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D'Alfonso A, Micheli G, Camilloni G. rDNA transcription, replication and stability in Saccharomyces cerevisiae. Semin Cell Dev Biol 2024; 159-160:1-9. [PMID: 38244478 DOI: 10.1016/j.semcdb.2024.01.004] [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: 05/01/2023] [Revised: 12/20/2023] [Accepted: 01/10/2024] [Indexed: 01/22/2024]
Abstract
The ribosomal DNA locus (rDNA) is central for the functioning of cells because it encodes ribosomal RNAs, key components of ribosomes, and also because of its links to fundamental metabolic processes, with significant impact on genome integrity and aging. The repetitive nature of the rDNA gene units forces the locus to maintain sequence homogeneity through recombination processes that are closely related to genomic stability. The co-presence of basic DNA transactions, such as replication, transcription by major RNA polymerases, and recombination, in a defined and restricted area of the genome is of particular relevance as it affects the stability of the rDNA locus by both direct and indirect mechanisms. This condition is well exemplified by the rDNA of Saccharomyces cerevisiae. In this review we summarize essential knowledge on how the complexity and overlap of different processes contribute to the control of rDNA and genomic stability in this model organism.
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Affiliation(s)
- Anna D'Alfonso
- Dipartimento di Biologia e Biotecnologie C. Darwin, Università degli studi di Roma, Sapienza, Rome, Italy
| | - Gioacchino Micheli
- Istituto di Biologia e Patologia Molecolari, Consiglio Nazionale delle Ricerche, Rome, Italy
| | - Giorgio Camilloni
- Dipartimento di Biologia e Biotecnologie C. Darwin, Università degli studi di Roma, Sapienza, Rome, Italy.
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Murai T, Yanagi S, Hori Y, Kobayashi T. Replication fork blocking deficiency leads to a reduction of rDNA copy number in budding yeast. iScience 2024; 27:109120. [PMID: 38384843 PMCID: PMC10879690 DOI: 10.1016/j.isci.2024.109120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 11/27/2023] [Accepted: 01/31/2024] [Indexed: 02/23/2024] Open
Abstract
The ribosomal RNA genes are encoded as hundreds of tandem repeats, known as the rDNA, in eukaryotes. Maintaining these copies seems to be necessary, but copy number changes in an active manner have been reported in only frogs, flies, Neurospora, and yeast. In the best-studied system, yeast, a protein (Fob1) binds to the rDNA and unidirectionally blocks the replication fork. This block stimulates rDNA double-strand breaks (DSBs) leading to recombination and copy number change. To date, copy number maintenance and concerted evolution mediated by rDNA repeat turnover were the proposed benefits of Fob1-dependent replication fork arrest. In this study, we tested whether Fob1 provides these benefits and found that rDNA copy number decreases when FOB1 is deleted, suggesting that Fob1 is important for recovery from low copy number. We suppose that replication fork stalling at rDNA is necessary for recovering from rDNA copy number loss in other species as well.
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Affiliation(s)
- Taichi Murai
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Shuichi Yanagi
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Yutaro Hori
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
| | - Takehiko Kobayashi
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
- Department of Biological Sciences, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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Hasegawa Y, Ooka H, Wakatsuki T, Sasaki M, Yamamoto A, Kobayashi T. Acidic growth conditions stabilize the ribosomal RNA gene cluster and extend lifespan through noncoding transcription repression. Genes Cells 2024; 29:111-130. [PMID: 38069450 DOI: 10.1111/gtc.13089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 11/07/2023] [Accepted: 11/19/2023] [Indexed: 02/06/2024]
Abstract
Blackcurrant (Ribes nigrum L.) is a classical fruit that has long been used to make juice, jam, and liqueur. Blackcurrant extract is known to relieve cells from DNA damage caused by hydrogen peroxide (H2 O2 ), methyl methane sulfonate (MMS), and ultraviolet (UV) radiation. We found that blackcurrant extract (BCE) stabilizes the ribosomal RNA gene cluster (rDNA), one of the most unstable regions in the genome, through repression of noncoding transcription in the intergenic spacer (IGS) which extended the lifespan in budding yeast. Reduced formation of extrachromosomal circles (ERCs) after exposure to fractionated BCE suggested that acidity of the growth medium impacted rDNA stability. Indeed, alteration of the acidity of the growth medium to pH ~4.5 by adding HCl increased rDNA stability and extended the lifespan. We identified RPD3 as the gene responsible for this change, which was mediated by the RPD3L histone deacetylase complex. In mammals, as inflammation sites in a tissue are acidic, DNA maintenance may be similarly regulated to prevent genome instability from causing cancer.
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Affiliation(s)
- Yo Hasegawa
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, Bunkyo-ku, Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Japan
| | - Hiroyuki Ooka
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, Bunkyo-ku, Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Japan
| | - Tsuyoshi Wakatsuki
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, Bunkyo-ku, Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Japan
- Department of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Japan
| | - Mariko Sasaki
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, Bunkyo-ku, Japan
| | - Ayumi Yamamoto
- Department of Industrial System Engineering, Hachinohe College, Hachinohe, Japan
| | - Takehiko Kobayashi
- Laboratory of Genome Regeneration, Institute for Quantitative Biosciences (IQB), The University of Tokyo, Bunkyo-ku, Japan
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Japan
- Department of Life Science and Technology, Tokyo Institute of Technology, Midori-ku, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Japan
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