1
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Valeeva LR, Abdulkina LR, Agabekian IA, Shakirov EV. Telomere biology and ribosome biogenesis: structural and functional interconnections. Biochem Cell Biol 2023; 101:394-409. [PMID: 36989538 DOI: 10.1139/bcb-2022-0383] [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] [Indexed: 03/31/2023] Open
Abstract
Telomeres are nucleoprotein structures that play a pivotal role in the protection and maintenance of eukaryotic chromosomes. Telomeres and the enzyme telomerase, which replenishes telomeric DNA lost during replication, are important factors necessary to ensure continued cell proliferation. Cell proliferation is also dependent on proper and efficient protein synthesis, which is carried out by ribosomes. Mutations in genes involved in either ribosome biogenesis or telomere biology result in cellular abnormalities and can cause human genetic diseases, defined as ribosomopathies and telomeropathies, respectively. Interestingly, recent discoveries indicate that many of the ribosome assembly and rRNA maturation factors have additional noncanonical functions in telomere biology. Similarly, several key proteins and enzymes involved in telomere biology, including telomerase, have unexpected roles in rRNA transcription and maturation. These observations point to an intriguing cross-talk mechanism potentially explaining the multiple pleiotropic symptoms of mutations in many causal genes identified in various telomeropathy and ribosomopathy diseases. In this review, we provide a brief summary of eukaryotic telomere and rDNA loci structures, highlight several universal features of rRNA and telomerase biogenesis, evaluate intriguing interconnections between telomere biology and ribosome assembly, and conclude with an assessment of overlapping features of human diseases of telomeropathies and ribosomopathies.
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Affiliation(s)
- Liia R Valeeva
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan 420008, Republic of Tatarstan, Russia
- Department of Biological Sciences, College of Science, Marshall University, Huntington, WV 25701, USA
| | - Liliia R Abdulkina
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan 420008, Republic of Tatarstan, Russia
| | - Inna A Agabekian
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan 420008, Republic of Tatarstan, Russia
| | - Eugene V Shakirov
- Department of Biological Sciences, College of Science, Marshall University, Huntington, WV 25701, USA
- Department of Biomedical Sciences, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV 25755, USA
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2
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Abstract
The p-arms of the five human acrocentric chromosomes bear nucleolar organizer regions (NORs) comprising ribosomal gene (rDNA) repeats that are organized in a homogeneous tandem array and transcribed in a telomere-to-centromere direction. Precursor ribosomal RNA transcripts are processed and assembled into ribosomal subunits, the nucleolus being the physical manifestation of this process. I review current understanding of nucleolar chromosome biology and describe current exploration into a role for the NOR chromosomal context. Full DNA sequences for acrocentric p-arms are now emerging, aided by the current revolution in long-read sequencing and genome assembly. Acrocentric p-arms vary from 10.1 to 16.7 Mb, accounting for ∼2.2% of the genome. Bordering rDNA arrays, distal junctions, and proximal junctions are shared among the p-arms, with distal junctions showing evidence of functionality. The remaining p-arm sequences comprise multiple satellite DNA classes and segmental duplications that facilitate recombination between heterologous chromosomes, which is likely also involved in Robertsonian translocations.
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Affiliation(s)
- Brian McStay
- Centre for Chromosome Biology, College of Science and Engineering, University of Galway, Galway, Ireland;
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3
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Harold C. All these screens that we've done: how functional genetic screens have informed our understanding of ribosome biogenesis. Biosci Rep 2023; 43:BSR20230631. [PMID: 37335083 PMCID: PMC10329186 DOI: 10.1042/bsr20230631] [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: 04/09/2023] [Revised: 06/08/2023] [Accepted: 06/19/2023] [Indexed: 06/21/2023] Open
Abstract
Ribosome biogenesis is the complex and essential process that ultimately leads to the synthesis of cellular proteins. Understanding each step of this essential process is imperative to increase our understanding of basic biology, but also more critically, to provide novel therapeutic avenues for genetic and developmental diseases such as ribosomopathies and cancers which can arise when this process is impaired. In recent years, significant advances in technology have made identifying and characterizing novel human regulators of ribosome biogenesis via high-content, high-throughput screens. Additionally, screening platforms have been used to discover novel therapeutics for cancer. These screens have uncovered a wealth of knowledge regarding novel proteins involved in human ribosome biogenesis, from the regulation of the transcription of the ribosomal RNA to global protein synthesis. Specifically, comparing the discovered proteins in these screens showed interesting connections between large ribosomal subunit (LSU) maturation factors and earlier steps in ribosome biogenesis, as well as overall nucleolar integrity. In this review, a discussion of the current standing of screens for human ribosome biogenesis factors through the lens of comparing the datasets and discussing the biological implications of the areas of overlap will be combined with a look toward other technologies and how they can be adapted to discover more factors involved in ribosome synthesis, and answer other outstanding questions in the field.
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Affiliation(s)
- Cecelia M. Harold
- Department of Genetics, Yale School of Medicine, New Haven, CT, U.S.A
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4
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Nucleolus and Nucleolar Stress: From Cell Fate Decision to Disease Development. Cells 2022; 11:cells11193017. [PMID: 36230979 PMCID: PMC9563748 DOI: 10.3390/cells11193017] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 09/19/2022] [Accepted: 09/22/2022] [Indexed: 11/30/2022] Open
Abstract
Besides the canonical function in ribosome biogenesis, there have been significant recent advances towards the fascinating roles of the nucleolus in stress response, cell destiny decision and disease progression. Nucleolar stress, an emerging concept describing aberrant nucleolar structure and function as a result of impaired rRNA synthesis and ribosome biogenesis under stress conditions, has been linked to a variety of signaling transductions, including but not limited to Mdm2-p53, NF-κB and HIF-1α pathways. Studies have uncovered that nucleolus is a stress sensor and signaling hub when cells encounter various stress conditions, such as nutrient deprivation, DNA damage and oxidative and thermal stress. Consequently, nucleolar stress plays a pivotal role in the determination of cell fate, such as apoptosis, senescence, autophagy and differentiation, in response to stress-induced damage. Nucleolar homeostasis has been involved in the pathogenesis of various chronic diseases, particularly tumorigenesis, neurodegenerative diseases and metabolic disorders. Mechanistic insights have revealed the indispensable role of nucleolus-initiated signaling in the progression of these diseases. Accordingly, the intervention of nucleolar stress may pave the path for developing novel therapies against these diseases. In this review, we systemically summarize recent findings linking the nucleolus to stress responses, signaling transduction and cell-fate decision, set the spotlight on the mechanisms by which nucleolar stress drives disease progression, and highlight the merit of the intervening nucleolus in disease treatment.
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Gál Z, Nieto B, Boukoura S, Rasmussen AV, Larsen DH. Treacle Sticks the Nucleolar Responses to DNA Damage Together. Front Cell Dev Biol 2022; 10:892006. [PMID: 35646927 PMCID: PMC9133508 DOI: 10.3389/fcell.2022.892006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 04/21/2022] [Indexed: 01/05/2023] Open
Abstract
The importance of chromatin environment for DNA repair has gained increasing recognition in recent years. The nucleolus is the largest sub-compartment within the nucleus: it has distinct biophysical properties, selective protein retention, and houses the specialized ribosomal RNA genes (collectively referred to as rDNA) with a unique chromatin composition. These genes have high transcriptional activity and a repetitive nature, making them susceptible to DNA damage and resulting in the highest frequency of rearrangements across the genome. A distinct DNA damage response (DDR) secures the fidelity of this genomic region, the so-called nucleolar DDR (n-DDR). The composition of the n-DDR reflects the characteristics of nucleolar chromatin with the nucleolar protein Treacle (also referred to as TCOF1) as a central coordinator retaining several well-characterized DDR proteins in the nucleolus. In this review, we bring together data on the structure of Treacle, its known functions in ribosome biogenesis, and its involvement in multiple branches of the n-DDR to discuss their interconnection. Furthermore, we discuss how the functions of Treacle in ribosome biogenesis and in the n-DDR may contribute to Treacher Collins Syndrome, a disease caused by mutations in Treacle. Finally, we outline outstanding questions that need to be addressed for a more comprehensive understanding of Treacle, the n-DDR, and the coordination of ribosome biogenesis and DNA repair.
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6
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Wang Z, Chen H, Wang P, Zhou M, Li G, Hu Z, Hu Q, Zhao J, Liu X, Wu L, Liang D. OUP accepted manuscript. Stem Cells Transl Med 2022; 11:297-309. [PMID: 35267023 PMCID: PMC8968737 DOI: 10.1093/stcltm/szab031] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 11/22/2021] [Indexed: 11/27/2022] Open
Abstract
Mesenchymal stem cells (MSCs) are a promising cellular vehicle for transferring anti-cancer factors to malignant tumors. Currently, a variety of anti-cancer agents, including the tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), have been loaded into MSCs derived from a range of sources through different engineering methods. These engineered MSCs exhibit enormous therapeutic potential for various cancers. To avoid the intrinsic defects of MSCs derived from tissues and the potential risk of viral vectors, TRAIL was site-specifically integrated into the ribosomal DNA (rDNA) locus of human-induced pluripotent stem cells (iPSCs) using a non-viral rDNA-targeting vector and transcription activator-like effector nickases (TALENickases). These genetically modified human iPSCs were differentiated into an unlimited number of homogeneous induced MSCs (TRAIL-iMSCs) that overexpressed TRAIL in both culture supernatants and cell lysates while maintaining MSC-like characteristics over continuous passages. We found that TRAIL-iMSCs significantly induced apoptosis in A375, A549, HepG2, and MCF-7 cells in vitro. After intravenous infusion, TRAIL-iMSCs had a prominent tissue tropism for A549 or MCF-7 xenografts and significantly inhibited tumor growth through the activation of apoptotic signaling pathways without obvious side effects in tumor-bearing mice models. Altogether, our results showed that TRAIL-iMSCs have strong anti-tumor effects in vitro and in vivo on a range of cancers. This study allows for the development of an unlimited number of therapeutic gene-targeted MSCs with stable quality and high homogeneity for cancer therapy, thus highlighting a universal and safe strategy for stem cell-based gene therapy with high potential for clinical applications.
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Affiliation(s)
- Zujia Wang
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, People’s Republic of China
| | - Hongting Chen
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, People’s Republic of China
| | - Peiyun Wang
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, People’s Republic of China
| | - Miaojin Zhou
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, People’s Republic of China
| | - Guangxu Li
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, People’s Republic of China
| | - Zhiqing Hu
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, People’s Republic of China
| | - Qian Hu
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, People’s Republic of China
| | - Junya Zhao
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, People’s Republic of China
| | - Xionghao Liu
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, People’s Republic of China
| | - Lingqian Wu
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, People’s Republic of China
- Corresponding authors: Lingqian Wu, MD, PhD, Professor, Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, Hunan 410078, People’s Republic of China. Tel: +86-731-84805252; Fax: +86-731-84478152;
| | - Desheng Liang
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan, People’s Republic of China
- Desheng Liang, MD, PhD, Professor, Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, 110 Xiangya Road, Changsha, Hunan 410078, People’s Republic of China. Tel: +86-731-84805252; Fax: +86-731-84478152;
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7
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Regulatory roles of nucleolus organizer region-derived long non-coding RNAs. Mamm Genome 2021; 33:402-411. [PMID: 34436664 DOI: 10.1007/s00335-021-09906-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Accepted: 08/20/2021] [Indexed: 12/13/2022]
Abstract
The nucleolus is the largest sub-nuclear domain, serving primarily as the place for ribosome biogenesis. A delicately regulated function of the nucleolus is vital to the cell not only for maintaining proper protein synthesis but is also tightly associated with responses to different types of cellular stresses. Recently, several long non-coding RNAs (lncRNAs) were found to be part of the regulatory network that modulate nucleolar functions. Several of these lncRNAs are encoded in the ribosomal DNA (rDNA) repeats or are transcribed from the genomic regions that are located near the nucleolus organizer regions (NORs). In this review, we first discuss the current understanding of the sequence of the NORs and variations between different NORs. We then focus on the NOR-derived lncRNAs in mammalian cells and their functions in rRNA transcription and the organization of nucleolar structure under different cellular conditions. The identification of these lncRNAs reveals great potential of the NORs in harboring novel genes involved in the regulation of nucleolar functions.
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8
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Xuan J, Gitareja K, Brajanovski N, Sanij E. Harnessing the Nucleolar DNA Damage Response in Cancer Therapy. Genes (Basel) 2021; 12:genes12081156. [PMID: 34440328 PMCID: PMC8393943 DOI: 10.3390/genes12081156] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2021] [Revised: 07/20/2021] [Accepted: 07/26/2021] [Indexed: 12/19/2022] Open
Abstract
The nucleoli are subdomains of the nucleus that form around actively transcribed ribosomal RNA (rRNA) genes. They serve as the site of rRNA synthesis and processing, and ribosome assembly. There are 400-600 copies of rRNA genes (rDNA) in human cells and their highly repetitive and transcribed nature poses a challenge for DNA repair and replication machineries. It is only in the last 7 years that the DNA damage response and processes of DNA repair at the rDNA repeats have been recognized to be unique and distinct from the classic response to DNA damage in the nucleoplasm. In the last decade, the nucleolus has also emerged as a central hub for coordinating responses to stress via sequestering tumor suppressors, DNA repair and cell cycle factors until they are required for their functional role in the nucleoplasm. In this review, we focus on features of the rDNA repeats that make them highly vulnerable to DNA damage and the mechanisms by which rDNA damage is repaired. We highlight the molecular consequences of rDNA damage including activation of the nucleolar DNA damage response, which is emerging as a unique response that can be exploited in anti-cancer therapy. In this review, we focus on CX-5461, a novel inhibitor of Pol I transcription that induces the nucleolar DNA damage response and is showing increasing promise in clinical investigations.
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Affiliation(s)
- Jiachen Xuan
- Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; (J.X.); (K.G.); (N.B.)
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC 3010, Australia
| | - Kezia Gitareja
- Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; (J.X.); (K.G.); (N.B.)
| | - Natalie Brajanovski
- Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; (J.X.); (K.G.); (N.B.)
| | - Elaine Sanij
- Peter MacCallum Cancer Centre, Melbourne, VIC 3000, Australia; (J.X.); (K.G.); (N.B.)
- Sir Peter MacCallum Department of Oncology, University of Melbourne, Melbourne, VIC 3010, Australia
- Department of Clinical Pathology, University of Melbourne, Melbourne, VIC 3010, Australia
- St Vincent’s Institute of Medical Research, Fitzroy, VIC 3065, Australia
- Department of Medicine -St Vincent’s Hospital, University of Melbourne, Melbourne, VIC 3010, Australia
- Correspondence: ; Tel.: +61-3-8559-5279
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9
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10
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Goffová I, Fajkus J. The rDNA Loci-Intersections of Replication, Transcription, and Repair Pathways. Int J Mol Sci 2021; 22:1302. [PMID: 33525595 PMCID: PMC7865372 DOI: 10.3390/ijms22031302] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 01/25/2021] [Accepted: 01/25/2021] [Indexed: 12/28/2022] Open
Abstract
Genes encoding ribosomal RNA (rDNA) are essential for cell survival and are particularly sensitive to factors leading to genomic instability. Their repetitive character makes them prone to inappropriate recombinational events arising from collision of transcriptional and replication machineries, resulting in unstable rDNA copy numbers. In this review, we summarize current knowledge on the structure and organization of rDNA, its role in sensing changes in the genome, and its linkage to aging. We also review recent findings on the main factors involved in chromatin assembly and DNA repair in the maintenance of rDNA stability in the model plants Arabidopsis thaliana and the moss Physcomitrella patens, providing a view across the plant evolutionary tree.
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Affiliation(s)
- Ivana Goffová
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, CZ-61137 Brno, Czech Republic;
- Chromatin Molecular Complexes, Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, CZ-62500 Brno, Czech Republic
| | - Jiří Fajkus
- Laboratory of Functional Genomics and Proteomics, National Centre for Biomolecular Research, Faculty of Science, Masaryk University, CZ-61137 Brno, Czech Republic;
- Chromatin Molecular Complexes, Mendel Centre for Plant Genomics and Proteomics, Central European Institute of Technology, Masaryk University, CZ-62500 Brno, Czech Republic
- Department of Cell Biology and Radiobiology, Institute of Biophysics of the Czech Academy of Sciences, CZ-61265 Brno, Czech Republic
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11
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Balzano E, Pelliccia F, Giunta S. Genome (in)stability at tandem repeats. Semin Cell Dev Biol 2020; 113:97-112. [PMID: 33109442 DOI: 10.1016/j.semcdb.2020.10.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 09/26/2020] [Accepted: 10/10/2020] [Indexed: 12/12/2022]
Abstract
Repeat sequences account for over half of the human genome and represent a significant source of variation that underlies physiological and pathological states. Yet, their study has been hindered due to limitations in short-reads sequencing technology and difficulties in assembly. A important category of repetitive DNA in the human genome is comprised of tandem repeats (TRs), where repetitive units are arranged in a head-to-tail pattern. Compared to other regions of the genome, TRs carry between 10 and 10,000 fold higher mutation rate. There are several mutagenic mechanisms that can give rise to this propensity toward instability, but their precise contribution remains speculative. Given the high degree of homology between these sequences and their arrangement in tandem, once damaged, TRs have an intrinsic propensity to undergo aberrant recombination with non-allelic exchange and generate harmful rearrangements that may undermine the stability of the entire genome. The dynamic mutagenesis at TRs has been found to underlie individual polymorphism associated with neurodegenerative and neuromuscular disorders, as well as complex genetic diseases like cancer and diabetes. Here, we review our current understanding of the surveillance and repair mechanisms operating within these regions, and we describe how alterations in these protective processes can readily trigger mutational signatures found at TRs, ultimately resulting in the pathological correlation between TRs instability and human diseases. Finally, we provide a viewpoint to counter the detrimental effects that TRs pose in light of their selection and conservation, as important drivers of human evolution.
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Affiliation(s)
- Elisa Balzano
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, 00185 Roma, Italy
| | - Franca Pelliccia
- Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, 00185 Roma, Italy
| | - Simona Giunta
- The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza Università di Roma, 00185 Roma, Italy.
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12
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Erath J, Djuranovic S, Djuranovic SP. Adaptation of Translational Machinery in Malaria Parasites to Accommodate Translation of Poly-Adenosine Stretches Throughout Its Life Cycle. Front Microbiol 2019; 10:2823. [PMID: 31866984 PMCID: PMC6908487 DOI: 10.3389/fmicb.2019.02823] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Accepted: 11/21/2019] [Indexed: 11/13/2022] Open
Abstract
Malaria is caused by unicellular apicomplexan parasites of the genus Plasmodium, which includes the major human parasite Plasmodium falciparum. The complex cycle of the malaria parasite in both mosquito and human hosts has been studied extensively. There is tight control of gene expression in each developmental stage, and at every level of gene synthesis: from RNA transcription, to its subsequent translation, and finally post-translational modifications of the resulting protein. Whole-genome sequencing of P. falciparum has laid the foundation for significant biological advances by revealing surprising genomic information. The P. falciparum genome is extremely AT-rich (∼80%), with a substantial portion of genes encoding intragenic polyadenosine (polyA) tracks being expressed throughout the entire parasite life cycle. In most eukaryotes, intragenic polyA runs act as negative regulators of gene expression. Recent studies have shown that translation of mRNAs containing 12 or more consecutive adenosines results in ribosomal stalling and frameshifting; activating mRNA surveillance mechanisms. In contrast, P. falciparum translational machinery can efficiently and accurately translate polyA tracks without activating mRNA surveillance pathways. This unique feature of P. falciparum raises interesting questions: (1) How is P. falciparum able to efficiently and correctly translate polyA track transcripts, and (2) What are the specifics of the translational machinery and mRNA surveillance mechanisms that separate P. falciparum from other organisms? In this review, we analyze possible evolutionary shifts in P. falciparum protein synthesis machinery that allow efficient translation of an AU rich-transcriptome. We focus on physiological and structural differences of P. falciparum stage specific ribosomes, ribosome-associated proteins, and changes in mRNA surveillance mechanisms throughout the complete parasite life cycle, with an emphasis on the mosquito and liver stages.
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Affiliation(s)
| | - Sergej Djuranovic
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, United States
| | - Slavica Pavlovic Djuranovic
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, United States
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13
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van Sluis M, Gailín MÓ, McCarter JGW, Mangan H, Grob A, McStay B. Human NORs, comprising rDNA arrays and functionally conserved distal elements, are located within dynamic chromosomal regions. Genes Dev 2019; 33:1688-1701. [PMID: 31727772 PMCID: PMC6942050 DOI: 10.1101/gad.331892.119] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 10/23/2019] [Indexed: 01/09/2023]
Abstract
In this study, van Sluis et al. investigated the role of chromosomal context in nuclear organizer regions (NORs)/ribosomal gene (rDNA) in nucleolar formation and function. The analyses combined sequence capture and long-read sequencing to characterize the regions distal to rDNA arrays (DJ) on isolated acrocentric chromosomes, and their findings provide direct evidence for exchanges between heterologous human acrocentric p-arms, and uncover extensive structural variation between chromosomes and among individuals. Human nucleolar organizer regions (NORs), containing ribosomal gene (rDNA) arrays, are located on the p-arms of acrocentric chromosomes (HSA13–15, 21, and 22). Absence of these p-arms from genome references has hampered research on nucleolar formation. Previously, we assembled a distal junction (DJ) DNA sequence contig that abuts rDNA arrays on their telomeric side, revealing that it is shared among the acrocentrics and impacts nucleolar organization. To facilitate inclusion into genome references, we describe sequencing the DJ from all acrocentrics, including three versions of HSA21, ∼3 Mb of novel sequence. This was achieved by exploiting monochromosomal somatic cell hybrids containing single human acrocentric chromosomes with NORs that retain functional potential. Analyses revealed remarkable DJ sequence and functional conservation among human acrocentrics. Exploring chimpanzee acrocentrics, we show that “DJ-like” sequences and abutting rDNA arrays are inverted as a unit in comparison to humans. Thus, rDNA arrays and linked DJs represent a conserved functional locus. We provide direct evidence for exchanges between heterologous human acrocentric p-arms, and uncover extensive structural variation between chromosomes and among individuals. These findings lead us to revaluate the molecular definition of NORs, identify novel genomic structural variation, and provide a rationale for the distinctive chromosomal organization of NORs.
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Affiliation(s)
- Marjolein van Sluis
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Michael Ó Gailín
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Joseph G W McCarter
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Hazel Mangan
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Alice Grob
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
| | - Brian McStay
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland Galway, Galway, Ireland
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14
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Liu X, Liu M, Wu L, Liang D. Gene Therapy for Hemophilia and Duchenne Muscular Dystrophy in China. Hum Gene Ther 2019; 29:146-150. [PMID: 29366352 DOI: 10.1089/hum.2017.213] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Gene therapy is a new technology that provides potential for curing monogenic diseases caused by mutations in a single gene. Hemophilia and Duchenne muscular dystrophy (DMD) are ideal target diseases of gene therapy. Important advances have been made in clinical trials, including studies of adeno-associated virus vectors in hemophilia and antisense in DMD. However, issues regarding the high doses of viral vectors required and limited delivery efficiency of antisense oligonucleotides have not yet been fully addressed. As an alternative strategy to classic gene addition, genome editing based on programmable nucleases has also shown promise to correct mutations in situ. This review describes the recent progress made by Chinese researchers in gene therapy for hemophilia and DMD.
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Affiliation(s)
- Xionghao Liu
- 1 School of Life Sciences, Central South University , Changsha, China
| | - Mujun Liu
- 1 School of Life Sciences, Central South University , Changsha, China
| | - Lingqian Wu
- 1 School of Life Sciences, Central South University , Changsha, China .,2 Hunan Jiahui Genetics Hospital , Changsha, China
| | - Desheng Liang
- 1 School of Life Sciences, Central South University , Changsha, China
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15
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Sun Q, Liu X, Wu Y, Niu W, Long P, Liu J, Lei M, Hu Y, Wu L, Li Z, Liang D. Ectopic expression of factor VIII in MSCs and hepatocytes derived from rDNA targeted hESCs. Clin Chim Acta 2018; 495:656-663. [PMID: 30096315 DOI: 10.1016/j.cca.2018.08.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 07/31/2018] [Accepted: 08/04/2018] [Indexed: 01/01/2023]
Abstract
Hemophilia A is an X-linked recessive bleeding disorder caused by FVIII gene deficiency, which may result in spontaneous joint hemorrhages or life-threatening bleeding. Currently, cell-based gene therapy via ex vivo transduction of transplantable cells with integrating gene-expressing vectors offers an attractive treatment for HA. In present study, we targeted an expression cassette of B-domain-deleted FVIII into the ribosomal DNA (rDNA) locus of human embryonic stem cells (hESCs) by transfection with a nonviral targeting plasmid pHrn. The targeted hESCs clone could be expanded and retained the main pluripotent properties of differentiation into three germ layers both in vitro and in vivo. Importantly, under defined induction conditions, the targeted hESCs could differentiated into functional mesenchymal stem cells (MSCs) and hepatocytes, as validated by relevant specific cell markers and functional examination. Tumorgenesis assay demonstrated that these cells are relatively safe for future applications. Analysis on gene expression revealed that exogenous FVIII mRNA and FVIII proteins were both present in differentiated MSCs and hepatocytes. These results indicated that through gene targeting at hESCs rDNA locus a persistent cell source of transplantable genetic-modified cells can be accomplished for HA therapy.
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Affiliation(s)
- Qianru Sun
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410078, China
| | - Xionghao Liu
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410078, China
| | - Yong Wu
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410078, China
| | - Wenbin Niu
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410078, China
| | - Panpan Long
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410078, China
| | - Jing Liu
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410078, China
| | - Ming Lei
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410078, China
| | - Youjin Hu
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410078, China
| | - Lingqian Wu
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410078, China
| | - Zhuo Li
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410078, China..
| | - Desheng Liang
- Center for Medical Genetics, School of Life Sciences, Central South University, Changsha, Hunan 410078, China..
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16
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Robicheau BM, Susko E, Harrigan AM, Snyder M. Ribosomal RNA Genes Contribute to the Formation of Pseudogenes and Junk DNA in the Human Genome. Genome Biol Evol 2018; 9:380-397. [PMID: 28204512 PMCID: PMC5381670 DOI: 10.1093/gbe/evw307] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/30/2016] [Indexed: 12/20/2022] Open
Abstract
Approximately 35% of the human genome can be identified as sequence devoid of a selected-effect function, and not derived from transposable elements or repeated sequences. We provide evidence supporting a known origin for a fraction of this sequence. We show that: 1) highly degraded, but near full length, ribosomal DNA (rDNA) units, including both 45S and Intergenic Spacer (IGS), can be found at multiple sites in the human genome on chromosomes without rDNA arrays, 2) that these rDNA sequences have a propensity for being centromere proximal, and 3) that sequence at all human functional rDNA array ends is divergent from canonical rDNA to the point that it is pseudogenic. We also show that small sequence strings of rDNA (from 45S + IGS) can be found distributed throughout the genome and are identifiable as an “rDNA-like signal”, representing 0.26% of the q-arm of HSA21 and ∼2% of the total sequence of other regions tested. The size of sequence strings found in the rDNA-like signal intergrade into the size of sequence strings that make up the full-length degrading rDNA units found scattered throughout the genome. We conclude that the displaced and degrading rDNA sequences are likely of a similar origin but represent different stages in their evolution towards random sequence. Collectively, our data suggests that over vast evolutionary time, rDNA arrays contribute to the production of junk DNA. The concept that the production of rDNA pseudogenes is a by-product of concerted evolution represents a previously under-appreciated process; we demonstrate here its importance.
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Affiliation(s)
- Brent M Robicheau
- Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada
| | - Edward Susko
- Center for Comparative Genomics and Evolutionary Bioinformatics, Department of Mathematics and Statistics, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Amye M Harrigan
- Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada
| | - Marlene Snyder
- Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada
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17
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Liu B, Chen F, Wu Y, Wang X, Feng M, Li Z, Zhou M, Wang Y, Wu L, Liu X, Liang D. Enhanced tumor growth inhibition by mesenchymal stem cells derived from iPSCs with targeted integration of interleukin24 into rDNA loci. Oncotarget 2018; 8:40791-40803. [PMID: 28388559 PMCID: PMC5522332 DOI: 10.18632/oncotarget.16584] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 03/13/2017] [Indexed: 12/16/2022] Open
Abstract
Induced pluripotent stem cells (iPSCs) are a promising source of mesenchymal stem cells (MSCs) for clinical applications. In this study, we transformed human iPSCs using a non-viral vector carrying the IL24 transgene pHrn-IL24. PCR and southern blotting confirmed IL24 integration into the rDNA loci in four of 68 iPSC clones. We then differentiated a high expressing IL24-iPSC clone into MSCs (IL24-iMSCs) that showed higher expression of IL24 in culture supernatants and in cell lysates than control iMSCs. IL24-iMSCs efficiently differentiated into osteoblasts, chondrocytes and adipocytes. Functionally, IL24-iMSCs induced in vitro apoptosis in B16-F10 melanoma cells more efficiently than control iMSCs when co-cultured in Transwell assays. In vivo tumor xenograft studies in mice demonstrated that IL24-iMSCs inhibited melanoma growth more than control iMSCs did. Immunofluorescence and histochemical analysis showed larger necrotic areas and cell nuclear aggregation in tumors with IL24-iMSCs than control iMSCs, indicating that IL24-iMSCs inhibited tumor growth by inducing apoptosis. These findings demonstrate efficient transformation of iPSCs through gene targeting with non-viral vectors into a rDNA locus. The ability of these genetically modified MSCs to inhibit in vivo melanoma growth is suggestive of the clinical potential of autologous cell therapy in cancer.
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Affiliation(s)
- Bo Liu
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Fei Chen
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Yong Wu
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Xiaolin Wang
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Mai Feng
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Zhuo Li
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Miaojin Zhou
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Yanchi Wang
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Lingqian Wu
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Xionghao Liu
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
| | - Desheng Liang
- The State Key Laboratory of Medical Genetics and School of Life Sciences, Central South University, Changsha, China
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18
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Abstract
Ribosome biogenesis is a complex and highly energy-demanding process that requires the concerted action of all three nuclear RNA polymerases (Pol I-III) in eukaryotes. The three largest ribosomal RNAs (rRNAs) originate from a precursor transcript (pre-rRNA) that is encoded by multicopy genes located in the nucleolus. Transcription of these rRNA genes (rDNA) by Pol I is the key regulation step in ribosome production and is tightly controlled by an intricate network of signaling pathways and epigenetic mechanisms. In this article, we give an overview of the composition of the basal Pol I machinery and rDNA chromatin. We discuss rRNA gene regulation in response to environmental signals and developmental cues and focus on perturbations occurring in diseases linked to either excessive or limited rRNA levels. Finally, we discuss the emerging view that rDNA integrity and activity may be involved in the aging process.
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Affiliation(s)
- Samim Sharifi
- Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich Schiller University, 07745 Jena, Germany; , .,Leibniz-Institute on Aging-Fritz Lipmann Institute, 07745 Jena, Germany
| | - Holger Bierhoff
- Institute of Biochemistry and Biophysics, Center for Molecular Biomedicine, Friedrich Schiller University, 07745 Jena, Germany; , .,Leibniz-Institute on Aging-Fritz Lipmann Institute, 07745 Jena, Germany
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19
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Feng M, Liu C, Xia Y, Liu B, Zhou M, Li Z, Sun Q, Hu Z, Wang Y, Wu L, Liu X, Liang D. Restoration of SMN expression in mesenchymal stem cells derived from gene-targeted patient-specific iPSCs. J Mol Histol 2017; 49:27-37. [DOI: 10.1007/s10735-017-9744-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 11/23/2017] [Indexed: 12/11/2022]
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20
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Zhu P, Duan AQ, Deng TX, Lu XR, Ma XY, Liang SS, Pang CY, Liang XW. Generation of buffalo mammary epithelial cells with targeted knockout of 18s rDNA by a CRISPR/Cas9 adenovirus system. BIOTECHNOL BIOPROC E 2017. [DOI: 10.1007/s12257-017-0094-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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21
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A role for Tau protein in maintaining ribosomal DNA stability and cytidine deaminase-deficient cell survival. Nat Commun 2017; 8:693. [PMID: 28947735 PMCID: PMC5612969 DOI: 10.1038/s41467-017-00633-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 07/14/2017] [Indexed: 12/20/2022] Open
Abstract
Cells from Bloom’s syndrome patients display genome instability due to a defective BLM and the downregulation of cytidine deaminase. Here, we use a genome-wide RNAi-synthetic lethal screen and transcriptomic profiling to identify genes enabling BLM-deficient and/or cytidine deaminase-deficient cells to tolerate constitutive DNA damage and replication stress. We found a synthetic lethal interaction between cytidine deaminase and microtubule-associated protein Tau deficiencies. Tau is overexpressed in cytidine deaminase-deficient cells, and its depletion worsens genome instability, compromising cell survival. Tau is recruited, along with upstream-binding factor, to ribosomal DNA loci. Tau downregulation decreases upstream binding factor recruitment, ribosomal RNA synthesis, ribonucleotide levels, and affects ribosomal DNA stability, leading to the formation of a new subclass of human ribosomal ultrafine anaphase bridges. We describe here Tau functions in maintaining survival of cytidine deaminase-deficient cells, and ribosomal DNA transcription and stability. Moreover, our findings for cancer tissues presenting concomitant cytidine deaminase underexpression and Tau upregulation open up new possibilities for anti-cancer treatment. Cytidine deaminase (CDA) deficiency leads to genome instability. Here the authors find a synthetic lethal interaction between CDA and the microtubule-associated protein Tau deficiencies, and report that Tau depletion affects rRNA synthesis, ribonucleotide pool balance, and rDNA stability.
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22
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Kobayashi T, Sasaki M. Ribosomal DNA stability is supported by many 'buffer genes'-introduction to the Yeast rDNA Stability Database. FEMS Yeast Res 2017; 17:fox001. [PMID: 28087673 DOI: 10.1093/femsyr/fox001] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/04/2017] [Indexed: 12/27/2022] Open
Abstract
The ribosomal RNA gene (rDNA) is the most abundant gene in yeast and other eukaryotic organisms. Due to its heavy transcription, repetitive structure and programmed replication fork pauses, the rDNA is one of the most unstable regions in the genome. Thus, the rDNA is the best region to study the mechanisms responsible for maintaining genome integrity. Recently, we screened a library of ∼4800 budding yeast gene knockout strains to identify mutants defective in the maintenance of rDNA stability. The results of this screen are summarized in the Yeast rDNA Stability (YRS) Database, in which the stability and copy number of rDNA in each mutant are presented. From this screen, we identified ∼700 genes that may contribute to the maintenance of rDNA stability. In addition, ∼50 mutants had abnormally high or low rDNA copy numbers. Moreover, some mutants with unstable rDNA displayed abnormalities in another chromosome. In this review, we introduce the YRS Database and discuss the roles of newly identified genes that contribute to rDNA maintenance and genome integrity.
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23
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Locati MD, Pagano JFB, Girard G, Ensink WA, van Olst M, van Leeuwen S, Nehrdich U, Spaink HP, Rauwerda H, Jonker MJ, Dekker RJ, Breit TM. Expression of distinct maternal and somatic 5.8S, 18S, and 28S rRNA types during zebrafish development. RNA (NEW YORK, N.Y.) 2017; 23:1188-1199. [PMID: 28500251 PMCID: PMC5513064 DOI: 10.1261/rna.061515.117] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 05/09/2017] [Indexed: 05/27/2023]
Abstract
There is mounting evidence that the ribosome is not a static translation machinery, but a cell-specific, adaptive system. Ribosomal variations have mostly been studied at the protein level, even though the essential transcriptional functions are primarily performed by rRNAs. At the RNA level, oocyte-specific 5S rRNAs are long known for Xenopus. Recently, we described for zebrafish a similar system in which the sole maternal-type 5S rRNA present in eggs is replaced completely during embryonic development by a somatic-type. Here, we report the discovery of an analogous system for the 45S rDNA elements: 5.8S, 18S, and 28S. The maternal-type 5.8S, 18S, and 28S rRNA sequences differ substantially from those of the somatic-type, plus the maternal-type rRNAs are also replaced by the somatic-type rRNAs during embryogenesis. We discuss the structural and functional implications of the observed sequence differences with respect to the translational functions of the 5.8S, 18S, and 28S rRNA elements. Finally, in silico evidence suggests that expansion segments (ES) in 18S rRNA, previously implicated in ribosome-mRNA interaction, may have a preference for interacting with specific mRNA genes. Taken together, our findings indicate that two distinct types of ribosomes exist in zebrafish during development, each likely conducting the translation machinery in a unique way.
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MESH Headings
- Animals
- Base Pairing
- Base Sequence
- DNA, Ribosomal/genetics
- Embryo, Nonmammalian/cytology
- Embryo, Nonmammalian/metabolism
- Nucleic Acid Conformation
- RNA Processing, Post-Transcriptional
- RNA, Ribosomal, 18S/genetics
- RNA, Ribosomal, 18S/metabolism
- RNA, Ribosomal, 28S/genetics
- RNA, Ribosomal, 28S/metabolism
- RNA, Ribosomal, 5.8S/genetics
- RNA, Ribosomal, 5.8S/metabolism
- Ribosomes/metabolism
- Sequence Alignment
- Zebrafish/genetics
- Zebrafish/growth & development
- Zebrafish/metabolism
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Affiliation(s)
- Mauro D Locati
- RNA Biology and Applied Bioinformatics Research Group, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam 1090 GE, the Netherlands
| | - Johanna F B Pagano
- RNA Biology and Applied Bioinformatics Research Group, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam 1090 GE, the Netherlands
| | - Geneviève Girard
- RNA Biology and Applied Bioinformatics Research Group, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam 1090 GE, the Netherlands
| | - Wim A Ensink
- RNA Biology and Applied Bioinformatics Research Group, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam 1090 GE, the Netherlands
| | - Marina van Olst
- RNA Biology and Applied Bioinformatics Research Group, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam 1090 GE, the Netherlands
| | - Selina van Leeuwen
- RNA Biology and Applied Bioinformatics Research Group, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam 1090 GE, the Netherlands
| | - Ulrike Nehrdich
- Department of Molecular Cell Biology, Institute of Biology, Leiden University, Gorlaeus Laboratories-Cell Observatorium, Leiden 2333 CE, the Netherlands
| | - Herman P Spaink
- Department of Molecular Cell Biology, Institute of Biology, Leiden University, Gorlaeus Laboratories-Cell Observatorium, Leiden 2333 CE, the Netherlands
| | - Han Rauwerda
- RNA Biology and Applied Bioinformatics Research Group, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam 1090 GE, the Netherlands
| | - Martijs J Jonker
- RNA Biology and Applied Bioinformatics Research Group, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam 1090 GE, the Netherlands
| | - Rob J Dekker
- RNA Biology and Applied Bioinformatics Research Group, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam 1090 GE, the Netherlands
| | - Timo M Breit
- RNA Biology and Applied Bioinformatics Research Group, Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam 1090 GE, the Netherlands
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24
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Saad H, Cobb JA. A decade of understanding spatio-temporal regulation of DNA repair by the nuclear architecture. Biochem Cell Biol 2016; 94:433-440. [DOI: 10.1139/bcb-2016-0085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The nucleus is a hub for gene expression and is a highly organized entity. The nucleoplasm is heterogeneous, owing to the preferential localization of specific metabolic factors, which lead to the definition of nuclear compartments or bodies. The genome is organized into chromosome territories, as well as heterochromatin and euchromatin domains. Recent observations have indicated that nuclear organization is important for maintaining genomic stability. For example, nuclear organization has been implicated in stabilizing damaged DNA, repair-pathway choice, and in preventing chromosomal rearrangements. Over the past decade, several studies have revealed that dynamic changes in the nuclear architecture are important during double-strand break repair. Stemming from work in yeast, relocation of a damaged site prior to repair appears to be at least partially conserved in multicellular eukaryotes. In this review, we will discuss genome and nucleoplasm architecture, particularly the importance of the nuclear periphery in genome stability. We will also discuss how the site of relocation regulates repair-pathway choice.
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Affiliation(s)
- Hicham Saad
- Southern Alberta Cancer Research Institute, Departments of Biochemistry & Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine; University of Calgary; 3330 Hospital Drive N.W., Calgary, AB T2N 4N1, Canada
- Southern Alberta Cancer Research Institute, Departments of Biochemistry & Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine; University of Calgary; 3330 Hospital Drive N.W., Calgary, AB T2N 4N1, Canada
| | - Jennifer A. Cobb
- Southern Alberta Cancer Research Institute, Departments of Biochemistry & Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine; University of Calgary; 3330 Hospital Drive N.W., Calgary, AB T2N 4N1, Canada
- Southern Alberta Cancer Research Institute, Departments of Biochemistry & Molecular Biology and Oncology, Robson DNA Science Centre, Arnie Charbonneau Cancer Institute, Cumming School of Medicine; University of Calgary; 3330 Hospital Drive N.W., Calgary, AB T2N 4N1, Canada
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25
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Abstract
Nucleoli form around tandem arrays of a ribosomal gene repeat, termed nucleolar organizer regions (NORs). During metaphase, active NORs adopt a characteristic undercondensed morphology. Recent evidence indicates that the HMG-box-containing DNA-binding protein UBF (upstream binding factor) is directly responsible for this morphology and provides a mitotic bookmark to ensure rapid nucleolar formation beginning in telophase in human cells. This is likely to be a widely employed strategy, as UBF is present throughout metazoans. In higher eukaryotes, NORs are typically located within regions of chromosomes that form perinucleolar heterochromatin during interphase. Typically, the genomic architecture of NORs and the chromosomal regions within which they lie is very poorly described, yet recent evidence points to a role for context in their function. In Arabidopsis, NOR silencing appears to be controlled by sequences outside the rDNA (ribosomal DNA) array. Translocations reveal a role for context in the expression of the NOR on the X chromosome in Drosophila Recent work has begun on characterizing the genomic architecture of human NORs. A role for distal sequences located in perinucleolar heterochromatin has been inferred, as they exhibit a complex transcriptionally active chromatin structure. Links between rDNA genomic stability and aging in Saccharomyces cerevisiae are now well established, and indications are emerging that this is important in aging and replicative senescence in higher eukaryotes. This, combined with the fact that rDNA arrays are recombinational hot spots in cancer cells, has focused attention on DNA damage responses in NORs. The introduction of DNA double-strand breaks into rDNA arrays leads to a dramatic reorganization of nucleolar structure. Damaged rDNA repeats move from the nucleolar interior to form caps at the nucleolar periphery, presumably to facilitate repair, suggesting that the chromosomal context of human NORs contributes to their genomic stability. The inclusion of NORs and their surrounding chromosomal environments in future genome drafts now becomes a priority.
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Affiliation(s)
- Brian McStay
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland, Galway, Ireland
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26
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Warmerdam DO, van den Berg J, Medema RH. Breaks in the 45S rDNA Lead to Recombination-Mediated Loss of Repeats. Cell Rep 2016; 14:2519-27. [PMID: 26972008 DOI: 10.1016/j.celrep.2016.02.048] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 01/11/2016] [Accepted: 02/07/2016] [Indexed: 11/29/2022] Open
Abstract
rDNA repeats constitute the most heavily transcribed region in the human genome. Tumors frequently display elevated levels of recombination in rDNA, indicating that the repeats are a liability to the genomic integrity of a cell. However, little is known about how cells deal with DNA double-stranded breaks in rDNA. Using selective endonucleases, we show that human cells are highly sensitive to breaks in 45S but not the 5S rDNA repeats. We find that homologous recombination inhibits repair of breaks in 45S rDNA, and this results in repeat loss. We identify the structural maintenance of chromosomes protein 5 (SMC5) as contributing to recombination-mediated repair of rDNA breaks. Together, our data demonstrate that SMC5-mediated recombination can lead to error-prone repair of 45S rDNA repeats, resulting in their loss and thereby reducing cellular viability.
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Affiliation(s)
- Daniël O Warmerdam
- Division of Cell Biology I, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands.
| | - Jeroen van den Berg
- Division of Cell Biology I, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands
| | - René H Medema
- Division of Cell Biology I, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, the Netherlands.
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27
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Saka K, Takahashi A, Sasaki M, Kobayashi T. More than 10% of yeast genes are related to genome stability and influence cellular senescence via rDNA maintenance. Nucleic Acids Res 2016; 44:4211-21. [PMID: 26912831 PMCID: PMC4872092 DOI: 10.1093/nar/gkw110] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 02/12/2016] [Indexed: 12/26/2022] Open
Abstract
Genome instability triggers cellular senescence and is a common cause of cancer. The ribosomal RNA genes (rDNA), due to their repetitive structure, form a fragile site with frequent rearrangements. To identify eukaryotic factors that connect reduced genome stability to senescence we screened 4,876 strains of a Saccharomyces cerevisiae deletion library for aberrant rDNA and found 708 genes that contribute to its upkeep. 28 mutants caused abnormalities in non-rDNA chromosomes and among them 12 mutants have abnormalities both in rDNA and in non-rDNA chromosomes. Many mutated genes have not previously been implicated with genome maintenance nor their homologues with tumorigenesis in mammals. The link between rDNA state and senescence was broken after deletion of factors related with DNA polymerase ϵ. These mutations also suppressed the short lifespan phenotype of a sir2 mutant, suggesting a model in which molecular events at the heart of the replication fork induce abnormal rDNA recombination and are responsible for the emergence of an aging signal.
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Affiliation(s)
- Kimiko Saka
- National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540 Japan
| | - Akihiro Takahashi
- National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540 Japan Sokendai, 1111 Yata, Mishima, Shizuoka 411-8540 Japan
| | - Mariko Sasaki
- National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540 Japan Laboratory of Genome Regeneration, Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Takehiko Kobayashi
- National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540 Japan Sokendai, 1111 Yata, Mishima, Shizuoka 411-8540 Japan Laboratory of Genome Regeneration, Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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28
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Tchurikov NA, Fedoseeva DM, Sosin DV, Snezhkina AV, Melnikova NV, Kudryavtseva AV, Kravatsky YV, Kretova OV. Hot spots of DNA double-strand breaks and genomic contacts of human rDNA units are involved in epigenetic regulation. J Mol Cell Biol 2014; 7:366-82. [PMID: 25280477 PMCID: PMC4524424 DOI: 10.1093/jmcb/mju038] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 08/23/2014] [Indexed: 12/25/2022] Open
Abstract
DNA double-strand breaks (DSBs) are involved in many cellular mechanisms, including replication, transcription, and genome rearrangements. The recent observation that hot spots of DSBs in human chromosomes delimit DNA domains that possess coordinately expressed genes suggests a strong relationship between the organization of transcription patterns and hot spots of DSBs. In this study, we performed mapping of hot spots of DSBs in a human 43-kb ribosomal DNA (rDNA) repeated unit. We observed that rDNA units corresponded to the most fragile sites in human chromosomes and that these units possessed at least nine specific regions containing clusters of extremely frequently occurring DSBs, which were located exclusively in non-coding intergenic spacer (IGS) regions. The hot spots of DSBs corresponded to only a specific subset of DNase-hypersensitive sites, and coincided with CTCF, PARP1, and HNRNPA2B1 binding sites, and H3K4me3 marks. Our rDNA-4C data indicate that the regions of IGS containing the hot spots of DSBs often form contacts with specific regions in different chromosomes, including the pericentromeric regions, as well as regions that are characterized by H3K27ac and H3K4me3 marks, CTCF binding sites, ChIA-PET and RIP signals, and high levels of DSBs. The data suggest a strong link between chromosome breakage and several different mechanisms of epigenetic regulation of gene expression.
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Affiliation(s)
- Nickolai A Tchurikov
- Department of Epigenetic Mechanisms of Gene Expression Regulation, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
| | - Daria M Fedoseeva
- Department of Epigenetic Mechanisms of Gene Expression Regulation, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
| | - Dmitri V Sosin
- Department of Epigenetic Mechanisms of Gene Expression Regulation, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
| | - Anastasia V Snezhkina
- Group of Postgenomic Studies, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
| | - Nataliya V Melnikova
- Group of Postgenomic Studies, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
| | - Anna V Kudryavtseva
- Group of Postgenomic Studies, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
| | - Yuri V Kravatsky
- Laboratory of DNA-Protein Interactions, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
| | - Olga V Kretova
- Department of Epigenetic Mechanisms of Gene Expression Regulation, Engelhardt Institute of Molecular Biology, Moscow 119334, Russia
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KOBAYASHI T. Ribosomal RNA gene repeats, their stability and cellular senescence. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2014; 90:119-29. [PMID: 24727936 PMCID: PMC4055705 DOI: 10.2183/pjab.90.119] [Citation(s) in RCA: 115] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Accepted: 01/08/2014] [Indexed: 05/19/2023]
Abstract
The ribosomal RNA gene (rDNA) repeats form a historically well-researched region in the chromosome. Their highly repetitive structure can be identified easily which has enabled studies on DNA replication, recombination, and transcription. The region is one of the most unstable regions in the genome because of deleterious recombination among the repeats. The ribosomal RNA gene repeats use a unique gene amplification system to restore the copy number after this has been reduced due to recombination. It has been shown that unstable features in the genome can accelerate cellular senescence that restricts the lifespan of a cell. Here, I will introduce a study by our group that shows how the stability of rDNA is maintained and affects lifespan. I propose that the ribosomal RNA gene repeats constitute a center from which the stability of the whole genome is regulated and the lifespan of the cell is controlled.
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Affiliation(s)
- Takehiko KOBAYASHI
- National Institute of Genetics, Division of Cytogenetics/Dept. of Genetics, The Graduate University for Advanced Studies, SOKENDAI, Shizuoka, Japan
- Correspondence should be addressed: T. Kobayashi, National Institute of Genetics, Division of Cytogenetics/Dept. of Genetics, The Graduate University for Advanced Studies, SOKENDAI, 1111 Yata, Mishima, Shizuoka 411-8540, Japan (e-mail: )
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Pérez-Ortín JE, Medina DA, Chávez S, Moreno J. What do you mean by transcription rate?: the conceptual difference between nascent transcription rate and mRNA synthesis rate is essential for the proper understanding of transcriptomic analyses. Bioessays 2013; 35:1056-62. [PMID: 24105897 DOI: 10.1002/bies.201300057] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
mRNA synthesis in all organisms is performed by RNA polymerases, which work as nanomachines on DNA templates. The rate at which their product is made is an important parameter in gene expression. Transcription rate encompasses two related, yet different, concepts: the nascent transcription rate, which measures the in situ mRNA production by RNA polymerase, and the rate of synthesis of mature mRNA, which measures the contribution of transcription to the mRNA concentration. Both parameters are useful for molecular biologists, but they are not interchangeable and they are expressed in different units. It is important to distinguish when and where each one should be used. We propose that for functional genomics the use of nascent transcription rates should be restricted to the evaluation of the transcriptional process itself, whereas mature mRNA synthesis rates should be employed to address the transcriptional input to mRNA concentration balance leading to variation of gene expression.
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Affiliation(s)
- José E Pérez-Ortín
- Departamento de Bioquímica y Biología Molecular, Universitat de València, Burjassot, Spain
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31
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Floutsakou I, Agrawal S, Nguyen TT, Seoighe C, Ganley ARD, McStay B. The shared genomic architecture of human nucleolar organizer regions. Genome Res 2013; 23:2003-12. [PMID: 23990606 PMCID: PMC3847771 DOI: 10.1101/gr.157941.113] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The short arms of the five acrocentric human chromosomes harbor sequences that direct the assembly and function of the nucleolus, one of the key functional domains of the nucleus, yet they are absent from the current human genome assembly. Here we describe the genomic architecture of these human nucleolar organizers. Sequences distal and proximal to ribosomal gene arrays are conserved among the acrocentric chromosomes, suggesting they are sites of frequent recombination. Although previously believed to be heterochromatic, characterization of these two flanking regions reveals that they share a complex genomic architecture similar to other euchromatic regions of the genome, but they have distinct genomic characteristics. Proximal sequences are almost entirely segmentally duplicated, similar to the regions bordering centromeres. In contrast, the distal sequence is predominantly unique to the acrocentric short arms and is dominated by a very large inverted repeat. We show that the distal element is localized to the periphery of the nucleolus, where it appears to anchor the ribosomal gene repeats. This, combined with its complex chromatin structure and transcriptional activity, suggests that this region is involved in nucleolar organization. Our results provide a platform for investigating the role of NORs in nucleolar formation and function, and open the door for determining the role of these regions in the well-known empirical association of nucleoli with pathology.
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Affiliation(s)
- Ioanna Floutsakou
- Centre for Chromosome Biology, School of Natural Sciences, National University of Ireland, Galway, Galway, Ireland
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32
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Nonviral gene targeting at rDNA locus of human mesenchymal stem cells. BIOMED RESEARCH INTERNATIONAL 2013; 2013:135189. [PMID: 23762822 PMCID: PMC3666425 DOI: 10.1155/2013/135189] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Accepted: 04/18/2013] [Indexed: 01/01/2023]
Abstract
Background. Genetic modification, such as the addition of exogenous genes to the MSC genome, is crucial to their use as cellular vehicles. Due to the risks associated with viral vectors such as insertional mutagenesis, the safer nonviral vectors have drawn a great deal of attention. Methods. VEGF, bFGF, vitamin C, and insulin-transferrin-selenium-X were supplemented in the MSC culture medium. The cells' proliferation and survival capacity was measured by MTT, determination of the cumulative number of cells, and a colony-forming efficiency assay. The plasmid pHr2-NL was constructed and nucleofected into MSCs. The recombinants were selected using G418 and characterized using PCR and Southern blotting. Results. BFGF is critical to MSC growth and it acted synergistically with vitamin C, VEGF, and ITS-X, causing the cells to expand significantly. The neomycin gene was targeted to the rDNA locus of human MSCs using a nonviral human ribosomal targeting vector. The recombinant MSCs retained multipotential differentiation capacity, typical levels of hMSC surface marker expression, and a normal karyotype, and none were tumorigenic in nude mice. Conclusions. Exogenous genes can be targeted to the rDNA locus of human MSCs while maintaining the characteristics of MSCs. This is the first nonviral gene targeting of hMSCs.
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Wei H, Zhou B, Zhang F, Tu Y, Hu Y, Zhang B, Zhai Q. Profiling and identification of small rDNA-derived RNAs and their potential biological functions. PLoS One 2013; 8:e56842. [PMID: 23418607 PMCID: PMC3572043 DOI: 10.1371/journal.pone.0056842] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 01/14/2013] [Indexed: 12/13/2022] Open
Abstract
Small non-coding RNAs constitute a large family of regulatory molecules with diverse functions. Notably, some small non-coding RNAs matched to rDNA have been identified as qiRNAs and small guide RNAs involved in various biological processes. However, a large number of small rDNA-derived RNAs (srRNAs) are usually neglected and yet to be investigated. We systematically investigated srRNAs using small RNA datasets generated by high-throughput sequencing, and found srRNAs are mainly mapped to rRNA coding regions in sense direction. The datasets from immunoprecipitation and high-throughput sequencing demonstrate that srRNAs are co-immunoprecipitated with Argonaute (AGO) proteins. Furthermore, the srRNA expression profile in mouse liver is affected by diabetes. Overexpression or inhibition of srRNAs in cultured cells shows that srRNAs are involved in various signaling pathways. This study presents a global view of srRNAs in total small RNA and AGO protein complex from different species, and demonstrates that srRNAs are correlated with diabetes, and involved in some biological processes. These findings provide new insights into srRNAs and their functions in various physiological and pathological processes.
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Affiliation(s)
- Haibin Wei
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People’s Republic of China
| | - Ben Zhou
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People’s Republic of China
| | - Fang Zhang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People’s Republic of China
| | - Yanyang Tu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People’s Republic of China
| | - Yanan Hu
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People’s Republic of China
| | - Baoguo Zhang
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People’s Republic of China
| | - Qiwei Zhai
- Key Laboratory of Nutrition and Metabolism, Institute for Nutritional Sciences, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, People’s Republic of China
- * E-mail:
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Bire S, Rouleux-Bonnin F. Transgene Site-Specific Integration: Problems and Solutions. SITE-DIRECTED INSERTION OF TRANSGENES 2013. [DOI: 10.1007/978-94-007-4531-5_1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Lisowski L, Lau A, Wang Z, Zhang Y, Zhang F, Grompe M, Kay MA. Ribosomal DNA integrating rAAV-rDNA vectors allow for stable transgene expression. Mol Ther 2012; 20:1912-23. [PMID: 22990671 DOI: 10.1038/mt.2012.164] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Although recombinant adeno-associated virus (rAAV) vectors are proving to be efficacious in clinical trials, the episomal character of the delivered transgene restricts their effectiveness to use in quiescent tissues, and may not provide lifelong expression. In contrast, integrating vectors enhance the risk of insertional mutagenesis. In an attempt to overcome both of these limitations, we created new rAAV-rDNA vectors, with an expression cassette flanked by ribosomal DNA (rDNA) sequences capable of homologous recombination into genomic rDNA. We show that after in vivo delivery the rAAV-rDNA vectors integrated into the genomic rDNA locus 8-13 times more frequently than control vectors, providing an estimate that 23-39% of the integrations were specific to the rDNA locus. Moreover, a rAAV-rDNA vector containing a human factor IX (hFIX) expression cassette resulted in sustained therapeutic levels of serum hFIX even after repeated manipulations to induce liver regeneration. Because of the relative safety of integration in the rDNA locus, these vectors expand the usage of rAAV for therapeutics requiring long-term gene transfer into dividing cells.
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Affiliation(s)
- Leszek Lisowski
- Stanford University, Departments of Pediatrics and Genetics, Stanford, California 94305-5164, USA
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Liu X, Wu Y, Li Z, Yang J, Xue J, Hu Y, Feng M, Niu W, Yang Q, Lei M, Xia J, Wu L, Liang D. Targeting of the human coagulation factor IX gene at rDNA locus of human embryonic stem cells. PLoS One 2012; 7:e37071. [PMID: 22615895 PMCID: PMC3353886 DOI: 10.1371/journal.pone.0037071] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2011] [Accepted: 04/12/2012] [Indexed: 01/15/2023] Open
Abstract
BACKGROUND Genetic modification is a prerequisite to realizing the full potential of human embryonic stem cells (hESCs) in human genetic research and regenerative medicine. Unfortunately, the random integration methods that have been the primary techniques used keep creating problems, and the primary alternative method, gene targeting, has been effective in manipulating mouse embryonic stem cells (mESCs) but poorly in hESCs. METHODOLOGY/PRINCIPAL FINDINGS Human ribosomal DNA (rDNA) repeats are clustered on the short arm of acrocentric chromosomes. They consist of approximately 400 copies of the 45S pre-RNA (rRNA) gene per haploid. In the present study, we targeted a physiological gene, human coagulation factor IX, into the rDNA locus of hESCs via homologous recombination. The relative gene targeting efficiency (>50%) and homologous recombination frequency (>10(-5)) were more than 10-fold higher than those of loci targeted in previous reports. Meanwhile, the targeted clones retained both a normal karyotype and the main characteristics of ES cells. The transgene was found to be stably and ectopically expressed in targeted hESCs. CONCLUSION/SIGNIFICANCE This is the first targeting of a human physiological gene at a defined locus on the hESC genome. Our findings indicate that the rDNA locus may serve as an ideal harbor for transgenes in hESCs.
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Affiliation(s)
- Xionghao Liu
- State Key Laboratory of Medical Genetics, Central South University, Changsha, Hunan, China
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Kobayashi T. Regulation of ribosomal RNA gene copy number and its role in modulating genome integrity and evolutionary adaptability in yeast. Cell Mol Life Sci 2011; 68:1395-403. [PMID: 21207101 PMCID: PMC3064901 DOI: 10.1007/s00018-010-0613-2] [Citation(s) in RCA: 151] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 12/03/2010] [Accepted: 12/10/2010] [Indexed: 12/31/2022]
Abstract
The genes encoding ribosomal RNA (rRNA) are the most abundant genes in the eukaryotic genome. They reside in tandem repetitive clusters, in some cases totaling hundreds of copies. Due to their repetitive structure and highly active transcription, the rRNA gene repeats are some of the most fragile sites in the chromosome. A unique gene amplification system compensates for loss of copies, thus maintaining copy number, albeit with some fluctuations. The unusual nature of rRNA gene repeats affects cellular functions such as senescence. In addition, we recently found that the repeat number determines sensitivity to DNA damage. In this review, I would like to introduce a new aspect of the rRNA gene repeat (called rDNA) as a center of maintenance of genome integrity and discuss its contribution to evolution.
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Affiliation(s)
- Takehiko Kobayashi
- Division of Cytogenetics, National Institute of Genetics/The Graduate University for Advanced Studies, SOKENDAI, 1111 Yata, Mishima, Shizuoka, Japan.
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Shamash J, Rienstein S, Wolf-Reznik H, Pras E, Dekel M, Litmanovitch T, Brengauz M, Goldman B, Yonath H, Dor J, Levron J, Aviram-Goldring A. Preimplantation genetic haplotyping a new application for diagnosis of translocation carrier's embryos- preliminary observations of two robertsonian translocation carrier families. J Assist Reprod Genet 2010; 28:77-83. [PMID: 20872064 DOI: 10.1007/s10815-010-9483-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2010] [Accepted: 09/13/2010] [Indexed: 11/29/2022] Open
Abstract
PURPOSE Preimplantation genetic diagnosis using fluorescence in-situ hybridization (PGD-FISH) is currently the most common reproductive solution for translocation carriers. However, this technique usually does not differentiate between embryos carrying the balanced form of the translocation and those carrying the homologous normal chromosomes. We developed a new application of preimplantation genetic haplotyping (PGH) that can identify and distinguish between all forms of the translocation status in cleavage stage embryos prior to implantation. METHODS Polymorphic markers were used to identify and differentiate between the alleles that carry the translocation and those that are the normal homologous chromosomes. RESULTS Embryos from two families of robertsonian translocation carriers were successfully analyzed using polymorphic markers haplotyping. CONCLUSIONS Our preliminary results indicate that the PGH is capable of distinguishing between normal, balanced and unbalanced translocation carrier embryos. This method will improve PGD and will enable translocation carriers to avoid transmission of the translocation and the associated medical complications to offspring.
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Affiliation(s)
- Jana Shamash
- Danek-Gertner Institute of Human Genetics, Chaim Sheba Medical Center, Tel Hashomer, Ramat Gan, 52621, Israel.
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Affiliation(s)
- Brian McStay
- Biomedical Research Center, Ninewells Hospital, University of Dundee, Dundee DD1 9SY, United Kingdom;
| | - Ingrid Grummt
- Molecular Biology of the Cell II, German Cancer Research Center, DKFZ-ZMBH Alliance, D-69120 Heidelberg, Germany;
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Pseudo-NORs: a novel model for studying nucleoli. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:2116-23. [PMID: 18687368 DOI: 10.1016/j.bbamcr.2008.07.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Revised: 07/08/2008] [Accepted: 07/08/2008] [Indexed: 11/21/2022]
Abstract
Nucleolar organiser regions (NORs) are comprised of tandem arrays of ribosomal gene (rDNA) repeats that are transcribed by RNA polymerase I (Pol I), ultimately resulting in formation of a nucleolus. Upstream binding factor (UBF), a DNA binding protein and component of the Pol I transcription machinery, binds extensively across the rDNA repeat in vivo. Pseudo-NORs are tandem arrays of a heterologous DNA sequence with high affinity for UBF introduced into human chromosomes. In this review we describe how analysis of pseudo-NORs has provided important insights into nucleolar formation. Pseudo-NORs mimic endogenous NORs in a number of important respects. On metaphase chromosomes both appear as secondary constrictions comprised of undercondensed chromatin. The transcriptional silence of pseudo-NORs provides a platform for studying the transcription independent recruitment of factors required for nucleolar formation by this specialised chromatin structure. During interphase, pseudo-NORs appear as distinct and novel sub-nuclear bodies. Analysis of these bodies and comparison to their endogenous counterpart has provided insights into nucleolar formation and structure.
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Efficient protein expression from the endogenous RNA polymerase I promoter using a human ribosomal DNA targeting vector. Biochem Biophys Res Commun 2008; 367:846-51. [DOI: 10.1016/j.bbrc.2008.01.018] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2007] [Accepted: 01/03/2008] [Indexed: 12/17/2022]
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Tsai YT, Lin CI, Chen HK, Lee KM, Hsu CY, Yang SJ, Yeh NH. Chromatin tethering effects of hNopp140 are involved in the spatial organization of nucleolus and the rRNA gene transcription. J Biomed Sci 2008; 15:471-86. [PMID: 18253863 PMCID: PMC2440943 DOI: 10.1007/s11373-007-9226-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2007] [Accepted: 11/23/2007] [Indexed: 11/29/2022] Open
Abstract
The short arms of five human acrocentric chromosomes contain ribosomal gene (rDNA) clusters where numerous mini-nucleoli arise at the exit of mitosis. These small nucleoli tend to coalesce into one or a few large nucleoli during interphase by unknown mechanisms. Here, we demonstrate that the N- and C-terminal domains of a nucleolar protein, hNopp140, bound respectively to alpha-satellite arrays and rDNA clusters of acrocentric chromosomes for nucleolar formation. The central acidic-and-basic repeated domain of hNopp140, possessing a weak self-self interacting ability, was indispensable for hNopp140 to build up a nucleolar round-shaped structure. The N- or the C-terminally truncated hNopp140 caused nucleolar segregation and was able to alter locations of the rDNA transcription, as mediated by detaching the rDNA repeats from the acrocentric alpha-satellite arrays. Interestingly, an hNopp140 mutant, made by joining the N- and C-terminal domains but excluding the entire central repeated region, induced nucleolar disruption and global chromatin condensation. Furthermore, RNAi knockdown of hNopp140 resulted in dispersion of the rDNA and acrocentric alpha-satellite sequences away from nucleolus that was accompanied by rDNA transcriptional silence. Our findings indicate that hNopp140, a scaffold protein, is involved in the nucleolar assembly, fusion, and maintenance.
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Affiliation(s)
- Yi-Tzang Tsai
- School of Life Science, Institute of Microbiology and Immunology, National Yang-Ming University, 155 Li-Nong Street Sec. 2, Taipei, 112, Taiwan
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Liu X, Liu M, Xue Z, Pan Q, Wu L, Long Z, Xia K, Liang D, Xia J. Non-viral ex vivo transduction of human hepatocyte cells to express factor VIII using a human ribosomal DNA-targeting vector. J Thromb Haemost 2007; 5:347-51. [PMID: 17155951 DOI: 10.1111/j.1538-7836.2007.02355.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND In gene therapy, one of the most important issues is the choice of the vectors. pHrneo is a human-derived vector previously constructed by our group, which can target a foreign gene into a human ribosomal DNA (hrDNA) locus. METHODS AND RESULTS In this study, we inserted an expression cassette of reconstructive hFVIII (hFVIII-BDDAK39) to pHrneo to construct a targeting vector: pHrneo-BDDAK39. Through electroporation of pHrneo-BDDAK39 into HL7702 cells (human hepatocyte), we identified the homologous recombinants using polymerase chain reaction, and tested the expression of hFVIII-BDDAK39 located at the hrDNA locus. The hFVIII-BDDAK39 was successfully targeted into the hrDNA locus of HL7702 by pHrneo-BDDAK39, and the efficiency of site-specific integration was 1.1 x 10(-5). The hFVIII-BDDAK39 at the hrDNA locus of HL7702 was found to be able to express efficiently (4.3 +/- 0.9 ng 10(-6) cells 24 h(-1)). CONCLUSION It has been indicated that the targeting vector pHrneo-BDDAK39 can be used in gene therapy for hemophilia A.
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Affiliation(s)
- X Liu
- National Laboratory of Medical Genetics of China, Xiangya Hospital, Central South University, Changsha, China
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Kobayashi T. Strategies to maintain the stability of the ribosomal RNA gene repeats--collaboration of recombination, cohesion, and condensation. Genes Genet Syst 2007; 81:155-61. [PMID: 16905869 DOI: 10.1266/ggs.81.155] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Ribosomal RNA gene repeats (rDNA) are one of the most characteristic regions in eukaryotic chromosomes. The repeats consist of more than 100 tandem units occupying large part of the chromosome in most of organisms. Cells are known to deal with this "unusual domain" in a unique manner. In this review, I will summarize work on rDNA repeat maintenance, focusing mainly on work done by our group, and show that the maintenance mechanism operates by a collaboration of recombination, sister-chromatid cohesion, and chromatin condensation.
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Affiliation(s)
- Takehiko Kobayashi
- National Institute for Basic Biology and The Graduate University for Advanced Studies SOKENDAI, School of Life Science, Okazaki, Japan.
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Investigation of hrDNA targeting vector-mediated tumor-specific suicide gene therapy for hepatocellular carcinoma. CHINESE SCIENCE BULLETIN-CHINESE 2006. [DOI: 10.1007/s11434-006-2120-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Mais C, Wright JE, Prieto JL, Raggett SL, McStay B. UBF-binding site arrays form pseudo-NORs and sequester the RNA polymerase I transcription machinery. Genes Dev 2005; 19:50-64. [PMID: 15598984 PMCID: PMC540225 DOI: 10.1101/gad.310705] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2004] [Accepted: 10/19/2004] [Indexed: 11/25/2022]
Abstract
Human ribosomal genes (rDNA) are located in nucleolar organizer regions (NORs) on the short arms of acrocentric chromosomes. Metaphase NORs that were transcriptionally active in the previous cell cycle appear as prominent chromosomal features termed secondary constrictions that are achromatic in chromosome banding and positive in silver staining. The architectural RNA polymerase I (pol I) transcription factor UBF binds extensively across rDNA throughout the cell cycle. To determine if UBF binding underpins NOR structure, we integrated large arrays of heterologous UBF-binding sequences at ectopic sites on human chromosomes. These arrays efficiently recruit UBF even to sites outside the nucleolus and, during metaphase, form novel silver stainable secondary constrictions, termed pseudo-NORs, morphologically similar to NORs. We demonstrate for the first time that in addition to UBF the other components of the pol I machinery are found associated with sequences across the entire human rDNA repeat. Remarkably, a significant fraction of these same pol I factors are sequestered by pseudo-NORs independent of both transcription and nucleoli. Because of the heterologous nature of the sequence employed, we infer that sequestration is mediated primarily by protein-protein interactions with UBF. These results suggest that extensive binding of UBF is responsible for formation and maintenance of the secondary constriction at active NORs. Furthermore, we propose that UBF mediates recruitment of the pol I machinery to nucleoli independently of promoter elements.
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Affiliation(s)
- Christine Mais
- Biomedical Research Centre, Ninewells Hospital and Medical School, University of Dundee, Dundee, DD1 9SY Scotland, United Kingdom
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Sullivan GJ, Bridger JM, Cuthbert AP, Newbold RF, Bickmore WA, McStay B. Human acrocentric chromosomes with transcriptionally silent nucleolar organizer regions associate with nucleoli. EMBO J 2001; 20:2867-74. [PMID: 11387219 PMCID: PMC125486 DOI: 10.1093/emboj/20.11.2867] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2000] [Revised: 03/30/2001] [Accepted: 04/03/2001] [Indexed: 11/13/2022] Open
Abstract
Human ribosomal gene repeats are distributed among five nucleolar organizer regions (NORs) on the p arms of acrocentric chromosomes. On exit from mitosis, nucleoli form around individual active NORs. As cells progress through the cycle, these mini-nucleoli fuse to form large nucleoli incorporating multiple NORs. It is generally assumed that nucleolar incorporation of individual NORs is dependent on ribosomal gene transcription. To test this assumption, we determined the nuclear location of individual human acrocentric chromosomes, and their associated NORs, in mouse> human cell hybrids. Human ribosomal genes are transcriptionally silent in this context. Combined immunofluorescence and in situ hybridization (immuno-FISH) on three-dimensional preserved nuclei showed that human acrocentric chromosomes associate with hybrid cell nucleoli. Analysis of purified nucleoli demonstrated that human and mouse NORs are equally likely to be within a hybrid cell nucleolus. This is supported further by the observation that murine upstream binding factor can associate with human NORs. Incorporation of silent NORs into mature nucleoli raises interesting issues concerning the maintenance of the activity status of individual NORs.
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Affiliation(s)
| | - Joanna M. Bridger
- Biomedical Research Centre, University of Dundee, Ninewells Hospital, Dundee DD1 9SY,
Department of Biological Sciences, Brunel University, Uxbridge, Middlesex UB8 3PH and MRC Human Genetics Unit, Crewe Road, Edinburgh EH4 2XU, UK Present address: Division of Medical and Molecular Genetics, Guy’s, King’s and St Thomas’ School of Medicine, London SE1 9RT, UK Corresponding author e-mail:
| | - Andrew P. Cuthbert
- Biomedical Research Centre, University of Dundee, Ninewells Hospital, Dundee DD1 9SY,
Department of Biological Sciences, Brunel University, Uxbridge, Middlesex UB8 3PH and MRC Human Genetics Unit, Crewe Road, Edinburgh EH4 2XU, UK Present address: Division of Medical and Molecular Genetics, Guy’s, King’s and St Thomas’ School of Medicine, London SE1 9RT, UK Corresponding author e-mail:
| | - Robert F. Newbold
- Biomedical Research Centre, University of Dundee, Ninewells Hospital, Dundee DD1 9SY,
Department of Biological Sciences, Brunel University, Uxbridge, Middlesex UB8 3PH and MRC Human Genetics Unit, Crewe Road, Edinburgh EH4 2XU, UK Present address: Division of Medical and Molecular Genetics, Guy’s, King’s and St Thomas’ School of Medicine, London SE1 9RT, UK Corresponding author e-mail:
| | - Wendy A. Bickmore
- Biomedical Research Centre, University of Dundee, Ninewells Hospital, Dundee DD1 9SY,
Department of Biological Sciences, Brunel University, Uxbridge, Middlesex UB8 3PH and MRC Human Genetics Unit, Crewe Road, Edinburgh EH4 2XU, UK Present address: Division of Medical and Molecular Genetics, Guy’s, King’s and St Thomas’ School of Medicine, London SE1 9RT, UK Corresponding author e-mail:
| | - Brian McStay
- Biomedical Research Centre, University of Dundee, Ninewells Hospital, Dundee DD1 9SY,
Department of Biological Sciences, Brunel University, Uxbridge, Middlesex UB8 3PH and MRC Human Genetics Unit, Crewe Road, Edinburgh EH4 2XU, UK Present address: Division of Medical and Molecular Genetics, Guy’s, King’s and St Thomas’ School of Medicine, London SE1 9RT, UK Corresponding author e-mail:
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Csonka E, Cserpán I, Fodor K, Holló G, Katona R, Keresö J, Praznovszky T, Szakál B, Telenius A, deJong G, Udvardy A, Hadlaczky G. Novel generation of human satellite DNA-based artificial chromosomes in mammalian cells. J Cell Sci 2000; 113 ( Pt 18):3207-16. [PMID: 10954419 DOI: 10.1242/jcs.113.18.3207] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
An in vivo approach has been developed for generation of artificial chromosomes, based on the induction of intrinsic, large-scale amplification mechanisms of mammalian cells. Here, we describe the successful generation of prototype human satellite DNA-based artificial chromosomes via amplification-dependent de novo chromosome formations induced by integration of exogenous DNA sequences into the centromeric/rDNA regions of human acrocentric chromosomes. Subclones with mitotically stable de novo chromosomes were established, which allowed the initial characterization and purification of these artificial chromosomes. Because of the low complexity of their DNA content, they may serve as a useful tool to study the structure and function of higher eukaryotic chromosomes. Human satellite DNA-based artificial chromosomes containing amplified satellite DNA, rDNA, and exogenous DNA sequences were heterochromatic, however, they provided a suitable chromosomal environment for the expression of the integrated exogenous genetic material. We demonstrate that induced de novo chromosome formation is a reproducible and effective methodology in generating artificial chromosomes from predictable sequences of different mammalian species. Satellite DNA-based artificial chromosomes formed by induced large-scale amplifications on the short arm of human acrocentric chromosomes may become safe or low risk vectors in gene therapy.
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Affiliation(s)
- E Csonka
- Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, H-6701 Szeged, PO Box 521, Hungary
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Yan PS, Rodriguez FJ, Laux DE, Perry MR, Standiford SB, Huang TH. Hypermethylation of ribosomal DNA in human breast carcinoma. Br J Cancer 2000; 82:514-7. [PMID: 10682657 PMCID: PMC2363317 DOI: 10.1054/bjoc.1999.0955] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We examined the methylation status of the transcribed domain of ribosomal DNA (rDNA) in 58 patients with breast cancer. The mean percent of methylation was significantly higher in breast tumours than that of normal control samples (P < 0.0001). This increased rDNA methylation was associated with oestrogen receptor non-expression (P < 0.0273) and with moderately or poorly differentiated tumours as compared to well differentiated tumours (P < 0.0475). Our results suggest that rDNA can be a useful marker for monitoring aberrant methylation during breast tumour progression.
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Affiliation(s)
- P S Yan
- Department of Pathology and Anatomical Sciences, Ellis Fischel Cancer Center, University of Missouri, Columbia 65203, USA
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