1
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Malik Y, Goncalves Silva I, Diazgranados RR, Selman C, Alic N, Tullet JM. Timing of TORC1 inhibition dictates Pol III involvement in Caenorhabditis elegans longevity. Life Sci Alliance 2024; 7:e202402735. [PMID: 38740431 DOI: 10.26508/lsa.202402735] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 04/25/2024] [Accepted: 04/26/2024] [Indexed: 05/16/2024] Open
Abstract
Organismal growth and lifespan are inextricably linked. Target of Rapamycin (TOR) signalling regulates protein production for growth and development, but if reduced, extends lifespan across species. Reduction in the enzyme RNA polymerase III, which transcribes tRNAs and 5S rRNA, also extends longevity. Here, we identify a temporal genetic relationship between TOR and Pol III in Caenorhabditis elegans, showing that they collaborate to regulate progeny production and lifespan. Interestingly, the lifespan interaction between Pol III and TOR is only revealed when TOR signaling is reduced, specifically in adulthood, demonstrating the importance of timing to control TOR regulated developmental versus adult programs. In addition, we show that Pol III acts in C. elegans muscle to promote both longevity and healthspan and that reducing Pol III even in late adulthood is sufficient to extend lifespan. This demonstrates the importance of Pol III for lifespan and age-related health in adult C. elegans.
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Affiliation(s)
- Yasir Malik
- https://ror.org/00xkeyj56 Division of Natural Sciences, School of Biosciences, University of Kent, Canterbury, Kent
| | - Isabel Goncalves Silva
- https://ror.org/00xkeyj56 Division of Natural Sciences, School of Biosciences, University of Kent, Canterbury, Kent
| | - Rene Rivera Diazgranados
- https://ror.org/00xkeyj56 Division of Natural Sciences, School of Biosciences, University of Kent, Canterbury, Kent
| | - Colin Selman
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, Scotland
| | - Nazif Alic
- UCL Department of Genetics, Evolution & Environment, Institute of Healthy Ageing, London, UK
| | - Jennifer Ma Tullet
- https://ror.org/00xkeyj56 Division of Natural Sciences, School of Biosciences, University of Kent, Canterbury, Kent
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2
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Kapur M, Molumby MJ, Guzman C, Heinz S, Ackerman SL. Cell-type-specific expression of tRNAs in the brain regulates cellular homeostasis. Neuron 2024; 112:1397-1415.e6. [PMID: 38377989 PMCID: PMC11065635 DOI: 10.1016/j.neuron.2024.01.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 12/23/2023] [Accepted: 01/29/2024] [Indexed: 02/22/2024]
Abstract
Defects in tRNA biogenesis are associated with multiple neurological disorders, yet our understanding of these diseases has been hampered by an inability to determine tRNA expression in individual cell types within a complex tissue. Here, we developed a mouse model in which RNA polymerase III is conditionally epitope tagged in a Cre-dependent manner, allowing us to accurately profile tRNA expression in any cell type in vivo. We investigated tRNA expression in diverse nervous system cell types, revealing dramatic heterogeneity in the expression of tRNA genes between populations. We found that while maintenance of levels of tRNA isoacceptor families is critical for cellular homeostasis, neurons are differentially vulnerable to insults to distinct tRNA isoacceptor families. Cell-type-specific translatome analysis suggests that the balance between tRNA availability and codon demand may underlie such differential resilience. Our work provides a platform for investigating the complexities of mRNA translation and tRNA biology in the brain.
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Affiliation(s)
- Mridu Kapur
- Department of Cellular and Molecular Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093, USA; The Howard Hughes Medical Institute
| | - Michael J Molumby
- Department of Cellular and Molecular Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093, USA; The Howard Hughes Medical Institute
| | - Carlos Guzman
- Department of Medicine, Division of Endocrinology, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Department of Bioengineering, Bioinformatics & Systems Biology Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Sven Heinz
- Department of Medicine, Division of Endocrinology, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA; Department of Bioengineering, Bioinformatics & Systems Biology Graduate Program, University of California, San Diego, La Jolla, CA 92093, USA
| | - Susan L Ackerman
- Department of Cellular and Molecular Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093, USA; The Howard Hughes Medical Institute; Department of Neurobiology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA.
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3
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Gao L, Behrens A, Rodschinka G, Forcelloni S, Wani S, Strasser K, Nedialkova DD. Selective gene expression maintains human tRNA anticodon pools during differentiation. Nat Cell Biol 2024; 26:100-112. [PMID: 38191669 PMCID: PMC10791582 DOI: 10.1038/s41556-023-01317-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 11/16/2023] [Indexed: 01/10/2024]
Abstract
Transfer RNAs are essential for translating genetic information into proteins. The human genome contains hundreds of predicted tRNA genes, many in multiple copies. How their expression is regulated to control tRNA repertoires is unknown. Here we combined quantitative tRNA profiling and chromatin immunoprecipitation with sequencing to measure tRNA expression following the differentiation of human induced pluripotent stem cells into neuronal and cardiac cells. We find that tRNA transcript levels vary substantially, whereas tRNA anticodon pools, which govern decoding rates, are more stable among cell types. Mechanistically, RNA polymerase III transcribes a wide range of tRNA genes in human induced pluripotent stem cells but on differentiation becomes constrained to a subset we define as housekeeping tRNAs. This shift is mediated by decreased mTORC1 signalling, which activates the RNA polymerase III repressor MAF1. Our data explain how tRNA anticodon pools are buffered to maintain decoding speed across cell types and reveal that mTORC1 drives selective tRNA expression during differentiation.
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Affiliation(s)
- Lexi Gao
- Mechanisms of Protein Biogenesis, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Andrew Behrens
- Mechanisms of Protein Biogenesis, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Geraldine Rodschinka
- Mechanisms of Protein Biogenesis, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Sergio Forcelloni
- Mechanisms of Protein Biogenesis, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Sascha Wani
- Mechanisms of Protein Biogenesis, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Katrin Strasser
- Mechanisms of Protein Biogenesis, Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Danny D Nedialkova
- Mechanisms of Protein Biogenesis, Max Planck Institute of Biochemistry, Martinsried, Germany.
- Department of Bioscience, TUM School of Natural Sciences, Technical University of Munich, Garching, Germany.
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4
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Chen H, Ma L, Yang W, Li Y, Ji Z. POLR3G promotes EMT via PI3K/AKT signaling pathway in bladder cancer. FASEB J 2023; 37:e23260. [PMID: 37933949 DOI: 10.1096/fj.202301095r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 09/07/2023] [Accepted: 09/28/2023] [Indexed: 11/08/2023]
Abstract
RNA Polymerase III Subunit G (POLR3G) promotes tumorigenesis, metastasis, cancer stemness, and chemoresistance of breast cancer and lung cancer; however, its biological function in bladder cancer (BLCA) remains unclear. Through bioinformatic analyses, we found that POLR3G expression was significantly elevated in BLCA tumor tissues and was associated with decreased survival. Multivariate Cox analysis indicated that POLR3G could serve as an independent prognostic risk factor. Our functional investigations revealed that POLR3G deficiency resulted in reduced migration and invasion of BLCA cells both in vitro and in vivo. Additionally, the expressions of EMT-related mesenchymal markers were also downregulated in POLR3G knockdown cells. Mechanistically, we showed that POLR3G could activate the PI3K/AKT signaling pathway. Inhibition of this pathway with LY294002 reduced the enhanced migration and invasion of BLCA cells induced by POLR3G overexpression, whereas the activation of this pathway using 740Y-P restored the abilities that were inhibited by POLR3G knockdown. Taken together, our findings suggested that POLR3G is a prognostic predictor for BLCA and promotes EMT of BLCA through activation of the PI3K/AKT signaling pathway.
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Affiliation(s)
- Hualin Chen
- Department of Urology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Lin Ma
- Department of Urology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Wenjie Yang
- Department of Urology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Yingjie Li
- Department of Urology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Zhigang Ji
- Department of Urology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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5
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Goldtzvik Y, Sen N, Lam SD, Orengo C. Protein diversification through post-translational modifications, alternative splicing, and gene duplication. Curr Opin Struct Biol 2023; 81:102640. [PMID: 37354790 DOI: 10.1016/j.sbi.2023.102640] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Revised: 05/05/2023] [Accepted: 05/24/2023] [Indexed: 06/26/2023]
Abstract
Proteins provide the basis for cellular function. Having multiple versions of the same protein within a single organism provides a way of regulating its activity or developing novel functions. Post-translational modifications of proteins, by means of adding/removing chemical groups to amino acids, allow for a well-regulated and controlled way of generating functionally distinct protein species. Alternative splicing is another method with which organisms possibly generate new isoforms. Additionally, gene duplication events throughout evolution generate multiple paralogs of the same genes, resulting in multiple versions of the same protein within an organism. In this review, we discuss recent advancements in the study of these three methods of protein diversification and provide illustrative examples of how they affect protein structure and function.
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Affiliation(s)
- Yonathan Goldtzvik
- Department of Structural and Molecular Biology, University College London, London, United Kingdom
| | - Neeladri Sen
- Department of Structural and Molecular Biology, University College London, London, United Kingdom. https://twitter.com/@NeeladriSen
| | - Su Datt Lam
- Department of Structural and Molecular Biology, University College London, London, United Kingdom; Department of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, Bangi, Malaysia
| | - Christine Orengo
- Department of Structural and Molecular Biology, University College London, London, United Kingdom.
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6
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Macintosh J, Michell-Robinson M, Chen X, Bernard G. Decreased RNA polymerase III subunit expression leads to defects in oligodendrocyte development. Front Neurosci 2023; 17:1167047. [PMID: 37179550 PMCID: PMC10167296 DOI: 10.3389/fnins.2023.1167047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 03/31/2023] [Indexed: 05/15/2023] Open
Abstract
Introduction RNA polymerase III (Pol III) is a critical enzymatic complex tasked with the transcription of ubiquitous non-coding RNAs including 5S rRNA and all tRNA genes. Despite the constitutive nature of this enzyme, hypomorphic biallelic pathogenic variants in genes encoding subunits of Pol III lead to tissue-specific features and cause a hypomyelinating leukodystrophy, characterized by a severe and permanent deficit in myelin. The pathophysiological mechanisms in POLR3- related leukodystrophy and specifically, how reduced Pol III function impacts oligodendrocyte development to account for the devastating hypomyelination seen in the disease, remain poorly understood. Methods In this study, we characterize how reducing endogenous transcript levels of leukodystrophy-associated Pol III subunits affects oligodendrocyte maturation at the level of their migration, proliferation, differentiation, and myelination. Results Our results show that decreasing Pol III expression altered the proliferation rate of oligodendrocyte precursor cells but had no impact on migration. Additionally, reducing Pol III activity impaired the differentiation of these precursor cells into mature oligodendrocytes, evident at both the level of OL-lineage marker expression and on morphological assessment, with Pol III knockdown cells displaying a drastically more immature branching complexity. Myelination was hindered in the Pol III knockdown cells, as determined in both organotypic shiverer slice cultures and co-cultures with nanofibers. Analysis of Pol III transcriptional activity revealed a decrease in the expression of distinct tRNAs, which was significant in the siPolr3a condition. Discussion In turn, our findings provide insight into the role of Pol III in oligodendrocyte development and shed light on the pathophysiological mechanisms of hypomyelination in POLR3-related leukodystrophy.
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Affiliation(s)
- Julia Macintosh
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Center, Montreal, QC, Canada
| | - Mackenzie Michell-Robinson
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Center, Montreal, QC, Canada
| | - Xiaoru Chen
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Center, Montreal, QC, Canada
| | - Geneviève Bernard
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
- Child Health and Human Development Program, Research Institute of the McGill University Health Center, Montreal, QC, Canada
- Department of Pediatrics, McGill University, Montreal, QC, Canada
- Department of Human Genetics, McGill University, Montreal, QC, Canada
- Department of Specialized Medicine, Division of Medical Genetics, McGill University Health Center, Montreal, QC, Canada
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7
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Watt KE, Macintosh J, Bernard G, Trainor PA. RNA Polymerases I and III in development and disease. Semin Cell Dev Biol 2023; 136:49-63. [PMID: 35422389 PMCID: PMC9550887 DOI: 10.1016/j.semcdb.2022.03.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 03/18/2022] [Accepted: 03/21/2022] [Indexed: 12/18/2022]
Abstract
Ribosomes are macromolecular machines that are globally required for the translation of all proteins in all cells. Ribosome biogenesis, which is essential for cell growth, proliferation and survival, commences with transcription of a variety of RNAs by RNA Polymerases I and III. RNA Polymerase I (Pol I) transcribes ribosomal RNA (rRNA), while RNA Polymerase III (Pol III) transcribes 5S ribosomal RNA and transfer RNAs (tRNA) in addition to a wide variety of small non-coding RNAs. Interestingly, despite their global importance, disruptions in Pol I and Pol III function result in tissue-specific developmental disorders, with craniofacial anomalies and leukodystrophy/neurodegenerative disease being among the most prevalent. Furthermore, pathogenic variants in genes encoding subunits shared between Pol I and Pol III give rise to distinct syndromes depending on whether Pol I or Pol III function is disrupted. In this review, we discuss the global roles of Pol I and III transcription, the consequences of disruptions in Pol I and III transcription, disorders arising from pathogenic variants in Pol I and Pol III subunits, and mechanisms underpinning their tissue-specific phenotypes.
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Affiliation(s)
- Kristin En Watt
- Stowers Institute for Medical Research, Kansas City, MO, USA
| | - Julia Macintosh
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada; Child Health and Human Development Program, Research Institute of the McGill University Health Center, Montreal, QC, Canada
| | - Geneviève Bernard
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada; Child Health and Human Development Program, Research Institute of the McGill University Health Center, Montreal, QC, Canada; Departments of Pediatrics and Human Genetics, McGill University, Montreal, QC, Canada; Department of Specialized Medicine, Division of Medical Genetics, McGill University Health Center, Montreal, QC, Canada.
| | - Paul A Trainor
- Stowers Institute for Medical Research, Kansas City, MO, USA; Department of Anatomy & Cell Biology, University of Kansas Medical Center, Kansas City, KS, USA.
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8
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Cheng R, Van Bortle K. RNA polymerase III transcription and cancer: A tale of two RPC7 subunits. Front Mol Biosci 2023; 9:1073795. [PMID: 36710885 PMCID: PMC9877311 DOI: 10.3389/fmolb.2022.1073795] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Accepted: 12/19/2022] [Indexed: 01/15/2023] Open
Abstract
RNA polymerase III composition is shaped by the mutually exclusive incorporation of two paralogous subunits, RPC7α and RPC7β, encoded by genes POLR3G and POLR3GL in vertebrates. The expression of POLR3G and POLR3GL is spatiotemporally regulated during development, and multiple reports point to RPC7α-enhanced Pol III activity patterns, indicating that Pol III identity may underly dynamic Pol III transcription patterns observed in higher eukaryotes. In cancer, upregulation of POLR3G, but not POLR3GL, is associated with poor survival outcomes among patients, suggesting differences between RPC7α and RPC7β further influence disease progression and may translate into future biomarkers and therapeutic strategies. Here, we outline our current understanding of Pol III identity and transcription and reexamine the distinct protein characteristics of Pol III subunits RPC7α and RPC7β. Drawing on both structural and genomic studies, we discuss differences between RPC7α and RPC7β and the potential mechanisms by which Pol III identity may establish differential activities during development and disease.
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Affiliation(s)
- Ruiying Cheng
- Department of Cell and Developmental Biology, University of Illinois Urbana-Champaign, Urbana, IL, United States
| | - Kevin Van Bortle
- Department of Cell and Developmental Biology, University of Illinois Urbana-Champaign, Urbana, IL, United States
- Cancer Center at Illinois, University of Illinois Urbana-Champaign, Urbana, IL, United States
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9
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The POLR3G Subunit of Human RNA Polymerase III Regulates Tumorigenesis and Metastasis in Triple-Negative Breast Cancer. Cancers (Basel) 2022; 14:cancers14235732. [PMID: 36497214 PMCID: PMC9735567 DOI: 10.3390/cancers14235732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/10/2022] [Accepted: 11/14/2022] [Indexed: 11/24/2022] Open
Abstract
RNA polymerase (Pol) III transcribes short untranslated RNAs that contribute to the regulation of gene expression. Two isoforms of human Pol III have been described that differ by the presence of the POLR3G/RPC32α or POLR3GL/RPC32β subunits. POLR3G was found to be expressed in embryonic stem cells and at least a subset of transformed cells, whereas POLR3GL shows a ubiquitous expression pattern. Here, we demonstrate that POLR3G is specifically overexpressed in clinical samples of triple-negative breast cancer (TNBC) but not in other molecular subtypes of breast cancer. POLR3G KO in the MDA-MB231 TNBC cell line dramatically reduces anchorage-independent growth and invasive capabilities in vitro. In addition, the POLR3G KO impairs tumor growth and metastasis formation of orthotopic xenografts in mice. Moreover, KO of POLR3G induces expression of the pioneer transcription factor FOXA1 and androgen receptor. In contrast, the POLR3G KO neither alters proliferation nor the expression of epithelial-mesenchymal transition marker genes. These data demonstrate that POLR3G expression is required for TNBC tumor growth, invasiveness and dissemination and that its deletion affects triple-negative breast cancer-specific gene expression.
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10
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Van Bortle K, Marciano DP, Liu Q, Chou T, Lipchik AM, Gollapudi S, Geller BS, Monte E, Kamakaka RT, Snyder MP. A cancer-associated RNA polymerase III identity drives robust transcription and expression of snaR-A noncoding RNA. Nat Commun 2022; 13:3007. [PMID: 35637192 PMCID: PMC9151912 DOI: 10.1038/s41467-022-30323-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 04/13/2022] [Indexed: 11/09/2022] Open
Abstract
RNA polymerase III (Pol III) includes two alternate isoforms, defined by mutually exclusive incorporation of subunit POLR3G (RPC7α) or POLR3GL (RPC7β), in mammals. The contributions of POLR3G and POLR3GL to transcription potential has remained poorly defined. Here, we discover that loss of subunit POLR3G is accompanied by a restricted repertoire of genes transcribed by Pol III. Particularly sensitive is snaR-A, a small noncoding RNA implicated in cancer proliferation and metastasis. Analysis of Pol III isoform biases and downstream chromatin features identifies loss of POLR3G and snaR-A during differentiation, and conversely, re-establishment of POLR3G gene expression and SNAR-A gene features in cancer contexts. Our results support a model in which Pol III identity functions as an important transcriptional regulatory mechanism. Upregulation of POLR3G, which is driven by MYC, identifies a subgroup of patients with unfavorable survival outcomes in specific cancers, further implicating the POLR3G-enhanced transcription repertoire as a potential disease factor. RNA polymerase III changes its subunit composition during mammalian development. Here the authors report that loss of subunit POLR3G, which re-emerges in cancer, promotes expression of small NF90-associated RNA (snaR-A), a noncoding RNA implicated in cell proliferation and metastasis.
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11
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Busschers E, Ahmad N, Sun L, Iben JR, Walkey CJ, Rusin A, Yuen T, Rosen CJ, Willis IM, Zaidi M, Johnson DL. MAF1, a repressor of RNA polymerase III-dependent transcription, regulates bone mass. eLife 2022; 11:74740. [PMID: 35611941 PMCID: PMC9212997 DOI: 10.7554/elife.74740] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 04/26/2022] [Indexed: 11/25/2022] Open
Abstract
MAF1, a key repressor of RNA polymerase (pol) III-mediated transcription, has been shown to promote mesoderm formation in vitro. Here, we show that MAF1 plays a critical role in regulating osteoblast differentiation and bone mass. Global deletion of MAF1 (Maf1-/- mice) produced a high bone mass phenotype. However, osteoblasts isolated from Maf1-/- mice showed reduced osteoblastogenesis ex vivo. Therefore, we determined the phenotype of mice overexpressing MAF1 in cells from the mesenchymal lineage (Prx1-Cre;LSL-MAF1 mice). These mice showed increased bone mass. Ex vivo, cells from these mice showed enhanced osteoblastogenesis concordant with their high bone mass phenotype. Thus, the high bone mass phenotype in Maf1-/- mice is likely due to confounding effects from the global absence of MAF1. MAF1 overexpression promoted osteoblast differentiation of ST2 cells while MAF1 downregulation inhibited differentiation, indicating MAF1 enhances osteoblast formation. However, other perturbations used to repress RNA pol III transcription, inhibited osteoblast differentiation. However, decreasing RNA pol III transcription through these perturbations enhanced adipogenesis in ST2 cells. RNA-seq analyzed the basis for these opposing actions on osteoblast differentiation. The different modalities used to perturb RNA pol III transcription resulted in distinct gene expression changes, indicating that this transcription process is highly sensitive and triggers diverse gene expression programs and phenotypic outcomes. Specifically, MAF1 induced genes known to promote osteoblast differentiation. Furthermore, genes that are induced during osteoblast differentiation displayed codon bias. Together, these results reveal a novel role for MAF1 and RNA pol III-mediated transcription in osteoblast fate determination, differentiation, and bone mass regulation.
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Affiliation(s)
- Ellen Busschers
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, United States
| | - Naseer Ahmad
- Department of Medicine, Ican School of Medicine at Mount Sinai, New York, United States
| | - Li Sun
- Department of Medicine, Ican School of Medicine at Mount Sinai, New York, United States
| | - James R Iben
- Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, United States
| | - Christopher J Walkey
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, United States
| | - Aleksandra Rusin
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, United States
| | - Tony Yuen
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, United States
| | - Clifford J Rosen
- Maine Medical Center Research Institute, Scarborough, United States
| | - Ian M Willis
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, United States
| | - Mone Zaidi
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, United States
| | - Deborah L Johnson
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, United States
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12
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Luo Y, Zhang B, Geng N, Sun S, Song X, Chen J, Zhang H. Transcriptomics and metabolomics analyses provide insights into the difference in toxicity of benzo[a]pyrene and 6-chlorobenzo[a]pyrene to human hepatic cells. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 812:152242. [PMID: 34919925 DOI: 10.1016/j.scitotenv.2021.152242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 12/03/2021] [Accepted: 12/04/2021] [Indexed: 06/14/2023]
Abstract
The toxicological information of chlorinated polycyclic aromatic hydrocarbons (Cl-PAHs), as derivatives of PAHs, is still relatively lacking. In this study, a combination of transcriptomics and metabolomics approach was adopted to explore the changes in toxicity to human L02 hepatocytes after chlorination of benzo[a]pyrene (B[a]P) at 6 position. In general, 6-Cl-B[a]P produced a stronger toxicity to human hepatic cells than did parent B[a]P. When exposure concentrations were 5 and 50 nM, 6-Cl-B[a]P caused a weaker transcriptomic perturbation relative to B[a]P, whereas a stronger metabolomic perturbation, a stronger oxidative stress and a stronger inhibition effect on cell viability were caused by 6-Cl-B[a]P than did parent B[a]P. Pathway enrichment analysis indicated that 6-Cl-B[a]P produced a more widely perturbation to metabolic pathways than did B[a]P. Although they both significantly impaired the function of mitochondrial electron transport chain (ETC), the exact mechanism is different. B[a]P suppressed the expression of 20 genes regulating mitochondrial ETC mainly via AhR activation. However, 6-Cl-B[a]P produced a stronger inhibition on the activities of complexes I and V than did B[a]P. Meanwhile, 6-Cl-B[a]P also exhibited a stronger inhibition effect on mitochondrial β oxidation of fatty acid. Furthermore, 6-Cl-B[a]P and B[a]P both significantly disturbed the nucleotide metabolism, glycerophospholipid metabolism and amino acid metabolism in L02 cells.
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Affiliation(s)
- Yun Luo
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Baoqin Zhang
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Ningbo Geng
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Shuai Sun
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoyao Song
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Jiping Chen
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Haijun Zhang
- CAS Key Laboratory of Separation Sciences for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China.
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13
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Javidnia S, Cranwell S, Mueller SH, Selman C, Tullet JM, Kuchenbaecker K, Alic N. Mendelian randomization analyses implicate biogenesis of translation machinery in human aging. Genome Res 2022; 32:258-265. [PMID: 35078808 PMCID: PMC8805714 DOI: 10.1101/gr.275636.121] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 12/15/2021] [Indexed: 11/25/2022]
Abstract
Reduced provision of protein translation machinery promotes healthy aging in a number of animal models. In humans, however, inborn impairments in translation machinery are a known cause of several developmental disorders, collectively termed ribosomopathies. Here, we use casual inference approaches in genetic epidemiology to investigate whether adult, tissue-specific biogenesis of translation machinery drives human aging. We assess naturally occurring variation in the expression of genes encoding subunits specific to the two RNA polymerases (Pols) that transcribe ribosomal and transfer RNAs, namely Pol I and III, and the variation in expression of ribosomal protein (RP) genes, using Mendelian randomization. We find each causally associated with human longevity (β = −0.15 ± 0.047, P = 9.6 × 10−4, q = 0.015; β = −0.13 ± 0.040, P = 1.4 × 10−3, q = 0.023; β = −0.048 ± 0.016, P = 3.5 × 10−3, q = 0.056, respectively), and this does not appear to be mediated by altered susceptibility to a single disease. We find that reduced expression of Pol III, RPs, or Pol I promotes longevity from different organs, namely visceral adipose, liver, and skeletal muscle, echoing the tissue specificity of ribosomopathies. Our study shows the utility of leveraging genetic variation in expression to elucidate how essential cellular processes impact human aging. The findings extend the evolutionary conservation of protein synthesis as a critical process that drives animal aging to include humans.
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Kessler AC, Maraia RJ. The nuclear and cytoplasmic activities of RNA polymerase III, and an evolving transcriptome for surveillance. Nucleic Acids Res 2021; 49:12017-12034. [PMID: 34850129 PMCID: PMC8643620 DOI: 10.1093/nar/gkab1145] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 10/26/2021] [Accepted: 11/02/2021] [Indexed: 12/23/2022] Open
Abstract
A 1969 report that described biochemical and activity properties of the three eukaryotic RNA polymerases revealed Pol III as highly distinguishable, even before its transcripts were identified. Now known to be the most complex, Pol III contains several stably-associated subunits referred to as built-in transcription factors (BITFs) that enable highly efficient RNA synthesis by a unique termination-associated recycling process. In vertebrates, subunit RPC7(α/β) can be of two forms, encoded by POLR3G or POLR3GL, with differential activity. Here we review promoter-dependent transcription by Pol III as an evolutionary perspective of eukaryotic tRNA expression. Pol III also provides nonconventional functions reportedly by promoter-independent transcription, one of which is RNA synthesis from DNA 3'-ends during repair. Another is synthesis of 5'ppp-RNA signaling molecules from cytoplasmic viral DNA in a pathway of interferon activation that is dysfunctional in immunocompromised patients with mutations in Pol III subunits. These unconventional functions are also reviewed, including evidence that link them to the BITF subunits. We also review data on a fraction of the human Pol III transcriptome that evolved to include vault RNAs and snaRs with activities related to differentiation, and in innate immune and tumor surveillance. The Pol III of higher eukaryotes does considerably more than housekeeping.
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Affiliation(s)
- Alan C Kessler
- Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892 USA
| | - Richard J Maraia
- Division of Intramural Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892 USA
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15
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Bian M, Huang S, Yu D, Zhou Z. tRNA Metabolism and Lung Cancer: Beyond Translation. Front Mol Biosci 2021; 8:659388. [PMID: 34660690 PMCID: PMC8516113 DOI: 10.3389/fmolb.2021.659388] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 08/25/2021] [Indexed: 12/15/2022] Open
Abstract
Lung cancer, one of the most malignant tumors, has extremely high morbidity and mortality, posing a serious threat to global health. It is an urgent need to fully understand the pathogenesis of lung cancer and provide new ideas for its treatment. Interestingly, accumulating evidence has identified that transfer RNAs (tRNAs) and tRNA metabolism–associated enzymes not only participate in the protein translation but also play an important role in the occurrence and development of lung cancer. In this review, we summarize the different aspects of tRNA metabolism in lung cancer, such as tRNA transcription and mutation, tRNA molecules and derivatives, tRNA-modifying enzymes, and aminoacyl-tRNA synthetases (ARSs), aiming at a better understanding of the pathogenesis of lung cancer and providing new therapeutic strategies for it.
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Affiliation(s)
- Meng Bian
- Department of Chinese Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Shiqiong Huang
- Department of Pharmacy, The First Hospital of Changsha, Changsha, China
| | - Dongsheng Yu
- Department of Chinese Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Zheng Zhou
- Department of Chinese Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
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16
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Defective myelination in an RNA polymerase III mutant leukodystrophic mouse. Proc Natl Acad Sci U S A 2021; 118:2024378118. [PMID: 34583988 DOI: 10.1073/pnas.2024378118] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/25/2021] [Indexed: 01/06/2023] Open
Abstract
RNA polymerase (Pol) III synthesizes abundant short noncoding RNAs that have essential functions in protein synthesis, secretion, and other processes. Despite the ubiquitous functions of these RNAs, mutations in Pol III subunits cause Pol III-related leukodystrophy, an early-onset neurodegenerative disease. The basis of this neural sensitivity and the mechanisms of disease pathogenesis are unknown. Here we show that mice expressing pathogenic mutations in the largest Pol III subunit, Polr3a, specifically in Olig2-expressing cells, have impaired growth and developmental delay, deficits in cognitive, sensory, and fine sensorimotor function, and hypomyelination in multiple regions of the cerebrum and spinal cord. These phenotypes reflect a subset of clinical features seen in patients. In contrast, the gross motor defects and cerebellar hypomyelination that are common features of severely affected patients are absent in the mice, suggesting a relatively mild form of the disease in this conditional model. Our results show that disease pathogenesis in the mice involves defects that reduce both the number of mature myelinating oligodendrocytes and the ability of these cells to produce a myelin sheath of normal thickness. The findings suggest unique sensitivities of oligodendrogenesis and myelination to perturbations of Pol III transcription.
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17
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Kulaberoglu Y, Malik Y, Borland G, Selman C, Alic N, Tullet JMA. RNA Polymerase III, Ageing and Longevity. Front Genet 2021; 12:705122. [PMID: 34295356 PMCID: PMC8290157 DOI: 10.3389/fgene.2021.705122] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 06/14/2021] [Indexed: 11/13/2022] Open
Abstract
Transcription in eukaryotic cells is performed by three RNA polymerases. RNA polymerase I synthesises most rRNAs, whilst RNA polymerase II transcribes all mRNAs and many non-coding RNAs. The largest of the three polymerases is RNA polymerase III (Pol III) which transcribes a variety of short non-coding RNAs including tRNAs and the 5S rRNA, in addition to other small RNAs such as snRNAs, snoRNAs, SINEs, 7SL RNA, Y RNA, and U6 spilceosomal RNA. Pol III-mediated transcription is highly dynamic and regulated in response to changes in cell growth, cell proliferation and stress. Pol III-generated transcripts are involved in a wide variety of cellular processes, including translation, genome and transcriptome regulation and RNA processing, with Pol III dys-regulation implicated in diseases including leukodystrophy, Alzheimer's, Fragile X-syndrome and various cancers. More recently, Pol III was identified as an evolutionarily conserved determinant of organismal lifespan acting downstream of mTORC1. Pol III inhibition extends lifespan in yeast, worms and flies, and in worms and flies acts from the intestine and intestinal stem cells respectively to achieve this. Intriguingly, Pol III activation achieved through impairment of its master repressor, Maf1, has also been shown to promote longevity in model organisms, including mice. In this review we introduce the Pol III transcription apparatus and review the current understanding of RNA Pol III's role in ageing and lifespan in different model organisms. We then discuss the potential of Pol III as a therapeutic target to improve age-related health in humans.
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Affiliation(s)
- Yavuz Kulaberoglu
- Department of Genetics Evolution and Environment, Institute of Healthy Ageing, University College London, London, United Kingdom
| | - Yasir Malik
- Faculty of Natural Sciences, University of Kent, Canterbury, United Kingdom
| | - Gillian Borland
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Colin Selman
- Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
| | - Nazif Alic
- Department of Genetics Evolution and Environment, Institute of Healthy Ageing, University College London, London, United Kingdom.,Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, Glasgow, United Kingdom
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Roles of tRNA metabolism in aging and lifespan. Cell Death Dis 2021; 12:548. [PMID: 34039958 PMCID: PMC8154886 DOI: 10.1038/s41419-021-03838-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 12/17/2022]
Abstract
Transfer RNAs (tRNAs) mainly function as adapter molecules that decode messenger RNAs (mRNAs) during protein translation by delivering amino acids to the ribosome. Traditionally, tRNAs are considered as housekeepers without additional functions. Nevertheless, it has become apparent from biological research that tRNAs are involved in various physiological and pathological processes. Aging is a form of gradual decline in physiological function that ultimately leads to increased vulnerability to multiple chronic diseases and death. Interestingly, tRNA metabolism is closely associated with aging and lifespan. In this review, we summarize the emerging roles of tRNA-associated metabolism, such as tRNA transcription, tRNA molecules, tRNA modifications, tRNA aminoacylation, and tRNA derivatives, in aging and lifespan, aiming to provide new ideas for developing therapeutics and ultimately extending lifespan in humans.
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