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Single-molecule imaging of the transcription factor SRF reveals prolonged chromatin-binding kinetics upon cell stimulation. Proc Natl Acad Sci U S A 2018; 116:880-889. [PMID: 30598445 PMCID: PMC6338867 DOI: 10.1073/pnas.1812734116] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
How transcription factors (TFs) activate transcription is a long-standing but still unsolved question. We analyzed serum response factor (SRF), a stimulus-responsive TF mediating immediate early gene (IEG) and cytoskeletal gene expression at single-molecule resolution. Cell stimulation enhanced SRF activity by increasing the number of long chromatin-associated SRF molecules in an oscillating pattern. Further, stimulation enhanced the SRF chromatin residence time, and SRF binding events segregated into three distinct residence time regimes (short, intermediate, and long bound). In summary, our single-molecule imaging study reveals highly dynamic and diverse SRF interactions with DNA. Thus, cell stimulation regulates TF activity by several interconnected mechanisms including nucleus−cytoplasm shuttling, TF phosphorylation, cofactor recruitment, and extension of chromatin residence time and enhancing chromatin-bound TF numbers. Serum response factor (SRF) mediates immediate early gene (IEG) and cytoskeletal gene expression programs in almost any cell type. So far, SRF transcriptional dynamics have not been investigated at single-molecule resolution. We provide a study of single Halo-tagged SRF molecules in fibroblasts and primary neurons. In both cell types, individual binding events of SRF molecules segregated into three chromatin residence time regimes, short, intermediate, and long binding, indicating a cell type-independent SRF property. The chromatin residence time of the long bound fraction was up to 1 min in quiescent cells and significantly increased upon stimulation. Stimulation also enhanced the long bound SRF fraction at specific timepoints (20 and 60 min) in both cell types. These peaks correlated with activation of the SRF cofactors MRTF-A and MRTF-B (myocardin-related transcription factors). Interference with signaling pathways and cofactors demonstrated modulation of SRF chromatin occupancy by actin signaling, MAP kinases, and MRTFs.
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52
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Liu C, Zhu R, Mao Y. 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] [Grants] [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.
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Affiliation(s)
- Chenshu Liu
- Department of Pathology and Cell Biology, Columbia University Vagelos College of Physicians and Surgeons, 630 W 168(th) Street, New York, NY 10032, USA.
| | - Ruijun Zhu
- Department of Pathology and Cell Biology, Columbia University Vagelos College of Physicians and Surgeons, 630 W 168(th) Street, New York, NY 10032, USA
| | - Yinghui Mao
- Department of Pathology and Cell Biology, Columbia University Vagelos College of Physicians and Surgeons, 630 W 168(th) Street, New York, NY 10032, USA.
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53
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Kluge F, Weissbach J, Weber A, Stradal T, Posern G. Regulation of MRTF-A by JMY via a nucleation-independent mechanism. Cell Commun Signal 2018; 16:86. [PMID: 30463620 PMCID: PMC6249979 DOI: 10.1186/s12964-018-0299-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 11/13/2018] [Indexed: 11/23/2022] Open
Abstract
Background MRTF-A (myocardin-related transcription factor A) is a coactivator for SRF-mediated gene expression. The activity of MRTF-A is critically dependent on the dissociation of G-actin from N-terminal RPEL motifs. MRTF-SRF induction often correlates with enhanced polymerization of F-actin. Here we investigate MRTF regulation by the multifunctional JMY protein, which contains three WASP/verprolin homology 2 (WH2/V) domains and facilitates Arp2/3-dependent and -independent actin nucleation. Methods Co-immunoprecipitation experiments, immunofluorescence and luciferase reporter assays were combined with selective inhibitors to investigate the effect of JMY and its domains on MRTF-A in NIH 3 T3 mouse fibroblasts. Results JMY induced MRTF-A transcriptional activity and enhanced its nuclear translocation. Unexpectedly, MRTF-A was hyperactivated when the Arp2/3-recruiting CA region of JMY was deleted or mutated, suggesting an autoinhibitory mechanism for full-length JMY. Moreover, isolated WH2/V domains which are unable to nucleate actin were sufficient for nuclear accumulation and SRF activation. Recombinant WH2/V regions of JMY biochemically competed with MRTF-A for actin binding. Activation of MRTF-A by JMY was unaffected by Arp3 knockdown, by an Arp2/3 inhibitor, and by latrunculin which disassembles cellular F-actin. Restriction of JMY to the nucleus abrogated its MRTF-A activation. Finally, JMY RNAi reduced basal and stimulated transcriptional activation via MRTF-A. Conclusions Our results suggest that JMY activates MRTF-SRF independently of F-actin via WH2/V-mediated competition with the RPEL region for G-actin binding in the cytoplasm. Furthermore, the C-terminal region facilitates an autoinhibitory effect on full-length JMY, possibly by intramolecular folding.
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Affiliation(s)
- Franziska Kluge
- Institute for Physiological Chemistry, Medical Faculty, Martin Luther University Halle-Wittenberg, 06114, Halle (Saale), Germany
| | - Julia Weissbach
- Institute for Physiological Chemistry, Medical Faculty, Martin Luther University Halle-Wittenberg, 06114, Halle (Saale), Germany
| | - Anja Weber
- Institute for Physiological Chemistry, Medical Faculty, Martin Luther University Halle-Wittenberg, 06114, Halle (Saale), Germany
| | - Theresia Stradal
- Department of Cell Biology, Helmholtz Centre for Infection Research, 38124, Braunschweig, Germany
| | - Guido Posern
- Institute for Physiological Chemistry, Medical Faculty, Martin Luther University Halle-Wittenberg, 06114, Halle (Saale), Germany.
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Pei H, Hu W, Guo Z, Chen H, Ma J, Mao W, Li B, Wang A, Wan J, Zhang J, Nie J, Zhou G, Hei TK. Long Noncoding RNA CRYBG3 Blocks Cytokinesis by Directly Binding G-Actin. Cancer Res 2018; 78:4563-4572. [PMID: 29934435 PMCID: PMC6095725 DOI: 10.1158/0008-5472.can-18-0988] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 05/23/2018] [Accepted: 06/15/2018] [Indexed: 01/05/2023]
Abstract
The dynamic interchange between monomeric globular actin (G-actin) and polymeric filamentous actin filaments (F-actin) is fundamental and essential to many cellular processes, including cytokinesis and maintenance of genomic stability. Here, we report that the long noncoding RNA LNC CRYBG3 directly binds G-actin to inhibit its polymerization and formation of contractile rings, resulting in M-phase cell arrest. Knockdown of LNC CRYBG3 in tumor cells enhanced their malignant phenotypes. Nucleotide sequence 228-237 of the full-length LNC CRYBG3 and the ser14 domain of β-actin is essential for their interaction, and mutation of either of these sites abrogated binding of LNC CRYBG3 to G-actin. Binding of LNC CRYBG3 to G-actin blocked nuclear localization of MAL, which consequently kept serum response factor (SRF) away from the promoter region of several immediate early genes, including JUNB and Arp3, which are necessary for cellular proliferation, tumor growth, adhesion, movement, and metastasis. These findings reveal a novel lncRNA-actin-MAL-SRF pathway and highlight LNC CRYBG3 as a means to block cytokinesis and to treat cancer by targeting the actin cytoskeleton.Significance: Identification of the long noncoding RNA LNC CRYBG3 as a mediator of microfilament disorganization marks it as a novel therapeutic antitumor strategy. Cancer Res; 78(16); 4563-72. ©2018 AACR.
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Affiliation(s)
- Hailong Pei
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou, China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou, China
| | - Wentao Hu
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou, China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou, China
| | - Ziyang Guo
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou, China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou, China
| | - Huaiyuan Chen
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou, China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou, China
| | - Ji Ma
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou, China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou, China
| | - Weidong Mao
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou, China
- The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Bingyan Li
- Medical College of Soochow University, Suzhou, China
| | - Aiqing Wang
- Medical College of Soochow University, Suzhou, China
| | - Jianmei Wan
- Medical College of Soochow University, Suzhou, China
| | - Jian Zhang
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou, China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou, China
| | - Jing Nie
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou, China
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou, China
| | - Guangming Zhou
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou, China.
- Collaborative Innovation Center of Radiological Medicine of Jiangsu Higher Education Institutions, Suzhou, China
| | - Tom K Hei
- State Key Laboratory of Radiation Medicine and Protection, School of Radiation Medicine and Protection, Medical College of Soochow University, Suzhou, China.
- Center for Radiological Research, College of Physician and Surgeons, Columbia University, New York, New York
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Gegenfurtner FA, Jahn B, Wagner H, Ziegenhain C, Enard W, Geistlinger L, Rädler JO, Vollmar AM, Zahler S. Micropatterning as a tool to identify regulatory triggers and kinetics of actin-mediated endothelial mechanosensing. J Cell Sci 2018; 131:jcs.212886. [PMID: 29724912 DOI: 10.1242/jcs.212886] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 04/25/2018] [Indexed: 12/11/2022] Open
Abstract
Developmental processes, such as angiogenesis, are associated with a constant remodeling of the actin cytoskeleton in response to different mechanical stimuli. The mechanosensitive transcription factors MRTF-A (MKL1) and YAP (also known as YAP1) are important mediators of this challenging adaptation process. However, it is as yet unknown whether both pathways respond in an identical or in a divergent manner to a given microenvironmental guidance cue. Here, we use a micropatterning approach to dissect single aspects of cellular behavior in a spatiotemporally controllable setting. Using the exemplary process of angiogenesis, we show that cell-cell contacts and adhesive surface area are shared regulatory parameters of MRTF and YAP on rigid 2D surfaces. By analyzing MRTF and YAP under laminar flow conditions and during cell migration on dumbbell-shaped microstructures, we demonstrate that they exhibit different translocation kinetics. In conclusion, our work promotes the application of micropatterning techniques as a cell biological tool to study mechanosensitive signaling in the context of angiogenesis.
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Affiliation(s)
- Florian A Gegenfurtner
- Ludwig-Maximilians-University Munich, Department of Pharmacy, Center for Drug Research, 81377 Munich, Germany
| | - Berenice Jahn
- Ludwig-Maximilians-University Munich, Department of Pharmacy, Center for Drug Research, 81377 Munich, Germany
| | - Helga Wagner
- ibidi GmbH, Am Klopferspitz 19, 82152 Martinsried, Germany
| | - Christoph Ziegenhain
- Ludwig-Maximilians-University Munich, Department of Biology II, Anthropology and Human Genomics, 82152 Martinsried, Germany
| | - Wolfgang Enard
- Ludwig-Maximilians-University Munich, Department of Biology II, Anthropology and Human Genomics, 82152 Martinsried, Germany
| | - Ludwig Geistlinger
- Ludwig-Maximilians-University Munich, Institute for Informatics, Teaching and Research Unit Bioinformatics, 80333 Munich, Germany
| | - Joachim O Rädler
- Ludwig-Maximilians-University Munich, Faculty of Physics, Soft Condensed Matter Group, 80539 Munich, Germany
| | - Angelika M Vollmar
- Ludwig-Maximilians-University Munich, Department of Pharmacy, Center for Drug Research, 81377 Munich, Germany
| | - Stefan Zahler
- Ludwig-Maximilians-University Munich, Department of Pharmacy, Center for Drug Research, 81377 Munich, Germany
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56
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Bar-Yosef H, Gildor T, Ramírez-Zavala B, Schmauch C, Weissman Z, Pinsky M, Naddaf R, Morschhäuser J, Arkowitz RA, Kornitzer D. A Global Analysis of Kinase Function in Candida albicans Hyphal Morphogenesis Reveals a Role for the Endocytosis Regulator Akl1. Front Cell Infect Microbiol 2018; 8:17. [PMID: 29473018 PMCID: PMC5809406 DOI: 10.3389/fcimb.2018.00017] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 01/12/2018] [Indexed: 11/22/2022] Open
Abstract
The human pathogenic fungus Candida albicans can switch between yeast and hyphal morphologies as a function of environmental conditions and cellular physiology. The yeast-to-hyphae morphogenetic switch is activated by well-established, kinase-based signal transduction pathways that are induced by extracellular stimuli. In order to identify possible inhibitory pathways of the yeast-to-hyphae transition, we interrogated a collection of C. albicans protein kinases and phosphatases ectopically expressed under the regulation of the TETon promoter. Proportionately more phosphatases than kinases were identified that inhibited hyphal morphogenesis, consistent with the known role of protein phosphorylation in hyphal induction. Among the kinases, we identified AKL1 as a gene that significantly suppressed hyphal morphogenesis in serum. Akl1 specifically affected hyphal elongation rather than initiation: overexpression of AKL1 repressed hyphal growth, and deletion of AKL1 resulted in acceleration of the rate of hyphal elongation. Akl1 suppressed fluid-phase endocytosis, probably via Pan1, a putative clathrin-mediated endocytosis scaffolding protein. In the absence of Akl1, the Pan1 patches were delocalized from the sub-apical region, and fluid-phase endocytosis was intensified. These results underscore the requirement of an active endocytic pathway for hyphal morphogenesis. Furthermore, these results suggest that under standard conditions, endocytosis is rate-limiting for hyphal elongation.
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Affiliation(s)
- Hagit Bar-Yosef
- B. Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Rappaport Institute for Research in the Medical Sciences, Haifa, Israel
| | - Tsvia Gildor
- B. Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Rappaport Institute for Research in the Medical Sciences, Haifa, Israel
| | | | - Christian Schmauch
- Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institute Biology Valrose, Université Côte d'Azur, Nice, France
| | - Ziva Weissman
- B. Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Rappaport Institute for Research in the Medical Sciences, Haifa, Israel
| | - Mariel Pinsky
- B. Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Rappaport Institute for Research in the Medical Sciences, Haifa, Israel
| | - Rawi Naddaf
- B. Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Rappaport Institute for Research in the Medical Sciences, Haifa, Israel
| | - Joachim Morschhäuser
- Institut für Molekulare Infektionsbiologie, Universität Würzburg, Würzburg, Germany
| | - Robert A Arkowitz
- Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Institute Biology Valrose, Université Côte d'Azur, Nice, France
| | - Daniel Kornitzer
- B. Rappaport Faculty of Medicine, Technion - Israel Institute of Technology, Rappaport Institute for Research in the Medical Sciences, Haifa, Israel
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Jonchère V, Alqadri N, Herbert J, Dodgson L, Mason D, Messina G, Falciani F, Bennett D. Transcriptional responses to hyperplastic MRL signalling in Drosophila. Open Biol 2017; 7:rsob.160306. [PMID: 28148822 PMCID: PMC5356444 DOI: 10.1098/rsob.160306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Accepted: 01/04/2017] [Indexed: 12/19/2022] Open
Abstract
Recent work has implicated the actin cytoskeleton in tissue size control and tumourigenesis, but how changes in actin dynamics contribute to hyperplastic growth is still unclear. Overexpression of Pico, the only Drosophila Mig-10/RIAM/Lamellipodin adapter protein family member, has been linked to tissue overgrowth via its effect on the myocardin-related transcription factor (Mrtf), an F-actin sensor capable of activating serum response factor (SRF). Transcriptional changes induced by acute Mrtf/SRF signalling have been largely linked to actin biosynthesis and cytoskeletal regulation. However, by RNA profiling, we find that the common response to chronic mrtf and pico overexpression in wing discs was upregulation of ribosome protein and mitochondrial genes, which are conserved targets for Mrtf/SRF and are known growth drivers. Consistent with their ability to induce a common transcriptional response and activate SRF signalling in vitro, we found that both pico and mrtf stimulate expression of an SRF-responsive reporter gene in wing discs. In a functional genetic screen, we also identified deterin, which encodes Drosophila Survivin, as a putative Mrtf/SRF target that is necessary for pico-mediated tissue overgrowth by suppressing proliferation-associated cell death. Taken together, our findings raise the possibility that distinct targets of Mrtf/SRF may be transcriptionally induced depending on the duration of upstream signalling.
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Affiliation(s)
- Vincent Jonchère
- Department of Biochemistry, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Nada Alqadri
- Department of Biochemistry, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - John Herbert
- Centre for Computational Biology and Modelling (CCBM), Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Lauren Dodgson
- Department of Biochemistry, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - David Mason
- Centre for Cell Imaging, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Giovanni Messina
- Department of Biochemistry, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Francesco Falciani
- Centre for Computational Biology and Modelling (CCBM), Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Daimark Bennett
- Department of Biochemistry, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK .,Centre for Cell Imaging, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
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58
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Baarlink C, Plessner M, Sherrard A, Morita K, Misu S, Virant D, Kleinschnitz EM, Harniman R, Alibhai D, Baumeister S, Miyamoto K, Endesfelder U, Kaidi A, Grosse R. A transient pool of nuclear F-actin at mitotic exit controls chromatin organization. Nat Cell Biol 2017; 19:1389-1399. [PMID: 29131140 DOI: 10.1038/ncb3641] [Citation(s) in RCA: 137] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 10/05/2017] [Indexed: 12/13/2022]
Abstract
Re-establishment of nuclear structure and chromatin organization after cell division is integral for genome regulation or development and is frequently altered during cancer progression. The mechanisms underlying chromatin expansion in daughter cells remain largely unclear. Here, we describe the transient formation of nuclear actin filaments (F-actin) during mitotic exit. These nuclear F-actin structures assemble in daughter cell nuclei and undergo dynamic reorganization to promote nuclear protrusions and volume expansion throughout early G1 of the cell cycle. Specific inhibition of this nuclear F-actin assembly impaired nuclear expansion and chromatin decondensation after mitosis and during early mouse embryonic development. Biochemical screening for mitotic nuclear F-actin interactors identified the actin-disassembling factor cofilin-1. Optogenetic regulation of cofilin-1 revealed its critical role for controlling timing, turnover and dynamics of F-actin assembly inside daughter cell nuclei. Our findings identify a cell-cycle-specific and spatiotemporally controlled form of nuclear F-actin that reorganizes the mammalian nucleus after mitosis.
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Affiliation(s)
- Christian Baarlink
- Institute of Pharmacology, BPC Marburg, University of Marburg, Karl-von-Frisch-Str. 1, 35043 Marburg, Germany
| | - Matthias Plessner
- Institute of Pharmacology, BPC Marburg, University of Marburg, Karl-von-Frisch-Str. 1, 35043 Marburg, Germany
| | - Alice Sherrard
- School of Cellular and Molecular Medicine, Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Kohtaro Morita
- Faculty of Biology-Oriented Science and Technology, Kindai University, 930 Nishimitani, Wakayama 649-6493, Japan
| | - Shinji Misu
- Faculty of Biology-Oriented Science and Technology, Kindai University, 930 Nishimitani, Wakayama 649-6493, Japan
| | - David Virant
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch-Str. 16, 35043 Marburg, Germany
| | - Eva-Maria Kleinschnitz
- Institute of Pharmacology, BPC Marburg, University of Marburg, Karl-von-Frisch-Str. 1, 35043 Marburg, Germany
| | - Robert Harniman
- Electron Microscopy Unit, School of Chemistry, Biomedical Sciences, University of Bristol, Bristol BS8 1TS, UK
| | - Dominic Alibhai
- Wolfson Bioimaging Facility, University of Bristol, Bristol BS8 1TD, UK
| | - Stefan Baumeister
- Protein Analytics, Faculty of Biology, University of Marburg, Karl-von-Frisch-Str. 8, 35043 Marburg, Germany
| | - Kei Miyamoto
- Faculty of Biology-Oriented Science and Technology, Kindai University, 930 Nishimitani, Wakayama 649-6493, Japan
| | - Ulrike Endesfelder
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology and LOEWE Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch-Str. 16, 35043 Marburg, Germany
| | - Abderrahmane Kaidi
- School of Cellular and Molecular Medicine, Biomedical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, UK
| | - Robert Grosse
- Institute of Pharmacology, BPC Marburg, University of Marburg, Karl-von-Frisch-Str. 1, 35043 Marburg, Germany
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59
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Rupp T, Langlois B, Koczorowska MM, Radwanska A, Sun Z, Hussenet T, Lefebvre O, Murdamoothoo D, Arnold C, Klein A, Biniossek ML, Hyenne V, Naudin E, Velazquez-Quesada I, Schilling O, Van Obberghen-Schilling E, Orend G. Tenascin-C Orchestrates Glioblastoma Angiogenesis by Modulation of Pro- and Anti-angiogenic Signaling. Cell Rep 2017; 17:2607-2619. [PMID: 27926865 DOI: 10.1016/j.celrep.2016.11.012] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Revised: 09/22/2016] [Accepted: 10/31/2016] [Indexed: 12/21/2022] Open
Abstract
High expression of the extracellular matrix component tenascin-C in the tumor microenvironment correlates with decreased patient survival. Tenascin-C promotes cancer progression and a disrupted tumor vasculature through an unclear mechanism. Here, we examine the angiomodulatory role of tenascin-C. We find that direct contact of endothelial cells with tenascin-C disrupts actin polymerization, resulting in cytoplasmic retention of the transcriptional coactivator YAP. Tenascin-C also downregulates YAP pro-angiogenic target genes, thus reducing endothelial cell survival, proliferation, and tubulogenesis. Glioblastoma cells exposed to tenascin-C secrete pro-angiogenic factors that promote endothelial cell survival and tubulogenesis. Proteomic analysis of their secretome reveals a signature, including ephrin-B2, that predicts decreased survival of glioma patients. We find that ephrin-B2 is an important pro-angiogenic tenascin-C effector. Thus, we demonstrate dual activities for tenascin-C in glioblastoma angiogenesis and uncover potential targeting and prediction opportunities.
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Affiliation(s)
- Tristan Rupp
- The Microenvironmental Niche in Tumorigenesis and Targeted Therapy, INSERM U1109 - MN3T, 3 Avenue Molière, 67200 Strasbourg, France; Université de Strasbourg, 67000 Strasbourg, France; LabEx Medalis, Université de Strasbourg, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), 67000 Strasbourg, France
| | - Benoit Langlois
- The Microenvironmental Niche in Tumorigenesis and Targeted Therapy, INSERM U1109 - MN3T, 3 Avenue Molière, 67200 Strasbourg, France; Université de Strasbourg, 67000 Strasbourg, France; Institute of Molecular Medicine and Cell Research, University of Freiburg, 79104 Freiburg, Germany; Fédération de Médecine Translationnelle de Strasbourg (FMTS), 67000 Strasbourg, France
| | - Maria M Koczorowska
- Institute of Molecular Medicine and Cell Research, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | - Agata Radwanska
- iBV, INSERM, CNRS, Université Côte d'Azur, 06108 Nice, France
| | - Zhen Sun
- The Microenvironmental Niche in Tumorigenesis and Targeted Therapy, INSERM U1109 - MN3T, 3 Avenue Molière, 67200 Strasbourg, France; Université de Strasbourg, 67000 Strasbourg, France; LabEx Medalis, Université de Strasbourg, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), 67000 Strasbourg, France
| | - Thomas Hussenet
- The Microenvironmental Niche in Tumorigenesis and Targeted Therapy, INSERM U1109 - MN3T, 3 Avenue Molière, 67200 Strasbourg, France; Université de Strasbourg, 67000 Strasbourg, France; LabEx Medalis, Université de Strasbourg, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), 67000 Strasbourg, France
| | - Olivier Lefebvre
- The Microenvironmental Niche in Tumorigenesis and Targeted Therapy, INSERM U1109 - MN3T, 3 Avenue Molière, 67200 Strasbourg, France; Université de Strasbourg, 67000 Strasbourg, France; LabEx Medalis, Université de Strasbourg, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), 67000 Strasbourg, France
| | - Devadarssen Murdamoothoo
- The Microenvironmental Niche in Tumorigenesis and Targeted Therapy, INSERM U1109 - MN3T, 3 Avenue Molière, 67200 Strasbourg, France; Université de Strasbourg, 67000 Strasbourg, France; LabEx Medalis, Université de Strasbourg, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), 67000 Strasbourg, France
| | - Christiane Arnold
- The Microenvironmental Niche in Tumorigenesis and Targeted Therapy, INSERM U1109 - MN3T, 3 Avenue Molière, 67200 Strasbourg, France; Université de Strasbourg, 67000 Strasbourg, France; LabEx Medalis, Université de Strasbourg, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), 67000 Strasbourg, France
| | - Annick Klein
- The Microenvironmental Niche in Tumorigenesis and Targeted Therapy, INSERM U1109 - MN3T, 3 Avenue Molière, 67200 Strasbourg, France; Université de Strasbourg, 67000 Strasbourg, France; LabEx Medalis, Université de Strasbourg, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), 67000 Strasbourg, France
| | - Martin L Biniossek
- Institute of Molecular Medicine and Cell Research, University of Freiburg, 79104 Freiburg, Germany
| | - Vincent Hyenne
- The Microenvironmental Niche in Tumorigenesis and Targeted Therapy, INSERM U1109 - MN3T, 3 Avenue Molière, 67200 Strasbourg, France; Université de Strasbourg, 67000 Strasbourg, France; LabEx Medalis, Université de Strasbourg, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), 67000 Strasbourg, France
| | - Elise Naudin
- The Microenvironmental Niche in Tumorigenesis and Targeted Therapy, INSERM U1109 - MN3T, 3 Avenue Molière, 67200 Strasbourg, France; Université de Strasbourg, 67000 Strasbourg, France; LabEx Medalis, Université de Strasbourg, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), 67000 Strasbourg, France
| | - Ines Velazquez-Quesada
- The Microenvironmental Niche in Tumorigenesis and Targeted Therapy, INSERM U1109 - MN3T, 3 Avenue Molière, 67200 Strasbourg, France; Université de Strasbourg, 67000 Strasbourg, France; LabEx Medalis, Université de Strasbourg, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), 67000 Strasbourg, France
| | - Oliver Schilling
- Institute of Molecular Medicine and Cell Research, University of Freiburg, 79104 Freiburg, Germany; BIOSS Centre for Biological Signalling Studies, University of Freiburg, 79104 Freiburg, Germany; German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), 69120 Heidelberg, Germany
| | | | - Gertraud Orend
- The Microenvironmental Niche in Tumorigenesis and Targeted Therapy, INSERM U1109 - MN3T, 3 Avenue Molière, 67200 Strasbourg, France; Université de Strasbourg, 67000 Strasbourg, France; LabEx Medalis, Université de Strasbourg, 67000 Strasbourg, France; Fédération de Médecine Translationnelle de Strasbourg (FMTS), 67000 Strasbourg, France.
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60
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14-3-3 Regulates Actin Filament Formation in the Deep-Branching Eukaryote Giardia lamblia. mSphere 2017; 2:mSphere00248-17. [PMID: 28932813 PMCID: PMC5597967 DOI: 10.1128/msphere.00248-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 08/21/2017] [Indexed: 01/30/2023] Open
Abstract
The phosphoserine/phosphothreonine-binding protein 14-3-3 is known to regulate actin; this function has been previously attributed to sequestration of phosphorylated cofilin. 14-3-3 was identified as an actin-associated protein in the deep-branching eukaryote Giardia lamblia; however, Giardia lacks cofilin and all other canonical actin-binding proteins (ABPs). Thus, the role of G. lamblia 14-3-3 (Gl-14-3-3) in actin regulation was unknown. Gl-14-3-3 depletion resulted in an overall disruption of actin organization characterized by ectopically distributed short actin filaments. Using phosphatase and kinase inhibitors, we demonstrated that actin phosphorylation correlated with destabilization of the actin network and increased complex formation with 14-3-3, while blocking actin phosphorylation stabilized actin filaments and attenuated complex formation. Giardia's sole Rho family GTPase, Gl-Rac, modulates Gl-14-3-3's association with actin, providing the first connection between Gl-Rac and the actin cytoskeleton in Giardia. Giardia actin (Gl-actin) contains two putative 14-3-3 binding motifs, one of which (S330) is conserved in mammalian actin. Mutation of these sites reduced, but did not completely disrupt, the association with 14-3-3. Native gels and overlay assays indicate that intermediate proteins are required to support complex formation between 14-3-3 and actin. Overall, our results support a role for 14-3-3 as a regulator of actin; however, the presence of multiple 14-3-3-actin complexes suggests a more complex regulatory relationship than might be expected for a minimalistic parasite. IMPORTANCEGiardia lacks canonical actin-binding proteins. Gl-14-3-3 was identified as an actin interactor, but the significance of this interaction was unknown. Loss of Gl-14-3-3 results in ectopic short actin filaments, indicating that Gl-14-3-3 is an important regulator of the actin cytoskeleton in Giardia. Drug studies indicate that Gl-14-3-3 complex formation is in part phospho-regulated. We demonstrate that complex formation is downstream of Giardia's sole Rho family GTPase, Gl-Rac. This result provides the first mechanistic connection between Gl-Rac and Gl-actin in Giardia. Native gels and overlay assays indicate intermediate proteins are required to support the interaction between Gl-14-3-3 and Gl-actin, suggesting that Gl-14-3-3 is regulating multiple Gl-actin complexes.
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61
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Lei W, Myers KR, Rui Y, Hladyshau S, Tsygankov D, Zheng JQ. Phosphoinositide-dependent enrichment of actin monomers in dendritic spines regulates synapse development and plasticity. J Cell Biol 2017; 216:2551-2564. [PMID: 28659327 PMCID: PMC5551708 DOI: 10.1083/jcb.201612042] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 04/03/2017] [Accepted: 05/18/2017] [Indexed: 12/17/2022] Open
Abstract
Dendritic spines are small postsynaptic compartments of excitatory synapses in the vertebrate brain that are modified during learning, aging, and neurological disorders. The formation and modification of dendritic spines depend on rapid assembly and dynamic remodeling of the actin cytoskeleton in this highly compartmentalized space, but the precise mechanisms remain to be fully elucidated. In this study, we report that spatiotemporal enrichment of actin monomers (G-actin) in dendritic spines regulates spine development and plasticity. We first show that dendritic spines contain a locally enriched pool of G-actin that can be regulated by synaptic activity. We further find that this G-actin pool functions in spine development and its modification during synaptic plasticity. Mechanistically, the relatively immobile G-actin pool in spines depends on the phosphoinositide PI(3,4,5)P3 and involves the actin monomer-binding protein profilin. Together, our results have revealed a novel mechanism by which dynamic enrichment of G-actin in spines regulates the actin remodeling underlying synapse development and plasticity.
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Affiliation(s)
- Wenliang Lei
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA
- Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA
| | - Kenneth R Myers
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA
- Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA
| | - Yanfang Rui
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA
- Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA
| | - Siarhei Hladyshau
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA
| | - Denis Tsygankov
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA
| | - James Q Zheng
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA
- Department of Neurology, Emory University School of Medicine, Atlanta, GA
- Center for Neurodegenerative Diseases, Emory University School of Medicine, Atlanta, GA
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62
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Totaro A, Castellan M, Battilana G, Zanconato F, Azzolin L, Giulitti S, Cordenonsi M, Piccolo S. YAP/TAZ link cell mechanics to Notch signalling to control epidermal stem cell fate. Nat Commun 2017; 8:15206. [PMID: 28513598 PMCID: PMC5442321 DOI: 10.1038/ncomms15206] [Citation(s) in RCA: 198] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Accepted: 03/08/2017] [Indexed: 12/11/2022] Open
Abstract
How the behaviour of somatic stem cells (SCs) is influenced by mechanical signals remains a black-box in cell biology. Here we show that YAP/TAZ regulation by cell shape and rigidity of the extracellular matrix (ECM) dictates a pivotal SC decision: to remain undifferentiated and grow, or to activate a terminal differentiation programme. Notably, mechano-activation of YAP/TAZ promotes epidermal stemness by inhibition of Notch signalling, a key factor for epidermal differentiation. Conversely, YAP/TAZ inhibition by low mechanical forces induces Notch signalling and loss of SC traits. As such, mechano-dependent regulation of YAP/TAZ reflects into mechano-dependent regulation of Notch signalling. Mechanistically, at least in part, this is mediated by YAP/TAZ binding to distant enhancers activating the expression of Delta-like ligands, serving as ‘in cis' inhibitors of Notch. Thus YAP/TAZ mechanotransduction integrates with cell–cell communication pathways for fine-grained orchestration of SC decisions. Notch signalling is a fundamental negative regulator of epidermal stemness. Here, the authors show that cell mechanics through YAP/TAZ activity prevent primary human keratinocytes from differentiating by inhibiting cell-autonomous Notch signals.
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Affiliation(s)
- Antonio Totaro
- Department of Molecular Medicine (DMM), University of Padua School of Medicine, viale Colombo 3, Padua 35126, Italy
| | - Martina Castellan
- Department of Molecular Medicine (DMM), University of Padua School of Medicine, viale Colombo 3, Padua 35126, Italy
| | - Giusy Battilana
- Department of Molecular Medicine (DMM), University of Padua School of Medicine, viale Colombo 3, Padua 35126, Italy
| | - Francesca Zanconato
- Department of Molecular Medicine (DMM), University of Padua School of Medicine, viale Colombo 3, Padua 35126, Italy
| | - Luca Azzolin
- Department of Molecular Medicine (DMM), University of Padua School of Medicine, viale Colombo 3, Padua 35126, Italy
| | - Stefano Giulitti
- Department of Molecular Medicine (DMM), University of Padua School of Medicine, viale Colombo 3, Padua 35126, Italy.,Department of Industrial Engineering (DII), University of Padua, via Marzolo 9, Padua 35131, Italy
| | - Michelangelo Cordenonsi
- Department of Molecular Medicine (DMM), University of Padua School of Medicine, viale Colombo 3, Padua 35126, Italy
| | - Stefano Piccolo
- Department of Molecular Medicine (DMM), University of Padua School of Medicine, viale Colombo 3, Padua 35126, Italy
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63
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Serebryannyy LA, Yemelyanov A, Gottardi CJ, de Lanerolle P. Nuclear α-catenin mediates the DNA damage response via β-catenin and nuclear actin. J Cell Sci 2017; 130:1717-1729. [PMID: 28348105 DOI: 10.1242/jcs.199893] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Accepted: 03/20/2017] [Indexed: 12/29/2022] Open
Abstract
α-Catenin is an F-actin-binding protein widely recognized for its role in cell-cell adhesion. However, a growing body of literature indicates that α-catenin is also a nuclear protein. In this study, we show that α-catenin is able to modulate the sensitivity of cells to DNA damage and toxicity. Furthermore, nuclear α-catenin is actively recruited to sites of DNA damage. This recruitment occurs in a β-catenin-dependent manner and requires nuclear actin polymerization. These findings provide mechanistic insight into the WNT-mediated regulation of the DNA damage response and suggest a novel role for the α-catenin-β-catenin complex in the nucleus.
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Affiliation(s)
- Leonid A Serebryannyy
- Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA
| | - Alex Yemelyanov
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Cara J Gottardi
- Department of Medicine, Feinberg School 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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64
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Knöll B, Beck H. The cytoskeleton and nucleus: the role of actin as a modulator of neuronal gene expression. ACTA ACUST UNITED AC 2017. [DOI: 10.1007/s13295-010-0013-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Abstract
Actin, arranged for example in stress fibres, provides a fundamental cytoskeletal framework function to all cell types. Notably, there is now mounting evidence that, in addition to cytoplasmic cytoskeletal regulation, actin treadmilling provides a signal modulating nuclear gene expression. In altering gene regulation, cytoplasmic and most likely also a nucleus-resident actin provides an additional (gene) regulatory twist to cell motility. So far, the transcription factor serum response factor (SRF) alongside its myocardin-related transcription factor (MRTF) cofactors has emerged as the main target of actin dynamics. In this review, we discuss the impact of actin signalling on nuclear gene expression in the nervous system, where the actin-MRTF-SRF module contributes to various processes including neuronal motility.
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Affiliation(s)
- B. Knöll
- Institute for Physiological Chemistry, University of Ulm Albert-Einstein-Allee 11, 89081 Ulm, Germany
| | - H. Beck
- Institute for Physiological Chemistry, University of Ulm Albert-Einstein-Allee 11, 89081 Ulm, Germany
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65
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Finch-Edmondson M, Sudol M. Framework to function: mechanosensitive regulators of gene transcription. Cell Mol Biol Lett 2016; 21:28. [PMID: 28536630 PMCID: PMC5415767 DOI: 10.1186/s11658-016-0028-7] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 11/16/2016] [Indexed: 01/06/2023] Open
Abstract
Mechanobiology has shifted our understanding of fundamental cellular and physiological functions. Changes to the stiffness of the extracellular matrix, cell rigidity, or shape of the cell environment were considered in the past to be a consequence of aging or pathological processes. We now understand that these factors can actually be causative biological mediators of cell growth to control organ size. Mechanical cues are known to trigger a relatively fast translocation of specific transcriptional co-factors such as MRTFs, YAP and TAZ from the cytoplasm to the cell nucleus to initiate discrete transcriptional programs. The focus of this review is the molecular mechanisms by which biophysical stimuli that induce changes in cytoplasmic actin dynamics are communicated within cells to elicit gene-specific transcription via nuclear localisation or activation of specialized transcription factors, namely MRTFs and the Hippo pathway effectors YAP and TAZ. We propose here that MRTFs, YAP and TAZ closely collaborate as mechano-effectors.
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Affiliation(s)
- Megan Finch-Edmondson
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, 117411 Singapore, Singapore.,Department of Physiology, National University of Singapore, Yong Loo Lin School of Medicine, 2 Medical Drive, 117597 Singapore, Singapore
| | - Marius Sudol
- Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, 117411 Singapore, Singapore.,Department of Physiology, National University of Singapore, Yong Loo Lin School of Medicine, 2 Medical Drive, 117597 Singapore, Singapore
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66
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Actin Is Crucial for All Kinetically Distinguishable Forms of Endocytosis at Synapses. Neuron 2016; 92:1020-1035. [PMID: 27840001 DOI: 10.1016/j.neuron.2016.10.014] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 06/16/2016] [Accepted: 10/04/2016] [Indexed: 01/18/2023]
Abstract
Mechanical force is needed to mediate endocytosis. Whether actin, the most abundant force-generating molecule, is essential for endocytosis is highly controversial in mammalian cells, particularly synapses, likely due to the use of actin blockers, the efficiency and specificity of which are often unclear in the studied cell. Here we addressed this issue using a knockout approach combined with measurements of membrane capacitance and fission pore conductance, imaging of vesicular protein endocytosis, and electron microscopy. We found that two actin isoforms, β- and γ-actin, are crucial for slow, rapid, bulk, and overshoot endocytosis at large calyx-type synapses, and for slow endocytosis and bulk endocytosis at small hippocampal synapses. Polymerized actin provides mechanical force to form endocytic pits. Actin also facilitates replenishment of the readily releasable vesicle pool, likely via endocytic clearance of active zones. We conclude that polymerized actin provides mechanical force essential for all kinetically distinguishable forms of endocytosis at synapses.
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67
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Muehlich S, Rehm M, Ebenau A, Goppelt-Struebe M. Synergistic induction of CTGF by cytochalasin D and TGFβ-1 in primary human renal epithelial cells: Role of transcriptional regulators MKL1, YAP/TAZ and Smad2/3. Cell Signal 2016; 29:31-40. [PMID: 27721022 DOI: 10.1016/j.cellsig.2016.10.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Revised: 09/26/2016] [Accepted: 10/06/2016] [Indexed: 02/08/2023]
Abstract
Changes in cell morphology that involve alterations of the actin cytoskeleton are a hallmark of diseased renal tubular epithelial cells. While the impact of actin remodeling on gene expression has been analyzed in many model systems based on cell lines, this study investigated human primary tubular epithelial cells isolated from healthy parts of tumor nephrectomies. Latrunculin B (LatB) and cytochalasin D (CytoD) were used to modulate G-actin levels in a receptor-independent manner. Both compounds (at 0.5μM) profoundly altered F-actin structures in a Rho kinase-dependent manner, but only CytoD strongly induced the pro-fibrotic factor CTGF (connective tissue growth factor). CTGF induction was dependent on YAP as shown by transient downregulation experiments. However, CytoD did not alter the nuclear localization of either YAP or TAZ, whereas LatB reduced nuclear levels particularly of TAZ. CytoD modified MKL1, a coactivator of serum response factor (SRF) regulating CTGF induction, and promoted its nuclear localization. TGFβ-1 is one of the major factors involved in tubulointerstitial disease and an inducer of CTGF. Preincubation with CytoD but not LatB synergistically enhanced the TGFβ-1-stimulated synthesis of CTGF, both in cells cultured on plastic dishes as well as in polarized epithelial cells. CytoD had no direct effect on the phosphorylation of Smad2/3, but facilitated their phosphorylation and thus activation by TGFβ-1. Our present findings provide evidence that morphological alterations have a strong impact on cellular signaling of one of the major pro-fibrotic factors, TGFβ-1. However, our data also indicate that changes in cell morphology per se cannot predict those interactions which are critically dependent on molecular fine tuning of actin reorganization.
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Affiliation(s)
- Susanne Muehlich
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-University Munich, Goethestrasse 33, D-80336 München, Germany
| | - Margot Rehm
- Department of Nephrology and Hypertension, Friedrich-Alexander-Universität Erlangen-Nürnberg, Loschgestrasse 8, D-91054 Erlangen, Germany
| | - Astrid Ebenau
- Department of Nephrology and Hypertension, Friedrich-Alexander-Universität Erlangen-Nürnberg, Loschgestrasse 8, D-91054 Erlangen, Germany
| | - Margarete Goppelt-Struebe
- Department of Nephrology and Hypertension, Friedrich-Alexander-Universität Erlangen-Nürnberg, Loschgestrasse 8, D-91054 Erlangen, Germany.
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68
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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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69
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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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70
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Abstract
Actin polymerizes and forms filamentous structures (F-actin) in the cytoplasm of eukaryotic cells. It also exists in the nucleus and regulates various nucleic acid transactions, particularly through its incorporation into multiple chromatin-remodeling complexes. However, the specific structure of actin and the mechanisms that regulate its polymeric nature inside the nucleus remain unknown. Here, we report the crystal structure of nuclear actin (N-actin) complexed with actin-related protein 4 (Arp4) and the helicase-SANT-associated (HSA) domain of the chromatin remodeler Swr1. The inner face and barbed end of N-actin are sequestered by interactions with Arp4 and the HSA domain, respectively, which prevents N-actin from polymerization and binding to many actin regulators. The two major domains of N-actin are more twisted than those of globular actin (G-actin), and its nucleotide-binding pocket is occluded, freeing N-actin from binding to and regulation by ATP. These findings revealed the salient structural features of N-actin that distinguish it from its cytoplasmic counterpart and provide a rational basis for its functions and regulation inside the nucleus.
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71
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Sen B, Xie Z, Uzer G, Thompson WR, Styner M, Wu X, Rubin J. Intranuclear Actin Regulates Osteogenesis. Stem Cells 2016; 33:3065-76. [PMID: 26140478 DOI: 10.1002/stem.2090] [Citation(s) in RCA: 89] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2015] [Revised: 06/02/2015] [Accepted: 06/06/2015] [Indexed: 12/22/2022]
Abstract
Depolymerization of the actin cytoskeleton induces nuclear trafficking of regulatory proteins and global effects on gene transcription. We here show that in mesenchymal stem cells (MSCs), cytochalasin D treatment causes rapid cofilin-/importin-9-dependent transfer of G-actin into the nucleus. The continued presence of intranuclear actin, which forms rod-like structures that stain with phalloidin, is associated with induction of robust expression of the osteogenic genes osterix and osteocalcin in a Runx2-dependent manner, and leads to acquisition of osteogenic phenotype. Adipogenic differentiation also occurs, but to a lesser degree. Intranuclear actin leads to nuclear export of Yes-associated protein (YAP); maintenance of nuclear YAP inhibits Runx2 initiation of osteogenesis. Injection of cytochalasin into the tibial marrow space of live mice results in abundant bone formation within the space of 1 week. In sum, increased intranuclear actin forces MSC into osteogenic lineage through controlling Runx2 activity; this process may be useful for clinical objectives of forming bone.
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Affiliation(s)
- Buer Sen
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Zhihui Xie
- 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
| | - William R Thompson
- Department of Physical Therapy, University of Indiana-Purdue, Indianapolis, Indiana
| | - Maya Styner
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Xin Wu
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Janet Rubin
- Department of Medicine, University of North Carolina, Chapel Hill, North Carolina, USA
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Cahill ME, Bagot RC, Gancarz AM, Walker DM, Sun H, Wang ZJ, Heller EA, Feng J, Kennedy PJ, Koo JW, Cates HM, Neve RL, Shen L, Dietz DM, Nestler EJ. Bidirectional Synaptic Structural Plasticity after Chronic Cocaine Administration Occurs through Rap1 Small GTPase Signaling. Neuron 2016; 89:566-82. [PMID: 26844834 DOI: 10.1016/j.neuron.2016.01.031] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Revised: 01/11/2016] [Accepted: 01/19/2016] [Indexed: 12/25/2022]
Abstract
Dendritic spines are the sites of most excitatory synapses in the CNS, and opposing alterations in the synaptic structure of medium spiny neurons (MSNs) of the nucleus accumbens (NAc), a primary brain reward region, are seen at early versus late time points after cocaine administration. Here we investigate the time-dependent molecular and biochemical processes that regulate this bidirectional synaptic structural plasticity of NAc MSNs and associated changes in cocaine reward in response to chronic cocaine exposure. Our findings reveal key roles for the bidirectional synaptic expression of the Rap1b small GTPase and an associated local synaptic protein translation network in this process. The transcriptional mechanisms and pathway-specific inputs to NAc that regulate Rap1b expression are also characterized. Collectively, these findings provide a precise mechanism by which nuclear to synaptic interactions induce "metaplasticity" in NAc MSNs, and we reveal the specific effects of this plasticity on reward behavior in a brain circuit-specific manner.
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Affiliation(s)
- Michael E Cahill
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Rosemary C Bagot
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Amy M Gancarz
- Department of Pharmacology and Toxicology, Research Institute on Addictions, Program in Neuroscience, State University of New York at Buffalo, Buffalo, NY 14214, USA
| | - Deena M Walker
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - HaoSheng Sun
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Zi-Jun Wang
- Department of Pharmacology and Toxicology, Research Institute on Addictions, Program in Neuroscience, State University of New York at Buffalo, Buffalo, NY 14214, USA
| | - Elizabeth A Heller
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Jian Feng
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Pamela J Kennedy
- Department of Psychology, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Ja Wook Koo
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Hannah M Cates
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Rachael L Neve
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Li Shen
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - David M Dietz
- Department of Pharmacology and Toxicology, Research Institute on Addictions, Program in Neuroscience, State University of New York at Buffalo, Buffalo, NY 14214, USA
| | - Eric J Nestler
- Fishberg Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA.
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73
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A Role for Nuclear Actin in HDAC 1 and 2 Regulation. Sci Rep 2016; 6:28460. [PMID: 27345839 PMCID: PMC4921920 DOI: 10.1038/srep28460] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 05/26/2016] [Indexed: 01/13/2023] Open
Abstract
Class I histone deacetylases (HDACs) are known to remove acetyl groups from histone tails. This liberates positive charges on the histone tail and allows for tighter winding of DNA, preventing transcription factor binding and gene activation. Although the functions of HDAC proteins are becoming apparent both biochemically and clinically, how this class of proteins is regulated remains poorly understood. We identified a novel interaction between nuclear actin and HDAC 1 and HDAC 2. Nuclear actin has been previously shown to interact with a growing list of nuclear proteins including chromatin remodeling complexes, transcription factors and RNA polymerases. We find that monomeric actin is able to bind the class I HDAC complex. Furthermore, increasing the concentration of actin in HeLa nuclear extracts was able to suppress overall HDAC function. Conversely, polymerizing nuclear actin increased HDAC activity and decreased histone acetylation. Moreover, the interaction between class I HDACs and nuclear actin was found to be activity dependent. Together, our data suggest nuclear actin is able to regulate HDAC 1 and 2 activity.
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74
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Myocardin-Related Transcription Factor A Activation by Competition with WH2 Domain Proteins for Actin Binding. Mol Cell Biol 2016; 36:1526-39. [PMID: 26976641 DOI: 10.1128/mcb.01097-15] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 03/03/2016] [Indexed: 01/14/2023] Open
Abstract
The myocardin-related transcription factors (MRTFs) are coactivators of serum response factor (SRF)-mediated gene expression. Activation of MRTF-A occurs in response to alterations in actin dynamics and critically requires the dissociation of repressive G-actin-MRTF-A complexes. However, the mechanism leading to the release of MRTF-A remains unclear. Here we show that WH2 domains compete directly with MRTF-A for actin binding. Actin nucleation-promoting factors, such as N-WASP and WAVE2, as well as isolated WH2 domains, including those of Spire2 and Cobl, activate MRTF-A independently of changes in actin dynamics. Simultaneous inhibition of Arp2-Arp3 or mutation of the CA region only partially reduces MRTF-A activation by N-WASP and WAVE2. Recombinant WH2 domains and the RPEL domain of MRTF-A bind mutually exclusively to cellular and purified G-actin in vitro The competition by different WH2 domains correlates with MRTF-SRF activation. Following serum stimulation, nonpolymerizable actin dissociates from MRTF-A, and de novo formation of the G-actin-RPEL complex is impaired by a transferable factor. Our work demonstrates that WH2 domains activate MRTF-A and contribute to target gene regulation by a competitive mechanism, independently of their role in actin filament formation.
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75
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Almuzzaini B, Sarshad AA, Rahmanto AS, Hansson ML, Von Euler A, Sangfelt O, Visa N, Farrants AKÖ, Percipalle P. In β-actin knockouts, epigenetic reprogramming and rDNA transcription inactivation lead to growth and proliferation defects. FASEB J 2016; 30:2860-73. [PMID: 27127100 DOI: 10.1096/fj.201600280r] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 04/18/2016] [Indexed: 12/18/2022]
Abstract
Actin and nuclear myosin 1 (NM1) are regulators of transcription and chromatin organization. Using a genome-wide approach, we report here that β-actin binds intergenic and genic regions across the mammalian genome, associated with both protein-coding and rRNA genes. Within the rDNA, the distribution of β-actin correlated with NM1 and the other subunits of the B-WICH complex, WSTF and SNF2h. In β-actin(-/-) mouse embryonic fibroblasts (MEFs), we found that rRNA synthesis levels decreased concomitantly with drops in RNA polymerase I (Pol I) and NM1 occupancies across the rRNA gene. Reintroduction of wild-type β-actin, in contrast to mutated forms with polymerization defects, efficiently rescued rRNA synthesis underscoring the direct role for a polymerization-competent form of β-actin in Pol I transcription. The rRNA synthesis defects in the β-actin(-/-) MEFs are a consequence of epigenetic reprogramming with up-regulation of the repressive mark H3K4me1 (monomethylation of lys4 on histone H3) and enhanced chromatin compaction at promoter-proximal enhancer (T0 sequence), which disturb binding of the transcription factor TTF1. We propose a novel genome-wide mechanism where the polymerase-associated β-actin synergizes with NM1 to coordinate permissive chromatin with Pol I transcription, cell growth, and proliferation.-Almuzzaini, B., Sarshad, A. A. , Rahmanto, A. S., Hansson, M. L., Von Euler, A., Sangfelt, O., Visa, N., Farrants, A.-K. Ö., Percipalle, P. In β-actin knockouts, epigenetic reprogramming and rDNA transcription inactivation lead to growth and proliferation defects.
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Affiliation(s)
- Bader Almuzzaini
- Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden; Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden; and
| | - Aishe A Sarshad
- Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden
| | - Aldwin S Rahmanto
- Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden
| | - Magnus L Hansson
- Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden
| | - Anne Von Euler
- King Abdullah International Medical Research Center, National Guard Health Affairs, Riyadh, Saudi Arabia
| | - Olle Sangfelt
- Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden
| | - Neus Visa
- King Abdullah International Medical Research Center, National Guard Health Affairs, Riyadh, Saudi Arabia
| | | | - Piergiorgio Percipalle
- Department of Cell and Molecular Biology, Karolinska Institute, Stockholm, Sweden; King Abdullah International Medical Research Center, National Guard Health Affairs, Riyadh, Saudi Arabia Division of Science, Department of Biology, New York University Abu Dhabi, Abu Dhabi, United Arab Emirates
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76
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Nuclear F-actin enhances the transcriptional activity of β-catenin by increasing its nuclear localization and binding to chromatin. Histochem Cell Biol 2016; 145:389-99. [DOI: 10.1007/s00418-016-1416-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2016] [Indexed: 01/15/2023]
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77
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Rangrez AY, Eden M, Poyanmehr R, Kuhn C, Stiebeling K, Dierck F, Bernt A, Lüllmann-Rauch R, Weiler H, Kirchof P, Frank D, Frey N. Myozap Deficiency Promotes Adverse Cardiac Remodeling via Differential Regulation of Mitogen-activated Protein Kinase/Serum-response Factor and β-Catenin/GSK-3β Protein Signaling. J Biol Chem 2015; 291:4128-43. [PMID: 26719331 DOI: 10.1074/jbc.m115.689620] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Indexed: 01/22/2023] Open
Abstract
The intercalated disc (ID) is a "hot spot" for heart disease, as several ID proteins have been found mutated in cardiomyopathy. Myozap is a recent addition to the list of ID proteins and has been implicated in serum-response factor signaling. To elucidate the cardiac consequences of targeted deletion of myozap in vivo, we generated myozap-null mutant (Mzp(-/-)) mice. Although Mzp(-/-) mice did not exhibit a baseline phenotype, increased biomechanical stress due to pressure overload led to accelerated cardiac hypertrophy, accompanied by "super"-induction of fetal genes, including natriuretic peptides A and B (Nppa/Nppb). Moreover, Mzp(-/-) mice manifested a severe reduction of contractile function, signs of heart failure, and increased mortality. Expression of other ID proteins like N-cadherin, desmoplakin, connexin-43, and ZO-1 was significantly perturbed upon pressure overload, underscored by disorganization of the IDs in Mzp(-/-) mice. Exploration of the molecular causes of enhanced cardiac hypertrophy revealed significant activation of β-catenin/GSK-3β signaling, whereas MAPK and MKL1/serum-response factor pathways were inhibited. In summary, myozap is required for proper adaptation to increased biomechanical stress. In broader terms, our data imply an essential function of the ID in cardiac remodeling beyond a mere structural role and emphasize the need for a better understanding of this molecular structure in the context of heart disease.
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Affiliation(s)
- Ashraf Yusuf Rangrez
- From the Department of Internal Medicine III, Molecular Cardiology and Angiology, and
| | - Matthias Eden
- From the Department of Internal Medicine III, Molecular Cardiology and Angiology, and
| | - Reza Poyanmehr
- From the Department of Internal Medicine III, Molecular Cardiology and Angiology, and
| | - Christian Kuhn
- From the Department of Internal Medicine III, Molecular Cardiology and Angiology, and
| | - Katharina Stiebeling
- From the Department of Internal Medicine III, Molecular Cardiology and Angiology, and
| | - Franziska Dierck
- From the Department of Internal Medicine III, Molecular Cardiology and Angiology, and
| | - Alexander Bernt
- From the Department of Internal Medicine III, Molecular Cardiology and Angiology, and
| | - Renate Lüllmann-Rauch
- German Centre for Cardiovascular Research (DZHK, partner site Hamburg/Kiel/Lübeck), University Medical Center Schleswig-Holstein, Kiel D-24105, Germany
| | - Hartmut Weiler
- the Anatomical Institute, Christian Albrechts University of Kiel, Kiel D-24098, Germany
| | - Paulus Kirchof
- the Blood Research Institute, Blood Center of Wisconsin, Milwaukee, Wisconsin 53233, and
| | - Derk Frank
- From the Department of Internal Medicine III, Molecular Cardiology and Angiology, and
| | - Norbert Frey
- From the Department of Internal Medicine III, Molecular Cardiology and Angiology, and
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78
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Calvo F, Ranftl R, Hooper S, Farrugia AJ, Moeendarbary E, Bruckbauer A, Batista F, Charras G, Sahai E. Cdc42EP3/BORG2 and Septin Network Enables Mechano-transduction and the Emergence of Cancer-Associated Fibroblasts. Cell Rep 2015; 13:2699-714. [PMID: 26711338 PMCID: PMC4700053 DOI: 10.1016/j.celrep.2015.11.052] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 09/11/2015] [Accepted: 11/16/2015] [Indexed: 11/19/2022] Open
Abstract
Cancer-associated fibroblasts (CAFs) are non-cancerous cells found in solid tumors that remodel the tumor matrix and promote cancer invasion and angiogenesis. Here, we demonstrate that Cdc42EP3/BORG2 is required for the matrix remodeling, invasion, angiogenesis, and tumor-growth-promoting abilities of CAFs. Cdc42EP3 functions by coordinating the actin and septin networks. Furthermore, depletion of SEPT2 has similar effects to those of loss of Cdc42EP3, indicating a role for the septin network in the tumor stroma. Cdc42EP3 is upregulated early in fibroblast activation and precedes the emergence of the highly contractile phenotype characteristic of CAFs. Depletion of Cdc42EP3 in normal fibroblasts prevents their activation by cancer cells. We propose that Cdc42EP3 sensitizes fibroblasts to further cues-in particular, those activating actomyosin contractility-and thereby enables the generation of the pathological activated fibroblast state.
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Affiliation(s)
- Fernando Calvo
- Tumour Cell Biology Laboratory, Francis Crick Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK; Tumour Microenvironment Team, Division of Cancer Biology, Institute of Cancer Research, 237 Fulham Road, London SW2 6JB, UK.
| | - Romana Ranftl
- Tumour Microenvironment Team, Division of Cancer Biology, Institute of Cancer Research, 237 Fulham Road, London SW2 6JB, UK
| | - Steven Hooper
- Tumour Cell Biology Laboratory, Francis Crick Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
| | - Aaron J Farrugia
- Tumour Microenvironment Team, Division of Cancer Biology, Institute of Cancer Research, 237 Fulham Road, London SW2 6JB, UK
| | - Emad Moeendarbary
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK; Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02142, USA
| | - Andreas Bruckbauer
- Lymphocyte Interaction Laboratory, Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
| | - Facundo Batista
- Lymphocyte Interaction Laboratory, Cancer Research UK London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
| | - Guillaume Charras
- London Centre for Nanotechnology, University College London, London WC1H 0AH, UK; Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
| | - Erik Sahai
- Tumour Cell Biology Laboratory, Francis Crick Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK.
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79
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Migocka-Patrzałek M, Makowiecka A, Nowak D, Mazur AJ, Hofmann WA, Malicka-Błaszkiewicz M. β- and γ-Actins in the nucleus of human melanoma A375 cells. Histochem Cell Biol 2015; 144:417-28. [PMID: 26239425 PMCID: PMC4628621 DOI: 10.1007/s00418-015-1349-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2015] [Indexed: 11/13/2022]
Abstract
Actin is a highly conserved protein that is expressed in all eukaryotic cells and has essential functions in the cytoplasm and the nucleus. Nuclear actin is involved in transcription by all three RNA polymerases, chromatin remodelling, RNA processing, intranuclear transport, nuclear export and in maintenance of the nuclear architecture. The nuclear actin level and polymerization state are important factors regulating nuclear processes such as transcription. Our study shows that, in contrast to the cytoplasm, the majority of endogenous nuclear actin is unpolymerized in human melanoma A375 cells. Most mammalian cells express the two non-muscle β- and γ-actin isoforms that differ in only four amino acids. Despite their sequence similarity, studies analysing the cytoplasmic functions of these isoforms demonstrated that β- and γ-actins show differences in localization and function. However, little is known about the involvement of the individual actin isoforms in nuclear processes. Here, we used the human melanoma A375 cell line to analyse actin isoforms in regard to their nuclear localization. We show that both β- and γ-non-muscle actin isoforms are present in nuclei of these cells. Immunolocalization studies demonstrate that both isoforms co-localize with RNA polymerase II and hnRNP U. However, we observe differences in the ratio of cytoplasmic to nuclear actin distribution between the isoforms. We show that β-actin has a significantly higher nucleus-to-cytoplasm ratio than γ-actin.
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Affiliation(s)
- Marta Migocka-Patrzałek
- Department of Animal Developmental Biology, Institute of Experimental Biology, Faculty of Biological Sciences, University of Wroclaw, Sienkiewicza 21, 50-335, Wroclaw, Poland.
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland.
- Department of Physiology and Biophysics, University at Buffalo State University of New York, Buffalo, NY, USA.
| | - Aleksandra Makowiecka
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | - Dorota Nowak
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | - Antonina J Mazur
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Wroclaw, Poland
| | - Wilma A Hofmann
- Department of Physiology and Biophysics, University at Buffalo State University of New York, Buffalo, NY, USA
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80
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Rotty JD, Bear JE. Competition and collaboration between different actin assembly pathways allows for homeostatic control of the actin cytoskeleton. BIOARCHITECTURE 2015; 5:27-34. [PMID: 26430713 DOI: 10.1080/19490992.2015.1090670] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Tremendous insight into actin-associated proteins has come from careful biochemical and cell biological characterization of their activities and regulation. However, many studies of their cellular behavior have only considered each in isolation. Recent efforts reveal that assembly factors compete for polymerization-competent actin monomers, suggesting that actin is homeostatically regulated. It seems that a major regulatory component is competition between Arp2/3-activating nucleation promoting factors and profilin for actin monomers. The result is differential delivery of actin to different pathways, allowing for simultaneous assembly of competing F-actin structures and collaborative building of higher order cellular structures. Although there are likely to be additional factors that regulate actin homeostasis, especially in a cell type-dependent fashion, we advance the notion that competition between actin assembly factors results in a tunable system that can be adjusted according to extracellular and intracellular cues.
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Affiliation(s)
- Jeremy D Rotty
- a UNC Lineberger Comprehensive Cancer Center; University of North Carolina at Chapel Hill ; Chapel Hill , NC USA.,b Department of Cell Biology and Physiology; University of North Carolina at Chapel Hill ; Chapel Hill , NC USA
| | - James E Bear
- a UNC Lineberger Comprehensive Cancer Center; University of North Carolina at Chapel Hill ; Chapel Hill , NC USA.,b Department of Cell Biology and Physiology; University of North Carolina at Chapel Hill ; Chapel Hill , NC USA
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81
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Nuclear actin and myosins in adenovirus infection. Exp Cell Res 2015; 338:170-82. [PMID: 26226218 DOI: 10.1016/j.yexcr.2015.07.025] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 07/24/2015] [Accepted: 07/25/2015] [Indexed: 11/21/2022]
Abstract
Adenovirus serotypes have been shown to cause drastic changes in nuclear organization, including the transcription machinery, during infection. This ability of adenovirus to subvert transcription in the host cell facilitates viral replication. Because nuclear actin and nuclear myosin I, myosin V and myosin VI have been implicated as direct regulators of transcription and important factors in the replication of other viruses, we sought to determine how nuclear actin and myosins are involved in adenovirus infection. We first confirmed reorganization of the host's transcription machinery to viral replication centers. We found that nuclear actin also reorganizes to sites of transcription through the intermediate but not the advanced late phase of viral infection. Furthermore, nuclear myosin I localized with nuclear actin and sites of transcription in viral replication centers. Intriguingly, nuclear myosins V and VI, which also reorganized to viral replication centers, exhibited different localization patterns, suggesting specialized roles for these nuclear myosins. Finally, we assessed the role of actin in adenovirus infection and found both cytoplasmic and nuclear actin likely play roles in adenovirus infection and replication. Together our data suggest the involvement of actin and multiple myosins in the nuclear replication and late viral gene expression of adenovirus.
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82
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A novel inhibitory mechanism of MRTF-A/B on the ICAM-1 gene expression in vascular endothelial cells. Sci Rep 2015; 5:10627. [PMID: 26024305 PMCID: PMC4448521 DOI: 10.1038/srep10627] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Accepted: 04/22/2015] [Indexed: 01/09/2023] Open
Abstract
The roles of myocardin-related transcription factor A (MRTF-A) and MRTF-B in vascular endothelial cells are not completely understood. Here, we found a novel regulatory mechanism for MRTF-A/B function. MRTF-A/B tend to accumulate in the nucleus in arterial endothelial cells in vivo and human aortic endothelial cells (HAoECs) in vitro. In HAoECs, nuclear localization of MRTF-A/B was not significantly affected by Y27632 or latrunculin B, primarily due to the reduced binding of MRTF-A/B to G-actin and in part, to the low level of MRTF-A phosphorylation by ERK. MRTF-A/B downregulation by serum depletion or transfection of siRNA against MRTF-A and/or MRTF-B induced ICAM-1 expression in HAoECs. It is known that nuclear import of nuclear factor−κB (NF−κB) plays a key role in ICAM-1 gene transcription. However, nuclear accumulation of NF−κB p65 was not observed in MRTF-A/B-depleted HAoECs. Our present findings suggest that MRTF-A/B inhibit ICAM-1 mRNA expression by forming a complex with NF−κB p65 in the nucleus. Conversely, downregulation of MRTF-A/B alleviates this negative regulation without further translocation of NF−κB p65 into the nucleus. These results reveal the novel roles of MRTF-A/B in the homeostasis of vascular endothelium.
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83
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Drummond MC, Barzik M, Bird JE, Zhang DS, Lechene CP, Corey DP, Cunningham LL, Friedman TB. Live-cell imaging of actin dynamics reveals mechanisms of stereocilia length regulation in the inner ear. Nat Commun 2015; 6:6873. [PMID: 25898120 PMCID: PMC4411292 DOI: 10.1038/ncomms7873] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Accepted: 03/06/2015] [Indexed: 02/05/2023] Open
Abstract
The maintenance of sensory hair cell stereocilia is critical for lifelong hearing; however, mechanisms of structural homeostasis remain poorly understood. Conflicting models propose that stereocilia F-actin cores are either continually renewed every 24-48 h via a treadmill or are stable, exceptionally long-lived structures. Here to distinguish between these models, we perform an unbiased survey of stereocilia actin dynamics in more than 500 utricle hair cells. Live-imaging EGFP-β-actin or dendra2-β-actin reveal stable F-actin cores with turnover and elongation restricted to stereocilia tips. Fixed-cell microscopy of wild-type and mutant β-actin demonstrates that incorporation of actin monomers into filaments is required for localization to stereocilia tips. Multi-isotope imaging mass spectrometry and live imaging of single differentiating hair cells capture stereociliogenesis and explain uniform incorporation of (15)N-labelled protein and EGFP-β-actin into nascent stereocilia. Collectively, our analyses support a model in which stereocilia actin cores are stable structures that incorporate new F-actin only at the distal tips.
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Affiliation(s)
- Meghan C Drummond
- Laboratory of Molecular Genetics, Section on Human Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Melanie Barzik
- Laboratory of Molecular Genetics, Section on Human Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Jonathan E Bird
- Laboratory of Molecular Genetics, Section on Human Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Duan-Sun Zhang
- Department of Neurobiology, Harvard Medical School and Howard Hughes Medical Institute, Boston, Massachusetts 02115, USA
| | - Claude P Lechene
- 1] National Resource for Imaging Mass Spectrometry, Brigham and Women's Hospital and Harvard Medical School, Cambridge, Massachusetts 02139, USA [2] Division of Genetics, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Cambridge, Massachusetts 02139, USA
| | - David P Corey
- Department of Neurobiology, Harvard Medical School and Howard Hughes Medical Institute, Boston, Massachusetts 02115, USA
| | - Lisa L Cunningham
- Section on Sensory Cell Biology, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Thomas B Friedman
- Laboratory of Molecular Genetics, Section on Human Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland 20892, USA
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84
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Kalo A, Kanter I, Shraga A, Sheinberger J, Tzemach H, Kinor N, Singer RH, Lionnet T, Shav-Tal Y. Cellular Levels of Signaling Factors Are Sensed by β-actin Alleles to Modulate Transcriptional Pulse Intensity. Cell Rep 2015; 11:419-32. [PMID: 25865891 DOI: 10.1016/j.celrep.2015.03.039] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Revised: 02/18/2015] [Accepted: 03/16/2015] [Indexed: 01/11/2023] Open
Abstract
The transcriptional response of β-actin to extra-cellular stimuli is a paradigm for transcription factor complex assembly and regulation. Serum induction leads to a precisely timed pulse of β-actin transcription in the cell population. Actin protein is proposed to be involved in this response, but it is not known whether cellular actin levels affect nuclear β-actin transcription. We perturbed the levels of key signaling factors and examined the effect on the induced transcriptional pulse by following endogenous β-actin alleles in single living cells. Lowering serum response factor (SRF) protein levels leads to loss of pulse integrity, whereas reducing actin protein levels reveals positive feedback regulation, resulting in elevated gene activation and a prolonged transcriptional response. Thus, transcriptional pulse fidelity requires regulated amounts of signaling proteins, and perturbations in factor levels eliminate the physiological response, resulting in either tuning down or exaggeration of the transcriptional pulse.
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Affiliation(s)
- Alon Kalo
- The Mina and Everard Goodman Faculty of Life Sciences and Institute of Nanotechnology, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Itamar Kanter
- The Mina and Everard Goodman Faculty of Life Sciences and Institute of Nanotechnology, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Amit Shraga
- The Mina and Everard Goodman Faculty of Life Sciences and Institute of Nanotechnology, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Jonathan Sheinberger
- The Mina and Everard Goodman Faculty of Life Sciences and Institute of Nanotechnology, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Hadar Tzemach
- The Mina and Everard Goodman Faculty of Life Sciences and Institute of Nanotechnology, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Noa Kinor
- The Mina and Everard Goodman Faculty of Life Sciences and Institute of Nanotechnology, Bar-Ilan University, Ramat Gan 5290002, Israel
| | - Robert H Singer
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA; Transcription Imaging Consortium, Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA 20147, USA; Gruss Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Timothée Lionnet
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, NY 10461, USA; Transcription Imaging Consortium, Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA 20147, USA
| | - Yaron Shav-Tal
- The Mina and Everard Goodman Faculty of Life Sciences and Institute of Nanotechnology, Bar-Ilan University, Ramat Gan 5290002, Israel.
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85
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Giehl K, Keller C, Muehlich S, Goppelt-Struebe M. Actin-mediated gene expression depends on RhoA and Rac1 signaling in proximal tubular epithelial cells. PLoS One 2015; 10:e0121589. [PMID: 25816094 PMCID: PMC4376694 DOI: 10.1371/journal.pone.0121589] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2014] [Accepted: 02/14/2015] [Indexed: 12/29/2022] Open
Abstract
Morphological alterations of cells can lead to modulation of gene expression. An essential link is the MKL1-dependent activation of serum response factor (SRF), which translates changes in the ratio of G- and F-actin into mRNA transcription. SRF activation is only partially characterized in non-transformed epithelial cells. Therefore, the impact of GTPases of the Rho family and changes in F-actin structures were analyzed in renal proximal tubular epithelial cells. Activation of SRF signaling was compared to the regulation of a known MKL1/SRF target gene, connective tissue growth factor (CTGF). In the human proximal tubular cell line HKC-8 overexpression of two actin mutants either favoring or preventing the formation of F-actin fibers regulated SRF-mediated transcription as well as CTGF expression. Only overexpression of constitutively active RhoA activated SRF-dependent gene expression whereas no effect was detected upon overexpression of Rac1 mutants. To elucidate the functional role of Rho kinases as downstream mediators of RhoA, pharmacological inhibition and genetic inhibition by transient siRNA knock down were compared. Upon stimulation with lysophosphatidic acid (LPA) Rho kinase inhibitors partially suppressed SRF-mediated transcription, whereas interference with Rho kinase expression by siRNA reduced activation of SRF, but barely affected CTGF expression. Together with the partial inhibition of CTGF expression by the pharmacological inhibitors Y27432 and H1154, Rho kinases seem to be less important in mediating RhoA signaling related to CTGF expression in HKC-8 epithelial cells. Short term pharmacological inhibition of Rac1 activity by EHT1864 reduced SRF-dependent CTGF expression in HKC-8 cells, but was overcome by a stimulatory effect after prolonged incubation after 4-6 h. Similarly, human primary cells of proximal but not of distal tubular origin showed inhibitory as well as stimulatory effects of Rac1 inhibition. Thus, RhoA signaling activates MKL1-SRF-mediated CTGF expression in proximal tubular cells, whereas Rac1 signaling is more complex with adaptive cellular responses.
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Affiliation(s)
- Klaudia Giehl
- Signal Transduction of Cellular Motility, Internal Medicine V, Justus-Liebig-University Giessen, Giessen, Germany
| | - Christof Keller
- Department of Nephrology and Hypertension, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Susanne Muehlich
- Walther Straub Institute of Pharmacology and Toxicology, Ludwig-Maximilians-University, Munich, Germany
| | - Margarete Goppelt-Struebe
- Department of Nephrology and Hypertension, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
- * E-mail:
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86
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Plessner M, Melak M, Chinchilla P, Baarlink C, Grosse R. Nuclear F-actin formation and reorganization upon cell spreading. J Biol Chem 2015; 290:11209-16. [PMID: 25759381 DOI: 10.1074/jbc.m114.627166] [Citation(s) in RCA: 184] [Impact Index Per Article: 20.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Indexed: 12/30/2022] Open
Abstract
We recently discovered signal-regulated nuclear actin network assembly. However, in contrast to cytoplasmic actin regulation, polymeric nuclear actin structures and functions remain only poorly understood. Here we describe a novel molecular tool to visualize real-time nuclear actin dynamics by targeting the Actin-Chromobody-TagGFP to the nucleus, thus establishing a nuclear Actin-Chromobody. Interestingly, we observe nuclear actin polymerization into dynamic filaments upon cell spreading and fibronectin stimulation, both of which appear to be triggered by integrin signaling. Furthermore, we show that nucleoskeletal proteins such as the LINC (linker of nucleoskeleton and cytoskeleton) complex and components of the nuclear lamina couple cell spreading or integrin activation by fibronectin to nuclear actin polymerization. Spreading-induced nuclear actin polymerization results in serum response factor (SRF)-mediated transcription through nuclear retention of myocardin-related transcription factor A (MRTF-A). Our results reveal a signaling pathway, which links integrin activation by extracellular matrix interaction to nuclear actin polymerization through the LINC complex, and therefore suggest a role for nuclear actin polymerization in the context of cellular adhesion and mechanosensing.
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Affiliation(s)
- Matthias Plessner
- From the Institute of Pharmacology, Biochemical-Pharmacological Center (BPC), University of Marburg, Karl-von-Frisch-Strasse 1, 35043 Marburg, Germany
| | - Michael Melak
- From the Institute of Pharmacology, Biochemical-Pharmacological Center (BPC), University of Marburg, Karl-von-Frisch-Strasse 1, 35043 Marburg, Germany
| | - Pilar Chinchilla
- From the Institute of Pharmacology, Biochemical-Pharmacological Center (BPC), University of Marburg, Karl-von-Frisch-Strasse 1, 35043 Marburg, Germany
| | - Christian Baarlink
- From the Institute of Pharmacology, Biochemical-Pharmacological Center (BPC), University of Marburg, Karl-von-Frisch-Strasse 1, 35043 Marburg, Germany
| | - Robert Grosse
- From the Institute of Pharmacology, Biochemical-Pharmacological Center (BPC), University of Marburg, Karl-von-Frisch-Strasse 1, 35043 Marburg, Germany
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87
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Volkman LE. Baculoviruses and nucleosome management. Virology 2015; 476:257-263. [PMID: 25569454 DOI: 10.1016/j.virol.2014.12.022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 12/09/2014] [Accepted: 12/10/2014] [Indexed: 11/30/2022]
Abstract
Negatively-supercoiled-ds DNA molecules, including the genomes of baculoviruses, spontaneously wrap around cores of histones to form nucleosomes when present within eukaryotic nuclei. Hence, nucleosome management should be essential for baculovirus genome replication and temporal regulation of transcription, but this has not been documented. Nucleosome mobilization is the dominion of ATP-dependent chromatin-remodeling complexes. SWI/SNF and INO80, two of the best-studied complexes, as well as chromatin modifier TIP60, all contain actin as a subunit. Retrospective analysis of results of AcMNPV time course experiments wherein actin polymerization was blocked by cytochalasin D drug treatment implicate actin-containing chromatin modifying complexes in decatenating baculovirus genomes, shutting down host transcription, and regulating late and very late phases of viral transcription. Moreover, virus-mediated nuclear localization of actin early during infection may contribute to nucleosome management.
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Affiliation(s)
- Loy E Volkman
- Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
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88
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Collard L, Herledan G, Pincini A, Guerci A, Randrianarison-Huetz V, Sotiropoulos A. Nuclear actin and myocardin-related transcription factors control disuse muscle atrophy through regulation of Srf activity. J Cell Sci 2014; 127:5157-63. [PMID: 25344251 DOI: 10.1242/jcs.155911] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Skeletal muscle atrophy is a debilitating process that is associated with a wide variety of conditions including inactivity, disease and aging. Here, we demonstrate that the actin, myocardin-related transcription factors and serum response factor (actin-Mrtf-Srf) pathway is specifically downregulated in the muscle atrophy that is induced through disuse in mice. We show in vivo that the abolition of mechanical signals leads to the rapid accumulation of G-actin in myonuclei and the export of the Srf coactivator Mrtf-A, resulting in a decrease of Mrtf-Srf-dependent transcription that contributes to atrophy. We demonstrate that inhibition of the actin-Mrtf-Srf axis through overexpression of nuclear non-polymerizable actin, through pharmacological inhibition of Mrtf-Srf and through muscle-specific Srf deletion worsens denervation-induced atrophy. Conversely, maintenance of high levels of activity of Srf or Mrtfs in denervated muscle, through overexpression of constitutively active derivatives, counteracts atrophy. Altogether, our data provide new mechanistic insights into the control of muscle mass upon disuse atrophy by the actin-Mrtf-Srf pathway, highlighting Srf as a key mediator of mechanotransduction in muscle.
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Affiliation(s)
- Laura Collard
- Inserm U1016, Institut Cochin, F-75014 Paris, France CNRS UMR8104, F-75014 Paris, France Université Paris Descartes, F-75006 Paris, France
| | - Gaëlle Herledan
- Inserm U1016, Institut Cochin, F-75014 Paris, France CNRS UMR8104, F-75014 Paris, France Université Paris Descartes, F-75006 Paris, France
| | - Alessandra Pincini
- Inserm U1016, Institut Cochin, F-75014 Paris, France CNRS UMR8104, F-75014 Paris, France Université Paris Descartes, F-75006 Paris, France
| | - Aline Guerci
- Inserm U1016, Institut Cochin, F-75014 Paris, France CNRS UMR8104, F-75014 Paris, France Université Paris Descartes, F-75006 Paris, France
| | - Voahangy Randrianarison-Huetz
- Inserm U1016, Institut Cochin, F-75014 Paris, France CNRS UMR8104, F-75014 Paris, France Université Paris Descartes, F-75006 Paris, France
| | - Athanassia Sotiropoulos
- Inserm U1016, Institut Cochin, F-75014 Paris, France CNRS UMR8104, F-75014 Paris, France Université Paris Descartes, F-75006 Paris, France
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89
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Lechuga S, Baranwal S, Li C, Naydenov NG, Kuemmerle JF, Dugina V, Chaponnier C, Ivanov AI. Loss of γ-cytoplasmic actin triggers myofibroblast transition of human epithelial cells. Mol Biol Cell 2014; 25:3133-46. [PMID: 25143399 PMCID: PMC4196865 DOI: 10.1091/mbc.e14-03-0815] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Transdifferentiation of epithelial cells into mesenchymal cells and myofibroblasts plays an important role in tumor progression and tissue fibrosis. Such epithelial plasticity is accompanied by dramatic reorganizations of the actin cytoskeleton, although mechanisms underlying cytoskeletal effects on epithelial transdifferentiation remain poorly understood. In the present study, we observed that selective siRNA-mediated knockdown of γ-cytoplasmic actin (γ-CYA), but not β-cytoplasmic actin, induced epithelial-to-myofibroblast transition (EMyT) of different epithelial cells. The EMyT manifested by increased expression of α-smooth muscle actin and other contractile proteins, along with inhibition of genes responsible for cell proliferation. Induction of EMyT in γ-CYA-depleted cells depended on activation of serum response factor and its cofactors, myocardial-related transcriptional factors A and B. Loss of γ-CYA stimulated formin-mediated actin polymerization and activation of Rho GTPase, which appear to be essential for EMyT induction. Our findings demonstrate a previously unanticipated, unique role of γ-CYA in regulating epithelial phenotype and suppression of EMyT that may be essential for cell differentiation and tissue fibrosis.
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Affiliation(s)
- Susana Lechuga
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA 23298
| | - Somesh Baranwal
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA 23298
| | - Chao Li
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA 23298
| | - Nayden G Naydenov
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA 23298
| | - John F Kuemmerle
- Department of Internal Medicine, Virginia Commonwealth University, Richmond, VA 23298
| | - Vera Dugina
- A.N. Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119991, Russia
| | - Christine Chaponnier
- Department of Pathology and Immunology, University Medical Center, University of Geneva, Geneva 4, Switzerland
| | - Andrei I Ivanov
- Department of Human and Molecular Genetics, Virginia Commonwealth University, Richmond, VA 23298 Virginia Institute of Molecular Medicine, Virginia Commonwealth University, Richmond, VA 23298 VCU Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298
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90
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The actin/MKL1 signalling pathway influences cell growth and gene expression through large-scale chromatin reorganization and histone post-translational modifications. Biochem J 2014; 461:257-68. [PMID: 24762104 DOI: 10.1042/bj20131240] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In addition to soluble factors, mechanical constraints and extracellular matrix stiffness are important regulators of cell fate that are mediated by cytoskeletal modifications. The EMT (epithelial-mesenchymal transition) that occurs during normal development and malignant progression is a typical example of the phenotypic switch associated with profound actin remodelling and changes in gene expression. For instance, actin dynamics control motile cell functions in EMT, in part, through regulating the subcellular localization of the myocardin-related transcription factor MKL1 (megakaryoblastic leukaemia translocation 1), a co-activator of SRF (serum-responsive factor). In the present paper, we show that MKL1 participates also to the control of the cellular switch between growth and quiescence. Experimental disconnection between MKL1 and G-actin (globular actin), by using an MKL1 mutant or enhancing the F (filamentous)-/G-actin ratio, generates a widely open chromatin state and a global increase in biosynthetic activity, classically associated with cell growth. Conversely, G-actin accumulation favours nuclear condensation and cell quiescence. These large-scale chromatin changes rely upon extensive histone modifications, exemplified by that of H3K9 (H3 Lys9) shifting from trimethylation, a heterochromatin mark, to acetylation, a mark of euchromatin. The present study provides the first evidence for a global reversible hetero/euchromatinization phenomenon triggered by the actin/MKL1 signalling pathway.
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91
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Kimura TE, Duggirala A, Hindmarch CCT, Hewer RC, Cui MZ, Newby AC, Bond M. Inhibition of Egr1 expression underlies the anti-mitogenic effects of cAMP in vascular smooth muscle cells. J Mol Cell Cardiol 2014; 72:9-19. [PMID: 24534707 PMCID: PMC4051994 DOI: 10.1016/j.yjmcc.2014.02.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 01/30/2014] [Accepted: 02/01/2014] [Indexed: 01/23/2023]
Abstract
AIMS Cyclic AMP inhibits vascular smooth muscle cell (VSMC) proliferation which is important in the aetiology of numerous vascular diseases. The anti-mitogenic properties of cAMP in VSMC are dependent on activation of protein kinase A (PKA) and exchange protein activated by cAMP (EPAC), but the mechanisms are unclear. METHODS AND RESULTS Selective agonists of PKA and EPAC synergistically inhibited Egr1 expression, which was essential for VSMC proliferation. Forskolin, adenosine, A2B receptor agonist BAY60-6583 and Cicaprost also inhibited Egr1 expression in VSMC but not in endothelial cells. Inhibition of Egr1 by cAMP was independent of cAMP response element binding protein (CREB) activity but dependent on inhibition of serum response element (SRE) activity. SRF binding to the Egr1 promoter was not modulated by cAMP stimulation. However, Egr1 expression was dependent on the SRF co-factors Elk1 and 4 but independent of MAL. Inhibition of SRE-dependent Egr1 expression was due to synergistic inhibition of Rac1 activity by PKA and EPAC, resulting in rapid cytoskeleton remodelling and nuclear export of ERK1/2. This was associated with de-phosphorylation of the SRF co-factor Elk1. CONCLUSION cAMP inhibits VSMC proliferation by rapidly inhibiting Egr1 expression. This occurs, at least in part, via inhibition of Rac1 activity leading to rapid actin-cytoskeleton remodelling, nuclear export of ERK1/2, impaired Elk1-phosphorylation and inhibition of SRE activity. This identifies one of the earliest mechanisms underlying the anti-mitogenic effects of cAMP in VSMC but not in endothelial cells, making it an attractive target for selective inhibition of VSMC proliferation.
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MESH Headings
- Adenosine/pharmacology
- Aminopyridines/pharmacology
- Animals
- Cell Proliferation/drug effects
- Colforsin/pharmacology
- Cyclic AMP/pharmacology
- Cyclic AMP Response Element-Binding Protein/genetics
- Cyclic AMP Response Element-Binding Protein/metabolism
- Cyclic AMP-Dependent Protein Kinases/genetics
- Cyclic AMP-Dependent Protein Kinases/metabolism
- Early Growth Response Protein 1/antagonists & inhibitors
- Early Growth Response Protein 1/genetics
- Early Growth Response Protein 1/metabolism
- Epoprostenol/analogs & derivatives
- Epoprostenol/pharmacology
- Gene Expression Regulation
- Guanine Nucleotide Exchange Factors/genetics
- Guanine Nucleotide Exchange Factors/metabolism
- Human Umbilical Vein Endothelial Cells/cytology
- Human Umbilical Vein Endothelial Cells/drug effects
- Human Umbilical Vein Endothelial Cells/metabolism
- Male
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/cytology
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Organ Specificity
- Primary Cell Culture
- Protein Binding
- Rats
- Rats, Sprague-Dawley
- Serum Response Factor/genetics
- Serum Response Factor/metabolism
- Signal Transduction
- ets-Domain Protein Elk-1/genetics
- ets-Domain Protein Elk-1/metabolism
- rac1 GTP-Binding Protein/genetics
- rac1 GTP-Binding Protein/metabolism
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Affiliation(s)
- Tomomi E Kimura
- Bristol Heart Institute, University of Bristol, Bristol BS2 8HW, UK
| | - Aparna Duggirala
- Bristol Heart Institute, University of Bristol, Bristol BS2 8HW, UK
| | - Charles C T Hindmarch
- Laboratory for Integrative Neuroscience & Endocrinology, University of Bristol, Bristol BS2 8HW, UK; University of Malaya, Department of Physiology, Faculty of Medicine, Kuala Lumpur, Malaysia
| | - Richard C Hewer
- Bristol Heart Institute, University of Bristol, Bristol BS2 8HW, UK
| | - Mei-Zhen Cui
- Department of Pathobiology, College of Veterinary Medicine, The University of Tennessee, USA
| | - Andrew C Newby
- Bristol Heart Institute, University of Bristol, Bristol BS2 8HW, UK
| | - Mark Bond
- Bristol Heart Institute, University of Bristol, Bristol BS2 8HW, UK.
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92
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Salvany L, Muller J, Guccione E, Rørth P. The core and conserved role of MAL is homeostatic regulation of actin levels. Genes Dev 2014; 28:1048-53. [PMID: 24831700 PMCID: PMC4035534 DOI: 10.1101/gad.237743.114] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The transcription cofactor MAL is regulated by actin dynamics and, together with its DNA-binding partner, SRF, is required for invasive cell migration. Salvany et al. show in Drosophila and human cellular models that actin is the key target that must be regulated by MAL/SRF for invasive cell migration. By regulating MAL/SRF, actin feeds back on the production of actin mRNA to ensure sufficient actin supply. Actin and MAL thus form a homeostatic feedback system that provides the foundation for actin dynamics required for complex cell behavior. The transcription cofactor MAL is regulated by free actin levels and thus by actin dynamics. MAL, together with its DNA-binding partner, SRF, is required for invasive cell migration and in experimental metastasis. Although MAL/SRF has many targets, we provide genetic evidence in both Drosophila and human cellular models that actin is the key target that must be regulated by MAL/SRF for invasive cell migration. By regulating MAL/SRF activity, actin protein feeds back on production of actin mRNA to ensure sufficient supply of actin. This constitutes a dedicated homeostatic feedback system that provides a foundation for cellular actin dynamics.
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Affiliation(s)
- Lara Salvany
- Institute of Molecular and Cell Biology, Singapore 138673, Singapore
| | - Julius Muller
- Institute of Molecular and Cell Biology, Singapore 138673, Singapore
| | - Ernesto Guccione
- Institute of Molecular and Cell Biology, Singapore 138673, Singapore
| | - Pernille Rørth
- Institute of Molecular and Cell Biology, Singapore 138673, Singapore
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93
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MRTF-A controls vessel growth and maturation by increasing the expression of CCN1 and CCN2. Nat Commun 2014; 5:3970. [DOI: 10.1038/ncomms4970] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 04/28/2014] [Indexed: 12/24/2022] Open
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94
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Kerdivel G, Boudot A, Habauzit D, Percevault F, Demay F, Pakdel F, Flouriot G. Activation of the MKL1/actin signaling pathway induces hormonal escape in estrogen-responsive breast cancer cell lines. Mol Cell Endocrinol 2014; 390:34-44. [PMID: 24721635 DOI: 10.1016/j.mce.2014.03.009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 03/31/2014] [Accepted: 03/31/2014] [Indexed: 02/07/2023]
Abstract
Estrogen receptor alpha (ERα) is generally considered to be a good prognostic marker because almost 70% of ERα-positive tumors respond to anti-hormone therapies. Unfortunately, during cancer progression, mammary tumors can escape from estrogen control, resulting in resistance to treatment. In this study, we demonstrate that activation of the actin/megakaryoblastic leukemia 1 (MKL1) signaling pathway promotes the hormonal escape of estrogen-sensitive breast cancer cell lines. The actin/MKL1 signaling pathway is silenced in differentiated ERα-positive breast cancer MCF-7 and T47D cell lines and active in ERα-negative HMT-3522 T4-2 and MDA-MB-231 breast cancer cells, which have undergone epithelial-mesenchymal transition. We showed that MKL1 activation in MCF-7 cells, either by modulating actin dynamics or using MKL1 mutants, down-regulates ERα expression and abolishes E2-dependent cell growth. Interestingly, the constitutively active form of MKL1 represses PR and HER2 expression in these cells and increases the expression of HB-EGF, TGFβ, and amphiregulin growth factors in an E2-independent manner. The resulting expression profile (ER-, PR-, HER2-) typically corresponds to the triple-negative breast cancer expression profile.
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MESH Headings
- Actins/metabolism
- Antineoplastic Agents, Hormonal/pharmacology
- Breast Neoplasms/drug therapy
- Breast Neoplasms/metabolism
- DNA-Binding Proteins/metabolism
- Drug Resistance, Neoplasm
- Estradiol/physiology
- Estrogen Receptor alpha/genetics
- Estrogen Receptor alpha/metabolism
- Female
- Humans
- MCF-7 Cells
- Neoplasms, Hormone-Dependent/drug therapy
- Neoplasms, Hormone-Dependent/metabolism
- Oncogene Proteins, Fusion/metabolism
- Receptor, ErbB-2/genetics
- Receptor, ErbB-2/metabolism
- Receptors, Progesterone/genetics
- Receptors, Progesterone/metabolism
- Signal Transduction
- Tamoxifen/pharmacology
- Trans-Activators
- Transcription, Genetic
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Affiliation(s)
- Gwenneg Kerdivel
- University of Rennes 1, Institut de Recherche en Santé Environnement et Travail, IRSET, INSERM U1085, Team TREC, Biosit, Rennes, France
| | - Antoine Boudot
- University of Rennes 1, Institut de Recherche en Santé Environnement et Travail, IRSET, INSERM U1085, Team TREC, Biosit, Rennes, France
| | - Denis Habauzit
- University of Rennes 1, Institut de Recherche en Santé Environnement et Travail, IRSET, INSERM U1085, Team TREC, Biosit, Rennes, France
| | - Frederic Percevault
- University of Rennes 1, Institut de Recherche en Santé Environnement et Travail, IRSET, INSERM U1085, Team TREC, Biosit, Rennes, France
| | - Florence Demay
- University of Rennes 1, Institut de Recherche en Santé Environnement et Travail, IRSET, INSERM U1085, Team TREC, Biosit, Rennes, France
| | - Farzad Pakdel
- University of Rennes 1, Institut de Recherche en Santé Environnement et Travail, IRSET, INSERM U1085, Team TREC, Biosit, Rennes, France
| | - Gilles Flouriot
- University of Rennes 1, Institut de Recherche en Santé Environnement et Travail, IRSET, INSERM U1085, Team TREC, Biosit, Rennes, France.
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95
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Itoh K, Ossipova O, Sokol SY. GEF-H1 functions in apical constriction and cell intercalations and is essential for vertebrate neural tube closure. J Cell Sci 2014; 127:2542-53. [PMID: 24681784 DOI: 10.1242/jcs.146811] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Rho family GTPases regulate many morphogenetic processes during vertebrate development including neural tube closure. Here we report a function for GEF-H1/Lfc/ArhGEF2, a RhoA-specific guanine nucleotide exchange factor that functions in neurulation in Xenopus embryos. Morpholino-mediated depletion of GEF-H1 resulted in severe neural tube defects, which were rescued by GEF-H1 RNA. Lineage tracing of GEF-H1 morphants at different developmental stages revealed abnormal cell intercalation and apical constriction, suggesting that GEF-H1 regulates these cell behaviors. Molecular marker analysis documented defects in myosin II light chain (MLC) phosphorylation, Rab11 and F-actin accumulation in GEF-H1-depleted cells. In gain-of-function studies, overexpressed GEF-H1 induced Rho-associated kinase-dependent ectopic apical constriction - marked by apical accumulation of phosphorylated MLC, γ-tubulin and F-actin in superficial ectoderm - and stimulated apical protrusive activity of deep ectoderm cells. Taken together, our observations newly identify functions of GEF-H1 in morphogenetic movements that lead to neural tube closure.
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Affiliation(s)
- Keiji Itoh
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Olga Ossipova
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Sergei Y Sokol
- Department of Developmental and Regenerative Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
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96
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Rajakylä EK, Vartiainen MK. Rho, nuclear actin, and actin-binding proteins in the regulation of transcription and gene expression. Small GTPases 2014; 5:e27539. [PMID: 24603113 DOI: 10.4161/sgtp.27539] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Actin cytoskeleton is one of the main targets of Rho GTPases, which act as molecular switches on many signaling pathways. During the past decade, actin has emerged as an important regulator of gene expression. Nuclear actin plays a key role in transcription, chromatin remodeling, and pre-mRNA processing. In addition, the "status" of the actin cytoskeleton is used as a signaling intermediate by at least the MKL1-SRF and Hippo-pathways, which culminate in the transcriptional regulation of cytoskeletal and growth-promoting genes, respectively. Rho GTPases may therefore regulate gene expression by controlling either cytoplasmic or nuclear actin dynamics. Although the regulation of nuclear actin polymerization is still poorly understood, many actin-binding proteins, which are downstream effectors of Rho, are found in the nuclear compartment. In this review, we discuss the possible mechanisms and key proteins that may mediate the transcriptional regulation by Rho GTPases through actin.
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Affiliation(s)
- Eeva Kaisa Rajakylä
- Program in Cell and Molecular Biology; Institute of Biotechnology; University of Helsinki; Helsinki, Finland
| | - Maria K Vartiainen
- Program in Cell and Molecular Biology; Institute of Biotechnology; University of Helsinki; Helsinki, Finland
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97
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Simiczyjew A, Mazur AJ, Popow-Woźniak A, Malicka-Błaszkiewicz M, Nowak D. Effect of overexpression of β- and γ-actin isoforms on actin cytoskeleton organization and migration of human colon cancer cells. Histochem Cell Biol 2014; 142:307-22. [PMID: 24682235 PMCID: PMC4133152 DOI: 10.1007/s00418-014-1199-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/09/2014] [Indexed: 01/26/2023]
Abstract
Actins are eukaryotic proteins, which are involved in diverse cellular functions including muscle contraction, cell motility, adhesion and maintenance of cell shape. Cytoplasmic actin isoforms β and γ are ubiquitously expressed and essential for cell functioning. However, their unique contributions are not very well understood. The aim of this study was to determine the effect of β- and γ-actin overexpression on the migration capacity and actin cytoskeleton organization of human colon adenocarcinoma BE cells. In cells overexpressing β- or γ-actin, distinct cytoskeletal actin rearrangements were observed under the laser scanning confocal microscope. Overexpressed actins localized at the submembranous region of the cell body, especially near to the leading edge and on the tips of pseudopodia. The cells transfected with plasmids containing cDNA for β- or γ-actin were characterized by increased migration and invasion capacities. However, the migration velocity was statistically significantly higher only in the case of γ-actin overexpressing cells. In conclusion, the increased level of β- or γ-actin leads to actin cytoskeletal remodeling followed by an increase in migration and invasion capacities of human colon BE cells. These data suggest that expression of both actin isoforms has an impact on cancer cell motility, with the subtle predominance of γ-actin, and may influence invasiveness of human colon cancer.
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Affiliation(s)
- Aleksandra Simiczyjew
- Department of Cell Pathology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Antonina Joanna Mazur
- Department of Cell Pathology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Agnieszka Popow-Woźniak
- Department of Cell Pathology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Maria Malicka-Błaszkiewicz
- Department of Cell Pathology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
| | - Dorota Nowak
- Department of Cell Pathology, Faculty of Biotechnology, University of Wrocław, Joliot-Curie 14a, 50-383 Wrocław, Poland
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98
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Abstract
Arp5 suppresses myocardin activity through both direct binding to myocardin and binding to SRF to prevent transcriptional activation of myogenic genes by the myocardin–SRF complex. Myocardin (Myocd) and Myocd-related transcription factors (MRTFs) are robust coactivators of serum response factor (SRF). RPEL motifs are monomeric globular actin (G-actin) binding elements that regulate MRTF localization and activity. However, the function of the RPEL motif in Myocd is largely unknown because of its low affinity for G-actin. Here, we demonstrated that the Myocd RPEL motif bound to actin-related protein 5 (Arp5) instead of conventional actin, resulting in a significant suppression of Myocd activity. In addition, Arp5 bound to a DNA binding domain of SRF via its C-terminal sequence and prevented the association of the Myocd–SRF complex with the promoter regions of smooth muscle genes. Well-differentiated smooth muscle cells mainly expressed a specific splicing variant of arp5; therefore, the protein level of Arp5 was markedly reduced by partial messenger RNA decay and translational suppression. In dedifferentiated smooth muscle cells, Arp5 knockdown restored the differentiated phenotype via Myocd activation. Thus, Arp5 is a key regulator of Myocd activity.
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Affiliation(s)
- Tsuyoshi Morita
- Department of Neuroscience, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
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99
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Lamon S, Wallace MA, Russell AP. The STARS signaling pathway: a key regulator of skeletal muscle function. Pflugers Arch 2014; 466:1659-71. [DOI: 10.1007/s00424-014-1475-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2013] [Revised: 02/04/2014] [Accepted: 02/05/2014] [Indexed: 01/08/2023]
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100
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The transcription factor serum response factor stimulates axon regeneration through cytoplasmic localization and cofilin interaction. J Neurosci 2014; 33:18836-48. [PMID: 24285890 DOI: 10.1523/jneurosci.3029-13.2013] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Axonal injury generates growth inert retraction bulbs with dynamic cytoskeletal properties that are severely compromised. Conversion of "frozen" retraction bulbs into actively progressing growth cones is a major aim in axon regeneration. Here we report that murine serum response factor (SRF), a gene regulator linked to the actin cytoskeleton, modulates growth cone actin dynamics during axon regeneration. In regeneration-competent facial motoneurons, Srf deletion inhibited axonal regeneration. In wild-type mice after nerve injury, SRF translocated from the nucleus to the cytoplasm, suggesting a cytoplasmic SRF function in axonal regeneration. Indeed, adenoviral overexpression of cytoplasmic SRF (SRF-ΔNLS-GFP) stimulated axonal sprouting and facial nerve regeneration in vivo. In primary central and peripheral neurons, SRF-ΔNLS-GFP stimulated neurite outgrowth, branch formation, and growth cone morphology. Furthermore, we uncovered a link between SRF and the actin-severing factor cofilin during axonal regeneration in vivo. Facial nerve axotomy increased the total cofilin abundance and also nuclear localization of phosphorylated cofilin in a subpopulation of lesioned motoneurons. This cytoplasmic-to-nucleus translocation of P-cofilin upon axotomy was reduced in motoneurons expressing SRF-ΔNLS-GFP. Finally, we demonstrate that cytoplasmic SRF and cofilin formed a reciprocal regulatory unit. Overexpression of cytoplasmic SRF reduced cofilin phosphorylation and vice versa: overexpression of cofilin inhibited SRF phosphorylation. Therefore, a regulatory loop consisting of SRF and cofilin might take part in reactivating actin dynamics in growth-inert retraction bulbs and facilitating axon regeneration.
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