1
|
Laporte D, Massoni-Laporte A, Lefranc C, Dompierre J, Mauboules D, Nsamba ET, Royou A, Gal L, Schuldiner M, Gupta ML, Sagot I. A stable microtubule bundle formed through an orchestrated multistep process controls quiescence exit. eLife 2024; 12:RP89958. [PMID: 38527106 PMCID: PMC10963028 DOI: 10.7554/elife.89958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/27/2024] Open
Abstract
Cells fine-tune microtubule assembly in both space and time to give rise to distinct edifices with specific cellular functions. In proliferating cells, microtubules are highly dynamics, and proliferation cessation often leads to their stabilization. One of the most stable microtubule structures identified to date is the nuclear bundle assembled in quiescent yeast. In this article, we characterize the original multistep process driving the assembly of this structure. This Aurora B-dependent mechanism follows a precise temporality that relies on the sequential actions of kinesin-14, kinesin-5, and involves both microtubule-kinetochore and kinetochore-kinetochore interactions. Upon quiescence exit, the microtubule bundle is disassembled via a cooperative process involving kinesin-8 and its full disassembly is required prior to cells re-entry into proliferation. Overall, our study provides the first description, at the molecular scale, of the entire life cycle of a stable microtubule structure in vivo and sheds light on its physiological function.
Collapse
Affiliation(s)
| | | | | | | | | | - Emmanuel T Nsamba
- Genetics, Development, and Cell Biology, Iowa State UniversityAmesUnited States
| | - Anne Royou
- Univ. Bordeaux, CNRS, IBGC, UMR 5095BordeauxFrance
| | - Lihi Gal
- Department of Molecular Genetics, Weizmann Institute of ScienceRehovotIsrael
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of ScienceRehovotIsrael
| | - Mohan L Gupta
- Genetics, Development, and Cell Biology, Iowa State UniversityAmesUnited States
| | | |
Collapse
|
2
|
Schuster T, Geiger H. Septins in Stem Cells. Front Cell Dev Biol 2021; 9:801507. [PMID: 34957123 PMCID: PMC8695968 DOI: 10.3389/fcell.2021.801507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 11/24/2021] [Indexed: 12/01/2022] Open
Abstract
Septins were first described in yeast. Due to extensive research in non-yeast cells, Septins are now recognized across all species as important players in the regulation of the cytoskeleton, in the establishment of polarity, for migration, vesicular trafficking and scaffolding. Stem cells are primarily quiescent cells, and this actively maintained quiescent state is critical for proper stem cell function. Equally important though, stem cells undergo symmetric or asymmetric division, which is likely linked to the level of symmetry found in the mother stem cell. Due to the ability to organize barriers and be able to break symmetry in cells, Septins are thought to have a significant impact on organizing quiescence as well as the mode (symmetric vs asymmetric) of stem cell division to affect self-renewal versus differentiation. Mechanisms of regulating mammalian quiescence and symmetry breaking by Septins are though still somewhat elusive. Within this overview article, we summarize current knowledge on the role of Septins in stem cells ranging from yeast to mice especially with respect to quiescence and asymmetric division, with a special focus on hematopoietic stem cells.
Collapse
Affiliation(s)
| | - Hartmut Geiger
- Institute of Molecular Medicine, Ulm University, Ulm, Germany
| |
Collapse
|
3
|
Sun S, Gresham D. Cellular quiescence in budding yeast. Yeast 2021; 38:12-29. [PMID: 33350503 DOI: 10.1002/yea.3545] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 12/11/2020] [Accepted: 12/14/2020] [Indexed: 12/20/2022] Open
Abstract
Cellular quiescence, the temporary and reversible exit from proliferative growth, is the predominant state of all cells. However, our understanding of the biological processes and molecular mechanisms that underlie cell quiescence remains incomplete. As with the mitotic cell cycle, budding and fission yeast are preeminent model systems for studying cellular quiescence owing to their rich experimental toolboxes and the evolutionary conservation across eukaryotes of pathways and processes that control quiescence. Here, we review current knowledge of cell quiescence in budding yeast and how it pertains to cellular quiescence in other organisms, including multicellular animals. Quiescence entails large-scale remodeling of virtually every cellular process, organelle, gene expression, and metabolic state that is executed dynamically as cells undergo the initiation, maintenance, and exit from quiescence. We review these major transitions, our current understanding of their molecular bases, and highlight unresolved questions. We summarize the primary methods employed for quiescence studies in yeast and discuss their relative merits. Understanding cell quiescence has important consequences for human disease as quiescent single-celled microbes are notoriously difficult to kill and quiescent human cells play important roles in diseases such as cancer. We argue that research on cellular quiescence will be accelerated through the adoption of common criteria, and methods, for defining cell quiescence. An integrated approach to studying cell quiescence, and a focus on the behavior of individual cells, will yield new insights into the pathways and processes that underlie cell quiescence leading to a more complete understanding of the life cycle of cells. TAKE AWAY: Quiescent cells are viable cells that have reversibly exited the cell cycle Quiescence is induced in response to a variety of nutrient starvation signals Quiescence is executed dynamically through three phases: initiation, maintenance, and exit Quiescence entails large-scale remodeling of gene expression, organelles, and metabolism Single-cell approaches are required to address heterogeneity among quiescent cells.
Collapse
Affiliation(s)
- Siyu Sun
- Center for Genomics and Systems Biology, New York University, New York, New York, 10003, USA.,Department of Biology, New York University, New York, New York, 10003, USA
| | - David Gresham
- Center for Genomics and Systems Biology, New York University, New York, New York, 10003, USA.,Department of Biology, New York University, New York, New York, 10003, USA
| |
Collapse
|
4
|
Coulon S, Vaurs M. Telomeric Transcription and Telomere Rearrangements in Quiescent Cells. J Mol Biol 2020; 432:4220-4231. [PMID: 32061930 DOI: 10.1016/j.jmb.2020.01.034] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 01/29/2020] [Accepted: 01/30/2020] [Indexed: 02/07/2023]
Abstract
Despite the condensed nature of terminal sequences, the telomeres are transcribed into a group of noncoding RNAs, including the TElomeric Repeat-containing RNA (TERRA). Since the discovery of TERRA, its evolutionary conserved function has been confirmed, and its involvement in telomere length regulation, heterochromatin establishment, and telomere recombination has been demonstrated. We previously reported that TERRA is upregulated in quiescent fission yeast cells, although the global transcription is highly reduced. Elevated telomeric transcription was also detected when telomeres detach from the nuclear periphery. These intriguing observations unveil unexpected facets of telomeric transcription in arrested cells. In this review, we present the different aspects of TERRA transcription during quiescence and discuss their implications for telomere maintenance and cell fate.
Collapse
Affiliation(s)
- Stéphane Coulon
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Equipe labellisée Ligue contre le Cancer, Marseille, F-13009, France.
| | - Mélina Vaurs
- CNRS, INSERM, Aix Marseille Univ, Institut Paoli-Calmettes, CRCM, Equipe labellisée Ligue contre le Cancer, Marseille, F-13009, France
| |
Collapse
|
5
|
Heimlicher MB, Bächler M, Liu M, Ibeneche-Nnewihe C, Florin EL, Hoenger A, Brunner D. Reversible solidification of fission yeast cytoplasm after prolonged nutrient starvation. J Cell Sci 2019; 132:jcs.231688. [PMID: 31558680 PMCID: PMC6857596 DOI: 10.1242/jcs.231688] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 09/20/2019] [Indexed: 12/19/2022] Open
Abstract
Cells depend on a highly ordered organisation of their content and must develop strategies to maintain the anisotropic distribution of organelles during periods of nutrient shortage. One of these strategies is to solidify the cytoplasm, which was observed in bacteria and yeast cells with acutely interrupted energy production. Here, we describe a different type of cytoplasm solidification fission yeast cells switch to, after having run out of nutrients during multiple days in culture. It provides the most profound reversible cytoplasmic solidification of yeast cells described to date. Our data exclude the previously proposed mechanisms for cytoplasm solidification in yeasts and suggest a mechanism that immobilises cellular components in a size-dependent manner. We provide experimental evidence that, in addition to time, cells use intrinsic nutrients and energy sources to reach this state. Such cytoplasmic solidification may provide a robust means to protect cellular architecture in dormant cells. Summary: After prolonged quiescence, fission yeast cell populations switch state to immobilise subcellular components much more profoundly than cells experiencing acute energy depletion.
Collapse
Affiliation(s)
- Maria B Heimlicher
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Mirjam Bächler
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| | - Minghua Liu
- Dept. of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, UCB-0347, Boulder, CO 80309, USA
| | - Chieze Ibeneche-Nnewihe
- Center for Nonlinear Dynamics and Department of Physics, University of Texas at Austin, Austin, TX 78712, USA
| | - Ernst-Ludwig Florin
- Center for Nonlinear Dynamics and Department of Physics, University of Texas at Austin, Austin, TX 78712, USA
| | - Andreas Hoenger
- Dept. of Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, UCB-0347, Boulder, CO 80309, USA
| | - Damian Brunner
- Department of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, 8057 Zurich, Switzerland
| |
Collapse
|
6
|
Liu M, Heimlicher MB, Bächler M, Ibeneche-Nnewihe CC, Florin EL, Brunner D, Hoenger A. Glucose starvation triggers filamentous septin assemblies in an S. pombe septin-2 deletion mutant. Biol Open 2019; 8:8/1/bio037622. [PMID: 30602528 PMCID: PMC6361201 DOI: 10.1242/bio.037622] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Using correlative light and electron microscopy (CLEM), we studied the intracellular organization by of glucose-starved fission yeast cells (Schizosaccharomyces pombe) with regards to the localization of septin proteins throughout the cytoplasm. Thereby, we found that for cells carrying a deletion of the gene encoding septin-2 (spn2Δ), starvation causes a GFP-tagged version of septin-3 (spn3-GFP) and family members, to assemble into a single, prominent filamentous structure. It was previously shown that during exponential growth, spn2Δ cells form septin-3 polymers. However, the polymers we observed during exponential growth are different from the spn3p-GFP structure we observed in starved cells. Using CLEM, in combination with anti-GFP immunolabeling on plastic-sections, we could assign spn3p-GFP to the filaments we have found in EM pictures. Besides septin-3, these filamentous assemblies most likely also contain septin-1 as an RFP-tagged version of this protein forms a very similar structure in starved spn2Δ cells. Our data correlate phase-contrast and fluorescence microscopy with electron micrographs of plastic-embedded cells, and further on with detailed views of tomographic 3D reconstructions. Cryo-electron microscopy of spn2Δ cells in vitrified sections revealed a very distinct overall morphology of the spn3p-GFP assembly. The fine-structured, regular density pattern suggests the presence of assembled septin-3 filaments that are clearly different from F-actin bundles. Furthermore, we found that starvation causes substantial mitochondria fission, together with massive decoration of their outer membrane by ribosomes.
Collapse
Affiliation(s)
- Minghua Liu
- University of Colorado at Boulder, Department of Molecular, Cellular and Developmental Biology, UCB-0347, Boulder, CO 80309, USA
| | - Maria B Heimlicher
- University of Zürich, Department of Molecular Life Sciences, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Mirjam Bächler
- University of Zürich, Department of Molecular Life Sciences, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Chieze C Ibeneche-Nnewihe
- University of Texas at Austin, Center for Nonlinear Dynamics and Department of Physics, Austin, TX 78712, USA
| | - Ernst-Ludwig Florin
- University of Texas at Austin, Center for Nonlinear Dynamics and Department of Physics, Austin, TX 78712, USA
| | - Damian Brunner
- University of Zürich, Department of Molecular Life Sciences, Winterthurerstrasse 190, 8057 Zürich, Switzerland
| | - Andreas Hoenger
- University of Colorado at Boulder, Department of Molecular, Cellular and Developmental Biology, UCB-0347, Boulder, CO 80309, USA
| |
Collapse
|
7
|
Sagot I, Laporte D. The cell biology of quiescent yeast – a diversity of individual scenarios. J Cell Sci 2019; 132:132/1/jcs213025. [DOI: 10.1242/jcs.213025] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
ABSTRACT
Most cells, from unicellular to complex organisms, spend part of their life in quiescence, a temporary non-proliferating state. Although central for a variety of essential processes including tissue homeostasis, development and aging, quiescence is poorly understood. In fact, quiescence encompasses various cellular situations depending on the cell type and the environmental niche. Quiescent cell properties also evolve with time, adding another layer of complexity. Studying quiescence is, above all, limited by the fact that a quiescent cell can be recognized as such only after having proved that it is capable of re-proliferating. Recent cellular biology studies in yeast have reported the relocalization of hundreds of proteins and the reorganization of several cellular machineries upon proliferation cessation. These works have revealed that quiescent cells can display various properties, shedding light on a plethora of individual behaviors. The deciphering of the molecular mechanisms beyond these reorganizations, together with the understanding of their cellular functions, have begun to provide insights into the physiology of quiescent cells. In this Review, we discuss recent findings and emerging concepts in Saccharomyces cerevisiae quiescent cell biology.
Collapse
Affiliation(s)
- Isabelle Sagot
- Centre National de la Recherche Scientifique, Université de Bordeaux-Institut de Biochimie et Génétique Cellulaires, UMR5095-33077 Bordeaux cedex, France
| | - Damien Laporte
- Centre National de la Recherche Scientifique, Université de Bordeaux-Institut de Biochimie et Génétique Cellulaires, UMR5095-33077 Bordeaux cedex, France
| |
Collapse
|
8
|
Laporte D, Gouleme L, Jimenez L, Khemiri I, Sagot I. Mitochondria reorganization upon proliferation arrest predicts individual yeast cell fate. eLife 2018; 7:35685. [PMID: 30299253 PMCID: PMC6177259 DOI: 10.7554/elife.35685] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 09/14/2018] [Indexed: 02/06/2023] Open
Abstract
Most cells spend the majority of their life in a non-proliferating state. When proliferation cessation is irreversible, cells are senescent. By contrast, if the arrest is only temporary, cells are defined as quiescent. These cellular states are hardly distinguishable without triggering proliferation resumption, hampering thus the study of quiescent cells properties. Here we show that quiescent and senescent yeast cells are recognizable based on their mitochondrial network morphology. Indeed, while quiescent yeast cells display numerous small vesicular mitochondria, senescent cells exhibit few globular mitochondria. This allowed us to reconsider at the individual-cell level, properties previously attributed to quiescent cells using population-based approaches. We demonstrate that cell’s propensity to enter quiescence is not influenced by replicative age, volume or density. Overall, our findings reveal that quiescent cells are not all identical but that their ability to survive is significantly improved when they exhibit the specific reorganization of several cellular machineries.
Collapse
Affiliation(s)
- Damien Laporte
- Centre National de la Recherche Scientifique, Université de Bordeaux - Institut de Biochimie et Génétique Cellulaires, Bordeaux, France
| | - Laëtitia Gouleme
- Centre National de la Recherche Scientifique, Université de Bordeaux - Institut de Biochimie et Génétique Cellulaires, Bordeaux, France
| | - Laure Jimenez
- Centre National de la Recherche Scientifique, Université de Bordeaux - Institut de Biochimie et Génétique Cellulaires, Bordeaux, France
| | - Ines Khemiri
- Centre National de la Recherche Scientifique, Université de Bordeaux - Institut de Biochimie et Génétique Cellulaires, Bordeaux, France
| | - Isabelle Sagot
- Centre National de la Recherche Scientifique, Université de Bordeaux - Institut de Biochimie et Génétique Cellulaires, Bordeaux, France
| |
Collapse
|
9
|
Takenaka K, Tanabe T, Kawamukai M, Matsuo Y. Overexpression of the transcription factor Rst2 in Schizosaccharomyces pombe indicates growth defect, mitotic defects, and microtubule disorder. Biosci Biotechnol Biochem 2018; 82:247-257. [PMID: 29316864 DOI: 10.1080/09168451.2017.1415126] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
In Schizosaccharomyces pombe, the transcription factor Rst2 regulates ste11 in meiosis and fbp1 in glucogenesis downstream of the cyclic adenosine monophosphate (cAMP)-dependent protein kinase (PKA) pathway. Here, we demonstrate that Rst2 regulates additional cellular events. Overexpressed Rst2 elevated the frequency of oval, bent, branched, septated, and multi-septated cells. Cells showed normal nuclear divisions but exhibited abnormal nuclear organization at low frequency. In oval cells, microtubules were curved but they were rescued by the deletion of mal3. Since growth defect was not rescued by mal3 deletion, we argue that it is regulated independently. Loss of functional Pka1 exaggerated growth defect upon Rst2 overexpression because its downregulation by Pka1 was lost. Overexpression of Rst2 also caused sensitivity to KCl and CaCl2. These findings suggest that, in addition to meiosis and glucogenesis, Rst2 is involved in cellular events such as regulation of cell growth, cell morphology, mitosis progression, microtubules structure, nuclear structure, and stress response.
Collapse
Affiliation(s)
- Kouhei Takenaka
- a Department of Life Science and Biotechnology, Faculty of Life and Environmental Science , Shimane University , Matsue , Japan
| | - Takuma Tanabe
- a Department of Life Science and Biotechnology, Faculty of Life and Environmental Science , Shimane University , Matsue , Japan
| | - Makoto Kawamukai
- a Department of Life Science and Biotechnology, Faculty of Life and Environmental Science , Shimane University , Matsue , Japan
| | - Yasuhiro Matsuo
- a Department of Life Science and Biotechnology, Faculty of Life and Environmental Science , Shimane University , Matsue , Japan
| |
Collapse
|
10
|
Pitaval A, Senger F, Letort G, Gidrol X, Guyon L, Sillibourne J, Théry M. Microtubule stabilization drives 3D centrosome migration to initiate primary ciliogenesis. J Cell Biol 2017; 216:3713-3728. [PMID: 28993469 PMCID: PMC5674878 DOI: 10.1083/jcb.201610039] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 06/02/2017] [Accepted: 08/17/2017] [Indexed: 01/09/2023] Open
Abstract
The classical view of centrosome decentering and migration to the cell periphery during ciliogenesis is that it is pulled toward its final destination. Here, Pitaval et al. argue that microtubule stabilization in the early stages of ciliogenesis generates pushing forces that propel the centrosome toward the apical pole. Primary cilia are sensory organelles located at the cell surface. Their assembly is primed by centrosome migration to the apical surface, yet surprisingly little is known about this initiating step. To gain insight into the mechanisms driving centrosome migration, we exploited the reproducibility of cell architecture on adhesive micropatterns to investigate the cytoskeletal remodeling supporting it. Microtubule network densification and bundling, with the transient formation of an array of cold-stable microtubules, and actin cytoskeleton asymmetrical contraction participate in concert to drive apical centrosome migration. The distal appendage protein Cep164 appears to be a key actor involved in the cytoskeleton remodeling and centrosome migration, whereas intraflagellar transport 88’s role seems to be restricted to axoneme elongation. Together, our data elucidate the hitherto unexplored mechanism of centrosome migration and show that it is driven by the increase and clustering of mechanical forces to push the centrosome toward the cell apical pole.
Collapse
Affiliation(s)
- Amandine Pitaval
- UMR_S 1038, Biomics Lab, University Grenoble-Alpes, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Institut National de la Santé et de la Recherche, Institut de Biosciences et Biotechnologies de Grenoble, Grenoble, France.,UMR 5168, CytoMorpho Lab, University Grenoble-Alpes, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Institut de Biosciences et Biotechnologies de Grenoble, Grenoble, France
| | - Fabrice Senger
- UMR 5168, CytoMorpho Lab, University Grenoble-Alpes, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Institut de Biosciences et Biotechnologies de Grenoble, Grenoble, France
| | - Gaëlle Letort
- UMR 5168, CytoMorpho Lab, University Grenoble-Alpes, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Institut de Biosciences et Biotechnologies de Grenoble, Grenoble, France
| | - Xavier Gidrol
- UMR_S 1038, Biomics Lab, University Grenoble-Alpes, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Institut National de la Santé et de la Recherche, Institut de Biosciences et Biotechnologies de Grenoble, Grenoble, France
| | - Laurent Guyon
- UMR_S 1036, Biologie du Cancer et de l'Infection, University Grenoble-Alpes, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Institut National de la Santé et de la Recherche, Institut de Biosciences et Biotechnologies de Grenoble, Grenoble, France
| | - James Sillibourne
- UMR 5168, CytoMorpho Lab, University Grenoble-Alpes, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Institut de Biosciences et Biotechnologies de Grenoble, Grenoble, France .,UMRS 1160, CytoMorpho Lab, University Paris Diderot, Institut National de la Santé et de la Recherche, Hôpital Saint Louis, Institut Universitaire d'Hematologie, Paris, France
| | - Manuel Théry
- UMR 5168, CytoMorpho Lab, University Grenoble-Alpes, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, Institut National de la Recherche Agronomique, Centre National de la Recherche Scientifique, Institut de Biosciences et Biotechnologies de Grenoble, Grenoble, France .,UMRS 1160, CytoMorpho Lab, University Paris Diderot, Institut National de la Santé et de la Recherche, Hôpital Saint Louis, Institut Universitaire d'Hematologie, Paris, France
| |
Collapse
|
11
|
Abstract
Most cells in nature are not actively dividing, yet are able to return to the cell cycle given the appropriate environmental signals. There is now ample evidence that quiescent G0 cells are not shut-down but still metabolically and transcriptionally active. Quiescent cells must maintain a basal transcriptional capacity to maintain transcripts and proteins necessary for survival. This implies a tight control over RNA polymerases: RNA pol II for mRNA transcription during G0, but especially RNA pol I and RNA pol III to maintain an appropriate level of structural RNAs, raising the possibility that specific transcriptional control mechanisms evolved in quiescent cells. In accordance with this, we recently discovered that RNA interference is necessary to control RNA polymerase I transcription during G0. While this mini-review focuses on yeast model organisms (Saccharomyces cerevisiae and Schizosaccharomyces pombe), parallels are drawn to other eukaryotes and mammalian systems, in particular stem cells.
Collapse
Affiliation(s)
- Benjamin Roche
- a Cold Spring Harbor Laboratory , Cold Spring Harbor , NY , USA
| | - Benoit Arcangioli
- b Genome Dynamics Unit , UMR 3525 CNRS, Institut Pasteur, 25-28 rue du Docteur Roux , Paris , France
| | - Robert Martienssen
- a Cold Spring Harbor Laboratory , Cold Spring Harbor , NY , USA.,c Howard Hughes Medical Institute-Gordon and Betty Moore Foundation (HHMI-GBM) Investigator , NY , USA
| |
Collapse
|
12
|
Shukla N, Osmani AH, Osmani SA. Microtubules are reversibly depolymerized in response to changing gaseous microenvironments within Aspergillus nidulans biofilms. Mol Biol Cell 2017; 28:634-644. [PMID: 28057761 PMCID: PMC5328622 DOI: 10.1091/mbc.e16-10-0750] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 12/16/2016] [Accepted: 12/29/2016] [Indexed: 12/20/2022] Open
Abstract
How microtubules (MTs) are regulated during fungal biofilm formation is unknown. By tracking MT +end-binding proteins (+TIPS) in Aspergillus nidulans, we find that MTs are regulated to depolymerize within forming fungal biofilms. During this process, EB1, dynein, and ClipA form transient fibrous and then bar-like structures, novel configurations for +TIPS. Cells also respond in an autonomous manner, with cells separated by a septum able to maintain different MT dynamics. Surprisingly, all cells with depolymerized MTs rapidly repolymerize their MTs after air exchange above the static culture medium of biofilms. Although the specific gasotransmitter for this biofilm response is not known, we find that addition of hydrogen sulfide gas to growing cells recapitulates all aspects of reversible MT depolymerization and transient formation of +TIPs bars. However, as biofilms mature, physical removal of part of the biofilm is required to promote MT repolymerization, which occurs at the new biofilm edge. We further show MT depolymerization within biofilms is regulated by the SrbA hypoxic transcription factor and that without SrbA, MTs are maintained as biofilms form. This reveals a new mode of MT regulation in response to changing gaseous biofilm microenvironments, which could contribute to the unique characteristics of fungal biofilms in medical and industrial settings.
Collapse
Affiliation(s)
- Nandini Shukla
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210.,Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Aysha H Osmani
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| | - Stephen A Osmani
- Ohio State Biochemistry Program, The Ohio State University, Columbus, OH 43210 .,Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210
| |
Collapse
|
13
|
Calcium signaling mechanisms disrupt the cytoskeleton of primary astrocytes and neurons exposed to diphenylditelluride. Biochim Biophys Acta Gen Subj 2016; 1860:2510-2520. [PMID: 27475002 DOI: 10.1016/j.bbagen.2016.07.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 06/20/2016] [Accepted: 07/25/2016] [Indexed: 02/08/2023]
Abstract
BACKGROUND Diphenylditelluride (PhTe)2 is a potent neurotoxin disrupting the homeostasis of the cytoskeleton. METHODS Cultured astrocytes and neurons were incubated with (PhTe)2, receptor antagonists and enzyme inhibitors followed by measurement of the incorporation of [32P]orthophosphate into intermediate filaments (IFs). RESULTS (PhTe)2 caused hyperphosphorylation of glial fibrillary acidic protein (GFAP), vimentin and neurofilament subunits (NFL, NFM and NFH) from primary astrocytes and neurons, respectively. These mechanisms were mediated by N-methyl-d-aspartate (NMDA) receptors, L-type voltage-dependent calcium channels (L-VDCCs) as well as metabotropic glutamate receptors upstream of phospholipase C (PLC). Upregulated Ca(2+) influx activated protein kinase A (PKA) and protein kinase C (PKC) in astrocytes causing hyperphosphorylation of GFAP and vimentin. Hyperphosphorylated (IF) together with RhoA-activated stress fiber formation, disrupted the cytoskeleton leading to altered cell morphology. In neurons, the high intracellular Ca(2+) levels activated the MAPKs, Erk and p38MAPK, beyond PKA and PKC, provoking hyperphosphorylation of NFM, NFH and NFL. CONCLUSIONS Our findings support that intracellular Ca(2+) is one of the crucial signals that modulate the action of (PhTe)2 in isolated cortical astrocytes and neurons modulating the response of the cytoskeleton against the insult. GENERAL SIGNIFICANCE Cytoskeletal misregulation is associated with neurodegeneration. This compound could be a valuable tool to induce molecular changes similar to those found in different pathologies of the brain.
Collapse
|