshift protein 1 (UPF1), a key factor in nonsense-mediated mRNA decay (NMD), colocalized and associated to the viral structural protein Gag during viral egress. In this work, we demonstrate a new function for UPF1 in the regulation of vRNA nuclear export. OPEN ACCESS Biomolecules 2015, 5 2809 We establish that the nucleocytoplasmic shuttling of UPF1 is required for this function and demonstrate that UPF1 exists in two essential viral RNPs during the late phase of HIV-1 replication: the first, in a nuclear export RNP that contains Rev, CRM1, DDX3 and the nucleoporin p62, and the second, which excludes these nuclear export markers but contains Gag in the cytoplasm. Interestingly, we observed that both UPF2 and the long isoform of UPF3a, UPF3aL, but not the shorter isoforms UPF3aS and UPF3b, are excluded from the UPF1-Rev-CRM1-DDX3 complex as they are negative regulators of vRNA nuclear export. In silico protein-protein docking analyses suggest that Rev binds UPF1 in a region that overlaps the UPF2 binding site, thus explaining the exclusion of this negative regulatory factor by HIV-1 that is necessary for vRNA trafficking. This work uncovers a novel and unique regulatory circuit involving several UPF proteins that ultimately regulate vRNA nuclear export and trafficking.
Collapse
Affiliation(s)
- Lara Ajamian
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, Montréal QC H3T 1E2, Canada.
- Department of Medicine, Division of Experimental Medicine, McGill University, Montréal QC H3A 2B4, Canada.
| | - Karen Abel
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, Montréal QC H3T 1E2, Canada.
- Department of Microbiology and Immunology, McGill University, Montréal QC H3T 1E2, Canada.
| | - Shringar Rao
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, Montréal QC H3T 1E2, Canada.
- Department of Microbiology and Immunology, McGill University, Montréal QC H3T 1E2, Canada.
| | - Kishanda Vyboh
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, Montréal QC H3T 1E2, Canada.
- Department of Microbiology and Immunology, McGill University, Montréal QC H3T 1E2, Canada.
| | - Francisco García-de-Gracia
- Laboratory of Molecular and Cellular Virology, Virology Program, Biomedical Sciences Institute, Faculty of Medicine, Universidad de Chile, Independencia 8389100, Santiago, Chile.
| | - Ricardo Soto-Rifo
- Laboratory of Molecular and Cellular Virology, Virology Program, Biomedical Sciences Institute, Faculty of Medicine, Universidad de Chile, Independencia 8389100, Santiago, Chile.
| | - Andreas E Kulozik
- Department of Pediatric Oncology, Hematology and Immunology, Heidelberg 69120, Germany.
- European Molecular Biology Laboratory, Partnership Unit, University of Heidelberg Molecular Medicine, Heidelberg 69117, Germany.
| | - Niels H Gehring
- Institute for Genetics, University of Cologne, Cologne 50674, Germany.
| | - Andrew J Mouland
- HIV-1 RNA Trafficking Laboratory, Lady Davis Institute for Medical Research-Sir Mortimer B. Davis Jewish General Hospital, Montréal QC H3T 1E2, Canada.
- Department of Medicine, Division of Experimental Medicine, McGill University, Montréal QC H3A 2B4, Canada.
- Department of Microbiology and Immunology, McGill University, Montréal QC H3T 1E2, Canada.
| |
Collapse
|
12
|
Abstract
Alu element is the most successful transposon and it maintains a high level of content in primate genome. However, despite the fact that the expression level of independent Alu element is rather low under common condition, an increasing number of the observations for the Alu transcripts in cells and tissues have been reported recently. Alu transcripts play key roles in the network of gene expression regulation. The main functions of Alu transcript focus on gene regulation both at transcriptional and post-transcriptional levels. This review summarizes major functions of Alu transcripts on gene expression and highlights molecular mechanisms dependent on conserved sequence or secondary structure in order to unravel a relative ubiquitous way that Alu transcript uses to affect the whole genome.
Collapse
Affiliation(s)
- Li Zhang
- Laboratory of Fully Human Antibody Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China.
| | - Ju-Gao Chen
- Department of Oncology, The Second Clinical Medical college (Shenzhen People׳s Hospital), Jinan University, Shenzhen, Guangdong, China
| | - Qi Zhao
- Laboratory of Fully Human Antibody Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong, China.
| |
Collapse
|
13
|
De la Fuente IM. Elements of the cellular metabolic structure. Front Mol Biosci 2015; 2:16. [PMID: 25988183 PMCID: PMC4428431 DOI: 10.3389/fmolb.2015.00016] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 04/12/2015] [Indexed: 12/19/2022] Open
Abstract
A large number of studies have demonstrated the existence of metabolic covalent modifications in different molecular structures, which are able to store biochemical information that is not encoded by DNA. Some of these covalent mark patterns can be transmitted across generations (epigenetic changes). Recently, the emergence of Hopfield-like attractor dynamics has been observed in self-organized enzymatic networks, which have the capacity to store functional catalytic patterns that can be correctly recovered by specific input stimuli. Hopfield-like metabolic dynamics are stable and can be maintained as a long-term biochemical memory. In addition, specific molecular information can be transferred from the functional dynamics of the metabolic networks to the enzymatic activity involved in covalent post-translational modulation, so that determined functional memory can be embedded in multiple stable molecular marks. The metabolic dynamics governed by Hopfield-type attractors (functional processes), as well as the enzymatic covalent modifications of specific molecules (structural dynamic processes) seem to represent the two stages of the dynamical memory of cellular metabolism (metabolic memory). Epigenetic processes appear to be the structural manifestation of this cellular metabolic memory. Here, a new framework for molecular information storage in the cell is presented, which is characterized by two functionally and molecularly interrelated systems: a dynamic, flexible and adaptive system (metabolic memory) and an essentially conservative system (genetic memory). The molecular information of both systems seems to coordinate the physiological development of the whole cell.
Collapse
Affiliation(s)
- Ildefonso M. De la Fuente
- Department of Cell Biology and Immunology, Institute of Parasitology and Biomedicine “López-Neyra,” Consejo Superior de Investigaciones CientíficasGranada, Spain
- Department of Mathematics, University of the Basque Country, UPV/Euskal Herriko UnibertsitateaLeioa, Spain
| |
Collapse
|
14
|
Maekawa S, Imamachi N, Irie T, Tani H, Matsumoto K, Mizutani R, Imamura K, Kakeda M, Yada T, Sugano S, Suzuki Y, Akimitsu N. Analysis of RNA decay factor mediated RNA stability contributions on RNA abundance. BMC Genomics 2015; 16:154. [PMID: 25879614 PMCID: PMC4359779 DOI: 10.1186/s12864-015-1358-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 02/19/2015] [Indexed: 12/28/2022] Open
Abstract
Background Histone epigenome data determined by chromatin immunoprecipitation sequencing (ChIP-seq) is used in identifying transcript regions and estimating expression levels. However, this estimation does not always correlate with eventual RNA expression levels measured by RNA sequencing (RNA-seq). Part of the inconsistency may arise from the variance in RNA stability, where the transcripts that are more or less abundant than predicted RNA expression from histone epigenome data are inferred to be more or less stable. However, there is little systematic analysis to validate this assumption. Here, we used stability data of whole transcriptome measured by 5′-bromouridine immunoprecipitation chase sequencing (BRIC-seq), which enabled us to determine the half-lives of whole transcripts including lincRNAs, and we integrated BRIC-seq with ChIP-seq to achieve better estimation of the eventual transcript levels and to understand the importance of post-transcriptional regulation that determine the eventual transcript levels. Results We identified discrepancies between the RNA abundance estimated by ChIP-seq and measured RNA expression from RNA-seq; for number of genes and estimated that the expression level of 865 genes was controlled at the level of RNA stability in HeLa cells. ENCODE data analysis supported the idea that RNA stability control aids to determine transcript levels in multiple cell types. We identified UPF1, EXOSC5 and STAU1, well-studied RNA degradation factors, as controlling factors for 8% of cases. Computational simulations reasonably explained the changes of eventual mRNA levels attributable to the changes in the rates of mRNA half-lives. In addition, we propose a feedback circuit that includes the regulated degradation of mRNAs encoding transcription factors to maintain the steady state level of RNA abundance. Intriguingly, these regulatory mechanisms were distinct between mRNAs and lincRNAs. Conclusions Integrative analysis of ChIP-seq, RNA-seq and our BRIC-seq showed that transcriptional regulation and RNA degradation are independently regulated. In addition, RNA stability is an important determinant of eventual transcript levels. RNA binding proteins, such as UPF1, STAU1 and EXOSC5 may play active roles in such controls. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-1358-y) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Sho Maekawa
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8562, Japan.
| | - Naoto Imamachi
- Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan.
| | - Takuma Irie
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8562, Japan.
| | - Hidenori Tani
- Research Institute for Environmental Management Technology, National Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki, 305-8569, Japan.
| | - Kyoko Matsumoto
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8562, Japan.
| | - Rena Mizutani
- Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan.
| | - Katsutoshi Imamura
- Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan.
| | - Miho Kakeda
- Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan.
| | - Tetsushi Yada
- Department of Bioscience and Bioinformatics, Kyushu Institute of Technology, 680-4 Kawazu, Iizuka, Fukuoka, 820-8502, Japan.
| | - Sumio Sugano
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8562, Japan.
| | - Yutaka Suzuki
- Department of Medical Genome Sciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8562, Japan. .,Department of Computational Biology, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, 277-8561, Japan.
| | - Nobuyoshi Akimitsu
- Radioisotope Center, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo, 113-0032, Japan.
| |
Collapse
|
15
|
Nonsense-mediated mRNA decay: inter-individual variability and human disease. Neurosci Biobehav Rev 2013; 46 Pt 2:175-86. [PMID: 24239855 DOI: 10.1016/j.neubiorev.2013.10.016] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Revised: 10/29/2013] [Accepted: 10/30/2013] [Indexed: 01/09/2023]
Abstract
Nonsense-mediated mRNA decay (NMD) is a regulatory pathway that functions to degrade transcripts containing premature termination codons (PTCs) and to maintain normal transcriptome homeostasis. Nonsense and frameshift mutations that generate PTCs cause approximately one-third of all known human genetic diseases and thus NMD has a potentially important role in human disease. In genetic disorders in which the affected genes carry PTC-generating mutations, NMD acts as a double-edge sword. While it can benefit the patient by degrading PTC-containing mRNAs that encode detrimental, dominant-negative truncated proteins, it can also make the disease worse when a PTC-containing mRNA is degraded that encodes a mutant but still functional protein. There is evidence that the magnitude of NMD varies between individuals, which, in turn, has been shown to correlate with both clinical presentations and the patients' responses to drugs that promote read-through of PTCs. In this review, we examine the evidence supporting the existence of inter-individual variability in NMD efficiency and discuss the genetic factors that underlie this variability. We propose that inter-individual variability in NMD efficiency is a common phenomenon in human populations and that an individual's NMD efficiency should be taken into consideration when testing, developing, and making therapeutic decisions for diseases caused by genes harboring PTCs.
Collapse
|
16
|
Jolly LA, Homan CC, Jacob R, Barry S, Gecz J. The UPF3B gene, implicated in intellectual disability, autism, ADHD and childhood onset schizophrenia regulates neural progenitor cell behaviour and neuronal outgrowth. Hum Mol Genet 2013; 22:4673-87. [PMID: 23821644 DOI: 10.1093/hmg/ddt315] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Loss-of-function mutations in UPF3B result in variable clinical presentations including intellectual disability (ID, syndromic and non-syndromic), autism, childhood onset schizophrenia and attention deficit hyperactivity disorder. UPF3B is a core member of the nonsense-mediated mRNA decay (NMD) pathway that functions to rapidly degrade transcripts with premature termination codons (PTCs). Traditionally identified in thousands of human diseases, PTCs were recently also found to be part of 'normal' genetic variation in human populations. Furthermore, many human transcripts have naturally occurring regulatory features compatible with 'endogenous' PTCs strongly suggesting roles of NMD beyond PTC mRNA control. In this study, we investigated the role of Upf3b and NMD in neural cells. We provide evidence that suggests Upf3b-dependent NMD (Upf3b-NMD) is regulated at multiple levels during development including regulation of expression and sub-cellular localization of Upf3b. Furthermore, complementary expression of Upf3b, Upf3a and Stau1 stratify the developing dorsal telencephalon, suggesting that alternative NMD, and the related Staufen1-mediated mRNA decay (SMD) pathways are differentially employed. A loss of Upf3b-NMD in neural progenitor cells (NPCs) resulted in the expansion of cell numbers at the expense of their differentiation. In primary hippocampal neurons, loss of Upf3b-NMD resulted in subtle neurite growth effects. Our data suggest that the cellular consequences of loss of Upf3b-NMD can be explained in-part by changes in expression of key NMD-feature containing transcripts, which are commonly deregulated also in patients with UPF3B mutations. Our research identifies novel pathological mechanisms of UPF3B mutations and at least partly explains the clinical phenotype of UPF3B patients.
Collapse
Affiliation(s)
- Lachlan A Jolly
- Department of Genetic and Molecular Pathology, SA Pathology, North Adelaide 5006, Australia
| | | | | | | | | |
Collapse
|
17
|
Non-structural protein 1 of influenza viruses inhibits rapid mRNA degradation mediated by double-stranded RNA-binding protein, staufen1. FEBS Lett 2013; 587:2118-24. [DOI: 10.1016/j.febslet.2013.05.029] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 04/25/2013] [Accepted: 05/01/2013] [Indexed: 11/18/2022]
|
18
|
Park E, Maquat LE. Staufen-mediated mRNA decay. WILEY INTERDISCIPLINARY REVIEWS-RNA 2013; 4:423-35. [PMID: 23681777 DOI: 10.1002/wrna.1168] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 03/28/2013] [Accepted: 03/28/2013] [Indexed: 12/26/2022]
Abstract
Staufen1 (STAU1)-mediated mRNA decay (SMD) is an mRNA degradation process in mammalian cells that is mediated by the binding of STAU1 to a STAU1-binding site (SBS) within the 3'-untranslated region (3'-UTR) of target mRNAs. During SMD, STAU1, a double-stranded (ds) RNA-binding protein, recognizes dsRNA structures formed either by intramolecular base pairing of 3'-UTR sequences or by intermolecular base pairing of 3'-UTR sequences with a long-noncoding RNA (lncRNA) via partially complementary Alu elements. Recently, STAU2, a paralog of STAU1, has also been reported to mediate SMD. Both STAU1 and STAU2 interact directly with the ATP-dependent RNA helicase UPF1, a key SMD factor, enhancing its helicase activity to promote effective SMD. Moreover, STAU1 and STAU2 form homodimeric and heterodimeric interactions via domain-swapping. Because both SMD and the mechanistically related nonsense-mediated mRNA decay (NMD) employ UPF1; SMD and NMD are competitive pathways. Competition contributes to cellular differentiation processes, such as myogenesis and adipogenesis, placing SMD at the heart of various physiologically important mechanisms.
Collapse
Affiliation(s)
- Eonyoung Park
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, Center for RNA Biology, University of Rochester, Rochester, NY, USA
| | | |
Collapse
|
19
|
Abstract
Staufen1-mediated mRNA decay (SMD) degrades mRNAs that harbor a Staufen1-binding site (SBS) in their 3' untranslated regions (UTRs). Human SBSs can form by intermolecular base-pairing between a 3' UTR Alu element and an Alu element within a long noncoding RNA (lncRNA) called a ½-sbsRNA. Since Alu elements are confined to primates, it was unclear how SMD occurs in rodents. Here we identify mouse mRNA 3' UTRs and lncRNAs that contain a B1, B2, B4, or identifier (ID) element. We show that SMD occurs in mouse cells via mRNA-lncRNA base-pairing of partially complementary elements and that mouse ½-sbsRNA (m½-sbsRNA)-triggered SMD regulates C2C12 cell myogenesis. Our findings define new roles for lncRNAs as well as B and ID short interspersed elements (SINEs) in mice that undoubtedly influence many developmental and homeostatic pathways.
Collapse
Affiliation(s)
- Jiashi Wang
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, Rochester, New York 14642, USA
| | | | | |
Collapse
|
20
|
Staufen1 dimerizes through a conserved motif and a degenerate dsRNA-binding domain to promote mRNA decay. Nat Struct Mol Biol 2013; 20:515-24. [PMID: 23524536 PMCID: PMC4096160 DOI: 10.1038/nsmb.2528] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 02/05/2013] [Indexed: 11/23/2022]
Abstract
Staufen (STAU)1-mediated mRNA decay (SMD) degrades mammalian-cell mRNAs that bind the double-stranded (ds)RNA-binding protein STAU1 in their 3′-untranslated region. We report a new motif, which typifies STAU homologs from all vertebrate classes, that is responsible for human (h)STAU1 homodimerization. Our crystal structure and mutagenesis analyses reveal that this motif, now named the Staufen-swapping motif (SSM), and dsRNA-binding domain 5 (‘RBD’5) mediate protein dimerization: the two SSM α-helices of one molecule interact primarily through a hydrophobic patch with the two ‘RBD’5 α-helices of a second molecule. ‘RBD’5 adopts the canonical α-β-β-β-α fold of a functional RBD, but it lacks residues and features needed to bind duplex RNA. In cells, SSM-mediated hSTAU1 dimerization increases the efficiency of SMD by augmenting hSTAU1 binding to the ATP-dependent RNA helicase hUPF1. Dimerization regulates keratinocyte-mediated wound-healing and, undoubtedly, many other cellular processes.
Collapse
|
21
|
Yap K, Makeyev EV. Regulation of gene expression in mammalian nervous system through alternative pre-mRNA splicing coupled with RNA quality control mechanisms. Mol Cell Neurosci 2013; 56:420-8. [PMID: 23357783 DOI: 10.1016/j.mcn.2013.01.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2012] [Revised: 01/15/2013] [Accepted: 01/17/2013] [Indexed: 12/12/2022] Open
Abstract
Eukaryotic gene expression is orchestrated on a genome-wide scale through several post-transcriptional mechanisms. Of these, alternative pre-mRNA splicing expands the proteome diversity and modulates mRNA stability through downstream RNA quality control (QC) pathways including nonsense-mediated decay (NMD) of mRNAs containing premature termination codons and nuclear retention and elimination (NRE) of intron-containing transcripts. Although originally identified as mechanisms for eliminating aberrant transcripts, a growing body of evidence suggests that NMD and NRE coupled with deliberate changes in pre-mRNA splicing patterns are also used in a number of biological contexts for deterministic control of gene expression. Here we review recent studies elucidating molecular mechanisms and biological significance of these gene regulation strategies with a specific focus on their roles in nervous system development and physiology. This article is part of a Special Issue entitled 'RNA and splicing regulation in neurodegeneration'.
Collapse
Affiliation(s)
- Karen Yap
- School of Biological Sciences, Nanyang Technological University, Singapore 637551, Singapore
| | | |
Collapse
|
22
|
Tani H, Imamachi N, Salam KA, Mizutani R, Ijiri K, Irie T, Yada T, Suzuki Y, Akimitsu N. Identification of hundreds of novel UPF1 target transcripts by direct determination of whole transcriptome stability. RNA Biol 2012; 9:1370-9. [PMID: 23064114 DOI: 10.4161/rna.22360] [Citation(s) in RCA: 135] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
UPF1 eliminates aberrant mRNAs harboring premature termination codons, and regulates the steady-state levels of normal physiological mRNAs. Although genome-wide studies of UPF1 targets performed, previous studies did not distinguish indirect UPF1 targets because they could not determine UPF1-dependent altered RNA stabilities. Here, we measured the decay rates of the whole transcriptome in UPF1-depleted HeLa cells using BRIC-seq, an inhibitor-free method for directly measuring RNA stability. We determined the half-lives and expression levels of 9,229 transcripts. An amount of 785 transcripts were stabilized in UPF1-depleted cells. Among these, the expression levels of 76 transcripts were increased, but those of the other 709 transcripts were not altered. RNA immunoprecipitation showed UPF1 bound to the stabilized transcripts, suggesting that UPF1 directly degrades the 709 transcripts. Many UPF1 targets in this study were newly identified. This study clearly demonstrates that direct determination of RNA stability is a powerful approach for identifying targets of RNA degradation factors.
Collapse
Affiliation(s)
- Hidenori Tani
- Radioisotope Center, University of Tokyo, Tokyo, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Cho H, Kim KM, Han S, Choe J, Park SG, Choi SS, Kim YK. Staufen1-mediated mRNA decay functions in adipogenesis. Mol Cell 2012; 46:495-506. [PMID: 22503102 DOI: 10.1016/j.molcel.2012.03.009] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Revised: 10/28/2011] [Accepted: 03/05/2012] [Indexed: 12/12/2022]
Abstract
The double-stranded RNA binding protein Staufen1 (Stau1) is involved in diverse gene expression pathways. For Stau1-mediated mRNA decay (SMD) in mammals, Stau1 binds to the 3' untranslated region of target mRNA and recruits Upf1 to elicit rapid mRNA degradation. However, the events downstream of Upf1 recruitment and the biological importance of SMD remain unclear. Here we show that SMD involves PNRC2, decapping activity, and 5'-to-3' exonucleolytic activity. In particular, Upf1 serves as an adaptor protein for the association of PNRC2 and Stau1. During adipogenesis, Stau1 and PNRC2 increase in abundance, Upf1 becomes hyperphosphorylated, and consequently SMD efficiency is enhanced. Intriguingly, downregulation of SMD components attenuates adipogenesis in a way that is rescued by downregulation of an antiadipogenic factor, Krüppel-like factor 2 (KLF2), the mRNA of which is identified as a substrate of SMD. Our data thus identify a biological role for SMD in adipogenesis.
Collapse
Affiliation(s)
- Hana Cho
- School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea
| | | | | | | | | | | | | |
Collapse
|
24
|
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.
Collapse
Affiliation(s)
- Shubhendu Ghosh
- Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, Worcester, MA 01655-0122, USA
| | | |
Collapse
|
25
|
Cassar PA, Stanford WL. Integrating post-transcriptional regulation into the embryonic stem cell gene regulatory network. J Cell Physiol 2012; 227:439-49. [PMID: 21503874 DOI: 10.1002/jcp.22787] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Stem cell behavior is orchestrated as a multilayered, concert of gene regulatory mechanisms collectively referred to as the gene regulatory network (GRN). Via cooperative mechanisms, transcriptional, epigenetic, and post-transcriptional regulators activate and repress gene expression to finely regulate stem cell self-renewal and commitment. Due to their tractability, embryonic stem cells (ESCs) serve as the model stem cell to dissect the complexities of the GRN, and discern its relation to stem cell fate. By way of high-throughput genomic analysis, targets of individual gene regulators have been established in ESCs. The compilation of these discrete networks has revealed convergent, multi-dimensional gene regulatory mechanisms involving transcription factors, epigenetic modifiers, non-coding RNA (ncRNA), and RNA-binding proteins. Here we highlight the seminal genomic studies that have shaped our understanding of the ESC GRN and describe alternate post-transcriptional gene regulatory mechanisms that require in depth analyses to draft networks that fully model ESC behavior.
Collapse
Affiliation(s)
- Paul A Cassar
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
| | | |
Collapse
|
26
|
Swisher KD, Parker R. Interactions between Upf1 and the decapping factors Edc3 and Pat1 in Saccharomyces cerevisiae. PLoS One 2011; 6:e26547. [PMID: 22065998 PMCID: PMC3204985 DOI: 10.1371/journal.pone.0026547] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 09/28/2011] [Indexed: 11/18/2022] Open
Abstract
In Saccharomyces cerevisiae, mRNA transcripts with premature termination codons are targeted for deadenylation independent decapping and 5′ to 3′ decay in a quality control pathway termed nonsense-mediated decay (NMD). Critical factors in NMD include Upf1, Upf2, and Upf3, as well as the decapping enzyme, Dcp2/Dcp1. Loss of Upf2 or Upf3 leads to the accumulation of not only Upf1 and Dcp2 in P-bodies, but also of the decapping-activators Pat1, Dhh1, and Lsm1. An interaction between Upf1 and Dcp2 has been identified, which might recruit Dcp2 to the NMD decapping complex. To determine the nature and significance of the Dcp2-Upf1 interaction, we utilized the yeast two-hybrid assay to assess Upf1 interactions with various mRNA decapping factors. We find that although Dcp2 can interact with Upf1, this interaction is indirect and is largely dependent on the Edc3 protein, which interacts with the N-terminal domain of Upf1 at an overlapping, but not identical, site as Upf2. We also found that Pat1 has an independent two-hybrid interaction with the N-terminus of Upf1. Assessment of both reporter and endogenous NMD transcripts suggest that the decapping stimulators, including Edc3 and Pat1, as well as Edc1 and Edc2, are not essential for NMD under normal conditions. This work defines a larger decapping complex involved in NMD, but indicates that components of that complex are not required for general NMD and might either regulate a subset of NMD transcripts or be essential for proper NMD under different environmental conditions.
Collapse
Affiliation(s)
- Kylie D. Swisher
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, United States of America
| | - Roy Parker
- Howard Hughes Medical Institute, University of Arizona, Tucson, Arizona, United States of America
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona, United States of America
- * E-mail:
| |
Collapse
|
27
|
Culp DJ, Robinson B, Parkkila S, Pan PW, Cash MN, Truong HN, Hussey TW, Gullett SL. Oral colonization by Streptococcus mutans and caries development is reduced upon deletion of carbonic anhydrase VI expression in saliva. Biochim Biophys Acta Mol Basis Dis 2011; 1812:1567-76. [PMID: 21945428 DOI: 10.1016/j.bbadis.2011.09.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2011] [Revised: 09/07/2011] [Accepted: 09/09/2011] [Indexed: 12/16/2022]
Abstract
Carbonic anhydrase VI (CA VI), encoded by type A transcripts of the gene Car6, is a secretory product of salivary glands and is found in the enamel pellicle. Because higher caries prevalence is associated with lower salivary concentrations of CA VI in humans, we tested whether CA VI protects enamel surfaces from caries induced by Streptococcus mutans, using Car6(-/-) mice, in which salivary CA VI expression is absent. We detected aberrant Car6 type A transcripts in Car6(-/-) mice, likely targets for nonsense-mediated mRNA decay. Expression of the intracellular stress-induced isoform of CA VI encoded by type B transcripts was restricted to parotid and submandibular glands of wild type mice. The salivary function of Car6(-/-) mice was normal as assessed by the histology and protein/glycoprotein profiles of glands, salivary flow rates and protein/glycoprotein compositions of saliva. Surprisingly, total smooth surface caries and sulcal caries in Car6(-/-) mice were more than 6-fold and 2-fold lower than in wild type mice after infection with S. mutans strain UA159. Recoveries of S. mutans and total microbiota from molars were also lower in Car6(-/-) mice. To explore possible mechanisms for increased caries susceptibility, we found no differences in S. mutans adherence to salivary pellicles, in vitro. Interestingly, higher levels of Lactobacillus murinus and an unidentified Streptococcus species were cultivated from the oral microbiota of Car6(-/-) mice. Collective results suggest salivary CA VI may promote caries by modulating the oral microbiota to favor S. mutans colonization and/or by the enzymatic production of acid within plaque.
Collapse
Affiliation(s)
- David J Culp
- Department of Oral Biology, University of Florida, Gainesville, FL 32610, USA.
| | | | | | | | | | | | | | | |
Collapse
|
28
|
Dickson AM, Wilusz J. Strategies for viral RNA stability: live long and prosper. Trends Genet 2011; 27:286-93. [PMID: 21640425 PMCID: PMC3123725 DOI: 10.1016/j.tig.2011.04.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Revised: 04/21/2011] [Accepted: 04/26/2011] [Indexed: 12/23/2022]
Abstract
Eukaryotic cells have a powerful RNA decay machinery that plays an important and diverse role in regulating both the quantity and the quality of gene expression. Viral RNAs need to successfully navigate around this cellular machinery to initiate and maintain a highly productive infection. Recent work has shown that viruses have developed a variety of strategies to accomplish this, including inherent RNA shields, hijacking host RNA stability factors, incapacitating the host decay machinery and changing the entire landscape of RNA stability in cells using virally encoded nucleases. In addition to maintaining the stability of viral transcripts, these strategies can also contribute to the regulation and complexity of viral gene expression as well as to viral RNA evolution.
Collapse
|
29
|
Chawla R, Redon S, Raftopoulou C, Wischnewski H, Gagos S, Azzalin CM. Human UPF1 interacts with TPP1 and telomerase and sustains telomere leading-strand replication. EMBO J 2011; 30:4047-58. [PMID: 21829167 DOI: 10.1038/emboj.2011.280] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 07/18/2011] [Indexed: 11/09/2022] Open
Abstract
Eukaryotic up-frameshift 1 (UPF1) is a nucleic acid-dependent ATPase and 5'-to-3' helicase, best characterized for its roles in cytoplasmic RNA quality control. We previously demonstrated that human UPF1 binds to telomeres in vivo and its depletion leads to telomere instability. Here, we show that UPF1 is present at telomeres at least during S and G2/M phases and that UPF1 association with telomeres is stimulated by the phosphoinositide 3-kinase (PI3K)-related protein kinase ataxia telangiectasia mutated and Rad3-related (ATR) and by telomere elongation. UPF1 physically interacts with the telomeric factor TPP1 and with telomerase. Akin to UPF1 binding to telomeres, this latter interaction is mediated by ATR. Moreover, the ATPase activity of UPF1 is required to prevent the telomeric defects observed upon UPF1 depletion, and these defects stem predominantly from inefficient telomere leading-strand replication. Our results portray a scenario where UPF1 orchestrates crucial aspects of telomere biology, including telomere replication and telomere length homeostasis.
Collapse
Affiliation(s)
- Raghav Chawla
- Institute of Biochemistry, Eidgenössische Technische Hochschule Zürich (ETHZ), Zürich, Switzerland
| | | | | | | | | | | |
Collapse
|
30
|
Park J, Mehta P, Cooper AA, Veivers D, Heimbach A, Stiller B, Kubisch C, Fung VS, Krainc D, Mackay‐Sim A, Sue CM. Pathogenic effects of novel mutations in the P‐type ATPase
ATP13A2
(
PARK9
) causing Kufor‐Rakeb syndrome, a form of early‐onset parkinsonism. Hum Mutat 2011; 32:956-64. [DOI: 10.1002/humu.21527] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2011] [Accepted: 04/21/2011] [Indexed: 11/10/2022]
Affiliation(s)
- Jin‐Sung Park
- Department of Neurogenetics, Kolling Institute of Medical Research, Royal North Shore Hospital and the University of Sydney, St. Leonards, New South Wales, Australia
| | - Prachi Mehta
- Department of Neurogenetics, Kolling Institute of Medical Research, Royal North Shore Hospital and the University of Sydney, St. Leonards, New South Wales, Australia
| | - Antony A. Cooper
- Garvan Institute of Medical Research and the University of New South Wales, Darlinghurst, New South Wales, Australia
| | - David Veivers
- Department of Neurogenetics, Kolling Institute of Medical Research, Royal North Shore Hospital and the University of Sydney, St. Leonards, New South Wales, Australia
| | - André Heimbach
- Institute of Human Genetics, Center for Molecular Medicine Cologne, and Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases, University of Cologne, Cologne, Germany
| | - Barbara Stiller
- Institute of Human Genetics, Center for Molecular Medicine Cologne, and Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases, University of Cologne, Cologne, Germany
| | - Christian Kubisch
- Institute of Human Genetics, Center for Molecular Medicine Cologne, and Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases, University of Cologne, Cologne, Germany
- Institute of Human Genetics, University of Ulm, Ulm, Germany
| | - Victor S. Fung
- Department of Neurology, Westmead Hospital, Westmead, New South Wales, Australia
| | - Dimitri Krainc
- Department of Neurology, Massachusetts General Hospital, Harvard Medical School, MassGeneral Institute for Neurodegeneration, Charlestown, Massachusetts
| | - Alan Mackay‐Sim
- National Adult Stem Cell Research Centre, Eskitis Institute for Cell and Molecular Therapies, School of Biomolecular and Physical Sciences, Griffith University, Queensland, Australia
| | - Carolyn M. Sue
- Department of Neurogenetics, Kolling Institute of Medical Research, Royal North Shore Hospital and the University of Sydney, St. Leonards, New South Wales, Australia
| |
Collapse
|
31
|
Chiluiza D, Bargo S, Callahan R, Rhoads RE. Expression of truncated eukaryotic initiation factor 3e (eIF3e) resulting from integration of mouse mammary tumor virus (MMTV) causes a shift from cap-dependent to cap-independent translation. J Biol Chem 2011; 286:31288-96. [PMID: 21737453 DOI: 10.1074/jbc.m111.267294] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Integration of mouse mammary tumor virus (MMTV) at the common integration site Int6 occurs in the gene encoding eIF3e, the p48 subunit of translation initiation factor eIF3. Integration is at any of several introns of the Eif3e gene and causes the expression of truncated Eif3e mRNAs. Ectopic expression of the truncated eIF3e protein resulting from integration at intron 5 (3e5) induces malignant transformation, but by an unknown mechanism. Because eIF3e makes up at least part of the binding site for eIF4G, we examined the effects of 3e5 expression on protein synthesis. We developed an NIH3T3 cell line that contains a single copy of the 3e5 sequence at a predetermined genomic site. Co-immunoprecipitation indicated diminished binding of eIF3 to eIF4G, signifying a reduction in recruitment of the mRNA-unwinding machinery to the 43 S preinitiation complex. Cell growth and overall protein synthesis were decreased. Translation driven by the eIF4G-independent hepatitis C virus internal ribosome entry sequence (HCV IRES) in a bicistronic mRNA was increased relative to cap-dependent translation. Endogenous mRNAs encoding XIAP, c-Myc, CYR61, and Pim-1, which are translated in a cap-independent manner, were shifted to heavier polysomes whereas mRNAs encoding GAPDH, actin, L32, and L34, which are translated in a cap-dependent manner, were shifted to lighter polysomes. We propose that expression of 3e5 diminishes eIF4G interaction with eIF3 and causes abnormal gene expression at the translational level. The correlation between up-regulation of cap-independent translation and MMTV-induced tumorigenesis contrasts with the well established model for malignant transformation involving up-regulation of highly cap-dependent translation.
Collapse
Affiliation(s)
- David Chiluiza
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71106, USA
| | | | | | | |
Collapse
|
32
|
Su W, Slepenkov S, Grudzien-Nogalska E, Kowalska J, Kulis M, Zuberek J, Lukaszewicz M, Darzynkiewicz E, Jemielity J, Rhoads RE. Translation, stability, and resistance to decapping of mRNAs containing caps substituted in the triphosphate chain with BH3, Se, and NH. RNA (NEW YORK, N.Y.) 2011; 17:978-88. [PMID: 21447710 PMCID: PMC3078746 DOI: 10.1261/rna.2430711] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2010] [Accepted: 02/15/2011] [Indexed: 05/23/2023]
Abstract
Decapping is an essential step in multiple pathways of mRNA degradation. Previously, we synthesized mRNAs containing caps that were resistant to decapping, both to dissect the various pathways for mRNA degradation and to stabilize mRNA for more sustained protein expression. mRNAs containing an α-β CH(2) group are resistant to in vitro cleavage by the decapping enzyme hDcp2 but poorly translated. mRNAs containing an S substitution at the β-phosphate are well translated but only partially resistant to hDcp2. We now describe seven new cap analogs substituted at the β-phosphate with BH(3) or Se, or substituted at either the α-β or β-γ O with NH. The analogs differ in affinity for eIF4E and efficiency of in vitro incorporation into mRNA by T7 RNA polymerase. Luciferase mRNAs capped with these analogs differ in resistance to hDcp2 hydrolysis in vitro, translational efficiency in rabbit reticulocyte lysate and in HeLa cells, and stability in HeLa cells. Whereas mRNAs capped with m(2)(7,2'-O)Gpp(S)pG were previously found to have the most favorable properties of translational efficiency and stability in mammalian cells, mRNAs capped with m(7)Gpp(BH3)pm(7)G are translated with the same efficiency but are more stable. Interestingly, some mRNAs exhibit a lag of up to 60 min before undergoing first-order decay (t(1/2) ≅ 25 min). Only mRNAs that are efficiently capped, resistant to decapping in vitro, and actively translated have long lag phases.
Collapse
Affiliation(s)
- Wei Su
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130-3932, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Neu-Yilik G, Amthor B, Gehring NH, Bahri S, Paidassi H, Hentze MW, Kulozik AE. Mechanism of escape from nonsense-mediated mRNA decay of human beta-globin transcripts with nonsense mutations in the first exon. RNA (NEW YORK, N.Y.) 2011; 17:843-854. [PMID: 21389146 PMCID: PMC3078734 DOI: 10.1261/rna.2401811] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Accepted: 01/31/2011] [Indexed: 05/30/2023]
Abstract
The degradation of nonsense-mutated β-globin mRNA by nonsense-mediated mRNA decay (NMD) limits the synthesis of C-terminally truncated dominant negative β-globin chains and thus protects the majority of heterozygotes from symptomatic β-thalassemia. β-globin mRNAs with nonsense mutations in the first exon are known to bypass NMD, although current mechanistic models predict that such mutations should activate NMD. A systematic analysis of this enigma reveals that (1) β-globin exon 1 is bisected by a sharp border that separates NMD-activating from NMD-bypassing nonsense mutations and (2) the ability to bypass NMD depends on the ability to reinitiate translation at a downstream start codon. The data presented here thus reconcile the current mechanistic understanding of NMD with the observed failure of a class of nonsense mutations to activate this important mRNA quality-control pathway. Furthermore, our data uncover a reason why the position of a nonsense mutation alone does not suffice to predict the fate of the affected mRNA and its effect on protein expression.
Collapse
Affiliation(s)
- Gabriele Neu-Yilik
- Department of Pediatric Oncology, Hematology and Immunology, University of Heidelberg, Heidelberg, Germany
| | | | | | | | | | | | | |
Collapse
|
34
|
Abstract
Gene expression can be regulated at multiple levels, including transcription, RNA processing, RNA localization, translation and, finally, RNA turnover. RNA degradation may occur at points along the processing pathway or during translation as it undergoes quality control by RNA surveillance systems. Alternatively, mRNAs may be subject to regulated degradation, often mediated by cis-encoded determinants in the mRNA sequence that, through the recruitment of trans factors, determine the fate of the mRNA. The aim of the present review is to highlight mechanisms of regulated and quality-control RNA degradation in eukaryotic cells, with an emphasis on mammals.
Collapse
|
35
|
Abstract
The brain is the most complex organ of the body and it contains the greatest diversity of cell types. Collectively, the cells within the brain express the greatest number of genes encoded within our genome. Inappropriate gene expression within these cells plays a fundamental role in many neuronal diseases. Illuminating the mechanisms responsible for gene expression is key to understanding these diseases. Because of the complexity, however, there is still much to understand about the mechanisms responsible for gene expression in the brain. There are many steps required for a protein to be generated from a gene, and groups who focus on gene expression normally study a single step such as regulation of transcription, mechanisms of RNA processing or control of translation. To address this, experts were brought together at the Gene Expression in Neuronal Disease meeting in Cardiff. This forum provided the latest insights into specific stages of gene expression in the brain and encompassed the complete pathway from DNA to protein. The present article summarizes the meeting talks and related papers in this issue of Biochemical Society Transactions.
Collapse
|