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Frey T, Murakami T, Maki K, Kawaue T, Tani N, Sugai A, Nakazawa N, Ishiguro K, Adachi T, Kengaku M, Ohki K, Gotoh Y, Kishi Y. Age-associated reduction of nuclear shape dynamics in excitatory neurons of the visual cortex. Aging Cell 2023; 22:e13925. [PMID: 37476844 PMCID: PMC10497821 DOI: 10.1111/acel.13925] [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: 01/10/2023] [Revised: 06/19/2023] [Accepted: 06/21/2023] [Indexed: 07/22/2023] Open
Abstract
Neurons decline in their functionality over time, and age-related neuronal alterations are associated with phenotypes of neurodegenerative diseases. In nonneural tissues, an infolded nuclear shape has been proposed as a hallmark of aged cells and neurons with infolded nuclei have also been reported to be associated with neuronal activity. Here, we performed time-lapse imaging in the visual cortex of Nex-Cre;SUN1-GFP mice. Nuclear infolding was observed within 10 min of stimulation in young nuclei, while the aged nuclei were already infolded pre-stimulation and showed reduced dynamics of the morphology. In young nuclei, the depletion of the stimuli restored the nucleus to a spherical shape and reduced the dynamic behavior, suggesting that nuclear infolding is a reversible process. We also found the aged nucleus to be stiffer than the young one, further relating to the age-associated loss of nuclear shape dynamics. We reveal temporal changes in the nuclear shape upon external stimulation and observe that these morphological dynamics decrease with age.
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Affiliation(s)
- Tanita Frey
- Graduate School of Pharmaceutical SciencesThe University of TokyoTokyoJapan
- New York University Grossman School of MedicineNew YorkNew YorkUSA
| | - Tomonari Murakami
- Graduate School of MedicineThe University of TokyoTokyoJapan
- Institute for AI and Beyond, The University of TokyoTokyoJapan
| | - Koichiro Maki
- Institute for Life and Medical Sciences, Kyoto UniversityKyotoJapan
| | - Takumi Kawaue
- Institute for Integrated Cell‐Material Sciences, Institute for Advanced Study, Kyoto UniversityKyotoJapan
| | - Naoki Tani
- Liaison Laboratory Research Promotion CenterIMEG, Kumamoto UniversityKumamotoJapan
| | - Ayaka Sugai
- Graduate School of Pharmaceutical SciencesThe University of TokyoTokyoJapan
- Institute for Quantitative Biosciences, The University of TokyoTokyoJapan
| | - Naotaka Nakazawa
- Institute for Integrated Cell‐Material Sciences, Institute for Advanced Study, Kyoto UniversityKyotoJapan
- Department of Energy and Materials, Faculty of Science and EngineeringKindai UniversityOsakaJapan
| | - Kei‐ichiro Ishiguro
- Department of Chromosome BiologyInstitute of Molecular Embryology and Genetics (IMEG), Kumamoto UniversityKumamotoJapan
| | - Taiji Adachi
- Institute for Life and Medical Sciences, Kyoto UniversityKyotoJapan
| | - Mineko Kengaku
- Institute for Integrated Cell‐Material Sciences, Institute for Advanced Study, Kyoto UniversityKyotoJapan
| | - Kenichi Ohki
- Graduate School of MedicineThe University of TokyoTokyoJapan
- Institute for AI and Beyond, The University of TokyoTokyoJapan
- International Research Center for Neurointelligence (WPI‐IRCN), The University of TokyoTokyoJapan
| | - Yukiko Gotoh
- Graduate School of Pharmaceutical SciencesThe University of TokyoTokyoJapan
- International Research Center for Neurointelligence (WPI‐IRCN), The University of TokyoTokyoJapan
| | - Yusuke Kishi
- Graduate School of Pharmaceutical SciencesThe University of TokyoTokyoJapan
- Institute for Quantitative Biosciences, The University of TokyoTokyoJapan
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Satomi E, Ueda M, Katahira J, Hieda M. The SUN1 splicing variants SUN1_888 and SUN1_916 differentially regulate nucleolar structure. Genes Cells 2020; 25:730-740. [PMID: 32931086 DOI: 10.1111/gtc.12807] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 08/27/2020] [Accepted: 09/07/2020] [Indexed: 12/22/2022]
Abstract
The nucleolar structure is highly dynamic and strictly regulated in response to internal cues, such as metabolic rates, and to external cues, such as mechanical forces applied to cells. Although the multilayered nucleolar structure is largely determined by the liquid-like properties of RNA and proteins, the mechanisms regulating the morphology and number of nucleoli remain elusive. The linker of the nucleoskeleton and cytoskeleton (LINC) complex comprises inner nuclear membrane Sad1/UNC-84 (SUN) proteins and outer nuclear membrane-localized nesprins. We previously showed that the depletion of SUN1 proteins affects nucleolar morphologies. This study focuses on the function of SUN1 splicing variants in determining nucleolar morphology. An RNA interference strategy showed that the predominantly expressed variants, SUN1_888 and SUN1_916, were crucial for nucleolar morphology but functionally distinct. In addition, the depletion of either SUN1_888 or SUN1_916 altered the chromatin structure and affected the distribution of histone modifications. Based on these results, we propose a model in which the LINC complex plays a role in modulating nucleolar morphology and numbers via chromatin.
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Affiliation(s)
- Erina Satomi
- Graduate School of Health Sciences, Ehime Prefectural University of Health Sciences, Ehime, Japan
| | - Masako Ueda
- Graduate School of Health Sciences, Ehime Prefectural University of Health Sciences, Ehime, Japan
| | - Jun Katahira
- Department of Veterinary Sciences, Osaka Prefecture University, Osaka, Japan
| | - Miki Hieda
- Graduate School of Health Sciences, Ehime Prefectural University of Health Sciences, Ehime, Japan
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Nucleolar Organization and Functions in Health and Disease. Cells 2020; 9:cells9030526. [PMID: 32106410 PMCID: PMC7140423 DOI: 10.3390/cells9030526] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 02/21/2020] [Indexed: 12/18/2022] Open
Abstract
The nucleolus is a prominent, membraneless compartment found within the nucleus of eukaryotic cells. It forms around ribosomal RNA (rRNA) genes, where it coordinates the transcription, processing, and packaging of rRNA to produce ribosomal subunits. Recent efforts to characterize the biophysical properties of the nucleolus have transformed our understanding of the assembly and organization of this dynamic compartment. Indeed, soluble macromolecules condense from the nucleoplasm to form nucleoli through a process called liquid–liquid phase separation. Individual nucleolar components rapidly exchange with the nucleoplasm and separate within the nucleolus itself to form distinct subcompartments. In addition to its essential role in ribosome biogenesis, the nucleolus regulates many aspects of cell physiology, including genome organization, stress responses, senescence and lifespan. Consequently, the nucleolus is implicated in several human diseases, such as Hutchinson–Gilford progeria syndrome, Diamond–Blackfan anemia, and various forms of cancer. This Special Issue highlights new insights into the physical and molecular mechanisms that control the architecture and diverse functions of the nucleolus, and how they break down in disease.
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Marnef A, Finoux AL, Arnould C, Guillou E, Daburon V, Rocher V, Mangeat T, Mangeot PE, Ricci EP, Legube G. A cohesin/HUSH- and LINC-dependent pathway controls ribosomal DNA double-strand break repair. Genes Dev 2019; 33:1175-1190. [PMID: 31395742 PMCID: PMC6719620 DOI: 10.1101/gad.324012.119] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 06/26/2019] [Indexed: 02/01/2023]
Abstract
The ribosomal DNA (rDNA) represents a particularly unstable locus undergoing frequent breakage. DNA double-strand breaks (DSBs) within rDNA induce both rDNA transcriptional repression and nucleolar segregation, but the link between the two events remains unclear. Here we found that DSBs induced on rDNA trigger transcriptional repression in a cohesin- and HUSH (human silencing hub) complex-dependent manner throughout the cell cycle. In S/G2 cells, transcriptional repression is further followed by extended resection within the interior of the nucleolus, DSB mobilization at the nucleolar periphery within nucleolar caps, and repair by homologous recombination. We showed that nuclear envelope invaginations frequently connect the nucleolus and that rDNA DSB mobilization, but not transcriptional repression, involves the nuclear envelope-associated LINC complex and the actin pathway. Altogether, our data indicate that rDNA break localization at the nucleolar periphery is not a direct consequence of transcriptional repression but rather is an active process that shares features with the mobilization of persistent DSB in active genes and heterochromatin.
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Affiliation(s)
- Aline Marnef
- Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération (LBCMCP), Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, Toulouse 31062, France
| | - Anne-Laure Finoux
- Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération (LBCMCP), Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, Toulouse 31062, France
| | - Coline Arnould
- Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération (LBCMCP), Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, Toulouse 31062, France
| | - Emmanuelle Guillou
- Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération (LBCMCP), Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, Toulouse 31062, France
| | - Virginie Daburon
- Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération (LBCMCP), Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, Toulouse 31062, France
| | - Vincent Rocher
- Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération (LBCMCP), Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, Toulouse 31062, France
| | - Thomas Mangeat
- Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération (LBCMCP), Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, Toulouse 31062, France
| | - Philippe E Mangeot
- International Center for Infectiology Research (CIRI), Ecole Normale Supérieure de Lyon (ENS), U1111, Institut National de la Santé et de la Recherche Médicale (INSERM), UMR5308, Centre National de la Recherche Scientifique (CNRS), Université Claude Bernard Lyon 1, Université Lyon, Lyon F-6900, France
| | - Emiliano P Ricci
- Laboratoire de Biologie et Modélisation de la Cellule (LBMC), Ecole Normale Supérieure de Lyon (ENS), U1210, Institut National de la Santé et de la Recherche Médicale (INSERM), UMR5239, Centre National de la Recherche Scientifique (CNRS), Université Claude Bernard Lyon 1, Université de Lyon, Lyon F-69007, France
| | - Gaëlle Legube
- Laboratoire de Biologie Cellulaire et Moléculaire du Contrôle de la Prolifération (LBCMCP), Centre de Biologie Intégrative (CBI), Centre National de la Recherche Scientifique (CNRS), Université de Toulouse, Toulouse 31062, France
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