1
|
Introini V, Kidiyoor GR, Porcella G, Cicuta P, Cosentino Lagomarsino M. Centripetal nuclear shape fluctuations associate with chromatin condensation in early prophase. Commun Biol 2023; 6:715. [PMID: 37438411 DOI: 10.1038/s42003-023-05074-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 06/26/2023] [Indexed: 07/14/2023] Open
Abstract
The nucleus plays a central role in several key cellular processes, including chromosome organisation, DNA replication and gene transcription. Recent work suggests an association between nuclear mechanics and cell-cycle progression, but many aspects of this connection remain unexplored. Here, by monitoring nuclear shape fluctuations at different cell cycle stages, we uncover increasing inward fluctuations in late G2 and in early prophase, which are initially transient, but develop into instabilities when approaching the nuclear-envelope breakdown. We demonstrate that such deformations correlate with chromatin condensation by perturbing both the chromatin and the cytoskeletal structures. We propose that the contrasting forces between an extensile stress and centripetal pulling from chromatin condensation could mechanically link chromosome condensation with nuclear-envelope breakdown, two main nuclear processes occurring during mitosis.
Collapse
Affiliation(s)
- Viola Introini
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge, CB3 0HE, UK
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge Biomedical Campus Keith Peters Building, Hills Rd, Cambridge, CB2 0XY, UK
| | - Gururaj Rao Kidiyoor
- IFOM, FIRC Institute of Molecular Oncology, Via Adamello 16, Milan, 20139, Italy
| | - Giancarlo Porcella
- IFOM, FIRC Institute of Molecular Oncology, Via Adamello 16, Milan, 20139, Italy
| | - Pietro Cicuta
- Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge, CB3 0HE, UK
| | - Marco Cosentino Lagomarsino
- IFOM, FIRC Institute of Molecular Oncology, Via Adamello 16, Milan, 20139, Italy.
- Dipartimento di Fisica, Università degli Studi di Milano and I.N.F.N., Via Celoria 16, Milan, 20133, Italy.
| |
Collapse
|
2
|
Schibler AC, Jevtic P, Pegoraro G, Levy DL, Misteli T. Identification of epigenetic modulators as determinants of nuclear size and shape. eLife 2023; 12:e80653. [PMID: 37219077 PMCID: PMC10259489 DOI: 10.7554/elife.80653] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2022] [Accepted: 05/04/2023] [Indexed: 05/24/2023] Open
Abstract
The shape and size of the human cell nucleus is highly variable among cell types and tissues. Changes in nuclear morphology are associated with disease, including cancer, as well as with premature and normal aging. Despite the very fundamental nature of nuclear morphology, the cellular factors that determine nuclear shape and size are not well understood. To identify regulators of nuclear architecture in a systematic and unbiased fashion, we performed a high-throughput imaging-based siRNA screen targeting 867 nuclear proteins including chromatin-associated proteins, epigenetic regulators, and nuclear envelope components. Using multiple morphometric parameters, and eliminating cell cycle effectors, we identified a set of novel determinants of nuclear size and shape. Interestingly, most identified factors altered nuclear morphology without affecting the levels of lamin proteins, which are known prominent regulators of nuclear shape. In contrast, a major group of nuclear shape regulators were modifiers of repressive heterochromatin. Biochemical and molecular analysis uncovered a direct physical interaction of histone H3 with lamin A mediated via combinatorial histone modifications. Furthermore, disease-causing lamin A mutations that result in disruption of nuclear shape inhibited lamin A-histone H3 interactions. Oncogenic histone H3.3 mutants defective for H3K27 methylation resulted in nuclear morphology abnormalities. Altogether, our results represent a systematic exploration of cellular factors involved in determining nuclear morphology and they identify the interaction of lamin A with histone H3 as an important contributor to nuclear morphology in human cells.
Collapse
Affiliation(s)
| | - Predrag Jevtic
- Department of Molecular Biology, University of WyomingLaramieUnited States
| | - Gianluca Pegoraro
- High Throughput Imaging Facility (HiTIF), National Cancer Institute, NIHBethesdaUnited States
| | - Daniel L Levy
- Department of Molecular Biology, University of WyomingLaramieUnited States
| | - Tom Misteli
- National Cancer InstituteBethesdaUnited States
| |
Collapse
|
3
|
Liu S, Li Y, Hong Y, Wang M, Zhang H, Ma J, Qu K, Huang G, Lu TJ. Mechanotherapy in oncology: Targeting nuclear mechanics and mechanotransduction. Adv Drug Deliv Rev 2023; 194:114722. [PMID: 36738968 DOI: 10.1016/j.addr.2023.114722] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 12/23/2022] [Accepted: 01/28/2023] [Indexed: 02/05/2023]
Abstract
Mechanotherapy is proposed as a new option for cancer treatment. Increasing evidence suggests that characteristic differences are present in the nuclear mechanics and mechanotransduction of cancer cells compared with those of normal cells. Recent advances in understanding nuclear mechanics and mechanotransduction provide not only further insights into the process of malignant transformation but also useful references for developing new therapeutic approaches. Herein, we present an overview of the alterations of nuclear mechanics and mechanotransduction in cancer cells and highlight their implications in cancer mechanotherapy.
Collapse
Affiliation(s)
- Shaobao Liu
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, PR China; MIIT Key Laboratory of Multifunctional Lightweight Materials and Structures, Nanjing University of Aeronautics, Nanjing 210016, PR China
| | - Yuan Li
- MOE Key Laboratory of Biomedical Information Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Yuan Hong
- MOE Key Laboratory of Biomedical Information Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China; National Science Foundation Science and Technology Center for Engineering Mechanobiology, Washington University, St. Louis, MO 63130, USA
| | - Ming Wang
- MOE Key Laboratory of Biomedical Information Engineering, School of Life Science and Technology, Xi'an Jiaotong University, Xi'an 710049, PR China; Bioinspired Engineering and Biomechanics Center (BEBC), Xi'an Jiaotong University, Xi'an 710049, PR China
| | - Hao Zhang
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, PR China; MIIT Key Laboratory of Multifunctional Lightweight Materials and Structures, Nanjing University of Aeronautics, Nanjing 210016, PR China
| | - Jinlu Ma
- Department of Radiation Oncology, the First Affiliated Hospital, Xian Jiaotong University, Xi'an 710061, PR China
| | - Kai Qu
- Department of Hepatobiliary Surgery, the First Affiliated Hospital, Xian Jiaotong University, Xi'an 710061, PR China
| | - Guoyou Huang
- Department of Engineering Mechanics, School of Civil Engineering, Wuhan University, Wuhan 430072, PR China.
| | - Tian Jian Lu
- State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, PR China; MIIT Key Laboratory of Multifunctional Lightweight Materials and Structures, Nanjing University of Aeronautics, Nanjing 210016, PR China.
| |
Collapse
|
4
|
Tuning between Nuclear Organization and Functionality in Health and Disease. Cells 2023; 12:cells12050706. [PMID: 36899842 PMCID: PMC10000962 DOI: 10.3390/cells12050706] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 02/08/2023] [Accepted: 02/20/2023] [Indexed: 02/25/2023] Open
Abstract
The organization of eukaryotic genome in the nucleus, a double-membraned organelle separated from the cytoplasm, is highly complex and dynamic. The functional architecture of the nucleus is confined by the layers of internal and cytoplasmic elements, including chromatin organization, nuclear envelope associated proteome and transport, nuclear-cytoskeletal contacts, and the mechano-regulatory signaling cascades. The size and morphology of the nucleus could impose a significant impact on nuclear mechanics, chromatin organization, gene expression, cell functionality and disease development. The maintenance of nuclear organization during genetic or physical perturbation is crucial for the viability and lifespan of the cell. Abnormal nuclear envelope morphologies, such as invagination and blebbing, have functional implications in several human disorders, including cancer, accelerated aging, thyroid disorders, and different types of neuro-muscular diseases. Despite the evident interplay between nuclear structure and nuclear function, our knowledge about the underlying molecular mechanisms for regulation of nuclear morphology and cell functionality during health and illness is rather poor. This review highlights the essential nuclear, cellular, and extracellular components that govern the organization of nuclei and functional consequences associated with nuclear morphometric aberrations. Finally, we discuss the recent developments with diagnostic and therapeutic implications targeting nuclear morphology in health and disease.
Collapse
|
5
|
PPAR-γ Agonist Pioglitazone Restored Mouse Liver mRNA Expression of Clock Genes and Inflammation-Related Genes Disrupted by Reversed Feeding. PPAR Res 2022; 2022:7537210. [PMID: 35663475 PMCID: PMC9162826 DOI: 10.1155/2022/7537210] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 04/27/2022] [Accepted: 05/03/2022] [Indexed: 11/17/2022] Open
Abstract
Introduction The master clock, which is located in the suprachiasmatic nucleus (SCN), harmonizes clock genes present in the liver to synchronize life rhythms and bioactivity with the surrounding environment. The reversed feeding disrupts the expression of clock genes in the liver. Recently, a novel role of PPAR-γ as a regulator in correlating circadian rhythm and metabolism was demonstrated. This study examined the influence of PPAR-γ agonist pioglitazone (PG) on the mRNA expression profile of principle clock genes and inflammation-related genes in the mouse liver disrupted by reverse feeding. Methods Mice were randomly assigned to daytime-feeding and nighttime-feeding groups. Mice in daytime-feeding groups received food from 7 AM to 7 PM, and mice in nighttime-feeding groups received food from 7 PM to 7 AM. PG was administered in the dose of 20 mg/kg per os as aqueous suspension 40 μl at 7 AM or 7 PM. Each group consisted of 12 animals. On day 8 of the feeding intervention, mice were sacrificed by cervical dislocation at noon (05 hours after light onset (HALO)) and midnight (HALO 17). Liver expressions of Bmal1, Clock, Rev-erb alpha, Cry1, Cry2, Per1, Per2, Cxcl5, Nrf2, and Ppar-γ were determined by quantitative reverse transcription PCR. Liver expression of PPAR-γ, pNF-κB, and IL-6 was determined by Western blotting. Glucose, ceruloplasmin, total cholesterol, triglyceride concentrations, and ALT and AST activities were measured in sera by photometric methods. The null hypothesis tested was that PG and the time of its administration have no influence on the clock gene expression impaired by reverse feeding. Results Administration of PG at 7 AM to nighttime-feeding mice did not reveal any influence on the expression of the clock or inflammation-related genes either at midnight or at noon. In the daytime-feeding group, PG intake at 7 PM led to an increase in Per2 and Rev-erb alpha mRNA at noon, an increase in Ppar-γ mRNA at midnight, and a decrease in Nfκb (p65) mRNA at noon. In general, PG administration at 7 PM slightly normalized the impaired expression of clock genes and increased anti-inflammatory potency impaired by reversed feeding. This pattern was supported by biochemical substrate levels—glucose, total cholesterol, ALT, and AST activities. The decrease in NF-κB led to the inhibition of serum ceruloplasmin levels as well as IL-6 in liver tissue. According to our data, PG intake at 7 PM exerts strong normalization of clock gene expression with a further increase in Nrf2 and, especially, Ppar-γ and PPAR-γ expression with inhibition of Nfκb and pNF-κB expression in daytime-feeding mice. These expression changes resulted in decreased hyperglycemia, hypercholesterolemia, ALT, and AST activities. Thus, PG had a potent chronopharmacological effect when administered at 7 PM to daytime-feeding mice. Conclusions Our study indicates that reversed feeding induced the disruption of mouse liver circadian expression pattern of clock genes accompanied by increasing Nfκb and pNF-κB and IL-6 expression and decreasing Nrf2 and PPAR-γ. Administration of PG restored the clock gene expression profile and decreased Nfκb, pNF-κB, and IL-6, as well as increased Nrf2, Ppar-γ, and PPAR-γ expression. PG intake at 7 PM was more effective than at 7 AM in reversed feeding mice.
Collapse
|
6
|
SWI/SNF chromatin remodeler complex within the reward pathway is required for behavioral adaptations to stress. Nat Commun 2022; 13:1807. [PMID: 35379786 PMCID: PMC8980038 DOI: 10.1038/s41467-022-29380-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 02/22/2022] [Indexed: 01/01/2023] Open
Abstract
Enduring behavioral changes upon stress exposure involve changes in gene expression sustained by epigenetic modifications in brain circuits, including the mesocorticolimbic pathway. Brahma (BRM) and Brahma Related Gene 1 (BRG1) are ATPase subunits of the SWI/SNF complexes involved in chromatin remodeling, a process essential to enduring plastic changes in gene expression. Here, we show that in mice, social defeat induces changes in BRG1 nuclear distribution. The inactivation of the Brg1/Smarca4 gene within dopamine-innervated regions or the constitutive inactivation of the Brm/Smarca2 gene leads to resilience to repeated social defeat and decreases the behavioral responses to cocaine without impacting midbrain dopamine neurons activity. Within striatal medium spiny neurons, Brg1 gene inactivation reduces the expression of stress- and cocaine-induced immediate early genes, increases levels of heterochromatin and at a global scale decreases chromatin accessibility. Altogether these data demonstrate the pivotal function of SWI/SNF complexes in behavioral and transcriptional adaptations to salient environmental challenges. Repeated exposure to social stressors in rodents results in behavioural changes. Here the authors show that behavioural adaptations to stress are associated with nuclear organization changes through SWI/SNF chromatin remodeler in specific neuronal populations of the mesolimbic system.
Collapse
|
7
|
Atanasova KR, Chakraborty S, Ratnayake R, Khare KD, Luesch H, Lele TP. An epigenetic small molecule screen to target abnormal nuclear morphology in human cells. Mol Biol Cell 2022; 33:ar45. [PMID: 35323046 PMCID: PMC9265153 DOI: 10.1091/mbc.e21-10-0528] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Irregular nuclear shapes are a hallmark of human cancers. Recent studies suggest that alterations to chromatin regulators may cause irregular nuclear morphologies. Here we screened an epigenetic small molecule library consisting of 145 compounds against chromatin regulators, for their ability to revert abnormal nuclear shapes that were induced by gene knockdown in non-cancerous MCF10A human mammary breast epithelial cells. We leveraged a previously validated quantitative Fourier approach to quantify the elliptical Fourier coefficient (EFC ratio) as a measure of nuclear irregularities, which allowed us to perform rigorous statistical analyses of screening data. Top hit compounds fell into three major mode of action categories, targeting three separate epigenetic modulation routes: 1) Histone deacetylase (HDAC) inhibitors; 2) Bromodomain and extra-terminal domain (BET) protein inhibitors; and 3) Methyl-transferase inhibitors. Some of the top hit compounds were also efficacious in reverting nuclear irregularities in MDA-MB-231 triple negative breast cancer cells and in PANC-1 pancreatic cancer cells in a cell type dependent manner. Regularization of nuclear shapes was compound-specific, cell-type specific, and dependent on the specific molecular perturbation that induced nuclear irregularities. Our approach of targeting nuclear abnormalities may be potentially useful in screening new types of cancer therapies targeted toward chromatin structure.
Collapse
Affiliation(s)
- Kalina R Atanasova
- Department of Medicinal Chemistry and Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, Gainesville FL 32610, USA
| | - Saptarshi Chakraborty
- Department of Biostatistics, State University of New York at Buffalo, Buffalo NY 14214, USA
| | - Ranjala Ratnayake
- Department of Medicinal Chemistry and Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, Gainesville FL 32610, USA
| | - Kshitij D Khare
- Department of Statistics, University of Florida, Gainesville FL 32611, USA
| | - Hendrik Luesch
- Department of Medicinal Chemistry and Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, Gainesville FL 32610, USA
| | - Tanmay P Lele
- Department of Biomedical Engineering, Department of Chemical Engineering, and Department of Translational Medical Sciences, Texas A&M University, College Station TX 77843, USA
| |
Collapse
|
8
|
Singh I, Lele TP. Nuclear Morphological Abnormalities in Cancer: A Search for Unifying Mechanisms. Results Probl Cell Differ 2022; 70:443-467. [PMID: 36348118 PMCID: PMC9722227 DOI: 10.1007/978-3-031-06573-6_16] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Irregularities in nuclear shape and/or alterations to nuclear size are a hallmark of malignancy in a broad range of cancer types. Though these abnormalities are commonly used for diagnostic purposes and are often used to assess cancer progression in the clinic, the mechanisms through which they occur are not well understood. Nuclear size alterations in cancer could potentially arise from aneuploidy, changes in osmotic coupling with the cytoplasm, and perturbations to nucleocytoplasmic transport. Nuclear shape changes may occur due to alterations to cell-generated mechanical stresses and/or alterations to nuclear structural components, which balance those stresses, such as the nuclear lamina and chromatin. A better understanding of the mechanisms underlying abnormal nuclear morphology and size may allow the development of new therapeutics to target nuclear aberrations in cancer.
Collapse
Affiliation(s)
- Ishita Singh
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA
| | - Tanmay P. Lele
- Department of Biomedical Engineering, Texas A&M University, College Station, TX, USA,Department of Chemical Engineering, University of Florida, Gainesville, FL, USA,Department of Translational Medical Sciences, Texas A&M University, Houston, TX, USA
| |
Collapse
|
9
|
Nuclear Dynamics and Chromatin Structure: Implications for Pancreatic Cancer. Cells 2021; 10:cells10102624. [PMID: 34685604 PMCID: PMC8534098 DOI: 10.3390/cells10102624] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/20/2021] [Accepted: 09/27/2021] [Indexed: 12/14/2022] Open
Abstract
Changes in nuclear shape have been extensively associated with the dynamics and functionality of cancer cells. In most normal cells, nuclei have a regular ellipsoid shape and minimal variation in nuclear size; however, an irregular nuclear contour and abnormal nuclear size is often observed in cancer, including pancreatic cancer. Furthermore, alterations in nuclear morphology have become the 'gold standard' for tumor staging and grading. Beyond the utility of altered nuclear morphology as a diagnostic tool in cancer, the implications of altered nuclear structure for the biology and behavior of cancer cells are profound as changes in nuclear morphology could impact cellular responses to physical strain, adaptation during migration, chromatin organization, and gene expression. Here, we aim to highlight and discuss the factors that regulate nuclear dynamics and their implications for pancreatic cancer biology.
Collapse
|
10
|
Nuclear Organization during Hepatogenesis in Zebrafish Requires Uhrf1. Genes (Basel) 2021; 12:genes12071081. [PMID: 34356097 PMCID: PMC8304062 DOI: 10.3390/genes12071081] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 07/08/2021] [Accepted: 07/12/2021] [Indexed: 01/07/2023] Open
Abstract
Acquisition of cellular fate during development is initiated and maintained by well-coordinated patterns of gene expression that are dictated by the epigenetic landscape and genome organization in the nucleus. While the epigenetic marks that mediate developmental gene expression patterns during organogenesis have been well studied, less is known about how epigenetic marks influence nuclear organization during development. This study examines the relationship between nuclear structure, chromatin accessibility, DNA methylation, and gene expression during hepatic outgrowth in zebrafish larvae. We investigate the relationship between these features using mutants that lack DNA methylation. Hepatocyte nuclear morphology was established coincident with hepatocyte differentiation at 80 h post-fertilization (hpf), and nuclear shape and size continued to change until the conclusion of outgrowth and morphogenesis at 120 hpf. Integrating ATAC-Seq analysis with DNA methylation profiling of zebrafish livers at 120 hpf showed that closed and highly methylated chromatin occupies most transposable elements and that open chromatin correlated with gene expression. DNA hypomethylation, due to mutation of genes encoding ubiquitin-like, containing PHD and RING Finger Domains 1 (uhrf1) and DNA methyltransferase (dnmt1), did not block hepatocyte differentiation, but had dramatic effects on nuclear organization. Hepatocytes in uhrf1 mutants have large, deformed nuclei with multiple nucleoli, downregulation of nucleolar genes, and a complete lack of the nuclear lamina. Loss of lamin B2 staining was phenocopied by dnmt1 mutation. Together, these data show that hepatocyte nuclear morphogenesis coincides with organ morphogenesis and outgrowth, and that DNA methylation directs chromatin organization, and, in turn, hepatocyte nuclear shape and size during liver development.
Collapse
|
11
|
Abstract
Membrane-bound organelles provide physical and functional compartmentalization of biological processes in eukaryotic cells. The characteristic shape and internal organization of these organelles is determined by a combination of multiple internal and external factors. The maintenance of the shape of nucleus, which houses the genetic material within a double membrane bilayer, is crucial for a seamless spatio-temporal control over nuclear and cellular functions. Dynamic morphological changes in the shape of nucleus facilitate various biological processes. Chromatin packaging, nuclear and cytosolic protein organization, and nuclear membrane lipid homeostasis are critical determinants of overall nuclear morphology. As such, a multitude of molecular players and pathways act together to regulate the nuclear shape. Here, we review the known mechanisms governing nuclear shape in various unicellular and multicellular organisms, including the non-spherical nuclei and non-lamin-related structural determinants. The review also touches upon cellular consequences of aberrant nuclear morphologies.
Collapse
Affiliation(s)
- Pallavi Deolal
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Krishnaveni Mishra
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
| |
Collapse
|
12
|
Deolal P, Male G, Mishra K. The challenge of staying in shape: nuclear size matters. Curr Genet 2021; 67:605-612. [PMID: 33779777 DOI: 10.1007/s00294-021-01176-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 03/06/2021] [Accepted: 03/08/2021] [Indexed: 10/21/2022]
Abstract
Cellular organelles have unique morphology and the organelle size to cell size ratio is regulated. Nucleus is one of the most prominent, usually round in shape, organelle of a eukaryotic cell that occupies 8-10% of cellular volume. The shape and size of nucleus is known to undergo remodeling during processes such as cell growth, division and certain stresses. Regulation of protein and lipid distribution at the nuclear envelope is crucial for preserving the nuclear morphology and size. As size and morphology are interlinked, altering one influences the other. In this perspective, we discuss the relationship between size and shape regulation of the nucleus.
Collapse
Affiliation(s)
- Pallavi Deolal
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Gurranna Male
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India
| | - Krishnaveni Mishra
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500046, India.
| |
Collapse
|
13
|
Goto C, Hara-Nishimura I, Tamura K. Regulation and Physiological Significance of the Nuclear Shape in Plants. FRONTIERS IN PLANT SCIENCE 2021; 12:673905. [PMID: 34177991 PMCID: PMC8222917 DOI: 10.3389/fpls.2021.673905] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 05/14/2021] [Indexed: 05/19/2023]
Abstract
The shape of plant nuclei varies among different species, tissues, and cell types. In Arabidopsis thaliana seedlings, nuclei in meristems and guard cells are nearly spherical, whereas those of epidermal cells in differentiated tissues are elongated spindle-shaped. The vegetative nuclei in pollen grains are irregularly shaped in angiosperms. In the past few decades, it has been revealed that several nuclear envelope (NE) proteins play the main role in the regulation of the nuclear shape in plants. Some plant NE proteins that regulate nuclear shape are also involved in nuclear or cellular functions, such as nuclear migration, maintenance of chromatin structure, gene expression, calcium and reactive oxygen species signaling, plant growth, reproduction, and plant immunity. The shape of the nucleus has been assessed both by labeling internal components (for instance chromatin) and by labeling membranes, including the NE or endoplasmic reticulum in interphase cells and viral-infected cells of plants. Changes in NE are correlated with the formation of invaginations of the NE, collectively called the nucleoplasmic reticulum. In this review, what is known and what is unknown about nuclear shape determination are presented, and the physiological significance of the control of the nuclear shape in plants is discussed.
Collapse
Affiliation(s)
- Chieko Goto
- Graduate School of Science, Kobe University, Kobe, Japan
| | | | - Kentaro Tamura
- School of Food and Nutritional Sciences, University of Shizuoka, Shizuoka, Japan
- *Correspondence: Kentaro Tamura,
| |
Collapse
|
14
|
Male G, Deolal P, Manda NK, Yagnik S, Mazumder A, Mishra K. Nucleolar size regulates nuclear envelope shape in Saccharomyces cerevisiae. J Cell Sci 2020; 133:jcs242172. [PMID: 32973112 DOI: 10.1242/jcs.242172] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Accepted: 09/17/2020] [Indexed: 12/12/2022] Open
Abstract
Nuclear shape and size are cell-type specific. Change in nuclear shape is seen during cell division, development and pathology. The nucleus of Saccharomycescerevisiae is spherical in interphase and becomes dumbbell shaped during mitotic division to facilitate the transfer of one nucleus to the daughter cell. Because yeast cells undergo closed mitosis, the nuclear envelope remains intact throughout the cell cycle. The pathways that regulate nuclear shape are not well characterized. The nucleus is organized into various subcompartments, with the nucleolus being the most prominent. We have conducted a candidate-based genetic screen for nuclear shape abnormalities in S. cerevisiae to ask whether the nucleolus influences nuclear shape. We find that increasing nucleolar volume triggers a non-isometric nuclear envelope expansion resulting in an abnormal nuclear envelope shape. We further show that the tethering of rDNA to the nuclear envelope is required for the appearance of these extensions.
Collapse
Affiliation(s)
- Gurranna Male
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India
| | - Pallavi Deolal
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India
| | - Naresh Kumar Manda
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India
| | - Shantam Yagnik
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/P, Gopanpally, Serilingampally Manda 500046l, Hyderabad, Telangana, India
| | - Aprotim Mazumder
- TIFR Centre for Interdisciplinary Sciences, Tata Institute of Fundamental Research Hyderabad, 36/P, Gopanpally, Serilingampally Manda 500046l, Hyderabad, Telangana, India
| | - Krishnaveni Mishra
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India
| |
Collapse
|
15
|
Feliksiak K, Witko T, Solarz D, Guzik M, Rajfur Z. Vimentin Association with Nuclear Grooves in Normal MEF 3T3 Cells. Int J Mol Sci 2020; 21:E7478. [PMID: 33050497 PMCID: PMC7590159 DOI: 10.3390/ijms21207478] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 10/06/2020] [Accepted: 10/08/2020] [Indexed: 12/25/2022] Open
Abstract
Vimentin, an intermediate filament protein present in leukocytes, blood vessel endothelial cells, and multiple mesenchymal cells, such as mouse embryonic fibroblasts (MEF 3T3), is crucial for various cellular processes, as well as for maintaining the integrity and durability (stability) of the cell cytoskeleton. Vimentin intermediate filaments (VIFs) adhere tightly to the nucleus and spread to the lamellipodium and tail of the cell, serving as a connector between the nucleus, and the cell's edges, especially in terms of transferring mechanical signals throughout the cell. How these signals are transmitted exactly remains under investigation. In the presented work, we propose that vimentin is involved in that transition by influencing the shape of the nucleus through the formation of nuclear blebs and grooves, as demonstrated by microscopic observations of healthy MEF (3T3) cells. Grooved, or "coffee beans" nuclei, have, to date, been noticed in several healthy cells; however, these structures are especially frequent in cancer cells-they serve as a significant marker for recognition of multiple cancers. We observed 288 MEF3T3 cells cultured on polyhydroxyoctanoate (PHO), polylactide (PLA), and glass, and we identified grooves, coaligned with vimentin fibers in the nuclei of 47% of cells cultured on PHO, 50% of cells on glass, and 59% of cells growing on PLA. We also observed nuclear blebs and associated their occurrence with the type of substrate used for cell culture. We propose that the higher rate of blebs in the nuclei of cells, cultured on PLA, is related to the microenvironmental features of the substrate, pH in particular.
Collapse
Affiliation(s)
- Karolina Feliksiak
- Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, 30-348 Kraków, Poland; (K.F.); (D.S.)
| | - Tomasz Witko
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, 30-239 Kraków, Poland;
| | - Daria Solarz
- Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, 30-348 Kraków, Poland; (K.F.); (D.S.)
| | - Maciej Guzik
- Jerzy Haber Institute of Catalysis and Surface Chemistry Polish Academy of Sciences, 30-239 Kraków, Poland;
| | - Zenon Rajfur
- Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, 30-348 Kraków, Poland; (K.F.); (D.S.)
| |
Collapse
|
16
|
Tamashunas AC, Tocco VJ, Matthews J, Zhang Q, Atanasova KR, Paschall L, Pathak S, Ratnayake R, Stephens AD, Luesch H, Licht JD, Lele TP. High-throughput gene screen reveals modulators of nuclear shape. Mol Biol Cell 2020; 31:1392-1402. [PMID: 32320319 PMCID: PMC7353136 DOI: 10.1091/mbc.e19-09-0520] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 03/30/2020] [Accepted: 04/14/2020] [Indexed: 12/11/2022] Open
Abstract
Irregular nuclear shapes characterized by blebs, lobules, micronuclei, or invaginations are hallmarks of many cancers and human pathologies. Despite the correlation between abnormal nuclear shape and human pathologies, the mechanism by which the cancer nucleus becomes misshapen is not fully understood. Motivated by recent evidence that modifying chromatin condensation can change nuclear morphology, we conducted a high-throughput RNAi screen to identify epigenetic regulators that are required to maintain normal nuclear shape in human breast epithelial MCF-10A cells. We silenced 608 genes in parallel using an epigenetics siRNA library and used an unbiased Fourier analysis approach to quantify nuclear contour irregularity from fluorescent images captured on a high-content microscope. Using this quantitative approach, which we validated with confocal microscopy, we significantly expand the list of epigenetic regulators that impact nuclear morphology.
Collapse
Affiliation(s)
| | | | - James Matthews
- Department of Medicinal Chemistry and Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, Gainesville, FL 32610
| | | | - Kalina R. Atanasova
- Department of Medicinal Chemistry and Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, Gainesville, FL 32610
| | | | | | - Ranjala Ratnayake
- Department of Medicinal Chemistry and Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, Gainesville, FL 32610
| | - Andrew D. Stephens
- Biology Department, University of Massachusetts Amherst, Amherst, MA 01003
| | - Hendrik Luesch
- Department of Medicinal Chemistry and Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, Gainesville, FL 32610
| | - Jonathan D. Licht
- Division of Hematology/Oncology, University of Florida Health Cancer Center, Gainesville, FL 32610
| | | |
Collapse
|
17
|
Stephens AD. Chromatin rigidity provides mechanical and genome protection. Mutat Res 2020; 821:111712. [PMID: 32590202 PMCID: PMC8186544 DOI: 10.1016/j.mrfmmm.2020.111712] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 06/05/2020] [Accepted: 06/15/2020] [Indexed: 12/31/2022]
Abstract
The nucleus is the organelle in the cell that contains the genome and its associate proteins which is collectively called chromatin. New work has shown that chromatin and its compaction level, dictated largely through histone modification state, provides rigidity to protect and stabilize the nucleus. Alterations in chromatin, its mechanics, and downstream loss of nuclear shape and stability are hallmarks of human disease. Weakened nuclear mechanics and abnormal morphology have been shown to cause rupturing of the nucleus which results in nuclear dysfunction including DNA damage. Thus, the rigidity provided by chromatin to maintain nuclear mechanical stability also provides its own protection from DNA damage via compartmentalization maintenance.
Collapse
Affiliation(s)
- Andrew D Stephens
- Biology Department, University of Massachusetts Amherst, Amherst, MA, 01003, United States.
| |
Collapse
|
18
|
Padilla-Benavides T, Haokip DT, Yoon Y, Reyes-Gutierrez P, Rivera-Pérez JA, Imbalzano AN. CK2-Dependent Phosphorylation of the Brg1 Chromatin Remodeling Enzyme Occurs during Mitosis. Int J Mol Sci 2020; 21:ijms21030923. [PMID: 32019271 PMCID: PMC7036769 DOI: 10.3390/ijms21030923] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 01/22/2020] [Accepted: 01/27/2020] [Indexed: 11/16/2022] Open
Abstract
Brg1 (Brahma-related gene 1) is one of two mutually exclusive ATPases that can act as the catalytic subunit of mammalian SWI/SNF (mSWI/SfigureNF) chromatin remodeling enzymes that facilitate utilization of the DNA in eukaryotic cells. Brg1 is a phospho-protein, and its activity is regulated by specific kinases and phosphatases. Previously, we showed that Brg1 interacts with and is phosphorylated by casein kinase 2 (CK2) in a manner that regulates myoblast proliferation. Here, we use biochemical and cell and molecular biology approaches to demonstrate that the Brg1-CK2 interaction occurred during mitosis in embryonic mouse somites and in primary myoblasts derived from satellite cells isolated from mouse skeletal muscle tissue. The interaction of CK2 with Brg1 and the incorporation of a number of other subunits into the mSWI/SNF enzyme complex were independent of CK2 enzymatic activity. CK2-mediated hyperphosphorylation of Brg1 was observed in mitotic cells derived from multiple cell types and organisms, suggesting functional conservation across tissues and species. The mitotically hyperphosphorylated form of Brg1 was localized with soluble chromatin, demonstrating that CK2-mediated phosphorylation of Brg1 is associated with specific partitioning of Brg1 within subcellular compartments. Thus, CK2 acts as a mitotic kinase that regulates Brg1 phosphorylation and subcellular localization.
Collapse
Affiliation(s)
- Teresita Padilla-Benavides
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA; (T.P.-B.); (D.T.H.); (P.R.-G.)
| | - Dominic T. Haokip
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA; (T.P.-B.); (D.T.H.); (P.R.-G.)
| | - Yeonsoo Yoon
- Department of Pediatrics, Division of Genes and Development, University of Massachusetts Medical School, Worcester, MA 01655, USA; (Y.Y.); (J.A.R.-P.)
| | - Pablo Reyes-Gutierrez
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA; (T.P.-B.); (D.T.H.); (P.R.-G.)
| | - Jaime A. Rivera-Pérez
- Department of Pediatrics, Division of Genes and Development, University of Massachusetts Medical School, Worcester, MA 01655, USA; (Y.Y.); (J.A.R.-P.)
| | - Anthony N. Imbalzano
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA; (T.P.-B.); (D.T.H.); (P.R.-G.)
- Correspondence: ; Tel.: +1-508-856-1029
| |
Collapse
|
19
|
Ahn JH, Cho MG, Sohn S, Lee JH. Inhibition of PP2A activity by H 2O 2 during mitosis disrupts nuclear envelope reassembly and alters nuclear shape. Exp Mol Med 2019; 51:1-18. [PMID: 31164634 PMCID: PMC6548778 DOI: 10.1038/s12276-019-0260-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 11/02/2018] [Accepted: 11/14/2018] [Indexed: 01/01/2023] Open
Abstract
Many types of cancer cells exhibit abnormal nuclear shapes induced by various molecular changes. However, whether reactive oxygen species (ROS) induce nuclear deformation has not been fully addressed. Here, we show that hydrogen peroxide (H2O2) treatment induced concentration-dependent alterations in nuclear shape that were abolished by pretreatment with the antioxidant N-acetyl-L-cysteine or by catalase overexpression. Interestingly, treatment with H2O2 induced nuclear shape alterations significantly more frequently in mitotic cells than in asynchronous cells, suggesting that H2O2 mainly affects nuclear envelope disassembly and/or reassembly processes. Because protein phosphatase 2 A (PP2A) activity is reported to be involved in nuclear envelope reassembly during mitosis, we investigated the possible involvement of PP2A. Indeed, H2O2 reduced the activity of PP2A, an effect that was mimicked by the PP1 and PP2A inhibitor okadaic acid. Moreover, overexpression of PP2A but not PP1 or PP4 partially rescued H2O2-induced alterations in nuclear shape, indicating that the decrease in PP2A activity induced by H2O2 is specifically involved in the observed nuclear shape alterations. We further show that treatment of mitotic cells with H2O2 induced the mislocalization of BAF (barrier-to-autointegration factor), a substrate of PP2A, during telophase. This effect was associated with Lamin A/C mislocalization and was rescued by PP2A overexpression. Collectively, our findings suggest that H2O2 preferentially affects mitotic cells through PP2A inhibition, which induces the subsequent mislocalization of BAF and Lamin A/C during nuclear envelope reassembly, leading to the formation of an abnormal nuclear shape. A class of harmful chemical compounds produces morphological abnormalities in the nucleus that may help promote tumor growth. Reactive oxygen species (ROS) are DNA- and protein-damaging molecules that originate both from environmental contaminants and as a byproduct of cellular metabolism or stress. Jae-Ho Lee and colleagues at Ajou University, Suwon, South Korea have now identified a mechanism by which ROS can disrupt the shape and structure of the nucleus. They show that ROS exposure reduces the ativity of an enzyme called PP2A, which is required for the targeted recruitment of proteins that rebuild the membrane envelope surrounding the nucleus after cell division. Perturbations in this envelope can potentially contribute to damage to the chromosomal DNA within the nucleus, creating conditions that can trigger or accelerate the process of tumorigenesis.
Collapse
Affiliation(s)
- Ju-Hyun Ahn
- Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon, 443-721, South Korea.,Genomic Instability Research Center, Ajou University School of Medicine, Suwon, 443-721, South Korea.,Department of Biomedical Sciences, The Graduate School of Ajou University, Suwon, 443-721, South Korea
| | - Min-Guk Cho
- Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon, 443-721, South Korea.,Genomic Instability Research Center, Ajou University School of Medicine, Suwon, 443-721, South Korea.,Department of Biomedical Sciences, The Graduate School of Ajou University, Suwon, 443-721, South Korea
| | - Seonghyang Sohn
- Department of Biomedical Sciences, The Graduate School of Ajou University, Suwon, 443-721, South Korea.,Department of Microbiology, Ajou University School of Medicine, Suwon, 443-721, South Korea
| | - Jae-Ho Lee
- Department of Biochemistry and Molecular Biology, Ajou University School of Medicine, Suwon, 443-721, South Korea. .,Genomic Instability Research Center, Ajou University School of Medicine, Suwon, 443-721, South Korea. .,Department of Biomedical Sciences, The Graduate School of Ajou University, Suwon, 443-721, South Korea.
| |
Collapse
|
20
|
Stephens AD, Banigan EJ, Marko JF. Chromatin's physical properties shape the nucleus and its functions. Curr Opin Cell Biol 2019; 58:76-84. [PMID: 30889417 PMCID: PMC6692209 DOI: 10.1016/j.ceb.2019.02.006] [Citation(s) in RCA: 99] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 02/06/2019] [Accepted: 02/20/2019] [Indexed: 12/13/2022]
Abstract
The cell nucleus encloses, organizes, and protects the genome. Chromatin maintains nuclear mechanical stability and shape in coordination with lamins and the cytoskeleton. Abnormal nuclear shape is a diagnostic marker for human diseases, and it can cause nuclear dysfunction. Chromatin mechanics underlies this link, as alterations to chromatin and its physical properties can disrupt or rescue nuclear shape. The cell can regulate nuclear shape through mechanotransduction pathways that sense and respond to extracellular cues, thus modulating chromatin compaction and rigidity. These findings reveal how chromatin's physical properties can regulate cellular function and drive abnormal nuclear morphology and dysfunction in disease.
Collapse
Affiliation(s)
- Andrew D Stephens
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, United States.
| | - Edward J Banigan
- Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - John F Marko
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208, United States; Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208, United States.
| |
Collapse
|
21
|
Kent IA, Zhang Q, Katiyar A, Li Y, Pathak S, Dickinson RB, Lele TP. Apical cell protrusions cause vertical deformation of the soft cancer nucleus. J Cell Physiol 2019; 234:20675-20684. [PMID: 31006858 DOI: 10.1002/jcp.28672] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Accepted: 03/21/2019] [Indexed: 01/17/2023]
Abstract
Breast cancer nuclei have highly irregular shapes, which are diagnostic and prognostic markers of breast cancer progression. The mechanisms by which irregular cancer nuclear shapes develop are not well understood. Here we report the existence of vertical, apical cell protrusions in cultured MDA-MB-231 breast cancer cells. Once formed, these protrusions persist over time scales of hours and are associated with vertically upward nuclear deformations. They are absent in normal mammary epithelial cells (MCF-10A cells). Microtubule disruption enriched these protrusions preferentially in MDA-MB-231 cells compared with MCF-10A cells, whereas inhibition of nonmuscle myosin II (NMMII) abolished this enrichment. Dynamic confocal imaging of the vertical cell and nuclear shape revealed that the apical cell protrusions form first, and in response, the nucleus deforms and/or subsequently gets vertically extruded into the apical protrusion. Overexpression of lamin A/C in MDA-MB-231 cells reduced nuclear deformation in apical protrusions. These data highlight the role of mechanical stresses generated by moving boundaries, as well as abnormal nuclear mechanics in the development of abnormal nuclear shapes in breast cancer cells.
Collapse
Affiliation(s)
- Ian A Kent
- Department of Chemical Engineering, University of Florida, Gainesville, Florida
| | - Qiao Zhang
- Department of Chemical Engineering, University of Florida, Gainesville, Florida
| | - Aditya Katiyar
- Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida
| | - Yuan Li
- Department of Chemical Engineering, University of Florida, Gainesville, Florida
| | - Shreya Pathak
- Department of Chemical Engineering, University of Florida, Gainesville, Florida
| | - Richard B Dickinson
- Department of Chemical Engineering, University of Florida, Gainesville, Florida
| | - Tanmay P Lele
- Department of Chemical Engineering, University of Florida, Gainesville, Florida
| |
Collapse
|
22
|
Wu Q, Madany P, Dobson JR, Schnabl JM, Sharma S, Smith TC, van Wijnen AJ, Stein JL, Lian JB, Stein GS, Muthuswami R, Imbalzano AN, Nickerson JA. The BRG1 chromatin remodeling enzyme links cancer cell metabolism and proliferation. Oncotarget 2018; 7:38270-38281. [PMID: 27223259 PMCID: PMC5122388 DOI: 10.18632/oncotarget.9505] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 05/01/2016] [Indexed: 12/20/2022] Open
Abstract
Cancer cells reprogram cellular metabolism to meet the demands of growth. Identification of the regulatory machinery that regulates cancer-specific metabolic changes may open new avenues for anti-cancer therapeutics. The epigenetic regulator BRG1 is a catalytic ATPase for some mammalian SWI/SNF chromatin remodeling enzymes. BRG1 is a well-characterized tumor suppressor in some human cancers, but is frequently overexpressed without mutation in other cancers, including breast cancer. Here we demonstrate that BRG1 upregulates de novo lipogenesis and that this is crucial for cancer cell proliferation. Knockdown of BRG1 attenuates lipid synthesis by impairing the transcription of enzymes catalyzing fatty acid and lipid synthesis. Remarkably, exogenous addition of palmitate, the key intermediate in fatty acid synthesis, rescued the cancer cell proliferation defect caused by BRG1 knockdown. Our work suggests that targeting BRG1 to reduce lipid metabolism and, thereby, to reduce proliferation, has promise for epigenetic therapy in triple negative breast cancer.
Collapse
Affiliation(s)
- Qiong Wu
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Pasil Madany
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Jason R Dobson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Jake M Schnabl
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Soni Sharma
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Tara C Smith
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Andre J van Wijnen
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN, USA
| | - Janet L Stein
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, WA, USA
| | - Jane B Lian
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, WA, USA
| | - Gary S Stein
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, WA, USA
| | - Rohini Muthuswami
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Anthony N Imbalzano
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Jeffrey A Nickerson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| |
Collapse
|
23
|
Comprehensive assessment of the expression of the SWI/SNF complex defines two distinct prognostic subtypes of ovarian clear cell carcinoma. Oncotarget 2018; 7:54758-54770. [PMID: 27340867 PMCID: PMC5342379 DOI: 10.18632/oncotarget.10181] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 06/01/2016] [Indexed: 12/18/2022] Open
Abstract
Somatic mutations in the ARID1A tumor-suppressor gene have been frequently identified in ovarian clear cell carcinoma (CCC) cases. BAF250a encoded by ARID1A is a member of the SWI/SNF complex, but the expression and mutation status of other SWI/SNF subunits have not been explored. The current study aimed to elucidate the biological and clinical significance of the SWI/SNF complex subunits, by assessing the expression and mutation status of SWI/SNF subunits, and distinct genomic aberrations associated with their expression. Of 82 CCC specimens, 38 samples presented no BAF250a expression, and 50 samples exhibited the loss of at least one subunit of the SWI/SNF complex. Cases which lack at least one SWI/SNF complex component exhibited significantly more advanced stages, faster growth and stronger nuclear atypia compared with SWI/SNF-positive samples (p<0.05). Although BAF250a expression is not related to poor prognosis, the group presenting the loss of at least one SWI/SNF complex subunit exhibited significantly shorter overall and progression-free survivals (p<0.05). A multivariate analysis suggested that the expression status of the SWI/SNF complex serves as an independent prognostic factor (p<0.005). The cases positive for all SWI/SNF subunits demonstrated significantly greater DNA copy number alterations, such as amplification at chromosomes 8q.24.3 and 20q.13.2-20q.13.33 (including ZNF217) and deletion at chromosomes 13q12.11-13q14.3 (including RB1), 17p13.2-17p13.1 (including TP53) and 19p13.2-19p13.12. In conclusion, the CCCs exhibiting the loss of one or multiple SWI/SNF complex subunits demonstrated aggressive behaviors and poor prognosis, whereas the CCCs with positive expression for all SWI/SNF components presented more copy number alterations and a favorable prognosis.
Collapse
|
24
|
Stephens AD, Liu PZ, Banigan EJ, Almassalha LM, Backman V, Adam SA, Goldman RD, Marko JF. Chromatin histone modifications and rigidity affect nuclear morphology independent of lamins. Mol Biol Cell 2018; 29:220-233. [PMID: 29142071 PMCID: PMC5909933 DOI: 10.1091/mbc.e17-06-0410] [Citation(s) in RCA: 206] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Revised: 10/17/2017] [Accepted: 11/08/2017] [Indexed: 01/29/2023] Open
Abstract
Nuclear shape and architecture influence gene localization, mechanotransduction, transcription, and cell function. Abnormal nuclear morphology and protrusions termed "blebs" are diagnostic markers for many human afflictions including heart disease, aging, progeria, and cancer. Nuclear blebs are associated with both lamin and chromatin alterations. A number of prior studies suggest that lamins dictate nuclear morphology, but the contributions of altered chromatin compaction remain unclear. We show that chromatin histone modification state dictates nuclear rigidity, and modulating it is sufficient to both induce and suppress nuclear blebs. Treatment of mammalian cells with histone deacetylase inhibitors to increase euchromatin or histone methyltransferase inhibitors to decrease heterochromatin results in a softer nucleus and nuclear blebbing, without perturbing lamins. Conversely, treatment with histone demethylase inhibitors increases heterochromatin and chromatin nuclear rigidity, which results in reduced nuclear blebbing in lamin B1 null nuclei. Notably, increased heterochromatin also rescues nuclear morphology in a model cell line for the accelerated aging disease Hutchinson-Gilford progeria syndrome caused by mutant lamin A, as well as cells from patients with the disease. Thus, chromatin histone modification state is a major determinant of nuclear blebbing and morphology via its contribution to nuclear rigidity.
Collapse
Affiliation(s)
- Andrew D Stephens
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
| | - Patrick Z Liu
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208
| | - Edward J Banigan
- Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208.,Institute for Medical Engineering and Science, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Luay M Almassalha
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208
| | - Vadim Backman
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208
| | - Stephen A Adam
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - Robert D Goldman
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611
| | - John F Marko
- Department of Molecular Biosciences, Northwestern University, Evanston, IL 60208.,Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208
| |
Collapse
|
25
|
Wu Q, Sharma S, Cui H, LeBlanc SE, Zhang H, Muthuswami R, Nickerson JA, Imbalzano AN. Targeting the chromatin remodeling enzyme BRG1 increases the efficacy of chemotherapy drugs in breast cancer cells. Oncotarget 2017; 7:27158-75. [PMID: 27029062 PMCID: PMC5053639 DOI: 10.18632/oncotarget.8384] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Accepted: 03/16/2016] [Indexed: 12/31/2022] Open
Abstract
Brahma related gene product 1 (BRG1) is an ATPase that drives the catalytic activity of a subset of the mammalian SWI/SNF chromatin remodeling enzymes. BRG1 is overexpressed in most human breast cancer tumors without evidence of mutation and is required for breast cancer cell proliferation. We demonstrate that knockdown of BRG1 sensitized triple negative breast cancer cells to chemotherapeutic drugs used to treat breast cancer. An inhibitor of the BRG1 bromodomain had no effect on breast cancer cell viability, but an inhibitory molecule that targets the BRG1 ATPase activity recapitulated the increased drug efficacy observed in the presence of BRG1 knockdown. We further demonstrate that inhibition of BRG1 ATPase activity blocks the induction of ABC transporter genes by these chemotherapeutic drugs and that BRG1 binds to ABC transporter gene promoters. This inhibition increased intracellular concentrations of the drugs, providing a likely mechanism for the increased chemosensitivity. Since ABC transporters and their induction by chemotherapy drugs are a major cause of chemoresistance and treatment failure, these results support the idea that targeting the enzymatic activity of BRG1 would be an effective adjuvant therapy for breast cancer.
Collapse
Affiliation(s)
- Qiong Wu
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Soni Sharma
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Hang Cui
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA.,Abace Biotech Co Ltd., Yi Zhuang Biomedical Park, BDA, Beijing, China
| | - Scott E LeBlanc
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Hong Zhang
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Rohini Muthuswami
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, Delhi, India
| | - Jeffrey A Nickerson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| | - Anthony N Imbalzano
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, MA, USA
| |
Collapse
|
26
|
Skinner BM, Johnson EEP. Nuclear morphologies: their diversity and functional relevance. Chromosoma 2017; 126:195-212. [PMID: 27631793 PMCID: PMC5371643 DOI: 10.1007/s00412-016-0614-5] [Citation(s) in RCA: 104] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 08/17/2016] [Indexed: 12/20/2022]
Abstract
Studies of chromosome and genome biology often focus on condensed chromatin in the form of chromosomes and neglect the non-dividing cells. Even when interphase nuclei are considered, they are often then treated as interchangeable round objects. However, different cell types can have very different nuclear shapes, and these shapes have impacts on cellular function; indeed, many pathologies are linked with alterations to nuclear shape. In this review, we describe some of the nuclear morphologies beyond the spherical and ovoid. Many of the leukocytes of the immune system have lobed nuclei, which aid their flexibility and migration; smooth muscle cells have a spindle shaped nucleus, which must deform during muscle contractions; spermatozoa have highly condensed nuclei which adopt varied shapes, potentially associated with swimming efficiency. Nuclei are not passive passengers within the cell. There are clear effects of nuclear shape on the transcriptional activity of the cell. Recent work has shown that regulation of gene expression can be influenced by nuclear morphology, and that cells can drastically remodel their chromatin during differentiation. The link between the nucleoskeleton and the cytoskeleton at the nuclear envelope provides a mechanism for transmission of mechanical forces into the nucleus, directly affecting chromatin compaction and organisation.
Collapse
Affiliation(s)
- Benjamin M Skinner
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK.
| | - Emma E P Johnson
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| |
Collapse
|
27
|
Barutcu AR, Lian JB, Stein JL, Stein GS, Imbalzano AN. The connection between BRG1, CTCF and topoisomerases at TAD boundaries. Nucleus 2017; 8:150-155. [PMID: 28060558 PMCID: PMC5403164 DOI: 10.1080/19491034.2016.1276145] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
The eukaryotic genome is partitioned into topologically associating domains (TADs). Despite recent advances characterizing TADs and TAD boundaries, the organization of these structures is an important dimension of genome architecture and function that is not well understood. Recently, we demonstrated that knockdown of BRG1, an ATPase driving the chromatin remodeling activity of mammalian SWI/SNF enzymes, globally alters long-range genomic interactions and results in a reduction of TAD boundary strength. We provided evidence suggesting that this effect may be due to BRG1 affecting nucleosome occupancy around CTCF sites present at TAD boundaries. In this review, we elaborate on our findings and speculate that BRG1 may contribute to the regulation of the structural and functional properties of chromatin at TAD boundaries by affecting the function or the recruitment of CTCF and DNA topoisomerase complexes.
Collapse
Affiliation(s)
- A Rasim Barutcu
- a Department of Cell and Developmental Biology , University of Massachusetts Medical School , Worcester , MA , USA
| | - Jane B Lian
- b Department of Biochemistry , University of Vermont College of Medicine , Burlington , VT , USA
| | - Janet L Stein
- b Department of Biochemistry , University of Vermont College of Medicine , Burlington , VT , USA
| | - Gary S Stein
- b Department of Biochemistry , University of Vermont College of Medicine , Burlington , VT , USA
| | - Anthony N Imbalzano
- a Department of Cell and Developmental Biology , University of Massachusetts Medical School , Worcester , MA , USA
| |
Collapse
|
28
|
Tang JR, Mat Isa NA, Ch’ng ES. Evaluating Nuclear Membrane Irregularity for the Classification of Cervical Squamous Epithelial Cells. PLoS One 2016; 11:e0164389. [PMID: 27741266 PMCID: PMC5065206 DOI: 10.1371/journal.pone.0164389] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 09/23/2016] [Indexed: 01/23/2023] Open
Abstract
Pap test involves searching of morphological changes in cervical squamous epithelial cells by pathologists or cytotechnologists to identify potential cancerous cells in the cervix. Nuclear membrane irregularity is one of the morphological changes of malignancy. This paper proposes two novel techniques for the evaluation of nuclear membrane irregularity. The first technique, namely, penalty-driven smoothing analysis, introduces different penalty values for nuclear membrane contour with different degrees of irregularity. The second technique, which can be subdivided into mean- or median-type residual-based analysis, computes the number of points of nuclear membrane contour that deviates from the mean or median of the nuclear membrane contour. Performance of the proposed techniques was compared to three state-of-the-art techniques, namely, radial asymmetric, shape factor, and rim difference. Friedman and post hoc tests using Holm, Shaffer, and Bergmann procedures returned significant differences for all the three classes, i.e., negative for intraepithelial lesion or malignancy (NILM) versus low grade squamous intraepithelial lesion (LSIL), NILM versus high grade squamous intraepithelial lesion (HSIL), and LSIL versus HSIL when the span value equaled 3 was employed with linear penalty function. When span values equaled 5, 7, and 9, NILM versus LSIL and HSIL showed significant differences regardless of the penalty functions. In addition, the results of penalty-driven smoothing analysis were comparable with those of other state-of-the-art techniques. Residual-based analysis returned significant differences for the comparison among the three diagnostic classes. Findings of this study proved the significance of nuclear membrane irregularity as one of the features to differentiate the different diagnostic classes of cervical squamous epithelial cells.
Collapse
Affiliation(s)
- Jing Rui Tang
- Imaging and Intelligent Systems Research Team, School of Electrical and Electronic Engineering, Universiti Sains Malaysia, Nibong Tebal, Pulau Pinang, Malaysia
| | - Nor Ashidi Mat Isa
- Imaging and Intelligent Systems Research Team, School of Electrical and Electronic Engineering, Universiti Sains Malaysia, Nibong Tebal, Pulau Pinang, Malaysia
| | - Ewe Seng Ch’ng
- Advanced Medical and Dental Institute, Universiti Sains Malaysia, Bertam, Kepala Batas, Pulau Pinang, Malaysia
| |
Collapse
|
29
|
Barutcu AR, Lajoie BR, Fritz AJ, McCord RP, Nickerson JA, van Wijnen AJ, Lian JB, Stein JL, Dekker J, Stein GS, Imbalzano AN. SMARCA4 regulates gene expression and higher-order chromatin structure in proliferating mammary epithelial cells. Genome Res 2016; 26:1188-201. [PMID: 27435934 PMCID: PMC5052043 DOI: 10.1101/gr.201624.115] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 07/08/2016] [Indexed: 01/20/2023]
Abstract
The packaging of DNA into chromatin plays an important role in transcriptional regulation and nuclear processes. Brahma-related gene-1 SMARCA4 (also known as BRG1), the essential ATPase subunit of the mammalian SWI/SNF chromatin remodeling complex, uses the energy from ATP hydrolysis to disrupt nucleosomes at target regions. Although the transcriptional role of SMARCA4 at gene promoters is well-studied, less is known about its role in higher-order genome organization. SMARCA4 knockdown in human mammary epithelial MCF-10A cells resulted in 176 up-regulated genes, including many related to lipid and calcium metabolism, and 1292 down-regulated genes, some of which encode extracellular matrix (ECM) components that can exert mechanical forces and affect nuclear structure. ChIP-seq analysis of SMARCA4 localization and SMARCA4-bound super-enhancers demonstrated extensive binding at intergenic regions. Furthermore, Hi-C analysis showed extensive SMARCA4-mediated alterations in higher-order genome organization at multiple resolutions. First, SMARCA4 knockdown resulted in clustering of intra- and inter-subtelomeric regions, demonstrating a novel role for SMARCA4 in telomere organization. SMARCA4 binding was enriched at topologically associating domain (TAD) boundaries, and SMARCA4 knockdown resulted in weakening of TAD boundary strength. Taken together, these findings provide a dynamic view of SMARCA4-dependent changes in higher-order chromatin organization and gene expression, identifying SMARCA4 as a novel component of chromatin organization.
Collapse
Affiliation(s)
- A Rasim Barutcu
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
| | - Bryan R Lajoie
- Program in Systems Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Andrew J Fritz
- Department of Biochemistry, University of Vermont College of Medicine, Burlington, Vermont 05405, USA
| | - Rachel P McCord
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996, USA
| | - Jeffrey A Nickerson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
| | - Andre J van Wijnen
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905, USA
| | - Jane B Lian
- Department of Biochemistry, University of Vermont College of Medicine, Burlington, Vermont 05405, USA
| | - Janet L Stein
- Department of Biochemistry, University of Vermont College of Medicine, Burlington, Vermont 05405, USA
| | - Job Dekker
- Program in Systems Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA; Howard Hughes Medical Institute, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
| | - Gary S Stein
- Department of Biochemistry, University of Vermont College of Medicine, Burlington, Vermont 05405, USA
| | - Anthony N Imbalzano
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655, USA
| |
Collapse
|
30
|
Jin Y, Ren N, Li S, Fu X, Sun X, Men Y, Xu Z, Zhang J, Xie Y, Xia M, Gao J. Deletion of Brg1 causes abnormal hair cell planer polarity, hair cell anchorage, and scar formation in mouse cochlea. Sci Rep 2016; 6:27124. [PMID: 27255603 PMCID: PMC4891731 DOI: 10.1038/srep27124] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 05/12/2016] [Indexed: 12/28/2022] Open
Abstract
Hair cells (HCs) are mechanosensors that play crucial roles in perceiving sound, acceleration, and fluid motion. The precise architecture of the auditory epithelium and its repair after HC loss is indispensable to the function of organ of Corti (OC). In this study, we showed that Brg1 was highly expressed in auditory HCs. Specific deletion of Brg1 in postnatal HCs resulted in rapid HC degeneration and profound deafness in mice. Further experiments showed that cell-intrinsic polarity of HCs was abolished, docking of outer hair cells (OHCs) by Deiter’s cells (DCs) failed, and scar formation in the reticular lamina was deficient. We demonstrated that Brg1 ablation disrupted the Gαi/Insc/LGN and aPKC asymmetric distributions, without overt effects on the core planer cell polarity (PCP) pathway. We also demonstrated that Brg1-deficient HCs underwent apoptosis, and that leakage in the reticular lamina caused by deficient scar formation shifted the mode of OHC death from apoptosis to necrosis. Together, these data demonstrated a requirement for Brg1 activity in HC development and suggested a role for Brg1 in the proper cellular structure formation of HCs.
Collapse
Affiliation(s)
- Yecheng Jin
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan 250100, China
| | - Naixia Ren
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan 250100, China
| | - Shiwei Li
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan 250100, China
| | - Xiaolong Fu
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan 250100, China
| | - Xiaoyang Sun
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan 250100, China
| | - Yuqin Men
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan 250100, China
| | - Zhigang Xu
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan 250100, China
| | - Jian Zhang
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan 250100, China
| | - Yue Xie
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan 250100, China
| | - Ming Xia
- Department of Otolaryngology-Head and Neck Surgery, The Second Hospital of Shandong University, Jinan 250033, China
| | - Jiangang Gao
- School of Life Science and Key Laboratory of the Ministry of Education for Experimental Teratology, Shandong University, Jinan 250100, China
| |
Collapse
|
31
|
Matsumoto A, Sakamoto C, Matsumori H, Katahira J, Yasuda Y, Yoshidome K, Tsujimoto M, Goldberg IG, Matsuura N, Nakao M, Saitoh N, Hieda M. Loss of the integral nuclear envelope protein SUN1 induces alteration of nucleoli. Nucleus 2016; 7:68-83. [PMID: 26962703 DOI: 10.1080/19491034.2016.1149664] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
A supervised machine learning algorithm, which is qualified for image classification and analyzing similarities, is based on multiple discriminative morphological features that are automatically assembled during the learning processes. The algorithm is suitable for population-based analysis of images of biological materials that are generally complex and heterogeneous. Here we used the algorithm wndchrm to quantify the effects on nucleolar morphology of the loss of the components of nuclear envelope in a human mammary epithelial cell line. The linker of nucleoskeleton and cytoskeleton (LINC) complex, an assembly of nuclear envelope proteins comprising mainly members of the SUN and nesprin families, connects the nuclear lamina and cytoskeletal filaments. The components of the LINC complex are markedly deficient in breast cancer tissues. We found that a reduction in the levels of SUN1, SUN2, and lamin A/C led to significant changes in morphologies that were computationally classified using wndchrm with approximately 100% accuracy. In particular, depletion of SUN1 caused nucleolar hypertrophy and reduced rRNA synthesis. Further, wndchrm revealed a consistent negative correlation between SUN1 expression and the size of nucleoli in human breast cancer tissues. Our unbiased morphological quantitation strategies using wndchrm revealed an unexpected link between the components of the LINC complex and the morphologies of nucleoli that serves as an indicator of the malignant phenotype of breast cancer cells.
Collapse
Affiliation(s)
- Ayaka Matsumoto
- a Osaka University , Graduate School of Medicine and Health Science , Suita City , Osaka , Japan
| | - Chiyomi Sakamoto
- b Department of Medical Cell Biology , Institute of Molecular Embryology and Genetics, Kumamoto University , Kumamoto , Japan
| | - Haruka Matsumori
- b Department of Medical Cell Biology , Institute of Molecular Embryology and Genetics, Kumamoto University , Kumamoto , Japan
| | - Jun Katahira
- c Osaka University , Graduate School of Frontier Bioscience , Suita City , Osaka , Japan
| | - Yoko Yasuda
- b Department of Medical Cell Biology , Institute of Molecular Embryology and Genetics, Kumamoto University , Kumamoto , Japan
| | - Katsuhide Yoshidome
- d Department of Breast Surgery , Osaka Police Hospital , Tennoji-ku , Osaka , Japan
| | - Masahiko Tsujimoto
- e Department of Pathology , Osaka Police Hospital , Tennoji-ku , Osaka , Japan
| | - Ilya G Goldberg
- f Image Informatics and Computational Biology Unit, Laboratory of Genetics , National Institute on Aging, National Institutes of Health , Baltimore , MD USA
| | - Nariaki Matsuura
- a Osaka University , Graduate School of Medicine and Health Science , Suita City , Osaka , Japan
| | - Mitsuyoshi Nakao
- b Department of Medical Cell Biology , Institute of Molecular Embryology and Genetics, Kumamoto University , Kumamoto , Japan.,g Core Research for Evolutional Science and Technology (CREST) , Japan Agency for Medical Research and Development , Tokyo , Japan
| | - Noriko Saitoh
- b Department of Medical Cell Biology , Institute of Molecular Embryology and Genetics, Kumamoto University , Kumamoto , Japan
| | - Miki Hieda
- a Osaka University , Graduate School of Medicine and Health Science , Suita City , Osaka , Japan
| |
Collapse
|
32
|
Barragán-Vargas C, Montano-Frías J, Ávila Rosales G, Godínez-Reyes CR, Acevedo-Whitehouse K. Transformation of the genital epithelial tract occurs early in California sea lion development. ROYAL SOCIETY OPEN SCIENCE 2016; 3:150419. [PMID: 27069641 PMCID: PMC4821252 DOI: 10.1098/rsos.150419] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 02/12/2016] [Indexed: 05/08/2023]
Abstract
An unusually high prevalence of metastatic urogenital carcinoma has been observed in free-ranging California sea lions stranded off the coast of California in the past two decades. No cases have been reported for sea lions in the relatively unpolluted Gulf of California. We investigated occurrence of genital epithelial transformation in 60 sea lions (n=57 pups and 3 adult females) from the Gulf of California and examined whether infection by a viral pathogen previously found to be associated with urogenital carcinoma accounted for such alterations. We also explored the contribution of MHC class II gene expression on transformation. Cellular alterations, such as squamous cell atypia (ASC), atypical squamous cells of undetermined significance (ASCUS) and low-grade squamous intraepithelial lesions were observed in 42% of the pups and in 67% of the adult females. Normal genital epithelium was more common in male than female pups. ASC was five times more likely to occur in older pups. Epithelial alterations were unrelated to infection by the potentially oncogenic otarine type I gammaherpesvirus (OtHV-1), but ASCUS was more common in pups with marked and severe inflammation. Expression of MHC class II DRB loci (Zaca DRB-D) by peripheral antigen-presenting leucocytes showed a slightly 'protective' effect for ASC. We propose that transformation of the California sea lion genital epithelium is relatively common in young animals, increases with age and is probably the result of infection by an unidentified pathogen. Expression of a specific MHC class II gene, suggestive of presentation of specific antigenic peptides to immune effectors, appears to lower the risk of transformation. Our study provides the first evidence that epithelial transformation of the California sea lion genital tract is relatively common, even from an early age, and raises questions regarding differences in sea lion cancer-detection and -repair success between geographical regions.
Collapse
Affiliation(s)
- Cecilia Barragán-Vargas
- Unit for Basic and Applied Microbiology, School of Natural Sciences, Autonomous University of Queretaro, Avenida de las Ciencias S/N, Queretaro 76230, Mexico
| | - Jorge Montano-Frías
- Unit for Basic and Applied Microbiology, School of Natural Sciences, Autonomous University of Queretaro, Avenida de las Ciencias S/N, Queretaro 76230, Mexico
| | - Germán Ávila Rosales
- Department of Pathology, Instituto Mexicano del Seguro Social, Queretaro 76000, Mexico
| | - Carlos R. Godínez-Reyes
- Cabo Pulmo National Park, Comisión Nacional de Áreas Naturales Protegidas, SEMARNAT, La Ribera, BCS, Mexico
| | - Karina Acevedo-Whitehouse
- Unit for Basic and Applied Microbiology, School of Natural Sciences, Autonomous University of Queretaro, Avenida de las Ciencias S/N, Queretaro 76230, Mexico
- The Marine Mammal Center, 2000 Bunker Road, Sausalito, CA 94965, USA
- Sea Lion Cancer Consortium. http://www.smru.st-andrews.ac.uk/slicc
- Author for correspondence: Karina Acevedo-Whitehouse e-mail:
| |
Collapse
|
33
|
Zhang Q, Kota KP, Alam SG, Nickerson JA, Dickinson RB, Lele TP. Coordinated Dynamics of RNA Splicing Speckles in the Nucleus. J Cell Physiol 2015; 231:1269-75. [PMID: 26496460 DOI: 10.1002/jcp.25224] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 10/21/2015] [Indexed: 12/28/2022]
Abstract
Despite being densely packed with chromatin, nuclear bodies and a nucleoskeletal network, the nucleus is a remarkably dynamic organelle. Chromatin loops form and relax, RNA transcripts and transcription factors move diffusively, and nuclear bodies move. We show here that RNA splicing speckled domains (splicing speckles) fluctuate in constrained nuclear volumes and remodel their shapes. Small speckles move in a directed way toward larger speckles with which they fuse. This directed movement is reduced upon decreasing cellular ATP levels or inhibiting RNA polymerase II activity. The random movement of speckles is reduced upon decreasing cellular ATP levels, moderately reduced after inhibition of SWI/SNF chromatin remodeling and modestly increased upon inhibiting RNA polymerase II activity. To define the paths through which speckles can translocate in the nucleus, we generated a pressure gradient to create flows in the nucleus. In response to the pressure gradient, speckles moved along curvilinear paths in the nucleus. Collectively, our results demonstrate a new type of ATP-dependent motion in the nucleus. We present a model where recycling splicing factors return as part of small sub-speckles from distal sites of RNA processing to larger splicing speckles by a directed ATP-driven mechanism through interchromatin spaces.
Collapse
Affiliation(s)
- Qiao Zhang
- Department of Chemical Engineering, University of Florida, Gainesville, Florida
| | - Krishna P Kota
- Department of Cellular and Tissue Imaging, Perkin Elmer Inc., Waltham, Massachusetts
| | - Samer G Alam
- Department of Chemical Engineering, University of Florida, Gainesville, Florida
| | - Jeffrey A Nickerson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Richard B Dickinson
- Department of Chemical Engineering, University of Florida, Gainesville, Florida
| | - Tanmay P Lele
- Department of Chemical Engineering, University of Florida, Gainesville, Florida
| |
Collapse
|
34
|
SWI/SNF complexes are required for full activation of the DNA-damage response. Oncotarget 2015; 6:732-45. [PMID: 25544751 PMCID: PMC4359251 DOI: 10.18632/oncotarget.2715] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Accepted: 11/09/2014] [Indexed: 01/09/2023] Open
Abstract
SWI/SNF complexes utilize BRG1 (also known as SMARCA4) or BRM (also known as SMARCA2) as alternative catalytic subunits with ATPase activity to remodel chromatin. These chromatin-remodeling complexes are required for mammalian development and are mutated in ~20% of all human primary tumors. Yet our knowledge of their tumor-suppressor mechanism is limited. To investigate the role of SWI/SNF complexes in the DNA-damage response (DDR), we used shRNAs to deplete BRG1 and BRM and then exposed these cells to a panel of 6 genotoxic agents. Compared to controls, the shRNA knockdown cells were hypersensitive to certain genotoxic agents that cause double-strand breaks (DSBs) associated with stalled/collapsed replication forks but not to ionizing radiation-induced DSBs that arise independently of DNA replication. These findings were supported by our analysis of DDR kinases, which demonstrated a more prominent role for SWI/SNF in the activation of the ATR-Chk1 pathway than the ATM-Chk2 pathway. Surprisingly, γH2AX induction was attenuated in shRNA knockdown cells exposed to a topoisomerase II inhibitor (etoposide) but not to other genotoxic agents including IR. However, this finding is compatible with recent studies linking SWI/SNF with TOP2A and TOP2BP1. Depletion of BRG1 and BRM did not result in genomic instability in a tumor-derived cell line but did result in nucleoplasmic bridges in normal human fibroblasts. Taken together, these results suggest that SWI/SNF tumor-suppressor activity involves a role in the DDR to attenuate replicative stress and genomic instability. These results may also help to inform the selection of chemotherapeutics for tumors deficient for SWI/SNF function.
Collapse
|
35
|
Wu Q, Madany P, Akech J, Dobson JR, Douthwright S, Browne G, Colby JL, Winter GE, Bradner JE, Pratap J, Sluder G, Bhargava R, Chiosea SI, van Wijnen AJ, Stein JL, Stein GS, Lian JB, Nickerson JA, Imbalzano AN. The SWI/SNF ATPases Are Required for Triple Negative Breast Cancer Cell Proliferation. J Cell Physiol 2015; 230:2683-94. [PMID: 25808524 DOI: 10.1002/jcp.24991] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 03/18/2015] [Indexed: 12/30/2022]
Abstract
The Brahma (BRM) and Brahma-related Gene 1 (BRG1) ATPases are highly conserved homologs that catalyze the chromatin remodeling functions of the multi-subunit human SWI/SNF chromatin remodeling enzymes in a mutually exclusive manner. SWI/SNF enzyme subunits are mutated or missing in many cancer types, but are overexpressed without apparent mutation in other cancers. Here, we report that both BRG1 and BRM are overexpressed in most primary breast cancers independent of the tumor's receptor status. Knockdown of either ATPase in a triple negative breast cancer cell line reduced tumor formation in vivo and cell proliferation in vitro. Fewer cells in S phase and an extended cell cycle progression time were observed without any indication of apoptosis, senescence, or alterations in migration or attachment properties. Combined knockdown of BRM and BRG1 showed additive effects in the reduction of cell proliferation and time required for completion of cell cycle, suggesting that these enzymes promote cell cycle progression through independent mechanisms. Knockout of BRG1 or BRM using CRISPR/Cas9 technology resulted in the loss of viability, consistent with a requirement for both enzymes in triple negative breast cancer cells.
Collapse
Affiliation(s)
- Qiong Wu
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Pasil Madany
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Jacqueline Akech
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Jason R Dobson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Molecular Biology, Cell Biology and Biochemistry, Center for Computational Molecular Biology, Brown University, Providence, Rhode Island
- Department of Computer Science, Brown University, Providence, Rhode Island
| | - Stephen Douthwright
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Gillian Browne
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, Vermont
| | - Jennifer L Colby
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Georg E Winter
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
| | - James E Bradner
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts
- Department of Medicine, Harvard Medical School, Boston, Massachusetts
| | - Jitesh Pratap
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Anatomy and Cell Biology, Rush University, Chicago, Illinois
| | - Greenfield Sluder
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Rohit Bhargava
- Department of Pathology, Magee-Womens Hospital, Pittsburgh, Pennsylvania
| | - Simion I Chiosea
- Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania
| | - Andre J van Wijnen
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Departments of Orthopedic Surgery & Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota
| | - Janet L Stein
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, Vermont
| | - Gary S Stein
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, Vermont
| | - Jane B Lian
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
- Department of Biochemistry and Vermont Cancer Center for Basic and Translational Research, University of Vermont College of Medicine, Burlington, Vermont
- Department of Orthopedics and Physical Rehabilitation, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Jeffrey A Nickerson
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Anthony N Imbalzano
- Department of Cell and Developmental Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| |
Collapse
|
36
|
Babahosseini H, Carmichael B, Strobl JS, Mahmoodi SN, Agah M. Sub-cellular force microscopy in single normal and cancer cells. Biochem Biophys Res Commun 2015; 463:587-92. [PMID: 26036579 DOI: 10.1016/j.bbrc.2015.05.100] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 05/28/2015] [Indexed: 01/26/2023]
Abstract
This work investigates the biomechanical properties of sub-cellular structures of breast cells using atomic force microscopy (AFM). The cells are modeled as a triple-layered structure where the Generalized Maxwell model is applied to experimental data from AFM stress-relaxation tests to extract the elastic modulus, the apparent viscosity, and the relaxation time of sub-cellular structures. The triple-layered modeling results allow for determination and comparison of the biomechanical properties of the three major sub-cellular structures between normal and cancerous cells: the up plasma membrane/actin cortex, the mid cytoplasm/nucleus, and the low nuclear/integrin sub-domains. The results reveal that the sub-domains become stiffer and significantly more viscous with depth, regardless of cell type. In addition, there is a decreasing trend in the average elastic modulus and apparent viscosity of the all corresponding sub-cellular structures from normal to cancerous cells, which becomes most remarkable in the deeper sub-domain. The presented modeling in this work constitutes a unique AFM-based experimental framework to study the biomechanics of sub-cellular structures.
Collapse
Affiliation(s)
- H Babahosseini
- VT MEMS Laboratory, The Bradley Department of Electrical and Computer Engineering, Blacksburg, VA 24061, USA
| | - B Carmichael
- Nonlinear Intelligent Structures Laboratory, Department of Mechanical Engineering, University of Alabama, Tuscaloosa, AL 35487-0276, USA
| | - J S Strobl
- VT MEMS Laboratory, The Bradley Department of Electrical and Computer Engineering, Blacksburg, VA 24061, USA
| | - S N Mahmoodi
- Nonlinear Intelligent Structures Laboratory, Department of Mechanical Engineering, University of Alabama, Tuscaloosa, AL 35487-0276, USA.
| | - M Agah
- VT MEMS Laboratory, The Bradley Department of Electrical and Computer Engineering, Blacksburg, VA 24061, USA.
| |
Collapse
|
37
|
Nikonenko AG, Bozhok YM. Simple computational technique to quantify nuclear shape asymmetry. Cytometry A 2014; 87:309-14. [DOI: 10.1002/cyto.a.22612] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 10/17/2014] [Accepted: 12/02/2014] [Indexed: 12/18/2022]
Affiliation(s)
| | - Yuriy M. Bozhok
- Department of Functional Diagnostics; Institute of Endocrinology and Metabolism; Kiev Ukraine
| |
Collapse
|
38
|
Rodríguez R, Hernández-Hernández O, Magaña JJ, González-Ramírez R, García-López ES, Cisneros B. Altered nuclear structure in myotonic dystrophy type 1-derived fibroblasts. Mol Biol Rep 2014; 42:479-88. [PMID: 25307018 DOI: 10.1007/s11033-014-3791-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 10/03/2014] [Indexed: 12/14/2022]
Abstract
Myotonic dystrophy type 1 (DM1) is a multisystem genetic disorder caused by a triplet nucleotide repeat expansion in the 3' untranslated region of the Dystrophia Myotonica-Protein Kinase (DMPK) gene. DMPK gene transcripts containing CUG expanded repeats accumulate in nuclear foci and ultimately cause altered splicing/gene expression of numerous secondary genes. The study of primary cell cultures derived from patients with DM1 has allowed the identification and further characterization of molecular mechanisms underlying the pathology in the natural context of the disease. In this study we show for the first time impaired nuclear structure in fibroblasts of DM1 patients. DM1-derived fibroblasts exhibited altered localization of the nuclear envelope (NE) proteins emerin and lamins A/C and B1 with concomitant increased size and altered shape of nuclei. Abnormal NE organization is more common in DM1 fibroblasts containing abundant nuclear foci, implying expression of the expanded RNA as determinant of nuclear defects. That transient expression of the DMPK 3' UTR containing 960 CTG but not with the 3' UTR lacking CTG repeats is sufficient to generate NE disruption in normal fibroblasts confirms the direct impact of mutant RNA on NE architecture. We also evidence nucleoli distortion in DM1 fibroblasts by immunostaining of the nucleolar protein fibrillarin, implying a broader effect of the mutant RNA on nuclear structure. In summary, these findings reveal that NE disruption, a hallmark of laminopathy disorders, is a novel characteristic of DM1.
Collapse
Affiliation(s)
- R Rodríguez
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Av. IPN 2508 Col Zacatenco, 07360, Mexico, D.F, Mexico
| | | | | | | | | | | |
Collapse
|
39
|
Chiotaki R, Polioudaki H, Theodoropoulos PA. Differential nuclear shape dynamics of invasive andnon-invasive breast cancer cells are associated with actin cytoskeleton organization and stability. Biochem Cell Biol 2014; 92:287-95. [PMID: 25053513 DOI: 10.1139/bcb-2013-0120] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cancer cells often exhibit characteristic aberrations in their nuclear architecture, which are indicative of their malignant potential. In this study, we have examined the nuclear and cytoskeletal composition, attachment configuration dynamics, and osmotic or drug treatment response of invasive (Hs578T and MDA-MB-231) and non-invasive (MCF-10A and MCF-7) breast cancer cell lines. Unlike MCF-10A and MCF-7, Hs578T and MDA-MB-231 cells showed extensive nuclear elasticity and deformability and displayed distinct kinetic profiles during substrate attachment. The nuclear shape of MCF-10A and MCF-7 cells remained almost unaffected upon detachment, hyperosmotic shock, or cytoskeleton depolymerization, while Hs578T and MDA-MB-231 revealed dramatic nuclear contour malformations following actin reorganization.
Collapse
Affiliation(s)
- Rena Chiotaki
- Department of Biochemistry, School of Medicine, University of Crete, Heraklion 71003, Greece
| | | | | |
Collapse
|
40
|
Sizing and shaping the nucleus: mechanisms and significance. Curr Opin Cell Biol 2014; 28:16-27. [PMID: 24503411 DOI: 10.1016/j.ceb.2014.01.003] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Revised: 01/07/2014] [Accepted: 01/11/2014] [Indexed: 01/14/2023]
Abstract
The size and shape of the nucleus are tightly regulated, indicating the physiological significance of proper nuclear morphology, yet the mechanisms and functions of nuclear size and shape regulation remain poorly understood. Correlations between altered nuclear morphology and certain disease states have long been observed, most notably many cancers are diagnosed and staged based on graded increases in nuclear size. Here we review recent studies investigating the mechanisms regulating nuclear size and shape, how mitotic events influence nuclear morphology, and the role of nuclear size and shape in subnuclear chromatin organization and cancer progression.
Collapse
|
41
|
Nuclear morphometry, epigenetic changes, and clinical relevance in prostate cancer. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2013; 773:77-99. [PMID: 24563344 PMCID: PMC7123969 DOI: 10.1007/978-1-4899-8032-8_4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Nuclear structure alterations in cancer involve global genetic (mutations, amplifications, copy number variations, translocations, etc.) and epigenetic (DNA methylation and histone modifications) events that dramatically and dynamically spatially change chromatin, nuclear body, and chromosome organization. In prostate cancer (CaP) there appears to be early (<50 years) versus late (>60 years) onset clinically significant cancers, and we have yet to clearly understand the hereditary and somatic-based molecular pathways involved. We do know that once cancer is initiated, dedifferentiation of the prostate gland occurs with significant changes in nuclear structure driven by numerous genetic and epigenetic processes. This review focuses upon the nuclear architecture and epigenetic dynamics with potential translational clinically relevant applications to CaP. Further, the review correlates changes in the cancer-driven epigenetic process at the molecular level and correlates these alterations to nuclear morphological quantitative measurements. Finally, we address how we can best utilize this knowledge to improve the efficacy of personalized treatment of cancer.
Collapse
|
42
|
Skarp KP, Huet G, Vartiainen MK. Steady-state nuclear actin levels are determined by export competent actin pool. Cytoskeleton (Hoboken) 2013; 70:623-34. [PMID: 23749625 DOI: 10.1002/cm.21116] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Revised: 05/22/2013] [Accepted: 05/23/2013] [Indexed: 12/18/2022]
Abstract
A number of studies in the last decade have irrevocably promoted actin into a fully fledged member of the nuclear compartment, where it, among other crucial tasks, facilitates transcription and chromatin remodeling. Changes in nuclear actin levels have been linked to different cellular processes: decreased nuclear actin to quiescence and increased nuclear actin to differentiation. Importin 9 and exportin 6 transport factors are responsible for the continuous nucleocytoplasmic shuttling of actin, but the mechanisms, which result in modulated actin levels, have not been characterized. We find that in cells growing under normal growth conditions, the levels of nuclear actin vary considerably from cell to cell. To understand the basis for this, we have extensively quantified several cellular parameters while at the same time recording the import and export rates of green fluorescent protein (GFP)-tagged actin. Surprisingly, our dataset shows that the ratio of nuclear to cytoplasmic fluorescence intensity, but not nuclear shape, size, cytoplasm size, or their ratio, correlates negatively with both import and export rate of actin. This suggests that high-nuclear actin content is maintained by both diminished import and export. The high nuclear actin containing cells still show high mobility of actin, but it is not export competent, suggesting increased binding of actin to nuclear complexes. Creation of such export incompetent actin pool would ensure enough actin is retained in the nucleus and make it available for the various nuclear functions described for actin.
Collapse
Affiliation(s)
- Kari-Pekka Skarp
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, Viikinkaari 9, 00014, Helsinki, Finland
| | | | | |
Collapse
|
43
|
Imbalzano AN, Imbalzano KM, Nickerson JA. BRG1, a SWI/SNF chromatin remodeling enzyme ATPase, is required for maintenance of nuclear shape and integrity. Commun Integr Biol 2013; 6:e25153. [PMID: 24228137 PMCID: PMC3821668 DOI: 10.4161/cib.25153] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 05/23/2013] [Indexed: 01/11/2023] Open
Abstract
We recently reported that reducing the levels of BRG1, the catalytic subunit of mammalian SWI/SNF chromatin remodeling enzymes, induces alterations in nuclear shape in a breast epithelial cell line. Immunostaining the BRG1 knockdown cells with nuclear lamina antibodies revealed a significantly increased frequency of grooves, or invaginations, in the nuclei. Disruption of each of the major cytoplasmic filament systems (actin, tubulin and cytokeratins) had no impact on the BRG1-dependent changes in nuclear shape, indicating that the observed changes in nuclear morphology are unlikely to be a result of alterations in the integrity of the nuclear-cytoplamic contacts in the cell. We propose that the BRG1-dependent nuclear shape changes reflect a role for the chromatin remodeling enzyme in maintaining the structural integrity of the nucleus via global regulation of chromatin structure and dynamics within the nucleus.
Collapse
Affiliation(s)
- Anthony N Imbalzano
- Department of Cell and Developmental Biology; University of Massachusetts Medical School; Worcester, MA USA
| | | | | |
Collapse
|