1
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Htet PH, Avezov E, Lauga E. Fluid mechanics of luminal transport in actively contracting endoplasmic reticulum. eLife 2024; 13:RP93518. [PMID: 39671235 PMCID: PMC11643642 DOI: 10.7554/elife.93518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2024] Open
Abstract
The endoplasmic reticulum (ER), the largest cellular compartment, harbours the machinery for the biogenesis of secretory proteins and lipids, calcium storage/mobilisation, and detoxification. It is shaped as layered membranous sheets interconnected with a network of tubules extending throughout the cell. Understanding the influence of the ER morphology dynamics on molecular transport may offer clues to rationalising neuro-pathologies caused by ER morphogen mutations. It remains unclear, however, how the ER facilitates its intra-luminal mobility and homogenises its content. It has been recently proposed that intra-luminal transport may be enabled by active contractions of ER tubules. To surmount the barriers to empirical studies of the minuscule spatial and temporal scales relevant to ER nanofluidics, here we exploit the principles of viscous fluid dynamics to generate a theoretical physical model emulating in silico the content motion in actively contracting nanoscopic tubular networks. The computational model reveals the luminal particle speeds, and their impact in facilitating active transport, of the active contractile behaviour of the different ER components along various time-space parameters. The results of the model indicate that reproducing transport with velocities similar to those reported experimentally in single-particle tracking would require unrealistically high values of tubule contraction site length and rate. Considering further nanofluidic scenarios, we show that width contractions of the ER's flat domains (perinuclear sheets) generate local flows with only a short-range effect on luminal transport. Only contractions of peripheral sheets can reproduce experimental measurements, provided they are able to contract fast enough.
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Affiliation(s)
- Pyae Hein Htet
- Department of Applied Mathematics and Theoretical Physics, University of CambridgeCambridgeUnited Kingdom
| | - Edward Avezov
- UK Dementia Research Institute at University of Cambridge, Department of Clinical Neurosciences, University of CambridgeCambridgeUnited Kingdom
| | - Eric Lauga
- Department of Applied Mathematics and Theoretical Physics, University of CambridgeCambridgeUnited Kingdom
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2
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Cebrián-Lacasa D, Leda M, Goryachev AB, Gelens L. Wave-driven phase wave patterns in a ring of FitzHugh-Nagumo oscillators. Phys Rev E 2024; 110:054208. [PMID: 39690647 DOI: 10.1103/physreve.110.054208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Accepted: 09/24/2024] [Indexed: 12/19/2024]
Abstract
We explore a biomimetic model that simulates a cell, with the internal cytoplasm represented by a two-dimensional circular domain and the external cortex by a surrounding ring, both modeled using FitzHugh-Nagumo systems. The external ring is dynamically influenced by a pacemaker-driven wave originating from the internal domain, leading to the emergence of three distinct dynamical states based on the varying strengths of coupling. The range of dynamics observed includes phase patterning, the propagation of phase waves, and interactions between traveling and phase waves. A simplified linear model effectively explains the mechanisms behind the variety of phase patterns observed, providing insights into the complex interplay between a cell's internal and external environments.
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Affiliation(s)
| | | | | | - Lendert Gelens
- Laboratory of Dynamics in Biological Systems, Department of Cellular and Molecular Medicine, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
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3
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Burkart T, Müller BJ, Frey E. Dimensionality reduction in bulk-boundary reaction-diffusion systems. Phys Rev E 2024; 110:034412. [PMID: 39425305 DOI: 10.1103/physreve.110.034412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2024] [Accepted: 07/26/2024] [Indexed: 10/21/2024]
Abstract
Intracellular protein patterns regulate many vital cellular functions, such as the processing of spatiotemporal information or the control of shape deformations. To do so, pattern-forming systems can be sensitive to the cell geometry by means of coupling the protein dynamics on the cell membrane to dynamics in the cytosol. Recent studies demonstrated that modeling the cytosolic dynamics in terms of an averaged protein pool disregards possibly crucial aspects of the pattern formation, most importantly concentration gradients normal to the membrane. At the same time, the coupling of two domains (surface and volume) with different dimensions renders many standard tools for the numerical analysis of self-organizing systems inefficient. Here, we present a generic framework for projecting the cytosolic dynamics onto the lower-dimensional surface that respects the influence of cytosolic concentration gradients in static and evolving geometries. This method uses a priori physical information about the system to approximate the cytosolic dynamics by a small number of dominant characteristic concentration profiles (basis), akin to basis transformations of finite element methods. As a proof of concept, we apply our framework to a toy model for volume-dependent interrupted coarsening, evaluate the accuracy of the results for various basis choices, and discuss the optimal basis choice for biologically relevant systems. Our analysis presents an efficient yet accurate method for analyzing pattern formation with surface-volume coupling in evolving geometries.
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4
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Nikalayevich E, Letort G, de Labbey G, Todisco E, Shihabi A, Turlier H, Voituriez R, Yahiatene M, Pollet-Villard X, Innocenti M, Schuh M, Terret ME, Verlhac MH. Aberrant cortex contractions impact mammalian oocyte quality. Dev Cell 2024; 59:841-852.e7. [PMID: 38387459 DOI: 10.1016/j.devcel.2024.01.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 12/18/2023] [Accepted: 01/26/2024] [Indexed: 02/24/2024]
Abstract
The cortex controls cell shape. In mouse oocytes, the cortex thickens in an Arp2/3-complex-dependent manner, ensuring chromosome positioning and segregation. Surprisingly, we identify that mouse oocytes lacking the Arp2/3 complex undergo cortical actin remodeling upon division, followed by cortical contractions that are unprecedented in mammalian oocytes. Using genetics, imaging, and machine learning, we show that these contractions stir the cytoplasm, resulting in impaired organelle organization and activity. Oocyte capacity to avoid polyspermy is impacted, leading to a reduced female fertility. We could diminish contractions and rescue cytoplasmic anomalies. Similar contractions were observed in human oocytes collected as byproducts during IVF (in vitro fertilization) procedures. These contractions correlate with increased cytoplasmic motion, but not with defects in spindle assembly or aneuploidy in mice or humans. Our study highlights a multiscale effect connecting cortical F-actin, contractions, and cytoplasmic organization and affecting oocyte quality, with implications for female fertility.
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Affiliation(s)
- Elvira Nikalayevich
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, Université PSL, CNRS, INSERM, 75005 Paris, France
| | - Gaëlle Letort
- Department of Developmental and Stem Cell Biology, Institut Pasteur, CNRS UMR 3738, Université Paris Cité, 25 rue du Dr. Roux, 75015 Paris, France
| | - Ghislain de Labbey
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, Université PSL, CNRS, INSERM, 75005 Paris, France
| | - Elena Todisco
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Anastasia Shihabi
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, Université PSL, CNRS, INSERM, 75005 Paris, France
| | - Hervé Turlier
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, Université PSL, CNRS, INSERM, 75005 Paris, France
| | - Raphaël Voituriez
- Laboratoire de Physique Théorique de la Matière Condensée (LPTMC), Laboratoire Jean Perrin, CNRS, Sorbonne Université, Paris, France
| | - Mohamed Yahiatene
- Centre Assistance Médicale à la Procréation Nataliance, Groupe Mlab, Pôle Santé Oréliance, Saran, France
| | - Xavier Pollet-Villard
- Centre Assistance Médicale à la Procréation Nataliance, Groupe Mlab, Pôle Santé Oréliance, Saran, France
| | - Metello Innocenti
- Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, 20126 Milan, Italy
| | - Melina Schuh
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Marie-Emilie Terret
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, Université PSL, CNRS, INSERM, 75005 Paris, France.
| | - Marie-Hélène Verlhac
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, Université PSL, CNRS, INSERM, 75005 Paris, France.
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5
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Caballero-Mancebo S, Shinde R, Bolger-Munro M, Peruzzo M, Szep G, Steccari I, Labrousse-Arias D, Zheden V, Merrin J, Callan-Jones A, Voituriez R, Heisenberg CP. Friction forces determine cytoplasmic reorganization and shape changes of ascidian oocytes upon fertilization. NATURE PHYSICS 2024; 20:310-321. [PMID: 38370025 PMCID: PMC10866705 DOI: 10.1038/s41567-023-02302-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Accepted: 10/23/2023] [Indexed: 02/20/2024]
Abstract
Contraction and flow of the actin cell cortex have emerged as a common principle by which cells reorganize their cytoplasm and take shape. However, how these cortical flows interact with adjacent cytoplasmic components, changing their form and localization, and how this affects cytoplasmic organization and cell shape remains unclear. Here we show that in ascidian oocytes, the cooperative activities of cortical actomyosin flows and deformation of the adjacent mitochondria-rich myoplasm drive oocyte cytoplasmic reorganization and shape changes following fertilization. We show that vegetal-directed cortical actomyosin flows, established upon oocyte fertilization, lead to both the accumulation of cortical actin at the vegetal pole of the zygote and compression and local buckling of the adjacent elastic solid-like myoplasm layer due to friction forces generated at their interface. Once cortical flows have ceased, the multiple myoplasm buckles resolve into one larger buckle, which again drives the formation of the contraction pole-a protuberance of the zygote's vegetal pole where maternal mRNAs accumulate. Thus, our findings reveal a mechanism where cortical actomyosin network flows determine cytoplasmic reorganization and cell shape by deforming adjacent cytoplasmic components through friction forces.
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Affiliation(s)
| | - Rushikesh Shinde
- Laboratoire de Matière et Systèmes Complexes, Université de Paris Cité and CNRS, Paris, France
| | | | - Matilda Peruzzo
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | | | - Irene Steccari
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | | | - Vanessa Zheden
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Jack Merrin
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Andrew Callan-Jones
- Laboratoire de Matière et Systèmes Complexes, Université de Paris Cité and CNRS, Paris, France
| | - Raphaël Voituriez
- Laboratoire Jean Perrin, Sorbonne Université and CNRS, Paris, France
- Laboratoire de Physique Théorique de la Matière Condensée, Sorbonne Université and CNRS, Paris, France
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6
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Rombouts J, Elliott J, Erzberger A. Forceful patterning: theoretical principles of mechanochemical pattern formation. EMBO Rep 2023; 24:e57739. [PMID: 37916772 PMCID: PMC10792592 DOI: 10.15252/embr.202357739] [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: 06/30/2023] [Revised: 09/21/2023] [Accepted: 09/27/2023] [Indexed: 11/03/2023] Open
Abstract
Biological pattern formation is essential for generating and maintaining spatial structures from the scale of a single cell to tissues and even collections of organisms. Besides biochemical interactions, there is an important role for mechanical and geometrical features in the generation of patterns. We review the theoretical principles underlying different types of mechanochemical pattern formation across spatial scales and levels of biological organization.
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Affiliation(s)
- Jan Rombouts
- Cell Biology and Biophysics
UnitEuropean Molecular Biology Laboratory (EMBL)HeidelbergGermany
- Developmental Biology Unit, European Molecular Biology Laboratory
(EMBL)HeidelbergGermany
| | - Jenna Elliott
- Cell Biology and Biophysics
UnitEuropean Molecular Biology Laboratory (EMBL)HeidelbergGermany
- Department of Physics and
AstronomyHeidelberg UniversityHeidelbergGermany
| | - Anna Erzberger
- Cell Biology and Biophysics
UnitEuropean Molecular Biology Laboratory (EMBL)HeidelbergGermany
- Department of Physics and
AstronomyHeidelberg UniversityHeidelbergGermany
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7
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Nalbant P, Wagner J, Dehmelt L. Direct investigation of cell contraction signal networks by light-based perturbation methods. Pflugers Arch 2023; 475:1439-1452. [PMID: 37851146 DOI: 10.1007/s00424-023-02864-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 08/21/2023] [Accepted: 09/21/2023] [Indexed: 10/19/2023]
Abstract
Cell contraction plays an important role in many physiological and pathophysiological processes. This includes functions in skeletal, heart, and smooth muscle cells, which lead to highly coordinated contractions of multicellular assemblies, and functions in non-muscle cells, which are often highly localized in subcellular regions and transient in time. While the regulatory processes that control cell contraction in muscle cells are well understood, much less is known about cell contraction in non-muscle cells. In this review, we focus on the mechanisms that control cell contraction in space and time in non-muscle cells, and how they can be investigated by light-based methods. The review particularly focusses on signal networks and cytoskeletal components that together control subcellular contraction patterns to perform functions on the level of cells and tissues, such as directional migration and multicellular rearrangements during development. Key features of light-based methods that enable highly local and fast perturbations are highlighted, and how experimental strategies can capitalize on these features to uncover causal relationships in the complex signal networks that control cell contraction.
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Affiliation(s)
- Perihan Nalbant
- Department of Molecular Cell Biology, Center of Medical Biotechnology, University of Duisburg-Essen, Room T03 R01 D33, Universitätsstrasse 2, 45141, Essen, Germany.
| | - Jessica Wagner
- Department of Molecular Cell Biology, Center of Medical Biotechnology, University of Duisburg-Essen, Room T03 R01 D33, Universitätsstrasse 2, 45141, Essen, Germany
| | - Leif Dehmelt
- Department of Systemic Cell Biology, Fakultät für Chemie und Chemische Biologie, Max Planck Institute of Molecular Physiology, and Dortmund University of Technology, Room CP-02-157, Otto-Hahn-Str. 4a, 44227, Dortmund, Germany.
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8
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Fei C, Dunkel J. Fly embryo nuclei riding on two-fluid flow. Proc Natl Acad Sci U S A 2023; 120:e2317219120. [PMID: 37939065 PMCID: PMC10665796 DOI: 10.1073/pnas.2317219120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2023] Open
Affiliation(s)
- Chenyi Fei
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Jörn Dunkel
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA02139
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9
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Htet PH, Lauga E. Cortex-driven cytoplasmic flows in elongated cells: fluid mechanics and application to nuclear transport in Drosophila embryos. J R Soc Interface 2023; 20:20230428. [PMID: 37963561 PMCID: PMC10645513 DOI: 10.1098/rsif.2023.0428] [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: 07/26/2023] [Accepted: 10/23/2023] [Indexed: 11/16/2023] Open
Abstract
The Drosophila melanogaster embryo, an elongated multi-nucleated cell, is a classical model system for eukaryotic development and morphogenesis. Recent work has shown that bulk cytoplasmic flows, driven by cortical contractions along the walls of the embryo, enable the uniform spreading of nuclei along the anterior-posterior axis necessary for proper embryonic development. Here, we propose two mathematical models to characterize cytoplasmic flows driven by tangential cortical contractions in elongated cells. Assuming Newtonian fluid flow at low Reynolds number in a spheroidal cell, we first compute the flow field exactly, thereby bypassing the need for numerical computations. We then apply our results to recent experiments on nuclear transport in cell cycles 4-6 of Drosophila embryo development. By fitting the cortical contractions in our model to measurements, we reveal that experimental cortical flows enable near-optimal axial spreading of nuclei. A second mathematical approach, applicable to general elongated cell geometries, exploits a long-wavelength approximation to produce an even simpler solution, with errors below [Formula: see text] compared with the full model. An application of this long-wavelength result to transport leads to fully analytical solutions for the nuclear concentration that capture the essential physics of the system, including optimal axial spreading of nuclei.
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Affiliation(s)
- Pyae Hein Htet
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, UK
| | - Eric Lauga
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, UK
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10
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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: 4] [Impact Index Per Article: 4.0] [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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11
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Dow LP, Parmar T, Marchetti MC, Pruitt BL. Engineering tools for quantifying and manipulating forces in epithelia. BIOPHYSICS REVIEWS 2023; 4:021303. [PMID: 38510344 PMCID: PMC10903508 DOI: 10.1063/5.0142537] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2023] [Accepted: 04/20/2023] [Indexed: 03/22/2024]
Abstract
The integrity of epithelia is maintained within dynamic mechanical environments during tissue development and homeostasis. Understanding how epithelial cells mechanosignal and respond collectively or individually is critical to providing insight into developmental and (patho)physiological processes. Yet, inferring or mimicking mechanical forces and downstream mechanical signaling as they occur in epithelia presents unique challenges. A variety of in vitro approaches have been used to dissect the role of mechanics in regulating epithelia organization. Here, we review approaches and results from research into how epithelial cells communicate through mechanical cues to maintain tissue organization and integrity. We summarize the unique advantages and disadvantages of various reduced-order model systems to guide researchers in choosing appropriate experimental systems. These model systems include 3D, 2D, and 1D micromanipulation methods, single cell studies, and noninvasive force inference and measurement techniques. We also highlight a number of in silico biophysical models that are informed by in vitro and in vivo observations. Together, a combination of theoretical and experimental models will aid future experiment designs and provide predictive insight into mechanically driven behaviors of epithelial dynamics.
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Affiliation(s)
| | - Toshi Parmar
- Department of Physics, University of California Santa Barbara, Santa Barbara, California 93106, USA
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12
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Boquet-Pujadas A, Olivo-Marin JC. Reformulating Optical Flow to Solve Image-Based Inverse Problems and Quantify Uncertainty. IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE 2023; 45:6125-6141. [PMID: 36040935 DOI: 10.1109/tpami.2022.3202855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
From meteorology to medical imaging and cell mechanics, many scientific domains use inverse problems (IPs) to extract physical measurements from image movement. To this end, motion estimation methods such as optical flow (OF) pre-process images into motion data to feed the IP, which then inverts for the measurements through a physical model. However, this combined OFIP pipeline exacerbates the ill-posedness inherent to each technique, propagating errors and preventing uncertainty quantification. We introduce a Bayesian PDE-constrained framework that transforms visual information directly into physical measurements in the context of probability distributions. The posterior mean is a constrained IP that tracks brightness while satisfying the physical model, thereby translating the aperture problem from the motion to the underlying physics; whereas the posterior covariance derives measurement error out of image noise. As we illustrate with traction force microscopy, our approach offers several advantages: more accurate reconstructions; unprecedented flexibility in experiment design (e.g., arbitrary boundary conditions); and the exclusivity of measurement error, central to empirical science, yet still unavailable under the OFIP strategy.
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13
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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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14
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Abstract
Cells are the smallest building blocks of all living eukaryotic organisms, usually ranging from a couple of micrometers (for example, platelets) to hundreds of micrometers (for example, neurons and oocytes) in size. In eukaryotic cells that are more than 100 µm in diameter, very often a self-organized large-scale movement of cytoplasmic contents, known as cytoplasmic streaming, occurs to compensate for the physical constraints of large cells. In this Review, we discuss cytoplasmic streaming in multiple cell types and the mechanisms driving this event. We particularly focus on the molecular motors responsible for cytoplasmic movements and the biological roles of cytoplasmic streaming in cells. Finally, we describe bulk intercellular flow that transports cytoplasmic materials to the oocyte from its sister germline cells to drive rapid oocyte growth.
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Affiliation(s)
- Wen Lu
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611-3008, USA
| | - Vladimir I. Gelfand
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611-3008, USA
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15
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Najafi J, Dmitrieff S, Minc N. Size- and position-dependent cytoplasm viscoelasticity through hydrodynamic interactions with the cell surface. Proc Natl Acad Sci U S A 2023; 120:e2216839120. [PMID: 36802422 PMCID: PMC9992773 DOI: 10.1073/pnas.2216839120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Accepted: 01/23/2023] [Indexed: 02/23/2023] Open
Abstract
Many studies of cytoplasm rheology have focused on small components in the submicrometer scale. However, the cytoplasm also baths large organelles like nuclei, microtubule asters, or spindles that often take significant portions of cells and move across the cytoplasm to regulate cell division or polarization. Here, we translated passive components of sizes ranging from few up to ~50 percents of the cell diameter, through the vast cytoplasm of live sea urchin eggs, with calibrated magnetic forces. Creep and relaxation responses indicate that for objects larger than the micron size, the cytoplasm behaves as a Jeffreys material, viscoelastic at short timescales, and fluidizing at longer times. However, as component size approached that of cells, cytoplasm viscoelastic resistance increased in a nonmonotonic manner. Flow analysis and simulations suggest that this size-dependent viscoelasticity emerges from hydrodynamic interactions between the moving object and the static cell surface. This effect also yields to position-dependent viscoelasticity with objects initially closer to the cell surface being harder to displace. These findings suggest that the cytoplasm hydrodynamically couples large organelles to the cell surface to restrain their motion, with important implications for cell shape sensing and cellular organization.
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Affiliation(s)
- Javad Najafi
- Université de Paris, CNRS, Institut Jacques Monod,75006Paris, France
- Equipe Labellisée Ligue Contre le Cancer, 75013Paris, France
| | - Serge Dmitrieff
- Université de Paris, CNRS, Institut Jacques Monod,75006Paris, France
- Equipe Labellisée Ligue Contre le Cancer, 75013Paris, France
| | - Nicolas Minc
- Université de Paris, CNRS, Institut Jacques Monod,75006Paris, France
- Equipe Labellisée Ligue Contre le Cancer, 75013Paris, France
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16
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Park M, Lee K, Granick S. Response of vesicle shapes to dense inner active matter. SOFT MATTER 2022; 18:6419-6425. [PMID: 35979740 DOI: 10.1039/d2sm00781a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We consider experimentally the Takatori-Sahu model of vesicle shape fluctuations induced by enclosed active matter, a model till present tested only in the absence of collective motion because few enclosed bacteria were used to generate the desired active motion (S. C. Takatori and A. Sahu, Phys. Rev. Lett., 2020, 124, 158102). Using deformable giant unilamellar vesicles (GUVs) and phase contrast microscopy, we extract the mode-dependence of GUV shape fluctuations when hundreds of E. coli bacteria are contained within each GUV. In the microscope focal plane, patterns of collective bacteria flow include vortex flow, dipolar flow, and chaotic motion, all of which influence the GUV shapes. The Takatori-Sahu model generalizes well to this situation if one considers the moving element to be the experimentally-determined size of the collecively-moving flock.
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Affiliation(s)
- Myeonggon Park
- Center for Soft and Living Matter, Institute for Basic Science, Ulsan, South Korea.
- Department of Physics, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea
| | - Kisung Lee
- Center for Soft and Living Matter, Institute for Basic Science, Ulsan, South Korea.
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea
| | - Steve Granick
- Center for Soft and Living Matter, Institute for Basic Science, Ulsan, South Korea.
- Department of Physics, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea
- Department of Chemistry, Ulsan National Institute of Science and Technology (UNIST), Ulsan, South Korea
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17
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Pal D, Visconti F, Sepúlveda-Ramírez SP, Swartz SZ, Shuster CB. Use of Echinoderm Gametes and Early Embryos for Studying Meiosis and Mitosis. Methods Mol Biol 2022; 2415:1-17. [PMID: 34972942 DOI: 10.1007/978-1-0716-1904-9_1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The early embryos of sea urchins and other echinoderms have served as experimental models for the study of cell division since the nineteenth century. Their rapid development, optical clarity, and ease of manipulation continue to offer advantages for studying spindle assembly and cytokinesis. In the absence of transgenic lines, alternative strategies must be employed to visualize microtubules and actin. Here, we describe methods to visualize actin and microtubule using either purified, recombinant proteins, or probes in in vitro-transcribed mRNAs.
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Affiliation(s)
- Debadrita Pal
- Department of Biology, New Mexico State University, Las Cruces, NM, USA
| | | | | | | | - Charles B Shuster
- Department of Biology, New Mexico State University, Las Cruces, NM, USA.
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18
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Abstract
Understanding the mechanisms of embryonic cell cycles is a central goal of developmental biology, as the regulation of the cell cycle must be closely coordinated with other events during early embryogenesis. Quantitative imaging approaches have recently begun to reveal how the cell cycle oscillator is controlled in space and time, and how it is integrated with mechanical signals to drive morphogenesis. Here, we discuss how the Drosophila embryo has served as an excellent model for addressing the molecular and physical mechanisms of embryonic cell cycles, with comparisons to other model systems to highlight conserved and species-specific mechanisms. We describe how the rapid cleavage divisions characteristic of most metazoan embryos require chemical waves and cytoplasmic flows to coordinate morphogenesis across the large expanse of the embryo. We also outline how, in the late cleavage divisions, the cell cycle is inter-regulated with the activation of gene expression to ensure a reliable maternal-to-zygotic transition. Finally, we discuss how precise transcriptional regulation of the timing of mitosis ensures that tissue morphogenesis and cell proliferation are tightly controlled during gastrulation.
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Affiliation(s)
| | - Stefano Di Talia
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27705, USA
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19
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Dreher Y, Jahnke K, Bobkova E, Spatz JP, Göpfrich K. Division and Regrowth of Phase‐Separated Giant Unilamellar Vesicles**. Angew Chem Int Ed Engl 2021. [DOI: 10.1002/ange.202014174] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Yannik Dreher
- Biophysical Engineering Group Max Planck Institute for Medical Research Jahnstraße 29 69120 Heidelberg Germany
- Department of Physics and Astronomy Heidelberg University 69120 Heidelberg Germany
| | - Kevin Jahnke
- Biophysical Engineering Group Max Planck Institute for Medical Research Jahnstraße 29 69120 Heidelberg Germany
- Department of Physics and Astronomy Heidelberg University 69120 Heidelberg Germany
| | - Elizaveta Bobkova
- Biophysical Engineering Group Max Planck Institute for Medical Research Jahnstraße 29 69120 Heidelberg Germany
- Department of Physics and Astronomy Heidelberg University 69120 Heidelberg Germany
| | - Joachim P. Spatz
- Department of Cellular Biophysics Max Planck Institute for Medical Research Jahnstraße 29 69120 Heidelberg Germany
- Institute for Molecular Systems Engineering (IMSE) Heidelberg University Im Neuenheimer Feld 225 69120 Heidelberg Germany
- Max Planck School Matter to Life Jahnstraße 29 69120 Heidelberg Germany
| | - Kerstin Göpfrich
- Biophysical Engineering Group Max Planck Institute for Medical Research Jahnstraße 29 69120 Heidelberg Germany
- Department of Physics and Astronomy Heidelberg University 69120 Heidelberg Germany
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20
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Iwayama H, Yamashita M. Quantitative evaluation of intercellular local deformation of human oocytes during Piezo-assisted intracytoplasmic sperm injection using video-based motion analysis. F&S SCIENCE 2021; 2:124-134. [PMID: 35559747 DOI: 10.1016/j.xfss.2021.01.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 12/22/2020] [Accepted: 01/08/2021] [Indexed: 06/15/2023]
Abstract
OBJECTIVE To evaluate the relationship between the quantitative properties of local deformation of the ooplasm during Piezo-assisted intracytoplasmic sperm injection (Piezo-ICSI) and oocyte developmental fate after Piezo-ICSI. DESIGN Video-based motion analysis and case-control study. SETTING Private fertility center. PATIENT(S) A total of 99 couples assigned to the standard Piezo-ICSI program. INTERVENTION(S) Video recordings of the sperm injection process during Piezo-ICSI. MAIN OUTCOME MEASURE(S) Quantitative deformation properties consisting of the orientation of deformation perpendicular (Perp) or parallel (Para) to the oolemma and the mechanical response of the ooplasm (elongation, contraction, and total): Perp-elongation, Perp-contraction, Perp-total, Para-elongation, Perp-contraction, and Para-total. RESULT(S) The deformation parameters were compared among different angular ranges of 30°-60°, 60°-90°, 90°-120°, and 120°-150° (defined as 0° at the 3 o'clock puncture site). The Perp-total value at 30°-60° was significantly greater than that at the other angles (130.2 vs. 57.7-85.5, respectively) primarily due to substantially greater Perp-elongation values. The Para-total value at 30°-60° was significantly greater than that at the other angles (20.1 vs. 6.7-10.3, respectively) primarily due to substantially smaller Para-contraction values. The deformation parameters of the ooplasm adjacent to the first polar body were also compared among different developmental fates (fertilization failure, cleavage arrest, and blastocyst development). The Perp-total value of oocytes derived from blastocyst formation was significantly smaller than those derived from other developmental fates (58.1 vs. 70.0-87.3, respectively). CONCLUSION(S) The Piezo-ICSI process induced deformation with various mechanical behaviors in different regions within a single oocyte. Furthermore, the exposure of the ooplasm adjacent to the first polar body to excessive deformation was found to be a possible trigger for adverse fertilization and embryo development after Piezo-ICSI.
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21
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Dreher Y, Jahnke K, Bobkova E, Spatz JP, Göpfrich K. Division and Regrowth of Phase-Separated Giant Unilamellar Vesicles*. Angew Chem Int Ed Engl 2021; 60:10661-10669. [PMID: 33355974 PMCID: PMC8252472 DOI: 10.1002/anie.202014174] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Revised: 12/13/2020] [Indexed: 01/01/2023]
Abstract
Success in the bottom‐up assembly of synthetic cells will depend on strategies for the division of protocellular compartments. Here, we describe the controlled division of phase‐separated giant unilamellar lipid vesicles (GUVs). We derive an analytical model based on the vesicle geometry, which makes four quantitative predictions that we verify experimentally. We find that the osmolarity ratio required for division is 2
, independent of the GUV size, while asymmetric division happens at lower osmolarity ratios. Remarkably, we show that a suitable osmolarity change can be triggered by water evaporation, enzymatic decomposition of sucrose or light‐triggered uncaging of CMNB‐fluorescein. The latter provides full spatiotemporal control, such that a target GUV undergoes division whereas the surrounding GUVs remain unaffected. Finally, we grow phase‐separated vesicles from single‐phased vesicles by targeted fusion of the opposite lipid type with programmable DNA tags to enable subsequent division cycles.
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Affiliation(s)
- Yannik Dreher
- Biophysical Engineering Group, Max Planck Institute for Medical Research, Jahnstraße 29, 69120, Heidelberg, Germany.,Department of Physics and Astronomy, Heidelberg University, 69120, Heidelberg, Germany
| | - Kevin Jahnke
- Biophysical Engineering Group, Max Planck Institute for Medical Research, Jahnstraße 29, 69120, Heidelberg, Germany.,Department of Physics and Astronomy, Heidelberg University, 69120, Heidelberg, Germany
| | - Elizaveta Bobkova
- Biophysical Engineering Group, Max Planck Institute for Medical Research, Jahnstraße 29, 69120, Heidelberg, Germany.,Department of Physics and Astronomy, Heidelberg University, 69120, Heidelberg, Germany
| | - Joachim P Spatz
- Department of Cellular Biophysics, Max Planck Institute for Medical Research, Jahnstraße 29, 69120, Heidelberg, Germany.,Institute for Molecular Systems Engineering (IMSE), Heidelberg University, Im Neuenheimer Feld 225, 69120, Heidelberg, Germany.,Max Planck School Matter to Life, Jahnstraße 29, 69120, Heidelberg, Germany
| | - Kerstin Göpfrich
- Biophysical Engineering Group, Max Planck Institute for Medical Research, Jahnstraße 29, 69120, Heidelberg, Germany.,Department of Physics and Astronomy, Heidelberg University, 69120, Heidelberg, Germany
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22
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Abstract
Bioimage analysis (BIA) has historically helped study how and why cells move; biological experiments evolved in intimate feedback with the most classical image processing techniques because they contribute objectivity and reproducibility to an eminently qualitative science. Cell segmentation, tracking, and morphology descriptors are all discussed here. Using ameboid motility as a case study, these methods help us illustrate how proper quantification can augment biological data, for example, by choosing mathematical representations that amplify initially subtle differences, by statistically uncovering general laws or by integrating physical insight. More recently, the non-invasive nature of quantitative imaging is fertilizing two blooming fields: mechanobiology, where many biophysical measurements remain inaccessible, and microenvironments, where the quest for physiological relevance has exploded data size. From relief to remedy, this trend indicates that BIA is to become a main vector of biological discovery as human visual analysis struggles against ever more complex data.
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Affiliation(s)
- Aleix Boquet-Pujadas
- Institut Pasteur, Bioimage Analysis Unit, 25 rue du Dr. Roux, Paris Cedex 15 75724, France
- Centre National de la Recherche Scientifique, CNRS UMR3691, Paris, France
- Sorbonne Université, Paris 75005, France
| | - Jean-Christophe Olivo-Marin
- Institut Pasteur, Bioimage Analysis Unit, 25 rue du Dr. Roux, Paris Cedex 15 75724, France
- Centre National de la Recherche Scientifique, CNRS UMR3691, Paris, France
| | - Nancy Guillén
- Institut Pasteur, Bioimage Analysis Unit, 25 rue du Dr. Roux, Paris Cedex 15 75724, France
- Centre National de la Recherche Scientifique, CNRS ERL9195, Paris, France
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23
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Pal D, Ellis A, Sepúlveda-Ramírez SP, Salgado T, Terrazas I, Reyes G, De La Rosa R, Henson JH, Shuster CB. Rac and Arp2/3-Nucleated Actin Networks Antagonize Rho During Mitotic and Meiotic Cleavages. Front Cell Dev Biol 2020; 8:591141. [PMID: 33282870 PMCID: PMC7705106 DOI: 10.3389/fcell.2020.591141] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/20/2020] [Indexed: 12/01/2022] Open
Abstract
In motile cells, the activities of the different Rho family GTPases are spatially segregated within the cell, and during cytokinesis there is evidence that this may also be the case. But while Rho’s role as the central organizer for contractile ring assembly is well established, the role of Rac and the branched actin networks it promotes is less well understood. To characterize the contributions of these proteins during cytokinesis, we manipulated Rac and Arp2/3 activity during mitosis and meiosis in sea urchin embryos and sea star oocytes. While neither Rac nor Arp2/3 were essential for early embryonic divisions, loss of either Rac or Arp2/3 activity resulted in polar body defects. Expression of activated Rac resulted in cytokinesis failure as early as the first division, and in oocytes, activated Rac suppressed both the Rho wave that traverses the oocyte prior to polar body extrusion as well as polar body formation itself. However, the inhibitory effect of Rac on cytokinesis, polar body formation and the Rho wave could be suppressed by effector-binding mutations or direct inhibition of Arp2/3. Together, these results suggest that Rac- and Arp2/3 mediated actin networks may directly antagonize Rho signaling, thus providing a potential mechanism to explain why Arp2/3-nucleated branched actin networks must be suppressed at the cell equator for successful cytokinesis.
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Affiliation(s)
- Debadrita Pal
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Andrea Ellis
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | | | - Torey Salgado
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Isabella Terrazas
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Gabriela Reyes
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Richard De La Rosa
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - John H Henson
- Department of Biology, Dickinson College, Carlisle, PA, United States
| | - Charles B Shuster
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
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24
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S Mogre S, Brown AI, Koslover EF. Getting around the cell: physical transport in the intracellular world. Phys Biol 2020; 17:061003. [PMID: 32663814 DOI: 10.1088/1478-3975/aba5e5] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Eukaryotic cells face the challenging task of transporting a variety of particles through the complex intracellular milieu in order to deliver, distribute, and mix the many components that support cell function. In this review, we explore the biological objectives and physical mechanisms of intracellular transport. Our focus is on cytoplasmic and intra-organelle transport at the whole-cell scale. We outline several key biological functions that depend on physically transporting components across the cell, including the delivery of secreted proteins, support of cell growth and repair, propagation of intracellular signals, establishment of organelle contacts, and spatial organization of metabolic gradients. We then review the three primary physical modes of transport in eukaryotic cells: diffusive motion, motor-driven transport, and advection by cytoplasmic flow. For each mechanism, we identify the main factors that determine speed and directionality. We also highlight the efficiency of each transport mode in fulfilling various key objectives of transport, such as particle mixing, directed delivery, and rapid target search. Taken together, the interplay of diffusion, molecular motors, and flows supports the intracellular transport needs that underlie a broad variety of biological phenomena.
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Affiliation(s)
- Saurabh S Mogre
- Department of Physics, University of California, San Diego, San Diego, California 92093, United States of America
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25
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Flow Induced Symmetry Breaking in a Conceptual Polarity Model. Cells 2020; 9:cells9061524. [PMID: 32585819 PMCID: PMC7349905 DOI: 10.3390/cells9061524] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 12/19/2022] Open
Abstract
Important cellular processes, such as cell motility and cell division, are coordinated by cell polarity, which is determined by the non-uniform distribution of certain proteins. Such protein patterns form via an interplay of protein reactions and protein transport. Since Turing’s seminal work, the formation of protein patterns resulting from the interplay between reactions and diffusive transport has been widely studied. Over the last few years, increasing evidence shows that also advective transport, resulting from cytosolic and cortical flows, is present in many cells. However, it remains unclear how and whether these flows contribute to protein-pattern formation. To address this question, we use a minimal model that conserves the total protein mass to characterize the effects of cytosolic flow on pattern formation. Combining a linear stability analysis with numerical simulations, we find that membrane-bound protein patterns propagate against the direction of cytoplasmic flow with a speed that is maximal for intermediate flow speed. We show that the mechanism underlying this pattern propagation relies on a higher protein influx on the upstream side of the pattern compared to the downstream side. Furthermore, we find that cytosolic flow can change the membrane pattern qualitatively from a peak pattern to a mesa pattern. Finally, our study shows that a non-uniform flow profile can induce pattern formation by triggering a regional lateral instability.
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26
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Vogel SK, Wölfer C, Ramirez-Diaz DA, Flassig RJ, Sundmacher K, Schwille P. Symmetry Breaking and Emergence of Directional Flows in Minimal Actomyosin Cortices. Cells 2020; 9:cells9061432. [PMID: 32527013 PMCID: PMC7349012 DOI: 10.3390/cells9061432] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/28/2020] [Accepted: 05/31/2020] [Indexed: 11/16/2022] Open
Abstract
Cortical actomyosin flows, among other mechanisms, scale up spontaneous symmetry breaking and thus play pivotal roles in cell differentiation, division, and motility. According to many model systems, myosin motor-induced local contractions of initially isotropic actomyosin cortices are nucleation points for generating cortical flows. However, the positive feedback mechanisms by which spontaneous contractions can be amplified towards large-scale directed flows remain mostly speculative. To investigate such a process on spherical surfaces, we reconstituted and confined initially isotropic minimal actomyosin cortices to the interfaces of emulsion droplets. The presence of ATP leads to myosin-induced local contractions that self-organize and amplify into directed large-scale actomyosin flows. By combining our experiments with theory, we found that the feedback mechanism leading to a coordinated directional motion of actomyosin clusters can be described as asymmetric cluster vibrations, caused by intrinsic non-isotropic ATP consumption with spatial confinement. We identified fingerprints of vibrational states as the basis of directed motions by tracking individual actomyosin clusters. These vibrations may represent a generic key driver of directed actomyosin flows under spatial confinement in vitro and in living systems.
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Affiliation(s)
- Sven K. Vogel
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany; (S.K.V.); (D.A.R.-D.)
| | - Christian Wölfer
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, D-39106 Magdeburg, Germany; (C.W.); (R.J.F.); (K.S.)
| | - Diego A. Ramirez-Diaz
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany; (S.K.V.); (D.A.R.-D.)
- Graduate School of Quantitative Biosciences, Ludwig-Maximilians-Universität, Feodor-Lynen-Str. 25, D-81377 Munich, Germany
| | - Robert J. Flassig
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, D-39106 Magdeburg, Germany; (C.W.); (R.J.F.); (K.S.)
- Department of Engineering, Brandenburg University of Applied Sciences, Magdeburger Str. 50, D-14770 Brandenburg, Germany
| | - Kai Sundmacher
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, D-39106 Magdeburg, Germany; (C.W.); (R.J.F.); (K.S.)
- Institute for Process Engineering, Otto von Guericke University Magdeburg, Universitätsplatz 2, D-39106 Magdeburg, Germany
| | - Petra Schwille
- Max Planck Institute of Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany; (S.K.V.); (D.A.R.-D.)
- Correspondence:
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27
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Lavi I, Meunier N, Voituriez R, Casademunt J. Motility and morphodynamics of confined cells. Phys Rev E 2020; 101:022404. [PMID: 32168566 DOI: 10.1103/physreve.101.022404] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Accepted: 12/03/2019] [Indexed: 06/10/2023]
Abstract
We introduce a minimal hydrodynamic model of polarization, migration, and deformation of a biological cell confined between two parallel surfaces. In our model, the cell is driven out of equilibrium by an active cytsokeleton force that acts on the membrane. The cell cytoplasm, described as a viscous droplet in the Darcy flow regime, contains a diffusive solute that actively transduces the applied cytoskeleton force. While fairly simple and analytically tractable, this quasi-two-dimensional model predicts a range of compelling dynamic behaviours. A linear stability analysis of the system reveals that solute activity first destabilizes a global polarization-translation mode, prompting cell motility through spontaneous symmetry breaking. At higher activity, the system crosses a series of Hopf bifurcations leading to coupled oscillations of droplet shape and solute concentration profiles. At the nonlinear level, we find traveling-wave solutions associated with unique polarized shapes that resemble experimental observations. Altogether, this model offers an analytical paradigm of active deformable systems in which viscous hydrodynamics are coupled to diffusive force transducers.
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Affiliation(s)
- Ido Lavi
- Laboratoire Jean Perrin, CNRS/Sorbonne Université, 4 Place Jussieu, 75005 Paris, France
- Departament de Fsica de la Matria Condensada, Universitat de Barcelona, Avinguda Diagonal 647, 08028 Barcelona, Spain
| | | | - Raphael Voituriez
- Laboratoire Jean Perrin, CNRS/Sorbonne Université, 4 Place Jussieu, 75005 Paris, France
- Laboratoire de Physique Théorique de la Matière Condensée, CNRS/Sorbonne Université, 4 Place Jussieu, 75005 Paris, France
| | - Jaume Casademunt
- Departament de Fsica de la Matria Condensada, Universitat de Barcelona, Avinguda Diagonal 647, 08028 Barcelona, Spain
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28
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Bächer C, Gekle S. Computational modeling of active deformable membranes embedded in three-dimensional flows. Phys Rev E 2019; 99:062418. [PMID: 31330647 DOI: 10.1103/physreve.99.062418] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2019] [Indexed: 06/10/2023]
Abstract
Active gel theory has recently been very successful in describing biologically active materials such as actin filaments or moving bacteria in temporally fixed and simple geometries such as cubes or spheres. Here we develop a computational algorithm to compute the dynamic evolution of an arbitrarily shaped, deformable thin membrane of active material embedded in a three-dimensional flowing liquid. For this, our algorithm combines active gel theory with the classical theory of thin elastic shells. To compute the actual forces resulting from active stresses, we apply a parabolic fitting procedure to the triangulated membrane surface. Active forces are then dynamically coupled via an immersed-boundary method to the surrounding fluid whose dynamics can be solved by any standard, e.g., Lattice-Boltzmann, flow solver. We validate our algorithm using the Green's functions of Berthoumieux et al. [New J. Phys. 16, 065005 (2014)10.1088/1367-2630/16/6/065005] for an active cylindrical membrane subjected (i) to a locally increased active stress and (ii) to a homogeneous active stress. For the latter scenario, we predict in addition a nonaxisymmetric instability. We highlight the versatility of our method by analyzing the flow field inside an actively deforming cell embedded in external shear flow. Further applications may be cytoplasmic streaming or active membranes in blood flows.
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Affiliation(s)
- Christian Bächer
- Biofluid Simulation and Modeling, Theoretische Physik VI, Universität Bayreuth, Universitätsstrasse 30, Bayreuth, Germany
| | - Stephan Gekle
- Biofluid Simulation and Modeling, Theoretische Physik VI, Universität Bayreuth, Universitätsstrasse 30, Bayreuth, Germany
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29
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Shamipour S, Kardos R, Xue SL, Hof B, Hannezo E, Heisenberg CP. Bulk Actin Dynamics Drive Phase Segregation in Zebrafish Oocytes. Cell 2019; 177:1463-1479.e18. [PMID: 31080065 DOI: 10.1016/j.cell.2019.04.030] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2018] [Revised: 02/07/2019] [Accepted: 04/12/2019] [Indexed: 10/26/2022]
Abstract
Segregation of maternal determinants within the oocyte constitutes the first step in embryo patterning. In zebrafish oocytes, extensive ooplasmic streaming leads to the segregation of ooplasm from yolk granules along the animal-vegetal axis of the oocyte. Here, we show that this process does not rely on cortical actin reorganization, as previously thought, but instead on a cell-cycle-dependent bulk actin polymerization wave traveling from the animal to the vegetal pole of the oocyte. This wave functions in segregation by both pulling ooplasm animally and pushing yolk granules vegetally. Using biophysical experimentation and theory, we show that ooplasm pulling is mediated by bulk actin network flows exerting friction forces on the ooplasm, while yolk granule pushing is achieved by a mechanism closely resembling actin comet formation on yolk granules. Our study defines a novel role of cell-cycle-controlled bulk actin polymerization waves in oocyte polarization via ooplasmic segregation.
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Affiliation(s)
- Shayan Shamipour
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Roland Kardos
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Shi-Lei Xue
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Björn Hof
- Institute of Science and Technology Austria, Klosterneuburg, Austria
| | - Edouard Hannezo
- Institute of Science and Technology Austria, Klosterneuburg, Austria.
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