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Sharp JA, Sparago E, Thomas R, Alimenti K, Wang W, Blower MD. Role of the SAF-A SAP domain in X inactivation, transcription, splicing, and cell proliferation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.09.612041. [PMID: 39314300 PMCID: PMC11419091 DOI: 10.1101/2024.09.09.612041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 09/25/2024]
Abstract
SAF-A is conserved throughout vertebrates and has emerged as an important factor regulating a multitude of nuclear functions, including lncRNA localization, gene expression, and splicing. SAF-A has several functional domains, including an N-terminal SAP domain that binds directly to DNA. Phosphorylation of SAP domain serines S14 and S26 are important for SAF-A localization and function during mitosis, however whether these serines are involved in interphase functions of SAF-A is not known. In this study we tested for the role of the SAP domain, and SAP domain serines S14 and S26 in X chromosome inactivation, protein dynamics, gene expression, splicing, and cell proliferation. Here we show that the SAP domain serines S14 and S26 are required to maintain XIST RNA localization and polycomb-dependent histone modifications on the inactive X chromosome in female cells. In addition, we present evidence that an Xi localization signal resides in the SAP domain. We found that that the SAP domain is not required to maintain gene expression and plays only a minor role in mRNA splicing. In contrast, the SAF-A SAP domain, in particular serines S14 and S26, are required for normal protein dynamics, and to maintain normal cell proliferation. We propose a model whereby dynamic phosphorylation of SAF-A serines S14 and S26 mediates rapid turnover of SAF-A interactions with DNA during interphase.
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2
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Fan L, Sun W, Lyu Y, Ju F, Sun W, Chen J, Ma H, Yang S, Zhou X, Wu N, Yi W, Chen E, Villaseñor R, Baubec T, Yan J. Chrom-seq identifies RNAs at chromatin marks. SCIENCE ADVANCES 2024; 10:eadn1397. [PMID: 39083617 PMCID: PMC11290522 DOI: 10.1126/sciadv.adn1397] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 06/25/2024] [Indexed: 08/02/2024]
Abstract
Chromatin marks are associated with transcriptional regulatory activities. However, very few lncRNAs have been characterized with the role in regulating epigenetic marks, largely due to the technical difficulty in identifying chromatin-associating RNA. Current methods are largely limited by the availability of ChIP-grade antibody and the crosslinking, which generates high noise. Here, we developed a method termed Chrom-seq to efficiently capture RNAs associated with various chromatin marks in living cells. Chrom-seq jointly applies highly specific chromatin mark reader with APEX2, which catalyzes the oxidation of biotin-aniline to label the adjacent RNAs for isolation by streptavidin-coated beads. Using the readers of mCBX7/dPC, mCBX1, and mTAF3, we detected RNA species significantly associated with H3K27me3, H3K9me3, and H3K4me3, respectively. We demonstrated that Chrom-seq outperformed other equivalent methods in terms of sensitivity, efficiency, and cost of practice. It provides an antibody-free approach to systematically map RNAs at chromatin marks with potential regulatory roles in epigenetic events.
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Affiliation(s)
- Ligang Fan
- Ministry of Education Key Laboratory of Resource Biology and Biotechnology in Western China; Shaanxi Provincial Key Laboratory of Biotechnology; School of Medicine, Northwest University, Xi’an, China
- Department of Biomedical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences; The Tung Biomedical Sciences Centre, City University of Hong Kong, Hong Kong SAR, China
| | | | - Yitong Lyu
- Department of Biomedical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences; The Tung Biomedical Sciences Centre, City University of Hong Kong, Hong Kong SAR, China
| | - Furong Ju
- Department of Biomedical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences; The Tung Biomedical Sciences Centre, City University of Hong Kong, Hong Kong SAR, China
- Ming Wai Lau Centre for Reparative Medicine, Karolinska Institutet, Hong Kong SAR, China
| | - Wenju Sun
- Ministry of Education Key Laboratory of Resource Biology and Biotechnology in Western China; Shaanxi Provincial Key Laboratory of Biotechnology; School of Medicine, Northwest University, Xi’an, China
| | - Jie Chen
- Department of Biomedical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences; The Tung Biomedical Sciences Centre, City University of Hong Kong, Hong Kong SAR, China
| | - Haiqian Ma
- Ministry of Education Key Laboratory of Resource Biology and Biotechnology in Western China; Shaanxi Provincial Key Laboratory of Biotechnology; School of Medicine, Northwest University, Xi’an, China
| | - Shifei Yang
- Ministry of Education Key Laboratory of Resource Biology and Biotechnology in Western China; Shaanxi Provincial Key Laboratory of Biotechnology; School of Medicine, Northwest University, Xi’an, China
| | - Xiaomin Zhou
- Department of Biomedical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences; The Tung Biomedical Sciences Centre, City University of Hong Kong, Hong Kong SAR, China
| | - Nan Wu
- Ministry of Education Key Laboratory of Resource Biology and Biotechnology in Western China; Shaanxi Provincial Key Laboratory of Biotechnology; School of Medicine, Northwest University, Xi’an, China
- Department of Biomedical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences; The Tung Biomedical Sciences Centre, City University of Hong Kong, Hong Kong SAR, China
| | - Wenkai Yi
- Department of Biomedical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences; The Tung Biomedical Sciences Centre, City University of Hong Kong, Hong Kong SAR, China
| | - Erfei Chen
- Ministry of Education Key Laboratory of Resource Biology and Biotechnology in Western China; Shaanxi Provincial Key Laboratory of Biotechnology; School of Medicine, Northwest University, Xi’an, China
| | - Rodrigo Villaseñor
- Division of Molecular Biology, Biomedical Center (BMC), Faculty of Medicine, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Tuncay Baubec
- Institute of Biodynamics and Biocomplexity, Department of Biology, Science Faculty, Utrecht University, Utrecht, the Netherlands
| | - Jian Yan
- Ministry of Education Key Laboratory of Resource Biology and Biotechnology in Western China; Shaanxi Provincial Key Laboratory of Biotechnology; School of Medicine, Northwest University, Xi’an, China
- Department of Biomedical Sciences, Jockey Club College of Veterinary Medicine and Life Sciences; The Tung Biomedical Sciences Centre, City University of Hong Kong, Hong Kong SAR, China
- Department of Precision Diagnostic and Therapeutic Technology, The City University of Hong Kong Shenzhen Futian Research Institute, Shenzhen, China
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3
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Coan M, Haefliger S, Ounzain S, Johnson R. Targeting and engineering long non-coding RNAs for cancer therapy. Nat Rev Genet 2024; 25:578-595. [PMID: 38424237 DOI: 10.1038/s41576-024-00693-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/17/2024] [Indexed: 03/02/2024]
Abstract
RNA therapeutics (RNATx) aim to treat diseases, including cancer, by targeting or employing RNA molecules for therapeutic purposes. Amongst the most promising targets are long non-coding RNAs (lncRNAs), which regulate oncogenic molecular networks in a cell type-restricted manner. lncRNAs are distinct from protein-coding genes in important ways that increase their therapeutic potential yet also present hurdles to conventional clinical development. Advances in genome editing, oligonucleotide chemistry, multi-omics and RNA engineering are paving the way for efficient and cost-effective lncRNA-focused drug discovery pipelines. In this Review, we present the emerging field of lncRNA therapeutics for oncology, with emphasis on the unique strengths and challenges of lncRNAs within the broader RNATx framework. We outline the necessary steps for lncRNA therapeutics to deliver effective, durable, tolerable and personalized treatments for cancer.
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Affiliation(s)
- Michela Coan
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
- Conway Institute of Biomedical and Biomolecular Research, University College Dublin, Dublin, Ireland
- School of Medicine, University College Dublin, Dublin, Ireland
| | - Simon Haefliger
- Department of Medical Oncology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Department for BioMedical Research, University of Bern, Bern, Switzerland
| | | | - Rory Johnson
- School of Biology and Environmental Science, University College Dublin, Dublin, Ireland.
- Conway Institute of Biomedical and Biomolecular Research, University College Dublin, Dublin, Ireland.
- Department of Medical Oncology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
- Department for BioMedical Research, University of Bern, Bern, Switzerland.
- FutureNeuro, SFI Research Centre for Chronic and Rare Neurological Diseases, Dublin, Ireland.
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4
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Lee YW, Weissbein U, Blum R, Lee JT. G-quadruplex folding in Xist RNA antagonizes PRC2 activity for stepwise regulation of X chromosome inactivation. Mol Cell 2024; 84:1870-1885.e9. [PMID: 38759625 DOI: 10.1016/j.molcel.2024.04.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 11/25/2023] [Accepted: 04/19/2024] [Indexed: 05/19/2024]
Abstract
How Polycomb repressive complex 2 (PRC2) is regulated by RNA remains an unsolved problem. Although PRC2 binds G-tracts with the potential to form RNA G-quadruplexes (rG4s), whether rG4s fold extensively in vivo and whether PRC2 binds folded or unfolded rG4 are unknown. Using the X-inactivation model in mouse embryonic stem cells, here we identify multiple folded rG4s in Xist RNA and demonstrate that PRC2 preferentially binds folded rG4s. High-affinity rG4 binding inhibits PRC2's histone methyltransferase activity, and stabilizing rG4 in vivo antagonizes H3 at lysine 27 (H3K27me3) enrichment on the inactive X chromosome. Surprisingly, mutagenizing the rG4 does not affect PRC2 recruitment but promotes its release and catalytic activation on chromatin. H3K27me3 marks are misplaced, however, and gene silencing is compromised. Xist-PRC2 complexes become entrapped in the S1 chromosome compartment, precluding the required translocation into the S2 compartment. Thus, Xist rG4 folding controls PRC2 activity, H3K27me3 enrichment, and the stepwise regulation of chromosome-wide gene silencing.
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Affiliation(s)
- Yong Woo Lee
- Department of Molecular Biology, Massachusetts General Hospital and Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
| | - Uri Weissbein
- Department of Molecular Biology, Massachusetts General Hospital and Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
| | - Roy Blum
- Department of Molecular Biology, Massachusetts General Hospital and Department of Genetics, Harvard Medical School, Boston, MA 02114, USA
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital and Department of Genetics, Harvard Medical School, Boston, MA 02114, USA.
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5
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Gu D, Cao T, Yi S, Li X, Liu Y. Transcription suppression of GABARAP mediated by lncRNA XIST-EZH2 interaction triggers caspase-11-dependent inflammatory injury in ulcerative colitis. Immunobiology 2024; 229:152796. [PMID: 38484431 DOI: 10.1016/j.imbio.2024.152796] [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: 10/25/2023] [Revised: 03/01/2024] [Accepted: 03/05/2024] [Indexed: 06/05/2024]
Abstract
BACKGROUND We have previously found that enhancer of zeste homolog 2 (EZH2) is correlated with inflammatory infiltration and mucosal cell injury in ulcerative colitis (UC). This study aims to analyze the role of X-inactive specific transcript (XIST), a possible interactive long non-coding RNA of EZH2, in UC and to explore the mechanisms. METHODS C57BL/6N mice were treated with dextran sulfate sodium (DSS), and mouse colonic mucosal epithelial cells were treated with DSS and lipopolysaccharide (LPS) for UC modeling. The UC-related symptoms in mice, and the viability and apoptosis of mucosal epithelial cells were determined. Inflammatory injury in animal and cellular models were assessed through the levels of ACS, occludin, IL-1β, IL-18, TNF-α, caspase-1, and caspase-11. Molecular interactions between XIST, EZH2, and GABA type A receptor-associated protein (GABARAP) were verified by immunoprecipitation assays, and their functions in inflammatory injury were determined by gain- or loss-of-function assays. RESULTS XIST was highly expressed in DSS-treated mice and in DSS + LPS-treated mucosal epithelial cells. It recruited EZH2, which mediated gene silencing of GABARAP through H3K27me3 modification. Silencing of XIST alleviated body weight loss, colon shortening, and disease active index of mice and reduced inflammatory injuries in their colon tissues. Meanwhile, it reduced apoptosis and inflammation in mucosal epithelial cells. However, these alleviating effects were blocked by either EZH2 overexpression or GABARAP knockdown. Rescue experiments identified caspase-11 as a key effector mediating the inflammatory injury following GABARAP loss. CONCLUSION This study suggests that the XIST-EZH2 interaction-mediated GABARAP inhibition activates caspase-11-dependent inflammatory injury in UC.
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Affiliation(s)
- Dan Gu
- Department of Gastroenterology, The Affiliated Nanhua Hospital, Hengyang Medical School, University of South China, Hengyang 421001, Hunan, PR China
| | - Ting Cao
- Department of Gastroenterology, The Affiliated Nanhua Hospital, Hengyang Medical School, University of South China, Hengyang 421001, Hunan, PR China
| | - Shijie Yi
- Department of Gastrointestinal Surgery, The Affiliated Nanhua Hospital, Hengyang Medical School, University of South China, Hengyang 421001, Hunan, PR China
| | - Xiaoqian Li
- Department of Gastroenterology, The Affiliated Nanhua Hospital, Hengyang Medical School, University of South China, Hengyang 421001, Hunan, PR China
| | - Ya Liu
- Department of Anorectal Surgery, The Affiliated Nanhua Hospital, Hengyang Medical School, University of South China, Hengyang 421001, Hunan, PR China.
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6
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Zacco E, Broglia L, Kurihara M, Monti M, Gustincich S, Pastore A, Plath K, Nagakawa S, Cerase A, Sanchez de Groot N, Tartaglia GG. RNA: The Unsuspected Conductor in the Orchestra of Macromolecular Crowding. Chem Rev 2024; 124:4734-4777. [PMID: 38579177 PMCID: PMC11046439 DOI: 10.1021/acs.chemrev.3c00575] [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: 08/14/2023] [Revised: 01/12/2024] [Accepted: 01/18/2024] [Indexed: 04/07/2024]
Abstract
This comprehensive Review delves into the chemical principles governing RNA-mediated crowding events, commonly referred to as granules or biological condensates. We explore the pivotal role played by RNA sequence, structure, and chemical modifications in these processes, uncovering their correlation with crowding phenomena under physiological conditions. Additionally, we investigate instances where crowding deviates from its intended function, leading to pathological consequences. By deepening our understanding of the delicate balance that governs molecular crowding driven by RNA and its implications for cellular homeostasis, we aim to shed light on this intriguing area of research. Our exploration extends to the methodologies employed to decipher the composition and structural intricacies of RNA granules, offering a comprehensive overview of the techniques used to characterize them, including relevant computational approaches. Through two detailed examples highlighting the significance of noncoding RNAs, NEAT1 and XIST, in the formation of phase-separated assemblies and their influence on the cellular landscape, we emphasize their crucial role in cellular organization and function. By elucidating the chemical underpinnings of RNA-mediated molecular crowding, investigating the role of modifications, structures, and composition of RNA granules, and exploring both physiological and aberrant phase separation phenomena, this Review provides a multifaceted understanding of the intriguing world of RNA-mediated biological condensates.
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Affiliation(s)
- Elsa Zacco
- RNA
Systems Biology Lab, Center for Human Technologies, Istituto Italiano di Tecnologia, Via Enrico Melen, 83, 16152 Genova, Italy
| | - Laura Broglia
- RNA
Systems Biology Lab, Center for Human Technologies, Istituto Italiano di Tecnologia, Via Enrico Melen, 83, 16152 Genova, Italy
| | - Misuzu Kurihara
- RNA
Biology Laboratory, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Michele Monti
- RNA
Systems Biology Lab, Center for Human Technologies, Istituto Italiano di Tecnologia, Via Enrico Melen, 83, 16152 Genova, Italy
| | - Stefano Gustincich
- Central
RNA Lab, Center for Human Technologies, Istituto Italiano di Tecnologia, Via Enrico Melen, 83, 16152 Genova, Italy
| | - Annalisa Pastore
- UK
Dementia Research Institute at the Maurice Wohl Institute of King’s
College London, London SE5 9RT, U.K.
| | - Kathrin Plath
- Department
of Biological Chemistry, David Geffen School
of Medicine at the University of California Los Angeles, Los Angeles, California 90095, United States
| | - Shinichi Nagakawa
- RNA
Biology Laboratory, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
| | - Andrea Cerase
- Blizard
Institute,
Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 4NS, U.K.
- Unit
of Cell and developmental Biology, Department of Biology, Università di Pisa, 56123 Pisa, Italy
| | - Natalia Sanchez de Groot
- Unitat
de Bioquímica, Departament de Bioquímica i Biologia
Molecular, Universitat Autònoma de
Barcelona, 08193 Barcelona, Spain
| | - Gian Gaetano Tartaglia
- RNA
Systems Biology Lab, Center for Human Technologies, Istituto Italiano di Tecnologia, Via Enrico Melen, 83, 16152 Genova, Italy
- Catalan
Institution for Research and Advanced Studies, ICREA, Passeig Lluís Companys 23, 08010 Barcelona, Spain
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7
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Peeters SB, Posynick BJ, Brown CJ. Out of the Silence: Insights into How Genes Escape X-Chromosome Inactivation. EPIGENOMES 2023; 7:29. [PMID: 38131901 PMCID: PMC10742877 DOI: 10.3390/epigenomes7040029] [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: 09/29/2023] [Revised: 11/08/2023] [Accepted: 11/14/2023] [Indexed: 12/23/2023] Open
Abstract
The silencing of all but one X chromosome in mammalian cells is a remarkable epigenetic process leading to near dosage equivalence in X-linked gene products between the sexes. However, equally remarkable is the ability of a subset of genes to continue to be expressed from the otherwise inactive X chromosome-in some cases constitutively, while other genes are variable between individuals, tissues or cells. In this review we discuss the advantages and disadvantages of the approaches that have been used to identify escapees. The identity of escapees provides important clues to mechanisms underlying escape from XCI, an arena of study now moving from correlation to functional studies. As most escapees show greater expression in females, the not-so-inactive X chromosome is a substantial contributor to sex differences in humans, and we highlight some examples of such impact.
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Affiliation(s)
| | | | - Carolyn J. Brown
- Molecular Epigenetics Group, Department of Medical Genetics, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
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8
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Martinez-Castillo M, M. Elsayed A, López-Berestein G, Amero P, Rodríguez-Aguayo C. An Overview of the Immune Modulatory Properties of Long Non-Coding RNAs and Their Potential Use as Therapeutic Targets in Cancer. Noncoding RNA 2023; 9:70. [PMID: 37987366 PMCID: PMC10660772 DOI: 10.3390/ncrna9060070] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 10/25/2023] [Accepted: 11/08/2023] [Indexed: 11/22/2023] Open
Abstract
Long non-coding RNAs (lncRNAs) play pivotal roles in regulating immune responses, immune cell differentiation, activation, and inflammatory processes. In cancer, they are gaining prominence as potential therapeutic targets due to their ability to regulate immune checkpoint molecules and immune-related factors, suggesting avenues for bolstering anti-tumor immune responses. Here, we explore the mechanistic insights into lncRNA-mediated immune modulation, highlighting their impact on immunity. Additionally, we discuss their potential to enhance cancer immunotherapy, augmenting the effectiveness of immune checkpoint inhibitors and adoptive T cell therapies. LncRNAs as therapeutic targets hold the promise of revolutionizing cancer treatments, inspiring further research in this field with substantial clinical implications.
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Affiliation(s)
- Moises Martinez-Castillo
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA; (M.M.-C.); (G.L.-B.); (P.A.)
- Liver, Pancreas and Motility Laboratory, Unit of Research in Experimental Medicine, School of Medicine, Universidad Nacional Autónoma de México (UNAM), Mexico City 06726, Mexico
| | - Abdelrahman M. Elsayed
- Department of Pharmacology & Toxicology, Faculty of Pharmacy, Al-Azhar University, Cairo 11754, Egypt;
- Havener Eye Institute, Department of Ophthalmology and Visual Science, The Ohio State University Wexner Medical Center, Columbus, OH 43210, USA
| | - Gabriel López-Berestein
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA; (M.M.-C.); (G.L.-B.); (P.A.)
- Center for RNA Interference and Non-Coding RNA, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA
| | - Paola Amero
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA; (M.M.-C.); (G.L.-B.); (P.A.)
| | - Cristian Rodríguez-Aguayo
- Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA; (M.M.-C.); (G.L.-B.); (P.A.)
- Center for RNA Interference and Non-Coding RNA, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Houston, TX 77030, USA
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9
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Nepita I, Piazza S, Ruglioni M, Cristiani S, Bosurgi E, Salvadori T, Vicidomini G, Diaspro A, Castello M, Cerase A, Bianchini P, Storti B, Bizzarri R. On the Advent of Super-Resolution Microscopy in the Realm of Polycomb Proteins. BIOLOGY 2023; 12:374. [PMID: 36979066 PMCID: PMC10044799 DOI: 10.3390/biology12030374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/23/2023] [Accepted: 02/24/2023] [Indexed: 03/02/2023]
Abstract
The genomes of metazoans are organized at multiple spatial scales, ranging from the double helix of DNA to whole chromosomes. The intermediate genomic scale of kilobases to megabases, which corresponds to the 50-300 nm spatial scale, is particularly interesting, as the 3D arrangement of chromatin is implicated in multiple regulatory mechanisms. In this context, polycomb group (PcG) proteins stand as major epigenetic modulators of chromatin function, acting prevalently as repressors of gene transcription by combining chemical modifications of target histones with physical crosslinking of distal genomic regions and phase separation. The recent development of super-resolution microscopy (SRM) has strongly contributed to improving our comprehension of several aspects of nano-/mesoscale (10-200 nm) chromatin domains. Here, we review the current state-of-the-art SRM applied to PcG proteins, showing that the application of SRM to PcG activity and organization is still quite limited and mainly focused on the 3D assembly of PcG-controlled genomic loci. In this context, SRM approaches have mostly been applied to multilabel fluorescence in situ hybridization (FISH). However, SRM data have complemented the maps obtained from chromosome capture experiments and have opened a new window to observe how 3D chromatin topology is modulated by PcGs.
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Affiliation(s)
- Irene Nepita
- Nanoscopy, Istituto Italiano di Tecnologia, Via E. Melen 83, 16152 Genova, Italy
| | - Simonluca Piazza
- Molecular Microscopy and Spectroscopy, Istituto Italiano di Tecnologia, Via E. Melen 83, 16152 Genova, Italy
- R&D Department, Genoa Instruments s.r.l., Via E. Melen 83, 16152 Genova, Italy
| | - Martina Ruglioni
- Department of Surgical, Medical and Molecular Pathology, and Critical Care Medicine, University of Pisa, Via Roma 65, 56126 Pisa, Italy
| | - Sofia Cristiani
- Department of Surgical, Medical and Molecular Pathology, and Critical Care Medicine, University of Pisa, Via Roma 65, 56126 Pisa, Italy
| | - Emanuele Bosurgi
- Department of Surgical, Medical and Molecular Pathology, and Critical Care Medicine, University of Pisa, Via Roma 65, 56126 Pisa, Italy
| | - Tiziano Salvadori
- Department of Surgical, Medical and Molecular Pathology, and Critical Care Medicine, University of Pisa, Via Roma 65, 56126 Pisa, Italy
| | - Giuseppe Vicidomini
- Molecular Microscopy and Spectroscopy, Istituto Italiano di Tecnologia, Via E. Melen 83, 16152 Genova, Italy
| | - Alberto Diaspro
- Nanoscopy, Istituto Italiano di Tecnologia, Via E. Melen 83, 16152 Genova, Italy
- DIFILAB, Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova, Italy
| | - Marco Castello
- Nanoscopy, Istituto Italiano di Tecnologia, Via E. Melen 83, 16152 Genova, Italy
- R&D Department, Genoa Instruments s.r.l., Via E. Melen 83, 16152 Genova, Italy
| | - Andrea Cerase
- Unit of Cell and Developmental Biology, Department of Biology, University of Pisa, Strada Statale dell’Abetone Brennero 4, 56123 Pisa, Italy
| | - Paolo Bianchini
- Nanoscopy, Istituto Italiano di Tecnologia, Via E. Melen 83, 16152 Genova, Italy
- DIFILAB, Dipartimento di Fisica, Università degli Studi di Genova, Via Dodecaneso 33, 16146 Genova, Italy
| | - Barbara Storti
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127 Pisa, Italy
| | - Ranieri Bizzarri
- Nanoscopy, Istituto Italiano di Tecnologia, Via E. Melen 83, 16152 Genova, Italy
- Department of Surgical, Medical and Molecular Pathology, and Critical Care Medicine, University of Pisa, Via Roma 65, 56126 Pisa, Italy
- NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza San Silvestro 12, 56127 Pisa, Italy
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10
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Henry S, Kokity L, Pirity MK. Polycomb protein RYBP activates transcription factor Plagl1 during in vitro cardiac differentiation of mouse embryonic stem cells. Open Biol 2023; 13:220305. [PMID: 36751888 PMCID: PMC9905990 DOI: 10.1098/rsob.220305] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023] Open
Abstract
RING1 and YY1 binding protein (RYBP) is primarily known to function as a repressor being a core component of the non-canonical polycomb repressive complexes 1 (ncPRC1s). However, several ncPRC1-independent functions of RYBP have also been described. We previously reported that RYBP is essential for mouse embryonic development and that Rybp null mutant embryonic stem cells cannot form contractile cardiomyocytes (CMCs) in vitro. We also showed that PLAGL1, a cardiac transcription factor, which is often mutated in congenital heart diseases (CHDs), is not expressed in Rybp-null mutant CMCs. However, the underlying mechanism of how RYBP regulates Plagl1 expression was not revealed. Here, we demonstrate that RYBP cooperated with NKX2-5 to transcriptionally activate the P1 and P3 promoters of the Plagl1 gene and that this activation is ncPRC1-independent. We also show that two non-coding RNAs residing in the Plagl1 locus can also regulate the Plagl1 promoters. Finally, PLAGL1 was able to activate Tnnt2, a gene important for contractility of CMCs in transfected HEK293 cells. Our study shows that the activation of Plagl1 by RYBP is important for sarcomere development and contractility, and suggests that RYBP, via its regulatory functions, may contribute to the development of CHDs.
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Affiliation(s)
- Surya Henry
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, 6726 Szeged, Hungary,Doctoral School in Biology, Faculty of Science and Informatics, University of Szeged, 6726 Szeged, Hungary
| | - Lilla Kokity
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, 6726 Szeged, Hungary,Doctoral School in Biology, Faculty of Science and Informatics, University of Szeged, 6726 Szeged, Hungary
| | - Melinda Katalin Pirity
- Institute of Genetics, Biological Research Centre, Eötvös Loránd Research Network, 6726 Szeged, Hungary
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11
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Hyun Y, Kim D. Recent development of computational cluster analysis methods for single-molecule localization microscopy images. Comput Struct Biotechnol J 2023; 21:879-888. [PMID: 36698968 PMCID: PMC9860261 DOI: 10.1016/j.csbj.2023.01.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Revised: 01/07/2023] [Accepted: 01/07/2023] [Indexed: 01/11/2023] Open
Abstract
With the development of super-resolution imaging techniques, it is crucial to understand protein structure at the nanoscale in terms of clustering and organization in a cell. However, cluster analysis from single-molecule localization microscopy (SMLM) images remains challenging because the classical computational cluster analysis methods developed for conventional microscopy images do not apply to pointillism SMLM data, necessitating the development of distinct methods for cluster analysis from SMLM images. In this review, we discuss the development of computational cluster analysis methods for SMLM images by categorizing them into classical and machine-learning-based methods. Finally, we address possible future directions for machine learning-based cluster analysis methods for SMLM data.
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Affiliation(s)
- Yoonsuk Hyun
- Department of Mathematics, Inha University, Republic of Korea
| | - Doory Kim
- Department of Chemistry, Hanyang University, Republic of Korea
- Research Institute for Convergence of Basic Science, Hanyang University, Republic of Korea
- Institute of Nano Science and Technology, Hanyang University, Republic of Korea
- Research Institute for Natural Sciences, Hanyang University, Republic of Korea
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12
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Functional Relationships between Long Non-Coding RNAs and Estrogen Receptor Alpha: A New Frontier in Hormone-Responsive Breast Cancer Management. Int J Mol Sci 2023; 24:ijms24021145. [PMID: 36674656 PMCID: PMC9863308 DOI: 10.3390/ijms24021145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 01/03/2023] [Accepted: 01/05/2023] [Indexed: 01/11/2023] Open
Abstract
In the complex and articulated machinery of the human genome, less than 2% of the transcriptome encodes for proteins, while at least 75% is actively transcribed into non-coding RNAs (ncRNAs). Among the non-coding transcripts, those ≥200 nucleotides long (lncRNAs) are receiving growing attention for their involvement in human diseases, particularly cancer. Genomic studies have revealed the multiplicity of processes, including neoplastic transformation and tumor progression, in which lncRNAs are involved by regulating gene expression at epigenetic, transcriptional, and post-transcriptional levels by mechanism(s) that still need to be clarified. In breast cancer, several lncRNAs were identified and demonstrated to have either oncogenic or tumor-suppressive roles. The functional understanding of the mechanisms of lncRNA action in this disease could represent a potential for translational applications, as these molecules may serve as novel biomarkers of clinical use and potential therapeutic targets. This review highlights the relationship between lncRNAs and the principal hallmark of the luminal breast cancer phenotype, estrogen receptor α (ERα), providing an overview of new potential ways to inhibit estrogenic signaling via this nuclear receptor toward escaping resistance to endocrine therapy.
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13
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Grimm NB, Lee JT. Selective Xi reactivation and alternative methods to restore MECP2 function in Rett syndrome. Trends Genet 2022; 38:920-943. [PMID: 35248405 PMCID: PMC9915138 DOI: 10.1016/j.tig.2022.01.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 01/15/2022] [Accepted: 01/19/2022] [Indexed: 10/19/2022]
Abstract
The human X-chromosome harbors only 4% of our genome but carries over 20% of genes associated with intellectual disability. Given that they inherit only one X-chromosome, males are more frequently affected by X-linked neurodevelopmental genetic disorders than females. However, despite inheriting two X-chromosomes, females can also be affected because X-chromosome inactivation enables only one of two X-chromosomes to be expressed per cell. For Rett syndrome and similar X-linked disorders affecting females, disease-specific treatments have remained elusive. However, a cure may be found within their own cells because every sick cell carries a healthy copy of the affected gene on the inactive X (Xi). Therefore, selective Xi reactivation may be a viable approach that would address the root cause of various X-linked disorders. Here, we discuss Rett syndrome and compare current approaches in the pharmaceutical pipeline to restore MECP2 function. We then focus on Xi reactivation and review available methods, lessons learned, and future directions.
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Affiliation(s)
- Niklas-Benedikt Grimm
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA; Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA; Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain; Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA, USA; Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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14
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Emerging roles and potential clinical applications of long non-coding RNAs in hepatocellular carcinoma. Biomed Pharmacother 2022; 153:113327. [PMID: 35779423 DOI: 10.1016/j.biopha.2022.113327] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 06/20/2022] [Accepted: 06/22/2022] [Indexed: 12/23/2022] Open
Abstract
Hepatocellular carcinoma is one of the most common highly malignant tumors in humans, as well as the leading cause of cancer-related death worldwide. Growing evidence has indicated that lncRNAs are implicated in different molecular mechanisms, including interactions with DNA, RNA, or protein, so that to regulate the gene expression at epigenetic, transcriptional, or posttranscriptional level. Moreover, the mechanism of action of lncRNA is closely related to its subcellular localization. An increasing number of studies have certified that lncRNA plays a significant biological function in the occurrence and development of hepatocellular carcinoma, such as involving in cell proliferation, metastasis, apoptosis, ferroptosis, autophagy, and reprogramming of energy metabolism. As a result, lncRNA has great potential as a novel biomarker for diagnosis or therapeutics of hepatocellular carcinoma. In this review, we highlight the correlation between subcellular localization of lncRNA and its mechanism of action, discuss the biological roles of lncRNA and the latest research advances in hepatocellular carcinoma, and emphasize the potential of lncRNA as a therapeutic target for advanced patients of hepatocellular carcinoma.
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15
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Substoichiometric action of long noncoding RNAs. Nat Cell Biol 2022; 24:608-615. [PMID: 35562482 DOI: 10.1038/s41556-022-00911-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 04/01/2022] [Indexed: 11/08/2022]
Abstract
Low expression levels and stoichiometric imbalances of long noncoding RNAs (lncRNAs) are often used as evidence for their probable lack of function or for limiting the scope of their potential influence. Recent advances in our understanding of the substoichiometric functions of lncRNAs challenge these notions and suggest routes through which unabundant lncRNAs can affect cellular functions and gene regulatory networks.
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16
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Cao PW, Liu L, Li ZH, Cao F, Liu FB. Prognostic Value of Drug Targets Predicted Using Deep Bioinformatic Analysis of m6A-Associated lncRNA-Based Pancreatic Cancer Model Characteristics and Its Tumour Microenvironment. Front Genet 2022; 13:853471. [PMID: 35547245 PMCID: PMC9081602 DOI: 10.3389/fgene.2022.853471] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 03/31/2022] [Indexed: 12/14/2022] Open
Abstract
The role of N6-methyladenosine (m6A)-associated long-stranded non-coding RNA (lncRNA) in pancreatic cancer is unclear. Therefore, we analysed the characteristics and tumour microenvironment in pancreatic cancer and determined the value of m6A-related lncRNAs for prognosis and drug target prediction. An m6A-lncRNA co-expression network was constructed using The Cancer Genome Atlas database to screen m6A-related lncRNAs. Prognosis-related lncRNAs were screened using univariate Cox regression; patients were divided into high- and low-risk groups and randomised into training and test groups. In the training group, least absolute shrinkage and selection operator (LASSO) was used for regression analysis and to construct a prognostic model, which was validated in the test group. Tumor mutational burden (TMB), immune evasion, and immune function of risk genes were analysed using R; drug sensitivity and potential drugs were examined using the Genomics of Drug Sensitivity in Cancer database. We screened 129 m6A-related lncRNAs; 17 prognosis-related m6A-related lncRNAs were obtained using multivariate analysis and three m6A-related lncRNAs (AC092171.5, MEG9, and AC002091.1) were screened using LASSO regression. Survival rates were significantly higher (p < 0.05) in the low-risk than in the high-risk group. Risk score was an independent predictor affecting survival (p < 0.001), with the highest risk score being obtained by calculating the c-index. The TMB significantly differed between the high- and low-risk groups (p < 0.05). In the high- and low-risk groups, mutations were detected in 61 of 70 samples and 49 of 71 samples, respectively, with KRAS, TP53, and SMAD4 showing the highest mutation frequencies in both groups. A lower survival rate was observed in patients with a high versus low TMB. Immune function HLA, Cytolytic activity, and Inflammation-promoting, T cell co-inhibition, Check-point, and T cell co-stimulation significantly differed in different subgroups (p < 0.05). Immune evasion scores were significantly higher in the high-risk group than in the low-risk group. Eight sensitive drugs were screened: ABT.888, ATRA, AP.24534, AG.014699, ABT.263, axitinib, A.443654, and A.770041. We screened m6A-related lncRNAs using bioinformatics, constructed a prognosis-related model, explored TMB and immune function differences in pancreatic cancer, and identified potential therapeutic agents, providing a foundation for further studies of pancreatic cancer diagnosis and treatment.
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Affiliation(s)
- Peng-Wei Cao
- Hepatopancreatobiliary Surgery, Department of General Surgery, The First Afliated Hospital of Anhui Medical University, Hefei, China.,NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, China
| | - Lei Liu
- Hepatopancreatobiliary Surgery, Department of General Surgery, The First Afliated Hospital of Anhui Medical University, Hefei, China
| | - Zi-Han Li
- Hepatopancreatobiliary Surgery, Department of General Surgery, The First Afliated Hospital of Anhui Medical University, Hefei, China
| | - Feng Cao
- Department of General Surgery, The Second Hospital of Anhui Medical University, Hefei, China
| | - Fu-Bao Liu
- Hepatopancreatobiliary Surgery, Department of General Surgery, The First Afliated Hospital of Anhui Medical University, Hefei, China
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17
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Kalem MC, Panepinto JC. Long Non-Coding RNAs in Cryptococcus neoformans: Insights Into Fungal Pathogenesis. Front Cell Infect Microbiol 2022; 12:858317. [PMID: 35372111 PMCID: PMC8968117 DOI: 10.3389/fcimb.2022.858317] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Accepted: 02/18/2022] [Indexed: 12/18/2022] Open
Abstract
Long non-coding RNAs (lncRNAs) are highly expressed and can modulate multiple cellular processes including transcription, splicing, translation, and many diverse signaling events. LncRNAs can act as sponges for miRNAs, RNA and DNA binding proteins, functioning as competitive endogenous RNAs. The contribution of lncRNAs to microbial pathogenesis is largely neglected in eukaryotic pathogens despite the abundance of RNA sequencing datasets encompassing conditions of stress, gene deletions and conditions that mimic the host environment. The human fungal pathogen Cryptococcus neoformans encodes 6975 (84%) protein-coding and 1359 (16%) non-protein-coding RNAs, of which 1182 (14.2%) are lncRNAs defined by a threshold of greater than 200 nucleotides in length. Here, we discuss the current state of knowledge in C. neoformans lncRNA biology. Utilizing existing RNA seq datasets, we examine trends in lncRNA expression and discuss potential implications for pathogenesis.
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Affiliation(s)
- Murat C. Kalem
- Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, Jacobs School of Medicine and Biomedical Sciences, State University of New York (SUNY), University at Buffalo, Buffalo, NY, United States
| | - John C. Panepinto
- Department of Microbiology and Immunology, Witebsky Center for Microbial Pathogenesis and Immunology, Jacobs School of Medicine and Biomedical Sciences, State University of New York (SUNY), University at Buffalo, Buffalo, NY, United States
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18
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Cerase A, Calabrese JM, Tartaglia GG. Phase separation drives X-chromosome inactivation. Nat Struct Mol Biol 2022; 29:183-185. [PMID: 35301494 DOI: 10.1038/s41594-021-00697-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Andrea Cerase
- Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK. .,Department of Biology, Università di Pisa, Pisa, Italy.
| | - J Mauro Calabrese
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Gian Gaetano Tartaglia
- Department of Biology 'Charles Darwin', Sapienza University of Rome, Rome, Italy. .,Department of Neuroscience and Brain Technologies, Istituto Italiano di Tecnologia, Genoa, Italy.
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19
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Xist spatially amplifies SHARP/SPEN recruitment to balance chromosome-wide silencing and specificity to the X chromosome. Nat Struct Mol Biol 2022; 29:239-249. [PMID: 35301492 DOI: 10.1038/s41594-022-00739-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 01/28/2022] [Indexed: 11/08/2022]
Abstract
Although thousands of long non-coding RNAs (lncRNAs) are encoded in mammalian genomes, their mechanisms of action are poorly understood, in part because they are often expressed at lower levels than their proposed targets. One such lncRNA is Xist, which mediates chromosome-wide gene silencing on one of the two X chromosomes (X) to achieve gene expression balance between males and females. How a limited number of Xist molecules can mediate robust silencing of a much larger number of target genes while maintaining specificity exclusively to genes on the X within each cell is not well understood. Here, we show that Xist drives non-stoichiometric recruitment of the essential silencing protein SHARP (also known as SPEN) to amplify its abundance across the inactive X, including at regions not directly occupied by Xist. This amplification is achieved through concentration-dependent homotypic assemblies of SHARP on the X and is required for chromosome-wide silencing. Expression of Xist at higher levels leads to increased localization at autosomal regions, demonstrating that low levels of Xist are critical for ensuring its specificity to the X. We show that Xist (through SHARP) acts to suppress production of its own RNA which may act to constrain overall RNA levels and restrict its ability to spread beyond the X. Together, our results demonstrate a spatial amplification mechanism that allows Xist to achieve two essential but countervailing regulatory objectives: chromosome-wide gene silencing and specificity to the X. This suggests a more general mechanism by which other low-abundance lncRNAs could balance specificity to, and robust control of, their regulatory targets.
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20
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Markaki Y, Gan Chong J, Wang Y, Jacobson EC, Luong C, Tan SYX, Jachowicz JW, Strehle M, Maestrini D, Banerjee AK, Mistry BA, Dror I, Dossin F, Schöneberg J, Heard E, Guttman M, Chou T, Plath K. Xist nucleates local protein gradients to propagate silencing across the X chromosome. Cell 2021; 184:6174-6192.e32. [PMID: 34813726 PMCID: PMC8671326 DOI: 10.1016/j.cell.2021.10.022] [Citation(s) in RCA: 56] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 07/29/2021] [Accepted: 10/11/2021] [Indexed: 02/08/2023]
Abstract
The lncRNA Xist forms ∼50 diffraction-limited foci to transcriptionally silence one X chromosome. How this small number of RNA foci and interacting proteins regulate a much larger number of X-linked genes is unknown. We show that Xist foci are locally confined, contain ∼2 RNA molecules, and nucleate supramolecular complexes (SMACs) that include many copies of the critical silencing protein SPEN. Aggregation and exchange of SMAC proteins generate local protein gradients that regulate broad, proximal chromatin regions. Partitioning of numerous SPEN molecules into SMACs is mediated by their intrinsically disordered regions and essential for transcriptional repression. Polycomb deposition via SMACs induces chromatin compaction and the increase in SMACs density around genes, which propagates silencing across the X chromosome. Our findings introduce a mechanism for functional nuclear compartmentalization whereby crowding of transcriptional and architectural regulators enables the silencing of many target genes by few RNA molecules.
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Affiliation(s)
- Yolanda Markaki
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Johnny Gan Chong
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Yuying Wang
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Elsie C Jacobson
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Christy Luong
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Shawn Y X Tan
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Joanna W Jachowicz
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Mackenzie Strehle
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Davide Maestrini
- Department of Computational Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Abhik K Banerjee
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Bhaven A Mistry
- Department of Computational Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA; Claremont McKenna College, Claremont, CA 91711, USA
| | - Iris Dror
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Francois Dossin
- European Molecular Biology Laboratory, Director's Unit, Heidelberg 69117, Germany
| | - Johannes Schöneberg
- Departments of Pharmacology & Chemistry and Biochemistry, University of California San Diego, San Diego, CA 92093, USA
| | - Edith Heard
- European Molecular Biology Laboratory, Director's Unit, Heidelberg 69117, Germany
| | - Mitchell Guttman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Tom Chou
- Department of Computational Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
| | - Kathrin Plath
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA.
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21
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Abstract
Although long noncoding RNAs (lncRNAs) are generally expressed at low levels, emerging evidence has revealed that many play important roles in gene regulation by a variety of mechanisms as they engage with proteins. Given that the abundance of proteins often greatly exceeds that of their interacting lncRNAs, quantification of the relative abundance, or even the exact stoichiometry in some cases, within lncRNA-protein complexes is helpful for understanding of the mechanism(s) of action of lncRNAs. We discuss methods used to examine lncRNA and protein expression at the single cell, subcellular, and suborganelle levels, the average and local lncRNA concentration in cells, as well as how lncRNAs can modulate the functions of their interacting proteins even at a low stoichiometric concentration.
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Affiliation(s)
- Man Wu
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Liang-Zhong Yang
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
| | - Ling-Ling Chen
- State Key Laboratory of Molecular Biology, Shanghai Key Laboratory of Molecular Andrology, CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200031, China
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
- School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
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22
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Trotman JB, Braceros KCA, Cherney RE, Murvin MM, Calabrese JM. The control of polycomb repressive complexes by long noncoding RNAs. WILEY INTERDISCIPLINARY REVIEWS. RNA 2021; 12:e1657. [PMID: 33861025 PMCID: PMC8500928 DOI: 10.1002/wrna.1657] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 01/12/2021] [Accepted: 03/19/2021] [Indexed: 02/06/2023]
Abstract
The polycomb repressive complexes 1 and 2 (PRCs; PRC1 and PRC2) are conserved histone-modifying enzymes that often function cooperatively to repress gene expression. The PRCs are regulated by long noncoding RNAs (lncRNAs) in complex ways. On the one hand, specific lncRNAs cause the PRCs to engage with chromatin and repress gene expression over genomic regions that can span megabases. On the other hand, the PRCs bind RNA with seemingly little sequence specificity, and at least in the case of PRC2, direct RNA-binding has the effect of inhibiting the enzyme. Thus, some RNAs appear to promote PRC activity, while others may inhibit it. The reasons behind this apparent dichotomy are unclear. The most potent PRC-activating lncRNAs associate with chromatin and are predominantly unspliced or harbor unusually long exons. Emerging data imply that these lncRNAs promote PRC activity through internal RNA sequence elements that arise and disappear rapidly in evolutionary time. These sequence elements may function by interacting with common subsets of RNA-binding proteins that recruit or stabilize PRCs on chromatin. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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Affiliation(s)
- Jackson B. Trotman
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Keean C. A. Braceros
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Curriculum in Mechanistic, Interdisciplinary Studies of Biological Systems, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Rachel E. Cherney
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - McKenzie M. Murvin
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - J. Mauro Calabrese
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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23
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Szanto A, Aguilar R, Kesner B, Blum R, Wang D, Cifuentes-Rojas C, Del Rosario BC, Kis-Toth K, Lee JT. A disproportionate impact of G9a methyltransferase deficiency on the X chromosome. Genes Dev 2021; 35:1035-1054. [PMID: 34168040 PMCID: PMC8247598 DOI: 10.1101/gad.337592.120] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 05/27/2021] [Indexed: 01/05/2023]
Abstract
In this study from Szanto et al., the authors investigated the role of G9a, a histone methyltransferase responsible for the dimethylation of histone H3 at lysine 9 (H3K9me2) that plays key roles in transcriptional silencing of developmentally regulated genes, in X-chromosome inactivation (XCI). They found a female-specific function of G9a and demonstrate that deleting G9a has a disproportionate impact on the X chromosome relative to the rest of the genome, and show RNA tethers G9a for allele-specific targeting of the H3K9me2 modification and the G9a–RNA interaction is essential for XCI. G9a is a histone methyltransferase responsible for the dimethylation of histone H3 at lysine 9 (H3K9me2). G9a plays key roles in transcriptional silencing of developmentally regulated genes, but its role in X-chromosome inactivation (XCI) has been under debate. Here, we uncover a female-specific function of G9a and demonstrate that deleting G9a has a disproportionate impact on the X chromosome relative to the rest of the genome. G9a deficiency causes a failure of XCI and female-specific hypersensitivity to drug inhibition of H3K9me2. We show that G9a interacts with Tsix and Xist RNAs, and that competitive inhibition of the G9a-RNA interaction recapitulates the XCI defect. During XCI, Xist recruits G9a to silence X-linked genes on the future inactive X. In parallel on the future Xa, Tsix recruits G9a to silence Xist in cis. Thus, RNA tethers G9a for allele-specific targeting of the H3K9me2 modification and the G9a-RNA interaction is essential for XCI.
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Affiliation(s)
- Attila Szanto
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Rodrigo Aguilar
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Barry Kesner
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Roy Blum
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Danni Wang
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Catherine Cifuentes-Rojas
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Brian C Del Rosario
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Katalin Kis-Toth
- Department of Rheumatology, Beth Israel Deaconess Medical Center, Harvard Medical School Boston, Massachusetts 02115, USA
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.,Department of Genetics, The Blavatnik Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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24
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iDRiP for the systematic discovery of proteins bound directly to noncoding RNA. Nat Protoc 2021; 16:3672-3694. [PMID: 34108731 DOI: 10.1038/s41596-021-00555-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Accepted: 04/13/2021] [Indexed: 11/09/2022]
Abstract
More than 90% of the human genome is transcribed into noncoding RNAs, but their functional characterization has lagged behind. A major bottleneck in the understanding of their functions and mechanisms has been a dearth of systematic methods for identifying interacting protein partners. There now exist several methods, including identification of direct RNA interacting proteins (iDRiP), chromatin isolation by RNA purification (ChIRP), and RNA antisense purification, each previously applied towards identifying a proteome for the prototype noncoding RNA, Xist. iDRiP has recently been modified to successfully identify proteomes for two additional noncoding RNAs of interest, TERRA and U1 RNA. Here we describe the modified protocol in detail, highlighting technical differences that facilitate capture of various noncoding RNAs. The protocol can be applied to short and long RNAs in both cultured cells and tissues, and requires ~1 week from start to finish. Here we also perform a comparative analysis between iDRiP and ChIRP. We obtain partially overlapping profiles, but find that iDRiP yields a greater number of specific proteins and fewer mitochondrial contaminants. With an increasing number of essential long noncoding RNAs being described, robust RNA-centric protein capture methods are critical for the probing of noncoding RNA function and mechanism.
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25
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Trotman JB, Lee DM, Cherney RE, Kim SO, Inoue K, Schertzer MD, Bischoff SR, Cowley DO, Calabrese J. Elements at the 5' end of Xist harbor SPEN-independent transcriptional antiterminator activity. Nucleic Acids Res 2020; 48:10500-10517. [PMID: 32986830 PMCID: PMC7544216 DOI: 10.1093/nar/gkaa789] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 08/20/2020] [Accepted: 09/12/2020] [Indexed: 12/22/2022] Open
Abstract
The Xist lncRNA requires Repeat A, a conserved RNA element located in its 5' end, to induce gene silencing during X-chromosome inactivation. Intriguingly, Repeat A is also required for production of Xist. While silencing by Repeat A requires the protein SPEN, how Repeat A promotes Xist production remains unclear. We report that in mouse embryonic stem cells, expression of a transgene comprising the first two kilobases of Xist (Xist-2kb) causes transcriptional readthrough of downstream polyadenylation sequences. Readthrough required Repeat A and the ∼750 nucleotides downstream, did not require SPEN, and was attenuated by splicing. Despite associating with SPEN and chromatin, Xist-2kb did not robustly silence transcription, whereas a 5.5-kb Xist transgene robustly silenced transcription and read through its polyadenylation sequence. Longer, spliced Xist transgenes also induced robust silencing yet terminated efficiently. Thus, in contexts examined here, Xist requires sequence elements beyond its first two kilobases to robustly silence transcription, and the 5' end of Xist harbors SPEN-independent transcriptional antiterminator activity that can repress proximal cleavage and polyadenylation. In endogenous contexts, this antiterminator activity may help produce full-length Xist RNA while rendering the Xist locus resistant to silencing by the same repressive complexes that the lncRNA recruits to other genes.
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Affiliation(s)
- Jackson B Trotman
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
| | - David M Lee
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, Chapel Hill, NC 27599, USA
| | - Rachel E Cherney
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, Chapel Hill, NC 27599, USA
| | - Susan O Kim
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
| | - Kaoru Inoue
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
| | - Megan D Schertzer
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, Chapel Hill, NC 27599, USA
| | - Steven R Bischoff
- Animal Models Core, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC 27599, USA
| | - Dale O Cowley
- Animal Models Core, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC 27599, USA
| | - J Mauro Calabrese
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, Chapel Hill, NC 27599, USA
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26
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Schertzer MD, Murvin MM, Calabrese JM. Using RNA Sequencing and Spike-in RNAs to Measure Intracellular Abundance of lncRNAs and mRNAs. Bio Protoc 2020; 10:e3772. [PMID: 33204768 DOI: 10.21769/bioprotoc.3772] [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] [Indexed: 01/07/2023] Open
Abstract
Long noncoding RNAs (lncRNAs) play essential roles in normal physiology and in disease but their mechanisms of action can be challenging to identify. For mechanistic studies, it is often useful to know a lncRNA's intracellular abundance, i.e., approximately how many molecules of the lncRNA are present in a typical cell of a cell-type of interest. At least two approaches have been used to approximate lncRNA intracellular abundance: single-molecule sensitivity RNA fluorescence in situ hybridization (smFISH) and single-gene, calibrated reverse-transcription followed by quantitative PCR (RT-qPCR). However, like all experimental approaches, these methods have their limitations. smFISH, when analyzed using diffraction-limited microscopy, can underestimate intracellular abundance, especially for lncRNAs that accumulate in focused subcellular regions. Calibrated RT-qPCR may return inaccurate estimates of abundance because individual PCR amplicons spaced across the length of a transcript can vary in their efficiency of reverse transcription. Here, we describe a sequencing-based approach that is straightforward, orthogonal to smFISH and RT-qPCR, and can be used to approximate the intracellular abundance for most expressed long RNAs (lncRNAs and mRNAs) in a cell type of interest. Firstly, the average weight of total RNA per cell for the cell type of interest is estimated by replicate rounds of RNA purification from a known number of cells. Secondly, an rRNA-depletion RNA-Seq protocol is performed after adding spike-in control RNAs to a known quantity of total cellular RNA. Lastly, by comparing read counts per transcript to a standard curve derived from the spiked-in RNAs, the intracellular abundance for each transcript is estimated. The sequencing-based approach provides a powerful complement to existing methods, particularly in situations where it is desirable to quantify the abundance of multiple lncRNAs and/or mRNAs simultaneously.
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Affiliation(s)
- Megan D Schertzer
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC, 27599, USA.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC, 27599, USA
| | - McKenzie M Murvin
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC, 27599, USA.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC, 27599, USA
| | - J Mauro Calabrese
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, 120 Mason Farm Road, Chapel Hill, NC, 27599, USA
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Abstract
Background Several long noncoding RNAs (lncRNAs) have been shown to function as components of molecular machines that play fundamental roles in biology. While the number of annotated lncRNAs in mammalian genomes has greatly expanded, studying lncRNA function has been a challenge due to their diverse biological roles and because lncRNA loci can contain multiple molecular modes that may exert function. Results We previously generated and characterized a cohort of 20 lncRNA loci knockout mice. Here, we extend this initial study and provide a more detailed analysis of the highly conserved lncRNA locus, taurine-upregulated gene 1 (Tug1). We report that Tug1-knockout male mice are sterile with underlying defects including a low number of sperm and abnormal sperm morphology. Because lncRNA loci can contain multiple modes of action, we wanted to determine which, if any, potential elements contained in the Tug1 genomic region have any activity. Using engineered mouse models and cell-based assays, we provide evidence that the Tug1 locus harbors two distinct noncoding regulatory activities, as a cis-DNA repressor that regulates neighboring genes and as a lncRNA that can regulate genes by a trans-based function. We also show that Tug1 contains an evolutionary conserved open reading frame that when overexpressed produces a stable protein which impacts mitochondrial membrane potential, suggesting a potential third coding function. Conclusions Our results reveal an essential role for the Tug1 locus in male fertility and uncover evidence for distinct molecular modes in the Tug1 locus, thus highlighting the complexity present at lncRNA loci.
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Aeby E, Lee HG, Lee YW, Kriz A, del Rosario BC, Oh HJ, Boukhali M, Haas W, Lee JT. Decapping enzyme 1A breaks X-chromosome symmetry by controlling Tsix elongation and RNA turnover. Nat Cell Biol 2020; 22:1116-1129. [PMID: 32807903 DOI: 10.1038/s41556-020-0558-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Accepted: 07/09/2020] [Indexed: 12/27/2022]
Abstract
How allelic asymmetry is generated remains a major unsolved problem in epigenetics. Here we model the problem using X-chromosome inactivation by developing "BioRBP", an enzymatic RNA-proteomic method that enables probing of low-abundance interactions and an allelic RNA-depletion and -tagging system. We identify messenger RNA-decapping enzyme 1A (DCP1A) as a key regulator of Tsix, a noncoding RNA implicated in allelic choice through X-chromosome pairing. DCP1A controls Tsix half-life and transcription elongation. Depleting DCP1A causes accumulation of X-X pairs and perturbs the transition to monoallelic Tsix expression required for Xist upregulation. While ablating DCP1A causes hyperpairing, forcing Tsix degradation resolves pairing and enables Xist upregulation. We link pairing to allelic partitioning of CCCTC-binding factor (CTCF) and show that tethering DCP1A to one Tsix allele is sufficient to drive monoallelic Xist expression. Thus, DCP1A flips a bistable switch for the mutually exclusive determination of active and inactive Xs.
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29
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Frank L, Rippe K. Repetitive RNAs as Regulators of Chromatin-Associated Subcompartment Formation by Phase Separation. J Mol Biol 2020; 432:4270-4286. [DOI: 10.1016/j.jmb.2020.04.015] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 04/14/2020] [Accepted: 04/14/2020] [Indexed: 12/21/2022]
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Strehle M, Guttman M. Xist drives spatial compartmentalization of DNA and protein to orchestrate initiation and maintenance of X inactivation. Curr Opin Cell Biol 2020; 64:139-147. [PMID: 32535328 DOI: 10.1016/j.ceb.2020.04.009] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 04/13/2020] [Accepted: 04/23/2020] [Indexed: 12/15/2022]
Abstract
X chromosome inactivation (XCI) is the process whereby one of the X chromosomes in female mammalian cells is silenced to equalize X-linked gene expression with males. XCI depends on the long noncoding RNA Xist, which coats the inactive X chromosome in cis and triggers a cascade of events that ultimately lead to chromosome-wide transcriptional silencing that is stable for the lifetime of an organism. In recent years, the discovery of proteins that interact with Xist have led to new insights into how the initiation of XCI occurs. Nevertheless, there are still various unknowns about the mechanisms by which Xist orchestrates and maintains stable X-linked silencing. Here, we review recent work elucidating the role of Xist and its protein partners in mediating chromosome-wide transcriptional repression, as well as discuss a model by which Xist may compartmentalize proteins across the inactive X chromosome to enable both the initiation and maintenance of XCI.
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Affiliation(s)
- Mackenzie Strehle
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Mitchell Guttman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.
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31
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Xu YJ, Liu PP, Ng SC, Teng ZQ, Liu CM. Regulatory networks between Polycomb complexes and non-coding RNAs in the central nervous system. J Mol Cell Biol 2020; 12:327-336. [PMID: 31291646 PMCID: PMC7288736 DOI: 10.1093/jmcb/mjz058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Revised: 02/26/2019] [Accepted: 06/11/2019] [Indexed: 01/29/2023] Open
Abstract
High-throughput sequencing has facilitated the identification of many types of non-coding RNAs (ncRNAs) involved in diverse cellular processes. NcRNAs as epigenetic mediators play key roles in neuronal development, maintenance, and dysfunction by controlling gene expression at multiple levels. NcRNAs may not only target specific DNA or RNA for gene silence but may also directly interact with chromatin-modifying proteins like Polycomb group (PcG) proteins to drive orchestrated transcriptional programs. Recent significant progress has been made in characterizing ncRNAs and PcG proteins involved in transcriptional, post-transcriptional, and epigenetic regulation. More importantly, dysregulation of ncRNAs, PcG proteins, and interplay among them is closely associated with the pathogenesis of central nervous system (CNS) disorders. In this review, we focus on the interplay between ncRNAs and PcG proteins in the CNS and highlight the functional roles of the partnership during neural development and diseases.
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Affiliation(s)
- Ya-Jie Xu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Pei-Pei Liu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
| | - Shyh-Chang Ng
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing 100049, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhao-Qian Teng
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing 100049, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
| | - Chang-Mei Liu
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
- Savaid Medical School, University of Chinese Academy of Sciences, Beijing 100049, China
- Institute for Stem Cell and Regeneration, Chinese Academy of Sciences, Beijing 100101, China
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32
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Dumbović G, Sanjuan X, Perucho M, Forcales SV. Stimulated emission depletion (STED) super resolution imaging of RNA- and protein-containing domains in fixed cells. Methods 2020; 187:68-76. [PMID: 32360441 DOI: 10.1016/j.ymeth.2020.04.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 04/25/2020] [Accepted: 04/26/2020] [Indexed: 12/20/2022] Open
Abstract
Super resolution microscopy has changed our capability to visualize and understand spatial arrangements of RNA- and protein-containing domains in individual cells. In a previous study, we described a novel lncRNA, Tumor-associated NBL2 transcript (TNBL), which originates from a primate specific macrosatellite repeat. We aimed to describe several aspects of TNBL lncRNA, with one focus being pinpointing its precise location in the nucleus, as well as visualizing its interactions with proteins to deduce its functionality. Using a combination of STimulated Emission Depletion (STED) super resolution microscopy, single molecule RNA (smRNA) FISH against TNBL, and immunofluorescence against SAM68 perinucleolar body, we resolved the spatial complexity of the interaction between TNBL aggregates and SAM68 bodies at the perinucleolar region. Here, we describe protocols for a step-by-step optimized smRNA FISH/IF and STED imaging, detailing parameter settings, and three-dimensional data analysis of spatial positioning of subnuclear structures. These protocols can be employed for single-cell imaging of complex nuclear RNA-protein structures.
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Affiliation(s)
- Gabrijela Dumbović
- BioFrontiers Institute, University of Colorado at Boulder, Boulder, CO, USA.
| | - Xavier Sanjuan
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona, Spain; Advanced Light Microscopy Unit, Center for Genomic Regulation, Barcelona, Spain
| | - Manuel Perucho
- Cancer Genetics and Epigenetics, Program of Predictive and Personalized Medicine of Cancer (PMPPC), Health Science Research Institute Germans Trias i Pujol (IGTP), Badalona, Spain; Tumor Initiation and Maintenance Program, Sanford Burnham Prebys (SBP) Medical Discovery Institute, La Jolla, CA, USA
| | - Sonia-V Forcales
- Department of Pathology and Experimental Therapeutics, Faculty of Medicine and Health Sciences, University of Barcelona, L' Hospitalet de Llobregat, Barcelona, Spain.
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33
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Akkipeddi SMK, Velleca AJ, Carone DM. Probing the function of long noncoding RNAs in the nucleus. Chromosome Res 2020; 28:87-110. [PMID: 32026224 PMCID: PMC7131881 DOI: 10.1007/s10577-019-09625-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 12/20/2019] [Accepted: 12/29/2019] [Indexed: 12/26/2022]
Abstract
The nucleus is a highly organized and dynamic environment where regulation and coordination of processes such as gene expression and DNA replication are paramount. In recent years, noncoding RNAs have emerged as key participants in the regulation of nuclear processes. There are a multitude of functional roles for long noncoding RNA (lncRNA), mediated through their ability to act as molecular scaffolds bridging interactions with proteins, chromatin, and other RNA molecules within the nuclear environment. In this review, we discuss the diversity of techniques that have been developed to probe the function of nuclear lncRNAs, along with the ways in which those techniques have revealed insights into their mechanisms of action. Foundational observations into lncRNA function have been gleaned from molecular cytology-based, single-cell approaches to illuminate both the localization and abundance of lncRNAs in addition to their potential binding partners. Biochemical, extraction-based approaches have revealed the molecular contacts between lncRNAs and other molecules within the nuclear environment and how those interactions may contribute to nuclear organization and regulation. Using examples of well-studied nuclear lncRNAs, we demonstrate that the emerging functions of individual lncRNAs have been most clearly deduced from combined cytology and biochemical approaches tailored to study specific lncRNAs. As more functional nuclear lncRNAs continue to emerge, the development of additional technologies to study their interactions and mechanisms of action promise to continually expand our understanding of nuclear organization, chromosome architecture, genome regulation, and disease states.
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Affiliation(s)
| | - Anthony J Velleca
- Department of Molecular Phamacology, Memorial Sloan Kettering Cancer Center, New York, NY, USA
| | - Dawn M Carone
- Department of Biology, Swarthmore College, Swarthmore, PA, USA.
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34
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Widespread organ tolerance to Xist loss and X reactivation except under chronic stress in the gut. Proc Natl Acad Sci U S A 2020; 117:4262-4272. [PMID: 32041873 DOI: 10.1073/pnas.1917203117] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Long thought to be dispensable after establishing X chromosome inactivation (XCI), Xist RNA is now known to also maintain the inactive X (Xi). To what extent somatic X reactivation causes physiological abnormalities is an active area of inquiry. Here, we use multiple mouse models to investigate in vivo consequences. First, when Xist is deleted systemically in post-XCI embryonic cells using the Meox2-Cre driver, female pups exhibit no morbidity or mortality despite partial X reactivation. Second, when Xist is conditionally deleted in epithelial cells using Keratin14-Cre or in B cells using CD19-Cre, female mice have a normal life span without obvious illness. Third, when Xist is deleted in gut using Villin-Cre, female mice remain healthy despite significant X-autosome dosage imbalance. Finally, when the gut is acutely stressed by azoxymethane/dextran sulfate (AOM/DSS) exposure, both Xist-deleted and wild-type mice develop gastrointestinal tumors. Intriguingly, however, under prolonged stress, mutant mice develop larger tumors and have a higher tumor burden. The effect is female specific. Altogether, these observations reveal a surprising systemic tolerance to Xist loss but importantly reveal that Xist and XCI are protective to females during chronic stress.
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35
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Abstract
The non-coding RNA Xist regulates the process of X chromosome inactivation, in which one of the two X chromosomes present in cells of early female mammalian embryos is selectively and coordinately shut down. Remarkably Xist RNA functions in cis, affecting only the chromosome from which it is transcribed. This feature is attributable to the unique propensity of Xist RNA to accumulate over the territory of the chromosome on which it is synthesized, contrasting with the majority of RNAs that are rapidly exported out of the cell nucleus. In this review I provide an overview of the progress that has been made towards understanding localized accumulation of Xist RNA, drawing attention to evidence that some other non-coding RNAs probably function in a highly analogous manner. I describe a simple model for localized accumulation of Xist RNA and discuss key unresolved questions that need to be addressed in future studies.
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Affiliation(s)
- Neil Brockdorff
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
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36
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Syrett CM, Sierra I, Beethem ZT, Dubin AH, Anguera MC. Loss of epigenetic modifications on the inactive X chromosome and sex-biased gene expression profiles in B cells from NZB/W F1 mice with lupus-like disease. J Autoimmun 2019; 107:102357. [PMID: 31780316 DOI: 10.1016/j.jaut.2019.102357] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 10/30/2019] [Accepted: 11/01/2019] [Indexed: 12/29/2022]
Abstract
The mechanisms underlying the female-bias in autoimmunity are poorly understood. The contribution of genetic and epigenetic factors from the inactive X chromosome (Xi) are beginning to emerge as critical mediators of autoimmunity in females. Here, we ask how epigenetic features of the Xi change during disease development in B cells from the NZB/W F1 spontaneous mouse model of lupus, which is female-biased. We find that Xist RNA becomes increasingly mislocalized from the Xi with disease onset. While NZB/W F1 naïve B cells have H3K27me3 foci on the Xi, which are missing from healthy C57BL/6 and BALB/c mice, these foci are progressively lost in stimulated B cells during disease. Using single-molecule RNA FISH, we show that the X-linked gene Tlr7 is biallelically expressed in ~20% of NZB/W F1 B cells, and that the amount of biallelic expression does not change with disease. We also present sex-specific gene expression profiles for diseased NZB/W F1 B cells, and find female-specific upregulation of 20 genes, including the autoimmunity-related genes Cxcl13, Msr1, Igj, and Prdm1. Together, these studies provide important insight into the loss of epigenetic modifications from the Xi and changes with gene expression in a mouse model of female-biased SLE.
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Affiliation(s)
- Camille M Syrett
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Isabel Sierra
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Zachary T Beethem
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Aimee H Dubin
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Montserrat C Anguera
- Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA.
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37
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Schertzer MD, Braceros KCA, Starmer J, Cherney RE, Lee DM, Salazar G, Justice M, Bischoff SR, Cowley DO, Ariel P, Zylka MJ, Dowen JM, Magnuson T, Calabrese JM. lncRNA-Induced Spread of Polycomb Controlled by Genome Architecture, RNA Abundance, and CpG Island DNA. Mol Cell 2019; 75:523-537.e10. [PMID: 31256989 PMCID: PMC6688959 DOI: 10.1016/j.molcel.2019.05.028] [Citation(s) in RCA: 85] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 04/10/2019] [Accepted: 05/17/2019] [Indexed: 01/28/2023]
Abstract
Long noncoding RNAs (lncRNAs) cause Polycomb repressive complexes (PRCs) to spread over broad regions of the mammalian genome. We report that in mouse trophoblast stem cells, the Airn and Kcnq1ot1 lncRNAs induce PRC-dependent chromatin modifications over multi-megabase domains. Throughout the Airn-targeted domain, the extent of PRC-dependent modification correlated with intra-nuclear distance to the Airn locus, preexisting genome architecture, and the abundance of Airn itself. Specific CpG islands (CGIs) displayed characteristics indicating that they nucleate the spread of PRCs upon exposure to Airn. Chromatin environments surrounding Xist, Airn, and Kcnq1ot1 suggest common mechanisms of PRC engagement and spreading. Our data indicate that lncRNA potency can be tightly linked to lncRNA abundance and that within lncRNA-targeted domains, PRCs are recruited to CGIs via lncRNA-independent mechanisms. We propose that CGIs that autonomously recruit PRCs interact with lncRNAs and their associated proteins through three-dimensional space to nucleate the spread of PRCs in lncRNA-targeted domains.
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Affiliation(s)
- Megan D Schertzer
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Keean C A Braceros
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA; Curriculum in Mechanistic, Interdisciplinary Studies of Biological Systems, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Joshua Starmer
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Rachel E Cherney
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - David M Lee
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA; Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Gabriela Salazar
- Department of Cell Biology and Physiology and UNC Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Megan Justice
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA; Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Steven R Bischoff
- Animal Models Core, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Dale O Cowley
- Animal Models Core, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Pablo Ariel
- Microscopy Services Laboratory and Department of Pathology and Laboratory Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Mark J Zylka
- Department of Cell Biology and Physiology and UNC Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jill M Dowen
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA; Integrative Program for Biological and Genome Sciences, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, USA; Department of Biology, University of North Carolina, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Terry Magnuson
- Department of Genetics, University of North Carolina, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - J Mauro Calabrese
- Department of Pharmacology, University of North Carolina, Chapel Hill, NC 27599, USA; Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA.
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38
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Matsuno Y, Yamashita T, Wagatsuma M, Yamakage H. Convergence in LINE-1 nucleotide variations can benefit redundantly forming triplexes with lncRNA in mammalian X-chromosome inactivation. Mob DNA 2019; 10:33. [PMID: 31384315 PMCID: PMC6664574 DOI: 10.1186/s13100-019-0173-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 07/08/2019] [Indexed: 01/01/2023] Open
Abstract
Background Associations between X-inactive transcript (Xist)–long noncoding RNA (lncRNA) and chromatin are critical intermolecular interactions in the X-chromosome inactivation (XCI) process. Despite high-resolution analyses of the Xist RNA-binding sites, specific interaction sequences are yet to be identified. Based on elusive features of the association between Xist RNA and chromatin and the possible existence of multiple low-affinity binding sites in Xist RNA, we defined short motifs (≥5 nucleotides), termed as redundant UC/TC (r-UC/TC) or AG (r-AG) motifs, which may help in the mediation of triplex formation between the lncRNAs and duplex DNA. Results The study showed that r-UC motifs are densely dispersed throughout mouse and human Xist/XIST RNAs, whereas r-AG motifs are even more densely dispersed along opossum RNA-on-the-silent X (Rsx) RNA, and also along both full-length and truncated long interspersed nuclear elements (LINE-1s, L1s) of the three species. Predicted secondary structures of the lncRNAs showed that the length range of these sequence motifs available for forming triplexes was even shorter, mainly 5- to 9-nucleotides long. Quartz crystal microbalance (QCM) measurements and Monte Carlo (MC) simulations indicated that minimum-length motifs can reinforce the binding state by increasing the copy number of the motifs in the same RNA or DNA molecule. Further, r-AG motifs in L1s had a similar length-distribution pattern, regardless of the similarities in the length or sequence of L1s across the three species; this also applies to high-frequency mutations in r-AG motifs, which suggests convergence in L1 sequence variations. Conclusions Multiple short motifs in both RNA and duplex DNA molecules could be brought together to form triplexes with either Hoogsteen or reverse Hoogsteen hydrogen bonding, by which their associations are cooperatively enhanced. This novel triplex interaction could be involved in associations between lncRNA and chromatin in XCI, particularly at the sites of L1s. Potential binding of Xist/XIST/Rsx RNAs specifically at L1s is most likely preserved through the r-AG motifs conserved in mammalian L1s through convergence in L1 nucleotide variations and by maintaining a particular r-UC/r-AG motif ratio in each of these lncRNAs, irrespective of their poorly conserved sequences. Electronic supplementary material The online version of this article (10.1186/s13100-019-0173-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yoko Matsuno
- 1Division of Clinical Preventive Medicine, Niigata University, Niigata, Japan
| | - Takefumi Yamashita
- 2Laboratory for Systems Biology and Medicine, Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo, Japan
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Lee DM, Trotman JB, Cherney RE, Inoue K, Schertzer MD, Bischoff SR, Cowley DO, Calabrese JM. RETRACTED: A 5' fragment of Xist can sequester RNA produced from adjacent genes on chromatin. Nucleic Acids Res 2019; 47:7049-7062. [PMID: 31114903 PMCID: PMC6648342 DOI: 10.1093/nar/gkz432] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2019] [Revised: 04/18/2019] [Accepted: 05/09/2019] [Indexed: 12/15/2022] Open
Abstract
Xist requires Repeat-A, a protein-binding module in its first two kilobases (2kb), to repress transcription. We report that when expressed as a standalone transcript in mouse embryonic stem cells (ESCs), the first 2kb of Xist (Xist-2kb) does not induce transcriptional silencing. Instead, Xist-2kb sequesters RNA produced from adjacent genes on chromatin. Sequestration does not spread beyond adjacent genes, requires the same sequence elements in Repeat-A that full-length Xist requires to repress transcription and can be induced by lncRNAs with similar sequence composition to Xist-2kb. We did not detect sequestration by full-length Xist, but we did detect it by mutant forms of Xist with attenuated transcriptional silencing capability. Xist-2kb associated with SPEN, a Repeat-A binding protein required for Xist-induced transcriptional silencing, but SPEN was not necessary for sequestration. Thus, when expressed in mouse ESCs, a 5' fragment of Xist that contains Repeat-A sequesters RNA from adjacent genes on chromatin and associates with the silencing factor SPEN, but it does not induce transcriptional silencing. Instead, Xist-induced transcriptional silencing requires synergy between Repeat-A and additional sequence elements in Xist. We propose that sequestration is mechanistically related to the Repeat-A dependent stabilization and tethering of Xist near actively transcribed regions of chromatin.
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Affiliation(s)
- David M Lee
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jackson B Trotman
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Rachel E Cherney
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Kaoru Inoue
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Megan D Schertzer
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
- Curriculum in Genetics and Molecular Biology, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Steven R Bischoff
- Animal Models Core, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Dale O Cowley
- Animal Models Core, University of North Carolina, Chapel Hill, NC 27599, USA
| | - J Mauro Calabrese
- Department of Pharmacology and Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
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Li Y, Ren Y, Wang Y, Tan Y, Wang Q, Cai J, Zhou J, Yang C, Zhao K, Yi K, Jin W, Wang L, Liu M, Yang J, Li M, Kang C. A Compound AC1Q3QWB Selectively Disrupts HOTAIR-Mediated Recruitment of PRC2 and Enhances Cancer Therapy of DZNep. Theranostics 2019; 9:4608-4623. [PMID: 31367244 PMCID: PMC6643429 DOI: 10.7150/thno.35188] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Accepted: 05/21/2019] [Indexed: 12/22/2022] Open
Abstract
Over 20% of cancer 'driver' genes encode chromatin regulators. Long noncoding RNAs (lincRNAs), which are dysregulated in various cancers, play a critical role in chromatin dynamics and gene regulation by interacting with key epigenetic regulators. It has been previously reported that the lincRNA HOTAIR mediates recruitment of polycomb repressive complex 2 (PRC2) leading to aberrant transcriptional silencing of tumor suppressor genes in glioma and breast cancer. Thus, lincRNA HOTAIR can serve as a promising therapeutic target. Herein, we identified a small-molecule compound AC1Q3QWB (AQB) as a selective and efficient disruptor of HOTAIR-EZH2 interaction, resulting in blocking of PRC2 recruitment and increasing tumor suppressors expression. Methods: Molecular docking and high-throughput screening were performed to identify the small compound, AQB. RIP and ChIRP assays were carried to assess the selective interference of AQB with the HOTAIR-EZH2 interaction. The effects of AQB on tumor malignancy were evaluated in a variety of cancer cell lines and orthotopic breast cancer models. The combination therapy of AQB and 3-Deazaneplanocin A (DZNep), an inhibitor of the histone methyltransferase EZH2 was used in vitro and in orthotopic breast cancer and glioblastoma patient-derived xenograft (PDX) models. Results: Tumor cells highly expressing HOTAIR and EZH2 were sensitive to AQB. APC2, as one of the target genes, was significantly up-regulated by AQB and led to degradation of β-catenin resulting in suppression of Wnt/β-catenin signaling which may contribute to inhibition of tumor growth and metastasis in vitro and in orthotopic breast cancer models. Remarkably, AQB enhanced the toxicity of DZNep in vitro. In orthotopic breast cancer and glioblastoma patient-derived xenografts (PDX) models, the combination of low doses of AQB and DZNep realized much better killing than DZNep treatment alone. Conclusion: AQB is a HOTAIR-EZH2 inhibitor, which blocks PRC2 recruitment and has great potential as an effective agent for targeted cancer therapy.
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Man HSJ, Marsden PA. LncRNAs and epigenetic regulation of vascular endothelium: genome positioning system and regulators of chromatin modifiers. Curr Opin Pharmacol 2019; 45:72-80. [PMID: 31125866 DOI: 10.1016/j.coph.2019.04.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Accepted: 04/15/2019] [Indexed: 12/31/2022]
Abstract
Epigenetic mechanisms regulate the cell type-specific expression of endothelial-enriched genes. A major question has been how chromatin modifiers without inherent sequence specificity can be targeted to genomic coordinates. Recently, long noncoding RNAs (lncRNAs) have emerged as candidates for specifying genomic positioning for chromatin modifiers. However, lncRNAs function by a number of mechanisms in both the nucleus and the cytoplasm. Recent studies indicate the existence of endothelial-enriched lncRNAs. This review discusses lncRNA regulation in endothelial cells with a focus on four recently described nuclear-enriched lncRNAs: MANTIS, LEENE, STEEL, and GATA6-AS. This emerging work on these lncRNAs contributes to our understanding of epigenetic regulation in the vascular endothelium with links to important themes in endothelial biology, including angiogenesis and shear stress.
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Affiliation(s)
- Hon-Sum Jeffrey Man
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada; Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada
| | - Philip A Marsden
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada; Keenan Research Centre in the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada.
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Lee HJ, Gopalappa R, Sunwoo H, Choi SW, Ramakrishna S, Lee JT, Kim HH, Nam JW. En bloc and segmental deletions of human XIST reveal X chromosome inactivation-involving RNA elements. Nucleic Acids Res 2019; 47:3875-3887. [PMID: 30783652 PMCID: PMC6486550 DOI: 10.1093/nar/gkz109] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 02/07/2019] [Accepted: 02/13/2019] [Indexed: 12/13/2022] Open
Abstract
The XIST RNA is a non-coding RNA that induces X chromosome inactivation (XCI). Unlike the mouse Xist RNA, how the human XIST RNA controls XCI in female cells is less well characterized, and its functional motifs remain unclear. To systematically decipher the XCI-involving elements of XIST RNA, 11 smaller XIST segments, including repeats A, D and E; human-specific repeat elements; the promoter; and non-repetitive exons, as well as the entire XIST gene, were homozygously deleted in K562 cells using the Cas9 nuclease and paired guide RNAs at high efficiencies, followed by high-throughput RNA sequencing and RNA fluorescence in situ hybridization experiments. Clones containing en bloc and promoter deletions that consistently displayed no XIST RNAs and a global up-regulation of X-linked genes confirmed that the deletion of XIST reactivates the inactive X chromosome. Systematic analyses of segmental deletions delineated that exon 5 harboring the non-repeat element is important for X-inactivation maintenance, whereas exons 2, 3 and 4 as well as the other repeats in exon 1 are less important, a different situation from that of mouse Xist. This Cas9-assisted dissection of XIST allowed us to understand the unique functional domains within the human XIST RNA.
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MESH Headings
- Alternative Splicing
- Animals
- Base Sequence
- CRISPR-Associated Protein 9/genetics
- CRISPR-Associated Protein 9/metabolism
- CRISPR-Cas Systems
- Chromosomes, Human, X/chemistry
- Chromosomes, Human, X/metabolism
- Clone Cells
- Exons
- Gene Editing/methods
- Genome, Human
- Humans
- K562 Cells
- Mice
- Promoter Regions, Genetic
- RNA, Long Noncoding/genetics
- RNA, Long Noncoding/metabolism
- Sequence Deletion
- Species Specificity
- Whole Genome Sequencing
- X Chromosome Inactivation
- RNA, Guide, CRISPR-Cas Systems
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Affiliation(s)
- Hyeon J Lee
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 04763, Republic of Korea
| | - Ramu Gopalappa
- Department of Pharmacology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
| | - Hongjae Sunwoo
- Department of Molecular Biology, Massachusetts General Hospital, Department of Genetics, Harvard Medical School, Boston MA 02114, USA
| | - Seo-Won Choi
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 04763, Republic of Korea
| | - Suresh Ramakrishna
- Graduate School of Biomedical Science and Engineering, Hanyang University, Seoul 04763, Republic of Korea
- College of Medicine, Hanyang University, Seoul 04763, Republic of Korea
| | - Jeannie T Lee
- Department of Molecular Biology, Massachusetts General Hospital, Department of Genetics, Harvard Medical School, Boston MA 02114, USA
| | - Hyongbum H Kim
- Department of Pharmacology, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
- Brain Korea 21 Plus Project for Medical Sciences, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
- Severance Biomedical Science Institute, Yonsei University College of Medicine, Seoul 03722, Republic of Korea
- Center for Nanomedicine, Institute for Basic Science (IBS), Seoul 34126, Republic of Korea
| | - Jin-Wu Nam
- Department of Life Science, College of Natural Sciences, Hanyang University, Seoul 04763, Republic of Korea
- Research Institute for Convergence of Basic Sciences, Hanyang University, Seoul 04763, Republic of Korea
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Abstract
A diverse catalog of long noncoding RNAs (lncRNAs), which lack protein-coding potential, are transcribed from the mammalian genome. They are emerging as important regulators in gene expression networks by controlling nuclear architecture and transcription in the nucleus and by modulating mRNA stability, translation and post-translational modifications in the cytoplasm. In this Review, we highlight recent progress in cellular functions of lncRNAs at the molecular level in mammalian cells.
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Colognori D, Sunwoo H, Kriz AJ, Wang CY, Lee JT. Xist Deletional Analysis Reveals an Interdependency between Xist RNA and Polycomb Complexes for Spreading along the Inactive X. Mol Cell 2019; 74:101-117.e10. [PMID: 30827740 DOI: 10.1016/j.molcel.2019.01.015] [Citation(s) in RCA: 112] [Impact Index Per Article: 22.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 11/21/2018] [Accepted: 01/10/2019] [Indexed: 12/16/2022]
Abstract
During X-inactivation, Xist RNA spreads along an entire chromosome to establish silencing. However, the mechanism and functional RNA elements involved in spreading remain undefined. By performing a comprehensive endogenous Xist deletion screen, we identify Repeat B as crucial for spreading Xist and maintaining Polycomb repressive complexes 1 and 2 (PRC1/PRC2) along the inactive X (Xi). Unexpectedly, spreading of these three factors is inextricably linked. Deleting Repeat B or its direct binding partner, HNRNPK, compromises recruitment of PRC1 and PRC2. In turn, ablating PRC1 or PRC2 impairs Xist spreading. Therefore, Xist and Polycomb complexes require each other to propagate along the Xi, suggesting a positive feedback mechanism between RNA initiator and protein effectors. Perturbing Xist/Polycomb spreading causes failure of de novo Xi silencing, with partial compensatory downregulation of the active X, and also disrupts topological Xi reconfiguration. Thus, Repeat B is a multifunctional element that integrates interdependent Xist/Polycomb spreading, silencing, and changes in chromosome architecture.
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Affiliation(s)
- David Colognori
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Hongjae Sunwoo
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Andrea J Kriz
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Chen-Yu Wang
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Jeannie T Lee
- Howard Hughes Medical Institute; Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Genetics, Harvard Medical School, Boston, MA 02115, USA.
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Local Tandem Repeat Expansion in Xist RNA as a Model for the Functionalisation of ncRNA. Noncoding RNA 2018; 4:ncrna4040028. [PMID: 30347781 PMCID: PMC6316617 DOI: 10.3390/ncrna4040028] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 10/15/2018] [Accepted: 10/16/2018] [Indexed: 01/08/2023] Open
Abstract
Xist, the master regulator of the X chromosome inactivation in mammals, is a 17 kb lncRNA that acts in cis to silence the majority of genes along the chromosome from which it is transcribed. The two key processes required for Xist RNA function, localisation in cis and recruitment of silencing factors, are genetically separable, at least in part. Recent studies have identified Xist RNA sequences and associated RNA-binding proteins (RBPs) that are important for these processes. Notably, several of the key Xist RNA elements correspond to local tandem repeats. In this review, I use examples to illustrate different modes whereby tandem repeat amplification has been exploited to allow orthodox RBPs to confer new functions for Xist-mediated chromosome inactivation. I further discuss the potential generality of tandem repeat expansion in the evolution of functional long non-coding RNAs (lncRNAs).
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Abstract
The past decade has witnessed an explosion in the use of super-resolution fluorescence microscopy methods in biology and other fields. Single-molecule localization microscopy (SMLM) is one of the most widespread of these methods and owes its success in large part to the ability to control the on-off state of fluorophores through various chemical, photochemical, or binding-unbinding mechanisms. We provide here a comprehensive overview of switchable fluorophores in SMLM including a detailed review of all major classes of SMLM fluorophores, and we also address strategies for labeling specimens, considerations for multichannel and live-cell imaging, potential pitfalls, and areas for future development.
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Affiliation(s)
- Honglin Li
- Department of Chemistry, University of Washington, Seattle, Washington, USA, 98195
| | - Joshua C. Vaughan
- Department of Chemistry, University of Washington, Seattle, Washington, USA, 98195
- Department of Physiology and Biophysics, University of Washington, Seattle, Washington, USA, 98195
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Balas MM, Johnson AM. Exploring the mechanisms behind long noncoding RNAs and cancer. Noncoding RNA Res 2018; 3:108-117. [PMID: 30175284 PMCID: PMC6114262 DOI: 10.1016/j.ncrna.2018.03.001] [Citation(s) in RCA: 200] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 03/23/2018] [Indexed: 02/06/2023] Open
Abstract
Over the past decade, long noncoding RNAs (lncRNAs) have been identified as significant players in gene regulation. They are often differentially expressed and widely-associated with a majority of cancer types. The aberrant expression of these transcripts has been linked to tumorigenesis, metastasis, cancer stage progression and patient survival. Despite their apparent link to cancer, it has been challenging to gain a mechanistic understanding of how they contribute to cancer, partially due the difficulty in discriminating functional RNAs from other noncoding transcription events. However, there are several well-studied lncRNAs where specific mechanisms have been more clearly defined, leading to new discoveries into how these RNAs function. One major observation that has come to light is the context-dependence of lncRNA mechanisms, where they often have unique function in specific cell types and environment. Here, we review the molecular mechanisms of lncRNAs with a focus on cancer pathways, illustrating a few informative examples. Together, this type of detailed insight will lead to a greater understanding of the potential for the application of lncRNAs as targets of cancer therapies and diagnostics.
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Affiliation(s)
- Maggie M. Balas
- Molecular Biology Program, University of Colorado Denver Anschutz Medical Campus 12801 East 17th Ave., Aurora, CO, United States
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver Anschutz Medical Campus 12801 East 17th Ave., Aurora, CO, United States
- RNA Bioscience Initiative, University of Colorado Denver Anschutz Medical Campus 12801 East 17th Ave., Aurora, CO, United States
| | - Aaron M. Johnson
- Molecular Biology Program, University of Colorado Denver Anschutz Medical Campus 12801 East 17th Ave., Aurora, CO, United States
- Department of Biochemistry and Molecular Genetics, University of Colorado Denver Anschutz Medical Campus 12801 East 17th Ave., Aurora, CO, United States
- RNA Bioscience Initiative, University of Colorado Denver Anschutz Medical Campus 12801 East 17th Ave., Aurora, CO, United States
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Blokhin I, Khorkova O, Hsiao J, Wahlestedt C. Developments in lncRNA drug discovery: where are we heading? Expert Opin Drug Discov 2018; 13:837-849. [PMID: 30078338 DOI: 10.1080/17460441.2018.1501024] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
INTRODUCTION The central dogma of molecular biology, which states that the only role of long RNA transcripts is to convey information from gene to protein, was brought into question in recent years due to discovery of the extensive presence and complex roles of long noncoding RNAs (lncRNAs). Furthermore, lncRNAs were found to be involved in pathogenesis of multiple diseases and thus represent a new class of therapeutic targets. Translational efforts in the lncRNA field have been augmented by progress in optimizing the chemistry and delivery platforms of lncRNA-targeting modalities, including oligonucleotide-based drugs and CRISPR-Cas9. Areas covered: This review covers the current advances in characterizing diversity and biological functions of lncRNA focusing on their therapeutic potential in selected therapeutic areas. Expert opinion: Due to accelerating parallel progress in lncRNA biology and lncRNA-compatible therapeutic modalities, it is likely that lncRNA-dependent mechanisms of pathogenesis will soon be targeted in various disorders, including neurological, psychiatric, cardiovascular, infectious diseases, and cancer. Significant efforts, however, are still required to better understand the biology of both lncRNAs and lncRNA-targeting drugs. Further work is needed in the areas of lncRNA nomenclature, database representation, intra/interfield communication, and education of the community at large.
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Affiliation(s)
- Ilya Blokhin
- a Center for Therapeutic Innovation and Department of Psychiatry and Behavioral Sciences , University of Miami Miller School of Medicine , Miami , FL , USA
| | | | | | - Claes Wahlestedt
- a Center for Therapeutic Innovation and Department of Psychiatry and Behavioral Sciences , University of Miami Miller School of Medicine , Miami , FL , USA
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Orr AA, Gonzalez-Rivera JC, Wilson M, Bhikha PR, Wang D, Contreras LM, Tamamis P. A high-throughput and rapid computational method for screening of RNA post-transcriptional modifications that can be recognized by target proteins. Methods 2018; 143:34-47. [DOI: 10.1016/j.ymeth.2018.01.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Revised: 01/14/2018] [Accepted: 01/26/2018] [Indexed: 12/25/2022] Open
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50
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Donlic A, Hargrove AE. Targeting RNA in mammalian systems with small molecules. WILEY INTERDISCIPLINARY REVIEWS. RNA 2018; 9:e1477. [PMID: 29726113 PMCID: PMC6002909 DOI: 10.1002/wrna.1477] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/06/2018] [Accepted: 03/06/2018] [Indexed: 12/18/2022]
Abstract
The recognition of RNA functions beyond canonical protein synthesis has challenged the central dogma of molecular biology. Indeed, RNA is now known to directly regulate many important cellular processes, including transcription, splicing, translation, and epigenetic modifications. The misregulation of these processes in disease has led to an appreciation of RNA as a therapeutic target. This potential was first recognized in bacteria and viruses, but discoveries of new RNA classes following the sequencing of the human genome have invigorated exploration of its disease-related functions in mammals. As stable structure formation is evolving as a hallmark of mammalian RNAs, the prospect of utilizing small molecules to specifically probe the function of RNA structural domains and their interactions is gaining increased recognition. To date, researchers have discovered bioactive small molecules that modulate phenotypes by binding to expanded repeats, microRNAs, G-quadruplex structures, and RNA splice sites in neurological disorders, cancers, and other diseases. The lessons learned from achieving these successes both call for additional studies and encourage exploration of the plethora of mammalian RNAs whose precise mechanisms of action remain to be elucidated. Efforts toward understanding fundamental principles of small molecule-RNA recognition combined with advances in methodology development should pave the way toward targeting emerging RNA classes such as long noncoding RNAs. Together, these endeavors can unlock the full potential of small molecule-based probing of RNA-regulated processes and enable us to discover new biology and underexplored avenues for therapeutic intervention in human disease. This article is categorized under: RNA Methods > RNA Analyses In Vitro and In Silico RNA Interactions with Proteins and Other Molecules > Small Molecule-RNA Interactions RNA in Disease and Development > RNA in Disease.
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Affiliation(s)
- Anita Donlic
- Department of Chemistry, Duke University, Durham, North Carolina
| | - Amanda E Hargrove
- Department of Chemistry, Duke University, Durham, North Carolina
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina
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