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Valverde JM, Dubra G, Phillips M, Haider A, Elena-Real C, Fournet A, Alghoul E, Chahar D, Andrés-Sanchez N, Paloni M, Bernadó P, van Mierlo G, Vermeulen M, van den Toorn H, Heck AJR, Constantinou A, Barducci A, Ghosh K, Sibille N, Knipscheer P, Krasinska L, Fisher D, Altelaar M. A cyclin-dependent kinase-mediated phosphorylation switch of disordered protein condensation. Nat Commun 2023; 14:6316. [PMID: 37813838 PMCID: PMC10562473 DOI: 10.1038/s41467-023-42049-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 09/28/2023] [Indexed: 10/11/2023] Open
Abstract
Cell cycle transitions result from global changes in protein phosphorylation states triggered by cyclin-dependent kinases (CDKs). To understand how this complexity produces an ordered and rapid cellular reorganisation, we generated a high-resolution map of changing phosphosites throughout unperturbed early cell cycles in single Xenopus embryos, derived the emergent principles through systems biology analysis, and tested them by biophysical modelling and biochemical experiments. We found that most dynamic phosphosites share two key characteristics: they occur on highly disordered proteins that localise to membraneless organelles, and are CDK targets. Furthermore, CDK-mediated multisite phosphorylation can switch homotypic interactions of such proteins between favourable and inhibitory modes for biomolecular condensate formation. These results provide insight into the molecular mechanisms and kinetics of mitotic cellular reorganisation.
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Affiliation(s)
- Juan Manuel Valverde
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Utrecht, 3584 CH, Utrecht, Netherlands
- Netherlands Proteomics Center, Padualaan 8, 3584 CH, Utrecht, Netherlands
| | - Geronimo Dubra
- IGMM, CNRS, University of Montpellier, INSERM, Montpellier, France
- Equipe Labellisée LIGUE 2018, Ligue Nationale Contre le Cancer, Paris, France
| | - Michael Phillips
- Department of Physics and Astronomy, University of Denver, Denver, Co, 80208, USA
| | - Austin Haider
- Department of Molecular and Cellular Biophysics, University of Denver, 80208, Denver, Co, USA
| | | | - Aurélie Fournet
- CBS, CNRS, University of Montpellier, INSERM, Montpellier, France
| | - Emile Alghoul
- IGH, CNRS, University of Montpellier, Montpellier, France
| | - Dhanvantri Chahar
- IGMM, CNRS, University of Montpellier, INSERM, Montpellier, France
- Equipe Labellisée LIGUE 2018, Ligue Nationale Contre le Cancer, Paris, France
| | - Nuria Andrés-Sanchez
- IGMM, CNRS, University of Montpellier, INSERM, Montpellier, France
- Equipe Labellisée LIGUE 2018, Ligue Nationale Contre le Cancer, Paris, France
| | - Matteo Paloni
- Department of Physics and Astronomy, University of Denver, Denver, Co, 80208, USA
| | - Pau Bernadó
- CBS, CNRS, University of Montpellier, INSERM, Montpellier, France
| | - Guido van Mierlo
- Department of Molecular Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences, Oncode Institute, Radboud University Nijmegen, Nijmegen, 6525 GA, The Netherlands
| | - Michiel Vermeulen
- Department of Molecular Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences, Oncode Institute, Radboud University Nijmegen, Nijmegen, 6525 GA, The Netherlands
| | - Henk van den Toorn
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Utrecht, 3584 CH, Utrecht, Netherlands
- Netherlands Proteomics Center, Padualaan 8, 3584 CH, Utrecht, Netherlands
| | - Albert J R Heck
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Utrecht, 3584 CH, Utrecht, Netherlands
- Netherlands Proteomics Center, Padualaan 8, 3584 CH, Utrecht, Netherlands
| | | | | | - Kingshuk Ghosh
- Department of Physics and Astronomy, University of Denver, Denver, Co, 80208, USA
- Department of Molecular and Cellular Biophysics, University of Denver, 80208, Denver, Co, USA
| | - Nathalie Sibille
- CBS, CNRS, University of Montpellier, INSERM, Montpellier, France
| | - Puck Knipscheer
- Oncode Institute, Hubrecht Institute-KNAW and University Medical Center, Utrecht, 3584 CT, Netherlands
| | - Liliana Krasinska
- IGMM, CNRS, University of Montpellier, INSERM, Montpellier, France
- Equipe Labellisée LIGUE 2018, Ligue Nationale Contre le Cancer, Paris, France
| | - Daniel Fisher
- IGMM, CNRS, University of Montpellier, INSERM, Montpellier, France.
- Equipe Labellisée LIGUE 2018, Ligue Nationale Contre le Cancer, Paris, France.
| | - Maarten Altelaar
- Biomolecular Mass Spectrometry and Proteomics, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, University of Utrecht, Utrecht, 3584 CH, Utrecht, Netherlands.
- Netherlands Proteomics Center, Padualaan 8, 3584 CH, Utrecht, Netherlands.
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Chen H, Good MC. Nascent transcriptome reveals orchestration of zygotic genome activation in early embryogenesis. Curr Biol 2022; 32:4314-4324.e7. [PMID: 36007528 PMCID: PMC9560990 DOI: 10.1016/j.cub.2022.07.078] [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: 02/01/2022] [Revised: 04/25/2022] [Accepted: 07/29/2022] [Indexed: 12/14/2022]
Abstract
Early embryo development requires maternal-to-zygotic transition, during which transcriptionally silent nuclei begin widespread gene expression during zygotic genome activation (ZGA).1-3 ZGA is vital for early cell fating and germ-layer specification,3,4 and ZGA timing is regulated by multiple mechanisms.1-5 However, controversies remain about whether these mechanisms are interrelated and vary among species6-10 and whether the timing of germ-layer-specific gene activation is temporally ordered.11,12 In some embryonic models, widespread ZGA onset is spatiotemporally graded,13,14 yet it is unclear whether the transcriptome follows this pattern. A major challenge in addressing these questions is to accurately measure the timing of each gene activation. Here, we metabolically label and identify the nascent transcriptome using 5-ethynyl uridine (5-EU) in Xenopus blastula embryos. We find that EU-RNA-seq outperforms total RNA-seq in detecting the ZGA transcriptome, which is dominated by transcription from maternal-zygotic genes, enabling improved ZGA timing determination. We uncover discrete spatiotemporal patterns for individual gene activation, a majority following a spatial pattern of ZGA that is correlated with a cell size gradient.14 We further reveal that transcription necessitates a period of developmental progression and that ZGA can be precociously induced by cycloheximide, potentially through elongation of interphase. Finally, most ectodermal genes are activated earlier than endodermal genes, suggesting a temporal orchestration of germ-layer-specific genes, potentially linked to the spatially graded pattern of ZGA. Together, our study provides fundamental new insights into the composition and dynamics of the ZGA transcriptome, mechanisms regulating ZGA timing, and its role in the onset of early cell fating.
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Affiliation(s)
- Hui Chen
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Matthew C Good
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Bioengineering, School of Engineering and Applied Science, University of Pennsylvania, Philadelphia, PA 19104, USA.
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3
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Swider ZT, Michaud A, Leda M, Landino J, Goryachev AB, Bement WM. Cell cycle and developmental control of cortical excitability in Xenopus laevis. Mol Biol Cell 2022; 33:ar73. [PMID: 35594176 PMCID: PMC9635278 DOI: 10.1091/mbc.e22-01-0025] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Interest in cortical excitability—the ability of the cell cortex to generate traveling waves of protein activity—has grown considerably over the past 20 years. Attributing biological functions to cortical excitability requires an understanding of the natural behavior of excitable waves and the ability to accurately quantify wave properties. Here we have investigated and quantified the onset of cortical excitability in Xenopus laevis eggs and embryos and the changes in cortical excitability throughout early development. We found that cortical excitability begins to manifest shortly after egg activation. Further, we identified a close relationship between wave properties—such as wave frequency and amplitude—and cell cycle progression as well as cell size. Finally, we identified quantitative differences between cortical excitability in the cleavage furrow relative to nonfurrow cortical excitability and showed that these wave regimes are mutually exclusive.
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Affiliation(s)
- Zachary T Swider
- Cellular and Molecular Biology Graduate Program, University of Wisconsin-Madison Madison, WI 53706.,Center for Quantitative Cell Imaging, University of Wisconsin-Madison Madison, WI 53706
| | - Ani Michaud
- Cellular and Molecular Biology Graduate Program, University of Wisconsin-Madison Madison, WI 53706.,Center for Quantitative Cell Imaging, University of Wisconsin-Madison Madison, WI 53706
| | - Marcin Leda
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Jennifer Landino
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan-Ann Arbor, Ann Arbor, MI 48109
| | - Andrew B Goryachev
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - William M Bement
- Cellular and Molecular Biology Graduate Program, University of Wisconsin-Madison Madison, WI 53706.,Center for Quantitative Cell Imaging, University of Wisconsin-Madison Madison, WI 53706.,Department of Integrative Biology, University of Wisconsin-Madison Madison, WI 53706
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Greenwood BL, Stuart DT. Synchronization of Saccharomyces cerevisiae Cells for Analysis of Progression Through the Cell Cycle. Methods Mol Biol 2022; 2579:145-168. [PMID: 36045205 DOI: 10.1007/978-1-0716-2736-5_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The cell division cycle is a fundamental process required for proliferation of all living organisms. The eukaryotic cell cycle follows a basic template with an ordered series of events beginning with G1 (Gap1) phase, followed successively by S (Synthesis) phase, G2 (Gap 2) phase, and M-phase (Mitosis). The process is tightly regulated in response to signals from both the internal and external milieu. The budding yeast S. cerevisiae is an outstanding model for the study of the cell cycle and its regulatory process. The basic events and regulatory processes of the S. cerevisiae cell cycle are highly conserved with other eukaryotes. The organism grows rapidly in simple medium, has a sequenced annotated genome, well-established genetics, and is amenable to analysis by proteomics and microscopy. Additionally, a range of tools and techniques are available to generate cultures of S. cerevisiae that are homogenously arrested or captured at specific phases of the cell cycle and upon release from that arrest these can be used to monitor cell cycle events as the cells synchronously proceed through a division cycle. In this chapter, we describe a series of commonly used techniques that are used to generate synchronized populations of S. cerevisiae and provide an overview of methods that can be used to monitor the progression of the cells through the cell division cycle.
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Affiliation(s)
| | - David T Stuart
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada.
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Aiba Y, Kim J, Imamura A, Okumoto K, Nakajo N. Regulation of Myt1 kinase activity via its N-terminal region in Xenopus meiosis and mitosis. Cells Dev 2021; 169:203754. [PMID: 34695617 DOI: 10.1016/j.cdev.2021.203754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 10/13/2021] [Accepted: 10/15/2021] [Indexed: 11/28/2022]
Abstract
Immature animal oocytes are naturally arrested at the first meiotic prophase (Pro-I), which corresponds to the G2 phase of the cell cycle. In Xenopus oocytes, Myt1 kinase phosphorylates and inactivates cyclin-dependent kinase 1 (Cdk1) at Pro-I, thereby preventing oocytes from entering meiosis I (MI) prematurely. Previous studies have shown that, upon resuming MI, Cdk1 and p90rsk, which is a downstream kinase of the Mos-MAPK pathway, in turn phosphorylate the C-terminal region of Myt1, to suppress its activity, thereby ensuring high Cdk1 activity during M phase. However, the roles of the N-terminal region of Myt1 during meiosis and mitosis remain to be elucidated. In the present study, we show that the N-terminal region of Myt1 participates in the regulation of Myt1 activity in the Xenopus cell cycle. In particular, we found that a short, conserved sequence in the N-terminal region, termed here as the PAYF motif, is required for the normal activity of Myt1 in oocytes. Furthermore, multiple phosphorylations by Cdk1 at the Myt1 N-terminal region were found to be involved in the negative regulation of Myt1. In particular, phosphorylations at Thr11 and Thr16 of Myt1, which are adjacent to the PAYF motif, were found to be important for the inactivation of Myt1 in the M phase of the cell cycle. These results suggest that in addition to the regulation of Myt1 activity via the C-terminal region, the N-terminal region of Myt1 also plays an important role in the regulation of Myt1 activity.
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Affiliation(s)
- Yukito Aiba
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan.
| | - Jihoon Kim
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan.
| | - Arata Imamura
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan.
| | - Kanji Okumoto
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan; Department of Biology, Graduate School of Sciences, Kyushu University, Fukuoka, Japan.
| | - Nobushige Nakajo
- Graduate School of Systems Life Sciences, Kyushu University, Fukuoka, Japan; Department of Biology, Graduate School of Sciences, Kyushu University, Fukuoka, Japan.
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Liu B, Zhao H, Wu K, Großhans J. Temporal Gradients Controlling Embryonic Cell Cycle. BIOLOGY 2021; 10:biology10060513. [PMID: 34207742 PMCID: PMC8228447 DOI: 10.3390/biology10060513] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 06/05/2021] [Accepted: 06/07/2021] [Indexed: 12/17/2022]
Abstract
Simple Summary Embryonic cells sense temporal gradients of regulatory signals to determine whether and when to proceed or remodel the cell cycle. Such a control mechanism is allowed to accurately link the cell cycle with the developmental program, including cell differentiation, morphogenesis, and gene expression. The mid-blastula transition has been a paradigm for timing in early embryogenesis in frog, fish, and fly, among others. It has been argued for decades now if the events associated with the mid-blastula transition, i.e., the onset of zygotic gene expression, remodeling of the cell cycle, and morphological changes, are determined by a control mechanism or by absolute time. Recent studies indicate that multiple independent signals and mechanisms contribute to the timing of these different processes. Here, we focus on the mechanisms for cell cycle remodeling, specifically in Drosophila, which relies on gradual changes of the signal over time. We discuss pathways for checkpoint activation, decay of Cdc25 protein levels, as well as depletion of deoxyribonucleotide metabolites and histone proteins. The gradual changes of these signals are linked to Cdk1 activity by readout mechanisms involving thresholds. Abstract Cell proliferation in early embryos by rapid cell cycles and its abrupt pause after a stereotypic number of divisions present an attractive system to study the timing mechanism in general and its coordination with developmental progression. In animals with large eggs, such as Xenopus, zebrafish, or Drosophila, 11–13 very fast and synchronous cycles are followed by a pause or slowdown of the cell cycle. The stage when the cell cycle is remodeled falls together with changes in cell behavior and activation of the zygotic genome and is often referred to as mid-blastula transition. The number of fast embryonic cell cycles represents a clear and binary readout of timing. Several factors controlling the cell cycle undergo dynamics and gradual changes in activity or concentration and thus may serve as temporal gradients. Recent studies have revealed that the gradual loss of Cdc25 protein, gradual depletion of free deoxyribonucleotide metabolites, or gradual depletion of free histone proteins impinge on Cdk1 activity in a threshold-like manner. In this review, we will highlight with a focus on Drosophila studies our current understanding and recent findings on the generation and readout of these temporal gradients, as well as their position within the regulatory network of the embryonic cell cycle.
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Affiliation(s)
- Boyang Liu
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan 250012, China; (B.L.); (H.Z.); (K.W.)
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Jinan 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan 250012, China
| | - Han Zhao
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan 250012, China; (B.L.); (H.Z.); (K.W.)
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Jinan 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan 250012, China
| | - Keliang Wu
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan 250012, China; (B.L.); (H.Z.); (K.W.)
- Key Laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan 250012, China
- Shandong Key Laboratory of Reproductive Medicine, Jinan 250012, China
- Shandong Provincial Clinical Research Center for Reproductive Health, Jinan 250012, China
- National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan 250012, China
| | - Jörg Großhans
- Department of Biology, Philipps University, 35043 Marburg, Germany
- Correspondence:
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Das P, Saha I, Chatterjee A, Pramanick K, Chakraborty S, Maity A, Bhowal S, Pradhan D, Mukherjee D, Maiti B. Participation of Phosphatidylinositol-3 Kinase Signalling in Human Chorionic Gonadotropin, Bovine Insulin (B-Insulin) and Human-Insulin-Like Growth Factor-I Induced Oocyte Maturation and Steroidogenesis in the Grey Mullet, Mugil Cephalus. ACTA ENDOCRINOLOGICA (BUCHAREST, ROMANIA : 2005) 2020; 16:426-436. [PMID: 34084233 PMCID: PMC8126398 DOI: 10.4183/aeb.2020.426] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
CONTEXT The grey mullet, Mugil cephalus, is an edible fish of high economic importance. Breeding biology with reference to hormonal/growth factor regulation of oocyte maturation needs to be known for its commercial production. OBJECTIVE The present study was conducted to examine the potency of maturation inducing hormones, chorionic gonadotropin (hCG), bovine-insulin, and insulin like growth factor1 (h-IGF-1) I on ovarian steroidogenesis and oocyte maturation. DESIGN The role of hormones and growth factors on steroidogenesis and oocyte maturation was investigated using specific inhibitors, Wortmannin for phosphatidylinositol-3 (PI3) kinase, trilostane for 3β-hydroxysteroid dehydrogenase, 1-octanol and 1-heptanol for gap junctions, actinomycin D for transcription and cycloheximide for translation of signal molecules. METHODS Actions of hormonal and growth factors were examined for steroidogenesis, by radioimmunoassay and oocyte maturation by germinal vesicle breakdown (GVBD). Specific inhibitors were used to determine the cell signaling pathways, PI3 kinase. RESULTS All the inhibitors attenuated the hCG-induced oocyte maturation (GVBD%), steroidogenesis including transcription, translation, gap junctions and PI3 kinase signaling. These inhibitors failed to inhibit h-IGF-I and b-insulin-induced oocyte maturation, steroidogenesis, translation and PI3 kinase signaling. CONCLUSION hCG induces oocyte maturation via steroid dependent pathway involving gap junctions, transcription, translation and PI3 kinase signaling, unlike h-IGF-I and b-insulin in the mullet.
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Affiliation(s)
- P. Das
- University Of Calcutta - Zoology, Kolkata, West Bengal, India
| | - I. Saha
- University Of Calcutta - Zoology, Kolkata, West Bengal, India
| | - A. Chatterjee
- University Of Calcutta - Zoology, Kolkata, West Bengal, India
| | - K. Pramanick
- University Of Calcutta - Zoology, Kolkata, West Bengal, India
| | | | - A. Maity
- University Of Calcutta - Zoology, Kolkata, West Bengal, India
| | - S. Bhowal
- University Of Calcutta - Biochemistry, Kolkata, West Bengal, India
| | - D. Pradhan
- Egra Sarada Shashi Bhusan College - Zoology, Egra, West Bengal, India
| | - D. Mukherjee
- University Of Calcutta - Zoology, Kolkata, West Bengal, India
| | - B.R. Maiti
- University Of Calcutta - Zoology, Kolkata, West Bengal, India
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8
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Padgett J, Santos SDM. From clocks to dominoes: lessons on cell cycle remodelling from embryonic stem cells. FEBS Lett 2020; 594:2031-2045. [PMID: 32535913 DOI: 10.1002/1873-3468.13862] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 05/01/2020] [Accepted: 05/27/2020] [Indexed: 12/21/2022]
Abstract
Cell division is a fundamental cellular process and the evolutionarily conserved networks that control cell division cycles adapt during development, tissue regeneration, cell de-differentiation and reprogramming, and a variety of pathological conditions. Embryonic development is a prime example of such versatility: fast, clock-like divisions hallmarking embryonic cells at early developmental stages become slower and controlled during cellular differentiation and lineage specification. In this review, we compare and contrast the unique cell cycle of mouse and human embryonic stem cells with that of early embryonic cells and of differentiated cells. We propose that embryonic stem cells provide an extraordinarily useful model system to understand cell cycle remodelling during embryonic-to-somatic transitions. We discuss how cell cycle networks help sustain embryonic stem cell pluripotency and self-renewal and how they safeguard cell identity and proper cell number in differentiated cells. Finally, we highlight the incredible diversity in cell cycle regulation within mammals and discuss the implications of studying cell cycle remodelling for understanding healthy and disease states.
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Affiliation(s)
- Joe Padgett
- Quantitative Cell Biology Lab, The Francis Crick Institute, London, UK
| | - Silvia D M Santos
- Quantitative Cell Biology Lab, The Francis Crick Institute, London, UK
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9
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Joshi YJ, Jawale YK, Athale CA. Modeling the tunability of the dual-feedback genetic oscillator. Phys Rev E 2020; 101:012417. [PMID: 32069648 DOI: 10.1103/physreve.101.012417] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Indexed: 11/07/2022]
Abstract
Oscillatory gene circuits are ubiquitous to biology and are involved in fundamental processes of cell cycle, circadian rhythms, and developmental systems. The synthesis of small, non-natural oscillatory genetic circuits has been increasingly used to test the fundamental principles of genetic network dynamics. While the "repressilator" was used to first demonstrate the proof of principle, a more recently developed dual-feedback, fast, tunable genetic oscillator has demonstrated a greater degree of robustness and control over oscillatory behavior by combining positive- and negative-feedback loops. This oscillator, combining lacI (negative-) and araC (positive-) feedback loops, was, however, modeled using multiple layers of differential equations to capture the molecular complexity of regulation, in order to explain the experimentally measured oscillations. In the search for design principles of such minimal oscillatory circuits, we have developed a reduced model of this dual-feedback loop oscillator consisting of just six differential equations, two of which are delay differential equations. The delay term is optimized, as the only free parameter, to fit the experimental dynamics of the oscillator period and amplitude tunability by the two inducers isopropyl β-D-1-thiogalactopyranoside (IPTG) and arabinose. We proceed to use our reduced and experimentally validated model to redesign the network by comparing the effect of asymmetry in gene expression at the level of (a) DNA copy numbers and the rates of (b) mRNA translation and (c) degradation, since experimental and theoretical work had predicted a need for an asymmetry in the copy numbers of activator (araC) and repressor (lacI) genes encoded on plasmids. We confirm that the minimal period of the oscillator is sensitive to DNA copy number asymmetry, and can demonstrate that while the asymmetry in the translation rate has an identical effect as the plasmid copy numbers, modulating the asymmetry in mRNA degradation can improve the tunability of the period and amplitude of the oscillator. Thus, our model predicts control at the level of translation can be used to redesign such networks, for improved tunability, while at the same time making the network robust to replication "noise" and the effects of the host cell cycle. Thus, our model predicts experimentally testable principles to redesign a potentially more robust oscillatory genetic network.
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Affiliation(s)
- Yash J Joshi
- Division of Biology, IISER Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
| | - Yash K Jawale
- Division of Biology, IISER Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
| | - Chaitanya A Athale
- Division of Biology, IISER Pune, Dr. Homi Bhabha Road, Pashan, Pune 411008, India
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Abstract
DNA replication starts with the opening of DNA at sites called DNA replication origins. From the single sequence-specific DNA replication origin of the small Escherichia coli genome, up to thousands of origins that are necessary to replicate the large human genome, strict sequence specificity has been lost. Nevertheless, genome-wide analyses performed in the recent years, using different mapping methods, demonstrated that there are precise locations along the metazoan genome from which replication initiates. These sites contain relaxed sequence consensus and epigenetic features. There is flexibility in the choice of origins to be used during a given cell cycle, probably imposed by evolution and developmental constraints. Here, we will briefly describe their main features.
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11
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Jevtić P, Mukherjee RN, Chen P, Levy DL. Altering the levels of nuclear import factors in early Xenopus laevis embryos affects later development. PLoS One 2019; 14:e0215740. [PMID: 31009515 PMCID: PMC6476522 DOI: 10.1371/journal.pone.0215740] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 04/08/2019] [Indexed: 11/19/2022] Open
Abstract
More than just a container for DNA, the nuclear envelope carries out a wide variety of critical and highly regulated cellular functions. One of these functions is nuclear import, and in this study we investigate how altering the levels of nuclear transport factors impacts developmental progression and organismal size. During early Xenopus laevis embryogenesis, the timing of a key developmental event, the midblastula transition (MBT), is sensitive to nuclear import factor levels. How might altering nuclear import factors and MBT timing in the early embryo affect downstream development of the organism? We microinjected X. laevis two-cell embryos with mRNA to increase levels of importin α or NTF2, resulting in differential amounts of nuclear import factors in the two halves of the embryo. Compared to controls, these embryos exhibited delayed gastrulation, curved neural plates, and bent tadpoles with different sized eyes. Furthermore, embryos microinjected with NTF2 developed into smaller froglets compared to control microinjected embryos. We propose that altering nuclear import factors and nuclear size affects MBT timing, cell size, and cell number, subsequently disrupting later development. Thus, altering nuclear import factors early in development can affect function and size at the organismal level.
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Affiliation(s)
- Predrag Jevtić
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, United States of America
| | - Richik N. Mukherjee
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, United States of America
| | - Pan Chen
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, United States of America
| | - Daniel L. Levy
- Department of Molecular Biology, University of Wyoming, Laramie, Wyoming, United States of America
- * E-mail:
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Lemmens B, Hegarat N, Akopyan K, Sala-Gaston J, Bartek J, Hochegger H, Lindqvist A. DNA Replication Determines Timing of Mitosis by Restricting CDK1 and PLK1 Activation. Mol Cell 2018; 71:117-128.e3. [PMID: 30008317 PMCID: PMC6039720 DOI: 10.1016/j.molcel.2018.05.026] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 04/27/2018] [Accepted: 05/21/2018] [Indexed: 12/26/2022]
Abstract
To maintain genome stability, cells need to replicate their DNA before dividing. Upon completion of bulk DNA synthesis, the mitotic kinases CDK1 and PLK1 become active and drive entry into mitosis. Here, we have tested the hypothesis that DNA replication determines the timing of mitotic kinase activation. Using an optimized double-degron system, together with kinase inhibitors to enforce tight inhibition of key proteins, we find that human cells unable to initiate DNA replication prematurely enter mitosis. Preventing DNA replication licensing and/or firing causes prompt activation of CDK1 and PLK1 in S phase. In the presence of DNA replication, inhibition of CHK1 and p38 leads to premature activation of mitotic kinases, which induces severe replication stress. Our results demonstrate that, rather than merely a cell cycle output, DNA replication is an integral signaling component that restricts activation of mitotic kinases. DNA replication thus functions as a brake that determines cell cycle duration.
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Affiliation(s)
- Bennie Lemmens
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden; Division of Genome Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet and Science for Life Laboratory, Stockholm, Sweden
| | - Nadia Hegarat
- Genome Damage and Stability Centre, University of Sussex, Brighton, UK
| | - Karen Akopyan
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Joan Sala-Gaston
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden
| | - Jiri Bartek
- Division of Genome Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet and Science for Life Laboratory, Stockholm, Sweden; Danish Cancer Society Research Center, Copenhagen, Denmark
| | - Helfrid Hochegger
- Genome Damage and Stability Centre, University of Sussex, Brighton, UK.
| | - Arne Lindqvist
- Department of Cell and Molecular Biology, Karolinska Institutet, Stockholm, Sweden.
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13
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Affiliation(s)
- Patrick L. Ferree
- Department of Cell Biology; Duke University Medical Center; Durham NC USA
| | - Stefano Di Talia
- Department of Cell Biology; Duke University Medical Center; Durham NC USA
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14
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Abstract
The activation of the zygotic genome and onset of transcription in blastula embryos is linked to changes in cell behavior and remodeling of the cell cycle and constitutes a transition from exclusive maternal to zygotic control of development. This step in development is referred to as mid-blastula transition and has served as a paradigm for the link between developmental program and cell behavior and morphology. Here, we discuss the mechanism and functional relationships between the zygotic genome activation and cell cycle control during mid-blastula transition with a focus on Drosophila embryos.
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Affiliation(s)
- Boyang Liu
- Institute for Developmental Biochemistry, Medical School, University of Göttingen, Justus-von-Liebig-Weg11, Göttingen 37077, Germany
| | - Jörg Grosshans
- Institute for Developmental Biochemistry, Medical School, University of Göttingen, Justus-von-Liebig-Weg11, Göttingen 37077, Germany.
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15
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Requirement for CCNB1 in mouse spermatogenesis. Cell Death Dis 2017; 8:e3142. [PMID: 29072697 PMCID: PMC5680922 DOI: 10.1038/cddis.2017.555] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Revised: 09/06/2017] [Accepted: 09/11/2017] [Indexed: 01/02/2023]
Abstract
Spermatogenesis, which involves mitosis and meiosis of male germ cells, is a highly complicated and coordinately ordered process. Cyclin B1 (CCNB1), an important regulator in cell cycle machinery, is proved essential for mouse embryonic development. However, the role of CCNB1 in mammalian spermatogenesis remains unclear. Here we tested the requirement for CCNB1 using conditional knockout mice lacking CCNB1 in male germ cells. We found that ablation of CCNB1 in gonocytes and spermatogonia led to mouse sterile caused by the male germ cells’ depletion. Gonocyte and spermatogonia without CCNB1 is unable to proliferate normally and apoptosis increased. Moreover, CCNB1 ablation in spermatogonia may promote their differentiation by downregulating Lin28a and upregulating let-7 miRNA. However, ablation of CCNB1 in premeiotic male germ cells did not have an effect on meiosis of spermatocytes and male fertility, suggesting that CCNB1 may be dispensable for meiosis of spermatocytes. Collectively, these results indicate that CCNB1 is critically required for the proliferation of gonocytes and spermatogonia but may be redundant in meiosis of spermatocytes in mouse spermatogenesis.
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16
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Both Nuclear Size and DNA Amount Contribute to Midblastula Transition Timing in Xenopus laevis. Sci Rep 2017; 7:7908. [PMID: 28801588 PMCID: PMC5554259 DOI: 10.1038/s41598-017-08243-z] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 07/10/2017] [Indexed: 11/08/2022] Open
Abstract
During early Xenopus laevis embryogenesis both nuclear and cell volumes decrease with the nuclear-to-cytoplasmic (N/C) volume ratio reaching a maximum at the midblastula transition (MBT). At the MBT, embryonic transcription is upregulated and cell cycles lengthen. Early studies demonstrated a role for the DNA-to-cytoplasmic ratio in the control of MBT timing. By altering nuclear size, we previously showed that the N/C volume ratio also contributes to proper MBT timing. Here we examine the relative contributions of nuclear size and DNA amount to MBT timing by simultaneously altering nuclear size and ploidy in X. laevis embryos. Compared to diploid embryos, haploids exhibited a delay in both zygotic gene expression and cell cycle lengthening, while diploid embryos with increased N/C volume ratios showed early expression of zygotic genes and premature lengthening of cell cycles. Interestingly, haploids with increased N/C volume ratios exhibited an intermediate effect on the timing of zygotic gene expression and cell cycle lengthening. Decreasing nuclear size in post-MBT haploid embryos caused a further delay in cell cycle lengthening and the expression of some zygotic genes. Our data suggest that both the N/C volume ratio and DNA amount contribute to the regulation of MBT timing with neither parameter being dominant.
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17
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Chikashige Y, Yamane M, Okamasa K, Osakada H, Tsutsumi C, Nagahama Y, Fukuta N, Haraguchi T, Hiraoka Y. Fission yeast APC/C activators Slp1 and Fzr1 sequentially trigger two consecutive nuclear divisions during meiosis. FEBS Lett 2017; 591:1029-1040. [PMID: 28245054 DOI: 10.1002/1873-3468.12612] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 02/22/2017] [Accepted: 02/24/2017] [Indexed: 01/05/2023]
Abstract
In meiosis, two rounds of nuclear division occur consecutively without DNA replication between the divisions. We isolated a fission yeast mutant in which the nucleus divides only once to generate two spores, as opposed to four, in meiosis. In this mutant, we found that the initiation codon of the slp1+ gene is converted to ATA, producing a reduced amount of Slp1. As a member of the Fizzy family of anaphase-promoting complex/cyclosome (APC/C) activators, Slp1 is essential for vegetative growth; however, the mutant allele shows a phenotype only in meiosis. Slp1 insufficiency delays degradation of maturation-promoting factor at the first meiotic division, and another APC/C activator, Fzr1, which acts late in meiosis, terminates meiosis immediately after the delayed first division to produce two viable spores.
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Affiliation(s)
- Yuji Chikashige
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Japan
| | - Miho Yamane
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Japan
| | - Kasumi Okamasa
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Japan
| | - Hiroko Osakada
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Japan
| | - Chihiro Tsutsumi
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Japan
| | - Yuki Nagahama
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Japan
| | - Noriko Fukuta
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Japan
| | - Tokuko Haraguchi
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Japan.,Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Yasushi Hiraoka
- Advanced ICT Research Institute Kobe, National Institute of Information and Communications Technology, Kobe, Japan.,Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
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18
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Zhang M, Skirkanich J, Lampson MA, Klein PS. Cell Cycle Remodeling and Zygotic Gene Activation at the Midblastula Transition. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 953:441-487. [DOI: 10.1007/978-3-319-46095-6_9] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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19
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Heim A, Rymarczyk B, Mayer TU. Regulation of Cell Division. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 953:83-116. [PMID: 27975271 DOI: 10.1007/978-3-319-46095-6_3] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The challenging task of mitotic cell divisions is to generate two genetically identical daughter cells from a single precursor cell. To accomplish this task, a complex regulatory network evolved, which ensures that all events critical for the duplication of cellular contents and their subsequent segregation occur in the correct order, at specific intervals and with the highest possible fidelity. Transitions between cell cycle stages are triggered by changes in the phosphorylation state and levels of components of the cell cycle machinery. Entry into S-phase and M-phase are mediated by cyclin-dependent kinases (Cdks), serine-threonine kinases that require a regulatory cyclin subunit for their activity. Resetting the system to the interphase state is mediated by protein phosphatases (PPs) that counteract Cdks by dephosphorylating their substrates. To avoid futile cycles of phosphorylation and dephosphorylation, Cdks and PPs must be regulated in a manner such that their activities are mutually exclusive.
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Affiliation(s)
- Andreas Heim
- Department of Biology and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstr. 10, 78457, Konstanz, Germany
| | - Beata Rymarczyk
- Department of Biology and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstr. 10, 78457, Konstanz, Germany
| | - Thomas U Mayer
- Department of Biology and Konstanz Research School Chemical Biology (KoRS-CB), University of Konstanz, Universitätsstr. 10, 78457, Konstanz, Germany.
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20
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Cavazza T, Peset I, Vernos I. From meiosis to mitosis - the sperm centrosome defines the kinetics of spindle assembly after fertilization in Xenopus. J Cell Sci 2016; 129:2538-47. [PMID: 27179073 DOI: 10.1242/jcs.183624] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 05/06/2016] [Indexed: 11/20/2022] Open
Abstract
Bipolar spindle assembly in the vertebrate oocyte relies on a self-organization chromosome-dependent pathway. Upon fertilization, the male gamete provides a centrosome, and the first and subsequent embryonic divisions occur in the presence of duplicated centrosomes that act as dominant microtubule organizing centres (MTOCs). The transition from meiosis to embryonic mitosis involves a necessary adaptation to integrate the dominant chromosome-dependent pathway with the centrosomes to form the bipolar spindle. Here, we took advantage of the Xenopus laevis egg extract system to mimic in vitro the assembly of the first embryonic spindle and investigate the respective contributions of the centrosome and the chromosome-dependent pathway to the kinetics of the spindle bipolarization. We found that centrosomes control the transition from the meiotic to the mitotic spindle assembly mechanism. By defining the kinetics of spindle bipolarization, the centrosomes ensure their own positioning to each spindle pole and thereby their essential correct inheritance to the two first daughter cells of the embryo for the development of a healthy organism.
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Affiliation(s)
- Tommaso Cavazza
- Cell and Developmental Biology Programme, Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Doctor Aiguader, 88 Barcelona 08003, Spain Universitat Pompeu Fabra (UPF), Doctor Aiguader 88, Barcelona 08003, Spain
| | - Isabel Peset
- Cell and Developmental Biology Programme, Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Doctor Aiguader, 88 Barcelona 08003, Spain Universitat Pompeu Fabra (UPF), Doctor Aiguader 88, Barcelona 08003, Spain
| | - Isabelle Vernos
- Cell and Developmental Biology Programme, Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Doctor Aiguader, 88 Barcelona 08003, Spain Universitat Pompeu Fabra (UPF), Doctor Aiguader 88, Barcelona 08003, Spain Institució Catalana de Recerca I Estudis Avançats (ICREA), Passeig de Lluis Companys 23, Barcelona 08010, Spain
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21
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Abstract
Sexual reproduction is essential for many organisms to propagate themselves. It requires the formation of haploid female and male gametes: oocytes and sperms. These specialized cells are generated through meiosis, a particular type of cell division that produces cells with recombined genomes that differ from their parental origin. In this review, we highlight the end process of female meiosis, the divisions per se, and how they can give rise to a functional female gamete preparing itself for the ensuing zygotic development. In particular, we discuss why such an essential process in the propagation of species is so poorly controlled, producing a strong percentage of abnormal female gametes in the end. Eventually, we examine aspects related to the lack of centrosomes in female oocytes, the asymmetry in size of the mammalian oocyte upon division, and in mammals the direct consequences of these long-lived cells in the ovary.
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22
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Abstract
Regulation of the cell-division cycle is fundamental for the growth, development, and reproduction of all species of life. In the past several decades, a conserved theme of cell cycle regulation has emerged from research in diverse model organisms. A comparison of distinct features of several diverse model organisms commonly used in cell cycle studies highlights their suitability for various experimental approaches, and recaptures their contributions to our current understanding of the eukaryotic cell cycle. A historic perspective presents a recollection of the breakthrough upon unfolding the universal principles of cell cycle control by scientists working with diverse model organisms, thereby appreciating the discovery pathways in this field. A comprehensive understanding is necessary to address current challenging questions about cell cycle control. Advances in genomics, proteomics, quantitative methodologies, and approaches of systems biology are redefining the traditional concept of what constitutes a model organism and have established a new era for development of novel, and refinement of the established model organisms. Researchers working in the field are no longer separated by their favorite model organisms; they have become more integrated into a larger community for gaining greater insights into how a cell divides and cycles. The new technologies provide a broad evolutionary spectrum of the cell-division cycle and allow informative comparisons among different species at a level that has never been possible, exerting unimaginable impact on our comprehensive understanding of cell cycle regulation.
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Affiliation(s)
- Zhaohua Tang
- W.M. Keck Science Center, The Claremont Colleges, 925 North Mills Avenue, Claremont, CA, 91711, USA,
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23
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Siefert JC, Clowdus EA, Sansam CL. Cell cycle control in the early embryonic development of aquatic animal species. Comp Biochem Physiol C Toxicol Pharmacol 2015; 178:8-15. [PMID: 26475527 PMCID: PMC4755307 DOI: 10.1016/j.cbpc.2015.10.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Revised: 10/07/2015] [Accepted: 10/09/2015] [Indexed: 01/02/2023]
Abstract
The cell cycle is integrated with many aspects of embryonic development. Not only is proper control over the pace of cell proliferation important, but also the timing of cell cycle progression is coordinated with transcription, cell migration, and cell differentiation. Due to the ease with which the embryos of aquatic organisms can be observed and manipulated, they have been a popular choice for embryologists throughout history. In the cell cycle field, aquatic organisms have been extremely important because they have played a major role in the discovery and analysis of key regulators of the cell cycle. In particular, the frog Xenopus laevis has been instrumental for understanding how the basic embryonic cell cycle is regulated. More recently, the zebrafish has been used to understand how the cell cycle is remodeled during vertebrate development and how it is regulated during morphogenesis. This review describes how some of the unique strengths of aquatic species have been leveraged for cell cycle research and suggests how species such as Xenopus and zebrafish will continue to reveal the roles of the cell cycle in human biology and disease.
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Affiliation(s)
- Joseph C Siefert
- Oklahoma Medical Research Foundation, Cell Cycle and Cancer Biology Research Program, Oklahoma City, OK, USA; University of Oklahoma Health Sciences Center, Department of Cell Biology, Oklahoma City, OK, USA
| | - Emily A Clowdus
- Oklahoma Medical Research Foundation, Cell Cycle and Cancer Biology Research Program, Oklahoma City, OK, USA; University of Oklahoma Health Sciences Center, Department of Cell Biology, Oklahoma City, OK, USA
| | - Christopher L Sansam
- Oklahoma Medical Research Foundation, Cell Cycle and Cancer Biology Research Program, Oklahoma City, OK, USA; University of Oklahoma Health Sciences Center, Department of Cell Biology, Oklahoma City, OK, USA.
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24
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Shinya M, Machiki D, Henrich T, Kubota Y, Takisawa H, Mimura S. Evolutionary diversification of MCM3 genes in Xenopus laevis and Danio rerio. Cell Cycle 2015; 13:3271-81. [PMID: 25485507 DOI: 10.4161/15384101.2014.954445] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Embryonic cell cycles of amphibians are rapid and lack zygotic transcription and checkpoint control. At the mid-blastula transition, zygotic transcription is initiated and cell divisions become asynchronous. Several cell cycle-related amphibian genes retain 2 distinct forms, maternal and zygotic, but little is known about the functional differences between these 2 forms of proteins. The minichromosome maintenance (MCM) 2-7 complex, consisting of 6 MCM proteins, plays a central role in the regulation of eukaryotic DNA replication. Almost all eukaryotes retain just a single MCM gene for each subunit. Here we report that Xenopus and zebrafish have 2 copies of MCM3 genes, one of which shows a maternal and the other a zygotic expression pattern. Phylogenetic analysis shows that the Xenopus and zebrafish zygotic MCM3 genes are more similar to their mammalian MCM3 ortholog, suggesting that maternal MCM3 was lost during evolution in most vertebrate lineages. Maternal MCM3 proteins in these 2 species are functionally different from zygotic MCM3 proteins because zygotic, but not maternal, MCM3 possesses an active nuclear localization signal in its C-terminal region, such as mammalian MCM3 orthologs do. mRNA injection experiments in zebrafish embryos show that overexpression of maternal MCM3 impairs proliferation and causes developmental defects, whereas zygotic MCM3 has a much weaker effect. This difference is brought about by the difference in their C-terminal regions, which contain putative nuclear localization signals; swapping the C-terminal region between maternal and zygotic genes diminishes the developmental defects. This study suggests that evolutionary diversification has occurred in MCM3 genes, leading to distinct functions, possibly as an adaption to the rapid DNA replication required for early development of Xenopus and zebrafish.
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Affiliation(s)
- Minori Shinya
- a Genetic Strains Research Center; National Institute of Genetics ; Mishima , Shizuoka , Japan
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25
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Positive mRNA Translational Control in Germ Cells by Initiation Factor Selectivity. BIOMED RESEARCH INTERNATIONAL 2015; 2015:327963. [PMID: 26357652 PMCID: PMC4556832 DOI: 10.1155/2015/327963] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 07/22/2015] [Indexed: 01/04/2023]
Abstract
Ultimately, the production of new proteins in undetermined cells pushes them to new fates. Other proteins hold a stem cell in a mode of self-renewal. In germ cells, these decision-making proteins are produced largely from translational control of preexisting mRNAs. To date, all of the regulation has been attributed to RNA binding proteins (RBPs) that repress mRNAs in many models of germ cell development (Drosophila, mouse, C. elegans, and Xenopus). In this review, we focus on the selective, positive function of translation initiation factors eIF4E and eIF4G, which recruit mRNAs to ribosomes upon derepression. Evidence now shows that the two events are not separate but rather are coordinated through composite complexes of repressors and germ cell isoforms of eIF4 factors. Strikingly, the initiation factor isoforms are themselves mRNA selective. The mRNP complexes of translation factors and RBPs are built on specific populations of mRNAs to prime them for subsequent translation initiation. Simple rearrangement of the partners causes a dormant mRNP to become synthetically active in germ cells when and where they are required to support gametogenesis.
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26
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Brandt YI, Mitchell T, Smolyakov GA, Osiński M, Hartley RS. Quantum dot assisted tracking of the intracellular protein Cyclin E in Xenopus laevis embryos. J Nanobiotechnology 2015; 13:31. [PMID: 25925383 PMCID: PMC4424550 DOI: 10.1186/s12951-015-0092-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Accepted: 04/20/2015] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Luminescent semiconductor nanocrystals, also known as quantum dots (QD), possess highly desirable optical properties that account for development of a variety of exciting biomedical techniques. These properties include long-term stability, brightness, narrow emission spectra, size tunable properties and resistance to photobleaching. QD have many promising applications in biology and the list is constantly growing. These applications include DNA or protein tagging for in vitro assays, deep-tissue imaging, fluorescence resonance energy transfer (FRET), and studying dynamics of cell surface receptors, among others. Here we explored the potential of QD-mediated labeling for the purpose of tracking an intracellular protein inside live cells. RESULTS We manufactured dihydrolipoic acid (DHLA)-capped CdSe-ZnS core-shell QD, not available commercially, and coupled them to the cell cycle regulatory protein Cyclin E. We then utilized the QD fluorescence capabilities for visualization of Cyclin E trafficking within cells of Xenopus laevis embryos in real time. CONCLUSIONS These studies provide "proof-of-concept" for this approach by tracking QD-tagged Cyclin E within cells of developing embryos, before and during an important developmental period, the midblastula transition. Importantly, we show that the attachment of QD to Cyclin E did not disrupt its proper intracellular distribution prior to and during the midblastula transition. The fate of the QD after cyclin E degradation following the midblastula transition remains unknown.
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Affiliation(s)
- Yekaterina I Brandt
- Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, 87131-0001, USA.
| | - Therese Mitchell
- Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, 87131-0001, USA.
| | - Gennady A Smolyakov
- Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico, 87106-4343, USA.
| | - Marek Osiński
- Center for High Technology Materials, University of New Mexico, 1313 Goddard SE, Albuquerque, New Mexico, 87106-4343, USA.
| | - Rebecca S Hartley
- Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico, 87131-0001, USA.
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27
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Broadus MR, Yew PR, Hann SR, Lee E. Small-molecule high-throughput screening utilizing Xenopus egg extract. Methods Mol Biol 2015; 1263:63-73. [PMID: 25618336 DOI: 10.1007/978-1-4939-2269-7_5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Screens for small-molecule modulators of biological pathways typically utilize cultured cell lines, purified proteins, or, recently, model organisms (e.g., zebrafish, Drosophila, C. elegans). Herein, we describe a method for using Xenopus laevis egg extract, a biologically active and highly tractable cell-free system that recapitulates a legion of complex chemical reactions found in intact cells. Specifically, we focus on the use of a luciferase-based fusion system to identify small-molecule modulators that affect protein turnover.
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Affiliation(s)
- Matthew R Broadus
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center, 465 21st Avenue South, U-4213A Learned Lab/MRBIII, Nashville, TN, 37232-8240, USA
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28
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Jevtić P, Levy DL. Nuclear size scaling during Xenopus early development contributes to midblastula transition timing. Curr Biol 2014; 25:45-52. [PMID: 25484296 DOI: 10.1016/j.cub.2014.10.051] [Citation(s) in RCA: 97] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 10/01/2014] [Accepted: 10/20/2014] [Indexed: 01/24/2023]
Abstract
Early Xenopus laevis embryogenesis is a robust system for investigating mechanisms of developmental timing. After a series of rapid cell divisions with concomitant reductions in cell size, the first major developmental transition is the midblastula transition (MBT), when zygotic transcription begins and cell cycles elongate. Whereas the maintenance of a constant nuclear-to-cytoplasmic (N/C) volume ratio is a conserved cellular property, it has long been recognized that the N/C volume ratio changes dramatically during early Xenopus development. We investigated how changes in nuclear size and the N/C volume ratio during early development contribute to the regulation of MBT timing. Whereas previous studies suggested a role for the N/C volume ratio in MBT timing, none directly tested the effects of altering nuclear size. In this study, we first quantify blastomere and nuclear sizes in X. laevis embryos, demonstrating that the N/C volume ratio increases prior to the MBT. We then manipulate nuclear volume in embryos by microinjecting different nuclear scaling factors, including import proteins, lamins, and reticulons. Using this approach, we show that increasing the N/C volume ratio in pre-MBT embryos leads to premature activation of zygotic gene transcription and early onset of longer cell cycles. Conversely, decreasing the N/C volume ratio delays zygotic transcription and leads to additional rapid cell divisions. Whereas the DNA-to-cytoplasmic ratio has been implicated in MBT timing, our data show that nuclear size also contributes to the regulation of MBT timing, demonstrating the functional significance of nuclear size during development.
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Affiliation(s)
- Predrag Jevtić
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA
| | - Daniel L Levy
- Department of Molecular Biology, University of Wyoming, Laramie, WY 82071, USA.
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29
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Stricker SA. Calcium signaling and endoplasmic reticulum dynamics during fertilization in marine protostome worms belonging to the phylum Nemertea. Biochem Biophys Res Commun 2014; 450:1182-7. [DOI: 10.1016/j.bbrc.2014.03.156] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 03/31/2014] [Indexed: 10/25/2022]
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30
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Chen TW, Broadus MR, Huppert SS, Lee E. Reconstitution Of β-catenin degradation in Xenopus egg extract. J Vis Exp 2014. [PMID: 24962160 DOI: 10.3791/51425] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Xenopus laevis egg extract is a well-characterized, robust system for studying the biochemistry of diverse cellular processes. Xenopus egg extract has been used to study protein turnover in many cellular contexts, including the cell cycle and signal transduction pathways(1-3). Herein, a method is described for isolating Xenopus egg extract that has been optimized to promote the degradation of the critical Wnt pathway component, β-catenin. Two different methods are described to assess β-catenin protein degradation in Xenopus egg extract. One method is visually informative ([(35)S]-radiolabeled proteins), while the other is more readily scaled for high-throughput assays (firefly luciferase-tagged fusion proteins). The techniques described can be used to, but are not limited to, assess β-catenin protein turnover and identify molecular components contributing to its turnover. Additionally, the ability to purify large volumes of homogenous Xenopus egg extract combined with the quantitative and facile readout of luciferase-tagged proteins allows this system to be easily adapted for high-throughput screening for modulators of β-catenin degradation.
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Affiliation(s)
- Tony W Chen
- Department of Cell and Developmental Biology and Program in Developmental Biology, Vanderbilt University Medical Center
| | - Matthew R Broadus
- Department of Cell and Developmental Biology and Program in Developmental Biology, Vanderbilt University Medical Center
| | - Stacey S Huppert
- Division of Gastroenterology, Hepatology & Nutrition and Division of Developmental Biology, Cincinnati Children's Hospital Medical Center
| | - Ethan Lee
- Department of Cell and Developmental Biology and Program in Developmental Biology, Vanderbilt University Medical Center; Vanderbilt Ingram Cancer Center, Vanderbilt University School of Medicine;
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Bišová K, Zachleder V. Cell-cycle regulation in green algae dividing by multiple fission. JOURNAL OF EXPERIMENTAL BOTANY 2014; 65:2585-602. [PMID: 24441762 DOI: 10.1093/jxb/ert466] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Green algae dividing by multiple fission comprise unrelated genera but are connected by one common feature: under optimal growth conditions, they can divide into more than two daughter cells. The number of daughter cells, also known as the division number, is relatively stable for most species and usually ranges from 4 to 16. The number of daughter cells is dictated by growth rate and is modulated by light and temperature. Green algae dividing by multiple fission can thus be used to study coordination of growth and progression of the cell cycle. Algal cultures can be synchronized naturally by alternating light/dark periods so that growth occurs in the light and DNA replication(s) and nuclear and cellular division(s) occur in the dark; synchrony in such cultures is almost 100% and can be maintained indefinitely. Moreover, the pattern of cell-cycle progression can be easily altered by differing growth conditions, allowing for detailed studies of coordination between individual cell-cycle events. Since the 1950s, green algae dividing by multiple fission have been studied as a unique model for cell-cycle regulation. Future sequencing of algal genomes will provide additional, high precision tools for physiological, taxonomic, structural, and molecular studies in these organisms.
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Affiliation(s)
- Kateřina Bišová
- Laboratory of Cell Cycles of Algae, Institute of Microbiology, Academy of Sciences of the Czech Republic, Opatovický mlýn, 379 81 Třeboň, Czech Republic
| | - Vilém Zachleder
- Laboratory of Cell Cycles of Algae, Institute of Microbiology, Academy of Sciences of the Czech Republic, Opatovický mlýn, 379 81 Třeboň, Czech Republic
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Das P, Pramanick K, Mukherjee D, Maiti BR. In vitro induction of oocyte maturation and steroidogenesis by gonadotropins, insulin, calcitonin and growth factor in an estuarine flat head grey mullet, Mugil cephalus L. FISH PHYSIOLOGY AND BIOCHEMISTRY 2014; 40:105-116. [PMID: 23925891 DOI: 10.1007/s10695-013-9828-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Accepted: 06/19/2013] [Indexed: 06/02/2023]
Abstract
In this article, an in vitro investigation was carried out to ascertain the roles of hormones and growth factor in the inductions of oocyte maturation and steroidogenesis of the postvitellogenic follicles in an Indian estuarine grey mullet, Mugil cephalus L. Oocyte maturation was evaluated by scoring the germinal vesicle breakdown (GVBD) percent of the postvitellogenic follicles. All the sex [17α,20β-dihydroxy-4-pregnane-3-one (DHP), estradiol 17β (E₂), progesterone (P), 17α-OH progesterone (17-OH-P) and testosterone] and other [bovine-insulin and salmon-calcitonin, human chorionic gonadotropin (hCG), luteinizing hormone (LH) or hCG+DHP] hormones and insulin-like growth factor-I (IGF-I) significantly increased GVBD% in 9 h culture. DHP had a maximum effect (75 %) compared to other effectors. Some effectors (hCG: 82.14 %, LH: 78.94 %, hCG plus DHP: 81.81 %, E₂: 80 % and IGF-I: 74.19 %) including DHP (79 %) further increased GVBD% in 15-h culture. All the hormones (except DHP) and IGF-I increased DHP, E₂ and testosterone productions by the postvitellogenic ovarian follicles in vitro. DHP and testosterone productions were increased with the increase of incubation time from 9 h through 15 h. E₂ production was not further increased beyond 12 h. DHP production was highest by hCG compared to other effectors. The hCG of all the test compounds was most effective in both the induction of GVBD% and steroid production. DHP is the most potent inducer of oocyte maturation in Indian estuarine flat head grey mullet. Involvement of estrogen in mullet oocyte maturation is indicated. hCG, like DHP, is equally potent and induces oocyte maturation via DHP production in vitro. hCG with DHP has synergistic action on oocyte maturation in mullet ovary. Interplay of several hormones (hCG, LH, and probably E₂ and testosterone) and IGF-I on oocyte maturation is suggested in the mullet.
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Affiliation(s)
- Puranjan Das
- Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Calcutta, 700019, India
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34
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Liu XJ. Polar body emission. Cytoskeleton (Hoboken) 2012; 69:670-85. [PMID: 22730245 DOI: 10.1002/cm.21041] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 05/15/2012] [Accepted: 05/21/2012] [Indexed: 12/13/2022]
Abstract
Generation of a haploid female germ cell, the egg, consists of two rounds of asymmetric cell division (meiosis I and meiosis II), yielding two diminutive and nonviable polar bodies and a large haploid egg. Animal eggs are also unique in the lack of centrioles and therefore form meiotic spindles without the pre-existence of the two dominant microtubule organizing centers (centrosomes) found in mitosis. Meiotic spindle assembly is further complicated by the unique requirement of sister chromatid mono-oriented in meiosis I. Nonetheless, the eggs appear to adopt many of the same proteins and mechanisms described in mitosis, with necessary modifications to accommodate their special needs. Unraveling these special modifications will not only help understanding animal reproduction, but should also enhance our understanding of cell division in general.
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Affiliation(s)
- X Johné Liu
- Chronic Disease Program, Ottawa Hospital Research Institute, Ottawa Hospital Civic Campus, 1053 Carling Avenue, Ottawa, K1Y 4E9, Canada.
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35
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Sen A, Prizant H, Hammes SR. Understanding extranuclear (nongenomic) androgen signaling: what a frog oocyte can tell us about human biology. Steroids 2011; 76:822-8. [PMID: 21354434 PMCID: PMC4972037 DOI: 10.1016/j.steroids.2011.02.016] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2010] [Revised: 01/13/2011] [Accepted: 02/16/2011] [Indexed: 12/13/2022]
Abstract
Steroids are key factors in a myriad of mammalian biological systems, including the brain, kidney, heart, bones, and gonads. While alternative potential steroid receptors have been described, the majority of biologically relevant steroid responses appear to be mediated by classical steroid receptors that are located in all parts of the cell, from the plasma membrane to the nucleus. Interestingly, these classical steroid receptors modulate different signals depending upon their location. For example, receptors in the plasma membrane interact with membrane signaling molecules, including G proteins and kinases. In contrast, receptors in the nucleus interact with nuclear signaling molecules, including transcriptional co-regulators. These extranuclear and intranuclear signals function together in an integrated fashion to regulate important biological functions. While most studies on extranuclear steroid signaling have focused on estrogens, recent work has demonstrated that nongenomic androgen signaling is equally important and that these two steroids modulate similar signaling pathways. In fact, by taking advantage of a simple model system whereby a physiologically relevant androgen-mediated process is regulated completely independent of transcription (Xenopus laevis oocyte maturation), many novel and conserved concepts in nongenomic steroid signaling have been uncovered and characterized.
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Affiliation(s)
| | | | - Stephen R Hammes
- Corresponding author: Stephen R Hammes, M.D., Ph.D., Division of Endocrinology and Metabolism, University of Rochester School of Medicine and Dentistry, 601 Elmwood Ave. Rochester, NY 14642. Phone: 585-275-2901; Fax: 585-273-1288;
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Lui JC, Nilsson O, Baron J. Growth plate senescence and catch-up growth. ENDOCRINE DEVELOPMENT 2011; 21:23-29. [PMID: 21865751 PMCID: PMC3420820 DOI: 10.1159/000328117] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Longitudinal bone growth is rapid in prenatal and early postnatal life, but then slows with age and eventually ceases. This growth deceleration is caused primarily by a decrease in chondrocyte proliferation, and is associated with other structural, functional, and molecular changes collectively termed growth plate senescence. Current evidence suggests that growth plate senescence occurs because the progenitor chondrocytes in the resting zone have a limited replicative capacity which is gradually exhausted with increasing cell division. In addition, recent experimental findings from laboratory and clinical studies suggest that growth plate senescence explains the phenomenon of catch-up growth. Growth-inhibiting conditions such as glucocorticoid excess and hypothyroidism delay the program of growth plate senescence. Consequently, growth plates are less senescent after these conditions resolve and therefore grow more rapidly than is normal for age, resulting in catch-up growth.
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Affiliation(s)
- Julian C. Lui
- Developmental Endocrinology Branch, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Md., USA
| | - Ola Nilsson
- Center for Molecular Medicine and Pediatric Endocrinology Unit Q2:08, Department of Women’s and Children’s Health, Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden
| | - Jeffrey Baron
- Developmental Endocrinology Branch, Program in Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Md., USA
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Iwamatsu T. Chromosome formation during fertilization in eggs of the teleost Oryzias latipes. Methods Mol Biol 2011; 761:97-124. [PMID: 21755444 DOI: 10.1007/978-1-61779-182-6_7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Upon fertilization, eggs shift their cell cycle from the meiotic to the mitotic pattern for embryogenesis. The information on chromosome formation has been accumulated by various experiments using inhibitors to affect formation and behavior of chromosomes in the cycle of cell proliferation. Based on experimental results on meiosis and early stages of development of the teleost Oryzias latipes, we discuss the roles of the activities of histone H1 kinase, microtubule-associated protein kinase, DNA polymerase, DNA topoisomerase, and other cytoplasmic factors that play a crucial role in formation and separation of chromosomes.
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Suprynowicz FA, Mazia D. Fluctuation of the Ca-sequestering activity of permeabilized sea urchin embryos during the cell cycle. Proc Natl Acad Sci U S A 2010; 82:2389-93. [PMID: 16593554 PMCID: PMC397563 DOI: 10.1073/pnas.82.8.2389] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
We have followed the sequestration of Ca(2+) by intracellular compartments in sea urchin embryos through the first cell cycles. To gain biochemical access to these compartments, the embryos were permeabilized by brief exposure to an intense electric field. Sequestration was determined as the retention of tracer, (45)Ca, after filtration of aliquots on Millipore filters. The permeabilized cells sequester Ca(2+) at a constant rate for at least 20 min, with the following characteristics: (i) ATP is required. (ii) Sequestration occurs at Ca(2+) levels corresponding to those estimated in vivo. (iii) The Ca(2+) concentration dependence of sequestration and its insensitivity to mitochondrial poisons imply that the activity derives from a single, nonmitochondrial transport system. The Ca(2+)-sequestering activities of embryos that are permeabiized at successive stages of the first cell cycle (one-cell stage) progressively increase to 5 times the initial level. The rate of sequestration is maximal during telophase and, in some populations of zygotes, is nearly as great throughout prophase. Over the course of the second cell cycle (two-cell stage), the activity undergoes a 2-fold oscillation that bears the same temporal relationship to mitosis as the previous fluctuation.
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Affiliation(s)
- F A Suprynowicz
- Department of Biological Sciences, Stanford University, Hopkins Marine Station, Pacific Grove, CA 93950
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39
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Guerrier P, Neant I. Metabolic cooperation following fusion of starfish ootid and primary oocyte restores meiotic-phase-promoting activity. Proc Natl Acad Sci U S A 2010; 83:4814-8. [PMID: 16593719 PMCID: PMC323832 DOI: 10.1073/pnas.83.13.4814] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
In the starfish Marthasterias glacialis, polyethylene glycol (PEG) homologous fused pairs consisting of two immature oocytes, blocked at the germinal vesicle stage, or two ootids, blocked at the female pronucleus stage, remain arrested at these specific stages, unless they are stimulated by the hormone 1-methyladenine. In contrast, heterologous pairs develop up to female pronucleus formation in the immature partner, indicating that maturation-promoting factor was formed under these conditions. Kinetics for this process, reconstitution of the nuclear envelopes after first polar body extrusion, and delaying effect of emetine argue for the existence of a true metabolic cooperation process requiring complementary factors present in each partner. The effect of inhibitors that penetrate the plasma membrane points to the possible involvement of endogenous proteases that may activate latent or neosynthesized maturation-promoting factor precursor and/or protein kinases.
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Affiliation(s)
- P Guerrier
- Developmental Biology, LP 4601 Centre National de la Recherche Scientifique, Station Biologique, Roscoff, 29211, France
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Meiosis requires a translational positive loop where CPEB1 ensues its replacement by CPEB4. EMBO J 2010; 29:2182-93. [PMID: 20531391 DOI: 10.1038/emboj.2010.111] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2010] [Accepted: 05/10/2010] [Indexed: 11/08/2022] Open
Abstract
Meiotic progression is driven by the sequential translational activation of maternal messenger RNAs stored in the cytoplasm. This activation is mainly induced by the cytoplasmic elongation of their poly(A) tails, which is mediated by the cytoplasmic polyadenylation element (CPE) present in their 3' untranslated regions. Although polyadenylation in prophase I and metaphase I is mediated by the CPE-binding protein 1 (CPEB1), this protein is degraded during the first meiotic division. Thus, raising the question of how the cytoplasmic polyadenylation required for the second meiotic division is achieved. In this work, we show that CPEB1 generates a positive loop by activating the translation of CPEB4 mRNA, which, in turn, replaces CPEB1 and drives the transition from metaphase I to metaphase II. We further show that CPEB1 and CPEB4 are differentially regulated by phase-specific kinases, generating the need of two sequential CPEB activities to sustain cytoplasmic polyadenylation during all the meiotic phases. Altogether, this work defines a new element in the translational circuit that support an autonomous transition between the two meiotic divisions in the absence of DNA replication.
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41
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Nakamura A, Naito M, Arai H, Fujita N. Mitotic phosphorylation of Aki1 at Ser208 by cyclin B1-Cdk1 complex. Biochem Biophys Res Commun 2010; 393:872-6. [PMID: 20171170 DOI: 10.1016/j.bbrc.2010.02.103] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 02/16/2010] [Indexed: 12/23/2022]
Abstract
Akt kinase-interacting protein 1 (Aki1)/Freud-1/CC2D1A is localized in the cytosol, nucleus, and centrosome. Aki1 plays distinct roles depending on its localization. In the cytosol, it acts as a scaffold protein in the phosphoinositide 3-kinase (PI3K)/3-phosphoinositide-dependent protein kinase 1 (PDK1)/Akt pathway. In the nucleus, it is a transcriptional repressor of the serotonin-1A (5-HT1A) receptor. In the centrosome, it regulates spindle pole localization of the cohesin subunit Scc1, thereby mediating centriole cohesion during mitosis. Although the function of Aki1 has been well clarified, the regulatory machinery of Aki1 is poorly understood. We previously found that Aki1 in mitotic cells displayed reduced mobility on immunoblot analysis, but the reason for this was unclear. Here we show that the electrophoretic mobility shift of Aki1 is derived from mitotic phosphorylation. The cyclin B1-cyclin-dependent kinase 1 (Cdk1) complex was found to be one of the kinases responsible for Aki1 phosphorylation during mitosis. We identified the Ser(208) residue of Aki1 as a cyclin B1-Cdk1 phosphorylation site. Furthermore, cyclin B1-Cdk1 inhibitor treatment was shown to attenuate the level of Aki1 in complex with Scc1, suggesting that Aki1 phosphorylation by cyclin B1-Cdk1 contributes to Aki1-Scc1 complex formation. Our results indicate that cyclin B1-Cdk1 is a kinase of Aki1 during mitosis and that its phosphorylation of Aki1 may regulate mitotic function.
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Affiliation(s)
- Akito Nakamura
- Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Tokyo 135-8550, Japan
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Hwang YS, Luo T, Xu Y, Sargent TD. Myosin-X is required for cranial neural crest cell migration in Xenopus laevis. Dev Dyn 2010; 238:2522-9. [PMID: 19718754 DOI: 10.1002/dvdy.22077] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Myosin-X (MyoX) belongs to a large family of unconventional, nonmuscle, actin-dependent motor proteins. We show that MyoX is predominantly expressed in cranial neural crest (CNC) cells in embryos of Xenopus laevis and is required for head and jaw cartilage development. Knockdown of MyoX expression using antisense morpholino oligonucleotides resulted in retarded migration of CNC cells into the pharyngeal arches, leading to subsequent hypoplasia of cartilage and inhibited outgrowth of the CNC-derived trigeminal nerve. In vitro migration assays on fibronectin using explanted CNC cells showed significant inhibition of filopodia formation, cell attachment, spreading and migration, accompanied by disruption of the actin cytoskeleton. These data support the conclusion that MyoX has an essential function in CNC migration in the vertebrate embryo.
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Affiliation(s)
- Yoo-Seok Hwang
- Laboratory of Molecular Genetics, NICHD, NIH, Bethesda, Maryland 20892, USA
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Hulstrand AM, Schneider PN, Houston DW. The use of antisense oligonucleotides in Xenopus oocytes. Methods 2010; 51:75-81. [PMID: 20045732 DOI: 10.1016/j.ymeth.2009.12.015] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2009] [Accepted: 12/30/2009] [Indexed: 11/18/2022] Open
Abstract
The ability to manipulate gene expression in Xenopus oocytes and then generate fertilized embryos by transfer into host females has made it possible to rapidly characterize maternal signaling pathways in vertebrate development. Maternal mRNAs in particular can be efficiently depleted using antisense deoxyoligonucleotides (oligos), mediated by endogenous RNase-H activity. Since the microinjection of antisense reagents or mRNAs into eggs after fertilization often fails to affect maternal signaling pathways, mRNA depletion in the Xenopus oocyte is uniquely suited to assessing maternal functions. In this review, we highlight the advantages of using antisense in Xenopus oocytes and describe basic methods for designing and choosing effective oligos. We also summarize the procedures for fertilizing cultured oocytes by host-transfer and interpreting the specificity of antisense effects. Although these methods can be technically demanding, the use of antisense in oocytes can be used to address biological questions that are intractable in other experimental settings.
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Affiliation(s)
- Alissa M Hulstrand
- The University of Iowa, Department of Biology, 257 BB, Iowa City, IA 52242-1324, USA
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Wickliffe K, Williamson A, Jin L, Rape M. The multiple layers of ubiquitin-dependent cell cycle control. Chem Rev 2009; 109:1537-48. [PMID: 19146381 PMCID: PMC3206288 DOI: 10.1021/cr800414e] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Katherine Wickliffe
- University of California at Berkeley, Department of Molecular and Cell Biology, Berkeley, CA 94720, USA
| | - Adam Williamson
- University of California at Berkeley, Department of Molecular and Cell Biology, Berkeley, CA 94720, USA
| | - Lingyan Jin
- University of California at Berkeley, Department of Molecular and Cell Biology, Berkeley, CA 94720, USA
| | - Michael Rape
- University of California at Berkeley, Department of Molecular and Cell Biology, Berkeley, CA 94720, USA
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Abstract
Embryonic stem cells have the capacity for unlimited proliferation while retaining their potential to differentiate into a wide variety of cell types. Murine, primate and human embryonic stem cells (ESCs) exhibit a very unusual cell cycle structure, characterized by a short G1 phase and a high proportion of cells in S-phase. In the case of mESCs, this is associated with a unique mechanism of cell cycle regulation, underpinned by the precocious activity of cyclin dependent protein kinase (Cdk) activities. As ES cells differentiate, their cell cycle structure changes dramatically so as to incorporate a significantly longer G1 phase and their mechanism of cell cycle regulation changes to that typically seen in other mammalian cells. The unique cell cycle structure and mechanism of cell cycle control indicates that the cell cycle machinery plays a role in establishment or maintenance of the stem cell state. This idea is supported by the frequent involvement of cell cycle regulatory molecules in cell immortalization.
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Affiliation(s)
- Josephine White
- Department of Molecular Biosciences, University of Adelaide, South Australia, 5005
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Sedgwick C, Rawluk M, Decesare J, Raithatha S, Wohlschlegel J, Semchuk P, Ellison M, Yates J, Stuart D. Saccharomyces cerevisiae Ime2 phosphorylates Sic1 at multiple PXS/T sites but is insufficient to trigger Sic1 degradation. Biochem J 2006; 399:151-60. [PMID: 16776651 PMCID: PMC1570159 DOI: 10.1042/bj20060363] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The initiation of DNA replication in Saccharomyces cerevisiae depends upon the destruction of the Clb-Cdc28 inhibitor Sic1. In proliferating cells Cln-Cdc28 complexes phosphorylate Sic1, which stimulates binding of Sic1 to SCF(Cdc4) and triggers its proteosome mediated destruction. During sporulation cyclins are not expressed, yet Sic1 is still destroyed at the G1-/S-phase boundary. The Cdk (cyclin dependent kinase) sites are also required for Sic1 destruction during sporulation. Sic1 that is devoid of Cdk phosphorylation sites displays increased stability and decreased phosphorylation in vivo. In addition, we found that Sic1 was modified by ubiquitin in sporulating cells and that SCF(Cdc4) was required for this modification. The meiosis-specific kinase Ime2 has been proposed to promote Sic1 destruction by phosphorylating Sic1 in sporulating cells. We found that Ime2 phosphorylates Sic1 at multiple sites in vitro. However, only a subset of these sites corresponds to Cdk sites. The identification of multiple sites phosphorylated by Ime2 has allowed us to propose a motif for phosphorylation by Ime2 (PXS/T) where serine or threonine acts as a phospho-acceptor. Although Ime2 phosphorylates Sic1 at multiple sites in vitro, the modified Sic1 fails to bind to SCF(Cdc4). In addition, the expression of Ime2 in G1 arrested haploid cells does not promote the destruction of Sic1. These data support a model where Ime2 is necessary but not sufficient to promote Sic1 destruction during sporulation.
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Affiliation(s)
- Chantelle Sedgwick
- *Department of Biochemistry, 561 Medical Sciences Building, University of Alberta, Edmonton, AB, T6G 2H7, Canada
| | - Matthew Rawluk
- *Department of Biochemistry, 561 Medical Sciences Building, University of Alberta, Edmonton, AB, T6G 2H7, Canada
| | - James Decesare
- *Department of Biochemistry, 561 Medical Sciences Building, University of Alberta, Edmonton, AB, T6G 2H7, Canada
| | - Sheetal Raithatha
- *Department of Biochemistry, 561 Medical Sciences Building, University of Alberta, Edmonton, AB, T6G 2H7, Canada
| | - James Wohlschlegel
- †The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037 U.S.A
| | - Paul Semchuk
- ‡Institute for Biomolecular Design, 367 Medical Sciences Building, University of Alberta, Edmonton AB, T6G 2H7, Canada
| | - Michael Ellison
- ‡Institute for Biomolecular Design, 367 Medical Sciences Building, University of Alberta, Edmonton AB, T6G 2H7, Canada
| | - John Yates
- †The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92037 U.S.A
| | - David Stuart
- *Department of Biochemistry, 561 Medical Sciences Building, University of Alberta, Edmonton, AB, T6G 2H7, Canada
- To whom correspondence should be addressed (email )
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Zammataro L, Serini G, Rowland T, Bussolino F. Embryonic cleavage modeling as a computational approach to sphere packing problem. J Theor Biol 2006; 245:77-82. [PMID: 17087975 DOI: 10.1016/j.jtbi.2006.09.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2006] [Revised: 09/27/2006] [Accepted: 09/28/2006] [Indexed: 10/24/2022]
Abstract
Embryonic cleavage depends on the distribution in the cytosol of molecular signals that influence mitotic spindle positioning. By implementing the New Kind of Science (NKS) theory in which a simple rule can evolve with a complex overall behavior, here we propose a new theoretical approach that is capable of modeling the mechanisms of early embryonic cleavage dynamics in the ascidian Styela Partita. The model shows that the same spindle pole orientation rule governs the first five embryonic cleavages, which progressively allow the transition from one to thirty-two daughter cells. Finally, we present evidence of a strong similarity between Kepler's Sphere Packing Problem and embryonic cleavage, which thus represents a prominent example of natural computing.
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Affiliation(s)
- Luca Zammataro
- Department of Oncological Sciences and Division of Molecular Angiogenesis, Institute for Cancer Research and Treatment, University of Torino School of Medicine, 10060 Candiolo, Italy.
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Harkness TAA. Decondensation of Xenopus sperm chromatin using Saccharomyces cerevisiae whole-cell extracts. Can J Physiol Pharmacol 2006; 84:451-8. [PMID: 16902590 DOI: 10.1139/y05-042] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Biochemical studies using highly condensed Xenopus sperm chromatin and protein extracts prepared from multiple systems have lead to the identification of conserved proteins involved in chromosome decondensation. However, mutations to these proteins are unavailable as the systems used are not amenable to genetic studies. We took a genetic approach to isolating chromosome decondensation mutants by incubating Xenopus sperm chromatin with whole-cell extracts prepared from the Hartwell library of random temperature sensitive (ts) yeast cells. We show that decondensation of Xenopus sperm chromatin using wild type yeast extracts was rapid, ATP- and extract-dependent, and resistant to heat, N-ethylmaleimide, protease K, RNase A, and micrococcal nuclease. From 100 mutant extracts screened, we obtained one strain, referred to as rmc4, that was chromosome decondensation defective. The mutant was slow growing and exhibited germination defects. Low concentrations of rmc4 extract would eventually decondense sperm heads, and fractionation of the mutant extract produced a decondensation competent fraction, suggesting the presence of an overactive inhibitor in rmc4 cells. We performed a multicopy suppressor screen that identified PDE2, a gene encoding a protein that inhibits protein kinase A (PKA) activity. As PKA was previously shown in human cells to maintain condensed chromatin, our results suggest that PKA activity is elevated in rmc4 cells, causing a decondensation defect. Thus, our experiments reveal that yeast encodes an evolutionarily conserved chromosome decondensation activity that can be genetically manipulated.
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Affiliation(s)
- Troy A A Harkness
- Department of Anatomy and Cell Biology, College of Medicine, University of Saskatchewan, B313 Health Sciences Building, Saskatoon, Canada.
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Gutierrez GJ, Vögtlin A, Castro A, Ferby I, Salvagiotto G, Ronai Z, Lorca T, Nebreda AR. Meiotic regulation of the CDK activator RINGO/Speedy by ubiquitin-proteasome-mediated processing and degradation. Nat Cell Biol 2006; 8:1084-94. [PMID: 16964245 DOI: 10.1038/ncb1472] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2006] [Accepted: 08/10/2006] [Indexed: 01/17/2023]
Abstract
Xenopus RINGO/Speedy (XRINGO) is a potent inducer of oocyte meiotic maturation that can directly activate Cdk1 and Cdk2. Here, we show that endogenous XRINGO protein accumulates transiently during meiosis I entry and then is downregulated. This tight regulation of XRINGO expression is the consequence of two interconnected mechanisms: processing and degradation. XRINGO processing involves recognition of at least three distinct phosphorylated recognition motifs by the SCF(betaTrCP) ubiquitin ligase, followed by proteasome-mediated limited degradation, resulting in an amino-terminal XRINGO fragment. XRINGO processing is directly stimulated by several kinases, including protein kinase A and glycogen synthase kinase-3beta, and may contribute to the maintenance of G2 arrest. On the other hand, XRINGO degradation after meiosis I is mediated by the ubiquitin ligase Siah-2, which probably requires phosphorylation of XRINGO on Ser 243 and may be important for the omission of S phase at the meiosis-I-meiosis-II transition in Xenopus oocytes.
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Bean JM, Siggia ED, Cross FR. Coherence and Timing of Cell Cycle Start Examined at Single-Cell Resolution. Mol Cell 2006; 21:3-14. [PMID: 16387649 DOI: 10.1016/j.molcel.2005.10.035] [Citation(s) in RCA: 113] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2005] [Revised: 09/22/2005] [Accepted: 10/28/2005] [Indexed: 11/17/2022]
Abstract
Cell cycle "Start" in budding yeast involves induction of a large battery of G1/S-regulated genes, coordinated with bud morphogenesis. It is unknown how intra-Start coherence of these events and inter-Start timing regularity are achieved. We developed quantitative time-lapse fluorescence microscopy on a multicell-cycle timescale, for following expression of unstable GFP under control of the G1 cyclin CLN2 promoter. Swi4, a major activator of the G1/S regulon, was required for a robustly coherent Start, as swi4 cells exhibited highly variable loss of cooccurrence of regular levels of CLN2pr-GFP expression with budding. In contrast, other known Start regulators Mbp1 and Cln3 are not needed for coherence but ensure regular timing of Start onset. The interval of nuclear retention of Whi5, a Swi4 repressor, largely accounts for wild-type mother-daughter asymmetry and for variable Start timing in cln3 mbp1 cells. Thus, multiple pathways may independently suppress qualitatively different kinds of noise at Start.
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Affiliation(s)
- James M Bean
- The Rockefeller University, New York, New York 10021, USA
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