1
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Sibai DS, Tremblay MG, Lessard F, Tav C, Sabourin-Félix M, Robinson M, Moss T. TTF1 control of LncRNA synthesis delineates a tumor suppressor pathway directly regulating the ribosomal RNA genes. J Cell Physiol 2024. [PMID: 38764354 DOI: 10.1002/jcp.31303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 04/29/2024] [Accepted: 05/02/2024] [Indexed: 05/21/2024]
Abstract
The tumor suppressor p14/19ARF regulates ribosomal RNA (rRNA) synthesis by controlling the nucleolar localization of Transcription Termination Factor 1 (TTF1). However, the role played by TTF1 in regulating the rRNA genes and in potentially controlling growth has remained unclear. We now show that TTF1 expression regulates cell growth by determining the cellular complement of ribosomes. Unexpectedly, it achieves this by acting as a "roadblock" to synthesis of the noncoding LncRNA and pRNA that we show are generated from the "Spacer Promoter" duplications present upstream of the 47S pre-rRNA promoter on the mouse and human ribosomal RNA genes. Unexpectedly, the endogenous generation of these noncoding RNAs does not induce CpG methylation or gene silencing. Rather, it acts in cis to suppress 47S preinitiation complex formation and hence de novo pre-rRNA synthesis by a mechanism reminiscent of promoter interference or occlusion. Taken together, our data delineate a pathway from p19ARF to cell growth suppression via the regulation of ribosome biogenesis by noncoding RNAs and validate a key cellular growth law in mammalian cells.
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Affiliation(s)
- Dany S Sibai
- St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre, Laval University, Quebec City, Quebec, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Quebec City, Quebec, Canada
- Cancer Research Centre, Laval University, Quebec City, Quebec, Canada
| | - Michel G Tremblay
- St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre, Laval University, Quebec City, Quebec, Canada
| | - Frédéric Lessard
- St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre, Laval University, Quebec City, Quebec, Canada
| | - Christophe Tav
- St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre, Laval University, Quebec City, Quebec, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Quebec City, Quebec, Canada
- Cancer Research Centre, Laval University, Quebec City, Quebec, Canada
| | - Marianne Sabourin-Félix
- St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre, Laval University, Quebec City, Quebec, Canada
| | - Mark Robinson
- Department of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | - Tom Moss
- St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre, Laval University, Quebec City, Quebec, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Quebec City, Quebec, Canada
- Cancer Research Centre, Laval University, Quebec City, Quebec, Canada
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2
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LeDoux MS. Polymerase I as a Target for Treating Neurodegenerative Disorders. Biomedicines 2024; 12:1092. [PMID: 38791054 PMCID: PMC11118182 DOI: 10.3390/biomedicines12051092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 05/06/2024] [Accepted: 05/11/2024] [Indexed: 05/26/2024] Open
Abstract
Polymerase I (Pol I) is at the epicenter of ribosomal RNA (rRNA) synthesis. Pol I is a target for the treatment of cancer. Given the many cellular commonalities between cancer and neurodegeneration (i.e., different faces of the same coin), it seems rational to consider targeting Pol I or, more generally, rRNA synthesis for the treatment of disorders associated with the death of terminally differentiated neurons. Principally, ribosomes synthesize proteins, and, accordingly, Pol I can be considered the starting point for protein synthesis. Given that cellular accumulation of abnormal proteins such as α-synuclein and tau is an essential feature of neurodegenerative disorders such as Parkinson disease and fronto-temporal dementia, reduction of protein production is now considered a viable target for treatment of these and closely related neurodegenerative disorders. Abnormalities in polymerase I activity and rRNA production may also be associated with nuclear and nucleolar stress, DNA damage, and childhood-onset neuronal death, as is the case for the UBTF E210K neuroregression syndrome. Moreover, restraining the activity of Pol I may be a viable strategy to slow aging. Before starting down the road of Pol I inhibition for treating non-cancerous disorders of the nervous system, many questions must be answered. First, how much Pol I inhibition can neurons tolerate, and for how long? Should inhibition of Pol I be continuous or pulsed? Will cells compensate for Pol I inhibition by upregulating the number of active rDNAs? At present, we have no effective and safe disease modulatory treatments for Alzheimer disease, α-synucleinopathies, or tauopathies, and novel therapeutic targets and approaches must be explored.
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Affiliation(s)
- Mark S. LeDoux
- Department of Psychology and College of Health Sciences, University of Memphis, Memphis, TN 38152, USA; or
- Veracity Neuroscience LLC, Memphis, TN 38157, USA
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3
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Paralkar VR. Transcription factor regulation of ribosomal RNA in hematopoiesis. Curr Opin Hematol 2024:00062752-990000000-00069. [PMID: 38568093 DOI: 10.1097/moh.0000000000000816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
PURPOSE OF REVIEW Ribosomal RNAs (rRNAs) are transcribed within nucleoli from rDNA repeats by RNA Polymerase I (Pol I). There is variation in rRNA transcription rates across the hematopoietic tree, and leukemic blast cells have prominent nucleoli, indicating abundant ribosome biogenesis. The mechanisms underlying these variations are poorly understood. The purpose of this review is to summarize findings of rDNA binding and Pol I regulation by hematopoietic transcription factors. RECENT FINDINGS Our group recently used custom genome assemblies optimized for human and mouse rDNA mapping to map nearly 2200 ChIP-Seq datasets for nearly 250 factors to rDNA, allowing us to identify conserved occupancy patterns for multiple transcription factors. We confirmed known rDNA occupancy of MYC and RUNX factors, and identified new binding sites for CEBP factors, IRF factors, and SPI1 at canonical motif sequences. We also showed that CEBPA degradation rapidly leads to reduced Pol I occupancy and nascent rRNA in mouse myeloid cells. SUMMARY We propose that a number of hematopoietic transcription factors bind rDNA and potentially regulate rRNA transcription. Our model has implications for normal and malignant hematopoiesis. This review summarizes the literature, and outlines experimental considerations to bear in mind while dissecting transcription factor roles on rDNA.
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Affiliation(s)
- Vikram R Paralkar
- Division of Hematology and Oncology, Department of Medicine
- Department of Cell and Developmental Biology
- Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
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4
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Bryant CJ, McCool MA, Rosado González G, Abriola L, Surovtseva Y, Baserga S. Discovery of novel microRNA mimic repressors of ribosome biogenesis. Nucleic Acids Res 2024; 52:1988-2011. [PMID: 38197221 PMCID: PMC10899765 DOI: 10.1093/nar/gkad1235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Revised: 12/03/2023] [Accepted: 12/16/2023] [Indexed: 01/11/2024] Open
Abstract
While microRNAs and other non-coding RNAs are the next frontier of novel regulators of mammalian ribosome biogenesis (RB), a systematic exploration of microRNA-mediated RB regulation has not yet been undertaken. We carried out a high-content screen in MCF10A cells for changes in nucleolar number using a library of 2603 mature human microRNA mimics. Following a secondary screen for nucleolar rRNA biogenesis inhibition, we identified 72 novel microRNA negative regulators of RB after stringent hit calling. Hits included 27 well-conserved microRNAs present in MirGeneDB, and were enriched for mRNA targets encoding proteins with nucleolar localization or functions in cell cycle regulation. Rigorous selection and validation of a subset of 15 microRNA hits unexpectedly revealed that most of them caused dysregulated pre-rRNA processing, elucidating a novel role for microRNAs in RB regulation. Almost all hits impaired global protein synthesis and upregulated CDKN1A (p21) levels, while causing diverse effects on RNA Polymerase 1 (RNAP1) transcription and TP53 protein levels. We provide evidence that the MIR-28 siblings, hsa-miR-28-5p and hsa-miR-708-5p, potently target the ribosomal protein mRNA RPS28 via tandem primate-specific 3' UTR binding sites, causing a severe pre-18S pre-rRNA processing defect. Our work illuminates novel microRNA attenuators of RB, forging a promising new path for microRNA mimic chemotherapeutics.
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Affiliation(s)
- Carson J Bryant
- Department of Molecular Biophysics and Biochemistry, Yale School of Medicine, New Haven, CT, 06520, USA
| | - Mason A McCool
- Department of Molecular Biophysics and Biochemistry, Yale School of Medicine, New Haven, CT, 06520, USA
| | | | - Laura Abriola
- Yale Center for Molecular Discovery, Yale University, West Haven, CT, 06516, USA
| | - Yulia V Surovtseva
- Yale Center for Molecular Discovery, Yale University, West Haven, CT, 06516, USA
| | - Susan J Baserga
- Department of Molecular Biophysics and Biochemistry, Yale School of Medicine, New Haven, CT, 06520, USA
- Department of Genetics, Yale School of Medicine, New Haven, CT, 06520, USA
- Department of Therapeutic Radiology, Yale School of Medicine, New Haven, CT, 06520, USA
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5
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Barajas JM, Rasouli M, Umeda M, Hiltenbrand R, Abdelhamed S, Mohnani R, Arthur B, Westover T, Thomas ME, Ashtiani M, Janke LJ, Xu B, Chang TC, Rosikiewicz W, Xiong E, Rolle C, Low J, Krishan R, Song G, Walsh MP, Ma J, Rubnitz JE, Iacobucci I, Chen T, Krippner-Heidenreich A, Zwaan CM, Heidenreich O, Klco JM. Acute myeloid leukemias with UBTF tandem duplications are sensitive to menin inhibitors. Blood 2024; 143:619-630. [PMID: 37890156 PMCID: PMC10873536 DOI: 10.1182/blood.2023021359] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 09/29/2023] [Accepted: 10/20/2023] [Indexed: 10/29/2023] Open
Abstract
ABSTRACT UBTF tandem duplications (UBTF-TDs) have recently emerged as a recurrent alteration in pediatric and adult acute myeloid leukemia (AML). UBTF-TD leukemias are characterized by a poor response to conventional chemotherapy and a transcriptional signature that mirrors NUP98-rearranged and NPM1-mutant AMLs, including HOX-gene dysregulation. However, the mechanism by which UBTF-TD drives leukemogenesis remains unknown. In this study, we investigated the genomic occupancy of UBTF-TD in transformed cord blood CD34+ cells and patient-derived xenograft models. We found that UBTF-TD protein maintained genomic occupancy at ribosomal DNA loci while also occupying genomic targets commonly dysregulated in UBTF-TD myeloid malignancies, such as the HOXA/HOXB gene clusters and MEIS1. These data suggest that UBTF-TD is a gain-of-function alteration that results in mislocalization to genomic loci dysregulated in UBTF-TD leukemias. UBTF-TD also co-occupies key genomic loci with KMT2A and menin, which are known to be key partners involved in HOX-dysregulated leukemias. Using a protein degradation system, we showed that stemness, proliferation, and transcriptional signatures are dependent on sustained UBTF-TD localization to chromatin. Finally, we demonstrate that primary cells from UBTF-TD leukemias are sensitive to the menin inhibitor SNDX-5613, resulting in markedly reduced in vitro and in vivo tumor growth, myeloid differentiation, and abrogation of the UBTF-TD leukemic expression signature. These findings provide a viable therapeutic strategy for patients with this high-risk AML subtype.
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Affiliation(s)
- Juan M. Barajas
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Milad Rasouli
- Princess Maxima Center for Pediatric Oncology, Utrecht, The Netherlands
- Department of Pediatric Hematology/Oncology, Erasmus MC-Sophia Children’s Hospital, Rotterdam, The Netherlands
| | - Masayuki Umeda
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Ryan Hiltenbrand
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Sherif Abdelhamed
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Rebecca Mohnani
- Princess Maxima Center for Pediatric Oncology, Utrecht, The Netherlands
| | - Bright Arthur
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Tamara Westover
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Melvin E. Thomas
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Minoo Ashtiani
- Princess Maxima Center for Pediatric Oncology, Utrecht, The Netherlands
| | - Laura J. Janke
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Beisi Xu
- Center for Applied Bioinformatics, St. Jude Children’s Research Hospital, Memphis, TN
| | - Ti-Cheng Chang
- Center for Applied Bioinformatics, St. Jude Children’s Research Hospital, Memphis, TN
| | - Wojciech Rosikiewicz
- Center for Applied Bioinformatics, St. Jude Children’s Research Hospital, Memphis, TN
| | - Emily Xiong
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Chandra Rolle
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Jonathan Low
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN
| | - Reethu Krishan
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Guangchun Song
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Michael P. Walsh
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Jing Ma
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Jeffrey E. Rubnitz
- Department of Oncology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Ilaria Iacobucci
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
| | - Taosheng Chen
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, TN
| | | | - Christian M. Zwaan
- Princess Maxima Center for Pediatric Oncology, Utrecht, The Netherlands
- Department of Pediatric Hematology/Oncology, Erasmus MC-Sophia Children’s Hospital, Rotterdam, The Netherlands
| | - Olaf Heidenreich
- Princess Maxima Center for Pediatric Oncology, Utrecht, The Netherlands
- Wolfson Childhood Cancer Research Centre, Translational and Clinical Research Institute, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Jeffery M. Klco
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN
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6
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de Luna Vitorino FN, Levy MJ, Mansano Wailemann RA, Lopes M, Silva ML, Sardiu ME, Garcia BA, Machado Motta MC, Oliveira CC, Armelin HA, Florens LA, Washburn MP, Pinheiro Chagas da Cunha J. The antiproliferative effect of FGF2 in K-Ras-driven tumor cells involves modulation of rRNA and the nucleolus. J Cell Sci 2023; 136:jcs260989. [PMID: 37921359 DOI: 10.1242/jcs.260989] [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: 01/18/2023] [Accepted: 10/24/2023] [Indexed: 11/04/2023] Open
Abstract
The nucleolus is sensitive to stress and can orchestrate a chain of cellular events in response to stress signals. Despite being a growth factor, FGF2 has antiproliferative and tumor-suppressive functions in some cellular contexts. In this work, we investigated how the antiproliferative effect of FGF2 modulates chromatin-, nucleolus- and rDNA-associated proteins. The chromatin and nucleolar proteome indicated that FGF2 stimulation modulates proteins related to transcription, rRNA expression and chromatin-remodeling proteins. The global transcriptional rate and nucleolus area increased along with nucleolar disorganization upon 24 h of FGF2 stimulation. FGF2 stimulation induced immature rRNA accumulation by increasing rRNA transcription. The rDNA-associated protein analysis reinforced that FGF2 stimulus interferes with transcription and rRNA processing. RNA Pol I inhibition partially reversed the growth arrest induced by FGF2, indicating that changes in rRNA expression might be crucial for triggering the antiproliferative effect. Taken together, we demonstrate that the antiproliferative FGF2 stimulus triggers significant transcriptional changes and modulates the main cell transcription site, the nucleolus.
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Affiliation(s)
- Francisca N de Luna Vitorino
- Laboratório de Ciclo Celular - Center of Toxins, Immune-Response and Cell Signalling - CeTICS, Instituto Butantan, São Paulo, SP 055503-900, Brazil
- Programa de Pós-Graduação Interunidades em Biotecnologia, Universidade de São Paulo, São Paulo, SP 05508-000, Brazil
| | - Michaella J Levy
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Rosangela A Mansano Wailemann
- Laboratório de Ciclo Celular - Center of Toxins, Immune-Response and Cell Signalling - CeTICS, Instituto Butantan, São Paulo, SP 055503-900, Brazil
| | - Mariana Lopes
- Laboratório de Ciclo Celular - Center of Toxins, Immune-Response and Cell Signalling - CeTICS, Instituto Butantan, São Paulo, SP 055503-900, Brazil
| | - Mariana Loterio Silva
- Laboratório de Ciclo Celular - Center of Toxins, Immune-Response and Cell Signalling - CeTICS, Instituto Butantan, São Paulo, SP 055503-900, Brazil
| | - Mihaela E Sardiu
- Stowers Institute for Medical Research, Kansas City, MO 64110, USA
| | - Benjamin A Garcia
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO, USA
| | - Maria Cristina Machado Motta
- Laboratório de Ultraestrutura Celular Hertha Meyer, Centro de Pesquisa em Medicina de Precisão, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro-UFRJ, Rio de Janeiro, RJ 21491-590, Brazil
- Centro Nacional de Biologia Estrutural e Bioimagem, Rio de Janeiro, RJ 21941-902, Brazil
| | - Carla Columbano Oliveira
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, SP 05508-000, Brazil
| | - Hugo Aguirre Armelin
- Laboratório de Ciclo Celular - Center of Toxins, Immune-Response and Cell Signalling - CeTICS, Instituto Butantan, São Paulo, SP 055503-900, Brazil
| | | | | | - Julia Pinheiro Chagas da Cunha
- Laboratório de Ciclo Celular - Center of Toxins, Immune-Response and Cell Signalling - CeTICS, Instituto Butantan, São Paulo, SP 055503-900, Brazil
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7
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Barajas JM, Umeda M, Contreras L, Khanlari M, Westover T, Walsh MP, Xiong E, Yang C, Otero B, Arribas-Layton M, Abdelhamed S, Song G, Ma X, Thomas ME, Ma J, Klco JM. UBTF Tandem Duplications in Pediatric MDS and AML: Implications for Clinical Screening and Diagnosis. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2023:2023.11.13.23298320. [PMID: 38014207 PMCID: PMC10680889 DOI: 10.1101/2023.11.13.23298320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Recent genomic studies in adult and pediatric acute myeloid leukemia (AML) demonstrated recurrent in-frame tandem duplications (TD) in exon 13 of upstream binding transcription factor (UBTF). These alterations, which account for ~4.3% of AMLs in childhood and up to 3% in adult AMLs under 60, are subtype-defining and associated with poor outcomes. Here, we provide a comprehensive investigation into the clinicopathological features of UBTF-TD myeloid neoplasms in childhood, including 89 unique pediatric AML and 6 myelodysplastic syndrome (MDS) cases harboring a tandem duplication in exon 13 of UBTF. We demonstrate that UBTF-TD myeloid tumors are associated with dysplastic features, low bone marrow blast infiltration, and low white blood cell count. Furthermore, using bulk and single-cell analyses, we confirm that UBTF-TD is an early and clonal event associated with a distinct transcriptional profile, whereas the acquisition of FLT3 or WT1 mutations is associated with more stem cell-like programs. Lastly, we report rare duplications within exon 9 of UBTF that phenocopy exon 13 duplications, expanding the spectrum of UBTF alterations in pediatric myeloid tumors. Collectively, we comprehensively characterize pediatric AML and MDS with UBTF-TD and highlight key clinical and pathologic features that distinguish this new entity from other molecular subtypes of AML.
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Affiliation(s)
- Juan M. Barajas
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Masayuki Umeda
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Lisett Contreras
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Mahsa Khanlari
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Tamara Westover
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Michael P. Walsh
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Emily Xiong
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | | | | | | | - Sherif Abdelhamed
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Guangchun Song
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Xiaotu Ma
- Department of Computational Biology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Melvin E. Thomas
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Jing Ma
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Jeffery M. Klco
- Department of Pathology, St. Jude Children’s Research Hospital, Memphis, TN, USA
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8
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Yang ZY, Yan XC, Zhang JYL, Liang L, Gao CC, Zhang PR, Liu Y, Sun JX, Ruan B, Duan JL, Wang RN, Feng XX, Che B, Xiao T, Han H. Repression of rRNA gene transcription by endothelial SPEN deficiency normalizes tumor vasculature via nucleolar stress. J Clin Invest 2023; 133:e159860. [PMID: 37607001 PMCID: PMC10575731 DOI: 10.1172/jci159860] [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: 03/03/2022] [Accepted: 08/17/2023] [Indexed: 08/23/2023] Open
Abstract
Human cancers induce a chaotic, dysfunctional vasculature that promotes tumor growth and blunts most current therapies; however, the mechanisms underlying the induction of a dysfunctional vasculature have been unclear. Here, we show that split end (SPEN), a transcription repressor, coordinates rRNA synthesis in endothelial cells (ECs) and is required for physiological and tumor angiogenesis. SPEN deficiency attenuated EC proliferation and blunted retinal angiogenesis, which was attributed to p53 activation. Furthermore, SPEN knockdown activated p53 by upregulating noncoding promoter RNA (pRNA), which represses rRNA transcription and triggers p53-mediated nucleolar stress. In human cancer biopsies, a low endothelial SPEN level correlated with extended overall survival. In mice, endothelial SPEN deficiency compromised rRNA expression and repressed tumor growth and metastasis by normalizing tumor vessels, and this was abrogated by p53 haploinsufficiency. rRNA gene transcription is driven by RNA polymerase I (RNPI). We found that CX-5461, an RNPI inhibitor, recapitulated the effect of Spen ablation on tumor vessel normalization and combining CX-5461 with cisplatin substantially improved the efficacy of treating tumors in mice. Together, these results demonstrate that SPEN is required for angiogenesis by repressing pRNA to enable rRNA gene transcription and ribosomal biogenesis and that RNPI represents a target for tumor vessel normalization therapy of cancer.
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9
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Bryant CJ, McCool MA, Rosado-González GT, Abriola L, Surovtseva YV, Baserga SJ. Discovery of novel microRNA mimic repressors of ribosome biogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.17.526327. [PMID: 36824951 PMCID: PMC9949135 DOI: 10.1101/2023.02.17.526327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
While microRNAs and other non-coding RNAs are the next frontier of novel regulators of mammalian ribosome biogenesis (RB), a systematic exploration of microRNA-mediated RB regulation has not yet been undertaken. We carried out a high-content screen in MCF10A cells for changes in nucleolar number using a library of 2,603 mature human microRNA mimics. Following a secondary screen for nucleolar rRNA biogenesis inhibition, we identified 72 novel microRNA negative regulators of RB after stringent hit calling. Hits included 27 well-conserved microRNAs present in MirGeneDB, and were enriched for mRNA targets encoding proteins with nucleolar localization or functions in cell cycle regulation. Rigorous selection and validation of a subset of 15 microRNA hits unexpectedly revealed that most of them caused dysregulated pre-rRNA processing, elucidating a novel role for microRNAs in RB regulation. Almost all hits impaired global protein synthesis and upregulated CDKN1A ( p21 ) levels, while causing diverse effects on RNA Polymerase 1 (RNAP1) transcription and TP53 protein levels. We discovered that the MIR-28 siblings, hsa-miR-28-5p and hsa-miR-708-5p, directly and potently target the ribosomal protein mRNA RPS28 via tandem primate-specific 3' UTR binding sites, causing a severe pre-18S pre-rRNA processing defect. Our work illuminates novel microRNA attenuators of RB, forging a promising new path for microRNA mimic chemotherapeutics.
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10
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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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11
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Moss T, LeDoux MS, Crane-Robinson C. HMG-boxes, ribosomopathies and neurodegenerative disease. Front Genet 2023; 14:1225832. [PMID: 37600660 PMCID: PMC10435976 DOI: 10.3389/fgene.2023.1225832] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 07/19/2023] [Indexed: 08/22/2023] Open
Abstract
The UBTF E210K neuroregression syndrome is a predominantly neurological disorder caused by recurrent de novo dominant variants in Upstream Binding Factor, that is, essential for transcription of the ribosomal RNA genes. This unusual form of ribosomopathy is characterized by a slow decline in cognition, behavior, and sensorimotor functioning during the critical period of development. UBTF (or UBF) is a multi-HMGB-box protein that acts both as an epigenetic factor to establish "open" chromatin on the ribosomal genes and as a basal transcription factor in their RNA Polymerase I transcription. Here we review the possible mechanistic connections between the UBTF variants, ribosomal RNA gene transcription and the neuroregression syndrome, and suggest that DNA topology may play an important role.
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Affiliation(s)
- Tom Moss
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre, Québec, QC, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Québec, QC, Canada
| | - Mark S. LeDoux
- Department of Psychology, University of Memphis, Memphis, TN, United States
- Veracity Neuroscience LLC, Memphis, TN, United States
| | - Colyn Crane-Robinson
- Biophysics Laboratories, School of Biology, University of Portsmouth, Portsmouth, United Kingdom
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12
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Ni C, Buszczak M. The homeostatic regulation of ribosome biogenesis. Semin Cell Dev Biol 2023; 136:13-26. [PMID: 35440410 PMCID: PMC9569395 DOI: 10.1016/j.semcdb.2022.03.043] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 03/30/2022] [Accepted: 03/31/2022] [Indexed: 12/22/2022]
Abstract
The continued integrity of biological systems depends on a balance between interdependent elements at the molecular, cellular, and organismal levels. This is particularly true for the generation of ribosomes, which influence almost every aspect of cell and organismal biology. Ribosome biogenesis (RiBi) is an energetically demanding process that involves all three RNA polymerases, numerous RNA processing factors, chaperones, and the coordinated expression of 79-80 ribosomal proteins (r-proteins). Work over the last several decades has revealed that the dynamic regulation of ribosome production represents a major mechanism by which cells maintain homeostasis in response to changing environmental conditions and acute stress. More recent studies suggest that cells and tissues within multicellular organisms exhibit dramatically different levels of ribosome production and protein synthesis, marked by the differential expression of RiBi factors. Thus, distinct bottlenecks in the RiBi process, downstream of rRNA transcription, may exist within different cell populations of multicellular organisms during development and in adulthood. This review will focus on our current understanding of the mechanisms that link the complex molecular process of ribosome biogenesis with cellular and organismal physiology. We will discuss diverse topics including how different steps in the RiBi process are coordinated with one another, how MYC and mTOR impact RiBi, and how RiBi levels change between stem cells and their differentiated progeny. In turn, we will also review how regulated changes in ribosome production itself can feedback to influence cell fate and function.
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Affiliation(s)
- Chunyang Ni
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA
| | - Michael Buszczak
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9148, USA.
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13
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Miyake T, McDermott JC. Re-organization of nucleolar architecture in myogenic differentiation. J Cell Sci 2023; 136:286887. [PMID: 36727534 DOI: 10.1242/jcs.260496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 01/19/2023] [Indexed: 02/03/2023] Open
Abstract
Myogenesis, the process of muscle differentiation, requires an extensive remodeling of the cellular transcriptome and proteome. Whereas the transcriptional program underpinning myogenesis is well characterized, the required adaptation in protein synthesis is incompletely understood. Enhanced protein synthesis necessitates ribosome biogenesis at the nucleolus. Nucleolar size and activity are inextricably linked with altered gene expression. Here, we report changes in nucleolar morphology and function during myogenic differentiation. Immunofluorescence analysis revealed alterations in nucleolar morphology that were dependent on the cellular state - proliferative or quiescent myogenic progenitors (myoblasts or reserve cells) contained multiple small nucleoli with a characteristic spherical shape, whereas multinucleated myotubes typically contained one large, often irregularly shaped nucleolus. These morphological alterations are consistent with changes to nucleolar phase separation properties. Re-organization of the nucleolar structure was correlated with enhanced rRNA production and protein translation. Inhibition of mTOR signaling with rapamycin perturbed nucleolar re-organization. Conversely, hyperactivated mTOR enhanced alterations in nucleolar morphology. These findings support the idea that there is an mTOR dependent re-organization of nucleolar structure during myogenesis, enhancing our understanding of myogenesis and possibly facilitating new approaches to therapeutic interventions in muscle pathologies.
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Affiliation(s)
- Tetsuaki Miyake
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada.,Muscle Health Research Centre (MHRC), York University, Toronto, ON M3J 1P3, Canada.,Centre for Research in Biomolecular Interactions (CRBI), York University, Toronto, ON M3J 1P3, Canada
| | - John C McDermott
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada.,Muscle Health Research Centre (MHRC), York University, Toronto, ON M3J 1P3, Canada.,Centre for Research in Biomolecular Interactions (CRBI), York University, Toronto, ON M3J 1P3, Canada
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14
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Ballmer D, Tardat M, Ortiz R, Graff-Meyer A, Ozonov E, Genoud C, Peters A, Fanourgakis G. HP1 proteins regulate nucleolar structure and function by secluding pericentromeric constitutive heterochromatin. Nucleic Acids Res 2022; 51:117-143. [PMID: 36533441 PMCID: PMC9841413 DOI: 10.1093/nar/gkac1159] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Revised: 10/29/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Nucleoli are nuclear compartments regulating ribosome biogenesis and cell growth. In embryonic stem cells (ESCs), nucleoli containing transcriptionally active ribosomal genes are spatially separated from pericentromeric satellite repeat sequences packaged in largely repressed constitutive heterochromatin (PCH). To date, mechanisms underlying such nuclear partitioning and the physiological relevance thereof are unknown. Here we show that repressive chromatin at PCH ensures structural integrity and function of nucleoli during cell cycle progression. Loss of heterochromatin proteins HP1α and HP1β causes deformation of PCH, with reduced H3K9 trimethylation (H3K9me3) and HP1γ levels, absence of H4K20me3 and upregulated major satellites expression. Spatially, derepressed PCH aberrantly associates with nucleoli accumulating severe morphological defects during S/G2 cell cycle progression. Hp1α/β deficiency reduces cell proliferation, ribosomal RNA biosynthesis and mobility of Nucleophosmin, a major nucleolar component. Nucleolar integrity and function require HP1α/β proteins to be recruited to H3K9me3-marked PCH and their ability to dimerize. Correspondingly, ESCs deficient for both Suv39h1/2 H3K9 HMTs display similar nucleolar defects. In contrast, Suv4-20h1/2 mutant ESCs lacking H4K20me3 at PCH do not. Suv39h1/2 and Hp1α/β deficiency-induced nucleolar defects are reminiscent of those defining human ribosomopathy disorders. Our results reveal a novel role for SUV39H/HP1-marked repressive constitutive heterochromatin in regulating integrity, function and physiology of nucleoli.
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Affiliation(s)
- Daniel Ballmer
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland,Faculty of Sciences, University of Basel, 4056 Basel, Switzerland
| | - Mathieu Tardat
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Raphael Ortiz
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Alexandra Graff-Meyer
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Evgeniy A Ozonov
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Christel Genoud
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | | | - Grigorios Fanourgakis
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
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15
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Regulation of RNA Polymerase I Stability and Function. Cancers (Basel) 2022; 14:cancers14235776. [PMID: 36497261 PMCID: PMC9737084 DOI: 10.3390/cancers14235776] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 11/21/2022] [Accepted: 11/21/2022] [Indexed: 11/27/2022] Open
Abstract
RNA polymerase I is a highly processive enzyme with fast initiation and elongation rates. The structure of Pol I, with its in-built RNA cleavage ability and incorporation of subunits homologous to transcription factors, enables it to quickly and efficiently synthesize the enormous amount of rRNA required for ribosome biogenesis. Each step of Pol I transcription is carefully controlled. However, cancers have highjacked these control points to switch the enzyme, and its transcription, on permanently. While this provides an exceptional benefit to cancer cells, it also creates a potential cancer therapeutic vulnerability. We review the current research on the regulation of Pol I transcription, and we discuss chemical biology efforts to develop new targeted agents against this process. Lastly, we highlight challenges that have arisen from the introduction of agents with promiscuous mechanisms of action and provide examples of agents with specificity and selectivity against Pol I.
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16
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Antony C, George SS, Blum J, Somers P, Thorsheim CL, Wu-Corts DJ, Ai Y, Gao L, Lv K, Tremblay MG, Moss T, Tan K, Wilusz JE, Ganley ARD, Pimkin M, Paralkar VR. Control of ribosomal RNA synthesis by hematopoietic transcription factors. Mol Cell 2022; 82:3826-3839.e9. [PMID: 36113481 PMCID: PMC9588704 DOI: 10.1016/j.molcel.2022.08.027] [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: 01/21/2022] [Revised: 06/23/2022] [Accepted: 08/23/2022] [Indexed: 11/19/2022]
Abstract
Ribosomal RNAs (rRNAs) are the most abundant cellular RNAs, and their synthesis from rDNA repeats by RNA polymerase I accounts for the bulk of all transcription. Despite substantial variation in rRNA transcription rates across cell types, little is known about cell-type-specific factors that bind rDNA and regulate rRNA transcription to meet tissue-specific needs. Using hematopoiesis as a model system, we mapped about 2,200 ChIP-seq datasets for 250 transcription factors (TFs) and chromatin proteins to human and mouse rDNA and identified robust binding of multiple TF families to canonical TF motifs on rDNA. Using a 47S-FISH-Flow assay developed for nascent rRNA quantification, we demonstrated that targeted degradation of C/EBP alpha (CEBPA), a critical hematopoietic TF with conserved rDNA binding, caused rapid reduction in rRNA transcription due to reduced RNA Pol I occupancy. Our work identifies numerous potential rRNA regulators and provides a template for dissection of TF roles in rRNA transcription.
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Affiliation(s)
- Charles Antony
- Division of Hematology and Oncology, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Subin S George
- Institute for Biomedical Informatics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Justin Blum
- The College of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Patrick Somers
- Division of Hematology and Oncology, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Chelsea L Thorsheim
- Cardiovascular Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Dexter J Wu-Corts
- The College of Arts and Sciences, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Yuxi Ai
- Biochemistry and Molecular Biophysics Graduate Group, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Long Gao
- Beijing Advanced Innovation Center for Genomics (ICG) & Biomedical Pioneering Innovation Center (BIOPIC), Peking University, Beijing 100871, China
| | - Kaosheng Lv
- Division of Hematology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Biochemistry, School of Medicine, Southern University of Science and Technology, Shenzhen, China
| | - Michel G Tremblay
- Laboratory of Growth and Development, St Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre (CRCHU de Québec-Université Laval), Québec, QC G1R 3S3, Canada
| | - Tom Moss
- Laboratory of Growth and Development, St Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre (CRCHU de Québec-Université Laval), Québec, QC G1R 3S3, Canada; Department of Molecular Biology, Medical Biochemistry and Pathology, Laval University, Québec, QC G1V 0A6, Canada
| | - Kai Tan
- Department of Pediatrics, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Jeremy E Wilusz
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Therapeutic Innovation Center, Baylor College of Medicine, Houston, TX 77030, USA
| | - Austen R D Ganley
- School of Biological Sciences, University of Auckland, Auckland 0623, New Zealand; Digital Life Institute, University of Auckland, Auckland 0632, New Zealand
| | - Maxim Pimkin
- Cancer and Blood Disorders Center, Dana-Farber Cancer Institute and Boston Children's Hospital, Harvard Medical School, Boston, MA 02215, USA
| | - Vikram R Paralkar
- Division of Hematology and Oncology, Department of Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Department of Cell and Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Abramson Family Cancer Research Institute, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA.
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17
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Ball CB, Parida M, Li M, Spector BM, Suarez GA, Meier JL, Price DH. Human Cytomegalovirus Infection Elicits Global Changes in Host Transcription by RNA Polymerases I, II, and III. Viruses 2022; 14:v14040779. [PMID: 35458509 PMCID: PMC9026722 DOI: 10.3390/v14040779] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 03/29/2022] [Accepted: 03/30/2022] [Indexed: 12/29/2022] Open
Abstract
How human cytomegalovirus (HCMV) infection impacts the transcription of the host genome remains incompletely understood. Here, we examine the global consequences of infection of primary human foreskin fibroblasts (HFFs) on transcription by RNA polymerase I, II, and III over the course of a lytic infection using PRO-Seq. The expected rapid induction of innate immune response genes is observed with specific subsets of genes exhibiting dissimilar expression kinetics. We find minimal effects on Pol II initiation, but increased rates of the release of paused Pol II into productive elongation are detected by 24 h postinfection and pronounced at late times postinfection. Pol I transcription increases during infection and we provide evidence for a potential Pol I elongation control mechanism. Pol III transcription of tRNA genes is dramatically altered, with many induced and some repressed. All effects are partially dependent on viral genome replication, suggesting a link to viral mRNA levels and/or a viral early–late or late gene product. Changes in tRNA transcription are connected to distinct alterations in the chromatin state around tRNA genes, which were probed with high-resolution DFF-ChIP. Additionally, evidence is provided that the Pol III PIC stably contacts an upstream −1 nucleosome. Finally, we compared and contrasted our HCMV data with results from published experiments with HSV-1, EBV, KSHV, and MHV68. We report disparate effects on Pol II transcription and potentially similar effects on Pol III transcription.
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Affiliation(s)
- Christopher B. Ball
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA 52242, USA; (C.B.B.); (M.P.); (B.M.S.); (G.A.S.)
| | - Mrutyunjaya Parida
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA 52242, USA; (C.B.B.); (M.P.); (B.M.S.); (G.A.S.)
| | - Ming Li
- Departments of Internal Medicine and Epidemiology, University of Iowa and Iowa City Veterans Affairs Health Care System, Iowa City, IA 52242, USA; (M.L.); (J.L.M.)
| | - Benjamin M. Spector
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA 52242, USA; (C.B.B.); (M.P.); (B.M.S.); (G.A.S.)
| | - Gustavo A. Suarez
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA 52242, USA; (C.B.B.); (M.P.); (B.M.S.); (G.A.S.)
| | - Jeffery L. Meier
- Departments of Internal Medicine and Epidemiology, University of Iowa and Iowa City Veterans Affairs Health Care System, Iowa City, IA 52242, USA; (M.L.); (J.L.M.)
| | - David H. Price
- Department of Biochemistry and Molecular Biology, University of Iowa, Iowa City, IA 52242, USA; (C.B.B.); (M.P.); (B.M.S.); (G.A.S.)
- Correspondence:
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18
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Epigenetic regulation of human non-coding RNA gene transcription. Biochem Soc Trans 2022; 50:723-736. [PMID: 35285478 DOI: 10.1042/bst20210860] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 02/18/2022] [Accepted: 02/21/2022] [Indexed: 12/12/2022]
Abstract
Recent investigations on the non-protein-coding transcriptome of human cells have revealed previously hidden layers of gene regulation relying on regulatory non-protein-coding (nc) RNAs, including the widespread ncRNA-dependent regulation of epigenetic chromatin states and of mRNA translation and stability. However, despite its centrality, the epigenetic regulation of ncRNA genes has received relatively little attention. In this mini-review, we attempt to provide a synthetic account of recent literature suggesting an unexpected complexity in chromatin-dependent regulation of ncRNA gene transcription by the three human nuclear RNA polymerases. Emerging common features, like the heterogeneity of chromatin states within ncRNA multigene families and their influence on 3D genome organization, point to unexplored issues whose investigation could lead to a better understanding of the whole human epigenomic network.
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19
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Tremblay MG, Sibai DS, Valère M, Mars JC, Lessard F, Hori RT, Khan MM, Stefanovsky VY, LeDoux MS, Moss T. Ribosomal DNA promoter recognition is determined in vivo by cooperation between UBTF1 and SL1 and is compromised in the UBTF-E210K neuroregression syndrome. PLoS Genet 2022; 18:e1009644. [PMID: 35139074 PMCID: PMC8863233 DOI: 10.1371/journal.pgen.1009644] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 02/22/2022] [Accepted: 01/12/2022] [Indexed: 11/18/2022] Open
Abstract
Transcription of the ~200 mouse and human ribosomal RNA genes (rDNA) by RNA Polymerase I (RPI/PolR1) accounts for 80% of total cellular RNA, around 35% of all nuclear RNA synthesis, and determines the cytoplasmic ribosome complement. It is therefore a major factor controlling cell growth and its misfunction has been implicated in hypertrophic and developmental disorders. Activation of each rDNA repeat requires nucleosome replacement by the architectural multi-HMGbox factor UBTF to create a 15.7 kbp nucleosome free region (NFR). Formation of this NFR is also essential for recruitment of the TBP-TAFI factor SL1 and for preinitiation complex (PIC) formation at the gene and enhancer-associated promoters of the rDNA. However, these promoters show little sequence commonality and neither UBTF nor SL1 display significant DNA sequence binding specificity, making what drives PIC formation a mystery. Here we show that cooperation between SL1 and the longer UBTF1 splice variant generates the specificity required for rDNA promoter recognition in cell. We find that conditional deletion of the TAF1B subunit of SL1 causes a striking depletion of UBTF at both rDNA promoters but not elsewhere across the rDNA. We also find that while both UBTF1 and -2 variants bind throughout the rDNA NFR, only UBTF1 is present with SL1 at the promoters. The data strongly suggest an induced-fit model of RPI promoter recognition in which UBTF1 plays an architectural role. Interestingly, a recurrent UBTF-E210K mutation and the cause of a pediatric neurodegeneration syndrome provides indirect support for this model. E210K knock-in cells show enhanced levels of the UBTF1 splice variant and a concomitant increase in active rDNA copies. In contrast, they also display reduced rDNA transcription and promoter recruitment of SL1. We suggest the underlying cause of the UBTF-E210K syndrome is therefore a reduction in cooperative UBTF1-SL1 promoter recruitment that may be partially compensated by enhanced rDNA activation.
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Affiliation(s)
- Michel G. Tremblay
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre, Québec, Canada
| | - Dany S. Sibai
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre, Québec, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Québec, Canada
| | - Melissa Valère
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre, Québec, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Québec, Canada
| | - Jean-Clément Mars
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre, Québec, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Québec, Canada
| | - Frédéric Lessard
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre, Québec, Canada
| | | | - Mohammad Moshahid Khan
- Departments of Neurology and Anatomy & Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, United States of America
| | - Victor Y. Stefanovsky
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre, Québec, Canada
| | - Mark S. LeDoux
- Department of Psychology, University of Memphis, Memphis TN and Veracity Neuroscience LLC, Memphis, Tennessee, United States of America
| | - Tom Moss
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre, Québec, Canada
- Department of Molecular Biology, Medical Biochemistry and Pathology, Faculty of Medicine, Laval University, Québec, Canada
- * E-mail:
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20
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Chebrout M, Koné MC, Jan HU, Cournut M, Letheule M, Fleurot R, Aguirre-Lavin T, Peynot N, Jouneau A, Beaujean N, Bonnet-Garnier A. Transcription of rRNA in early mouse embryos promotes chromatin reorganization and expression of major satellite repeats. J Cell Sci 2022; 135:274059. [DOI: 10.1242/jcs.258798] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 01/09/2022] [Indexed: 11/20/2022] Open
Abstract
During the first cell cycles of the early development, the chromatin of the embryo is highly reprogrammed alongside that embryonic genome starts its own transcription. The spatial organization of the genome is a major process that contributes to regulating gene transcription in time and space, however, it is poorly studied in the context of early embryos. To study the cause and effect link between transcription and spatial organization in embryos, we focused on the ribosomal genes, that are first silent and begin to transcribe during the 2-cell stage in the mouse. We demonstrated that ribosomal sequences and early unprocessed rRNAs are spatially organized in a very peculiar manner from the 2-cell to the 16-cell. Using drugs interfering with ribosomal DNA transcription, we show that this organization, totally different from somatic cells, depends on an active transcription of ribosomal genes and induces a unique chromatin environment that favors transcription of major satellite sequences after the 4-cell stage.
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Affiliation(s)
- Martine Chebrout
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Maïmouna Coura Koné
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Habib U. Jan
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Marie Cournut
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Martine Letheule
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Renaud Fleurot
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Tiphaine Aguirre-Lavin
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Nathalie Peynot
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Alice Jouneau
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Nathalie Beaujean
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
| | - Amélie Bonnet-Garnier
- Université Paris-Saclay, UVSQ, INRAE, BREED, 78350, Jouy-en-Josas, France
- Ecole Nationale Vétérinaire d'Alfort, BREED, 94700, Maisons-Alfort, France
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21
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Merkl PE, Schächner C, Pilsl M, Schwank K, Schmid C, Längst G, Milkereit P, Griesenbeck J, Tschochner H. Specialization of RNA Polymerase I in Comparison to Other Nuclear RNA Polymerases of Saccharomyces cerevisiae. Methods Mol Biol 2022; 2533:63-70. [PMID: 35796982 PMCID: PMC9761553 DOI: 10.1007/978-1-0716-2501-9_4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In archaea and bacteria the major classes of RNAs are synthesized by one DNA-dependent RNA polymerase (RNAP). In contrast, most eukaryotes have three highly specialized RNAPs to transcribe the nuclear genome. RNAP I synthesizes almost exclusively ribosomal (r)RNA, RNAP II synthesizes mRNA as well as many noncoding RNAs involved in RNA processing or RNA silencing pathways and RNAP III synthesizes mainly tRNA and 5S rRNA. This review discusses functional differences of the three nuclear core RNAPs in the yeast S. cerevisiae with a particular focus on RNAP I transcription of nucleolar ribosomal (r)DNA chromatin.
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Affiliation(s)
- Philipp E Merkl
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
- TUM ForTe, Technische Universität München, Munich, Germany
| | - Christopher Schächner
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Michael Pilsl
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Katrin Schwank
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Catharina Schmid
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Gernot Längst
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Philipp Milkereit
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany.
| | - Joachim Griesenbeck
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Herbert Tschochner
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany.
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22
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Cockrell AJ, Gerton JL. Nucleolar Organizer Regions as Transcription-Based Scaffolds of Nucleolar Structure and Function. Results Probl Cell Differ 2022; 70:551-580. [PMID: 36348121 DOI: 10.1007/978-3-031-06573-6_19] [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: 06/16/2023]
Abstract
Eukaryotic genomes maintain multiple copies of ribosomal DNA gene repeats in tandem arrays to provide sufficient ribosomal RNAs to make ribosomes. These DNA repeats are the most highly transcribed regions of the genome, with dedicated transcriptional machinery to manage the enormous task of producing more than 50% of the total RNA in a proliferating cell. The arrays are called nucleolar organizer regions (NORs) and constitute the scaffold of the nucleolar compartment, where ribosome biogenesis occurs. Advances in molecular and cellular biology have brought great insights into how these arrays are transcribed and organized within genomes. Much of their biology is driven by their high transcription level, which has also driven the development of unique methods to understand rDNA gene activity, beginning with classic techniques such as silver staining and Miller spreads. However, the application of modern methodologies such as CRISPR gene editing, super-resolution microscopy, and long-read sequencing has enabled recent advances described herein, with many more discoveries possible soon. This chapter highlights what is known about NOR transcription and organization and the techniques applied historically and currently. Given the potential for NORs to impact organismal health and disease, as highlighted at the end of the chapter, the field must continue to develop and apply innovative analysis to understand genetic, epigenetic, and organizer properties of the ribosomal DNA repeats.
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Affiliation(s)
- Alexandria J Cockrell
- Stowers Institute for Medical Research, Kansas City, MO, USA
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA
| | - Jennifer L Gerton
- Stowers Institute for Medical Research, Kansas City, MO, USA.
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, KS, USA.
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23
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Schächner C, Merkl PE, Pilsl M, Schwank K, Hergert K, Kruse S, Milkereit P, Tschochner H, Griesenbeck J. Establishment and Maintenance of Open Ribosomal RNA Gene Chromatin States in Eukaryotes. Methods Mol Biol 2022; 2533:25-38. [PMID: 35796980 PMCID: PMC9761505 DOI: 10.1007/978-1-0716-2501-9_2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In growing eukaryotic cells, nuclear ribosomal (r)RNA synthesis by RNA polymerase (RNAP) I accounts for the vast majority of cellular transcription. This high output is achieved by the presence of multiple copies of rRNA genes in eukaryotic genomes transcribed at a high rate. In contrast to most of the other transcribed genomic loci, actively transcribed rRNA genes are largely devoid of nucleosomes adapting a characteristic "open" chromatin state, whereas a significant fraction of rRNA genes resides in a transcriptionally inactive nucleosomal "closed" chromatin state. Here, we review our current knowledge about the nature of open rRNA gene chromatin and discuss how this state may be established.
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Affiliation(s)
- Christopher Schächner
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Philipp E Merkl
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
- TUM ForTe, Technische Universität München, Munich, Germany
| | - Michael Pilsl
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Katrin Schwank
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Kristin Hergert
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Sebastian Kruse
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany
| | - Philipp Milkereit
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany.
| | - Herbert Tschochner
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany.
| | - Joachim Griesenbeck
- Universität Regensburg, Regensburg Center for Biochemistry (RCB), Lehrstuhl Biochemie III, Regensburg, Germany.
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24
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Tchurikov NA, Kravatsky YV. The Role of rDNA Clusters in Global Epigenetic Gene Regulation. Front Genet 2021; 12:730633. [PMID: 34531902 PMCID: PMC8438155 DOI: 10.3389/fgene.2021.730633] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 08/02/2021] [Indexed: 12/26/2022] Open
Abstract
The regulation of gene expression has been studied for decades, but the underlying mechanisms are still not fully understood. As well as local and distant regulation, there are specific mechanisms of regulation during development and physiological modulation of gene activity in differentiated cells. Current research strongly supports a role for the 3D chromosomal structure in the regulation of gene expression. However, it is not known whether the genome structure reflects the formation of active or repressed chromosomal domains or if these structures play a primary role in the regulation of gene expression. During early development, heterochromatinization of ribosomal DNA (rDNA) is coupled with silencing or activation of the expression of different sets of genes. Although the mechanisms behind this type of regulation are not known, rDNA clusters shape frequent inter-chromosomal contacts with a large group of genes controlling development. This review aims to shed light on the involvement of clusters of ribosomal genes in the global regulation of gene expression. We also discuss the possible role of RNA-mediated and phase-separation mechanisms in the global regulation of gene expression by nucleoli.
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Affiliation(s)
- Nickolai A Tchurikov
- Engelhardt Institute of Molecular Biology Russian Academy of Sciences, Moscow, Russia
| | - Yuri V Kravatsky
- Engelhardt Institute of Molecular Biology Russian Academy of Sciences, Moscow, Russia
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25
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Antagonising Chromatin Remodelling Activities in the Regulation of Mammalian Ribosomal Transcription. Genes (Basel) 2021; 12:genes12070961. [PMID: 34202617 PMCID: PMC8303148 DOI: 10.3390/genes12070961] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 06/16/2021] [Accepted: 06/19/2021] [Indexed: 12/29/2022] Open
Abstract
Ribosomal transcription constitutes the major energy consuming process in cells and is regulated in response to proliferation, differentiation and metabolic conditions by several signalling pathways. These act on the transcription machinery but also on chromatin factors and ncRNA. The many ribosomal gene repeats are organised in a number of different chromatin states; active, poised, pseudosilent and repressed gene repeats. Some of these chromatin states are unique to the 47rRNA gene repeat and do not occur at other locations in the genome, such as the active state organised with the HMG protein UBF whereas other chromatin state are nucleosomal, harbouring both active and inactive histone marks. The number of repeats in a certain state varies on developmental stage and cell type; embryonic cells have more rRNA gene repeats organised in an open chromatin state, which is replaced by heterochromatin during differentiation, establishing different states depending on cell type. The 47S rRNA gene transcription is regulated in different ways depending on stimulus and chromatin state of individual gene repeats. This review will discuss the present knowledge about factors involved, such as chromatin remodelling factors NuRD, NoRC, CSB, B-WICH, histone modifying enzymes and histone chaperones, in altering gene expression and switching chromatin states in proliferation, differentiation, metabolic changes and stress responses.
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26
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The Ribosomal Gene Loci-The Power behind the Throne. Genes (Basel) 2021; 12:genes12050763. [PMID: 34069807 PMCID: PMC8157237 DOI: 10.3390/genes12050763] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/12/2021] [Accepted: 05/14/2021] [Indexed: 12/20/2022] Open
Abstract
Nucleoli form around actively transcribed ribosomal RNA (rRNA) genes (rDNA), and the morphology and location of nucleolus-associated genomic domains (NADs) are linked to the RNA Polymerase I (Pol I) transcription status. The number of rDNA repeats (and the proportion of actively transcribed rRNA genes) is variable between cell types, individuals and disease state. Substantial changes in nucleolar morphology and size accompanied by concomitant changes in the Pol I transcription rate have long been documented during normal cell cycle progression, development and malignant transformation. This demonstrates how dynamic the nucleolar structure can be. Here, we will discuss how the structure of the rDNA loci, the nucleolus and the rate of Pol I transcription are important for dynamic regulation of global gene expression and genome stability, e.g., through the modulation of long-range genomic interactions with the suppressive NAD environment. These observations support an emerging paradigm whereby the rDNA repeats and the nucleolus play a key regulatory role in cellular homeostasis during normal development as well as disease, independent of their role in determining ribosome capacity and cellular growth rates.
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27
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Poot M, Hochstenbach R. Prevalence and Phenotypic Impact of Robertsonian Translocations. Mol Syndromol 2021; 12:1-11. [PMID: 33776621 PMCID: PMC7983559 DOI: 10.1159/000512676] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 10/26/2020] [Indexed: 12/11/2022] Open
Abstract
Robertsonian translocations (RTs) result from fusion of 2 acrocentric chromosomes (e.g., 13, 14, 15, 21, 22) and consequential losses of segments of the p arms containing 47S rDNA clusters and transcription factor binding sites. Depending on the position of the breakpoints, the size of these losses vary considerably between types of RTs. The prevalence of RTs in the general population is estimated to be around 1 per 800 individuals, making RTs the most common chromosomal rearrangement in healthy individuals. Based on their prevalence, RTs are classified as "common," rob(13;14) and rob(14;21), or "rare" (the 8 remaining nonhomologous combinations). Carriers of RTs are at an increased risk for offspring with chromosomal imbalances or with uniparental disomy. RTs are generally regarded as phenotypically neutral, although, due to RTs formation, 2 of the 10 ribosomal rDNA gene clusters, several long noncoding RNAs, and in the case of RTs involving chromosome 21, several mRNA encoding genes are lost. Nevertheless, recent evidence indicates that RTs may have a significant phenotypic impact. In particular, rob(13;14) carriers have a significantly elevated risk for breast cancer. While RTs are easily spotted by routine karyotyping, they may go unnoticed if only array-CGH and NextGen sequencing methods are applied. This review first discusses possible molecular mechanisms underlying the particularly high rates of RT formation and their incidence in the general population, and second, likely causes for the elevated cancer risk of some RTs will be examined.
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Affiliation(s)
- Martin Poot
- Department of Human Genetics, University of Würzburg, Würzburg, Germany
| | - Ron Hochstenbach
- Department of Clinical Genetics, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
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The Role of TCOF1 Gene in Health and Disease: Beyond Treacher Collins Syndrome. Int J Mol Sci 2021; 22:ijms22052482. [PMID: 33804586 PMCID: PMC7957619 DOI: 10.3390/ijms22052482] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 02/23/2021] [Accepted: 02/24/2021] [Indexed: 12/23/2022] Open
Abstract
The nucleoli are membrane-less nuclear substructures that govern ribosome biogenesis and participate in multiple other cellular processes such as cell cycle progression, stress sensing, and DNA damage response. The proper functioning of these organelles is ensured by specific proteins that maintain nucleolar structure and mediate key nucleolar activities. Among all nucleolar proteins, treacle encoded by TCOF1 gene emerges as one of the most crucial regulators of cellular processes. TCOF1 was initially discovered as a gene involved in the Treacher Collins syndrome, a rare genetic disorder characterized by severe craniofacial deformations. Later studies revealed that treacle regulates ribosome biogenesis, mitosis, proliferation, DNA damage response, and apoptosis. Importantly, several reports indicate that treacle is also involved in cancer development, progression, and response to therapies, and may contribute to other pathologies such as Hirschsprung disease. In this manuscript, we comprehensively review the structure, function, and the regulation of TCOF1/treacle in physiological and pathological processes.
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29
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Smirnov E, Chmúrčiaková N, Liška F, Bažantová P, Cmarko D. Variability of Human rDNA. Cells 2021; 10:cells10020196. [PMID: 33498263 PMCID: PMC7909238 DOI: 10.3390/cells10020196] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 01/18/2021] [Accepted: 01/19/2021] [Indexed: 12/15/2022] Open
Abstract
In human cells, ribosomal DNA (rDNA) is arranged in ten clusters of multiple tandem repeats. Each repeat is usually described as consisting of two parts: the 13 kb long ribosomal part, containing three genes coding for 18S, 5.8S and 28S RNAs of the ribosomal particles, and the 30 kb long intergenic spacer (IGS). However, this standard scheme is, amazingly, often altered as a result of the peculiar instability of the locus, so that the sequence of each repeat and the number of the repeats in each cluster are highly variable. In the present review, we discuss the causes and types of human rDNA instability, the methods of its detection, its distribution within the locus, the ways in which it is prevented or reversed, and its biological significance. The data of the literature suggest that the variability of the rDNA is not only a potential cause of pathology, but also an important, though still poorly understood, aspect of the normal cell physiology.
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30
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RNA Metabolism Guided by RNA Modifications: The Role of SMUG1 in rRNA Quality Control. Biomolecules 2021; 11:biom11010076. [PMID: 33430019 PMCID: PMC7826747 DOI: 10.3390/biom11010076] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/29/2020] [Accepted: 01/05/2021] [Indexed: 12/19/2022] Open
Abstract
RNA modifications are essential for proper RNA processing, quality control, and maturation steps. In the last decade, some eukaryotic DNA repair enzymes have been shown to have an ability to recognize and process modified RNA substrates and thereby contribute to RNA surveillance. Single-strand-selective monofunctional uracil-DNA glycosylase 1 (SMUG1) is a base excision repair enzyme that not only recognizes and removes uracil and oxidized pyrimidines from DNA but is also able to process modified RNA substrates. SMUG1 interacts with the pseudouridine synthase dyskerin (DKC1), an enzyme essential for the correct assembly of small nucleolar ribonucleoproteins (snRNPs) and ribosomal RNA (rRNA) processing. Here, we review rRNA modifications and RNA quality control mechanisms in general and discuss the specific function of SMUG1 in rRNA metabolism. Cells lacking SMUG1 have elevated levels of immature rRNA molecules and accumulation of 5-hydroxymethyluridine (5hmU) in mature rRNA. SMUG1 may be required for post-transcriptional regulation and quality control of rRNAs, partly by regulating rRNA and stability.
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31
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Gupta S, Santoro R. Regulation and Roles of the Nucleolus in Embryonic Stem Cells: From Ribosome Biogenesis to Genome Organization. Stem Cell Reports 2020; 15:1206-1219. [PMID: 32976768 PMCID: PMC7724472 DOI: 10.1016/j.stemcr.2020.08.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 08/25/2020] [Accepted: 08/25/2020] [Indexed: 12/13/2022] Open
Abstract
The nucleolus is the largest compartment of the eukaryotic cell's nucleus. It acts as a ribosome factory, thereby sustaining the translation machinery. The nucleolus is also the subnuclear compartment with the highest transcriptional activity in the cell, where hundreds of ribosomal RNA (rRNA) genes transcribe the overwhelming majority of RNAs. The structure and composition of the nucleolus change according to the developmental state. For instance, in embryonic stem cells (ESCs), rRNA genes display a hyperactive transcriptional state and open chromatin structure compared with differentiated cells. Increasing evidence indicates that the role of the nucleolus and rRNA genes might go beyond the control of ribosome biogenesis. One such role is linked to the genome architecture, since repressive domains are often located close to the nucleolus. This review highlights recent findings describing how the nucleolus is regulated in ESCs and its role in regulating ribosome biogenesis and genome organization for the maintenance of stem cell identity.
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Affiliation(s)
- Shivani Gupta
- Department of Molecular Mechanisms of Disease, DMMD, University of Zurich, 8057 Zurich, Switzerland
| | - Raffaella Santoro
- Department of Molecular Mechanisms of Disease, DMMD, University of Zurich, 8057 Zurich, Switzerland.
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32
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Mars JC, Tremblay MG, Valere M, Sibai DS, Sabourin-Felix M, Lessard F, Moss T. The chemotherapeutic agent CX-5461 irreversibly blocks RNA polymerase I initiation and promoter release to cause nucleolar disruption, DNA damage and cell inviability. NAR Cancer 2020; 2:zcaa032. [PMID: 33196044 PMCID: PMC7646227 DOI: 10.1093/narcan/zcaa032] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 10/13/2020] [Accepted: 10/20/2020] [Indexed: 01/02/2023] Open
Abstract
In the search for drugs to effectively treat cancer, the last 10 years have seen a resurgence of interest in targeting ribosome biogenesis. CX-5461 is a potential inhibitor of ribosomal RNA synthesis that is now showing promise in phase I trials as a chemotherapeutic agent for a range of malignancies. Here, we show that CX-5461 irreversibly inhibits ribosomal RNA transcription by arresting RNA polymerase I (RPI/Pol1/PolR1) in a transcription initiation complex. CX-5461 does not achieve this by preventing formation of the pre-initiation complex nor does it affect the promoter recruitment of the SL1 TBP complex or the HMGB-box upstream binding factor (UBF/UBTF). CX-5461 also does not prevent the subsequent recruitment of the initiation-competent RPI–Rrn3 complex. Rather, CX-5461 blocks promoter release of RPI–Rrn3, which remains irreversibly locked in the pre-initiation complex even after extensive drug removal. Unexpectedly, this results in an unproductive mode of RPI recruitment that correlates with the onset of nucleolar stress, inhibition of DNA replication, genome-wide DNA damage and cellular senescence. Our data demonstrate that the cytotoxicity of CX-5461 is at least in part the result of an irreversible inhibition of RPI transcription initiation and hence are of direct relevance to the design of improved strategies of chemotherapy.
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Affiliation(s)
- Jean-Clément Mars
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre (CRCHU de Québec-Université Laval), Québec, QC, G1R 3S3, Canada
| | - Michel G Tremblay
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre (CRCHU de Québec-Université Laval), Québec, QC, G1R 3S3, Canada
| | - Mélissa Valere
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre (CRCHU de Québec-Université Laval), Québec, QC, G1R 3S3, Canada
| | - Dany S Sibai
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre (CRCHU de Québec-Université Laval), Québec, QC, G1R 3S3, Canada
| | - Marianne Sabourin-Felix
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre (CRCHU de Québec-Université Laval), Québec, QC, G1R 3S3, Canada
| | - Frédéric Lessard
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre (CRCHU de Québec-Université Laval), Québec, QC, G1R 3S3, Canada
| | - Tom Moss
- Laboratory of Growth and Development, St-Patrick Research Group in Basic Oncology, Cancer Division of the Quebec University Hospital Research Centre (CRCHU de Québec-Université Laval), Québec, QC, G1R 3S3, Canada
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Son J, Hannan KM, Poortinga G, Hein N, Cameron DP, Ganley ARD, Sheppard KE, Pearson RB, Hannan RD, Sanij E. rDNA Chromatin Activity Status as a Biomarker of Sensitivity to the RNA Polymerase I Transcription Inhibitor CX-5461. Front Cell Dev Biol 2020; 8:568. [PMID: 32719798 PMCID: PMC7349920 DOI: 10.3389/fcell.2020.00568] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 06/15/2020] [Indexed: 12/13/2022] Open
Abstract
Hyperactivation of RNA polymerase I (Pol I) transcription of ribosomal RNA (rRNA) genes (rDNA) is a key determinant of growth and proliferation and a consistent feature of cancer cells. We have demonstrated that inhibition of rDNA transcription by the Pol I transcription inhibitor CX-5461 selectively kills tumor cells in vivo. Moreover, the first-in human trial of CX-5461 has demonstrated CX-5461 is well-tolerated in patients and has single-agent anti-tumor activity in hematologic malignancies. However, the mechanisms underlying tumor cell sensitivity to CX-5461 remain unclear. Understanding these mechanisms is crucial for the development of predictive biomarkers of response that can be utilized for stratifying patients who may benefit from CX-5461. The rDNA repeats exist in four different and dynamic chromatin states: inactive rDNA can be either methylated silent or unmethylated pseudo-silent; while active rDNA repeats are described as either transcriptionally competent but non-transcribed or actively transcribed, depending on the level of rDNA promoter methylation, loading of the essential rDNA chromatin remodeler UBF and histone marks status. In addition, the number of rDNA repeats per human cell can reach hundreds of copies. Here, we tested the hypothesis that the number and/or chromatin status of the rDNA repeats, is a critical determinant of tumor cell sensitivity to Pol I therapy. We systematically examined a panel of ovarian cancer (OVCA) cell lines to identify rDNA chromatin associated biomarkers that might predict sensitivity to CX-5461. We demonstrated that an increased proportion of active to inactive rDNA repeats, independent of rDNA copy number, determines OVCA cell line sensitivity to CX-5461. Further, using zinc finger nuclease genome editing we identified that reducing rDNA copy number leads to an increase in the proportion of active rDNA repeats and confers sensitivity to CX-5461 but also induces genome-wide instability and sensitivity to DNA damage. We propose that the proportion of active to inactive rDNA repeats may serve as a biomarker to identify cancer patients who will benefit from CX-5461 therapy in future clinical trials. The data also reinforces the notion that rDNA instability is a threat to genomic integrity and cellular homeostasis.
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Affiliation(s)
- Jinbae Son
- Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, VIC, Australia
| | - Katherine M. Hannan
- ACRF Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, VIC, Australia
| | - Gretchen Poortinga
- Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, VIC, Australia
- Department of Medicine, St. Vincent’s Hospital, The University of Melbourne, Parkville, VIC, Australia
| | - Nadine Hein
- ACRF Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Donald P. Cameron
- ACRF Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
| | - Austen R. D. Ganley
- School of Biological Sciences, The University of Auckland, Auckland, New Zealand
| | - Karen E. Sheppard
- Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, VIC, Australia
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, VIC, Australia
| | - Richard B. Pearson
- Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, VIC, Australia
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, VIC, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
| | - Ross D. Hannan
- Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, VIC, Australia
- ACRF Department of Cancer Biology and Therapeutics, The John Curtin School of Medical Research, Australian National University, Canberra, ACT, Australia
- Department of Biochemistry and Molecular Biology, The University of Melbourne, Parkville, VIC, Australia
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
- School of Biomedical Sciences, The University of Queensland, Brisbane, QLD, Australia
| | - Elaine Sanij
- Peter MacCallum Cancer Centre, Melbourne, VIC, Australia
- Sir Peter MacCallum Department of Oncology, The University of Melbourne, Parkville, VIC, Australia
- Department of Clinical Pathology, The University of Melbourne, Parkville, VIC, Australia
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Rolicka A, Guo Y, Gañez Zapater A, Tariq K, Quin J, Vintermist A, Sadeghifar F, Arsenian-Henriksson M, Östlund Farrants AK. The chromatin-remodeling complexes B-WICH and NuRD regulate ribosomal transcription in response to glucose. FASEB J 2020; 34:10818-10834. [PMID: 32598531 DOI: 10.1096/fj.202000411r] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/26/2020] [Accepted: 06/04/2020] [Indexed: 12/20/2022]
Abstract
Regulation of ribosomal transcription is under tight control from environmental stimuli, and this control involves changes in the chromatin structure. The underlying mechanism of how chromatin changes in response to nutrient and energy supply in the cell is still unclear. The chromatin-remodeling complex B-WICH is involved in activating the ribosomal transcription, and we show here that knock down of the B-WICH component WSTF results in cells that do not respond to glucose. The promoter is less accessible, and RNA pol I and its transcription factors SL1/TIF-1B and RRN3/TIF-1A, as well as the proto-oncogene c-MYC and the activating deacetylase SIRT7 do not bind upon glucose stimulation. In contrast, the repressive chromatin state that forms after glucose deprivation is reversible, and RNA pol I factors are recruited. WSTF knock down results in an accumulation of the ATPase CHD4, a component of the NuRD chromatin remodeling complex, which is responsible for establishing a repressive poised state at the promoter. The TTF-1, which binds and affect the binding of the chromatin complexes, is important to control the association of activating chromatin component UBF. We suggest that B-WICH is required to allow for a shift to an active chromatin state upon environmental stimulation, by counteracting the repressive state induced by the NuRD complex.
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Affiliation(s)
- Anna Rolicka
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
| | - Yuan Guo
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
| | - Antoni Gañez Zapater
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
| | - Kanwal Tariq
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
| | - Jaclyn Quin
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
| | - Anna Vintermist
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
| | - Fatemeh Sadeghifar
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
| | - Marie Arsenian-Henriksson
- Department of Microbiology, Tumor and Cell Biology (MTC), Biomedicum B7, Karolinska Institutet, Stockholm, Sweden
| | - Ann-Kristin Östlund Farrants
- Department of Molecular Biosciences, The Wenner-Gren Institute, The Arrhenius Lab F4, Stockholm University, Stockholm, Sweden
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Smirnov E, Trosan P, Cabral JV, Studeny P, Kereïche S, Jirsova K, Cmarko D. Discontinuous transcription of ribosomal DNA in human cells. PLoS One 2020; 15:e0223030. [PMID: 32119673 PMCID: PMC7051091 DOI: 10.1371/journal.pone.0223030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 01/24/2020] [Indexed: 11/18/2022] Open
Abstract
Numerous studies show that various genes in all kinds of organisms are transcribed discontinuously, i.e. in short bursts or pulses with periods of inactivity between them. But it remains unclear whether ribosomal DNA (rDNA), represented by multiple copies in every cell, is also expressed in such manner. In this work, we synchronized the pol I activity in the populations of tumour derived as well as normal human cells by cold block and release. Our experiments with 5-fluorouridine (FU) and BrUTP confirmed that the nucleolar transcription can be efficiently and reversibly arrested at +4°C. Then using special software for analysis of the microscopic images, we measured the intensity of transcription signal (incorporated FU) in the nucleoli at different time points after the release. We found that the ribosomal genes in the human cells are transcribed discontinuously with periods ranging from 45 min to 75 min. Our data indicate that the dynamics of rDNA transcription follows the undulating pattern, in which the bursts are alternated by periods of rare transcription events.
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Affiliation(s)
- Evgeny Smirnov
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
- * E-mail:
| | - Peter Trosan
- Laboratory of the Biology and Pathology of the Eye, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Joao Victor Cabral
- Laboratory of the Biology and Pathology of the Eye, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Pavel Studeny
- Ophthalmology Department of 3rd Faculty of Medicine, Charles University and University Hospital Kralovske Vinohrady, Prague, Czech Republic
| | - Sami Kereïche
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Katerina Jirsova
- Laboratory of the Biology and Pathology of the Eye, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
| | - Dušan Cmarko
- Laboratory of Cell Biology, Institute of Biology and Medical Genetics, First Faculty of Medicine, Charles University and General University Hospital in Prague, Prague, Czech Republic
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Tchelidze P, Kaplan H, Terryn C, Lalun N, Ploton D, Thiry M. Electron tomography reveals changes in spatial distribution of UBTF1 and UBTF2 isoforms within nucleolar components during rRNA synthesis inhibition. J Struct Biol 2019; 208:191-204. [PMID: 31479756 DOI: 10.1016/j.jsb.2019.08.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 08/29/2019] [Accepted: 08/30/2019] [Indexed: 12/01/2022]
Abstract
Upstream binding transcription factor (UBTF) is a co-regulator of RNA polymerase I by constituting an initiation complex on rRNA genes. UBTF plays a role in rDNA bending and its maintenance in "open" state. It exists as two splicing variants, UBTF1 and UBTF2, which cannot be discerned with antibodies raised against UBTF. We investigated the ultrastructural localization of each variant in cells synthesizing GFP-tagged UBTF1 or UBTF2 by using anti-GFP antibodies and pre-embedding nanogold strategy. Detailed 3D distribution of UBTF1 and 2 was also studied by electron tomography. In control cells, the two isoforms are very abundant within fibrillar centers, but their repartition strongly differs. Electron tomography shows that UBTF1 is disposed as fibrils that are folded in coils whereas UBTF2 is localized homogenously, preferentially at their cortical area. As UBTF is a useful marker to trace rDNA genes, we used these data to improve our previous model of 3D organization of active transcribing rDNA gene within fibrillar centers. Finally, when rRNA synthesis is inhibited during actinomycin D treatment or entry in mitosis, UBTF1 and UBTF2 show a similar distribution along extended 3D loop-like structures. Altogether these data suggest new roles for UBTF1 and UBTF2 isoforms in the organization of active and inactive rDNA genes.
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Affiliation(s)
- Pavel Tchelidze
- Faculty of Health, Eastern European University, Tbilisi, Georgia
| | - Hervé Kaplan
- Université de Reims Champagne Ardenne, Reims, France
| | - Christine Terryn
- Platform of Cellular and Tissular Imaging (PICT), Université de Reims Champagne Ardenne, Reims, France
| | - Nathalie Lalun
- UMR-S 1250 INSERM, Université de Reims Champagne Ardenne, France
| | - Dominique Ploton
- BioSpecT, EA 7506, Université de Reims Champagne Ardenne, France
| | - Marc Thiry
- Unit of Cell and Tissue Biology, GIGA-Neurosciences, University of Liège, Liège, Belgium.
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Scull CE, Schneider DA. Coordinated Control of rRNA Processing by RNA Polymerase I. Trends Genet 2019; 35:724-733. [PMID: 31358304 DOI: 10.1016/j.tig.2019.07.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 06/25/2019] [Accepted: 07/01/2019] [Indexed: 11/19/2022]
Abstract
Ribosomal RNA (rRNA) is co- and post-transcriptionally processed into active ribosomes. This process is dynamically regulated by direct covalent modifications of the polymerase that synthesizes the rRNA, RNA polymerase I (Pol I), and by interactions with cofactors that influence initiation, elongation, and termination activities of Pol I. The rate of transcription elongation by Pol I directly influences processing of nascent rRNA, and changes in Pol I transcription rate result in alternative rRNA processing events that lead to cellular signaling alterations and stress. It is clear that in divergent species, there exists robust organization of nascent rRNA processing events during transcription elongation. This review evaluates the current state of our understanding of the complex relationship between transcription elongation and rRNA processing.
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Affiliation(s)
- Catherine E Scull
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - David A Schneider
- Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
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38
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Life time of some RNA products of rDNA intergenic spacer in HeLa cells. Histochem Cell Biol 2019; 152:271-280. [DOI: 10.1007/s00418-019-01804-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/15/2019] [Indexed: 12/21/2022]
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Kresoja-Rakic J, Santoro R. Nucleolus and rRNA Gene Chromatin in Early Embryo Development. Trends Genet 2019; 35:868-879. [PMID: 31327501 DOI: 10.1016/j.tig.2019.06.005] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/17/2019] [Accepted: 06/24/2019] [Indexed: 12/16/2022]
Abstract
The nucleolus is the largest substructure in the nucleus and forms around the nucleolar organizer regions (NORs), which comprise hundreds of rRNA genes. Recent evidence highlights further functions of the nucleolus that go beyond ribosome biogenesis. Data indicate that the nucleolus acts as a compartment for the location and regulation of repressive genomic domains and, together with the nuclear lamina, represents the hub for the organization of the inactive heterochromatin. In this review, we discuss recent findings that have revealed how nucleolar structure and rRNA gene chromatin states are regulated during early mammalian development and their contribution to the higher-order spatial organization of the genome.
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Affiliation(s)
- Jelena Kresoja-Rakic
- Department of Molecular Mechanisms of Disease, DMMD, University of Zurich, CH-8057 Zurich, Switzerland
| | - Raffaella Santoro
- Department of Molecular Mechanisms of Disease, DMMD, University of Zurich, CH-8057 Zurich, Switzerland.
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Pirogov SA, Gvozdev VA, Klenov MS. Long Noncoding RNAs and Stress Response in the Nucleolus. Cells 2019; 8:cells8070668. [PMID: 31269716 PMCID: PMC6678565 DOI: 10.3390/cells8070668] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 06/28/2019] [Accepted: 07/01/2019] [Indexed: 12/15/2022] Open
Abstract
Long noncoding RNAs (lncRNAs) perform diverse functions in the regulation of cellular processes. Here we consider a variety of lncRNAs found in the ribosome production center, the nucleolus, and focus on their role in the response to environmental stressors. Nucleolar lncRNAs ensure stress adaptation by cessation of resource-intensive ribosomal RNA (rRNA) synthesis and by inducing the massive sequestration of proteins within the nucleolus. Different cell states like quiescence and cancer are also controlled by specific lncRNAs in the nucleolus. Taken together, recent findings allow us to consider lncRNAs as multifunctional regulators of nucleolar activities, which are responsive to various physiological conditions.
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Affiliation(s)
- Sergei A Pirogov
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., 123182 Moscow, Russia
| | - Vladimir A Gvozdev
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., 123182 Moscow, Russia.
| | - Mikhail S Klenov
- Institute of Molecular Genetics, Russian Academy of Sciences, 2 Kurchatov Sq., 123182 Moscow, Russia.
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Genome Organization in and around the Nucleolus. Cells 2019; 8:cells8060579. [PMID: 31212844 PMCID: PMC6628108 DOI: 10.3390/cells8060579] [Citation(s) in RCA: 71] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 06/09/2019] [Accepted: 06/11/2019] [Indexed: 12/17/2022] Open
Abstract
The nucleolus is the largest substructure in the nucleus, where ribosome biogenesis takes place, and forms around the nucleolar organizer regions (NORs) that comprise ribosomal RNA (rRNA) genes. Each cell contains hundreds of rRNA genes, which are organized in three distinct chromatin and transcriptional states—silent, inactive and active. Increasing evidence indicates that the role of the nucleolus and rRNA genes goes beyond the control of ribosome biogenesis. Recent results highlighted the nucleolus as a compartment for the location and regulation of repressive genomic domains and, together with the nuclear lamina, represents the hub for the organization of the inactive heterochromatin. In this review, we aim to describe the crosstalk between the nucleolus and the rest of the genome and how distinct rRNA gene chromatin states affect nucleolus structure and are implicated in genome stability, genome architecture, and cell fate decision.
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