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Puls O, Ruiz-Reynés D, Tavella F, Jin M, Kim Y, Gelens L, Yang Q. Mitotic waves in frog egg extracts: Transition from phase waves to trigger waves. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.18.576267. [PMID: 38496576 PMCID: PMC10942321 DOI: 10.1101/2024.01.18.576267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Cyclin-dependent kinase 1 (Cdk1) activity rises and falls throughout the cell cycle, a cell-autonomous process known as mitotic oscillations. These oscillators can synchronize when spatially coupled, providing a crucial foundation for rapid synchronous divisions in large early embryos like Drosophila (~ 0.5 mm) and Xenopus (~ 1.2 mm). While diffusion alone cannot achieve such long-range coordination, recent studies have proposed two types of mitotic waves, phase and trigger waves, to explain the phenomena. How the waves establish over time for efficient spatial coordination remains unclear. Using Xenopus laevis egg extracts and a Cdk1 FRET sensor, we observe a transition from phase waves to a trigger wave regime in an initially homogeneous cytosol. Adding nuclei accelerates such transition. Moreover, the system transitions almost immediately to this regime when externally driven by metaphase-arrested extracts from the boundary. Employing computational modeling, we pinpoint how wave nature, including speed-period relation, depends on transient dynamics and oscillator properties, suggesting that phase waves appear transiently due to the time required for trigger waves to entrain the system and that spatial heterogeneity promotes entrainment. Therefore, we show that both waves belong to a single biological process capable of coordinating the cell cycle over long distances.
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Affiliation(s)
- Owen Puls
- Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Daniel Ruiz-Reynés
- Laboratory of Dynamics in Biological Systems, KU Leuven, Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
- IFISC (CSIC-UIB). Instituto de Física Interdisciplinar y Sistemas Complejos, E-07122 Palma de Mallorca, Spain
| | - Franco Tavella
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Minjun Jin
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Yeonghoon Kim
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
| | - Lendert Gelens
- Laboratory of Dynamics in Biological Systems, KU Leuven, Department of Cellular and Molecular Medicine, University of Leuven, B-3000 Leuven, Belgium
| | - Qiong Yang
- Department of Physics, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biophysics, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA
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Wong SS, Wainman A, Saurya S, Raff JW. Regulation of centrosome size by the cell-cycle oscillator in Drosophila embryos. EMBO J 2024; 43:414-436. [PMID: 38233576 PMCID: PMC10898259 DOI: 10.1038/s44318-023-00022-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 12/12/2023] [Accepted: 12/13/2023] [Indexed: 01/19/2024] Open
Abstract
Mitotic centrosomes assemble when centrioles recruit large amounts of pericentriolar material (PCM) around themselves. In early C. elegans embryos, mitotic centrosome size appears to be set by the limiting amount of a key component. In Drosophila syncytial embryos, thousands of mitotic centrosomes are assembled as the embryo proceeds through 13 rounds of rapid nuclear division, driven by a core cell cycle oscillator. These divisions slow during nuclear cycles 11-13, and we find that centrosomes respond by reciprocally decreasing their growth rate, but increasing their growth period-so that they grow to a relatively consistent size at each cycle. At the start of each cycle, moderate CCO activity initially promotes centrosome growth, in part by stimulating Polo/PLK1 recruitment to centrosomes. Later in each cycle, high CCO activity inhibits centrosome growth by suppressing the centrosomal recruitment and/or maintenance of centrosome proteins. Thus, in fly embryos, mitotic centrosome size appears to be regulated predominantly by the core cell cycle oscillator, rather than by the depletion of a limiting component.
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Affiliation(s)
- Siu-Shing Wong
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Alan Wainman
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Saroj Saurya
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK
| | - Jordan W Raff
- Sir William Dunn School of Pathology, University of Oxford, Oxford, OX1 3RE, UK.
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Mayer A, McLaughlin G, Gladfelter A, Glass NL, Mela A, Roper M. Syncytial Assembly Lines: Consequences of Multinucleate Cellular Compartments for Fungal Protein Synthesis. Results Probl Cell Differ 2024; 71:159-183. [PMID: 37996678 DOI: 10.1007/978-3-031-37936-9_9] [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: 11/25/2023]
Abstract
Fast growth and prodigious cellular outputs make fungi powerful tools in biotechnology. Recent modeling work has exposed efficiency gains associated with dividing the labor of transcription over multiple nuclei, and experimental innovations are opening new windows on the capacities and adaptations that allow nuclei to behave autonomously or in coordination while sharing a single, common cytoplasm. Although the motivation of our review is to motivate and connect recent work toward a greater understanding of fungal factories, we use the analogy of the assembly line as an organizing idea for studying coordinated gene expression, generally.
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Affiliation(s)
- Alex Mayer
- Department of Mathematics, University of California Los Angeles, Los Angeles, CA, USA
| | - Grace McLaughlin
- Department of Cell Biology, Duke University, Durham, NC, USA
- Department of Biology, University of North Carolina Chapel Hill, Chapel Hill, NC, USA
| | - Amy Gladfelter
- Department of Cell Biology, Duke University, Durham, NC, USA
| | - N Louise Glass
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, USA
| | - Alexander Mela
- Department of Plant and Microbial Biology, University of California Berkeley, Berkeley, CA, USA
| | - Marcus Roper
- Department of Mathematics, University of California Los Angeles, Los Angeles, CA, USA.
- Department of Computational Medicine, University of California Los Angeles, Los Angeles, CA, USA.
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Hernández-López C, Puliafito A, Xu Y, Lu Z, Di Talia S, Vergassola M. Two-fluid dynamics and micron-thin boundary layers shape cytoplasmic flows in early Drosophila embryos. Proc Natl Acad Sci U S A 2023; 120:e2302879120. [PMID: 37878715 PMCID: PMC10622894 DOI: 10.1073/pnas.2302879120] [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: 02/20/2023] [Accepted: 08/22/2023] [Indexed: 10/27/2023] Open
Abstract
Cytoplasmic flows are widely emerging as key functional players in development. In early Drosophila embryos, flows drive the spreading of nuclei across the embryo. Here, we combine hydrodynamic modeling with quantitative imaging to develop a two-fluid model that features an active actomyosin gel and a passive viscous cytosol. Gel contractility is controlled by the cell cycle oscillator, the two fluids being coupled by friction. In addition to recapitulating experimental flow patterns, our model explains observations that remained elusive and makes a series of predictions. First, the model captures the vorticity of cytosolic flows, which highlights deviations from Stokes' flow that were observed experimentally but remained unexplained. Second, the model reveals strong differences in the gel and cytosol motion. In particular, a micron-sized boundary layer is predicted close to the cortex, where the gel slides tangentially while the cytosolic flow cannot slip. Third, the model unveils a mechanism that stabilizes the spreading of nuclei with respect to perturbations of their initial positions. This self-correcting mechanism is argued to be functionally important for proper nuclear spreading. Fourth, we use our model to analyze the effects of flows on the transport of the morphogen Bicoid and the establishment of its gradients. Finally, the model predicts that the flow strength should be reduced if the shape of the domain is more round, which is experimentally confirmed in Drosophila mutants. Thus, our two-fluid model explains flows and nuclear positioning in early Drosophila, while making predictions that suggest novel future experiments.
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Affiliation(s)
| | | | - Yitong Xu
- Department of Cell Biology, Duke University Medical Center, Durham, NC27710
| | - Ziqi Lu
- Department of Cell Biology, Duke University Medical Center, Durham, NC27710
| | - Stefano Di Talia
- Department of Cell Biology, Duke University Medical Center, Durham, NC27710
| | - Massimo Vergassola
- Department of Physics, École Normale Supérieure, Paris75005, France
- Department of Physics, University of California, San Diego, CA92075
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Chen PT, Zoller B, Levo M, Gregor T. Gene Activity as the Predictive Indicator for Transcriptional Bursting Dynamics. ARXIV 2023:arXiv:2304.08770v2. [PMID: 37131882 PMCID: PMC10153294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Transcription commonly occurs in bursts, with alternating productive (ON) and quiescent (OFF) periods, governing mRNA production rates. Yet, how transcription is regulated through bursting dynamics remains unresolved. In this study, we conduct real-time measurements of endogenous transcriptional bursting with single-mRNA sensitivity. Leveraging the diverse transcriptional activities in early fly embryos, we uncover stringent relationships between bursting parameters. Specifically, we find that the durations of ON and OFF periods are linked. Regardless of the developmental stage or body-axis position, gene activity levels predict the average ON and OFF periods of individual alleles. Lowly transcribing alleles predominantly modulate OFF durations (burst frequency), while highly transcribing alleles primarily tune ON durations (burst size). Importantly, these relationships persist even under perturbation of cis-regulatory elements or trans-factors. This suggests a novel mechanistic constraint governing bursting dynamics rather than a modular control of distinct parameters by distinct regulatory processes. Our study provides a foundation for future investigations into the molecular mechanisms underpinning spatiotemporal transcriptional control.
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Affiliation(s)
- Po-Ta Chen
- Joseph Henry Laboratories of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Benjamin Zoller
- Joseph Henry Laboratories of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
- Department of Stem Cell and Developmental Biology, CNRS UMR3738 Paris Cité, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France
| | - Michal Levo
- Joseph Henry Laboratories of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Thomas Gregor
- Joseph Henry Laboratories of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
- Department of Stem Cell and Developmental Biology, CNRS UMR3738 Paris Cité, Institut Pasteur, 25 rue du Docteur Roux, 75015 Paris, France
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López CH, Puliafito A, Xu Y, Lu Z, Di Talia S, Vergassola M. Two-fluid dynamics and micron-thin boundary layers shape cytoplasmic flows in early Drosophila embryos. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.16.532979. [PMID: 36993669 PMCID: PMC10055070 DOI: 10.1101/2023.03.16.532979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Cytoplasmic flows are widely emerging as key functional players in development. In early Drosophila embryos, flows drive the spreading of nuclei across the embryo. Here, we combine hydrodynamic modeling with quantitative imaging to develop a two-fluid model that features an active actomyosin gel and a passive viscous cytosol. Gel contractility is controlled by the cell cycle oscillator, the two fluids being coupled by friction. In addition to recapitulating experimental flow patterns, our model explains observations that remained elusive, and makes a series of new predictions. First, the model captures the vorticity of cytosolic flows, which highlights deviations from Stokes' flow that were observed experimentally but remained unexplained. Second, the model reveals strong differences in the gel and cytosol motion. In particular, a micron-sized boundary layer is predicted close to the cortex, where the gel slides tangentially whilst the cytosolic flow cannot slip. Third, the model unveils a mechanism that stabilizes the spreading of nuclei with respect to perturbations of their initial positions. This self-correcting mechanism is argued to be functionally important for proper nuclear spreading. Fourth, we use our model to analyze the effects of flows on the transport of the morphogen Bicoid, and the establishment of its gradients. Finally, the model predicts that the flow strength should be reduced if the shape of the domain is more round, which is experimentally confirmed in Drosophila mutants. Thus, our two-fluid model explains flows and nuclear positioning in early Drosophila, while making predictions that suggest novel future experiments.
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Affiliation(s)
| | - Alberto Puliafito
- Department of Oncology, University of Turin, 10060 Candiolo, Italy
- Candiolo Cancer Institute, FPO - IRCCS, Str. Prov. 142, km 3.95, 10060 Candiolo, Italy
| | - Yitong Xu
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710 USA and
| | - Ziqi Lu
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710 USA and
| | - Stefano Di Talia
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710 USA and
| | - Massimo Vergassola
- École Normale Supérieure, 75005 Paris, France
- Department of Physics, University of California San Diego, San Diego, CA 92075, USA
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Cell cycle: Making waves to coordinate the entry into mitosis. Curr Biol 2022; 32:R1262-R1264. [PMID: 36413966 DOI: 10.1016/j.cub.2022.10.030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
How do very large cells coordinate their entry into mitosis? A new study shows that the bistability of the Cdk/Cyclin system allows cells to generate either 'trigger waves' or 'sweep waves' that drive cells into mitosis in different ways with distinct consequences.
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