1
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Hsiao YT, Liao IH, Wu BK, Chu HPC, Hsieh CL. Probing chromatin condensation dynamics in live cells using interferometric scattering correlation spectroscopy. Commun Biol 2024; 7:763. [PMID: 38914653 PMCID: PMC11196589 DOI: 10.1038/s42003-024-06457-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2023] [Accepted: 06/14/2024] [Indexed: 06/26/2024] Open
Abstract
Chromatin organization and dynamics play important roles in governing the regulation of nuclear processes of biological cells. However, due to the constant diffusive motion of chromatin, examining chromatin nanostructures in living cells has been challenging. In this study, we introduce interferometric scattering correlation spectroscopy (iSCORS) to spatially map nanoscopic chromatin configurations within unlabeled live cell nuclei. This label-free technique captures time-varying linear scattering signals generated by the motion of native chromatin on a millisecond timescale, allowing us to deduce chromatin condensation states. Using iSCORS imaging, we quantitatively examine chromatin dynamics over extended periods, revealing spontaneous fluctuations in chromatin condensation and heterogeneous compaction levels in interphase cells, independent of cell phases. Moreover, we observe changes in iSCORS signals of chromatin upon transcription inhibition, indicating that iSCORS can probe nanoscopic chromatin structures and dynamics associated with transcriptional activities. Our scattering-based optical microscopy, which does not require labeling, serves as a powerful tool for visualizing dynamic chromatin nano-arrangements in live cells. This advancement holds promise for studying chromatin remodeling in various crucial cellular processes, such as stem cell differentiation, mechanotransduction, and DNA repair.
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Affiliation(s)
- Yi-Teng Hsiao
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan
| | - I-Hsin Liao
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan
- Institute of Molecular and Cellular Biology, National Taiwan University, Taipei, Taiwan
| | - Bo-Kuan Wu
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan
| | | | - Chia-Lung Hsieh
- Institute of Atomic and Molecular Sciences (IAMS), Academia Sinica, Taipei, Taiwan.
- Department of Physics, National Taiwan University, Taipei, Taiwan.
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2
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Senapati S, Irshad IU, Sharma AK, Kumar H. Fundamental insights into the correlation between chromosome configuration and transcription. Phys Biol 2023; 20:051002. [PMID: 37467757 DOI: 10.1088/1478-3975/ace8e5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 07/19/2023] [Indexed: 07/21/2023]
Abstract
Eukaryotic chromosomes exhibit a hierarchical organization that spans a spectrum of length scales, ranging from sub-regions known as loops, which typically comprise hundreds of base pairs, to much larger chromosome territories that can encompass a few mega base pairs. Chromosome conformation capture experiments that involve high-throughput sequencing methods combined with microscopy techniques have enabled a new understanding of inter- and intra-chromosomal interactions with unprecedented details. This information also provides mechanistic insights on the relationship between genome architecture and gene expression. In this article, we review the recent findings on three-dimensional interactions among chromosomes at the compartment, topologically associating domain, and loop levels and the impact of these interactions on the transcription process. We also discuss current understanding of various biophysical processes involved in multi-layer structural organization of chromosomes. Then, we discuss the relationships between gene expression and genome structure from perturbative genome-wide association studies. Furthermore, for a better understanding of how chromosome architecture and function are linked, we emphasize the role of epigenetic modifications in the regulation of gene expression. Such an understanding of the relationship between genome architecture and gene expression can provide a new perspective on the range of potential future discoveries and therapeutic research.
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Affiliation(s)
- Swayamshree Senapati
- School of Basic Sciences, Indian Institute of Technology, Bhubaneswar, Argul, Odisha 752050, India
| | - Inayat Ullah Irshad
- Department of Physics, Indian Institute of Technology, Jammu, Jammu 181221, India
| | - Ajeet K Sharma
- Department of Physics, Indian Institute of Technology, Jammu, Jammu 181221, India
- Department of Biosciences and Bioengineering, Indian Institute of Technology Jammu, Jammu 181221, India
| | - Hemant Kumar
- School of Basic Sciences, Indian Institute of Technology, Bhubaneswar, Argul, Odisha 752050, India
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3
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Harun A, Liu H, Song S, Asghar S, Wen X, Fang Z, Chen C. Oligonucleotide Fluorescence In Situ Hybridization: An Efficient Chromosome Painting Method in Plants. PLANTS (BASEL, SWITZERLAND) 2023; 12:2816. [PMID: 37570972 PMCID: PMC10420648 DOI: 10.3390/plants12152816] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/19/2023] [Accepted: 07/27/2023] [Indexed: 08/13/2023]
Abstract
Fluorescence in situ hybridization (FISH) is an indispensable technique for studying chromosomes in plants. However, traditional FISH methods, such as BAC, rDNA, tandem repeats, and distributed repetitive sequence probe-based FISH, have certain limitations, including difficulties in probe synthesis, low sensitivity, cross-hybridization, and limited resolution. In contrast, oligo-based FISH represents a more efficient method for chromosomal studies in plants. Oligo probes are computationally designed and synthesized for any plant species with a sequenced genome and are suitable for single and repetitive DNA sequences, entire chromosomes, or chromosomal segments. Furthermore, oligo probes used in the FISH experiment provide high specificity, resolution, and multiplexing. Moreover, oligo probes made from one species are applicable for studying other genetically and taxonomically related species whose genome has not been sequenced yet, facilitating molecular cytogenetic studies of non-model plants. However, there are some limitations of oligo probes that should be considered, such as requiring prior knowledge of the probe design process and FISH signal issues with shorter probes of background noises during oligo-FISH experiments. This review comprehensively discusses de novo oligo probe synthesis with more focus on single-copy DNA sequences, preparation, improvement, and factors that affect oligo-FISH efficiency. Furthermore, this review highlights recent applications of oligo-FISH in a wide range of plant chromosomal studies.
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Affiliation(s)
- Arrashid Harun
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Institute of Rice Industry Technology Research, College of Agricultural Sciences, Guizhou University, Guiyang 550025, China;
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Institute of Agro-Bioengineering, College of Life Science, Guizhou University, Guiyang 550025, China; (S.A.); (X.W.)
- National Key Laboratory for Germplasm Innovation and Utilization for Fruit and Vegetable Horticultural Crops, Hubei Hongshan Laboratory, Wuhan 430070, China; (H.L.); (S.S.)
| | - Hui Liu
- National Key Laboratory for Germplasm Innovation and Utilization for Fruit and Vegetable Horticultural Crops, Hubei Hongshan Laboratory, Wuhan 430070, China; (H.L.); (S.S.)
| | - Shipeng Song
- National Key Laboratory for Germplasm Innovation and Utilization for Fruit and Vegetable Horticultural Crops, Hubei Hongshan Laboratory, Wuhan 430070, China; (H.L.); (S.S.)
| | - Sumeera Asghar
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Institute of Agro-Bioengineering, College of Life Science, Guizhou University, Guiyang 550025, China; (S.A.); (X.W.)
- National Key Laboratory for Germplasm Innovation and Utilization for Fruit and Vegetable Horticultural Crops, Hubei Hongshan Laboratory, Wuhan 430070, China; (H.L.); (S.S.)
| | - Xiaopeng Wen
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Institute of Agro-Bioengineering, College of Life Science, Guizhou University, Guiyang 550025, China; (S.A.); (X.W.)
| | - Zhongming Fang
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Institute of Rice Industry Technology Research, College of Agricultural Sciences, Guizhou University, Guiyang 550025, China;
| | - Chunli Chen
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Institute of Rice Industry Technology Research, College of Agricultural Sciences, Guizhou University, Guiyang 550025, China;
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), Institute of Agro-Bioengineering, College of Life Science, Guizhou University, Guiyang 550025, China; (S.A.); (X.W.)
- National Key Laboratory for Germplasm Innovation and Utilization for Fruit and Vegetable Horticultural Crops, Hubei Hongshan Laboratory, Wuhan 430070, China; (H.L.); (S.S.)
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4
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Lu S, Hou Y, Zhang XE, Gao Y. Live cell imaging of DNA and RNA with fluorescent signal amplification and background reduction techniques. Front Cell Dev Biol 2023; 11:1216232. [PMID: 37342234 PMCID: PMC10277805 DOI: 10.3389/fcell.2023.1216232] [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: 05/03/2023] [Accepted: 05/24/2023] [Indexed: 06/22/2023] Open
Abstract
Illuminating DNA and RNA dynamics in live cell can elucidate their life cycle and related biochemical activities. Various protocols have been developed for labeling the regions of interest in DNA and RNA molecules with different types of fluorescent probes. For example, CRISPR-based techniques have been extensively used for imaging genomic loci. However, some DNA and RNA molecules can still be difficult to tag and observe dynamically, such as genomic loci in non-repetitive regions. In this review, we will discuss the toolbox of techniques and methodologies that have been developed for imaging DNA and RNA. We will also introduce optimized systems that provide enhanced signal intensity or low background fluorescence for those difficult-to-tag molecules. These strategies can provide new insights for researchers when designing and using techniques to visualize DNA or RNA molecules.
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Affiliation(s)
- Song Lu
- Center for Advanced Measurement Science, National Institute of Metrology, Beijing, China
| | - Yu Hou
- Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Xian-En Zhang
- Faculty of Synthetic Biology, Shenzhen Institute of Advanced Technology, Shenzhen, China
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yunhua Gao
- Center for Advanced Measurement Science, National Institute of Metrology, Beijing, China
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5
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Pradhan S, Apaydin S, Bucevičius J, Gerasimaitė R, Kostiuk G, Lukinavičius G. Sequence-specific DNA labelling for fluorescence microscopy. Biosens Bioelectron 2023; 230:115256. [PMID: 36989663 DOI: 10.1016/j.bios.2023.115256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 03/04/2023] [Accepted: 03/21/2023] [Indexed: 03/29/2023]
Abstract
The preservation of nucleus structure during microscopy imaging is a top priority for understanding chromatin organization, genome dynamics, and gene expression regulation. In this review, we summarize the sequence-specific DNA labelling methods that can be used for imaging in fixed and/or living cells without harsh treatment and DNA denaturation: (i) hairpin polyamides, (ii) triplex-forming oligonucleotides, (iii) dCas9 proteins, (iv) transcription activator-like effectors (TALEs) and (v) DNA methyltransferases (MTases). All these techniques are capable of identifying repetitive DNA loci and robust probes are available for telomeres and centromeres, but visualizing single-copy sequences is still challenging. In our futuristic vision, we see gradual replacement of the historically important fluorescence in situ hybridization (FISH) by less invasive and non-destructive methods compatible with live cell imaging. Combined with super-resolution fluorescence microscopy, these methods will open the possibility to look into unperturbed structure and dynamics of chromatin in living cells, tissues and whole organisms.
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6
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Peng Q, Huang Z, Sun K, Liu Y, Yoon CW, Harrison RES, Schmitt DL, Zhu L, Wu Y, Tasan I, Zhao H, Zhang J, Zhong S, Chien S, Wang Y. Engineering inducible biomolecular assemblies for genome imaging and manipulation in living cells. Nat Commun 2022; 13:7933. [PMID: 36566209 PMCID: PMC9789998 DOI: 10.1038/s41467-022-35504-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 12/06/2022] [Indexed: 12/25/2022] Open
Abstract
Genome architecture and organization play critical roles in cell life. However, it remains largely unknown how genomic loci are dynamically coordinated to regulate gene expression and determine cell fate at the single cell level. We have developed an inducible system which allows Simultaneous Imaging and Manipulation of genomic loci by Biomolecular Assemblies (SIMBA) in living cells. In SIMBA, the human heterochromatin protein 1α (HP1α) is fused to mCherry and FRB, which can be induced to form biomolecular assemblies (BAs) with FKBP-scFv, guided to specific genomic loci by a nuclease-defective Cas9 (dCas9) or a transcriptional factor (TF) carrying tandem repeats of SunTag. The induced BAs can not only enhance the imaging signals at target genomic loci using a single sgRNA, either at repetitive or non-repetitive sequences, but also recruit epigenetic modulators such as histone methyltransferase SUV39H1 to locally repress transcription. As such, SIMBA can be applied to simultaneously visualize and manipulate, in principle, any genomic locus with controllable timing in living cells.
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Affiliation(s)
- Qin Peng
- Department of Bioengineering, Institute of Engineering in Medicine, University of California, La Jolla, CA, 92093-0435, USA.
- Institute of Systems and Physical Biology, Shenzhen Bay Laboratory, Shenzhen, 518132, P. R. China.
| | - Ziliang Huang
- Department of Bioengineering, Institute of Engineering in Medicine, University of California, La Jolla, CA, 92093-0435, USA
| | - Kun Sun
- Institute of Cancer Research, Shenzhen Bay Laboratory, Shenzhen, 518132, P. R. China
| | - Yahan Liu
- Department of Bioengineering, Institute of Engineering in Medicine, University of California, La Jolla, CA, 92093-0435, USA
| | - Chi Woo Yoon
- Department of Bioengineering, Institute of Engineering in Medicine, University of California, La Jolla, CA, 92093-0435, USA
| | - Reed E S Harrison
- Department of Bioengineering, Institute of Engineering in Medicine, University of California, La Jolla, CA, 92093-0435, USA
| | - Danielle L Schmitt
- Department of Pharmacology, University of California, La Jolla, CA, 92093-0435, USA
| | - Linshan Zhu
- Department of Bioengineering, Institute of Engineering in Medicine, University of California, La Jolla, CA, 92093-0435, USA
| | - Yiqian Wu
- Department of Bioengineering, Institute of Engineering in Medicine, University of California, La Jolla, CA, 92093-0435, USA
| | - Ipek Tasan
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Huimin Zhao
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Chemical and Biomolecular Engineering, University of Illinois, Urbana-Champaign, Urbana, IL, 61801, USA
| | - Jin Zhang
- Department of Pharmacology, University of California, La Jolla, CA, 92093-0435, USA
| | - Sheng Zhong
- Department of Bioengineering, Institute of Engineering in Medicine, University of California, La Jolla, CA, 92093-0435, USA
| | - Shu Chien
- Department of Bioengineering, Institute of Engineering in Medicine, University of California, La Jolla, CA, 92093-0435, USA
- Department of Medicine, University of California, La Jolla, CA, 92093-0435, USA
| | - Yingxiao Wang
- Department of Bioengineering, Institute of Engineering in Medicine, University of California, La Jolla, CA, 92093-0435, USA.
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7
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Viushkov VS, Lomov NA, Rubtsov MA, Vassetzky YS. Visualizing the Genome: Experimental Approaches for Live-Cell Chromatin Imaging. Cells 2022; 11:cells11244086. [PMID: 36552850 PMCID: PMC9776900 DOI: 10.3390/cells11244086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 12/07/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022] Open
Abstract
Over the years, our vision of the genome has changed from a linear molecule to that of a complex 3D structure that follows specific patterns and possesses a hierarchical organization. Currently, genomics is becoming "four-dimensional": our attention is increasingly focused on the study of chromatin dynamics over time, in the fourth dimension. Recent methods for visualizing the movements of chromatin loci in living cells by targeting fluorescent proteins can be divided into two groups. The first group requires the insertion of a special sequence into the locus of interest, to which proteins that recognize the sequence are recruited (e.g., FROS and ParB-INT methods). In the methods of the second approach, "programmed" proteins are targeted to the locus of interest (i.e., systems based on CRISPR/Cas, TALE, and zinc finger proteins). In the present review, we discuss these approaches, examine their strengths and weaknesses, and identify the key scientific problems that can be studied using these methods.
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Affiliation(s)
- Vladimir S. Viushkov
- Department of Molecular Biology, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Nikolai A. Lomov
- Department of Molecular Biology, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Mikhail A. Rubtsov
- Department of Molecular Biology, Faculty of Biology, Lomonosov Moscow State University, 119234 Moscow, Russia
- Department of Biochemistry, Center for Industrial Technologies and Entrepreneurship, I.M. Sechenov First Moscow State Medical University (Sechenov University), 119435 Moscow, Russia
| | - Yegor S. Vassetzky
- CNRS UMR9018, Université Paris-Saclay, Gustave Roussy, 94805 Villejuif, France
- Koltzov Institute of Developmental Biology, Russian Academy of Sciences, 119334 Moscow, Russia
- Correspondence:
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8
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Van Tricht C, Voet T, Lammertyn J, Spasic D. Imaging the unimaginable: leveraging signal generation of CRISPR-Cas for sensitive genome imaging. Trends Biotechnol 2022; 41:769-784. [PMID: 36369053 DOI: 10.1016/j.tibtech.2022.10.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 09/29/2022] [Accepted: 10/11/2022] [Indexed: 11/10/2022]
Abstract
Fluorescence in situ hybridization (FISH) is the gold standard for visualizing genomic DNA in fixed cells and tissues, but it is incompatible with live-cell imaging, and its combination with RNA imaging is challenging. Consequently, due to its capacity to bind double-stranded DNA (dsDNA) and design flexibility, the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated protein 9 (CRISPR-Cas9) technology has sparked enormous interest over the past decade. In this review, we describe various nucleic acid (NA)- and protein-based (amplified) signal generation methods that achieve imaging of repetitive and single-copy sequences, and even single-nucleotide variants (SNVs), next to highly multiplexed as well as dynamic imaging in live cells. With future progress in the field, the CRISPR-(d)Cas9-based technology promises to break through as a next-generation cell-imaging technique.
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9
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Kang K, Song Y, Kim I, Kim TJ. Therapeutic Applications of the CRISPR-Cas System. Bioengineering (Basel) 2022; 9:bioengineering9090477. [PMID: 36135023 PMCID: PMC9495783 DOI: 10.3390/bioengineering9090477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/08/2022] [Accepted: 09/13/2022] [Indexed: 11/16/2022] Open
Abstract
The clustered regularly interspaced palindromic repeat (CRISPR)-Cas system has revolutionized genetic engineering due to its simplicity, stability, and precision since its discovery. This technology is utilized in a variety of fields, from basic research in medicine and biology to medical diagnosis and treatment, and its potential is unbounded as new methods are developed. The review focused on medical applications and discussed the most recent treatment trends and limitations, with an emphasis on CRISPR-based therapeutics for infectious disease, oncology, and genetic disease, as well as CRISPR-based diagnostics, screening, immunotherapy, and cell therapy. Given its promising results, the successful implementation of the CRISPR-Cas system in clinical practice will require further investigation into its therapeutic applications.
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Affiliation(s)
- Kyungmin Kang
- College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 06591, Korea
| | - Youngjae Song
- College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 06591, Korea
| | - Inho Kim
- College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 06591, Korea
| | - Tae-Jung Kim
- Department of Hospital Pathology, Yeouido St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, 10, 63-ro, Yeongdeungpo-gu, Seoul 07345, Korea
- Correspondence: ; Tel.: +82-2-3779-2157
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10
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Li J, Pertsinidis A. Nanoscale nuclear environments, fine-scale 3D genome organization and transcription regulation. CURRENT OPINION IN SYSTEMS BIOLOGY 2022; 31:100436. [PMID: 37091742 PMCID: PMC10118054 DOI: 10.1016/j.coisb.2022.100436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Decades of in vitro biochemical reconstitution, genetics and structural biology studies have established a vast knowledge base on the molecular mechanisms of chromatin regulation and transcription. A remaining challenge is to understand how these intricate biochemical systems operate in the context of the 3D genome organization and in the crowded and compartmentalized nuclear milieu. Here we review recent progress in this area based on high-resolution imaging approaches.
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Affiliation(s)
- Jieru Li
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, NY 10065, USA
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11
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Needham J, Metzis V. Heads or tails: Making the spinal cord. Dev Biol 2022; 485:80-92. [DOI: 10.1016/j.ydbio.2022.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 12/15/2021] [Accepted: 03/02/2022] [Indexed: 12/14/2022]
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12
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Safdar S, Driesen S, Leirs K, De Sutter D, Eyckerman S, Lammertyn J, Spasic D. Engineered tracrRNA for enabling versatile CRISPR-dCas9-based biosensing concepts. Biosens Bioelectron 2022; 206:114140. [PMID: 35247858 DOI: 10.1016/j.bios.2022.114140] [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: 10/20/2021] [Revised: 02/22/2022] [Accepted: 02/26/2022] [Indexed: 12/26/2022]
Abstract
In recent years, CRISPR-Cas (stands for: clustered regularly interspaced short palindromic repeats - CRISPR associated protein) based technologies have gained increasing attention in the biosensing field. Thanks to excellent sequence specificity, their use is of particular interest for detecting nucleic acid (NA) targets. In this context, signal generation and amplification can be realized by employing the cis-cleavage activity of the Cas9 protein, although other options involving the catalytically inactive dead Cas9 (dCas9) are increasingly explored. The latter are however mostly based on complex protein engineering processes and often lack efficient signal amplification. Here we showed for the first time that flexible signal generation and amplification properties can be integrated into the CRISPR-dCas9 complex based on a straightforward incorporation of a DNA sequence into the trans-activating CRISPR RNA (tracrRNA). The intrinsic nuclease activity of the engineered complex remained conserved, while the incorporated DNA stretch enabled two modes of amplified fluorescent signal generation: (1) as an RNA-cleaving DNA-based enzyme (DNAzyme) or (2) as hybridization site for biotinylated DNA probes, allowing subsequent enzyme labeling. Both signal generation strategies were demonstrated in solution as well as while coupled to a solid surface. Finally, in a proof of concept bioassay, we demonstrated the successful detection of single stranded DNA on magnetic microbeads using the engineered CRISPR-dCas9 complex. Thanks to the flexibility of incorporating different NA-based signal generation and amplification strategies, this novel NA engineering approach holds enormous promise for many new CRISPR-based biosensing applications.
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Affiliation(s)
- Saba Safdar
- Department of Biosystems, Biosensors Group, KU Leuven, Willem de Croylaan 42, 3001, Leuven, Belgium
| | - Seppe Driesen
- Department of Biosystems, Biosensors Group, KU Leuven, Willem de Croylaan 42, 3001, Leuven, Belgium
| | - Karen Leirs
- Department of Biosystems, Biosensors Group, KU Leuven, Willem de Croylaan 42, 3001, Leuven, Belgium
| | - Delphine De Sutter
- VIB Center for Medical Biotechnology, UGent Department of Biomolecular Medicine, Technologiepark 75, Zwijnaarde, Belgium
| | - Sven Eyckerman
- VIB Center for Medical Biotechnology, UGent Department of Biomolecular Medicine, Technologiepark 75, Zwijnaarde, Belgium
| | - Jeroen Lammertyn
- Department of Biosystems, Biosensors Group, KU Leuven, Willem de Croylaan 42, 3001, Leuven, Belgium.
| | - Dragana Spasic
- Department of Biosystems, Biosensors Group, KU Leuven, Willem de Croylaan 42, 3001, Leuven, Belgium
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13
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Emerging strategies for the genetic dissection of gene functions, cell types, and neural circuits in the mammalian brain. Mol Psychiatry 2022; 27:422-435. [PMID: 34561609 DOI: 10.1038/s41380-021-01292-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 08/17/2021] [Accepted: 09/08/2021] [Indexed: 02/08/2023]
Abstract
The mammalian brain is composed of a large number of highly diverse cell types with different molecular, anatomical, and functional features. Distinct cellular identities are generated during development under the regulation of intricate genetic programs and manifested through unique combinations of gene expression. Recent advancements in our understanding of the molecular and cellular mechanisms underlying the assembly, function, and pathology of the brain circuitry depend on the invention and application of genetic strategies that engage intrinsic gene regulatory mechanisms. Here we review the strategies for gene regulation on DNA, RNA, and protein levels and their applications in cell type targeting and neural circuit dissection. We highlight newly emerged strategies and emphasize the importance of combinatorial approaches. We also discuss the potential caveats and pitfalls in current methods and suggest future prospects to improve their comprehensiveness and versatility.
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14
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Chaudhary N, Im JK, Nho SH, Kim H. Visualizing Live Chromatin Dynamics through CRISPR-Based Imaging Techniques. Mol Cells 2021; 44:627-636. [PMID: 34588320 PMCID: PMC8490199 DOI: 10.14348/molcells.2021.2254] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 11/27/2022] Open
Abstract
The three-dimensional organization of chromatin and its time-dependent changes greatly affect virtually every cellular function, especially DNA replication, genome maintenance, transcription regulation, and cell differentiation. Sequencing-based techniques such as ChIP-seq, ATAC-seq, and Hi-C provide abundant information on how genomic elements are coupled with regulatory proteins and functionally organized into hierarchical domains through their interactions. However, visualizing the time-dependent changes of such organization in individual cells remains challenging. Recent developments of CRISPR systems for site-specific fluorescent labeling of genomic loci have provided promising strategies for visualizing chromatin dynamics in live cells. However, there are several limiting factors, including background signals, off-target binding of CRISPR, and rapid photobleaching of the fluorophores, requiring a large number of target-bound CRISPR complexes to reliably distinguish the target-specific foci from the background. Various modifications have been engineered into the CRISPR system to enhance the signal-to-background ratio and signal longevity to detect target foci more reliably and efficiently, and to reduce the required target size. In this review, we comprehensively compare the performances of recently developed CRISPR designs for improved visualization of genomic loci in terms of the reliability of target detection, the ability to detect small repeat loci, and the allowed time of live tracking. Longer observation of genomic loci allows the detailed identification of the dynamic characteristics of chromatin. The diffusion properties of chromatin found in recent studies are reviewed, which provide suggestions for the underlying biological processes.
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Affiliation(s)
- Narendra Chaudhary
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Jae-Kyeong Im
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Si-Hyeong Nho
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Hajin Kim
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
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