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Fernandez MK, Sinha M, Zidan M, Renz M. Nuclear actin filaments - a historical perspective. Nucleus 2024; 15:2320656. [PMID: 38384139 PMCID: PMC10885181 DOI: 10.1080/19491034.2024.2320656] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2023] [Accepted: 02/14/2024] [Indexed: 02/23/2024] Open
Abstract
The view on nuclear filaments formed by non-skeletal β-actin has significantly changed over the decades. Initially, filamentous actin was observed in amphibian oocyte nuclei and only under specific cell stress conditions in mammalian cell nuclei. Improved labeling and imaging technologies have permitted insights into a transient but microscopically apparent filament network that is relevant for chromatin organization, biomechanics of the mammalian cell nucleus, gene expression, and DNA damage repair. Here, we will provide a historical perspective on the developing insight into nuclear actin filaments.
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Affiliation(s)
| | - Molika Sinha
- Gynecologic Oncology Division, School of Medicine Stanford University, Palo Alto, CA, USA
| | - Mia Zidan
- Gynecologic Oncology Division, School of Medicine Stanford University, Palo Alto, CA, USA
| | - Malte Renz
- Gynecologic Oncology Division, School of Medicine Stanford University, Palo Alto, CA, USA
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2
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Mokin YI, Povarova OI, Antifeeva IA, Artemov AV, Uversky VN, Turoverov KK, Kuznetsova IM, Fonin AV. Bioinformatics Analysis of Actin Interactome: Characterization of the Nuclear and Cytoplasmic Actin-Binding Proteins. Protein J 2024; 43:675-682. [PMID: 38824467 DOI: 10.1007/s10930-024-10207-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/09/2024] [Indexed: 06/03/2024]
Abstract
Actin is present in the cytoplasm and nucleus of every eukaryotic cell. In the cytoplasm, framework and motor functions of actin are associated with its ability to polymerize to form F-actin. In the nucleus, globular actin plays a significant functional role. For a globular protein, actin has a uniquely large number of proteins with which it interacts. Bioinformatics analysis of the actin interactome showed that only a part of actin-binding proteins are both cytoplasmic and nuclear. There are proteins that interact only with cytoplasmic, or only with nuclear actin. The first pool includes proteins associated with the formation, regulation, and functioning of the actin cytoskeleton predominate, while nuclear actin-binding proteins are involved in the majority of key nuclear processes, from regulation of transcription to DNA damage response. Bioinformatics analysis of the structure of actin-binding proteins showed that these are mainly intrinsically disordered proteins, many of which are part of membrane-less organelles. Interestingly, although the number of intrinsically disordered actin-binding proteins in the nucleus is greater than in the cytoplasm, the drivers for the formation of the membrane-less organelles in the cytoplasm are significantly (four times) greater than in the nucleus.
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Affiliation(s)
- Yakov I Mokin
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russian Federation
| | - Olga I Povarova
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russian Federation
| | - Iuliia A Antifeeva
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russian Federation
| | - Alexey V Artemov
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russian Federation
| | - Vladimir N Uversky
- Department of Molecular Medicine, Morsani College of Medicine, USF Health Byrd Alzheimer's Research Institute, University of South Florida, 12901 Bruce B. Downs Blvd., MDC07, Tampa, FL, 33612, USA.
| | - Konstantin K Turoverov
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russian Federation
| | - Irina M Kuznetsova
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russian Federation.
| | - Alexander V Fonin
- Laboratory of Structural Dynamics, Stability and Folding of Proteins, Institute of Cytology, Russian Academy of Sciences, St. Petersburg, 194064, Russian Federation.
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3
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Tamura I, Miyamoto K, Hatanaka C, Shiroshita A, Fujimura T, Shirafuta Y, Mihara Y, Maekawa R, Taketani T, Sato S, Matsumoto K, Tamura H, Sugino N. Nuclear actin assembly is an integral part of decidualization in human endometrial stromal cells. Commun Biol 2024; 7:830. [PMID: 38992143 PMCID: PMC11239864 DOI: 10.1038/s42003-024-06492-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Accepted: 06/21/2024] [Indexed: 07/13/2024] Open
Abstract
Decidualization of the human endometrium is critical for establishing pregnancy and is entailed by differentiation of endometrial stromal cells (ESCs) into decidual cells. During decidualization, the actin cytoskeleton is dynamically reorganized for the ESCs' morphological and functional changes. Although actin dynamically alters its polymerized state upon external stimuli not only in the cytoplasm, but also in the nucleus, nuclear actin dynamics during decidualization have not been elucidated. Here, we show that nuclear actin was specifically assembled during decidualization of human ESCs. This decidualization-specific formation of nuclear actin filaments was disassembled following the withdrawal of the decidualization stimulus, suggesting its reversible process. Mechanistically, RNA-seq analyses revealed that the forced disassembly of nuclear actin resulted in the suppression of decidualization, accompanied with the abnormal upregulation of cell proliferation genes, leading to incomplete cell cycle arrest. CCAAT/enhancer-binding protein beta (C/EBPβ), an important regulator for decidualization, was responsible for downregulation of the nuclear actin exporter, thus accelerating nuclear actin accumulation and its assembly for decidualization. Taken together, we demonstrate that decidualization-specific nuclear actin assembly induces cell cycle arrest for establishing the decidualized state of ESCs. We propose that not only the cytoplasmic actin, but also nuclear actin dynamics profoundly affect decidualization process in humans for ensuring pregnancy.
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Affiliation(s)
- Isao Tamura
- Department of Obstetrics and Gynecology, Yamaguchi University Graduate School of Medicine, Minamikogushi 1-1-1, Ube, 755-8505, Japan.
| | - Kei Miyamoto
- Laboratory of Molecular Developmental Biology, Faculty of Biology-Oriented Science and Technology, Kindai University, Wakayama, 649-6493, Japan.
- Laboratory of Animal Reproductive Physiology, Faculty of Agriculture, Kyushu University, Fukuoka, 819-0395, Japan.
| | - Chiharu Hatanaka
- Department of Obstetrics and Gynecology, Yamaguchi University Graduate School of Medicine, Minamikogushi 1-1-1, Ube, 755-8505, Japan
| | - Amon Shiroshita
- Department of Obstetrics and Gynecology, Yamaguchi University Graduate School of Medicine, Minamikogushi 1-1-1, Ube, 755-8505, Japan
| | - Taishi Fujimura
- Department of Obstetrics and Gynecology, Yamaguchi University Graduate School of Medicine, Minamikogushi 1-1-1, Ube, 755-8505, Japan
| | - Yuichiro Shirafuta
- Department of Obstetrics and Gynecology, Yamaguchi University Graduate School of Medicine, Minamikogushi 1-1-1, Ube, 755-8505, Japan
| | - Yumiko Mihara
- Department of Obstetrics and Gynecology, Yamaguchi University Graduate School of Medicine, Minamikogushi 1-1-1, Ube, 755-8505, Japan
| | - Ryo Maekawa
- Department of Obstetrics and Gynecology, Yamaguchi University Graduate School of Medicine, Minamikogushi 1-1-1, Ube, 755-8505, Japan
| | - Toshiaki Taketani
- Department of Obstetrics and Gynecology, Yamaguchi University Graduate School of Medicine, Minamikogushi 1-1-1, Ube, 755-8505, Japan
| | - Shun Sato
- Department of Obstetrics and Gynecology, Yamaguchi University Graduate School of Medicine, Minamikogushi 1-1-1, Ube, 755-8505, Japan
| | - Kazuya Matsumoto
- Laboratory of Molecular Developmental Biology, Faculty of Biology-Oriented Science and Technology, Kindai University, Wakayama, 649-6493, Japan
| | - Hiroshi Tamura
- Department of Obstetrics and Gynecology, Yamaguchi University Graduate School of Medicine, Minamikogushi 1-1-1, Ube, 755-8505, Japan
| | - Norihiro Sugino
- Department of Obstetrics and Gynecology, Yamaguchi University Graduate School of Medicine, Minamikogushi 1-1-1, Ube, 755-8505, Japan
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Kyheröinen S, Prajapati B, Sokolova M, Schmitz M, Viita T, Geyer M, Vartiainen MK. Actin associates with actively elongating genes and binds directly to the Cdk9 subunit of P-TEFb. J Biol Chem 2024; 300:105698. [PMID: 38301887 PMCID: PMC10891344 DOI: 10.1016/j.jbc.2024.105698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 01/08/2024] [Accepted: 01/21/2024] [Indexed: 02/03/2024] Open
Abstract
Nuclear actin has been demonstrated to be essential for optimal transcription, but the molecular mechanisms and direct binding partner for actin in the RNA polymerase complex have remained unknown. By using purified proteins in a variety of biochemical assays, we demonstrate a direct and specific interaction between monomeric actin and Cdk9, the kinase subunit of the positive transcription elongation factor b required for RNA polymerase II pause-release. This interaction efficiently prevents actin polymerization, is not dependent on kinase activity of Cdk9, and is not involved with releasing positive transcription elongation factor b from its inhibitor 7SK snRNP complex. Supporting the specific role for actin in the elongation phase of transcription, chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) reveals that actin interacts with genes only upon their active transcription elongation. This study therefore provides novel insights into the mechanisms by which actin facilitates the transcription process.
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Affiliation(s)
- Salla Kyheröinen
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Bina Prajapati
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Maria Sokolova
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | | | - Tiina Viita
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Matthias Geyer
- Institute of Structural Biology, University of Bonn, Bonn, Germany
| | - Maria K Vartiainen
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland.
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Stephan OOH. Effects of environmental stress factors on the actin cytoskeleton of fungi and plants: Ionizing radiation and ROS. Cytoskeleton (Hoboken) 2023; 80:330-355. [PMID: 37066976 DOI: 10.1002/cm.21758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 03/20/2023] [Accepted: 03/29/2023] [Indexed: 04/18/2023]
Abstract
Actin is an abundant and multifaceted protein in eukaryotic cells that has been detected in the cytoplasm as well as in the nucleus. In cooperation with numerous interacting accessory-proteins, monomeric actin (G-actin) polymerizes into microfilaments (F-actin) which constitute ubiquitous subcellular higher order structures. Considering the extensive spatial dimensions and multifunctionality of actin superarrays, the present study analyses the issue if and to what extent environmental stress factors, specifically ionizing radiation (IR) and reactive oxygen species (ROS), affect the cellular actin-entity. In that context, this review particularly surveys IR-response of fungi and plants. It examines in detail which actin-related cellular constituents and molecular pathways are influenced by IR and related ROS. This comprehensive survey concludes that the general integrity of the total cellular actin cytoskeleton is a requirement for IR-tolerance. Actin's functions in genome organization and nuclear events like chromatin remodeling, DNA-repair, and transcription play a key role. Beyond that, it is highly significant that the macromolecular cytoplasmic and cortical actin-frameworks are affected by IR as well. In response to IR, actin-filament bundling proteins (fimbrins) are required to stabilize cables or patches. In addition, the actin-associated factors mediating cellular polarity are essential for IR-survivability. Moreover, it is concluded that a cellular homeostasis system comprising ROS, ROS-scavengers, NADPH-oxidases, and the actin cytoskeleton plays an essential role here. Consequently, besides the actin-fraction which controls crucial genome-integrity, also the portion which facilitates orderly cellular transport and polarized growth has to be maintained in order to survive IR.
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Affiliation(s)
- Octavian O H Stephan
- Department of Biology, Friedrich-Alexander University of Erlangen-Nuremberg, Erlangen, Bavaria, 91058, Germany
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6
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Rubio LS, Gross DS. Dynamic coalescence of yeast Heat Shock Protein genes bypasses the requirement for actin. Genetics 2023; 223:iyad006. [PMID: 36659814 PMCID: PMC10319981 DOI: 10.1093/genetics/iyad006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 07/22/2022] [Accepted: 01/03/2023] [Indexed: 01/21/2023] Open
Abstract
Nuclear actin has been implicated in dynamic chromatin rearrangements in diverse eukaryotes. In mammalian cells, it is required to reposition double-strand DNA breaks to enable homologous recombination repair and to enhance transcription by facilitating RNA Pol II recruitment to gene promoters. In the yeast Saccharomyces cerevisiae, nuclear actin modulates interphase chromosome dynamics and is required to reposition the induced INO1 gene to the nuclear periphery. Here, we have investigated the role of actin in driving intergenic interactions between Heat Shock Factor 1 (Hsf1)-regulated Heat Shock Protein (HSP) genes in budding yeast. These genes, dispersed on multiple chromosomes, dramatically reposition following exposure of cells to acute thermal stress, leading to their clustering within dynamic biomolecular condensates. Using an auxin-induced degradation strategy, we found that conditional depletion of nucleators of either linear or branched F-actin (Bni1/Bnr1 and Arp2, respectively) had little or no effect on heat shock-induced HSP gene coalescence or transcription. In addition, we found that pretreatment of cells with latrunculin A, an inhibitor of both filamentous and monomeric actin, failed to affect intergenic interactions between activated HSP genes and their heat shock-induced intragenic looping and folding. Moreover, latrunculin A pretreatment had little effect on HSP gene expression at either RNA or protein levels. In notable contrast, we confirmed that repositioning of activated INO1 to the nuclear periphery and its proper expression do require actin. Collectively, our work suggests that transcriptional activation and 3D genome restructuring of thermally induced, Hsf1-regulated genes can occur in the absence of actin.
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Affiliation(s)
- Linda S Rubio
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA
| | - David S Gross
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA
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7
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Actin dynamics in protein homeostasis. Biosci Rep 2022; 42:231720. [PMID: 36043949 PMCID: PMC9469105 DOI: 10.1042/bsr20210848] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/22/2022] [Accepted: 08/31/2022] [Indexed: 11/17/2022] Open
Abstract
Cell homeostasis is maintained in all organisms by the constant adjustment of cell constituents and organisation to account for environmental context. Fine-tuning of the optimal balance of proteins for the conditions, or protein homeostasis, is critical to maintaining cell homeostasis. Actin, a major constituent of the cytoskeleton, forms many different structures which are acutely sensitive to the cell environment. Furthermore, actin structures interact with and are critically important for the function and regulation of multiple factors involved with mRNA and protein production and degradation, and protein regulation. Altogether, actin is a key, if often overlooked, regulator of protein homeostasis across eukaryotes. In this review, we highlight these roles and how they are altered following cell stress, from mRNA transcription to protein degradation.
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Mishra S, Levy DL. Nuclear F-actin and Lamin A antagonistically modulate nuclear shape. J Cell Sci 2022; 135:275607. [PMID: 35665815 PMCID: PMC9377710 DOI: 10.1242/jcs.259692] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Accepted: 05/28/2022] [Indexed: 12/25/2022] Open
Abstract
Nuclear shape influences cell migration, gene expression and cell cycle progression, and is altered in disease states like laminopathies and cancer. What factors and forces determine nuclear shape? We find that nuclei assembled in Xenopus egg extracts in the presence of dynamic F-actin exhibit a striking bilobed nuclear morphology with distinct membrane compositions in the two lobes and accumulation of F-actin at the inner nuclear envelope. The addition of Lamin A (encoded by lmna), which is absent from Xenopus eggs, results in rounder nuclei, suggesting that opposing nuclear F-actin and Lamin A forces contribute to the regulation of nuclear shape. Nuclear F-actin also promotes altered nuclear shape in Lamin A-knockdown HeLa cells and, in both systems, abnormal nuclear shape is driven by formins and not Arp2/3 or myosin. Although the underlying mechanisms might differ in Xenopus and HeLa cells, we propose that nuclear F-actin filaments nucleated by formins impart outward forces that lead to altered nuclear morphology unless Lamin A is present. Targeting nuclear actin dynamics might represent a novel approach to rescuing disease-associated defects in nuclear shape.
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Affiliation(s)
- Sampada Mishra
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Daniel L. Levy
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA,Author for correspondence ()
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Bishnupuri KS, Sainathan SK, Ciorba MA, Houchen CW, Dieckgraefe BK. Reg4 Interacts with CD44 to Regulate Proliferation and Stemness of Colorectal and Pancreatic Cancer Cells. Mol Cancer Res 2022; 20:387-399. [PMID: 34753802 DOI: 10.1158/1541-7786.mcr-21-0224] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 09/08/2021] [Accepted: 11/01/2021] [Indexed: 11/16/2022]
Abstract
Regenerating Gene 4 (Reg4) is highly upregulated in gastrointestinal (GI) malignancies including colorectal and pancreatic cancers. Numerous studies demonstrated an association between higher Reg4 expression and tumor aggressiveness, intrinsic resistance to apoptotic death, and poor outcomes from GI malignancies. However, the precise receptor and underlying signaling mechanism have remained unknown. Although we previously reported a Reg4-mediated induction of EGFR activity in colorectal cancer cells, a direct interaction between Reg4 and EGFR was not observed. This study is focused on identifying the cell surface binding partner of Reg4 and dissecting its role in colorectal cancer and pancreatic cancer growth and stem cell survival. In vitro models of human colorectal cancer and pancreatic cancer were used to evaluate the results. Results of this study find: (i) Reg4 interacts with CD44, a transmembrane protein expressed by a population of colorectal cancer and pancreatic cancer cells; (ii) Reg4 activates regulated intramembrane proteolysis of CD44 resulting in γ-secretase-mediated cleavage and release of the CD44 intracytoplasmic domain (CD44ICD) that functions as a transcriptional activator of D-type cyclins involved in the regulation of cancer cell proliferation and Klf4 and Sox2 expression involved in regulating pluripotency of cancer stem cells; and (iii) Reg4 significantly increases colorectal cancer and pancreatic cancer cell proliferation and their clonogenic potential in stem cell assays. IMPLICATIONS These results suggest that pro-proliferative and pro-stemness effects of Reg4 are mediated through γ-secretase-mediated CD44/CD44ICD signaling, hence strategies to disrupt Reg4-CD44-γ-secretase-CD44ICD signaling axis may increase cancer cell susceptibility to chemo- and radiotherapeutics.
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Affiliation(s)
- Kumar S Bishnupuri
- Division of Gastroenterology, Washington University School of Medicine, St Louis, Missouri
- Veteran Affair St Louis Health Care System, St Louis, Missouri
| | - Satheesh K Sainathan
- Division of Gastroenterology, Washington University School of Medicine, St Louis, Missouri
| | - Matthew A Ciorba
- Division of Gastroenterology, Washington University School of Medicine, St Louis, Missouri
| | - Courtney W Houchen
- Section of Digestive Disease and Nutrition, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma
| | - Brian K Dieckgraefe
- Division of Gastroenterology, Washington University School of Medicine, St Louis, Missouri
- Veteran Affair St Louis Health Care System, St Louis, Missouri
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Salatino A, Mirabelli M, Chiefari E, Greco M, Di Vito A, Bonapace G, Brunetti FS, Crocerossa F, Epstein AL, Foti DP, Brunetti A. The anticancer effects of Metformin in the male germ tumor SEM-1 cell line are mediated by HMGA1. Front Endocrinol (Lausanne) 2022; 13:1051988. [PMID: 36506071 PMCID: PMC9727077 DOI: 10.3389/fendo.2022.1051988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Accepted: 11/09/2022] [Indexed: 11/24/2022] Open
Abstract
INTRODUCTION Germ cell tumors (GCTs) are the most common type of cancer in young men. These tumors usually originate from the testis, but they can occasionally develop from extragonadal sites probably due to primordial germ cells (PGCs) migration errors. Cisplatin-based chemotherapy is usually effective for male GCTs, but the risk of toxicity is high and new therapeutic strategies are needed. Although Metformin (Met) has been widely studied as a potential cancer treatment over the past decades, there is limited evidence to support its use in treating male GCTs. Additionally, the mechanism by which it acts on tumor cells is still not entirely understood. METHODS SEM-1 cells, a newly established human cell line of extragonadal origin, were treated with Met. Cell viability was studied by MTT assay, while cell migration and invasion were studied by the wound healing assay and the transwell assay, respectively. The effect of Met on 3D spheroid formation was determined by seeding SEM-1 cells in appropriate cell suspension culture conditions, and cell cycle was characterized by flow cytometry. Factors involved in PGCs migration and GCT invasion, such as IGFBP1, IGF1R, MMP-11 and c-Kit, together with cyclin D1 (a key regulator of cell cycle progression), and the upstream factor, HMGA1, were determined by immunoblots. RESULTS Treatment of SEM-1 cells with Met resulted in a potent and dose-dependent reduction of cell proliferation, as evidenced by decreased nuclear abundance of cyclin D1 and cell cycle arrest in G1 phase. Also, Met prevented the formation of 3D spheroids, and blocked cell migration and invasion by reducing the expression of IGFBP1, IGF1R and MMP-11. Both, IGFBP1 and MMP-11 are under control of HMGA1, a chromatin-associated protein that is involved in the regulation of important oncogenic, metabolic and embryological processes. Intriguingly, an early reduction in the nuclear abundance of HMGA1 occurred in SEM-1 cells treated with Met. CONCLUSIONS Our results document the antiproliferative and antimigratory effects of Met in SEM-1 cells, providing new insights into the potential treatments for male GCTs. The anticancer properties of Met in SEM-1 cells are likely related to its ability to interfere with HMGA1 and downstream targets, including cyclin D1, the IGFs system, and MMP-11.
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Affiliation(s)
- Alessandro Salatino
- Department of Health Sciences, University “Magna Græcia” of Catanzaro, Catanzaro, Italy
| | - Maria Mirabelli
- Department of Health Sciences, University “Magna Græcia” of Catanzaro, Catanzaro, Italy
| | - Eusebio Chiefari
- Department of Health Sciences, University “Magna Græcia” of Catanzaro, Catanzaro, Italy
| | - Marta Greco
- Department of Health Sciences, University “Magna Græcia” of Catanzaro, Catanzaro, Italy
| | - Anna Di Vito
- Department of Experimental and Clinical Medicine, University “Magna Græcia” of Catanzaro, Catanzaro, Italy
| | - Giuseppe Bonapace
- Department of Medical and Surgical Sciences, University “Magna Græcia” of Catanzaro, Catanzaro, Italy
| | - Francesco S. Brunetti
- Department of Health Sciences, University “Magna Græcia” of Catanzaro, Catanzaro, Italy
| | - Fabio Crocerossa
- Department of Experimental and Clinical Medicine, University “Magna Græcia” of Catanzaro, Catanzaro, Italy
| | - Alan L. Epstein
- Department of Pathology, USC Keck School of Medicine, Los Angeles, CA, United States
| | - Daniela P. Foti
- Department of Experimental and Clinical Medicine, University “Magna Græcia” of Catanzaro, Catanzaro, Italy
| | - Antonio Brunetti
- Department of Health Sciences, University “Magna Græcia” of Catanzaro, Catanzaro, Italy
- *Correspondence: Antonio Brunetti,
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11
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Rapid ensemble measurement of protein diffusion and probe blinking dynamics in cells. BIOPHYSICAL REPORTS 2021; 1:100015. [PMID: 36425455 PMCID: PMC9680803 DOI: 10.1016/j.bpr.2021.100015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 08/30/2021] [Indexed: 12/25/2022]
Abstract
We present a fluorescence fluctuation image correlation analysis method that can rapidly and simultaneously measure the diffusion coefficient, photoblinking rates, and fraction of diffusing particles of fluorescent molecules in cells. Unlike other image correlation techniques, we demonstrated that our method could be applied irrespective of a nonuniformly distributed, immobile blinking fluorophore population. This allows us to measure blinking and transport dynamics in complex cell morphologies, a benefit for a range of super-resolution fluorescence imaging approaches that rely on probe emission blinking. Furthermore, we showed that our technique could be applied without directly accounting for photobleaching. We successfully employed our technique on several simulations with realistic EMCCD noise and photobleaching models, as well as on Dronpa-C12-labeled β-actin in living NIH/3T3 and HeLa cells. We found that the diffusion coefficients measured using our method were consistent with previous literature values. We further found that photoblinking rates measured in the live HeLa cells varied as expected with changing excitation power.
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12
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The Role of Emerin in Cancer Progression and Metastasis. Int J Mol Sci 2021; 22:ijms222011289. [PMID: 34681951 PMCID: PMC8537873 DOI: 10.3390/ijms222011289] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 10/14/2021] [Accepted: 10/15/2021] [Indexed: 12/27/2022] Open
Abstract
It is commonly recognized in the field that cancer cells exhibit changes in the size and shape of their nuclei. These features often serve as important biomarkers in the diagnosis and prognosis of cancer patients. Nuclear size can significantly impact cell migration due to its incredibly large size. Nuclear structural changes are predicted to regulate cancer cell migration. Nuclear abnormalities are common across a vast spectrum of cancer types, regardless of tissue source, mutational spectrum, and signaling dependencies. The pervasiveness of nuclear alterations suggests that changes in nuclear structure may be crucially linked to the transformation process. The factors driving these nuclear abnormalities, and the functional consequences, are not completely understood. Nuclear envelope proteins play an important role in regulating nuclear size and structure in cancer. Altered expression of nuclear lamina proteins, including emerin, is found in many cancers and this expression is correlated with better clinical outcomes. A model is emerging whereby emerin, as well as other nuclear lamina proteins, binding to the nucleoskeleton regulates the nuclear structure to impact metastasis. In this model, emerin and lamins play a central role in metastatic transformation, since decreased emerin expression during transformation causes the nuclear structural defects required for increased cell migration, intravasation, and extravasation. Herein, we discuss the cellular functions of nuclear lamina proteins, with a particular focus on emerin, and how these functions impact cancer progression and metastasis.
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13
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Forlani G, Di Ventura B. A light way for nuclear cell biologists. J Biochem 2021; 169:273-286. [PMID: 33245128 PMCID: PMC8053400 DOI: 10.1093/jb/mvaa139] [Citation(s) in RCA: 7] [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: 10/30/2020] [Accepted: 11/12/2020] [Indexed: 12/11/2022] Open
Abstract
The nucleus is a very complex organelle present in eukaryotic cells. Having the crucial task to safeguard, organize and manage the genetic information, it must tightly control its molecular constituents, its shape and its internal architecture at any given time. Despite our vast knowledge of nuclear cell biology, much is yet to be unravelled. For instance, only recently we came to appreciate the existence of a dynamic nuclear cytoskeleton made of actin filaments that regulates processes such as gene expression, DNA repair and nuclear expansion. This suggests further exciting discoveries ahead of us. Modern cell biologists embrace a new methodology relying on precise perturbations of cellular processes that require a reversible, highly spatially confinable, rapid, inexpensive and tunEable external stimulus: light. In this review, we discuss how optogenetics, the state-of-the-art technology that uses genetically encoded light-sensitive proteins to steer biological processes, can be adopted to specifically investigate nuclear cell biology.
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Affiliation(s)
- Giada Forlani
- Spemann Graduate School of Biology and Medicine (SGBM)
- Centers for Biological Signalling Studies BIOSS and CIBSS
- Faculty of Biology, Institute of Biology II, Albert Ludwigs University of Freiburg, Freiburg, Germany
| | - Barbara Di Ventura
- Centers for Biological Signalling Studies BIOSS and CIBSS
- Faculty of Biology, Institute of Biology II, Albert Ludwigs University of Freiburg, Freiburg, Germany
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New Insights into Cellular Functions of Nuclear Actin. BIOLOGY 2021; 10:biology10040304. [PMID: 33916969 PMCID: PMC8067577 DOI: 10.3390/biology10040304] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/04/2021] [Revised: 03/30/2021] [Accepted: 04/01/2021] [Indexed: 12/12/2022]
Abstract
Simple Summary It is well known that actin forms a cytoplasmic network of microfilaments, the part of the cytoskeleton, in the cytoplasm of eukaryotic cells. The presence of nuclear actin was elusive for a very long time. Now, there is a very strong evidence that actin plays many important roles in the nucleus. Here, we discuss the recently discovered functions of the nuclear actin pool. Actin does not have nuclear localization signal (NLS), so its import to the nucleus is facilitated by the NLS-containing proteins. Nuclear actin plays a role in the maintenance of the nuclear structure and the nuclear envelope breakdown. It is also involved in chromatin remodeling, and chromatin and nucleosome movement necessary for DNA recombination, repair, and the initiation of transcription. It also binds RNA polymerases, promoting transcription. Because of the multifaceted role of nuclear actin, the future challenge will be to further define its functions in various cellular processes and diseases. Abstract Actin is one of the most abundant proteins in eukaryotic cells. There are different pools of nuclear actin often undetectable by conventional staining and commercial antibodies used to identify cytoplasmic actin. With the development of more sophisticated imaging and analytical techniques, it became clear that nuclear actin plays a crucial role in shaping the chromatin, genomic, and epigenetic landscape, transcriptional regulation, and DNA repair. This multifaceted role of nuclear actin is not only important for the function of the individual cell but also for the establishment of cell fate, and tissue and organ differentiation during development. Moreover, the changes in the nuclear, chromatin, and genomic architecture are preamble to various diseases. Here, we discuss some of the newly described functions of nuclear actin.
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15
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Franke K, Wang Z, Zuberbier T, Babina M. Cytokines Stimulated by IL-33 in Human Skin Mast Cells: Involvement of NF-κB and p38 at Distinct Levels and Potent Co-Operation with FcεRI and MRGPRX2. Int J Mol Sci 2021; 22:ijms22073580. [PMID: 33808264 PMCID: PMC8036466 DOI: 10.3390/ijms22073580] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 03/26/2021] [Accepted: 03/28/2021] [Indexed: 12/13/2022] Open
Abstract
The IL-1 family cytokine IL-33 activates and re-shapes mast cells (MCs), but whether and by what mechanisms it elicits cytokines in MCs from human skin remains poorly understood. The current study found that IL-33 activates CCL1, CCL2, IL-5, IL-8, IL-13, and TNF-α, while IL-1β, IL-6, IL-31, and VEGFA remain unaffected in cutaneous MCs, highlighting that each MC subset responds to IL-33 with a unique cytokine profile. Mechanistically, IL-33 induced the rapid (1–2 min) and durable (2 h) phosphorylation of p38, whereas the phosphorylation of JNK was weaker and more transient. Moreover, the NF-κB pathway was potently activated, as revealed by IκB degradation, increased nuclear abundance of p50/p65, and vigorous phosphorylation of p65. The activation of NF-κB occurred independently of p38 or JNK. The induced transcription of the cytokines selected for further study (CCL1, CCL2, IL-8, TNF-α) was abolished by interference with NF-κB, while p38/JNK had only some cytokine-selective effects. Surprisingly, at the level of the secreted protein products, p38 was nearly as effective as NF-κB for all entities, suggesting post-transcriptional involvement. IL-33 did not only instruct skin MCs to produce selected cytokines, but it also efficiently co-operated with the allergic and pseudo-allergic/neurogenic activation networks in the production of IL-8, TNF-α, CCL1, and CCL2. Synergism was more pronounced at the protein than at the mRNA level and appeared stronger for MRGPRX2 ligands than for FcεRI. Our results underscore the pro-inflammatory nature of an acute IL-33 stimulus and imply that especially in combination with allergens or MRGPRX2 agonists, IL-33 will efficiently amplify skin inflammation and thereby aggravate inflammatory dermatoses.
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Affiliation(s)
- Kristin Franke
- Department of Dermatology, Venerology and Allergology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, Germany; (K.F.); (Z.W.); (T.Z.)
| | - Zhao Wang
- Department of Dermatology, Venerology and Allergology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, Germany; (K.F.); (Z.W.); (T.Z.)
- Department of Dermatology, The Second Affiliated Hospital, Northwest Hospital, Xi’an Jiaotong University, Xi’an 710004, China
| | - Torsten Zuberbier
- Department of Dermatology, Venerology and Allergology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, Germany; (K.F.); (Z.W.); (T.Z.)
| | - Magda Babina
- Department of Dermatology, Venerology and Allergology, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, Germany; (K.F.); (Z.W.); (T.Z.)
- Correspondence: ; Tel.: +49-175-1649-539; Fax: +49-30-45051-8900
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16
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Xie X, Mahmood SR, Gjorgjieva T, Percipalle P. Emerging roles of cytoskeletal proteins in regulating gene expression and genome organization during differentiation. Nucleus 2020; 11:53-65. [PMID: 32212905 PMCID: PMC7289583 DOI: 10.1080/19491034.2020.1742066] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
In the eukaryotic cell nucleus, cytoskeletal proteins are emerging as essential players in nuclear function. In particular, actin regulates chromatin as part of ATP-dependent chromatin remodeling complexes, it modulates transcription and it is incorporated into nascent ribonucleoprotein complexes, accompanying them from the site of transcription to polyribosomes. The nuclear actin pool is undistinguishable from the cytoplasmic one in terms of its ability to undergo polymerization and it has also been implicated in the dynamics of chromatin, regulating heterochromatin segregation at the nuclear lamina and maintaining heterochromatin levels in the nuclear interiors. One of the next frontiers is, therefore, to determine a possible involvement of nuclear actin in the functional architecture of the cell nucleus by regulating the hierarchical organization of chromatin and, thus, genome organization. Here, we discuss the repertoire of these potential actin functions and how they are likely to play a role in the context of cellular differentiation.
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Affiliation(s)
- Xin Xie
- Science Division, Biology Program, New York University Abu Dhabi (NYUAD), Abu Dhabi, United Arab Emirates
| | - S Raza Mahmood
- Science Division, Biology Program, New York University Abu Dhabi (NYUAD), Abu Dhabi, United Arab Emirates.,Department of Biology, New York University, New York, NY, USA
| | - Tamara Gjorgjieva
- Science Division, Biology Program, New York University Abu Dhabi (NYUAD), Abu Dhabi, United Arab Emirates
| | - Piergiorgio Percipalle
- Science Division, Biology Program, New York University Abu Dhabi (NYUAD), Abu Dhabi, United Arab Emirates.,Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden
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17
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Kopfer KH, Jäger W, Matthäus F. A mechanochemical model for rho GTPase mediated cell polarization. J Theor Biol 2020; 504:110386. [DOI: 10.1016/j.jtbi.2020.110386] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2020] [Revised: 06/15/2020] [Accepted: 06/17/2020] [Indexed: 01/13/2023]
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18
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Hao T, Gan YH. ΔNp63α promotes the expression and nuclear translocation of PTEN, leading to cisplatin resistance in oral cancer cells. Am J Transl Res 2020; 12:6187-6203. [PMID: 33194023 PMCID: PMC7653557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Accepted: 09/03/2020] [Indexed: 06/11/2023]
Abstract
Pan-histone deacetylase (HDAC) inhibitors can induce the expression of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) protein. However, the underlying mechanism by which this occurs remains unclear. In this study, we show that pan-HDAC inhibitors, including trichostatin A, suberoylanilide hydroxamic acid, and sodium butyrate, were able to induce PTEN mRNA and protein expression via the acetylation of the transcription factor ΔNp63α by inhibiting HDAC1 and HDAC3. ΔNp63α enhanced PTEN promoter activity by binding two newly identified recognition sites on it. Unfortunately, the inhibition of HDAC1 or HDAC3 failed to activate PTEN, as knockdown of HDAC1 inhibited both membrane-bound and nuclear PTEN, and knockdown of HDAC3 only induced cytoplasmic PTEN. Furthermore, the overexpression of ΔNp63α downregulated membrane-bound PTEN but enhanced the nuclear translocation of PTEN, leading to the cisplatin resistance of oral cancer cells. PTEN accumulated in the nuclei of cancerous cells and normal cells when ΔNp63α was highly expressed in specimens from patients with squamous cell carcinoma of the tongue. However, inhibiting either HDAC1 or HDAC6 prevented the nuclear translocation of PTEN and attenuated cisplatin resistance. These results suggest that chemotherapeutic inhibitors of HDAC1 or HDAC6, together with cisplatin, might improve outcomes for patients with squamous cell carcinoma of the tongue.
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Affiliation(s)
- Ting Hao
- Central Laboratory, Peking University School and Hospital of Stomatology22 Zhongguancun Avenue South, Haidian District, Beijing 100081, China
- Department of Oral & Maxillofacial, Peking University School and Hospital of Stomatology22 Zhongguancun Avenue South, Haidian District, Beijing 100081, China
| | - Ye-Hua Gan
- Central Laboratory, Peking University School and Hospital of Stomatology22 Zhongguancun Avenue South, Haidian District, Beijing 100081, China
- Department of Oral & Maxillofacial, Peking University School and Hospital of Stomatology22 Zhongguancun Avenue South, Haidian District, Beijing 100081, China
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19
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Krippner S, Winkelmeier J, Knerr J, Brandt DT, Virant D, Schwan C, Endesfelder U, Grosse R. Postmitotic expansion of cell nuclei requires nuclear actin filament bundling by α-actinin 4. EMBO Rep 2020; 21:e50758. [PMID: 32959960 PMCID: PMC7645226 DOI: 10.15252/embr.202050758] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 08/18/2020] [Accepted: 08/20/2020] [Indexed: 12/13/2022] Open
Abstract
The actin cytoskeleton operates in a multitude of cellular processes including cell shape and migration, mechanoregulation, and membrane or organelle dynamics. However, its filamentous properties and functions inside the mammalian cell nucleus are less well explored. We previously described transient actin assembly at mitotic exit that promotes nuclear expansion during chromatin decondensation. Here, we identify non‐muscle α‐actinin 4 (ACTN4) as a critical regulator to facilitate F‐actin reorganization and bundling during postmitotic nuclear expansion. ACTN4 binds to nuclear actin filament structures, and ACTN4 clusters associate with nuclear F‐actin in a highly dynamic fashion. ACTN4 but not ACTN1 is required for proper postmitotic nuclear volume expansion, mediated by its actin‐binding domain. Using super‐resolution imaging to quantify actin filament numbers and widths in individual nuclei, we find that ACTN4 is necessary for postmitotic nuclear actin reorganization and actin filament bundling. Our findings uncover a nuclear cytoskeletal function for ACTN4 to control nuclear size and chromatin organization during mitotic cell division.
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Affiliation(s)
- Sylvia Krippner
- Institute of Pharmacology, University of Freiburg, Freiburg, Germany
| | - Jannik Winkelmeier
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Julian Knerr
- Institute of Pharmacology, University of Freiburg, Freiburg, Germany
| | | | - David Virant
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Carsten Schwan
- Institute of Pharmacology, University of Freiburg, Freiburg, Germany
| | - Ulrike Endesfelder
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg, Germany
| | - Robert Grosse
- Institute of Pharmacology, University of Freiburg, Freiburg, Germany.,Centre for Integrative Biological Signalling Studies, Freiburg, Germany
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20
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Abstract
The presence of actin in the nucleus has been a matter of debate for many years. In recent years many important roles of actin in the nucleus (transcriptional regulation, chromatin remodeling, DNA repair, cell division, maintenance of nuclear architecture) have been identified, and the precise control of nuclear actin levels has been demonstrated. The vital importance of the actin driven processes in the cell make it highly likely that dysregulation of nuclear actin dynamics and structure can be linked to tumor induction and -progression. In this chapter I summarize our current knowledge about nuclear actin in the cancer context.
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21
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Abstract
The presence of actin in the nucleus has historically been a highly contentious issue. It is now, however, well accepted that actin has physiologically important roles in the nucleus. In this Review, we describe the evolution of our thinking about actin in the nucleus starting with evidence supporting its involvement in transcription, chromatin remodeling and intranuclear movements. We also review the growing literature on the mechanisms that regulate the import and export of actin and how post-translational modifications of actin could regulate nuclear actin. We end with an extended discussion of the role of nuclear actin in the repair of DNA double stranded breaks.
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Affiliation(s)
- Leonid Serebryannyy
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, United States
| | - Primal de Lanerolle
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, United States.
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22
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Nuclear actin dynamics in gene expression and genome organization. Semin Cell Dev Biol 2020; 102:105-112. [DOI: 10.1016/j.semcdb.2019.10.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 08/28/2019] [Accepted: 10/24/2019] [Indexed: 11/19/2022]
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23
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Lawrimore CJ, Lawrimore J, He Y, Chavez S, Bloom K. Polymer perspective of genome mobilization. Mutat Res 2020; 821:111706. [PMID: 32516654 DOI: 10.1016/j.mrfmmm.2020.111706] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 04/30/2020] [Accepted: 05/06/2020] [Indexed: 02/07/2023]
Abstract
Chromosome motion is an intrinsic feature of all DNA-based metabolic processes and is a particularly well-documented response to both DNA damage and repair. By using both biological and polymer physics approaches, many of the contributing factors of chromatin motility have been elucidated. These include the intrinsic properties of chromatin, such as stiffness, as well as the loop modulators condensin and cohesin. Various biological factors such as external tethering to nuclear domains, ATP-dependent processes, and nucleofilaments further impact chromatin motion. DNA damaging agents that induce double-stranded breaks also cause increased chromatin motion that is modulated by recruitment of repair and checkpoint proteins. Approaches that integrate biological experimentation in conjunction with models from polymer physics provide mechanistic insights into the role of chromatin dynamics in biological function. In this review we discuss the polymer models and the effects of both DNA damage and repair on chromatin motion as well as mechanisms that may underlie these effects.
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Affiliation(s)
- Colleen J Lawrimore
- Department of Biology, 623 Fordham Hall CB#3280, University of North Carolina, Chapel Hill, NC 27599-3280, United States
| | - Josh Lawrimore
- Department of Biology, 623 Fordham Hall CB#3280, University of North Carolina, Chapel Hill, NC 27599-3280, United States
| | - Yunyan He
- Department of Biology, 623 Fordham Hall CB#3280, University of North Carolina, Chapel Hill, NC 27599-3280, United States
| | - Sergio Chavez
- Department of Biology, 623 Fordham Hall CB#3280, University of North Carolina, Chapel Hill, NC 27599-3280, United States
| | - Kerry Bloom
- Department of Biology, 623 Fordham Hall CB#3280, University of North Carolina, Chapel Hill, NC 27599-3280, United States.
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The Actin-Family Protein Arp4 Is a Novel Suppressor for the Formation and Functions of Nuclear F-Actin. Cells 2020; 9:cells9030758. [PMID: 32204557 PMCID: PMC7140684 DOI: 10.3390/cells9030758] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/06/2020] [Accepted: 03/17/2020] [Indexed: 12/20/2022] Open
Abstract
The crosstalk between actin and actin-related proteins (Arps), namely Arp2 and Arp3, plays a central role in facilitating actin polymerization in the cytoplasm and also in the nucleus. Nuclear F-actin is required for transcriptional regulation, double-strand break repair, and nuclear organization. The formation of nuclear F-actin is highly dynamic, suggesting the involvement of positive and negative regulators for nuclear actin polymerization. While actin assembly factors for nuclear F-actin have been recently described, information about inhibitory factors is still limited. The actin-related protein Arp4 which is predominantly localized in the nucleus, has been previously identified as an integral subunit of multiple chromatin modulation complexes, where it forms a heterodimer with monomeric actin. Therefore, we tested whether Arp4 functions as a suppressor of nuclear F-actin formation. The knockdown of Arp4 (Arp4 KD) led to an increase in nuclear F-actin formation in NIH3T3 cells, and purified Arp4 potently inhibited F-actin formation in mouse nuclei transplanted into Xenopus laevis oocytes. Consistently, Arp4 KD facilitated F-actin-inducible gene expression (e.g., OCT4) and DNA damage repair. Our results suggest that Arp4 has a critical role in the formation and functions of nuclear F-actin.
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25
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Percipalle P, Vartiainen M. Cytoskeletal proteins in the cell nucleus: a special nuclear actin perspective. Mol Biol Cell 2020; 30:1781-1785. [PMID: 31306096 PMCID: PMC6727747 DOI: 10.1091/mbc.e18-10-0645] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The emerging role of cytoskeletal proteins in the cell nucleus has become a new frontier in cell biology. Actin and actin-binding proteins regulate chromatin and gene expression, but importantly they are beginning to be essential players in genome organization. These actin-based functions contribute to genome stability and integrity while affecting DNA replication and global transcription patterns. This is likely to occur through interactions of actin with nuclear components including nuclear lamina and subnuclear organelles. An exciting future challenge is to understand how these actin-based genome-wide mechanisms may regulate development and differentiation by interfering with the mechanical properties of the cell nucleus and how regulated actin polymerization plays a role in maintaining nuclear architecture. With a special focus on actin, here we summarize how cytoskeletal proteins operate in the nucleus and how they may be important to consolidate nuclear architecture for sustained gene expression or silencing.
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Affiliation(s)
- Piergiorgio Percipalle
- Biology Program, Science Division, New York University Abu Dhabi, 12988 Abu Dhabi, United Arab Emirates.,Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, SE-106 91 Stockholm, Sweden
| | - Maria Vartiainen
- Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, 00014 Helsinki, Finland
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27
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Venit T, Mahmood SR, Endara-Coll M, Percipalle P. Nuclear actin and myosin in chromatin regulation and maintenance of genome integrity. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2020; 355:67-108. [DOI: 10.1016/bs.ircmb.2020.05.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/06/2022]
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28
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Lambert MW. The functional importance of lamins, actin, myosin, spectrin and the LINC complex in DNA repair. Exp Biol Med (Maywood) 2019; 244:1382-1406. [PMID: 31581813 PMCID: PMC6880146 DOI: 10.1177/1535370219876651] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Three major proteins in the nucleoskeleton, lamins, actin, and spectrin, play essential roles in maintenance of nuclear architecture and the integrity of the nuclear envelope, in mechanotransduction and mechanical coupling between the nucleoskeleton and cytoskeleton, and in nuclear functions such as regulation of gene expression, transcription and DNA replication. Less well known, but critically important, are the role these proteins play in DNA repair. The A-type and B-type lamins, nuclear actin and myosin, spectrin and the LINC (linker of nucleoskeleton and cytoskeleton) complex each function in repair of DNA damage utilizing various repair pathways. The lamins play a role in repair of DNA double-strand breaks (DSBs) by nonhomologous end joining (NHEJ) or homologous recombination (HR). Actin is involved in repair of DNA DSBs and interacts with myosin in facilitating relocalization of these DSBs in heterochromatin for HR repair. Nonerythroid alpha spectrin (αSpII) plays a critical role in repair of DNA interstrand cross-links (ICLs) where it acts as a scaffold in recruitment of repair proteins to sites of damage and is important in the initial damage recognition and incision steps of the repair process. The LINC complex contributes to the repair of DNA DSBs and ICLs. This review will address the important functions of these proteins in the DNA repair process, their mechanism of action, and the profound impact a defect or deficiency in these proteins has on cellular function. The critical roles of these proteins in DNA repair will be further emphasized by discussing the human disorders and the pathophysiological changes that result from or are related to deficiencies in these proteins. The demonstrated function for each of these proteins in the DNA repair process clearly indicates that there is another level of complexity that must be considered when mechanistically examining factors crucial for DNA repair.
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Affiliation(s)
- Muriel W Lambert
- Department of Pathology, Immunology and Laboratory
Medicine, Rutgers New Jersey Medical School, Newark, NJ 07103, USA
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29
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HIV-1 Vpr mediates the depletion of the cellular repressor CTIP2 to counteract viral gene silencing. Sci Rep 2019; 9:13154. [PMID: 31511615 PMCID: PMC6739472 DOI: 10.1038/s41598-019-48689-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 08/07/2019] [Indexed: 12/15/2022] Open
Abstract
Mammals have evolved many antiviral factors impacting different steps of the viral life cycle. Associated with chromatin-modifying enzymes, the cellular cofactor CTIP2 contributes to HIV-1 gene silencing in latently infected reservoirs that constitute the major block toward an HIV cure. We report, for the first time, that the virus has developed a strategy to overcome this major transcriptional block. Productive HIV-1 infection results in a Vpr-mediated depletion of CTIP2 in microglial cells and CD4+ T cells, two of the major viral reservoirs. Associated to the Cul4A-DDB1-DCAF1 ubiquitin ligase complex, Vpr promotes CTIP2 degradation via the proteasome pathway in the nuclei of target cells and notably at the latent HIV-1 promoter. Importantly, Vpr targets CTIP2 associated with heterochromatin-promoting enzymes dedicated to HIV-1 gene silencing. Thereby, Vpr reactivates HIV-1 expression in a microglial model of HIV-1 latency. Altogether our results suggest that HIV-1 Vpr mediates the depletion of the cellular repressor CTIP2 to counteract viral gene silencing.
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30
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Sankaran J, Uzer G, van Wijnen AJ, Rubin J. Gene regulation through dynamic actin control of nuclear structure. Exp Biol Med (Maywood) 2019; 244:1345-1353. [PMID: 31084213 DOI: 10.1177/1535370219850079] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Bone marrow mesenchymal stem cells exist in a multipotential state, where osteogenic and adipogenic genomes are silenced in heterochromatin at the inner nuclear leaflet. Physical force, generated in the marrow space during dynamic exercise exerts control overexpression of differentiation. Mesenchymal stem cells experience mechanical force through their cytoskeletal attachments to substrate, inducing signaling that alters gene expression. The generated force is further transferred from the cytoskeleton to the nucleoskeleton through tethering of actin to Linker of Nucleus and Cytoskeleton (LINC) complexes. Forces exerted on LINC alter the shape and placement of the nucleus within the cell, and are ultimately transferred into the nucleus. LINC complexes transverse the nuclear membrane and connect to the internal nucleoskeleton that is made up of lamin filaments and actin. Force transfer through LINC thus causes structural rearrangements of the nuclear scaffolding upon which chromosomes are arranged. Gene availability is not only modulated through heterochromatin remodeling enzymes and active transcription factors but also by control of nucleoskeletal structure and nuclear enzymes that mediate actin polymerization in the nucleus. Nuclear actin structure may be affected by similar force-activated pathways as those controlling the cytoplasmic actin cytoskeleton and represent a critical determinant of mesenchymal stem cell lineage commitment. Impact statement Gene expression is controlled by nuclear structure which is modulated by both internal and external forces exerted on the nucleoskeleton. Extracellular forces experienced through the actin cytoskeleton are transmitted to the internal nucleoskeleton via Linker of Nucleus and Cytoskeleton (LINC) protein connections. LINC complexes directly alter nuclear shape and entry of molecules that regulate transcription. New mechanistic models indicate that nuclear actin is a dynamic component of the filamentous nucleoskeleton and modified by an intranuclear “actin toolbox”, a set of enzymes that regulate linear and branched polymerization of nuclear actin. External stimulation of both biomechanical and biochemical pathways alters nuclear actin structure and has profound effects on gene expression by controlling chromatin architecture and transcription factor access to gene targets. The available data indicate that nucleoskeletal control of gene expression is critical for self-renewal and mesenchymal lineage-allocation in stem cells.
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Affiliation(s)
- Jeyantt Sankaran
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Gunes Uzer
- College of Mechanical and Biomedical Engineering, Boise State University, Boise, ID 83725, USA
| | - Andre J van Wijnen
- Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN 55905, USA.,Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, MN 55905, USA
| | - Janet Rubin
- Department of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
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Ilicheva NV, Pochukalina GN, Podgornaya OI. Actin depolymerization disrupts karyosphere capsule integrity but not residual transcription in late oocytes of the grass frog Rana temporaria. J Cell Biochem 2019; 120:15057-15068. [PMID: 31081178 DOI: 10.1002/jcb.28767] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 01/18/2019] [Accepted: 01/24/2019] [Indexed: 12/30/2022]
Abstract
Late diplotene oocytes are characterized by an essential decrease in transcriptional activity. At this time, chromosomes condense and form a compact structure named a karyosphere. The karyosphere of grass frogs Rana temporaria is surrounded by a fibrillar karyosphere capsule (KC). One of the main protein constituents of R. temporaria KC is actin. In this study, we used antibodies against different actin epitopes to trace different forms of actin in the KC. We also investigated the effect of F-actin depolymerization on the oocyte nuclear structures and transcription of chromatin DNA and rDNA in the amplified nucleoli. It was determined that disruption of actin filaments leads to chromosome shrinkage, nucleoli fusion, and distortion of the KC structure, but does not inhibit residual transcription in both the karyosphere and the nucleoli.
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Affiliation(s)
- Nadya V Ilicheva
- Institute of Cytology of Russian Academy of Sciences, Saint Petersburg, Russia
| | | | - Olga I Podgornaya
- Institute of Cytology of Russian Academy of Sciences, Saint Petersburg, Russia.,Saint Petersburg University, Saint Petersburg, Russia.,Far Eastern Federal University, Vladivostok, Russia
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32
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Hurst V, Shimada K, Gasser SM. Nuclear Actin and Actin-Binding Proteins in DNA Repair. Trends Cell Biol 2019; 29:462-476. [PMID: 30954333 DOI: 10.1016/j.tcb.2019.02.010] [Citation(s) in RCA: 81] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/25/2019] [Accepted: 02/26/2019] [Indexed: 12/27/2022]
Abstract
Nuclear actin has been implicated in a variety of DNA-related processes including chromatin remodeling, transcription, replication, and DNA repair. However, the mechanistic understanding of actin in these processes has been limited, largely due to a lack of research tools that address the roles of nuclear actin specifically, that is, distinct from its cytoplasmic functions. Recent findings support a model for homology-directed DNA double-strand break (DSB) repair in which a complex of ARP2 and ARP3 (actin-binding proteins 2 and 3) binds at the break and works with actin to promote DSB clustering and homology-directed repair. Further, it has been reported that relocalization of heterochromatic DSBs to the nuclear periphery in Drosophila is ARP2/3 dependent and actin-myosin driven. Here we provide an overview of the role of nuclear actin and actin-binding proteins in DNA repair, critically evaluating the experimental tools used and potential indirect effects.
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Affiliation(s)
- Verena Hurst
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland; University of Basel, Faculty of Natural Sciences, CH-4056 Basel, Switzerland
| | - Kenji Shimada
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland
| | - Susan M Gasser
- Friedrich Miescher Institute for Biomedical Research, CH-4058 Basel, Switzerland; University of Basel, Faculty of Natural Sciences, CH-4056 Basel, Switzerland.
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33
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Gegenfurtner FA, Zisis T, Al Danaf N, Schrimpf W, Kliesmete Z, Ziegenhain C, Enard W, Kazmaier U, Lamb DC, Vollmar AM, Zahler S. Transcriptional effects of actin-binding compounds: the cytoplasm sets the tone. Cell Mol Life Sci 2018; 75:4539-4555. [PMID: 30206640 PMCID: PMC11105542 DOI: 10.1007/s00018-018-2919-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/19/2018] [Accepted: 08/14/2018] [Indexed: 12/23/2022]
Abstract
Actin has emerged as a versatile regulator of gene transcription. Cytoplasmatic actin regulates mechanosensitive-signaling pathways such as MRTF-SRF and Hippo-YAP/TAZ. In the nucleus, both polymerized and monomeric actin directly interfere with transcription-associated molecular machineries. Natural actin-binding compounds are frequently used tools to study actin-related processes in cell biology. However, their influence on transcriptional regulation and intranuclear actin polymerization is poorly understood to date. Here, we analyze the effects of two representative actin-binding compounds, Miuraenamide A (polymerizing properties) and Latrunculin B (depolymerizing properties), on transcriptional regulation in primary cells. We find that actin stabilizing and destabilizing compounds inversely shift nuclear actin levels without a direct influence on polymerization state and intranuclear aspects of transcriptional regulation. Furthermore, we identify Miuraenamide A as a potent inducer of G-actin-dependent SRF target gene expression. In contrast, the F-actin-regulated Hippo-YAP/TAZ axis remains largely unaffected by compound-induced actin aggregation. This is due to the inability of AMOTp130 to bind to the amorphous actin aggregates resulting from treatment with miuraenamide. We conclude that actin-binding compounds predominantly regulate transcription via their influence on cytoplasmatic G-actin levels, while transcriptional processes relying on intranuclear actin polymerization or functional F-actin networks are not targeted by these compounds at tolerable doses.
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Affiliation(s)
- Florian A Gegenfurtner
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-University Munich, 81377, Munich, Germany
| | - Themistoklis Zisis
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-University Munich, 81377, Munich, Germany
| | - Nader Al Danaf
- Department of Chemistry, Munich Center for Integrated Protein Science, Nanosystems Initiative Munich and Centre for Nanoscience, Ludwig-Maximilians-University Munich, 81377, Munich, Germany
| | - Waldemar Schrimpf
- Department of Chemistry, Munich Center for Integrated Protein Science, Nanosystems Initiative Munich and Centre for Nanoscience, Ludwig-Maximilians-University Munich, 81377, Munich, Germany
| | - Zane Kliesmete
- Department Biology II, Anthropology and Human Genomics, Ludwig-Maximilians-University Munich, 82152, Martinsried, Germany
| | - Christoph Ziegenhain
- Department Biology II, Anthropology and Human Genomics, Ludwig-Maximilians-University Munich, 82152, Martinsried, Germany
| | - Wolfgang Enard
- Department Biology II, Anthropology and Human Genomics, Ludwig-Maximilians-University Munich, 82152, Martinsried, Germany
| | - Uli Kazmaier
- Institute of Organic Chemistry, Saarland University, 66041, Saarbrücken, Germany
| | - Don C Lamb
- Department of Chemistry, Munich Center for Integrated Protein Science, Nanosystems Initiative Munich and Centre for Nanoscience, Ludwig-Maximilians-University Munich, 81377, Munich, Germany
| | - Angelika M Vollmar
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-University Munich, 81377, Munich, Germany
| | - Stefan Zahler
- Department of Pharmacy, Center for Drug Research, Ludwig-Maximilians-University Munich, 81377, Munich, Germany.
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Wineland DM, Kelpsch DJ, Tootle TL. Multiple Pools of Nuclear Actin. Anat Rec (Hoboken) 2018; 301:2014-2036. [PMID: 30312534 PMCID: PMC6293971 DOI: 10.1002/ar.23964] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 04/14/2018] [Accepted: 04/17/2018] [Indexed: 02/06/2023]
Abstract
While nuclear actin was reported ~50 years ago, it's in vivo prevalence and structure remain largely unknown. Here, we use Drosophila oogenesis, that is, follicle development, to characterize nuclear actin. We find that three different reagents-DNase I, anti-actin C4, and anti-actin AC15-recognize distinct pools of nuclear actin. DNase I labels monomeric or G-actin, and, during follicle development, G-actin is present in the nucleus of every cell. Some G-actin is recognized by the C4 antibody. In particular, C4 nuclear actin colocalizes with DNase I to the nucleolus in anterior escort cells, follicle stem cells, some mitotic follicle cells, and a subset of nurse cells during early oogenesis. C4 also labels polymeric nuclear actin in the nucleoplasm of the germline stem cells, early cystoblasts, and oocytes. The AC15 antibody labels a completely distinct pool of nuclear actin from that of DNase I and C4. Specifically, AC15 nuclear actin localizes to the chromatin in the nurse and follicle cells during mid-to-late oogenesis. Within the oocyte, AC15 nuclear actin progresses from localizing to puncta surrounding the DNA, to forming a filamentous cage around the chromosomes. Together these findings reveal that nuclear actin is highly prevalent in vivo, and multiple pools of nuclear actin exist and can be recognized using different reagents. Additionally, our localization studies suggest that nuclear actin may regulate stemness, nucleolar structure and function, transcription, and nuclear structure. Such findings call for further studies to explore the prevalence, diversity, and functions of nuclear actin across tissues and organisms. Anat Rec, 301:2014-2036, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Dylane M. Wineland
- Anatomy and Cell Biology, University of Iowa Carver College of
Medicine, 51 Newton Rd, 1-500 BSB, Iowa City, IA 52242
| | - Daniel J. Kelpsch
- Anatomy and Cell Biology, University of Iowa Carver College of
Medicine, 51 Newton Rd, 1-500 BSB, Iowa City, IA 52242
| | - Tina L. Tootle
- Anatomy and Cell Biology, University of Iowa Carver College of
Medicine, 51 Newton Rd, 1-500 BSB, Iowa City, IA 52242
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35
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Kelpsch DJ, Tootle TL. Nuclear Actin: From Discovery to Function. Anat Rec (Hoboken) 2018; 301:1999-2013. [PMID: 30312531 PMCID: PMC6289869 DOI: 10.1002/ar.23959] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 04/20/2018] [Accepted: 05/14/2018] [Indexed: 01/02/2023]
Abstract
While actin was discovered in the nucleus over 50 years ago, research lagged for decades due to strong skepticism. The revitalization of research into nuclear actin occurred after it was found that cellular stresses induce the nuclear localization and alter the structure of actin. These studies provided the first hints that actin has a nuclear function. Subsequently, it was established that the nuclear import and export of actin is highly regulated. While the structures of nuclear actin remain unclear, it can function as monomers, polymers, and even rods. Furthermore, even within a given structure, distinct pools of nuclear actin that can be differentially labeled have been identified. Numerous mechanistic studies have uncovered an array of functions for nuclear actin. It regulates the activity of RNA polymerases, as well as specific transcription factors. Actin also modulates the activity of several chromatin remodeling complexes and histone deacetylases, to ultimately impinge on transcriptional programing and DNA damage repair. Further, nuclear actin mediates chromatin movement and organization. It has roles in meiosis and mitosis, and these functions may be functionally conserved from ancient bacterial actin homologs. The structure and integrity of the nuclear envelope and sub-nuclear compartments are also regulated by nuclear actin. Furthermore, nuclear actin contributes to human diseases like cancer, neurodegeneration, and myopathies. Here, we explore the early discovery of actin in the nucleus and discuss the forms and functions of nuclear actin in both normal and disease contexts. Anat Rec, 301:1999-2013, 2018. © 2018 Wiley Periodicals, Inc.
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Affiliation(s)
- Daniel J. Kelpsch
- Anatomy and Cell Biology, University of Iowa Carver College of Medicine, 51 Newton Rd, 1-500 BSB, Iowa City, IA 52242
| | - Tina L. Tootle
- Anatomy and Cell Biology, University of Iowa Carver College of Medicine, 51 Newton Rd, 1-500 BSB, Iowa City, IA 52242
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36
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Nuclear Actin Polymerized by mDia2 Confines Centromere Movement during CENP-A Loading. iScience 2018; 9:314-327. [PMID: 30448731 PMCID: PMC6240728 DOI: 10.1016/j.isci.2018.10.031] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 10/04/2018] [Accepted: 10/29/2018] [Indexed: 12/31/2022] Open
Abstract
Centromeres are specialized chromosomal regions epigenetically defined by the histone H3 variant centromere protein A (CENP-A). CENP-A needs to be replenished in every cell cycle, but how new CENP-A is stably incorporated into centromeric chromatin remains unclear. We have discovered that a cytoskeletal protein, diaphanous formin mDia2, is essential for the stable incorporation of new CENP-A proteins into centromeric nucleosomes. Here we report that mDia2-mediated formation of dynamic and short nuclear actin filaments in G1 nucleus is required to maintain CENP-A levels at the centromere. Importantly, mDia2 and nuclear actin are required for constrained centromere movement during CENP-A loading, and depleting nuclear actin or MgcRacGAP, which lies upstream of mDia2, extends centromeric association of the CENP-A loading chaperone Holliday junction recognition protein (HJURP). Our findings thus suggest that nuclear actin polymerized by mDia2 contributes to the physical confinement of G1 centromeres so that HJURP-mediated CENP-A loading reactions can be productive, and centromere's epigenetic identity can be stably maintained. Formin mDia2 is required for nuclear actin polymerization at G1 centromeres Nuclear actin polymerization is required to maintain centromeric CENP-A levels mDia2 and nuclear actin restrict centromere movement during CENP-A loading Nuclear actin and MgcRacGAP are required for timely turnover of centromeric HJURP
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37
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Klages-Mundt NL, Kumar A, Zhang Y, Kapoor P, Shen X. The Nature of Actin-Family Proteins in Chromatin-Modifying Complexes. Front Genet 2018; 9:398. [PMID: 30319687 PMCID: PMC6167448 DOI: 10.3389/fgene.2018.00398] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 08/31/2018] [Indexed: 01/25/2023] Open
Abstract
Actin is not only one of the most abundant proteins in eukaryotic cells, but also one of the most versatile. In addition to its familiar involvement in enabling contraction and establishing cellular motility and scaffolding in the cytosol, actin has well-documented roles in a variety of processes within the confines of the nucleus, such as transcriptional regulation and DNA repair. Interestingly, monomeric actin as well as actin-related proteins (Arps) are found as stoichiometric subunits of a variety of chromatin remodeling complexes and histone acetyltransferases, raising the question of precisely what roles they serve in these contexts. Actin and Arps are present in unique combinations in chromatin modifiers, helping to establish structural integrity of the complex and enabling a wide range of functions, such as recruiting the complex to nucleosomes to facilitate chromatin remodeling and promoting ATPase activity of the catalytic subunit. Actin and Arps are also thought to help modulate chromatin dynamics and maintain higher-order chromatin structure. Moreover, the presence of actin and Arps in several chromatin modifiers is necessary for promoting genomic integrity and an effective DNA damage response. In this review, we discuss the involvement of actin and Arps in these nuclear complexes that control chromatin remodeling and histone modifications, while also considering avenues for future study to further shed light on their functional importance.
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Affiliation(s)
- Naeh L Klages-Mundt
- Science Park Research Division, Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX, United States.,Program in Genetics & Epigenetics, The University of Texas MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States
| | - Ashok Kumar
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, TX, United States
| | - Yuexuan Zhang
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, China
| | - Prabodh Kapoor
- Department of Cellular and Molecular Biology, The University of Texas Health Science Center at Tyler, Tyler, TX, United States
| | - Xuetong Shen
- Science Park Research Division, Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX, United States.,Program in Genetics & Epigenetics, The University of Texas MD Anderson Cancer Center, UTHealth Graduate School of Biomedical Sciences, Houston, TX, United States
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38
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Fiore APZP, Spencer VA, Mori H, Carvalho HF, Bissell MJ, Bruni-Cardoso A. Laminin-111 and the Level of Nuclear Actin Regulate Epithelial Quiescence via Exportin-6. Cell Rep 2018; 19:2102-2115. [PMID: 28591581 DOI: 10.1016/j.celrep.2017.05.050] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Revised: 03/19/2017] [Accepted: 05/12/2017] [Indexed: 02/08/2023] Open
Abstract
Nuclear actin (N-actin) is known to participate in the regulation of gene expression. We showed previously that N-actin levels mediate the growth and quiescence of mouse epithelial cells in response to laminin-111 (LN1), a component of the mammary basement membrane (BM). We know that BM is defective in malignant cells, and we show here that it is the LN1/N-actin pathway that is aberrant in human breast cancer cells, leading to continuous growth. Photobleaching assays revealed that N-actin exit in nonmalignant cells begins as early as 30 min after LN1 treatment. LN1 attenuates the PI3K pathway leading to upregulation of exportin-6 (XPO6) activity and shuttles actin out of the nucleus. Silencing XPO6 prevents quiescence. Malignant cells are impervious to LN1 signaling. These results shed light on the crucial role of LN1 in quiescence and differentiation and how defects in the LN1/PI3K/XPO6/N-actin axis explain the loss of tissue homeostasis and growth control that contributes to malignant progression.
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Affiliation(s)
- Ana Paula Zen Petisco Fiore
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP 05508-000, Brazil
| | | | - Hidetoshi Mori
- Life Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Center for Comparative Medicine, University of California, Davis, Davis, CA 95616, USA
| | - Hernandes F Carvalho
- INFABiC - National Institute of Science and Technology on Photonics Applied to Cell Biology, Campinas, SP 13083-862, Brazil; Structural and Functional Biology Department, Institute of Biology, State University of Campinas, Campinas, SP 13083-865, Brazil
| | - Mina J Bissell
- Life Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
| | - Alexandre Bruni-Cardoso
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, SP 05508-000, Brazil; Life Science Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; INFABiC - National Institute of Science and Technology on Photonics Applied to Cell Biology, Campinas, SP 13083-862, Brazil.
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39
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The Role of Actin Dynamics and Actin-Binding Proteins Expression in Epithelial-to-Mesenchymal Transition and Its Association with Cancer Progression and Evaluation of Possible Therapeutic Targets. BIOMED RESEARCH INTERNATIONAL 2018; 2018:4578373. [PMID: 29581975 PMCID: PMC5822767 DOI: 10.1155/2018/4578373] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 12/19/2017] [Indexed: 12/21/2022]
Abstract
Metastasis causes death of 90% of cancer patients, so it is the most significant issue associated with cancer disease. Thus, it is no surprise that many researchers are trying to develop drugs targeting or preventing them. The secondary tumour site formation is closely related to phenomena like epithelial-to-mesenchymal and its reverse, mesenchymal-to-epithelial transition. The change of the cells' phenotype to mesenchymal involves the acquisition of migratory potential. Cancer cells movement is possible due to the development of invasive structures like invadopodia, lamellipodia, and filopodia. These changes are dependent on the reorganization of the actin cytoskeleton. In turn, the polymerization and depolymerization of actin are controlled by actin-binding proteins. In many tumour cells, the actin and actin-associated proteins are accumulated in the cell nucleus, suggesting that it may also affect the progression of cancer by regulating gene expression. Once the cancer cell reaches a new habitat it again acquires epithelial features and thus proliferative activity. Targeting of epithelial-to-mesenchymal or/and mesenchymal-to-epithelial transitions through regulation of their main components expression may be a potential solution to the problem of metastasis. This work focuses on the role of these processes in tumour progression and the assessment of therapeutic potential of agents targeting them.
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40
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Fili N, Hari-Gupta Y, Dos Santos Á, Cook A, Poland S, Ameer-Beg SM, Parsons M, Toseland CP. NDP52 activates nuclear myosin VI to enhance RNA polymerase II transcription. Nat Commun 2017; 8:1871. [PMID: 29187741 PMCID: PMC5707354 DOI: 10.1038/s41467-017-02050-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2017] [Accepted: 10/30/2017] [Indexed: 11/09/2022] Open
Abstract
Myosin VI (MVI) has been found to be overexpressed in ovarian, breast and prostate cancers. Moreover, it has been shown to play a role in regulating cell proliferation and migration, and to interact with RNA Polymerase II (RNAPII). Here, we find that backfolding of MVI regulates its ability to bind DNA and that a putative transcription co-activator NDP52 relieves the auto-inhibition of MVI to enable DNA binding. Additionally, we show that the MVI-NDP52 complex binds RNAPII, which is critical for transcription, and that depletion of NDP52 or MVI reduces steady-state mRNA levels. Lastly, we demonstrate that MVI directly interacts with nuclear receptors to drive expression of target genes, thereby suggesting a link to cell proliferation and migration. Overall, we suggest MVI may function as an auxiliary motor to drive transcription.
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Affiliation(s)
- Natalia Fili
- School of Biosciences, University of Kent, Canterbury, CT2 7NJ, UK
| | - Yukti Hari-Gupta
- School of Biosciences, University of Kent, Canterbury, CT2 7NJ, UK
| | - Ália Dos Santos
- School of Biosciences, University of Kent, Canterbury, CT2 7NJ, UK
| | - Alexander Cook
- School of Biosciences, University of Kent, Canterbury, CT2 7NJ, UK
| | - Simon Poland
- Randall Division of Cell and Molecular Biophysics, King's College London, Guys Campus, London, SE1 1UL, UK
| | - Simon M Ameer-Beg
- Randall Division of Cell and Molecular Biophysics, King's College London, Guys Campus, London, SE1 1UL, UK
| | - Maddy Parsons
- Randall Division of Cell and Molecular Biophysics, King's College London, Guys Campus, London, SE1 1UL, UK
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41
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Parisis N, Krasinska L, Harker B, Urbach S, Rossignol M, Camasses A, Dewar J, Morin N, Fisher D. Initiation of DNA replication requires actin dynamics and formin activity. EMBO J 2017; 36:3212-3231. [PMID: 28982779 DOI: 10.15252/embj.201796585] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Revised: 08/28/2017] [Accepted: 09/07/2017] [Indexed: 12/19/2022] Open
Abstract
Nuclear actin regulates transcriptional programmes in a manner dependent on its levels and polymerisation state. This dynamics is determined by the balance of nucleocytoplasmic shuttling, formin- and redox-dependent filament polymerisation. Here, using Xenopus egg extracts and human somatic cells, we show that actin dynamics and formins are essential for DNA replication. In proliferating cells, formin inhibition abolishes nuclear transport and initiation of DNA replication, as well as general transcription. In replicating nuclei from transcriptionally silent Xenopus egg extracts, we identified numerous actin regulators, and disruption of actin dynamics abrogates nuclear transport, preventing NLS (nuclear localisation signal)-cargo release from RanGTP-importin complexes. Nuclear formin activity is further required to promote loading of cyclin-dependent kinase (CDK) and proliferating cell nuclear antigen (PCNA) onto chromatin, as well as initiation and elongation of DNA replication. Therefore, actin dynamics and formins control DNA replication by multiple direct and indirect mechanisms.
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Affiliation(s)
- Nikolaos Parisis
- IGMM, CNRS Univ. Montpellier, Montpellier, France.,Laboratory of Functional Proteomics, INRA, Montpellier, France
| | | | | | - Serge Urbach
- Functional Proteomics Platform (FPP), Institute of Functional Genomics (IGF), CNRS UMR 5203 INSERM U661, Montpellier, France
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42
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Raz-Ben Aroush D, Ofer N, Abu-Shah E, Allard J, Krichevsky O, Mogilner A, Keren K. Actin Turnover in Lamellipodial Fragments. Curr Biol 2017; 27:2963-2973.e14. [PMID: 28966086 DOI: 10.1016/j.cub.2017.08.066] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 07/21/2017] [Accepted: 08/29/2017] [Indexed: 10/18/2022]
Abstract
Actin turnover is the central driving force underlying lamellipodial motility. The molecular components involved are largely known, and their properties have been studied extensively in vitro. However, a comprehensive picture of actin turnover in vivo is still missing. We focus on fragments from fish epithelial keratocytes, which are essentially stand-alone motile lamellipodia. The geometric simplicity of the fragments and the absence of additional actin structures allow us to characterize the spatiotemporal lamellipodial actin organization with unprecedented detail. We use fluorescence recovery after photobleaching, fluorescence correlation spectroscopy, and extraction experiments to show that about two-thirds of the lamellipodial actin diffuses in the cytoplasm with nearly uniform density, whereas the rest forms the treadmilling polymer network. Roughly a quarter of the diffusible actin pool is in filamentous form as diffusing oligomers, indicating that severing and debranching are important steps in the disassembly process generating oligomers as intermediates. The remaining diffusible actin concentration is orders of magnitude higher than the in vitro actin monomer concentration required to support the observed polymerization rates, implying that the majority of monomers are transiently kept in a non-polymerizable "reserve" pool. The actin network disassembles and reassembles throughout the lamellipodium within seconds, so the lamellipodial network turnover is local. The diffusible actin transport, on the other hand, is global: actin subunits typically diffuse across the entire lamellipodium before reassembling into the network. This combination of local network turnover and global transport of dissociated subunits through the cytoplasm makes actin transport robust yet rapidly adaptable and amenable to regulation.
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Affiliation(s)
- Dikla Raz-Ben Aroush
- Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Noa Ofer
- Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel; Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Enas Abu-Shah
- Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel; Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Jun Allard
- Department of Mathematics, Center for Complex Biological Systems and Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697, USA
| | - Oleg Krichevsky
- Physics Department and Ilse Kats Center for Nanoscience, Ben-Gurion University, Beer-Sheva 84105, Israel
| | - Alex Mogilner
- Courant Institute of Mathematical Sciences and Department of Biology, New York University, New York, NY 10012, USA.
| | - Kinneret Keren
- Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel; Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa 32000, Israel; Network Biology Research Laboratories, Technion-Israel Institute of Technology, Haifa 32000, Israel.
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43
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Sen B, Uzer G, Samsonraj RM, Xie Z, McGrath C, Styner M, Dudakovic A, van Wijnen AJ, Rubin J. Intranuclear Actin Structure Modulates Mesenchymal Stem Cell Differentiation. Stem Cells 2017; 35:1624-1635. [PMID: 28371128 DOI: 10.1002/stem.2617] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Revised: 02/19/2017] [Accepted: 03/10/2017] [Indexed: 01/05/2023]
Abstract
Actin structure contributes to physiologic events within the nucleus to control mesenchymal stromal cell (MSC) differentiation. Continuous cytochalasin D (Cyto D) disruption of the MSC actin cytoskeleton leads to osteogenic or adipogenic differentiation, both requiring mass transfer of actin into the nucleus. Cyto D remains extranuclear, thus intranuclear actin polymerization is potentiated by actin transfer: we asked whether actin structure affects differentiation. We show that secondary actin filament branching via the Arp2/3 complex is required for osteogenesis and that preventing actin branching stimulates adipogenesis, as shown by expression profiling of osteogenic and adipogenic biomarkers and unbiased RNA-seq analysis. Mechanistically, Cyto D activates osteoblast master regulators (e.g., Runx2, Sp7, Dlx5) and novel coregulated genes (e.g., Atoh8, Nr4a3, Slfn5). Formin-induced primary actin filament formation is critical for Arp2/3 complex recruitment: osteogenesis is prevented by silencing of the formin mDia1, but not its paralog mDia2. Furthermore, while inhibition of actin, branching is a potent adipogenic stimulus, silencing of either mDia1 or mDia2 blocks adipogenic gene expression. We propose that mDia1, which localizes in the cytoplasm of multipotential MSCs and traffics into the nucleus after cytoskeletal disruption, joins intranuclear mDia2 to facilitate primary filament formation before mediating subsequent branching via Arp2/3 complex recruitment. The resulting intranuclear branched actin network specifies osteogenic differentiation, while actin polymerization in the absence of Arp2/3 complex-mediated secondary branching causes adipogenic differentiation. Stem Cells 2017;35:1624-1635.
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Affiliation(s)
- Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Gunes Uzer
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA.,Department of Mechanical/Biomedical Engineering, Boise State University, Boise, Idaho, USA
| | - Rebekah M Samsonraj
- Department of Orthopedic Surgery and Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Zhihui Xie
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Cody McGrath
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Maya Styner
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Amel Dudakovic
- Department of Orthopedic Surgery and Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Andre J van Wijnen
- Department of Orthopedic Surgery and Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota, USA
| | - Janet Rubin
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA.,Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina, USA
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44
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Abstract
Although most people still associate actin mainly with the cytoskeleton, several lines of evidence, with the earliest studies dating back to decades ago, have emphasized the importance of actin also inside the cell nucleus. Actin has been linked to many gene expression processes from gene activation to chromatin remodeling, but also to maintenance of genomic integrity and intranuclear movement of chromosomes and chromosomal loci. Recent advances in visualizing different forms and dynamic properties of nuclear actin have clearly advanced our understanding of the basic concepts by which actin operates in the nucleus. In this chapter we address the different breakthroughs in nuclear actin studies, as well as discuss the regulation nuclear actin and the importance of nuclear actin dynamics in relation to its different nuclear functions. Our aim is to highlight the fact that actin should be considered as an essential component of the cell nucleus, and its nuclear actions should be taken into account also in experiments on cytoplasmic actin networks.
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Affiliation(s)
- Tiina Viita
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, 56, Helsinki, Finland
| | - Maria K Vartiainen
- Program in Cell and Molecular Biology, Institute of Biotechnology, University of Helsinki, 56, Helsinki, Finland.
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45
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Kapustina M, Read TA, Vitriol EA. Simultaneous quantification of actin monomer and filament dynamics with modeling-assisted analysis of photoactivation. J Cell Sci 2016; 129:4633-4643. [PMID: 27831495 PMCID: PMC5201019 DOI: 10.1242/jcs.194670] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 11/02/2016] [Indexed: 01/30/2023] Open
Abstract
Photoactivation allows one to pulse-label molecules and obtain quantitative data about their behavior. We have devised a new modeling-based analysis for photoactivatable actin experiments that simultaneously measures properties of monomeric and filamentous actin in a three-dimensional cellular environment. We use this method to determine differences in the dynamic behavior of β- and γ-actin isoforms, showing that both inhabit filaments that depolymerize at equal rates but that β-actin exists in a higher monomer-to-filament ratio. We also demonstrate that cofilin (cofilin 1) equally accelerates depolymerization of filaments made from both isoforms, but is only required to maintain the β-actin monomer pool. Finally, we used modeling-based analysis to assess actin dynamics in axon-like projections of differentiating neuroblastoma cells, showing that the actin monomer concentration is significantly depleted as the axon develops. Importantly, these results would not have been obtained using traditional half-time analysis. Given that parameters of the publicly available modeling platform can be adjusted to suit the experimental system of the user, this method can easily be used to quantify actin dynamics in many different cell types and subcellular compartments.
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Affiliation(s)
- Maryna Kapustina
- Department of Cell Biology and Physiology, School of Medicine, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Tracy-Ann Read
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL 32610, USA
| | - Eric A Vitriol
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, FL 32610, USA
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46
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Serebryannyy LA, Yuen M, Parilla M, Cooper ST, de Lanerolle P. The Effects of Disease Models of Nuclear Actin Polymerization on the Nucleus. Front Physiol 2016; 7:454. [PMID: 27774069 PMCID: PMC5053997 DOI: 10.3389/fphys.2016.00454] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 09/21/2016] [Indexed: 01/09/2023] Open
Abstract
Actin plays a crucial role in regulating multiple processes within the nucleus, including transcription and chromatin organization. However, the polymerization state of nuclear actin remains controversial, and there is no evidence for persistent actin filaments in a normal interphase nucleus. Further, several disease pathologies are characterized by polymerization of nuclear actin into stable filaments or rods. These include filaments that stain with phalloidin, resulting from point mutations in skeletal α-actin, detected in the human skeletal disease intranuclear rod myopathy, and cofilin/actin rods that form in response to cellular stressors like heatshock. To further elucidate the effects of these pathological actin structures, we examined the nucleus in both cell culture models as well as isolated human tissues. We find these actin structures alter the distribution of both RNA polymerase II and chromatin. Our data suggest that nuclear actin filaments result in disruption of nuclear organization, which may contribute to the disease pathology.
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Affiliation(s)
- Leonid A Serebryannyy
- Department of Physiology and Biophysics, University of Illinois at Chicago Chicago, IL, USA
| | - Michaela Yuen
- Institute for Neuroscience and Muscle Research, Kids Research Institute, The Children's Hospital at WestmeadSydney, NSW, Australia; Faculty of Medicine, Discipline of Pediatrics and Child Health, University of SydneySydney, NSW, Australia
| | - Megan Parilla
- Department of Physiology and Biophysics, University of Illinois at Chicago Chicago, IL, USA
| | - Sandra T Cooper
- Institute for Neuroscience and Muscle Research, Kids Research Institute, The Children's Hospital at WestmeadSydney, NSW, Australia; Faculty of Medicine, Discipline of Pediatrics and Child Health, University of SydneySydney, NSW, Australia
| | - Primal de Lanerolle
- Department of Physiology and Biophysics, University of Illinois at Chicago Chicago, IL, USA
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47
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Sharili AS, Kenny FN, Vartiainen MK, Connelly JT. Nuclear actin modulates cell motility via transcriptional regulation of adhesive and cytoskeletal genes. Sci Rep 2016; 6:33893. [PMID: 27650314 PMCID: PMC5030641 DOI: 10.1038/srep33893] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2016] [Accepted: 09/05/2016] [Indexed: 01/08/2023] Open
Abstract
The actin cytoskeleton is a classic biomechanical mediator of cell migration. While it is known that actin also shuttles in and out of the nucleus, its functions within this compartment remain poorly understood. In this study, we investigated how nuclear actin regulates keratinocyte gene expression and cell behavior. Gene expression profiling of normal HaCaT keratinocytes compared to HaCaTs over-expressing wild-type β-actin or β-actin tagged with a nuclear localization sequence (NLS-actin), identified multiple adhesive and cytoskeletal genes, such as MYL9, ITGB1, and VCL, which were significantly down-regulated in keratinocytes with high levels of nuclear actin. In addition, genes associated with transcriptional regulation and apoptosis were up-regulated in cells over expressing NLS-actin. Functionally, accumulation of actin in the nucleus altered cytoskeletal and focal adhesion organization and inhibited cell motility. Exclusion of endogenous actin from the nucleus by knocking down Importin 9 reversed this phenotype and enhanced cell migration. Based on these findings, we conclude that the level of actin in the nucleus is a transcriptional regulator for tuning keratinocyte migration.
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Affiliation(s)
- Amir S. Sharili
- Centre for Cell Biology and Cutaneous Research, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, U.K.
| | - Fiona N. Kenny
- Centre for Cell Biology and Cutaneous Research, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, U.K.
| | | | - John T. Connelly
- Centre for Cell Biology and Cutaneous Research, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AT, U.K.
- Institute of Bioengineering, Queen Mary University of London, London E1 2AT, U.K.
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48
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Kelpsch DJ, Groen CM, Fagan TN, Sudhir S, Tootle TL. Fascin regulates nuclear actin during Drosophila oogenesis. Mol Biol Cell 2016; 27:2965-79. [PMID: 27535426 PMCID: PMC5042582 DOI: 10.1091/mbc.e15-09-0634] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 08/02/2016] [Indexed: 01/15/2023] Open
Abstract
Study of Drosophila oogenesis reveals that the nuclear localization of actin is controlled by both development and Fascin. Fascin regulates both endogenous nuclear actin and ectopic nuclear actin rod formation by controlling Cofilin. Drosophila oogenesis provides a developmental system with which to study nuclear actin. During Stages 5–9, nuclear actin levels are high in the oocyte and exhibit variation within the nurse cells. Cofilin and Profilin, which regulate the nuclear import and export of actin, also localize to the nuclei. Expression of GFP-tagged Actin results in nuclear actin rod formation. These findings indicate that nuclear actin must be tightly regulated during oogenesis. One factor mediating this regulation is Fascin. Overexpression of Fascin enhances nuclear GFP-Actin rod formation, and Fascin colocalizes with the rods. Loss of Fascin reduces, whereas overexpression of Fascin increases, the frequency of nurse cells with high levels of nuclear actin, but neither alters the overall nuclear level of actin within the ovary. These data suggest that Fascin regulates the ability of specific cells to accumulate nuclear actin. Evidence indicates that Fascin positively regulates nuclear actin through Cofilin. Loss of Fascin results in decreased nuclear Cofilin. In addition, Fascin and Cofilin genetically interact, as double heterozygotes exhibit a reduction in the number of nurse cells with high nuclear actin levels. These findings are likely applicable beyond Drosophila follicle development, as the localization and functions of Fascin and the mechanisms regulating nuclear actin are widely conserved.
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Affiliation(s)
- Daniel J Kelpsch
- Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA 52242
| | - Christopher M Groen
- Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA 52242
| | - Tiffany N Fagan
- Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA 52242
| | - Sweta Sudhir
- Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA 52242
| | - Tina L Tootle
- Anatomy and Cell Biology, University of Iowa Carver College of Medicine, Iowa City, IA 52242
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49
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Serebryannyy LA, Parilla M, Annibale P, Cruz CM, Laster K, Gratton E, Kudryashov D, Kosak ST, Gottardi CJ, de Lanerolle P. Persistent nuclear actin filaments inhibit transcription by RNA polymerase II. J Cell Sci 2016; 129:3412-25. [PMID: 27505898 DOI: 10.1242/jcs.195867] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 07/27/2016] [Indexed: 12/26/2022] Open
Abstract
Actin is abundant in the nucleus and it is clear that nuclear actin has important functions. However, mystery surrounds the absence of classical actin filaments in the nucleus. To address this question, we investigated how polymerizing nuclear actin into persistent nuclear actin filaments affected transcription by RNA polymerase II. Nuclear filaments impaired nuclear actin dynamics by polymerizing and sequestering nuclear actin. Polymerizing actin into stable nuclear filaments disrupted the interaction of actin with RNA polymerase II and correlated with impaired RNA polymerase II localization, dynamics, gene recruitment, and reduced global transcription and cell proliferation. Polymerizing and crosslinking nuclear actin in vitro similarly disrupted the actin-RNA-polymerase-II interaction and inhibited transcription. These data rationalize the general absence of stable actin filaments in mammalian somatic nuclei. They also suggest a dynamic pool of nuclear actin is required for the proper localization and activity of RNA polymerase II.
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Affiliation(s)
- Leonid A Serebryannyy
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Megan Parilla
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Paolo Annibale
- Laboratory of Fluorescence Dynamics, University of California Irvine, Irvine, CA 92697, USA
| | - Christina M Cruz
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Kyle Laster
- Department of Cell and Molecular Biology, Northwestern University, Chicago, IL 60611, USA
| | - Enrico Gratton
- Laboratory of Fluorescence Dynamics, University of California Irvine, Irvine, CA 92697, USA
| | - Dmitri Kudryashov
- Department of Chemistry and Biochemistry, Ohio State University, Columbus, OH 43210, USA
| | - Steven T Kosak
- Department of Cell and Molecular Biology, Northwestern University, Chicago, IL 60611, USA
| | - Cara J Gottardi
- Department of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Primal de Lanerolle
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA
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50
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Bhosle VK, Rivera JC, Zhou TE, Omri S, Sanchez M, Hamel D, Zhu T, Rouget R, Rabea AA, Hou X, Lahaie I, Ribeiro-da-Silva A, Chemtob S. Nuclear localization of platelet-activating factor receptor controls retinal neovascularization. Cell Discov 2016; 2:16017. [PMID: 27462464 PMCID: PMC4941644 DOI: 10.1038/celldisc.2016.17] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 05/11/2016] [Indexed: 02/08/2023] Open
Abstract
Platelet-activating factor (PAF) is a pleiotropic phospholipid with proinflammatory, procoagulant and angiogenic actions on the vasculature. We and others have reported the presence of PAF receptor (Ptafr) at intracellular sites such as the nucleus. However, mechanisms of localization and physiologic functions of intracellular Ptafr remain poorly understood. We hereby identify the importance of C-terminal motif of the receptor and uncover novel roles of Rab11a GTPase and importin-5 in nuclear translocation of Ptafr in primary human retinal microvascular endothelial cells. Nuclear localization of Ptafr is independent of exogenous PAF stimulation as well as intracellular PAF biosynthesis. Moreover, nuclear Ptafr is responsible for the upregulation of unique set of growth factors, including vascular endothelial growth factor, in vitro and ex vivo. We further corroborate the intracrine PAF signaling, resulting in angiogenesis in vivo, using Ptafr antagonists with distinct plasma membrane permeability. Collectively, our findings show that nuclear Ptafr translocates in an agonist-independent manner, and distinctive functions of Ptafr based on its cellular localization point to another dimension needed for pharmacologic selectivity of drugs.
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Affiliation(s)
- Vikrant K Bhosle
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada; CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Ophthalmology, Research Centre of Hôpital Maisonneuve-Rosemont, University of Montréal, Montréal, QC, Canada
| | - José Carlos Rivera
- CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Ophthalmology, Research Centre of Hôpital Maisonneuve-Rosemont, University of Montréal, Montréal, QC, Canada
| | - Tianwei Ellen Zhou
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada; CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Ophthalmology, Research Centre of Hôpital Maisonneuve-Rosemont, University of Montréal, Montréal, QC, Canada; Department of Medicine, McGill University Health Center, Montreal, QC, Canada
| | - Samy Omri
- CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Ophthalmology, Research Centre of Hôpital Maisonneuve-Rosemont, University of Montréal, Montréal, QC, Canada
| | - Melanie Sanchez
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada; CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Ophthalmology, Research Centre of Hôpital Maisonneuve-Rosemont, University of Montréal, Montréal, QC, Canada
| | - David Hamel
- CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Pharmacology, University of Montréal, Montréal, QC, Canada
| | - Tang Zhu
- CHU Sainte Justine Hospital Research Centre, University of Montréal , Montréal, QC, Canada
| | - Raphael Rouget
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada; CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada
| | - Areej Al Rabea
- Experimental Surgery, Montreal General Hospital, McGill University , Montréal, QC, Canada
| | - Xin Hou
- CHU Sainte Justine Hospital Research Centre, University of Montréal , Montréal, QC, Canada
| | - Isabelle Lahaie
- CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Ophthalmology, Research Centre of Hôpital Maisonneuve-Rosemont, University of Montréal, Montréal, QC, Canada
| | - Alfredo Ribeiro-da-Silva
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada; Alan Edwards Centre for Research on Pain, McGill University, Montréal, QC, Canada; Department of Anatomy and Cell Biology, McGill University, Montréal, QC, Canada
| | - Sylvain Chemtob
- Department of Pharmacology and Therapeutics, McGill University, Montréal, QC, Canada; CHU Sainte Justine Hospital Research Centre, University of Montréal, Montréal, QC, Canada; Department of Ophthalmology, Research Centre of Hôpital Maisonneuve-Rosemont, University of Montréal, Montréal, QC, Canada; Department of Pharmacology, University of Montréal, Montréal, QC, Canada; Departments of Pediatrics and Ophthalmology, Faculty of Medicine, University of Montréal, Montréal, QC, Canada
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