Table of Contents
Overview
Definition of Chromatin
Chromatin is a complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells. It exists in two primary forms: euchromatin and heterochromatin, each playing distinct roles in gene regulation and expression. Euchromatin is characterized by a loose and open structure, which allows for active gene expression and transcription, making it accessible to the transcription machinery.[31.1] In contrast, heterochromatin is densely packed and transcriptionally inactive, keeping the underlying DNA inaccessible and silenced.[30.1] Heterochromatin is essential for various cellular functions, including the regulation of gene expression during development and cellular differentiation. It plays a fundamental role in maintaining genome integrity and silencing repetitive DNA elements, with histone modifications being crucial for establishing heterochromatin domains.[27.1] Additionally, heterochromatin-like structures are involved in the stable inactivation of developmental regulators, such as the homeotic gene clusters in Drosophila.[28.1] The interplay between heterochromatin and euchromatin is vital for guiding cellular development and differentiation, as cells transition from pluripotent stem cells to specialized cell types.[32.1] However, the role of heterochromatin can change with age, potentially leading to misregulation of gene expression and contributing to aging-associated phenotypes.[29.1] Overall, the distinctions between heterochromatin and euchromatin are crucial for understanding gene regulation and the biological processes that depend on these chromatin forms.Structure and Function
Chromatin is a complex of DNA and proteins, primarily histones, found in eukaryotic cells. Its primary function is to package long DNA molecules into more compact and denser structures, allowing them to fit within the nucleus.[2.1] Initially, chromatin was thought to merely provide color to the cell nucleus; however, it is now recognized as a significant controller of DNA expression, playing a crucial role in various cellular processes, including DNA replication.[4.1] The structure of chromosomes, which is influenced by chromatin, is essential for the proper replication of DNA.[4.1] Additionally, the alteration of chromatin structure through the addition of chemical groups to histone residues, such as phosphate and acetyl groups, regulates gene expression and facilitates DNA repair processes.[2.1] The basic structural unit of chromatin is the nucleosome, which consists of a segment of DNA wrapped around a core of histone proteins. This arrangement creates a "beads on a string" structure, where nucleosomes further coil and condense to form the fibrous material known as chromatin.[7.1] Chromatin can be classified into two main types based on its condensation: heterochromatin, which is tightly packed and generally transcriptionally inactive, and euchromatin, which is more loosely packed and accessible for transcription.[18.1] The structure and function of chromatin are essential for regulating gene expression in eukaryotic cells. Chromatin, a complex of DNA and protein, exists in two forms: heterochromatin, which is tightly packed and not actively transcribed, and euchromatin, which is loosely packed and accessible for transcription.[18.1] Chemical modifications to histone tails significantly impact gene expression by influencing the accessibility of DNA to transcription factors, as the compaction of chromatin limits this accessibility.[18.1] The dynamics of chromatin structure impose significant obstacles on transcription processes mediated by RNA polymerase II, and these dynamics are tightly regulated through mechanisms such as histone modification, chromatin remodeling, and the incorporation of histone variants.[9.1] While modifications like histone tail clipping can have pronounced effects on chromatin structure, neutral modifications such as histone methylation are less likely to directly alter chromatin architecture due to their small size and lack of charge alteration.[8.1] Overall, the regulation of chromatin structure is crucial for proper gene expression and cellular function, ensuring the correct packaging of DNA during processes such as DNA replication.[10.1] The higher-order organization of chromatin, characterized by the formation of chromatin loops ranging from a few kilobases to several megabases, plays a significant role in regulating gene expression programs. This structural organization not only serves a packaging function but also impacts gene regulation by establishing boundaries between active and inactive chromatin domains.[17.1] For instance, specific DNA elements, such as insulators, can block the action of enhancers, thereby influencing the spatial arrangement of genes and their regulatory elements.[19.1] Furthermore, the creation of accessible regions within chromatin, known as DNase I hypersensitive sites (DHSs), is crucial for the binding of transcription factors and the initiation of transcription. This process often involves the cooperative action of various transcription factors, with some specialized pioneer factors initiating the formation of these nucleosome-free regions.[20.1]In this section:
History
Early Discoveries
The history of chromatin research provides valuable insights into the evolution of scientific understanding in this field. A key lesson is the importance of proposing theories, even if they are later proven incorrect, as this iterative process is essential for advancing knowledge and fostering innovation. The development of new technologies has also been crucial, often leading to novel insights and discoveries. Interestingly, these technological advancements frequently emerge from new questions posed by researchers, illustrating the dynamic interplay between inquiry and innovation in chromatin studies.[52.1] This process has significantly shaped our understanding of gene regulation, driving further research and discovery in chromatin biology.[52.1]Evolution of Chromatin Research
The evolution of chromatin research can be traced back to the late 19th century when the concept of chromatin as a complex of nucleic acids and proteins in the cell nucleus was first developed by cytologists and biochemists. This foundational understanding set the stage for subsequent biochemical research on DNA and nuclear functions.[54.1] A pivotal figure in this early research was Friedrich Miescher, who, in 1869, discovered a substance he termed "nuclein" while studying the chemical composition of leukocytes. His work marked a significant turning point in the understanding of the molecular nature of DNA and chromatin, highlighting the intertwined history of these two critical components of genetics.[67.1] Miescher's approach was innovative for its time, as he focused on isolated cells rather than whole organs, allowing for a more precise understanding of the chemical basis of life.[68.1] His insights laid the groundwork for the dual strands of genetics that encompass both DNA and chromatin, emphasizing the importance of both information and physiological processes in heredity.[67.1] The historical narrative of chromatin research has evolved, particularly with the advent of epigenetics in the late 20th century, which has revitalized interest in chromatin modifications and their implications for gene regulation.[55.1] Technological advancements have been pivotal in the evolution of chromatin research, particularly through the development of microscopy techniques. Light microscopy has served as an enabling technology for biology, facilitating non-invasive visualization of cellular and sub-cellular structures in multiple colors, in three dimensions, and in living cells.[75.1] However, traditional light microscopy was limited in its resolution, which hindered the ability to reveal the intricate organization of DNA within the nucleus.[77.1] The emergence of advanced microscopy techniques has transformed the study of chromosome structure, allowing researchers to examine genetic material with unprecedented clarity.[77.1] This technological shift has contributed to a changing perception of chromatin, evolving from a fixed and static entity to a more dynamic and irregular structure capable of phase separation and self-organization.[76.1] Additionally, the integration of chemical and genetic tools has provided versatile methods for visualizing chromatin structure and dynamics in both fixed and live-cell contexts, which are essential for understanding gene regulation and nuclear architecture.[74.1] Overall, the history of chromatin research underscores the importance of technological innovation and the continuous evolution of methodologies in the field.[52.1]Recent Advancements
3D Chromatin Structure Analysis
Recent advancements in the analysis of 3D chromatin structure have significantly enhanced our understanding of chromatin dynamics and its functional implications. Chromatin, composed of DNA and histone proteins organized into nucleosomes, plays a crucial role in regulating genome accessibility and controlling transcription, replication, and repair by dynamically switching between open and compact states influenced by various factors, including histone post-translational modifications and interactions with chromatin modulators.[109.1] Recent studies have highlighted the importance of advanced imaging techniques such as Nuclear Magnetic Resonance (NMR) and Förster Resonance Energy Transfer (FRET) in elucidating the structural and dynamic properties of chromatin. These techniques have revealed unique molecular characteristics of nucleosomes that are often not visible through traditional methods like cryogenic electron microscopy (cryo-EM) and X-ray diffraction (XRD).[105.1] For instance, solid-state NMR spectroscopy has been particularly effective in providing atomistic information about the structure and conformational dynamics of histone core and tail domains within nucleosomes, allowing for detailed characterization of chromatin at high densities typical of cellular environments.[106.1] Moreover, the concept of phase separation in chromatin organization has emerged as a promising area of research. This phenomenon suggests that certain histone modifications and chromatin-associated proteins contribute to the formation of biomolecular condensates, which are membrane-less compartments that concentrate specific molecules, thereby influencing gene regulation.[96.1] The ability of chromatin to form distinct types of immiscible condensates based on reversible marks can confer specificity in the crowded nuclear environment, facilitating efficient gene expression and regulation.[97.1] The study of chromatin structure and dynamics has significantly advanced with the integration of advanced imaging techniques such as NMR and FRET. Understanding how biomolecules couple structural dynamics with function is at the heart of several disciplines and remains an outstanding goal in biology.[108.1] Recent research has focused on the structure and dynamics of chromatin fibers, employing a combined TIRF and confocal FRET approach. This method utilizes three FRET labeling positions (DA1-3) to provide deeper insights into the behavior of chromatin.[108.1] These advancements in imaging techniques have transformed our understanding of chromatin structure and dynamics compared to traditional methods, allowing for a more nuanced exploration of the regulatory mechanisms that influence gene expression and cellular responses.[108.1]In this section:
Chromatin Organization
Euchromatin vs. Heterochromatin
Euchromatin and heterochromatin are two distinct structural forms of chromatin within the nucleus, each crucial for gene expression and cellular function. Euchromatin is characterized by its transcriptionally active regions, marked by a more open and accessible chromatin structure. This configuration, with wider spacing between nucleosomes and specific histone modifications, facilitates the binding of transcription machinery, promoting active gene transcription.[167.1] The open state of euchromatin allows efficient interaction with nuclear bodies involved in transcriptional regulation, essential for the expression of actively transcribed genes.[166.1] Conversely, heterochromatin consists of transcriptionally inactive DNA regions, typically located at the nuclear periphery and often associated with the nuclear lamina, contributing to gene silencing.[166.1] It is denser and more compact than euchromatin, creating barriers to transcriptional activity.[165.1] The transformation from euchromatin to heterochromatin serves as a regulatory mechanism for gene expression and replication, allowing cells to control gene expression based on their needs.[168.1] The dynamic interplay between euchromatin and heterochromatin significantly influences gene expression regulation and cellular responses to environmental changes. Euchromatin's open structure, characterized by active genes and higher accessibility to transcription machinery, facilitates active transcription.[167.1] In contrast, the conversion to heterochromatin regulates gene expression and replication. Certain genes, such as housekeeping genes, remain in a euchromatin state to ensure continuous transcription and replication.[168.1] Thus, the differential compaction of chromatin plays a crucial role in influencing transcriptional activity and overall gene expression regulation.Nucleosome Structure
Nucleosomes are fundamental units of chromatin structure, consisting of DNA wrapped around histone proteins. This organization allows approximately 5 to 6 feet of DNA to fit within the nucleus of a cell in an orderly manner, forming a structure known as chromatin through the coiling and condensing of nucleosomes.[140.1] The arrangement of nucleosomes plays a critical role in regulating gene expression by modulating the accessibility of DNA to transcription factors and other regulatory proteins.[146.1] Nucleosome positioning is influenced by various factors, including DNA sequence preferences, histone modifications, and chromatin-associated proteins, which can either favor or discourage nucleosome formation.[146.1] Specifically, nucleosomes located at gene promoters regulate the accessibility of the transcription machinery to DNA, serving as a basic layer in the complex regulation of gene expression.[147.1] Research has shown that the accessibility of DNA sequences can vary depending on whether they are located within nucleosomes or in the linker DNA between them, impacting transcription, DNA repair, and recombination processes.[148.1] Nucleosomes are dynamic structures that play a crucial role in the regulation of gene expression, extending beyond their function in DNA packaging.[137.1] The structural organization of chromatin is influenced by various mechanisms, including histone modifications, which impose significant obstacles on transcription mediated by RNA polymerase II.[138.1] Increased histone acetylation contributes to chromatin openness, creating a favorable environment for transcription by neutralizing the charge of lysine residues, thereby reducing their affinity for DNA and enhancing DNA accessibility.[140.1] In contrast, the effects of histone methylation are site-specific and are unlikely to directly affect nucleosome structure; however, they can still influence gene expression through other pathways.[141.1] Overall, understanding the interplay between these modifications and chromatin structure is essential for elucidating the dynamic regulation of gene expression during various cellular processes.[138.1] Chromatin accessibility is also regulated by the dynamic interplay of chromatin remodeling enzymes, which utilize their ability to translocate on DNA and respond to nucleosomal features to achieve various biochemical outcomes.[175.1] These remodeling processes are essential for the ordered disassembly of nucleosomes and histone exchange, which are critical for RNA polymerase II access to DNA.[157.1] Thus, the intricate structure and function of nucleosomes are vital for understanding the regulation of gene expression and the overall dynamics of chromatin organization.Chromatin Dynamics
Role in Gene Regulation
Chromatin dynamics are pivotal in gene regulation, primarily through the actions of chromatin remodeling complexes and histone modifications. ATP-dependent chromatin remodelers utilize energy from ATP hydrolysis to reposition nucleosomes, thereby influencing gene expression across various cell types. While their role in tissue stem cell fate determination is not fully understood, these remodelers are crucial for the plasticity of adult stem cells, enabling them to respond to environmental changes and acquire new cell fates.[205.1] Genome-wide mapping of epigenetic landscapes underscores the importance of chromatin remodeling in these processes, although the precise mechanisms remain under investigation.[206.1] Chromatin remodeling complexes are integral to gene regulation, as they contain protein domains that interpret chromatin targeting signals, such as histone modifications, DNA sequences, non-coding RNAs, histone variants, and DNA-bound proteins.[207.1] These complexes are essential for organizing chromatin and facilitating transcription. Histone acetylation, a well-studied post-translational modification, is associated with transcriptional activation and chromatin assembly, occurring at specific lysines in histone tails.[209.1] Hyperacetylation of histones correlates with increased transcriptional activity, highlighting the significance of histone modifications in gene expression regulation.[209.1] The interplay between chromatin remodeling and histone modifications illustrates the complexity of gene regulation and its role in cell fate determination during development.[207.1] Furthermore, the dynamic nature of chromatin allows for rapid and reversible modifications essential for DNA-templated processes like transcription, replication, and repair.[210.1] Modulating chromatin structure through post-translational modifications and histone variants contributes to the spatiotemporal organization necessary for effective genomic activities in eukaryotic cells.[220.1]Epigenetic Modifications
Epigenetic modifications play a crucial role in the regulation of gene expression and chromatin dynamics in eukaryotic cells. In eukaryotes, DNA is highly compacted within the nucleus into a structure known as chromatin, and the modulation of this chromatin structure allows for precise regulation of gene expression, which in turn controls cell fate decisions.[184.1] Chromatin dynamics are regulated by chromatin modification enzymes, including chromatin remodeling complexes and histone post-translational modifications.[180.1] Dysregulation of chromatin dynamics and aberrant histone modifications have been linked to the occurrence of various diseases, including cancer.[180.1] One of the primary mechanisms of epigenetic regulation involves histone modifications, such as methylation and acetylation. For instance, H3 lysine 4 (H3K4) methylation is strongly associated with active gene expression and has been extensively studied in the context of cancer development.[187.1] Conversely, histone modifications like H3K27 trimethylation, deposited by the PRC2 complex, are linked to gene repression and play essential roles in developmental gene regulation.[193.1] These modifications form a regulatory code that dictates gene expression in different cellular contexts, with specific histone variants also influencing nucleosome stability and positioning.[191.1] In cancer, aberrant histone modifications can lead to dysregulation of gene expression, contributing to tumorigenesis. For example, the oxidation of H3.1Cys96 has been shown to promote resistance to chemotherapy in breast cancer, highlighting the potential for targeting specific histone modifications as a therapeutic strategy.[186.1] Additionally, histone deacetylase inhibitors (HDACi) represent a novel class of targeted therapies that manipulate the immune response to cancer through epigenetic modification.[188.1] The dynamic nature of chromatin is significantly influenced by histone modifications, particularly histone methylation, which plays a crucial role in gene silencing and chromatin regulation. This post-translational modification occurs on lysine and arginine residues of histone proteins, thereby influencing gene expression and chromatin structure.[189.1] Specific histone modifications, such as methylation of histone H3 lysine 9, create binding sites for HP1 proteins, while histone H3 lysine 4 methylation can disrupt the binding of nucleosome remodeling and deacetylase (NuRD) repressor complexes.[192.1] Understanding these mechanisms is essential, as establishing a cell-type-specific chromatin pattern predestines future cell differentiation and deters cell-lineage infidelity, which is particularly relevant during neoplastic transformation.[195.1] Consequently, the dynamics and mechanisms underlying chromatin remodeling have become a major focus of recent molecular genetic research, highlighting their importance in cellular differentiation and the maintenance of cellular identity.[195.1]Techniques For Chromatin Analysis
Microscopy Methods
Microscopy methods have become essential for analyzing chromatin structure and understanding its role in gene expression. One significant technique is Chromatin Conformation Capture (3C), which provides insights into the three-dimensional organization of chromatin within living cells, thereby elucidating the spatial relationships that influence transcriptional regulation and other genomic processes.[259.1] Advancements in microscopy, particularly those utilizing next-generation sequencing (NGS), have further enhanced our ability to analyze chromatin structure on a genome-wide scale. These methods have revealed the critical functions of chromatin architecture in maintaining and regulating genomic information.[260.1] Imaging-based techniques, such as DNA fluorescence in situ hybridization (FISH), utilize sequence-specific probes to capture the spatial arrangement of chromatin loci, offering high-resolution insights at the single-cell level.[261.1] Emerging single-molecule techniques have significantly advanced our understanding of chromatin dynamics and the interactions between chromatin and regulatory proteins. Techniques such as magnetic tweezers, optical tweezers, single-molecule Förster resonance energy transfer (smFRET) measurements, and atomic force microscopy (AFM) imaging have been instrumental in studying nucleosome dynamics and the modulation of regulatory protein binding by dynamic histone tails.[246.1] These single-molecule approaches provide sufficient resolution to avoid population-averaging effects, allowing for a more nuanced understanding of chromatin structure and its implications for gene expression.[248.1] Imaging-based methods, including DNA fluorescence in situ hybridization (FISH), utilize sequence-specific probes to capture the spatial arrangement of chromatin loci within the nucleus, offering high-resolution insights at the single-cell level.[261.1] Furthermore, techniques such as single-cell Hi-C and scSPRITE highlight significant cell-to-cell heterogeneity in genome organization, emphasizing the necessity for methods that can simultaneously probe chromatin structure, RNA, and proteins within individual cells.[261.1] The integration of these techniques reveals significant similarities in chromatin structure at the population level, thereby elucidating the complex interactions that are essential for gene expression.[261.1]Sequencing-Based Approaches
Sequencing-based approaches have become integral to the field of chromatin analysis, with Chromatin Immunoprecipitation (ChIP) serving as a foundational technique. ChIP is recognized as the tried and true workhorse of chromatin analysis, and while new and improved variations of this method continue to emerge, the fundamental principles of ChIP remain central to all chromatin analyses.[229.1] For those interested in exploring additional methodologies related to chromatin structure, such as chromosome conformation capture methods, resources like the article on Hi-C and related techniques are available for further reading.[229.1] Another important sequencing-based method is the combination of high-throughput sequencing with Chromosome Conformation Capture (3C) techniques. This integration has enabled the exploration of the three-dimensional organization of the genome, revealing how distant genomic regions interact within the nuclear space. Such methods, including Hi-C, provide crucial data on the spatial arrangement of chromatin, which is essential for understanding gene regulation and chromatin architecture.[236.1] Additionally, advancements in sequencing technologies have facilitated the analysis of DNA methylation patterns and the identification of three-dimensional chromatin interactions. These developments have expanded the toolkit available for chromatin biology, allowing for a more comprehensive understanding of the complex regulatory networks that govern gene expression.[226.1] Recent studies utilizing these sequencing-based approaches have uncovered significant findings regarding the dynamic nature of chromatin. For instance, the investigation of enhancer-gene regulation networks through H3K27ac HiChIP has revealed how chromatin structures change in response to cellular processes, such as ferroptosis in glioblastoma cells.[250.1] Furthermore, the development of CRISPR-ChIP has enabled researchers to dissect the factors involved in chromatin regulation, providing deeper insights into the functional partitioning of histone modifications.[251.1]In this section:
Chromatin In Cell Division
Mitosis and Meiosis
Mitosis and meiosis are two distinct processes of cell division that play crucial roles in the life cycle of eukaryotic organisms. Mitosis is responsible for the division of body cells, resulting in two genetically identical diploid daughter cells, while meiosis involves the division of sex cells, yielding four genetically diverse haploid daughter cells through two rounds of division.[276.1] During both processes, chromatin, which is the packaging of DNA around histone proteins, undergoes significant changes. In interphase, chromatin is mostly decondensed, making individual chromosomes invisible. However, during prophase of mitosis, chromatin condenses into visible chromosomes, and the centrosomes organize the mitotic spindle to facilitate the separation of sister chromatids.[271.1] In mitosis, sister chromatids separate during metaphase and anaphase, ensuring that each daughter cell receives an identical set of chromosomes.[275.1] In contrast, meiosis introduces genetic variation through processes such as crossing over, which occurs in meiosis I, leading to daughter cells that are not identical to the parent cell.[275.1] Thus, while both mitosis and meiosis are essential for cell division, they serve different functions and result in distinct outcomes for the daughter cells produced. Meiosis is a specialized form of cell division that differs from mitosis in several key aspects. The most significant distinction is that meiotic cells undergo two sequential divisions, known as meiosis I and meiosis II, without an intervening S phase.[268.1] During meiosis I, chromatin undergoes major reorganization, which includes chromosome condensation, the establishment of meiotic chromosome structure, and the pairing of homologous chromosomes.[269.1] This pairing is essential for genetic diversity, as it facilitates crossing over, a process that occurs during prophase I, resulting in daughter cells that are not genetically identical to the parent cells.[275.1] Furthermore, meiotic chromosome condensation occurs simultaneously with the alignment of homologous chromosomes and the formation of programmed double-strand breaks, which are crucial for homologous recombination.[269.1] These differences in chromatin behavior and organization between mitosis and meiosis underscore the unique mechanisms that contribute to the generation of genetically diverse haploid cells in meiosis.[275.1] Mitosis and meiosis are two distinct processes of cell division in eukaryotic cells, each serving different functions and resulting in different outcomes. Mitosis involves the division of body cells and results in two daughter cells that are genetically identical (diploid) to the parent cell, as it ensures that sister chromatids separate during the process.[275.1] In contrast, meiosis is responsible for the division of sex cells and includes two rounds of division, ultimately producing four genetically distinct haploid daughter cells.[275.1] This genetic variability arises from processes such as crossing over during meiosis I, which ensures that the chromosomes that segregate into daughter cells are not identical to those of the parent cell.[275.1] Thus, while mitosis maintains genetic stability by producing identical cells, meiosis contributes to genetic diversity, which is essential for evolution and adaptation in sexually reproducing organisms.[275.1]References
[2] Chromatin - Wikipedia — The major structures in DNA compaction: DNA, the nucleosome, the 11 nm beads on a string chromatin fibre and the metaphase chromosome. Chromatin is a complex of DNA and protein found in eukaryotic cells. The primary function is to package long DNA molecules into more compact, denser structures. Through altering the chromatin structure, histones residues are adding chemical groups namely phosphate, acetyl and one or more methyl groups and these control the expressions of gene building by proteins to acquire DNA. Moreover, resynthesis of the delighted zone, DNA will be repaired by processing and restructuring the damaged bases. Histone H4-K16 acetylation controls chromatin structure and protein interactions.
[4] Chromatin - Definition, Composition, Functions, Examples and FAQs — Chromatin Function. At first, chromatin was thought to be the component that gave the cell nucleus its color. Later, it was discovered that it is one of the most significant DNA expression controllers and is not merely a coloring agent. The structure of chromosomes is crucial for DNA replication. DNA is packaged in chromatin and nucleosomes
[7] Chromatin - National Human Genome Research Institute — Chromatin. The total DNA in the cell is about 5 to 6 feet long which has to fit inside the nucleus of a cell in an orderly fashion. DNA molecules first wrap around the histone proteins forming beads on string structure called nucleosomes. Nucleosomes further coil and condense/gather to form fibrous material which is called chromatin.
[8] Regulation of chromatin by histone modifications - PMC — Histone tail clipping, which results in the loss of the first 21 amino acids of H3 will have similar effects. In contrast, neutral modifications such as histone methylation are unlikely to directly perturb chromatin structure since these modifications are small and do not alter the charge of histones. Regulating the binding of chromatin factors
[9] The Role of Chromatin during Transcription - Cell Press — Chromatin structure imposes significant obstacles on all aspects of transcription that are mediated by RNA polymerase II. The dynamics of chromatin structure are tightly regulated through multiple mechanisms including histone modification, chromatin remodeling, histone variant incorporation, and histone eviction. In this Review, we highlight advances in our understanding of chromatin
[10] How histone modifications impact gene regulation | biomodal — Moreover, chemical modifications to histone tails can significantly impact gene expression. DNA replication: Histones are also important in the process of DNA replication. The expression of histone genes is tightly regulated and coupled with DNA replication to ensure proper packaging of newly synthesised DNA into chromosomes.
[17] Chromatin structure and organization: the relation with gene expression ... — These successive folding levels rely on the formation of chromatin loops ranging from few kb to some Mb. In addition to a packaging and structural role, the high-order organization of genomes functionally impacts on gene expression program. This review summarises to which extent each level of chromatin compaction does affect gene regulation.
[18] Role of chromatin in gene expression and Gene silencing — Chromatin also regulates the expression of the gene in a cell, as compaction of chromatin limits gene accessibility for transcription factors. There are two types of chromatin i.e.1)Heterochromatin - chromatin is tightly packed and not actively transcribed. 2)Euchromatin - chromatin is loosely packed and accessible for transcription.
[19] Chromatin structure and gene expression - PubMed — Another problem raised by chromatin structure concerns the establishment of boundaries between active and inactive chromatin domains. We have identified a DNA element at the 5' end of the chicken beta-globin locus, near such a boundary, that has the properties of an insulator; in test constructions, it blocks the action of an enhancer on a
[20] Chromatin Mechanisms Regulating Gene Expression In Health And Disease ... — In the first instance, the regulatory machinery gains entry to the ~1% of the genome that comprises the regulatory elements active in any one cell type by creating highly accessible nucleosome-free regions that exist as DHSs.13 In most cases this involves the cooperative action of different transcription factors, but in some cases the creation of these DHSs is initiated by specialized pioneer factors that have the intrinsic ability to bind to chromatin compacted by histone H1.59 Other specific factors, such as the transcription factors NFAT and NF-κB, are intimately associated with the induction of DHSs within promoter and enhancer elements in response to activation by immune and pro-inflammatory stimuli.60,61 NFAT is a key mediator of T-cell receptor (TCR) signaling, whereas NF-κB is a key mediator of pro-inflammatory signals such as bacterial lipopolysaccharide (LPS).
[27] The molecular basis of heterochromatin assembly and epigenetic ... — Heterochromatin plays a fundamental role in gene regulation, genome integrity, and silencing of repetitive DNA elements. Histone modifications are essential for the establishment of heterochromatin domains, which is initiated by the recruitment of histone-modifying enzymes to nucleation sites.
[28] Heterochromatin and Epigenetic Control of Gene Expression | Science - AAAS — In addition to its role in the maintenance of genome stability, heterochromatin plays a central role in the regulation of gene expression during development and cellular differentiation. Heterochromatin-like structures are involved in the stable inactivation of developmental regulators such as the homeotic gene clusters in Drosophila and
[29] New insights into the regulation of heterochromatin - PMC — Yet the role of heterochromatin changes during aging is unclear. It is possible that loss of heterochromatin results in the misregulation of gene expression, which contributes to the aging-associated phenotypes . Alternatively, heterochromatin loss might affect other essential functions of heterochromatic domains, such as telomeres .
[30] Heterochromatin: Structure, Function, and Role in Genetics — Heterochromatin is a form of chromatin that is very densely packed and transcriptionally inactive. While DNA in euchromatin regions is loosely packed and accessible to the transcription machinery, allowing active gene expression, Heterochromatin keeps the underlying DNA inaccessible and silenced.. This heterochromatic state plays essential roles in regulating gene expression, maintaining
[31] Euchromatin vs. Heterochromatin - What's the Difference? | This vs. That — Euchromatin vs. Heterochromatin What's the Difference? Euchromatin and heterochromatin are two distinct forms of chromatin, which is the complex of DNA and proteins that make up chromosomes. Euchromatin is characterized by its loose and open structure, allowing for active gene expression and transcription.
[32] Heterochromatin vs Euchromatin: Differences and Development Roles — The interplay between heterochromatin and euchromatin is crucial for gene expression and guiding cellular development and differentiation. During development, cells undergo a series of regulated changes, transitioning from pluripotent stem cells to various specialized cell types.
[52] A Condensed History of Chromatin Research | SpringerLink — The history of chromatin research provides numerous lessons for research. One of them is the necessity to put forward theories, even if they prove later wrong. Another lesson is obviously the need to put forward the development of new technologies. Though paradoxically, often, new technical insights come from new questions.
[54] Chromatin: Its history, current research, and the seminal researchers ... — Chromatin: Its history, current research, and the seminal researchers and their philosophy - PubMed Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation Search: Search Your saved search Name of saved search: Add to Search Chromatin: Its history, current research, and the seminal researchers and their philosophy Chromatin: Its history, current research, and the seminal researchers and their philosophy Add to Search The concept of chromatin as a complex of nucleic acid and proteins in the cell nucleus was developed by cytologists and biochemists in the late 19th century. Since the late 20th century, research on chromatin modifications has also been conducted under the label of epigenetics. Add to Search Add to Search Add to Search Add to Search
[55] (PDF) Chromatin: Its history, current research, and the seminal ... — Chromatin research largely precedes postgenomics but has currently found a true rebirth through epigenetics (Deichmann 2015). Given that DNA is structurally and topologically constrained by
[67] Before Watson and Crick in 1953 Came Friedrich Miescher in 1869 — The story of genetics typically omits the original discovery of the molecular nature of DNA: Friedrich Miescher's 1869 discovery of the substance he christened “nuclein”. This turn in the historical memory of Miescher highlights a discontinuity in the theoretical understanding of nuclein’s role in heredity, brought about by the working out of the genetic code, while concealing a continuity of methods (Levene and Bass 1931). Yet, with the help of Friedrich Miescher and the reception of his discovery, we can better comprehend how the history of genetics consists of two strands: DNA and chromatin; information and physiology, intertwined, twisting around each other, from 1869 until the present. Friedrich Miescher’s discovery in the historiography of genetics: from contamination to confusion, from nuclein to DNA.
[68] From discovering to understanding: Friedrich Miescher's attempts to ... — Between 1868 and 1869, Miescher worked at the University of Tübingen in Germany (Figs 2,3), where he tried to understand the chemical basis of life.A crucial difference in his approach compared with earlier attempts was that he worked with isolated cells—leukocytes that he obtained from pus—and later purified nuclei, rather than whole organs or tissues.
[74] How Is Chromatin Labeled for Advanced Research? — These techniques are essential for understanding gene regulation and nuclear architecture. Chemical And Genetic Tools. Labeling chromatin requires precise tools targeting DNA, histones, or associated proteins. Chemical and genetic approaches offer versatile methods for visualizing chromatin structure and dynamics in both fixed and live-cell
[75] Advanced microscopy methods for visualizing chromatin structure ... — Light microscopy is an enabling technology for biology. It allows non-invasive visualization of cellular and sub-cellular structures in multiple colors, in 3D and in living cells. The use of fluorescent probes such as fluorescent proteins ensures high contrast and high molecular specificity.
[76] Advances in chromatin and chromosome research: perspectives from ... — In conclusion, chromatin and single nucleosome live-cell imaging will continue to contribute to change the view of chromatin from fixed and static to irregular and dynamic nature (e.g. liquid droplets of chromatin (Gibson et al., 2019; Maeshima et al., 2010). From a functional viewpoint, phase separation as a mechanism to organize chromatin and chromatin-based transactions provides a number of benefits (reviewed in (Alberti et al., 2019; Banani et al., 2017; Hyman et al., 2014)): (1) Phase separation is a self-organizing process that does not require energy consumption, (2) The weak but multivalent interactions involved are easier to modulate than protein-protein interactions, (3) Small changes in environmental conditions such as pH or temperature can elicit a strong response in systems near phase boundaries, (5) The formation of distinct types of immiscible condensates offers a mechanism to sequester molecules at high concentrations, (6) Partitioning of chromatin and macromolecules into condensates based on reversible marks (post-translational modifications, TF binding, etc.) can confer specificity in the crowded nuclear environment.
[77] Genes Under the Microscope: Insights into Chromosome Structure — Advancements in microscopy have transformed the study of chromosome structure, enabling researchers to examine genetic material with unprecedented clarity. Traditional light microscopy, while foundational in early cytogenetics, lacked the resolution to reveal DNA's intricate organization within the nucleus.
[96] C David Allis Impact on Histone and Chromatin Advancements — New research is uncovering deeper levels of complexity in gene regulation. One promising area involves phase separation in chromatin organization. Recent studies suggest that certain histone modifications and chromatin-associated proteins contribute to the formation of biomolecular condensates—membrane-less compartments that concentrate
[97] Advances in chromatin and chromosome research: perspectives from ... — In conclusion, chromatin and single nucleosome live-cell imaging will continue to contribute to change the view of chromatin from fixed and static to irregular and dynamic nature (e.g. liquid droplets of chromatin (Gibson et al., 2019; Maeshima et al., 2010). From a functional viewpoint, phase separation as a mechanism to organize chromatin and chromatin-based transactions provides a number of benefits (reviewed in (Alberti et al., 2019; Banani et al., 2017; Hyman et al., 2014)): (1) Phase separation is a self-organizing process that does not require energy consumption, (2) The weak but multivalent interactions involved are easier to modulate than protein-protein interactions, (3) Small changes in environmental conditions such as pH or temperature can elicit a strong response in systems near phase boundaries, (5) The formation of distinct types of immiscible condensates offers a mechanism to sequester molecules at high concentrations, (6) Partitioning of chromatin and macromolecules into condensates based on reversible marks (post-translational modifications, TF binding, etc.) can confer specificity in the crowded nuclear environment.
[105] Unveiling structural and dynamical features of chromatin using NMR ... — This review summarizes recent advances in NMR studies of chromatin structure and dynamics. It highlighted that NMR revealed unique molecular characteristics for nucleosomes that are often invisible experimentally by other techniques like cryogenic electron microscopy (cryo-EM) and X-ray diffraction (XRD).
[106] Structural and dynamic studies of chromatin by solid-state NMR ... — Structural and dynamic studies of chromatin by solid-state NMR spectroscopy - PubMed Search: Search Your saved search Name of saved search: Structural and dynamic studies of chromatin by solid-state NMR spectroscopy Structural and dynamic studies of chromatin by solid-state NMR spectroscopy In this review we highlight recent applications of magic angle spinning solid-state NMR - an emerging technique that is uniquely-suited toward providing atomistic information for rigid and flexible regions within biomacromolecular assemblies - to detailed characterization of structure, conformational dynamics and interactions for histone core and tail domains in condensed nucleosomes and oligonucleosome arrays mimicking chromatin at high densities characteristic of the cellular environment. Histone H3 core domain in chromatin with different DNA linker lengths studied by 1H-Detected solid-state NMR spectroscopy.
[108] FRET-based dynamic structural biology: Challenges, perspectives and an ... — Understanding how biomolecules couple structural dynamics with function is at the heart of several disciplines and remains an outstanding goal in biology. ... Study of structure and dynamics of chromatin fibers. A combined TIRF and confocal FRET study of structure and dynamics of chromatin fibers using three FRET labeling positions (DA1-3) for
[109] Structural and dynamic studies of chromatin by solid-state NMR ... — Chromatin is a complex of DNA with histone proteins organized into nucleosomes that regulates genome accessibility and controls transcription, replication and repair by dynamically switching between open and compact states as a function of different parameters including histone post-translational modifications and interactions with chromatin modulators.
[137] Chromatin Organization and Transcriptional Regulation - PMC — Chromatin organization in the mammalian nucleus. (A) Chromosomes are organized in chromosome territories.(B) Chromosome territories are comprised of fractal globules, and fractal globules from adjacent chromosome territories can interdigitate.(C) Chromatin fibers interact (i) within a fractal globule (frequent), (ii) between fractal globules of the same chromosome territory (rare), or between
[138] Chromatin Organization - Advanced Cell Biology - Study Toolkit — Chromatin. As we just reviewed, a nucleosome is the fundamental repeating unit of chromatin. Chromatin is the overall DNA structure in the cell nucleus and can exist in different states of compaction and organization. These differing states can be related to different gene expression levels and cellular requirements.
[140] Chromatin - National Human Genome Research Institute — Chromatin. The total DNA in the cell is about 5 to 6 feet long which has to fit inside the nucleus of a cell in an orderly fashion. DNA molecules first wrap around the histone proteins forming beads on string structure called nucleosomes. Nucleosomes further coil and condense/gather to form fibrous material which is called chromatin.
[141] Spatial organization of genes as a component of regulated expression — We should therefore look at territories as pliable, rather than rigid or impenetrable structures, especially in light of data that transcriptional machinery is shown to have the ability to access the interior of chromosome territories (Mahy et al. 2002b). In fact, most transcriptional factors are quite capable of accessing the interiors of
[146] Nucleosome Sliding: Mechanisms That Reshape Gene Access — This arrangement condenses the genome while also controlling gene expression by modulating DNA accessibility to transcription factors and other regulatory proteins. Nucleosome positioning is influenced by DNA sequence preferences, histone modifications, and chromatin-associated proteins. Specific DNA motifs favor or discourage nucleosome
[147] Nucleosome mobility and the regulation of gene expression: Insights ... — Nucleosomes at the promoters of genes regulate the accessibility of the transcription machinery to DNA, and function as a basic layer in the complex regulation of gene expression. ... ‐molecule results are also consistent with previous gel‐based reports of increased sliding by H2A.Z containing nucleosome on DNA positioning sequences.42.
[148] Nucleosome positioning: how is it established, and why does it matter ... — Decades of single gene studies have confirmed the intuitive notion that depending on whether they are found in the nucleosome or in the linker DNA between nucleosomes, DNA sequences can be more or less accessible to transcription, DNA repair or DNA recombination machinery (Boeger et al., 2008; Durrin et al., 1992; Green and Almouzni, 2002
[157] Histone exchange, chromatin structure and the regulation of ... — Access of RNA polymerase II to DNA is regulated by the ordered disassembly of nucleosomes and by histone exchange. Chromatin modifications, chromatin remodellers, histone chaperones and histone
[165] Difference Between Euchromatin and Heterochromatin — Difference Between Euchromatin and Heterochromatin | Characteristics, Structure, Function Difference Between Euchromatin and Heterochromatin Main Difference – Euchromatin vs Heterochromatin Euchromatin and heterochromatin are the two structural forms of DNA in the genome, which are found in the nucleus. The main difference between euchromatin and heterochromatin is that euchromatin consists of transcriptionally active regions of DNA whereas heterochromatin consists of transcriptionally inactive DNA regions in the genome. 3. What is the difference between Euchromatin and Heterochromatin Difference Between Euchromatin and Heterochromatin Euchromatin and heterochromatin are two types of DNA structure found within the nucleus. Euchromatin with less DNA density is stained lightly and heterochromatin with high DNA density is stained darkly. Therefore, the main difference between euchromatin and heterochromatin lies in both their structure and function.
[166] Heterochromatin vs Euchromatin: Differences and Development Roles — Heterochromatin is typically found at the nuclear periphery, often associated with the nuclear lamina, which may play a role in gene silencing. Euchromatin is generally located towards the interior of the nucleus, where it can interact with various nuclear bodies involved in transcriptional regulation. Gene Expression Regulation
[167] Molecular Complexes at Euchromatin, Heterochromatin and Centromeric ... — 2. Euchromatin. Euchromatin is characterized by active genes, wider spacing between nucleosomes, higher accessibility to transcription machinery, histone modifications and variants that facilitate active transcription .The more open, unfolded structure of euchromatin allows transcriptional machinery to bind to the DNA, thereby facilitating its transcription.
[168] Heterochromatin vs. Euchromatin: 16 Differences, Examples - Microbe Notes — The transformation of euchromatin to heterochromatin acts as a method for regulating gene expression and replication. For this purpose, some genes like housekeeping genes are always arranged in euchromatin conformation as they have to be continuously replicated and transcribed.
[175] Mechanisms and Functions of ATP-Dependent Chromatin-Remodeling Enzymes ... — For example, the lobes of the Sulpholobus Snf2 homolog SSO1653 are flipped 180° with respect to the closed conformation (Dürr et al., 2005). ... Chromatin-remodeling enzymes appear to use the ability to translocate on DNA and the ability to respond to nucleosomal features to achieve a diverse range of biochemical outputs. These diverse
[180] Chromatin Dynamics: Chromatin Remodeler, Epigenetic Modification and ... — Chromatin dynamic is regulated by chromatin modification enzymes including chromatin remodeling complex and histone posttranslational modifications. Multiple studies have shown that chromatin dynamics dysregulation and aberrant and histone modifications resulted in the occurrence of various diseases and cancers.
[184] Chromatin regulation and dynamics in stem cells - PMC — In eukaryotes, DNA is highly compacted within the nucleus into a structure known as chromatin. Modulation of chromatin structure allows for precise regulation of gene expression, and thereby controls cell fate decisions. Specific chromatin
[186] Histone H3.1 is a chromatin-embedded redox sensor ... - Cell Press — Palma et al. report that H3.1Cys96 oxidation is a functional posttranslational modification involved in the regulation of gene expression. In breast cancer, H3.1Cys96 oxidation promotes resistance to first-line chemotherapeutic drugs and stimulates metastasis. They also show that suppressing H3.1Cys96 oxidation inhibits metastasis while resensitizing cancer cells to chemotherapy.
[187] The role of histone post-translational modifications in cancer and ... — H3 lysine 4 (H3K4) methylation is among the most extensively studied histone modifications due to its strong association with gene expression and cancer development. As a result, HDACs have emerged as significant therapeutic targets in cancer, with their inhibition leading to increased histone acetylation and potential restoration of normal gene expression patterns in tumor cells. Abnormal histone ubiquitination can drive tumorigenesis by altering the expression of tumor suppressors and oncogenes, misregulating cell differentiation, and promoting the proliferation of cancer cells. Among the existing small-molecule histone acetyltransferase (HAT) inhibitors, many studies have focused on compounds that target p300/CBP, which play key roles in acetylating histone H3 at lysines 18 and 27 (H3K18, H3K27) to facilitate gene activation critical for cell growth and differentiation (230). Regulation of c-Myc expression by the histone demethylase JMJD1A is essential for prostate cancer cell growth and survival.
[188] Histone modifications in epigenetic regulation of cancer: Perspectives ... — Histone modifications in epigenetic regulation of cancer: Perspectives and achieved progress - ScienceDirect Gene expression changed by cancer in the epigenetic pathways is very complex and is determined by changes in chromatin structure including DNA methylation, post-translational histone modifications, nucleosome remodeling, and small non-encoding RNAs . One such approach is to use histone deacetylase inhibitors (HDACi), a novel class of targeted therapies, which manipulate the immune response to cancer through epigenetic modification. Aberrant epigenetic modifications, including DNA methylation, histone modification, and non-coding RNA (ncRNA)-mediated gene regulation play a crucial role in cancer progression. DNA methylation, histone acetylation and methylation of epigenetic modifications as a therapeutic approach for cancers
[189] How histone modifications impact gene regulation | biomodal — How histone modifications impact gene regulation | biomodal Histone methylation plays a crucial role in gene silencing and chromatin regulation. This post-translational modification occurs on lysine and arginine residues of histone proteins, influencing gene expression and chromatin structure. Understanding these mechanisms of histone methylation and heterochromatin formation is crucial for unravelling the complexities of gene regulation and epigenetic inheritance. Phosphorylation of histones, such as H3S10 and H3 serine 28 (H3S28), can modulate chromatin structure and influence the binding of transcription factors and chromatin-remodelling complexes, thereby regulating gene expression. Histone modifications play a crucial role in regulating gene expression and chromatin structure. To wrap up, histone modifications play a crucial role in regulating gene expression and chromatin structure.
[191] What Is the Purpose of Histones in DNA and Gene Regulation? — These modifications form a regulatory code dictating gene expression in different cellular contexts. Histone variants also influence gene regulation by altering nucleosome stability and positioning. The incorporation of H3.3 into active chromatin regions reinforces transcriptional activity, while macroH2A in silenced domains reinforces repression.
[192] Regulation of chromatin by histone modifications | Cell Research - Nature — Regulation of chromatin by histone modifications | Cell Research Reevaluating the roles of histone-modifying enzymes and their associated chromatin modifications in transcriptional regulation Conversely, DNA methylation can inhibit protein binding to specific histone modifications. Regulation of chromatin structure by site-specific histone H3 methyltransferases. Proline isomerization of histone H3 regulates lysine methylation and gene expression. Histone H4-K16 acetylation controls chromatin structure and protein interactions. Regulation of HP1-chromatin binding by histone H3 methylation and phosphorylation. ING2 PHD domain links histone H3 lysine 4 methylation to active gene repression. Methylation of histone H3 lysine 9 creates a binding site for HP1 proteins. Histone H3 lysine 4 methylation disrupts binding of nucleosome remodeling and deacetylase (NuRD) repressor complex.
[193] Chromatin modifiers: regulators of cellular differentiation — Chromatin dynamics during differentiation. ... Chromatin regulators involved in gene regulation during postimplantation development and cellular differentiation. Open in a new tab (A) PcG proteins play important roles in repressing developmental genes. The PRC2 complex deposits the repressive H3K27me3 marks, which create binding sites for the
[195] Chromatin remodeling in development and differentiation — Establishing a cell-type-specific chromatin pattern thus predestines future cell differentiation and deters cell-lineage infidelity, as it often occurs during neoplastic transformation. As such, understanding the dynamics and mechanisms underlying chromatin remodeling has been a major focus of recent molecular genetic research that holds great
[205] Chromatin remodeling in tissue stem cell fate determination — Meanwhile, ATP-dependent chromatin remodelers use the energy from ATP hydrolysis to remodel nucleosomes, thereby affecting chromatin dynamics and the regulation of gene expression programs in each cell type. However, the role of chromatin remodelers in tissue stem cell fate determination is less well understood.
[206] The Yin and Yang of Chromatin Dynamics In Stem Cell Fate Selection — However, stem cells also provide host tissues with a remarkable plasticity to respond to perturbations. How adult stem cells choose and acquire new fates is unknown, but the genome-wide mapping of epigenetic landscapes suggests a critical role for chromatin remodeling in these processes.
[207] Chromatin Remodelers: From Function to Dysfunction - PMC — To achieve this, chromatin remodeling complexes harbor protein domains that specifically read chromatin targeting signals, such as histone modifications, DNA sequence/structure, non-coding RNAs, histone variants or DNA bound interacting proteins. 80.Moshkin Y.M., Chalkley G.E., Kan T.W., Reddy B.A., Ozgur Z., van Ijcken W.F.J., Dekkers D.H.W., Demmers J.A., Travers A.A., Verrijzer C.P. Remodelers organize cellular chromatin by counteracting intrinsic histone-DNA sequence preferences in a class-specific manner. 83.Poot R.A., Dellaire G., Hlsmann B.B., Grimaldi M.A., Corona D.F.V., Becker P.B. HuCHRAC, a human ISWI chromatin remodelling complex contains hACF1 and two novel histone-fold proteins. 97.Duan M.-R., Smerdon M.J. Histone H3 lysine 14 (H3K14) acetylation facilitates DNA repair in a positioned nucleosome by stabilizing the binding of the chromatin Remodeler RSC (Remodels Structure of Chromatin) J.
[209] Chromatin Remodeling and the Control of Gene Expression — Since the early discovery of histone acetylation by Allfrey and colleagues (), this post-translation modification has been correlated with the processes of transcription and chromatin assembly.Acetylation occurs at specific lysines in the flexible N-terminal histone tails that protrude from the nucleosome surface (11, 14).Hyperacetylation of histones is associated with transcriptional activity
[210] Chromatin-remodeling links metabolic signaling to gene expression — An ideal mechanism to achieve dynamic gene expression is through modification of chromatin because they are rapid, responsive, and reversible. Chromatin is a complex structure that is dynamically reorganized to facilitate DNA-templated processes such as transcription, chromosome segregation, DNA replication, and DNA repair.
[220] Recent Advances in Investigating Functional Dynamics of Chromatin — The accomplishment of genomic DNA activities in eukaryotic cells is propagated from the modulation of dynamic spatiotemporal organization of chromatin, which is achieved through factors including post-translational modifications (PTMs) (Jenuwein and Allis, 2001; Bannister and Kouzarides, 2011; Bowman and Poirier, 2014; Fenley et al., 2018), incorporation histone variants (Talbert and Henikoff, 2016; Martire and Banaszynski, 2020), remodelers, and other effector proteins (Tyagi et al., 2016; Armeev et al., 2019; Reyes et al., 2021). Recent advances in SSNMR studies of chromatin allows elucidating the structure and dynamics for both the highly flexible tails and the rigid core for samples in compact states, where the water contents of the nucleosome samples are around 50–90% (Gao et al., 2013; Shi et al., 2018; Xiang et al., 2018; Ackermann and Debelouchina, 2021; Zandian et al., 2021).
[226] Chromatin: Methods and Protocols - SpringerLink — This volume provides cutting-edge techniques to further the study chromatin biology. Chapters include both novel and well-established methods for the analysis of DNA-associated proteins, DNA methylation, three-dimensional chromatin interactions, deep sequencing-based tools, and data analysis pipelines.
[229] Chromatin Analysis - EpiGenie — ChIP is the tried and true workhorse of chromatin analysis; new and improved variations arise, but the basic idea of ChIP is at the heart of all chromatin analyses. For additional reading about chromosome conformation capture methods, check out this article on Hi-C and related methods from our friends at Active Motif.
[236] Metagenome Analysis Exploiting High-Throughput Chromosome Conformation ... — However, an important step was recently reached by combining high-throughput sequencing with the chromosome conformation capture (3C) technique , giving access to the multiscale 3D organization of the DNA sequence. 3C and its genomic derivatives have in recent years become popular tools to study spatial chromosome organization.
[246] Dynamics of nucleosomes and chromatin fibers revealed by single ... — The single-molecule techniques that have been used to study nucleosome dynamics are shown in schematic, which techniques include magnetic tweezers, optical tweezers, smFRET measurements, and AFM imaging. ... Binding of regulatory proteins to nucleosomes is modulated by dynamic histone tails. Nat Commun. 2021;12:5280. doi: 10.1038/s41467-021
[248] Single-Molecule Techniques to Study Chromatin - PMC - PubMed Central (PMC) — Single-Molecule Techniques to Study Chromatin. ... scanning required single-molecule approaches to provide sufficient resolution and to avoid population-averaging effects. Single-molecule ... Liu Z., Thurman A. L., Powers L. S., Zou M., et al. (2019). Single-molecule long-read sequencing reveals the chromatin basis of gene expression.
[250] Three-Dimensional Gene Regulation Network in Glioblastoma Ferroptosis — In this study, H3K27ac HiChIP was performed to investigate the change of active enhancer-related 3D chromatin structures in glioblastoma cell ferroptosis. By combining an analysis of RNA-seq and ChIP-seq data, this study found a 3D enhancer-gene regulation network in glioblastoma cell ferroptosis.
[251] CRISPR-ChIP reveals selective regulation of H3K79me2 by ... - Nature — Here the authors develop CRISPR-ChIP to enable the identification of factors required for chromatin regulation. Using this new method, they unveil a functional partitioning of H3K79 methylation
[259] Chromatin Conformation Analysis (3C) Techniques - EpiGenie — Chromatin Conformation Capture (3C) is an important technique used to study chromatin structure, as well as the basis for several other derivative techniques. 3C provides information on 3D chromatin structures that occur in living cells.
[260] Methods for Genome-Wide Chromatin Interaction Analysis — Recent analyses revealed the essential function of chromatin structure in maintaining and regulating genomic information. Advancements in microscopy, nuclear structure observation techniques, and the development of methods utilizing next-generation sequencers (NGSs) have significantly progressed these discoveries. Methods utilizing NGS enable genome-wide analysis, which is challenging with
[261] Advances in the multimodal analysis of the 3D chromatin structure and ... — Alternatively, imaging-based methods, including DNA fluorescence in situ hybridization (FISH), utilize sequence-specific probes to capture the spatial arrangement of chromatin loci within the nucleus, offering high-resolution insights at the single-cell level. However, emerging evidence from using various single-cell techniques (e.g., scHi-C, scSPRITE, and imaging approaches) highlights a significant cell-to-cell heterogeneity in genome organization, underscoring the need for methods that can simultaneously probe the chromatin structure, RNA, and proteins within the same single cells57,58,59,60,61,62. This approach correlates genomic segments within targeted chromatin directly with genomic bins via 3 C methods, revealing significant similarities in the chromatin structure at the population level, as demonstrated by optical reconstruction of chromatin architecture (ORCA), high-throughput, high-resolution, high-coverage, microscopy-based (Hi-M), and multiplexed imaging of nucleome architectures (MINA) methods59,62,64,67.
[268] The roles of cohesins in mitosis, meiosis, and human health and disease — The key difference between meiosis and mitosis is that meiotic cells undergo two cell divisions, meiosis I and meiosis II, without an intervening S phase. During meiosis I, the chromatin condenses as in mitosis and the sister chromatids are held together through a process called cohesion.
[269] Chromosome Organization and Dynamics during Interphase, Mitosis, and ... — Prophase of the first division of meiosis is a period of some of the most dynamic chromosome behavior. During this time, chromatin undergoes major reorganization that includes: (1) chromosome condensation and establishment of meiotic chromosome structure, (2) pairing of homologous chromosomes, and (3) dynamic chromosome movements.
[271] Mechanisms of chromosome behaviour during mitosis - PMC — Mitosis can be staged into individual phases. In interphase, most of the chromatin is decondensed in the nucleus so that individual chromosomes cannot be seen, and the microtubules are organized in a radial array from the centrosome. During prophase, the chromosomes become highly condensed, and the centrosomes begin to separate.
[275] Mitosis vs Meiosis - Science Notes and Projects — Home » Science Notes Posts » Biology » Mitosis vs Meiosis Specifically, crossing over occurs in meiosis I, so the chromosomes that separate into daughter cells are not identical to parent cells. In mitosis metaphase and anaphase II in meiosis, sister chromatids separate. Mitosis and meiosis have different numbers of cell division cycles, events in the stages of division, outcomes, and functions in organisms. While both mitosis and meiosis are forms of cell division, they have different outcomes. Mitosis: Sister chromatids separate, ensuring each daughter cell gets identical sets of chromosomes. While mitosis yields two daughter cells that are genetically identical (2n) to the parent cell, meiosis produces four haploid (n) cells that are genetically different from the parent cell.
[276] The Main Differences Between Mitosis and Meiosis - ThoughtCo — In eukaryotic cells, the production of new cells occurs as a result of mitosis and meiosis. However, mitosis involves the division of body cells, while meiosis involves the division of sex cells. Additionally, in mitosis, cell division results in two daughter cells, while meiosis yields four daughter cells through two rounds of division. Mitosis and meiosis are nuclear division processes that occur during cell division. The division of a cell occurs once in mitosis but twice in meiosis. As a result, two daughter cells are produced after mitosis and cytoplasmic division, while four daughter cells are produced after meiosis. Daughter cells resulting from mitosis are diploid, while those resulting from meiosis are haploid. Daughter Cells in Mitosis and Meiosis