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Monem PC, Arribere JA. A ubiquitin language communicates ribosomal distress. Semin Cell Dev Biol 2024; 154:131-137. [PMID: 36963992 PMCID: PMC10878831 DOI: 10.1016/j.semcdb.2023.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 02/10/2023] [Accepted: 03/16/2023] [Indexed: 03/26/2023]
Abstract
Cells entrust ribosomes with the critical task of identifying problematic mRNAs and facilitating their degradation. Ribosomes must communicate when they encounter and stall on an aberrant mRNA, lest they expose the cell to toxic and disease-causing proteins, or they jeopardize ribosome homeostasis and cellular translation. In recent years, ribosomal ubiquitination has emerged as a central signaling step in this process, and proteomic studies across labs and experimental systems show a myriad of ubiquitination sites throughout the ribosome. Work from many labs zeroed in on ubiquitination in one region of the small ribosomal subunit as being functionally significant, with the balance and exact ubiquitination sites determined by stall type, E3 ubiquitin ligases, and deubiquitinases. This review discusses the current literature surrounding ribosomal ubiquitination during translational stress and considers its role in committing translational complexes to decay.
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Affiliation(s)
- Parissa C Monem
- Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA, USA
| | - Joshua A Arribere
- Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA, USA.
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Viscardi MJ, Arribere JA. NMD targets experience deadenylation during their maturation and endonucleolytic cleavage during their decay. bioRxiv 2023:2023.09.29.560204. [PMID: 37808772 PMCID: PMC10557752 DOI: 10.1101/2023.09.29.560204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Premature stop codon-containing mRNAs can produce truncated and dominantly acting proteins that harm cells. Eukaryotic cells protect themselves by degrading such mRNAs via the Nonsense-Mediated mRNA Decay (NMD) pathway. The precise reactions by which cells attack NMD target mRNAs remain obscure, precluding a mechanistic understanding of NMD and hampering therapeutic efforts to control NMD. A key step in NMD is the decay of the mRNA, which is proposed to occur via several competing models including deadenylation, exonucleolytic decay, and/or endonucleolytic decay. We set out to clarify the relative contributions of these decay mechanisms to NMD, and to identify the role of key factors. Here, we modify and deploy single-molecule nanopore mRNA sequencing to capture full-length NMD targets and their degradation intermediates, and we obtain single-molecule measures of splicing isoform, cleavage state, and poly(A) tail length. We observe robust endonucleolytic cleavage of NMD targets in vivo that depends on the nuclease SMG-6 and we use the occurence of cleavages to identify several known NMD targets. We show that NMD target mRNAs experience deadenylation, but similar to the extent that normal mRNAs experience as they enter the translational pool. Furthermore, we show that a factor (SMG-5) that historically was ascribed a function in deadenylation, is in fact required for SMG-6-mediated cleavage. Our results support a model in which NMD factors act in concert to degrade NMD targets in animals via an endonucleolytic cleavage near the stop codon, and suggest that deadenylation is a normal part of mRNA (and NMD target) maturation rather than a facet unique to NMD. Our work clarifies the route by which NMD target mRNAs are attacked in an animal.
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Affiliation(s)
- Marcus J. Viscardi
- Department of Molecular, Cellular and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA, USA
| | - Joshua A. Arribere
- Department of Molecular, Cellular and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA, USA
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Monem PC, Vidyasagar N, Piatt AL, Sehgal E, Arribere JA. Ubiquitination of stalled ribosomes enables mRNA decay via HBS-1 and NONU-1 in vivo. PLoS Genet 2023; 19:e1010577. [PMID: 36626369 PMCID: PMC9870110 DOI: 10.1371/journal.pgen.1010577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/23/2023] [Accepted: 12/18/2022] [Indexed: 01/11/2023] Open
Abstract
As ribosomes translate the genetic code, they can encounter a variety of obstacles that hinder their progress. If ribosomes stall for prolonged times, cells suffer due to the loss of translating ribosomes and the accumulation of aberrant protein products. Thus to protect cells, stalled ribosomes experience a series of reactions to relieve the stall and degrade the offending mRNA, a process known as No-Go mRNA Decay (NGD). While much of the machinery for NGD is known, the precise ordering of events and factors along this pathway has not been tested. Here, we deploy C. elegans to unravel the coordinated events comprising NGD. Utilizing a novel reporter and forward and reverse genetics, we identify the machinery required for NGD. Our subsequent molecular analyses define a functional requirement for ubiquitination on at least two ribosomal proteins (eS10 and uS10), and we show that ribosomes lacking ubiquitination sites on eS10 and uS10 fail to perform NGD in vivo. We show that the nuclease NONU-1 acts after the ubiquitin ligase ZNF-598, and discover a novel requirement for the ribosome rescue factors HBS-1/PELO-1 in mRNA decay via NONU-1. Taken together, our work demonstrates mechanisms by which ribosomes signal to effectors of mRNA repression, and we delineate links between repressive factors working toward a well-defined NGD pathway.
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Affiliation(s)
- Parissa C. Monem
- Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, California, United States of America
| | - Nitin Vidyasagar
- Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, California, United States of America
| | - Audrey L. Piatt
- Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, California, United States of America
| | - Enisha Sehgal
- Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, California, United States of America
| | - Joshua A. Arribere
- Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, California, United States of America
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Viscardi MJ, Arribere JA. Poly(a) selection introduces bias and undue noise in direct RNA-sequencing. BMC Genomics 2022; 23:530. [PMID: 35869428 PMCID: PMC9306060 DOI: 10.1186/s12864-022-08762-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 07/11/2022] [Indexed: 12/14/2022] Open
Abstract
Background Genome-wide RNA-sequencing technologies are increasingly critical to a wide variety of diagnostic and research applications. RNA-seq users often first enrich for mRNA, with the most popular enrichment method being poly(A) selection. In many applications it is well-known that poly(A) selection biases the view of the transcriptome by selecting for longer tailed mRNA species. Results Here, we show that poly(A) selection biases Oxford Nanopore direct RNA sequencing. As expected, poly(A) selection skews sequenced mRNAs toward longer poly(A) tail lengths. Interestingly, we identify a population of mRNAs (> 10% of genes’ mRNAs) that are inconsistently captured by poly(A) selection due to highly variable poly(A) tails, and demonstrate this phenomenon in our hands and in published data. Importantly, we show poly(A) selection is dispensable for Oxford Nanopore’s direct RNA-seq technique, and demonstrate successful library construction without poly(A) selection, with decreased input, and without loss of quality. Conclusions Our work expands the utility of direct RNA-seq by validating the use of total RNA as input, and demonstrates important technical artifacts from poly(A) selection that inconsistently skew mRNA expression and poly(A) tail length measurements. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-022-08762-8.
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Glover ML, Burroughs AM, Monem PC, Egelhofer TA, Pule MN, Aravind L, Arribere JA. NONU-1 Encodes a Conserved Endonuclease Required for mRNA Translation Surveillance. Cell Rep 2021; 30:4321-4331.e4. [PMID: 32234470 DOI: 10.1016/j.celrep.2020.03.023] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 01/31/2020] [Accepted: 03/06/2020] [Indexed: 12/31/2022] Open
Abstract
Cellular translation surveillance rescues ribosomes that stall on problematic mRNAs. During translation surveillance, endonucleolytic cleavage of the problematic mRNA is a critical step in rescuing stalled ribosomes. Here we identify NONU-1 as a factor required for translation surveillance pathways including no-go and nonstop mRNA decay. We show that (1) NONU-1 reduces nonstop and no-go mRNA levels; (2) NONU-1 contains an Smr RNase domain required for mRNA decay; (3) the domain architecture and catalytic residues of NONU-1 are conserved throughout metazoans and eukaryotes, respectively; and (4) NONU-1 is required for the formation of mRNA cleavage fragments in the vicinity of stalled ribosomes. We extend our results in C. elegans to homologous factors in S. cerevisiae, showing the evolutionarily conserved function of NONU-1. Our work establishes the identity of a factor critical to translation surveillance and will inform mechanistic studies at the intersection of translation and mRNA decay.
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Affiliation(s)
- Marissa L Glover
- Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA, USA
| | - A Max Burroughs
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Parissa C Monem
- Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA, USA
| | - Thea A Egelhofer
- Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA, USA
| | - Makena N Pule
- Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA, USA
| | - L Aravind
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Joshua A Arribere
- Department of Molecular, Cell, and Developmental Biology, University of California at Santa Cruz, Santa Cruz, CA, USA.
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Abstract
While DNA serves as the blueprint of life, the distinct functions of each cell are determined by the dynamic expression of genes from the static genome. The amount and specific sequences of RNAs expressed in a given cell involves a number of regulated processes including RNA synthesis (transcription), processing, splicing, modification, polyadenylation, stability, translation, and degradation. As errors during mRNA production can create gene products that are deleterious to the organism, quality control mechanisms exist to survey and remove errors in mRNA expression and processing. Here, we will provide an overview of mRNA processing and quality control mechanisms that occur in Caenorhabditis elegans, with a focus on those that occur on protein-coding genes after transcription initiation. In addition, we will describe the genetic and technical approaches that have allowed studies in C. elegans to reveal important mechanistic insight into these processes.
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Affiliation(s)
| | - Hidehito Kuroyanagi
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 113-8510, Japan, and
| | - Heather A Hundley
- Medical Sciences Program, Indiana University School of Medicine-Bloomington, Indiana 47405
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Abstract
In the course of identifying and cleaving RNA, the RNAi machinery must encounter and contend with the megadalton-sized ribosomes that carry out translation. We investigated this interface by examining the fate of actively translated mRNAs subjected to RNAi in C. elegans Quantifying RNA levels (RNA-seq) and ongoing translation (Ribo-seq), we found there is a greater fold repression of ongoing translation than expected from loss of RNA alone, observing stronger translation repression relative to RNA repression for multiple, independent double-stranded RNA triggers, and for multiple genes. In animals that lack the RNA helicase SKI complex and the ribosome rescue factor PELOTA, ribosomes stall on the 3' edges of mRNAs at and upstream of the RNAi trigger. One model to explain these observations is that ribosomes are actively cleared from mRNAs by SKI and PELO during or following mRNA cleavage. Our results expand prior studies that show a role for the SKI RNA helicase complex in removing RNA targets following RNAi in flies and plants, illuminating the widespread role of the nonstop translation surveillance in RNA silencing during RNAi. Our results are also consistent with proposals that RNAi can attack messages during active translation.
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Affiliation(s)
- Makena N Pule
- Department of MCD Biology, UC Santa Cruz, Santa Cruz, California 95064, USA
| | - Marissa L Glover
- Department of MCD Biology, UC Santa Cruz, Santa Cruz, California 95064, USA
| | - Andrew Z Fire
- Departments of Pathology and Genetics, Stanford University School of Medicine, Stanford, California 94305, USA
| | - Joshua A Arribere
- Department of MCD Biology, UC Santa Cruz, Santa Cruz, California 95064, USA
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Cenik ES, Meng X, Tang NH, Hall RN, Arribere JA, Cenik C, Jin Y, Fire A. Maternal Ribosomes Are Sufficient for Tissue Diversification during Embryonic Development in C. elegans. Dev Cell 2019; 48:811-826.e6. [PMID: 30799226 DOI: 10.1016/j.devcel.2019.01.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Revised: 11/06/2018] [Accepted: 01/21/2019] [Indexed: 12/20/2022]
Abstract
Caenorhabditis elegans provides an amenable system to explore whether newly composed ribosomes are required to progress through development. Despite the complex pattern of tissues that are formed during embryonic development, we found that null homozygotes lacking any of the five different ribosomal proteins (RPs) can produce fully functional first-stage larvae, with similar developmental competence seen upon complete deletion of the multi-copy ribosomal RNA locus. These animals, relying on maternal but not zygotic contribution of ribosomal components, are capable of completing embryogenesis. In the absence of new ribosomal components, the resulting animals are arrested before progression from the first larval stage and fail in two assays for postembryonic plasticity of neuronal structure. Mosaic analyses of larvae that are a mixture of ribosome-competent and non-competent cells suggest a global regulatory mechanism in which ribosomal insufficiency in a subset of cells triggers organism-wide growth arrest.
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Affiliation(s)
- Elif Sarinay Cenik
- Department of Pathology, Stanford University Medical School, Stanford, CA, USA; Department of Molecular Biosciences, University of Texas Austin, Austin, TX, USA
| | - Xuefeng Meng
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, San Diego, CA, USA
| | - Ngang Heok Tang
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, San Diego, CA, USA
| | | | - Joshua A Arribere
- Department of MCD Biology, University of California, Santa Cruz, Santa Cruz, CA, USA
| | - Can Cenik
- Department of Molecular Biosciences, University of Texas Austin, Austin, TX, USA
| | - Yishi Jin
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, San Diego, CA, USA
| | - Andrew Fire
- Department of Pathology, Stanford University Medical School, Stanford, CA, USA.
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Abstract
Nonsense-mediated mRNA decay is the process by which mRNAs bearing premature stop codons are recognized and cleared from the cell. While considerable information has accumulated regarding recognition of the premature stop codon, less is known about the ensuing mRNA suppression. During the characterization of a second, distinct translational surveillance pathway (nonstop mRNA decay), we trapped intermediates in nonsense mRNA degradation. We present data in support of a model wherein nonsense-mediated decay funnels into the nonstop decay pathway in Caenorhabditis elegans. Specifically, our results point to SKI-exosome decay and pelota-based ribosome removal as key steps facilitating suppression and clearance of prematurely-terminated translation complexes. These results suggest a model in which premature stop codons elicit nucleolytic cleavage, with the nonstop pathway disengaging ribosomes and degrading the resultant RNA fragments to suppress ongoing expression.
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Affiliation(s)
- Joshua A Arribere
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Cruz, Santa Cruz, United States
| | - Andrew Z Fire
- Departments of Pathology and Genetics, Stanford University School of Medicine, Stanford, United States
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Affiliation(s)
- Crystal M. Botham
- Stanford Biosciences Grant Writing Academy, Stanford University, Stanford, California, United States of America
- * E-mail: (CMB); (KTB)
| | - Joshua A. Arribere
- Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, California, United States of America
| | - Sky W. Brubaker
- Department of Microbiology and Immunology, Stanford University, Stanford, California, United States of America
| | - Kevin T. Beier
- Department of Biology, Stanford University, Stanford, California, United States of America
- Department of Psychiatry and Behavioral Sciences, Stanford University, Stanford, California, United States of America
- * E-mail: (CMB); (KTB)
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Abstract
Transcript leaders (TLs) can have profound effects on mRNA translation and stability. To map TL boundaries genome-wide, we developed TL-sequencing (TL-seq), a technique combining enzymatic capture of m7G-capped mRNA 5′ ends with high-throughput sequencing. TL-seq identified mRNA start sites for the majority of yeast genes and revealed many examples of intragenic TL heterogeneity. Surprisingly, TL-seq identified transcription initiation sites within 6% of protein-coding regions, and these sites were concentrated near the 5′ ends of ORFs. Furthermore, ribosome density analysis showed these truncated mRNAs are translated. Translation-associated TL-seq (TATL-seq), which combines TL-seq with polysome fractionation, enabled annotation of TLs, and simultaneously assayed their function in translation. Using TATL-seq to address relationships between TL features and translation of the downstream ORF, we observed that upstream AUGs (uAUGs), and no other upstream codons, were associated with poor translation and nonsense-mediated mRNA decay (NMD). We also identified hundreds of genes with very short TLs, and demonstrated that short TLs were associated with poor translation initiation at the annotated start codon and increased initiation at downstream AUGs. This frequently resulted in out-of-frame translation and subsequent termination at premature termination codons, culminating in NMD of the transcript. Unlike previous approaches, our technique enabled observation of alternative TL variants for hundreds of genes and revealed significant differences in translation in genes with distinct TL isoforms. TL-seq and TATL-seq are useful tools for annotation and functional characterization of TLs, and can be applied to any eukaryotic system to investigate TL-mediated regulation of gene expression.
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Affiliation(s)
- Joshua A Arribere
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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Arribere JA, Doudna JA, Gilbert WV. Reconsidering movement of eukaryotic mRNAs between polysomes and P bodies. Mol Cell 2012; 44:745-58. [PMID: 22152478 DOI: 10.1016/j.molcel.2011.09.019] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2011] [Revised: 06/21/2011] [Accepted: 09/14/2011] [Indexed: 11/19/2022]
Abstract
Cell survival in changing environments requires appropriate regulation of gene expression, including posttranscriptional regulatory mechanisms. From reporter gene studies in glucose-starved yeast, it was proposed that translationally silenced eukaryotic mRNAs accumulate in P bodies and can return to active translation. We present evidence contradicting the notion that reversible storage of nontranslating mRNAs is a widespread and general phenomenon. First, genome-wide measurements of mRNA abundance, translation, and ribosome occupancy after glucose withdrawal show that most mRNAs are depleted from the cell coincident with their depletion from polysomes. Second, only a limited subpopulation of translationally repressed transcripts, comprising fewer than 400 genes, can be reactivated for translation upon glucose readdition in the absence of new transcription. This highly selective posttranscriptional regulation could be a mechanism for cells to minimize the energetic costs of reversing gene-regulatory decisions in rapidly changing environments by transiently preserving a pool of transcripts whose translation is rate-limiting for growth.
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Affiliation(s)
- Joshua A Arribere
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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