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Ramakanth S, Kennedy T, Yalcinkaya B, Neupane S, Tadic N, Buchler NE, Argüello-Miranda O. Deep learning-driven imaging of cell division and cell growth across an entire eukaryotic life cycle. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.25.591211. [PMID: 38712227 PMCID: PMC11071524 DOI: 10.1101/2024.04.25.591211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
The life cycle of biomedical and agriculturally relevant eukaryotic microorganisms involves complex transitions between proliferative and non-proliferative states such as dormancy, mating, meiosis, and cell division. New drugs, pesticides, and vaccines can be created by targeting specific life cycle stages of parasites and pathogens. However, defining the structure of a microbial life cycle often relies on partial observations that are theoretically assembled in an ideal life cycle path. To create a more quantitative approach to studying complete eukaryotic life cycles, we generated a deep learning-driven imaging framework to track microorganisms across sexually reproducing generations. Our approach combines microfluidic culturing, life cycle stage-specific segmentation of microscopy images using convolutional neural networks, and a novel cell tracking algorithm, FIEST, based on enhancing the overlap of single cell masks in consecutive images through deep learning video frame interpolation. As proof of principle, we used this approach to quantitatively image and compare cell growth and cell cycle regulation across the sexual life cycle of Saccharomyces cerevisiae . We developed a fluorescent reporter system based on a fluorescently labeled Whi5 protein, the yeast analog of mammalian Rb, and a new High-Cdk1 activity sensor, LiCHI, designed to report during DNA replication, mitosis, meiotic homologous recombination, meiosis I, and meiosis II. We found that cell growth preceded the exit from non-proliferative states such as mitotic G1, pre-meiotic G1, and the G0 spore state during germination. A decrease in the total cell concentration of Whi5 characterized the exit from non-proliferative states, which is consistent with a Whi5 dilution model. The nuclear accumulation of Whi5 was developmentally regulated, being at its highest during meiotic exit and spore formation. The temporal coordination of cell division and growth was not significantly different across three sexually reproducing generations. Our framework could be used to quantitatively characterize other single-cell eukaryotic life cycles that remain incompletely described. An off-the-shelf user interface Yeastvision provides free access to our image processing and single-cell tracking algorithms.
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Gal C, Cochrane GA, Morgan BA, Rallis C, Bähler J, Whitehall SK. The longevity and reversibility of quiescence in Schizosaccharomyces pombe are dependent upon the HIRA histone chaperone. Cell Cycle 2023; 22:1921-1936. [PMID: 37635373 PMCID: PMC10599175 DOI: 10.1080/15384101.2023.2249705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 08/04/2023] [Accepted: 08/09/2023] [Indexed: 08/29/2023] Open
Abstract
Quiescence (G0) is a reversible non-dividing state that facilitates cellular survival in adverse conditions. Here, we demonstrate that the HIRA histone chaperone complex is required for the reversibility and longevity of nitrogen starvation-induced quiescence in Schizosaccharomyces pombe. The HIRA protein, Hip1 is not required for entry into G0 or the induction of autophagy. Although hip1Δ cells retain metabolic activity in G0, they rapidly lose the ability to resume proliferation. After a short period in G0 (1 day), hip1Δ mutants can resume cell growth in response to the restoration of a nitrogen source but do not efficiently reenter the vegetative cell cycle. This correlates with a failure to induce the expression of MBF transcription factor-dependent genes that are critical for S phase. In addition, hip1Δ G0 cells rapidly progress to a senescent state in which they can no longer re-initiate growth following nitrogen source restoration. Analysis of a conditional hip1 allele is consistent with these findings and indicates that HIRA is required for efficient exit from quiescence and prevents an irreversible cell cycle arrest.
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Affiliation(s)
- Csenge Gal
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Grace A. Cochrane
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Brian A. Morgan
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Charalampos Rallis
- School of Biological and Behavioural Sciences, Queen Mary University of London, London, UK
| | - Jürg Bähler
- Department of Genetics, Evolution and Environment and Institute of Healthy Ageing, University College London, London, UK
| | - Simon K. Whitehall
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
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3
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Abdualmjid RJ, Sergi CM. Mitochondrial Dysfunction and Induction of Apoptosis in Hepatocellular Carcinoma and Cholangiocarcinoma Cell Lines by Thymoquinone. Int J Mol Sci 2022; 23:ijms232314669. [PMID: 36498999 PMCID: PMC9737800 DOI: 10.3390/ijms232314669] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 11/16/2022] [Accepted: 11/17/2022] [Indexed: 11/25/2022] Open
Abstract
Thymoquinone (TQ), a plant-based bioactive constituent derived from the volatile oil of Nigella sativa, has been shown to possess some anti-neoplastic activities. The present study aimed to investigate the mitochondria and apoptosis observed when TQ is applied against hepatocellular carcinoma (HepG2) and cholangiocarcinoma (HuCCT1) cells, two of the most common primary tumors of the liver. All cell lines were treated with increasing concentrations of TQ for varying durations. The anti-proliferative effect of TQ was measured using the methoxyphenyl-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay and resulted in dose- and time-dependent growth inhibition in both cell lines. Cell cycle, apoptosis, and assessment of mitochondria viability by morphology assessment and evaluation of the mitochondrial membrane potential were investigated. The present study confirms that TQ caused cell cycle arrest at different phases and induced apoptosis in both cell lines. A systematic review of rodent animal models was also carried out. Overall, our data seem to represent the most robust results, suggesting that TQ possesses promising therapeutic potential as an anti-tumor agent for the treatment of hepatocellular carcinoma and cholangiocarcinoma.
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Affiliation(s)
- Reem J. Abdualmjid
- Department of Lab. Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2B7, Canada
| | - Consolato M. Sergi
- Department of Lab. Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2B7, Canada
- Anatomic Pathology, Children’s Hospital of Eastern Ontario (CHEO), University of Ottawa, Ottawa, ON K1H 8L1, Canada
- Correspondence: ; Tel.: +1-613-737-7600 (ext. 2427); Fax: +1-613-738-4837
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4
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Ramón-Landreau M, Sánchez-Puelles C, López-Sánchez N, Lozano-Ureña A, Llabrés-Mas AM, Frade JM. E2F4DN Transgenic Mice: A Tool for the Evaluation of E2F4 as a Therapeutic Target in Neuropathology and Brain Aging. Int J Mol Sci 2022; 23:ijms232012093. [PMID: 36292945 PMCID: PMC9603043 DOI: 10.3390/ijms232012093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 10/04/2022] [Accepted: 10/05/2022] [Indexed: 12/03/2022] Open
Abstract
E2F4 was initially described as a transcription factor with a key function in the regulation of cell quiescence. Nevertheless, a number of recent studies have established that E2F4 can also play a relevant role in cell and tissue homeostasis, as well as tissue regeneration. For these non-canonical functions, E2F4 can also act in the cytoplasm, where it is able to interact with many homeostatic and synaptic regulators. Since E2F4 is expressed in the nervous system, it may fulfill a crucial role in brain function and homeostasis, being a promising multifactorial target for neurodegenerative diseases and brain aging. The regulation of E2F4 is complex, as it can be chemically modified through acetylation, from which we present evidence in the brain, as well as methylation, and phosphorylation. The phosphorylation of E2F4 within a conserved threonine motif induces cell cycle re-entry in neurons, while a dominant negative form of E2F4 (E2F4DN), in which the conserved threonines have been substituted by alanines, has been shown to act as a multifactorial therapeutic agent for Alzheimer’s disease (AD). We generated transgenic mice neuronally expressing E2F4DN. We have recently shown using this mouse strain that expression of E2F4DN in 5xFAD mice, a known murine model of AD, improved cognitive function, reduced neuronal tetraploidization, and induced a transcriptional program consistent with modulation of amyloid-β (Aβ) peptide proteostasis and brain homeostasis recovery. 5xFAD/E2F4DN mice also showed reduced microgliosis and astrogliosis in both the cerebral cortex and hippocampus at 3-6 months of age. Here, we analyzed the immune response in 1 year-old 5xFAD/E2F4DN mice, concluding that reduced microgliosis and astrogliosis is maintained at this late stage. In addition, the expression of E2F4DN also reduced age-associated microgliosis in wild-type mice, thus stressing its role as a brain homeostatic agent. We conclude that E2F4DN transgenic mice represent a promising tool for the evaluation of E2F4 as a therapeutic target in neuropathology and brain aging.
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Affiliation(s)
- Morgan Ramón-Landreau
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute, Consejo Superior de Investigaciones Científicas, 28002 Madrid, Spain
| | - Cristina Sánchez-Puelles
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute, Consejo Superior de Investigaciones Científicas, 28002 Madrid, Spain
| | - Noelia López-Sánchez
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute, Consejo Superior de Investigaciones Científicas, 28002 Madrid, Spain
| | - Anna Lozano-Ureña
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute, Consejo Superior de Investigaciones Científicas, 28002 Madrid, Spain
| | - Aina M. Llabrés-Mas
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute, Consejo Superior de Investigaciones Científicas, 28002 Madrid, Spain
| | - José M. Frade
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute, Consejo Superior de Investigaciones Científicas, 28002 Madrid, Spain
- Cajal International Neuroscience Center, Consejo Superior de Investigaciones Científicas, UAH Science and Technology Campus, Avenida León 1, 28805 Alcalá de Henares, Spain
- Correspondence: ; Tel.: +34-91-585-4740
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5
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Leonov A, Feldman R, Piano A, Arlia-Ciommo A, Junio JAB, Orfanos E, Tafakori T, Lutchman V, Mohammad K, Elsaser S, Orfali S, Rajen H, Titorenko VI. Diverse geroprotectors differently affect a mechanism linking cellular aging to cellular quiescence in budding yeast. Oncotarget 2022; 13:918-943. [PMID: 35937500 PMCID: PMC9348708 DOI: 10.18632/oncotarget.28256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Accepted: 07/01/2022] [Indexed: 11/25/2022] Open
Affiliation(s)
- Anna Leonov
- Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada
| | - Rachel Feldman
- Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada
| | - Amanda Piano
- Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada
| | | | | | - Emmanuel Orfanos
- Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada
| | - Tala Tafakori
- Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada
| | - Vicky Lutchman
- Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada
| | - Karamat Mohammad
- Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada
| | - Sarah Elsaser
- Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada
| | - Sandra Orfali
- Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada
| | - Harshvardhan Rajen
- Department of Biology, Concordia University, Montreal, Quebec H4B 1R6, Canada
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6
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Argüello-Miranda O, Marchand AJ, Kennedy T, Russo MAX, Noh J. Cell cycle-independent integration of stress signals by Xbp1 promotes Non-G1/G0 quiescence entry. J Cell Biol 2022; 221:212720. [PMID: 34694336 PMCID: PMC8548912 DOI: 10.1083/jcb.202103171] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 08/27/2021] [Accepted: 10/05/2021] [Indexed: 12/15/2022] Open
Abstract
Cellular quiescence is a nonproliferative state required for cell survival under stress and during development. In most quiescent cells, proliferation is stopped in a reversible state of low Cdk1 kinase activity; in many organisms, however, quiescent states with high-Cdk1 activity can also be established through still uncharacterized stress or developmental mechanisms. Here, we used a microfluidics approach coupled to phenotypic classification by machine learning to identify stress pathways associated with starvation-triggered high-Cdk1 quiescent states in Saccharomyces cerevisiae. We found that low- and high-Cdk1 quiescent states shared a core of stress-associated processes, such as autophagy, protein aggregation, and mitochondrial up-regulation, but differed in the nuclear accumulation of the stress transcription factors Xbp1, Gln3, and Sfp1. The decision between low- or high-Cdk1 quiescence was controlled by cell cycle-independent accumulation of Xbp1, which acted as a time-delayed integrator of the duration of stress stimuli. Our results show how cell cycle-independent stress-activated factors promote cellular quiescence outside G1/G0.
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Affiliation(s)
- Orlando Argüello-Miranda
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX.,Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Ashley J Marchand
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Taylor Kennedy
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX.,School of Natural Sciences and Mathematics, University of Texas at Dallas, Richardson, TX
| | - Marielle A X Russo
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX
| | - Jungsik Noh
- Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX
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7
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López-Sánchez N, Garrido-García A, Ramón-Landreau M, Cano-Daganzo V, Frade JM. E2F4-Based Gene Therapy Mitigates the Phenotype of the Alzheimer's Disease Mouse Model 5xFAD. Neurotherapeutics 2021; 18:2484-2503. [PMID: 34766258 PMCID: PMC8804140 DOI: 10.1007/s13311-021-01151-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/22/2021] [Indexed: 12/16/2022] Open
Abstract
After decades of unfruitful work, no effective therapies are available for Alzheimer's disease (AD), likely due to its complex etiology that requires a multifactorial therapeutic approach. We have recently shown using transgenic mice that E2 factor 4 (E2F4), a transcription factor that regulates cell quiescence and tissue homeostasis, and controls gene networks affected in AD, represents a good candidate for a multifactorial targeting of AD. Here we show that the expression of a dominant negative form of human E2F4 (hE2F4DN), unable to become phosphorylated in a Thr-conserved motif known to modulate E2F4 activity, is an effective and safe AD multifactorial therapeutic agent. Neuronal expression of hE2F4DN in homozygous 5xFAD (h5xFAD) mice after systemic administration of an AAV.PHP.B-hSyn1.hE2F4DN vector reduced the production and accumulation of Aβ in the hippocampus, attenuated reactive astrocytosis and microgliosis, abolished neuronal tetraploidization, and prevented cognitive impairment evaluated by Y-maze and Morris water maze, without triggering side effects. This treatment also reversed other alterations observed in h5xFAD mice such as paw-clasping behavior and body weight loss. Our results indicate that E2F4DN-based gene therapy is a promising therapeutic approach against AD.
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Affiliation(s)
- Noelia López-Sánchez
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute, 28002, Madrid, Spain
| | - Alberto Garrido-García
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute, 28002, Madrid, Spain
| | - Morgan Ramón-Landreau
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute, 28002, Madrid, Spain
| | - Vanesa Cano-Daganzo
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute, 28002, Madrid, Spain
| | - José M Frade
- Department of Molecular, Cellular and Developmental Neurobiology, Cajal Institute, 28002, Madrid, Spain.
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8
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Zhu J, Huang Z, Yang F, Zhu M, Cao J, Chen J, Lin Y, Guo S, Li J, Liu Z. Cadmium disturbs epigenetic modification and induces DNA damage in mouse preimplantation embryos. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 219:112306. [PMID: 33984557 DOI: 10.1016/j.ecoenv.2021.112306] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 04/27/2021] [Accepted: 05/02/2021] [Indexed: 06/12/2023]
Abstract
Cadmium is an environmental pollutant that has extensive deleterious effects on the reproductive system. However, the mechanisms underlying the effects of cadmium on preimplantation embryos are unclear. Here, we used a mouse model to investigate the effects of maternal cadmium (32 mg/l) exposure in drinking water for 2 days on early embryonic development, and studied the mechanisms associated with epigenetic modifications and DNA damage induced by oxidative stress. We observed that maternal cadmium exposure impaired preimplantation embryo development by inducing embryo death, fragmentation, or developmental blockade. After cadmium exposure, the most survived embryos were at the 8-cell stage, which were used for all measurements. Histone acetylation, not methylation, was disturbed by increasing histone deacetylase 1 (HDAC1) levels after cadmium exposure. Cadmium also disrupted DNA methylation of H19; however genomic DNA methylation can be normally reprogrammed in embryos. Furthermore, cadmium increased reactive oxygen species (ROS) levels and DNA damage, and partly inhibited gene expression related to DNA repair. The distribution and activity of mitochondria was increased; therefore, embryos maintain intracellular homeostasis for survival. Collectively, our findings revealed that maternal cadmium exposure impairs preimplantation embryo development by disturbing the epigenetic modification and inducing DNA damage.
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Affiliation(s)
- Jiaqiao Zhu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu, PR China.
| | - Zhutao Huang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, PR China; Laboratory Animal Center, Xuzhou Medical University, Xuzhou, Jiangsu, PR China
| | - Fan Yang
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, PR China; Shen Zhen Heng Sheng Hospital, Southern Medical University, Shen Zhen, Guangdong, PR China
| | - Min Zhu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, PR China
| | - Jiangqin Cao
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, PR China
| | - Jiali Chen
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, PR China
| | - Yan Lin
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, PR China
| | - Shuai Guo
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, PR China
| | - Junwei Li
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, PR China
| | - Zongping Liu
- College of Veterinary Medicine, Yangzhou University, Yangzhou, Jiangsu, PR China; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, Jiangsu, PR China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu, PR China.
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9
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Replication-independent instability of Friedreich's ataxia GAA repeats during chronological aging. Proc Natl Acad Sci U S A 2021; 118:2013080118. [PMID: 33495349 PMCID: PMC7865128 DOI: 10.1073/pnas.2013080118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The inheritance of long (GAA)n repeats in the frataxin gene causes the debilitating neurodegenerative disease Friedreich’s ataxia. Subsequent expansions of these repeats throughout a patient’s lifetime in the affected tissues, like the nervous system, may contribute to disease onset. We developed an experimental model to characterize the mechanisms of repeat instability in nondividing cells to better understand how mutations can occur as cells age chronologically. We show that repeats can expand in nondividing cells. Notably, however, large deletions are the major type of repeat-mediated genome instability in nondividing cells, implicating the loss of important genetic material with aging in the progression of Friedreich’s ataxia. Nearly 50 hereditary diseases result from the inheritance of abnormally long repetitive DNA microsatellites. While it was originally believed that the size of inherited repeats is the key factor in disease development, it has become clear that somatic instability of these repeats throughout an individual’s lifetime strongly contributes to disease onset and progression. Importantly, somatic instability is commonly observed in terminally differentiated, postmitotic cells, such as neurons. To unravel the mechanisms of repeat instability in nondividing cells, we created an experimental system to analyze the mutability of Friedreich’s ataxia (GAA)n repeats during chronological aging of quiescent Saccharomyces cerevisiae. Unexpectedly, we found that the predominant repeat-mediated mutation in nondividing cells is large-scale deletions encompassing parts, or the entirety, of the repeat and adjacent regions. These deletions are caused by breakage at the repeat mediated by mismatch repair (MMR) complexes MutSβ and MutLα and DNA endonuclease Rad1, followed by end-resection by Exo1 and repair of the resulting double-strand breaks (DSBs) via nonhomologous end joining. We also observed repeat-mediated gene conversions as a result of DSB repair via ectopic homologous recombination during chronological aging. Repeat expansions accrue during chronological aging as well—particularly in the absence of MMR-induced DSBs. These expansions depend on the processivity of DNA polymerase δ while being counteracted by Exo1 and MutSβ, implicating nick repair. Altogether, these findings show that the mechanisms and types of (GAA)n repeat instability differ dramatically between dividing and nondividing cells, suggesting that distinct repeat-mediated mutations in terminally differentiated somatic cells might influence Friedreich’s ataxia pathogenesis.
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10
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Lee PH, Osley M. Chromatin structure restricts origin utilization when quiescent cells re-enter the cell cycle. Nucleic Acids Res 2021; 49:864-878. [PMID: 33367871 PMCID: PMC7826286 DOI: 10.1093/nar/gkaa1148] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 11/04/2020] [Accepted: 12/21/2020] [Indexed: 12/12/2022] Open
Abstract
Quiescent cells reside in G0 phase, which is characterized by the absence of cell growth and proliferation. These cells remain viable and re-enter the cell cycle when prompted by appropriate signals. Using a budding yeast model of cellular quiescence, we investigated the program that initiated DNA replication when these G0 cells resumed growth. Quiescent cells contained very low levels of replication initiation factors, and their entry into S phase was delayed until these factors were re-synthesized. A longer S phase in these cells correlated with the activation of fewer origins of replication compared to G1 cells. The chromatin structure around inactive origins in G0 cells showed increased H3 occupancy and decreased nucleosome positioning compared to the same origins in G1 cells, inhibiting the origin binding of the Mcm4 subunit of the MCM licensing factor. Thus, quiescent yeast cells are under-licensed during their re-entry into S phase.
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Affiliation(s)
- Po-Hsuen Lee
- Department of Molecular Genetics and Microbiology University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
| | - Mary Ann Osley
- Department of Molecular Genetics and Microbiology University of New Mexico Health Sciences Center, Albuquerque, NM 87131, USA
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11
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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.
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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
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12
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High-Throughput Flow Cytometry Combined with Genetic Analysis Brings New Insights into the Understanding of Chromatin Regulation of Cellular Quiescence. Int J Mol Sci 2020; 21:ijms21239022. [PMID: 33260998 PMCID: PMC7729564 DOI: 10.3390/ijms21239022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 11/19/2020] [Accepted: 11/23/2020] [Indexed: 11/21/2022] Open
Abstract
Cellular quiescence is a reversible differentiation state when cells are changing the gene expression program to reduce metabolic functions and adapt to a new cellular environment. When fission yeast cells are deprived of nitrogen in the absence of any mating partner, cells can reversibly arrest in a differentiated G0-like cellular state, called quiescence. This change is accompanied by a marked alteration of nuclear organization and a global reduction of transcription. Using high-throughput flow cytometry combined with genetic analysis, we describe the results of a comprehensive screen for genes encoding chromatin components and regulators that are required for the entry and the maintenance of cellular quiescence. We show that the histone acetylase and deacetylase complexes, SAGA and Rpd3, have key roles both for G0 entry and survival during quiescence. We reveal a novel function for the Ino80 nucleosome remodeling complex in cellular quiescence. Finally, we demonstrate that components of the MRN complex, Rad3, the nonhomologous end-joining, and nucleotide excision DNA repair pathways are essential for viability in G0.
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13
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Li P, Hao Z, Zeng F. Tumor suppressor stars in yeast G1/S transition. Curr Genet 2020; 67:207-212. [PMID: 33175222 DOI: 10.1007/s00294-020-01126-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2020] [Revised: 10/22/2020] [Accepted: 10/28/2020] [Indexed: 12/11/2022]
Abstract
Yeast is one of the best-understood biological systems for genetic research. Over the last 40 years, geneticists have striven to search for homologues of tumor suppressors in yeast to simplify cancer research. The star tumor suppressor p21, downstream target of p53, is one of the primary factors on the START point through negatively regulating CycD/E-CDK, the yeast counterpart Cln3-Cdk1. Not like yeast Whi5 that was identified as the analog of the retinoblastoma tumor suppressor protein (Rb) and hence promoted to uncover the mechanism of its cancer suppression, homologue of p21 had not been found in yeast. Our lab identified Cip1 in budding yeast as a novel negative regulator of G1-Cdk1 and proposed that Cip1 is an analog of human p21. Recently, we demonstrated a dual repressive function of Cip1 on START timing via the redundant Cln3 and Ccr4 pathways. This work in yeast may help clarify the complex regulation in human p53-p21 signaling cascade. In this review, we will discuss the yeast paralogs of star tumor suppressors in the control of G1/S transition and present the new findings in this field.
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Affiliation(s)
- Pan Li
- College of Life Sciences, Hebei Agricultural University, Baoding, 071001, Hebei, China
| | - Zhimin Hao
- College of Life Sciences, Hebei Agricultural University, Baoding, 071001, Hebei, China
| | - Fanli Zeng
- College of Life Sciences, Hebei Agricultural University, Baoding, 071001, Hebei, China.
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14
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Mohammad K, Baratang Junio JA, Tafakori T, Orfanos E, Titorenko VI. Mechanisms that Link Chronological Aging to Cellular Quiescence in Budding Yeast. Int J Mol Sci 2020; 21:ijms21134717. [PMID: 32630624 PMCID: PMC7369985 DOI: 10.3390/ijms21134717] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 06/27/2020] [Accepted: 06/30/2020] [Indexed: 12/28/2022] Open
Abstract
After Saccharomyces cerevisiae cells cultured in a medium with glucose consume glucose, the sub-populations of quiescent and non-quiescent cells develop in the budding yeast culture. An age-related chronology of quiescent and non-quiescent yeast cells within this culture is discussed here. We also describe various hallmarks of quiescent and non-quiescent yeast cells. A complex aging-associated program underlies cellular quiescence in budding yeast. This quiescence program includes a cascade of consecutive cellular events orchestrated by an intricate signaling network. We examine here how caloric restriction, a low-calorie diet that extends lifespan and healthspan in yeast and other eukaryotes, influences the cellular quiescence program in S. cerevisiae. One of the main objectives of this review is to stimulate an exploration of the mechanisms that link cellular quiescence to chronological aging of budding yeast. Yeast chronological aging is defined by the length of time during which a yeast cell remains viable after its growth and division are arrested, and it becomes quiescent. We propose a hypothesis on how caloric restriction can slow chronological aging of S. cerevisiae by altering the chronology and properties of quiescent cells. Our hypothesis posits that caloric restriction delays yeast chronological aging by targeting four different processes within quiescent cells.
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15
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Sun S, Baryshnikova A, Brandt N, Gresham D. Genetic interaction profiles of regulatory kinases differ between environmental conditions and cellular states. Mol Syst Biol 2020; 16:e9167. [PMID: 32449603 PMCID: PMC7247079 DOI: 10.15252/msb.20199167] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Revised: 03/18/2020] [Accepted: 03/31/2020] [Indexed: 01/13/2023] Open
Abstract
Cell growth and quiescence in eukaryotic cells is controlled by an evolutionarily conserved network of signaling pathways. Signal transduction networks operate to modulate a wide range of cellular processes and physiological properties when cells exit proliferative growth and initiate a quiescent state. How signaling networks function to respond to diverse signals that result in cell cycle exit and establishment of a quiescent state is poorly understood. Here, we studied the function of signaling pathways in quiescent cells using global genetic interaction mapping in the model eukaryotic cell, Saccharomyces cerevisiae (budding yeast). We performed pooled analysis of genotypes using molecular barcode sequencing (Bar-seq) to test the role of ~4,000 gene deletion mutants and ~12,000 pairwise interactions between all non-essential genes and the protein kinase genes TOR1, RIM15, and PHO85 in three different nutrient-restricted conditions in both proliferative and quiescent cells. We detect up to 10-fold more genetic interactions in quiescent cells than proliferative cells. We find that both individual gene effects and genetic interaction profiles vary depending on the specific pro-quiescence signal. The master regulator of quiescence, RIM15, shows distinct genetic interaction profiles in response to different starvation signals. However, vacuole-related functions show consistent genetic interactions with RIM15 in response to different starvation signals, suggesting that RIM15 integrates diverse signals to maintain protein homeostasis in quiescent cells. Our study expands genome-wide genetic interaction profiling to additional conditions, and phenotypes, and highlights the conditional dependence of epistasis.
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Affiliation(s)
- Siyu Sun
- Center for Genomics and Systems BiologyNew York UniversityNew YorkNYUSA
- Department of BiologyNew York UniversityNew YorkNYUSA
| | | | - Nathan Brandt
- Center for Genomics and Systems BiologyNew York UniversityNew YorkNYUSA
- Department of BiologyNew York UniversityNew YorkNYUSA
| | - David Gresham
- Center for Genomics and Systems BiologyNew York UniversityNew YorkNYUSA
- Department of BiologyNew York UniversityNew YorkNYUSA
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16
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Kishkevich A, Cooke SL, Harris MRA, de Bruin RAM. Gcn5 and Rpd3 have a limited role in the regulation of cell cycle transcripts during the G1 and S phases in Saccharomyces cerevisiae. Sci Rep 2019; 9:10686. [PMID: 31337860 PMCID: PMC6650506 DOI: 10.1038/s41598-019-47170-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 06/26/2019] [Indexed: 01/12/2023] Open
Abstract
Activation of cell cycle regulated transcription during the G1-to-S transition initiates S phase entry and cell cycle commitment. The molecular mechanisms involving G1/S transcriptional regulation are well established and have been shown to be evolutionary conserved from yeast to humans. Previous work has suggested that changes to the chromatin state, specifically through histone acetylation, has an important role in the regulation of G1/S transcription in both yeast and human cells. Here we investigate the role of histone acetylation in G1/S transcriptional regulation in the budding yeast Saccharomyces cerevisiae. Our work shows that histone acetylation at specific sites at G1/S target gene promoters peaks at the G1-to-S transition, coinciding with their peak transcription levels. Acetylation at G1/S target promoters is significantly reduced upon deletion of the previously implicated histone acetyltransferase Gcn5, but G1/S cell cycle regulated transcription is largely unaffected. The histone deacetylase Rpd3, suggested to have a role in Whi5-dependent repression, is required for full repression of G1/S target genes in the G1 and S phases. However, in the context of transcriptionally active levels during the G1-to-S transition, this seems to play a minor role in the regulation of cell cycle transcription. Our data suggests that histone acetylation might modulate the amplitude of G1/S cell cycle regulated transcription in Saccharomyces cerevisiae, but has a limited role in its overall regulation.
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Affiliation(s)
- A Kishkevich
- MRC Laboratory for Molecular Cell Biology University College London, WC1E 6BT, London, UK
- Department of Biochemistry, University of Oxford, OX3 1QU, Oxford, UK
| | - S L Cooke
- MRC Laboratory for Molecular Cell Biology University College London, WC1E 6BT, London, UK
| | - M R A Harris
- MRC Laboratory for Molecular Cell Biology University College London, WC1E 6BT, London, UK
| | - R A M de Bruin
- MRC Laboratory for Molecular Cell Biology University College London, WC1E 6BT, London, UK.
- UCL Cancer Institute, University College London, WC1E 6BT, London, UK.
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17
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Vermeersch L, Perez-Samper G, Cerulus B, Jariani A, Gallone B, Voordeckers K, Steensels J, Verstrepen KJ. On the duration of the microbial lag phase. Curr Genet 2019; 65:721-727. [PMID: 30666394 PMCID: PMC6510831 DOI: 10.1007/s00294-019-00938-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 01/11/2019] [Accepted: 01/11/2019] [Indexed: 12/19/2022]
Abstract
When faced with environmental changes, microbes enter a lag phase during which cell growth is arrested, allowing cells to adapt to the new situation. The discovery of the lag phase started the field of gene regulation and led to the unraveling of underlying mechanisms. However, the factors determining the exact duration and dynamics of the lag phase remain largely elusive. Naively, one would expect that cells adapt as quickly as possible, so they can resume growth and compete with other organisms. However, recent studies show that the lag phase can last from several hours up to several days. Moreover, some cells within the same population take much longer than others, despite being genetically identical. In addition, the lag phase duration is also influenced by the past, with recent exposure to a given environment leading to a quicker adaptation when that environment returns. Genome-wide screens in Saccharomyces cerevisiae on carbon source shifts now suggest that the length of the lag phase, the heterogeneity in lag times of individual cells, and the history-dependent behavior are not determined by the time it takes to induce a few specific genes related to uptake and metabolism of a new carbon source. Instead, a major shift in general metabolism, and in particular a switch between fermentation and respiration, is the major bottleneck that determines lag duration. This suggests that there may be a fitness trade-off between complete adaptation of a cell’s metabolism to a given environment, and a short lag phase when the environment changes.
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Affiliation(s)
- Lieselotte Vermeersch
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium.,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium
| | - Gemma Perez-Samper
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium.,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium
| | - Bram Cerulus
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium.,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium
| | - Abbas Jariani
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium.,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium
| | - Brigida Gallone
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium.,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium.,Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 927, 9052, Ghent, Belgium.,VIB Center for Plant Systems Biology, Technologiepark 927, 9052, Ghent, Belgium
| | - Karin Voordeckers
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium.,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium
| | - Jan Steensels
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium.,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium
| | - Kevin J Verstrepen
- VIB Laboratory for Systems Biology, VIB-KU Leuven Center for Microbiology, Gaston Geenslaan 1, 3001, Leuven, Belgium. .,CMPG Laboratory of Genetics and Genomics, Department M2S, KU Leuven, Gaston Geenslaan 1, 3001, Leuven, Belgium.
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18
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Sagot I, Laporte D. Quiescence, an individual journey. Curr Genet 2019; 65:695-699. [PMID: 30649583 DOI: 10.1007/s00294-018-00928-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 12/21/2018] [Accepted: 12/24/2018] [Indexed: 12/14/2022]
Abstract
Quiescence is operationally characterized as a temporary and reversible proliferation arrest. There are many preconceived ideas about quiescence, quiescent cells being generally viewed as insignificant sleeping G1 cells. In fact, quiescence is central for organism physiology and its dysregulation involved in many pathologies. The quiescent state encompasses very diverse cellular situations depending on the cell type and its environment. This diversity challenges not only quiescence uniformity but also the universality of the molecular mechanisms beyond quiescence regulation. In this mini-perspective, we discuss recent advances in the concept of quiescence, and illustrate that this multifaceted cellular state is gaining increasing attention in many fields of biology.
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Affiliation(s)
- Isabelle Sagot
- Centre National de la Recherche Scientifique, Institut de Biochimie et Génétique Cellulaires, Unité Mixte de Recherche 5095, Université de Bordeaux, CS61390, Bordeaux Cedex, 33077, France.
| | - Damien Laporte
- Centre National de la Recherche Scientifique, Institut de Biochimie et Génétique Cellulaires, Unité Mixte de Recherche 5095, Université de Bordeaux, CS61390, Bordeaux Cedex, 33077, France
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19
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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.
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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
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20
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Abstract
Saccharomyces cerevisiae enter quiescence during extended growth in culture (greater than 7 days). Here, we describe a method to separate quiescent from non-quiescent cells by density gradient. We also describe approaches for DAPI staining the chromatin of quiescent cells, measuring quiescent cell viability, and extracting RNA from quiescent cells for use in genomics experiments.
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21
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Schultz LE, Haltom JA, Almeida MP, Wierson WA, Solin SL, Weiss TJ, Helmer JA, Sandquist EJ, Shive HR, McGrail M. Epigenetic regulators Rbbp4 and Hdac1 are overexpressed in a zebrafish model of RB1 embryonal brain tumor, and are required for neural progenitor survival and proliferation. Dis Model Mech 2018; 11:11/6/dmm034124. [PMID: 29914980 PMCID: PMC6031359 DOI: 10.1242/dmm.034124] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Accepted: 05/03/2018] [Indexed: 12/11/2022] Open
Abstract
In this study, we used comparative genomics and developmental genetics to identify epigenetic regulators driving oncogenesis in a zebrafish retinoblastoma 1 (rb1) somatic-targeting model of RB1 mutant embryonal brain tumors. Zebrafish rb1 brain tumors caused by TALEN or CRISPR targeting are histologically similar to human central nervous system primitive neuroectodermal tumors (CNS-PNETs). Like the human oligoneural OLIG2+/SOX10+ CNS-PNET subtype, zebrafish rb1 tumors show elevated expression of neural progenitor transcription factors olig2, sox10, sox8b and the receptor tyrosine kinase erbb3a oncogene. Comparison of rb1 tumor and rb1/rb1 germline mutant larval transcriptomes shows that the altered oligoneural precursor signature is specific to tumor tissue. More than 170 chromatin regulators were differentially expressed in rb1 tumors, including overexpression of chromatin remodeler components histone deacetylase 1 (hdac1) and retinoblastoma binding protein 4 (rbbp4). Germline mutant analysis confirms that zebrafish rb1, rbbp4 and hdac1 are required during brain development. rb1 is necessary for neural precursor cell cycle exit and terminal differentiation, rbbp4 is required for survival of postmitotic precursors, and hdac1 maintains proliferation of the neural stem cell/progenitor pool. We present an in vivo assay using somatic CRISPR targeting plus live imaging of histone-H2A.F/Z-GFP fusion protein in developing larval brain to rapidly test the role of chromatin remodelers in neural stem and progenitor cells. Our somatic assay recapitulates germline mutant phenotypes and reveals a dynamic view of their roles in neural cell populations. Our study provides new insight into the epigenetic processes that might drive pathogenesis in RB1 brain tumors, and identifies Rbbp4 and its associated chromatin remodeling complexes as potential target pathways to induce apoptosis in RB1 mutant brain cancer cells. This article has an associated First Person interview with the first author of the paper. Summary: This study shows that chromatin remodelers that are overexpressed in a zebrafish model of RB1 mutant brain cancer are required for neural progenitor proliferation and survival, providing insight into potential mechanisms that drive tumor growth.
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Affiliation(s)
- Laura E Schultz
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Jeffrey A Haltom
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Maira P Almeida
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Wesley A Wierson
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Staci L Solin
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Trevor J Weiss
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Jordan A Helmer
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Elizabeth J Sandquist
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
| | - Heather R Shive
- Department of Population Health and Pathobiology, North Carolina State University, Raleigh, NC 27607, USA
| | - Maura McGrail
- Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA
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22
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Zukowski A, Johnson AM. The interplay of histone H2B ubiquitination with budding and fission yeast heterochromatin. Curr Genet 2018; 64:799-806. [PMID: 29464330 DOI: 10.1007/s00294-018-0812-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 02/13/2018] [Accepted: 02/14/2018] [Indexed: 12/12/2022]
Abstract
Mono-ubiquitinated histone H2B (H2B-Ub) is important for chromatin regulation of transcription, chromatin assembly, and also influences heterochromatin. In this review, we discuss the effects of H2B-Ub from nucleosome to higher-order chromatin structure. We then assess what is currently known of the role of H2B-Ub in heterochromatic silencing in budding and fission yeasts (S. cerevisiae and S. pombe), which have distinct silencing mechanisms. In budding yeast, the SIR complex initiates heterochromatin assembly with the aid of a H2B-Ub deubiquitinase, Ubp10. In fission yeast, the RNAi-dependent pathway initiates heterochromatin in the context of low H2B-Ub. We examine how the different silencing machineries overcome the challenge of H2B-Ub chromatin and highlight the importance of using these microorganisms to further our understanding of H2B-Ub in heterochromatic silencing pathways.
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Affiliation(s)
- Alexis Zukowski
- Department of Biochemistry and Molecular Genetics, University of Colorado, Denver - School of Medicine, 12801 E. 17th Ave., Aurora, CO, 80045, USA
| | - Aaron M Johnson
- Department of Biochemistry and Molecular Genetics, University of Colorado, Denver - School of Medicine, 12801 E. 17th Ave., Aurora, CO, 80045, USA.
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23
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Stress response factors drive regrowth of quiescent cells. Curr Genet 2018; 64:807-810. [PMID: 29455333 DOI: 10.1007/s00294-018-0813-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 02/13/2018] [Accepted: 02/14/2018] [Indexed: 01/19/2023]
Abstract
Quiescent cells exploit an array of transcription factors to activate stress response machinery and maintain survival under nutrient-limited conditions. Our recent findings reveal that these transcription factors also play an important role in the exit of quiescence and regrowth. By studying Saccharomyces cerevisiae under a continuous, nutrient-limited condition, we found that Msn2 and Msn4 function as master regulators of glycolytic genes in the quiescent-like phase. They control the timing of transition from quiescence to growth by regulating the accumulation rate of acetyl-CoA, a key metabolite that is downstream of glycolysis and drives growth. These findings suggest a model that Msn2/4 not only protect the cells from starvation but also facilitate their regrowth from quiescence. Thus, understanding the functions of stress response transcription factors in metabolic regulation will provide deeper insight into how quiescent cells manage the capacity of regrowth.
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24
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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.
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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
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25
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Starvation signals in yeast are integrated to coordinate metabolic reprogramming and stress response to ensure longevity. Curr Genet 2017; 63:839-843. [PMID: 28444510 PMCID: PMC5605593 DOI: 10.1007/s00294-017-0697-4] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 04/14/2017] [Accepted: 04/20/2017] [Indexed: 11/02/2022]
Abstract
Studies on replicative and chronological aging in Saccharomyces cerevisiae have greatly advanced our understanding of how longevity is regulated in all eukaryotes. Chronological lifespan (CLS) of yeast is defined as the age-dependent viability of non-dividing cell populations. A number of nutrient sensing and signal transduction pathways (mainly TOR and PKA) have been shown to regulate CLS, yet it is poorly understood how the starvation signals transduced via these pathways lead to CLS extension. Using reporters whose expressions are induced by glucose starvation, we have screened the majority of the 'signaling' mutants in the yeast genome and identified many genes that are necessary for stress response. Subsequent analyses of the 'signaling' mutants not only revealed novel regulators of CLS, such as the GSK-3 ortholog Mck1, but also demonstrated that starvation signals transmitted by SNF1/AMPK, PKC1 and those negatively regulated by TOR/PKA, including Rim15, Yak1 and Mck1 kinases, are integrated to enable metabolic reprogramming and the acquisition of stress resistance. Coordinated metabolic reprogramming ensures the accumulation of storage carbohydrates for quiescent cells to maintain viability. We provide new evidence that Yak1, Rim15 and Mck1 kinases cooperate to activate H2O2-scanvenging activities, thus limiting the levels of ROS in cells entering quiescence. These findings support the recent advances in higher organisms that the flexibility of metabolic reprogramming and the balance between energetics and stress resistance are the unifying principles of lifespan extension. Future work to reveal how the metabolic switch and stress response is coordinated will help delineate the molecular mechanisms of aging in yeast and shed novel insight into aging/anti-aging principles in higher organisms.
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26
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Kelliher CM, Haase SB. Connecting virulence pathways to cell-cycle progression in the fungal pathogen Cryptococcus neoformans. Curr Genet 2017; 63:803-811. [PMID: 28265742 PMCID: PMC5605583 DOI: 10.1007/s00294-017-0688-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 02/22/2017] [Accepted: 02/22/2017] [Indexed: 11/01/2022]
Abstract
Proliferation and host evasion are critical processes to understand at a basic biological level for improving infectious disease treatment options. The human fungal pathogen Cryptococcus neoformans causes fungal meningitis in immunocompromised individuals by proliferating in cerebrospinal fluid. Current antifungal drugs target "virulence factors" for disease, such as components of the cell wall and polysaccharide capsule in C. neoformans. However, mechanistic links between virulence pathways and the cell cycle are not as well studied. Recently, cell-cycle synchronized C. neoformans cells were profiled over time to identify gene expression dynamics (Kelliher et al., PLoS Genet 12(12):e1006453, 2016). Almost 20% of all genes in the C. neoformans genome were periodically activated during the cell cycle in rich media, including 40 genes that have previously been implicated in virulence pathways. Here, we review important findings about cell-cycle-regulated genes in C. neoformans and provide two examples of virulence pathways-chitin synthesis and G-protein coupled receptor signaling-with their putative connections to cell division. We propose that a "comparative functional genomics" approach, leveraging gene expression timing during the cell cycle, orthology to genes in other fungal species, and previous experimental findings, can lead to mechanistic hypotheses connecting the cell cycle to fungal virulence.
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Affiliation(s)
- Christina M Kelliher
- Department of Biology, Duke University, Box 90338, 130 Science Drive, Durham, NC, 27708-0338, USA
| | - Steven B Haase
- Department of Biology, Duke University, Box 90338, 130 Science Drive, Durham, NC, 27708-0338, USA.
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