1
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Liberali P, Schier AF. The evolution of developmental biology through conceptual and technological revolutions. Cell 2024; 187:3461-3495. [PMID: 38906136 DOI: 10.1016/j.cell.2024.05.053] [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: 04/12/2024] [Revised: 05/28/2024] [Accepted: 05/29/2024] [Indexed: 06/23/2024]
Abstract
Developmental biology-the study of the processes by which cells, tissues, and organisms develop and change over time-has entered a new golden age. After the molecular genetics revolution in the 80s and 90s and the diversification of the field in the early 21st century, we have entered a phase when powerful technologies provide new approaches and open unexplored avenues. Progress in the field has been accelerated by advances in genomics, imaging, engineering, and computational biology and by emerging model systems ranging from tardigrades to organoids. We summarize how revolutionary technologies have led to remarkable progress in understanding animal development. We describe how classic questions in gene regulation, pattern formation, morphogenesis, organogenesis, and stem cell biology are being revisited. We discuss the connections of development with evolution, self-organization, metabolism, time, and ecology. We speculate how developmental biology might evolve in an era of synthetic biology, artificial intelligence, and human engineering.
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Affiliation(s)
- Prisca Liberali
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland; University of Basel, Basel, Switzerland.
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2
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Zernicki-Glover S, Stanislawska N, Patel EM, Kavanagh YH, Meglicki M. Blastomere size in the human 2-cell embryo predicts the division order that leads to imbalanced lineage contribution to the future body. MICROPUBLICATION BIOLOGY 2024; 2024:10.17912/micropub.biology.001181. [PMID: 38841597 PMCID: PMC11151110 DOI: 10.17912/micropub.biology.001181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Figures] [Subscribe] [Scholar Register] [Received: 03/13/2024] [Revised: 04/09/2024] [Accepted: 04/19/2024] [Indexed: 06/07/2024]
Abstract
Retrospective tracing of somatic mutations predicted that most cells in the human body could be traced back to a single cell of the 2-cell stage embryo. Accordingly, a recent prospective study of the developmental trajectory of blastomeres in human embryos confirmed that progeny of the first 2-cell stage blastomere to divide generates more epiblast cells (future body). How the 2-cell blastomeres differ is unknown. Here, we show that 2-cell stage blastomeres in human embryos are asymmetric; they differ in size and the bigger blastomere divides first to 4-cell stage. We propose that this asymmetry might originate differences in cell fate.
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Affiliation(s)
| | | | - Ekta M. Patel
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, United States
| | - Yu Hua Kavanagh
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, England, United Kingdom
| | - Maciej Meglicki
- Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, England, United Kingdom
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3
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Doerr S, Zhou P, Ragkousi K. Origin and development of primary animal epithelia. Bioessays 2024; 46:e2300150. [PMID: 38009581 PMCID: PMC11164562 DOI: 10.1002/bies.202300150] [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: 08/10/2023] [Revised: 10/11/2023] [Accepted: 11/13/2023] [Indexed: 11/29/2023]
Abstract
Epithelia are the first organized tissues that appear during development. In many animal embryos, early divisions give rise to a polarized monolayer, the primary epithelium, rather than a random aggregate of cells. Here, we review the mechanisms by which cells organize into primary epithelia in various developmental contexts. We discuss how cells acquire polarity while undergoing early divisions. We describe cases where oriented divisions constrain cell arrangement to monolayers including organization on top of yolk surfaces. We finally discuss how epithelia emerge in embryos from animals that branched early during evolution and provide examples of epithelia-like arrangements encountered in single-celled eukaryotes. Although divergent and context-dependent mechanisms give rise to primary epithelia, here we trace the unifying principles underlying their formation.
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Affiliation(s)
- Sophia Doerr
- Department of Biology, Amherst College, Amherst, Massachusetts, USA
- Department of Biology, Institute of Molecular Biology, University of Oregon, Eugene, USA
| | - Phillip Zhou
- Department of Biology, Amherst College, Amherst, Massachusetts, USA
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4
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Naturale VF, Pickett MA, Feldman JL. Persistent cell contacts enable E-cadherin/HMR-1- and PAR-3-based symmetry breaking within a developing C. elegans epithelium. Dev Cell 2023; 58:1830-1846.e12. [PMID: 37552986 PMCID: PMC10592304 DOI: 10.1016/j.devcel.2023.07.008] [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: 08/12/2022] [Revised: 05/10/2023] [Accepted: 07/17/2023] [Indexed: 08/10/2023]
Abstract
Tissue-wide patterning is essential to multicellular development, requiring cells to individually generate polarity axes and coordinate them in space and time with neighbors. Using the C. elegans intestinal epithelium, we identified a patterning mechanism that is informed by cell contact lifetime asymmetry and executed via the scaffolding protein PAR-3 and the transmembrane protein E-cadherin/HMR-1. Intestinal cells break symmetry as PAR-3 and HMR-1 recruit apical determinants into punctate "local polarity complexes" (LPCs) at homotypic contacts. LPCs undergo an HMR-1-based migration to a common midline, thereby establishing tissue-wide polarity. Thus, symmetry breaking results from PAR-3-dependent intracellular polarization coupled to HMR-1-based tissue-level communication, which occurs through a non-adhesive signaling role for HMR-1. Differential lifetimes between homotypic and heterotypic cell contacts are created by neighbor exchanges and oriented divisions, patterning where LPCs perdure and thereby breaking symmetry. These cues offer a logical and likely conserved framework for how epithelia without obvious molecular asymmetries can polarize.
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Affiliation(s)
| | - Melissa A Pickett
- Department of Biology, Stanford University, Stanford, CA 94305, USA; Department of Biological Sciences, San José State University, San José, CA 95192, USA
| | - Jessica L Feldman
- Department of Biology, Stanford University, Stanford, CA 94305, USA.
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5
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Jain I, Rao M, Tran PT. Reliable and robust control of nucleus centering is contingent on nonequilibrium force patterns. iScience 2023; 26:106665. [PMID: 37182105 PMCID: PMC10173738 DOI: 10.1016/j.isci.2023.106665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 02/23/2023] [Accepted: 04/09/2023] [Indexed: 05/16/2023] Open
Abstract
Cell centers their division apparatus to ensure symmetric cell division, a challenging task when the governing dynamics is stochastic. Using fission yeast, we show that the patterning of nonequilibrium polymerization forces of microtubule (MT) bundles controls the precise localization of spindle pole body (SPB), and hence the division septum, at the onset of mitosis. We define two cellular objectives, reliability, the mean SPB position relative to the geometric center, and robustness, the variance of the SPB position, which are sensitive to genetic perturbations that change cell length, MT bundle number/orientation, and MT dynamics. We show that simultaneous control of reliability and robustness is required to minimize septum positioning error achieved by the wild type (WT). A stochastic model for the MT-based nucleus centering, with parameters measured directly or estimated using Bayesian inference, recapitulates the maximum fidelity of WT. Using this, we perform a sensitivity analysis of the parameters that control nuclear centering.
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Affiliation(s)
- Ishutesh Jain
- Institut Curie, PSL Universite, Sorbonne Universite, CNRS UMR 144, 75005 Paris, France
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences - TIFR, Bangalore 560065, India
| | - Madan Rao
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences - TIFR, Bangalore 560065, India
- Corresponding author
| | - Phong T. Tran
- Institut Curie, PSL Universite, Sorbonne Universite, CNRS UMR 144, 75005 Paris, France
- Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
- Corresponding author
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6
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Lamba A, Zernicka-Goetz M. The role of polarization and early heterogeneities in the mammalian first cell fate decision. Curr Top Dev Biol 2023; 154:169-196. [PMID: 37100517 DOI: 10.1016/bs.ctdb.2023.02.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/28/2023]
Abstract
The first cell fate decision is the process by which cells of an embryo take on distinct lineage identities for the first time, representing the beginning of patterning during development. In mammals, this process separates an embryonic inner cell mass lineage (future new organism) from an extra-embryonic trophectoderm lineage (future placenta), and in the mouse, this is classically attributed to the consequences of apical-basal polarity. The mouse embryo acquires this polarity at the 8-cell stage, indicated by cap-like protein domains on the apical surface of each cell; those cells which retain polarity over subsequent divisions are specified as trophectoderm, and the rest as inner cell mass. Recent research has advanced our knowledge of this process - this review will discuss mechanisms behind the establishment of polarity and distribution of the apical domain, different factors affecting the first cell fate decision including heterogeneities between cells of the very early embryo, and the conservation of developmental mechanisms across species, including human.
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Affiliation(s)
- Adiyant Lamba
- Mammalian Embryo and Stem Cell Group, Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom
| | - Magdalena Zernicka-Goetz
- Mammalian Embryo and Stem Cell Group, Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, United Kingdom; Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, United States.
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7
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Change of motifs in C. elegans reveals developmental principle of neural network. Biochem Biophys Res Commun 2022; 624:112-119. [PMID: 35940123 DOI: 10.1016/j.bbrc.2022.07.108] [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: 07/24/2022] [Accepted: 07/28/2022] [Indexed: 11/23/2022]
Abstract
Revealing the organizing principles of developing neural networks is a difficult but significant task in neuroscience. As a creature with a rather compact and well-studied neural network, C. elegans is an ideal subject for neuroscience study. However, the researches on its developing neural network remain challenging. The changes in specific properties of neural network across development may uncover part of its principles. Motif is a typical structure property that can be well applied to various complex networks. Here, we study the motif changes in C. elegans neural network across development. By counting the occurrence number of all three-node subgraph motif structures in its neural network at different stages of C. elegans development, along with those in corresponding random networks, we determine which of these structures are motifs for C. elegans, finding out the regular changes of motifs during its development. Combined with the potential function of these subgraph motifs and synaptic information, we gain insight into the organizing principle of neural network during development, which may increase our understanding of neuroscience and inspire the construction of artificial neural network.
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8
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Kimura K, Motegi F. Fluid flow dynamics in cellular patterning. Semin Cell Dev Biol 2021; 120:3-9. [PMID: 34274213 DOI: 10.1016/j.semcdb.2021.07.004] [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: 02/28/2021] [Revised: 06/24/2021] [Accepted: 07/01/2021] [Indexed: 10/20/2022]
Abstract
The development of complex forms of multicellular organisms depends on the spatial arrangement of cellular architecture and functions. The interior design of the cell is patterned by spatially biased distributions of molecules and biochemical reactions in the cytoplasm and/or on the plasma membrane. In recent years, a dynamic change in the cytoplasmic fluid flow has emerged as a key physical process of driving long-range transport of molecules to particular destinations within the cell. Here, recent experimental advances in the understanding of the generation of the various types of cytoplasmic flows and contributions to intracellular patterning are reviewed with a particular focus on feedback mechanisms between the mechanical properties of fluid flow and biochemical signaling during animal cell polarization.
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Affiliation(s)
- Kenji Kimura
- School of Science and Technology, Kwansei Gakuin University, Japan.
| | - Fumio Motegi
- Instiute for Genetic Medicine, Hokkaido University, Japan; Temasek Lifesciences Laboratory, Singapore; Mechanobiology Institute, National University of Singapore, Singapore; Department of Biological Sciences, National University of Singapore, Singapore.
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9
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CYK-1/Formin activation in cortical RhoA signaling centers promotes organismal left-right symmetry breaking. Proc Natl Acad Sci U S A 2021; 118:2021814118. [PMID: 33972425 PMCID: PMC8157923 DOI: 10.1073/pnas.2021814118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Proper left-right symmetry breaking is essential for animal development, and in many cases, this process is actomyosin-dependent. In Caenorhabditis elegans embryos active torque generation in the actomyosin layer promotes left-right symmetry breaking by driving chiral counterrotating cortical flows. While both Formins and Myosins have been implicated in left-right symmetry breaking and both can rotate actin filaments in vitro, it remains unclear whether active torques in the actomyosin cortex are generated by Formins, Myosins, or both. We combined the strength of C. elegans genetics with quantitative imaging and thin film, chiral active fluid theory to show that, while Non-Muscle Myosin II activity drives cortical actomyosin flows, it is permissive for chiral counterrotation and dispensable for chiral symmetry breaking of cortical flows. Instead, we find that CYK-1/Formin activation in RhoA foci is instructive for chiral counterrotation and promotes in-plane, active torque generation in the actomyosin cortex. Notably, we observe that artificially generated large active RhoA patches undergo rotations with consistent handedness in a CYK-1/Formin-dependent manner. Altogether, we conclude that CYK-1/Formin-dependent active torque generation facilitates chiral symmetry breaking of actomyosin flows and drives organismal left-right symmetry breaking in the nematode worm.
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10
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Collinet C, Lecuit T. Programmed and self-organized flow of information during morphogenesis. Nat Rev Mol Cell Biol 2021; 22:245-265. [PMID: 33483696 DOI: 10.1038/s41580-020-00318-6] [Citation(s) in RCA: 116] [Impact Index Per Article: 38.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/13/2020] [Indexed: 11/09/2022]
Abstract
How the shape of embryos and organs emerges during development is a fundamental question that has fascinated scientists for centuries. Tissue dynamics arise from a small set of cell behaviours, including shape changes, cell contact remodelling, cell migration, cell division and cell extrusion. These behaviours require control over cell mechanics, namely active stresses associated with protrusive, contractile and adhesive forces, and hydrostatic pressure, as well as material properties of cells that dictate how cells respond to active stresses. In this Review, we address how cell mechanics and the associated cell behaviours are robustly organized in space and time during tissue morphogenesis. We first outline how not only gene expression and the resulting biochemical cues, but also mechanics and geometry act as sources of morphogenetic information to ultimately define the time and length scales of the cell behaviours driving morphogenesis. Next, we present two idealized modes of how this information flows - how it is read out and translated into a biological effect - during morphogenesis. The first, akin to a programme, follows deterministic rules and is hierarchical. The second follows the principles of self-organization, which rests on statistical rules characterizing the system's composition and configuration, local interactions and feedback. We discuss the contribution of these two modes to the mechanisms of four very general classes of tissue deformation, namely tissue folding and invagination, tissue flow and extension, tissue hollowing and, finally, tissue branching. Overall, we suggest a conceptual framework for understanding morphogenetic information that encapsulates genetics and biochemistry as well as mechanics and geometry as information modules, and the interplay of deterministic and self-organized mechanisms of their deployment, thereby diverging considerably from the traditional notion that shape is fully encoded and determined by genes.
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Affiliation(s)
- Claudio Collinet
- Aix-Marseille Université & CNRS, IBDM - UMR7288 & Turing Centre for Living Systems, Campus de Luminy Case 907, Marseille, France
| | - Thomas Lecuit
- Aix-Marseille Université & CNRS, IBDM - UMR7288 & Turing Centre for Living Systems, Campus de Luminy Case 907, Marseille, France. .,Collège de France, Paris, France.
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11
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Salinas-Saavedra M, Martindale MQ. Par protein localization during the early development of Mnemiopsis leidyi suggests different modes of epithelial organization in the metazoa. eLife 2020; 9:54927. [PMID: 32716297 PMCID: PMC7441587 DOI: 10.7554/elife.54927] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 07/23/2020] [Indexed: 02/07/2023] Open
Abstract
In bilaterians and cnidarians, epithelial cell-polarity is regulated by the interactions between Par proteins, Wnt/PCP signaling pathway, and cell-cell adhesion. Par proteins are highly conserved across Metazoa, including ctenophores. But strikingly, ctenophore genomes lack components of the Wnt/PCP pathway and cell-cell adhesion complexes raising the question if ctenophore cells are polarized by mechanisms involving Par proteins. Here, by using immunohistochemistry and live-cell imaging of specific mRNAs, we describe for the first time the subcellular localization of selected Par proteins in blastomeres and epithelial cells during the embryogenesis of the ctenophore Mnemiopsis leidyi. We show that these proteins distribute differently compared to what has been described for other animals, even though they segregate in a host-specific fashion when expressed in cnidarian embryos. This differential localization might be related to the emergence of different junctional complexes during metazoan evolution.
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Affiliation(s)
- Miguel Salinas-Saavedra
- The Whitney Laboratory for Marine Bioscience, and the Department of Biology, University of Florida, St. Augustine, United States
| | - Mark Q Martindale
- The Whitney Laboratory for Marine Bioscience, and the Department of Biology, University of Florida, St. Augustine, United States
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12
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Centrosome Aurora A gradient ensures single polarity axis in C. elegans embryos. Biochem Soc Trans 2020; 48:1243-1253. [PMID: 32597472 DOI: 10.1042/bst20200298] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Revised: 05/25/2020] [Accepted: 06/08/2020] [Indexed: 01/31/2023]
Abstract
Cellular asymmetries are vital for generating cell fate diversity during development and in stem cells. In the newly fertilized Caenorhabditis elegans embryo, centrosomes are responsible for polarity establishment, i.e. anterior-posterior body axis formation. The signal for polarity originates from the centrosomes and is transmitted to the cell cortex, where it disassembles the actomyosin network. This event leads to symmetry breaking and the establishment of distinct domains of evolutionarily conserved PAR proteins. However, the identity of an essential component that localizes to the centrosomes and promotes symmetry breaking was unknown. Recent work has uncovered that the loss of Aurora A kinase (AIR-1 in C. elegans and hereafter referred to as Aurora A) in the one-cell embryo disrupts stereotypical actomyosin-based cortical flows that occur at the time of polarity establishment. This misregulation of actomyosin flow dynamics results in the occurrence of two polarity axes. Notably, the role of Aurora A in ensuring a single polarity axis is independent of its well-established function in centrosome maturation. The mechanism by which Aurora A directs symmetry breaking is likely through direct regulation of Rho-dependent contractility. In this mini-review, we will discuss the unconventional role of Aurora A kinase in polarity establishment in C. elegans embryos and propose a refined model of centrosome-dependent symmetry breaking.
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13
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Kapoor S, Kotak S. Centrosome Aurora A regulates RhoGEF ECT-2 localisation and ensures a single PAR-2 polarity axis in C. elegans embryos. Development 2019; 146:dev174565. [PMID: 31636075 PMCID: PMC7115938 DOI: 10.1242/dev.174565] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Accepted: 10/14/2019] [Indexed: 12/25/2022]
Abstract
Proper establishment of cell polarity is essential for development. In the one-cell C. elegans embryo, a centrosome-localised signal provides spatial information for polarity establishment. It is hypothesised that this signal causes local inhibition of the cortical actomyosin network, and breaks symmetry to direct partitioning of the PAR proteins. However, the molecular nature of the centrosomal signal that triggers cortical anisotropy in the actomyosin network to promote polarity establishment remains elusive. Here, we discover that depletion of Aurora A kinase (AIR-1 in C. elegans) causes pronounced cortical contractions on the embryo surface, and this creates more than one PAR-2 polarity axis. This function of AIR-1 appears to be independent of its role in microtubule nucleation. Importantly, upon AIR-1 depletion, centrosome positioning becomes dispensable in dictating the PAR-2 axis. Moreover, we uncovered that a Rho GEF, ECT-2, acts downstream of AIR-1 in regulating contractility and PAR-2 localisation, and, notably, AIR-1 depletion influences ECT-2 cortical localisation. Overall, this study provides a novel insight into how an evolutionarily conserved centrosome Aurora A kinase inhibits promiscuous PAR-2 domain formation to ensure singularity in the polarity establishment axis.
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Affiliation(s)
- Sukriti Kapoor
- Department of Microbiology and Cell Biology (MCB), Indian Institute of Science, Bangalore 560012, India
| | - Sachin Kotak
- Department of Microbiology and Cell Biology (MCB), Indian Institute of Science, Bangalore 560012, India
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14
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Gross P, Kumar KV, Goehring NW, Bois JS, Hoege C, Jülicher F, Grill SW. Guiding self-organized pattern formation in cell polarity establishment. NATURE PHYSICS 2019; 15:293-300. [PMID: 31327978 PMCID: PMC6640039 DOI: 10.1038/s41567-018-0358-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 10/23/2018] [Indexed: 05/25/2023]
Abstract
Spontaneous pattern formation in Turing systems relies on feedback. Patterns in cells and tissues however often do not form spontaneously, but are under control of upstream pathways that provide molecular guiding cues. The relationship between guiding cues and feedback in controlled biological pattern formation remains unclear. We explored this relationship during cell polarity establishment in the one-cell-stage C. elegans embryo. We quantified the strength of two feedback systems that operate during polarity establishment, feedback between polarity proteins and the actomyosin cortex, and mutual antagonism amongst polarity proteins. We characterized how these feedback systems are modulated by guiding cues from the centrosome. By coupling a mass-conserved Turing-like reaction-diffusion system for polarity proteins to an active gel description of the actomyosin cortex, we reveal a transition point beyond which feedback ensures self-organized polarization even when cues are removed. Notably, the baton is passed from a guide-dominated to a feedback-dominated regime significantly beyond this transition point, which ensures robustness. Together, this reveals a general criterion for controlling biological pattern forming systems: feedback remains subcritical to avoid unstable behaviour, and molecular guiding cues drive the system beyond a transition point for pattern formation.
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Affiliation(s)
- Peter Gross
- BIOTEC, TU Dresden, Tatzberg 47/49, 01307, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics,
Pfotenhauerstrasse 108, 01307 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems,
Nöthnitzer Strasse 38, 01187 Dresden, Germany
| | - K. Vijay Kumar
- Max Planck Institute for the Physics of Complex Systems,
Nöthnitzer Strasse 38, 01187 Dresden, Germany
- International Centre for Theoretical Sciences, Tata Institute of
Fundamental Research, Bengaluru 560089, India
| | - Nathan W. Goehring
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT,
UK
- Medical Research Council Laboratory for Molecular Cell Biology,
Gower Street, University College London, London WC1E 6BT, UK
| | - Justin S. Bois
- California Institute of Technology, 1200 E California Blvd,
Pasadena, CA 91125, USA
| | - Carsten Hoege
- Max Planck Institute of Molecular Cell Biology and Genetics,
Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Frank Jülicher
- Max Planck Institute for the Physics of Complex Systems,
Nöthnitzer Strasse 38, 01187 Dresden, Germany
| | - Stephan W. Grill
- BIOTEC, TU Dresden, Tatzberg 47/49, 01307, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics,
Pfotenhauerstrasse 108, 01307 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems,
Nöthnitzer Strasse 38, 01187 Dresden, Germany
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15
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Zhang Y, Dong J. Cell polarity: compassing cell division and differentiation in plants. CURRENT OPINION IN PLANT BIOLOGY 2018; 45:127-135. [PMID: 29957569 PMCID: PMC7183757 DOI: 10.1016/j.pbi.2018.06.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2018] [Revised: 06/05/2018] [Accepted: 06/12/2018] [Indexed: 05/18/2023]
Abstract
Protein polarization underlies directional cell growth, cell morphogenesis, cell division, fate specification and differentiation in plant development. Analysis of in vivo protein dynamics reveals differential mobility of polarized proteins in plant cells, which may arise from lateral diffusion, local protein-protein interactions, and is restricted by protein-membrane-cell wall connections. The asymmetric protein dynamics may provide a mechanism for the regulation of asymmetric cell division and cell differentiation. In light of recent evidence for preprophase band (PPB)-independent mechanisms for orienting division planes, polarity proteins and their dynamics might provide regulation on the PPB at the cell cortex to directly influence phragmoplast positioning or alternatively, impinge on cytoplasmic microtubule-organizing centers (MTOCs) for spindle alignment. Differentiation of specialized cell types is often associated with the spatial regulation of cell wall architecture. Here we discuss the mechanisms of polarized signaling underlying regional cell wall biosynthesis, degradation, and modification during the differentiation of root endodermal cells and leaf epidermal guard cells.
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Affiliation(s)
- Ying Zhang
- Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Juan Dong
- Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA; Department of Plant Biology, Rutgers, The State University of New Jersey, Piscataway, NJ 08901, USA.
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16
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Kim EJY, Korotkevich E, Hiiragi T. Coordination of Cell Polarity, Mechanics and Fate in Tissue Self-organization. Trends Cell Biol 2018; 28:541-550. [DOI: 10.1016/j.tcb.2018.02.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 02/20/2018] [Accepted: 02/20/2018] [Indexed: 02/06/2023]
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17
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Tan TH, Malik-Garbi M, Abu-Shah E, Li J, Sharma A, MacKintosh FC, Keren K, Schmidt CF, Fakhri N. Self-organized stress patterns drive state transitions in actin cortices. SCIENCE ADVANCES 2018; 4:eaar2847. [PMID: 29881775 PMCID: PMC5990313 DOI: 10.1126/sciadv.aar2847] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2017] [Accepted: 04/27/2018] [Indexed: 05/22/2023]
Abstract
Biological functions rely on ordered structures and intricately controlled collective dynamics. This order in living systems is typically established and sustained by continuous dissipation of energy. The emergence of collective patterns of motion is unique to nonequilibrium systems and is a manifestation of dynamic steady states. Mechanical resilience of animal cells is largely controlled by the actomyosin cortex. The cortex provides stability but is, at the same time, highly adaptable due to rapid turnover of its components. Dynamic functions involve regulated transitions between different steady states of the cortex. We find that model actomyosin cortices, constructed to maintain turnover, self-organize into distinct nonequilibrium steady states when we vary cross-link density. The feedback between actin network structure and organization of stress-generating myosin motors defines the symmetries of the dynamic steady states. A marginally cross-linked state displays divergence-free long-range flow patterns. Higher cross-link density causes structural symmetry breaking, resulting in a stationary converging flow pattern. We track the flow patterns in the model actomyosin cortices using fluorescent single-walled carbon nanotubes as novel probes. The self-organization of stress patterns we have observed in a model system can have direct implications for biological functions.
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Affiliation(s)
- Tzer Han Tan
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Maya Malik-Garbi
- Department of Physics, Technion—Israel Institute of Technology, Haifa, Israel
| | - Enas Abu-Shah
- Department of Physics, Technion—Israel Institute of Technology, Haifa, Israel
- Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa, Israel
| | - Junang Li
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Abhinav Sharma
- Department of Physics and Astronomy, Vrije Universiteit, Amsterdam, Netherlands
- Third Institute of Physics—Biophysics, University of Göttingen, Göttingen, Germany
| | - Fred C. MacKintosh
- Department of Physics and Astronomy, Vrije Universiteit, Amsterdam, Netherlands
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, TX 77005, USA
- Center for Theoretical Biophysics, Rice University, Houston, TX 77005, USA
| | - Kinneret Keren
- Department of Physics, Technion—Israel Institute of Technology, Haifa, Israel
- Russell Berrie Nanotechnology Institute, Technion—Israel Institute of Technology, Haifa, Israel
- Network Biology Research Laboratories, Technion—Israel Institute of Technology, Haifa, Israel
- Corresponding author. (K.K.); (C.F.S.); (N.F.)
| | - Christoph F. Schmidt
- Third Institute of Physics—Biophysics, University of Göttingen, Göttingen, Germany
- German Center for Cardiovascular Research (DZHK), Göttingen, Germany
- Department of Physics, Duke University, Durham, NC 27708, USA
- Corresponding author. (K.K.); (C.F.S.); (N.F.)
| | - Nikta Fakhri
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Corresponding author. (K.K.); (C.F.S.); (N.F.)
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18
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Sugioka K, Fielmich LE, Mizumoto K, Bowerman B, van den Heuvel S, Kimura A, Sawa H. Tumor suppressor APC is an attenuator of spindle-pulling forces during C. elegans asymmetric cell division. Proc Natl Acad Sci U S A 2018; 115:E954-E963. [PMID: 29348204 PMCID: PMC5798331 DOI: 10.1073/pnas.1712052115] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The adenomatous polyposis coli (APC) tumor suppressor has dual functions in Wnt/β-catenin signaling and accurate chromosome segregation and is frequently mutated in colorectal cancers. Although APC contributes to proper cell division, the underlying mechanisms remain poorly understood. Here we show that Caenorhabditis elegans APR-1/APC is an attenuator of the pulling forces acting on the mitotic spindle. During asymmetric cell division of the C. elegans zygote, a LIN-5/NuMA protein complex localizes dynein to the cell cortex to generate pulling forces on astral microtubules that position the mitotic spindle. We found that APR-1 localizes to the anterior cell cortex in a Par-aPKC polarity-dependent manner and suppresses anterior centrosome movements. Our combined cell biological and mathematical analyses support the conclusion that cortical APR-1 reduces force generation by stabilizing microtubule plus-ends at the cell cortex. Furthermore, APR-1 functions in coordination with LIN-5 phosphorylation to attenuate spindle-pulling forces. Our results document a physical basis for the attenuation of spindle-pulling force, which may be generally used in asymmetric cell division and, when disrupted, potentially contributes to division defects in cancer.
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Affiliation(s)
- Kenji Sugioka
- Multicellular Organization Laboratory, National Institute of Genetics, 411-8540 Mishima, Japan
- RIKEN Center for Developmental Biology, Chuo-ku, 650-0047 Kobe, Japan
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
| | - Lars-Eric Fielmich
- Developmental Biology, Biology Department, Science 4 Life, Utrecht University, 3584 CH Utrecht, The Netherlands
| | - Kota Mizumoto
- RIKEN Center for Developmental Biology, Chuo-ku, 650-0047 Kobe, Japan
| | - Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
| | - Sander van den Heuvel
- Developmental Biology, Biology Department, Science 4 Life, Utrecht University, 3584 CH Utrecht, The Netherlands;
| | - Akatsuki Kimura
- Cell Architecture Laboratory, National Institute of Genetics, 411-8540 Mishima, Japan;
- Department of Genetics, School of Life Science, Sokendai, 411-8540 Mishima, Japan
| | - Hitoshi Sawa
- Multicellular Organization Laboratory, National Institute of Genetics, 411-8540 Mishima, Japan;
- RIKEN Center for Developmental Biology, Chuo-ku, 650-0047 Kobe, Japan
- Department of Genetics, School of Life Science, Sokendai, 411-8540 Mishima, Japan
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19
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Roubinet C, Tsankova A, Pham TT, Monnard A, Caussinus E, Affolter M, Cabernard C. Spatio-temporally separated cortical flows and spindle geometry establish physical asymmetry in fly neural stem cells. Nat Commun 2017; 8:1383. [PMID: 29123099 PMCID: PMC5680339 DOI: 10.1038/s41467-017-01391-w] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Accepted: 09/04/2017] [Indexed: 01/09/2023] Open
Abstract
Asymmetric cell division, creating sibling cells with distinct developmental potentials, can be manifested in sibling cell size asymmetry. This form of physical asymmetry occurs in several metazoan cells, but the underlying mechanisms and function are incompletely understood. Here we use Drosophila neural stem cells to elucidate the mechanisms involved in physical asymmetry establishment. We show that Myosin relocalizes to the cleavage furrow via two distinct cortical Myosin flows: at anaphase onset, a polarity induced, basally directed Myosin flow clears Myosin from the apical cortex. Subsequently, mitotic spindle cues establish a Myosin gradient at the lateral neuroblast cortex, necessary to trigger an apically directed flow, removing Actomyosin from the basal cortex. On the basis of the data presented here, we propose that spatiotemporally controlled Myosin flows in conjunction with spindle positioning and spindle asymmetry are key determinants for correct cleavage furrow placement and cortical expansion, thereby establishing physical asymmetry.
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Affiliation(s)
- Chantal Roubinet
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
- MRC Laboratory for Molecular Cell Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Anna Tsankova
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
- Streuli Pharma AG, Bahnhofstrasse 7, CH-8730, Uznach, Switzerland
| | - Tri Thanh Pham
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
- Department of Biology, University of Washington, 24 Kincaid Hall, Seattle, WA, 98195, USA
| | - Arnaud Monnard
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
- Department of Biology, University of Washington, 24 Kincaid Hall, Seattle, WA, 98195, USA
| | - Emmanuel Caussinus
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland
| | - Markus Affolter
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland
| | - Clemens Cabernard
- Biozentrum, University of Basel, Klingelbergstrasse 50-70, CH-4056, Basel, Switzerland.
- Department of Biology, University of Washington, 24 Kincaid Hall, Seattle, WA, 98195, USA.
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20
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Campanale JP, Sun TY, Montell DJ. Development and dynamics of cell polarity at a glance. J Cell Sci 2017; 130:1201-1207. [PMID: 28365593 DOI: 10.1242/jcs.188599] [Citation(s) in RCA: 125] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Cells exhibit morphological and molecular asymmetries that are broadly categorized as cell polarity. The cell polarity established in early embryos prefigures the macroscopic anatomical asymmetries characteristic of adult animals. For example, eggs and early embryos have polarized distributions of RNAs and proteins that generate global anterior/posterior and dorsal/ventral axes. The molecular programs that polarize embryos are subsequently reused in multiple contexts. Epithelial cells require apical/basal polarity to establish their barrier function. Migrating cells polarize in the direction of movement, creating distinct leading and trailing structures. Asymmetrically dividing stem cells partition different molecules between themselves and their daughter cells. Cell polarity can develop de novo, be maintained through rounds of cell division and be dynamically remodeled. In this Cell Science at a Glance review and poster, we describe molecular asymmetries that underlie cell polarity in several cellular contexts. We highlight multiple developmental systems that first establish cell/developmental polarity, and then maintain it. Our poster showcases repeated use of the Par, Scribble and Crumbs polarity complexes, which drive the development of cell polarity in many cell types and organisms. We then briefly discuss the diverse and dynamic changes in cell polarity that occur during cell migration, asymmetric cell division and in planar polarized tissues.
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Affiliation(s)
- Joseph P Campanale
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Thomas Y Sun
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
| | - Denise J Montell
- Department of Molecular, Cellular and Developmental Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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21
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Nuñez IN, Matute TF, Del Valle ID, Kan A, Choksi A, Endy D, Haseloff J, Rudge TJ, Federici F. Artificial Symmetry-Breaking for Morphogenetic Engineering Bacterial Colonies. ACS Synth Biol 2017; 6:256-265. [PMID: 27794593 DOI: 10.1021/acssynbio.6b00149] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Morphogenetic engineering is an emerging field that explores the design and implementation of self-organized patterns, morphologies, and architectures in systems composed of multiple agents such as cells and swarm robots. Synthetic biology, on the other hand, aims to develop tools and formalisms that increase reproducibility, tractability, and efficiency in the engineering of biological systems. We seek to apply synthetic biology approaches to the engineering of morphologies in multicellular systems. Here, we describe the engineering of two mechanisms, symmetry-breaking and domain-specific cell regulation, as elementary functions for the prototyping of morphogenetic instructions in bacterial colonies. The former represents an artificial patterning mechanism based on plasmid segregation while the latter plays the role of artificial cell differentiation by spatial colocalization of ubiquitous and segregated components. This separation of patterning from actuation facilitates the design-build-test-improve engineering cycle. We created computational modules for CellModeller representing these basic functions and used it to guide the design process and explore the design space in silico. We applied these tools to encode spatially structured functions such as metabolic complementation, RNAPT7 gene expression, and CRISPRi/Cas9 regulation. Finally, as a proof of concept, we used CRISPRi/Cas technology to regulate cell growth by controlling methionine synthesis. These mechanisms start from single cells enabling the study of morphogenetic principles and the engineering of novel population scale structures from the bottom up.
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Affiliation(s)
- Isaac N. Nuñez
- Escuela
de Ingeniería, Pontificia Universidad Católica de Chile, 7820436, Santiago, Chile
- Fondo
de Desarrollo de Areas Prioritarias Center for Genome Regulation,
Millennium Nucleus Center for Plant Systems and Synthetic Biology, Pontificia Universidad Católica de Chile, 7820436, Santiago, Chile
| | - Tamara F. Matute
- Escuela
de Ingeniería, Pontificia Universidad Católica de Chile, 7820436, Santiago, Chile
- Fondo
de Desarrollo de Areas Prioritarias Center for Genome Regulation,
Millennium Nucleus Center for Plant Systems and Synthetic Biology, Pontificia Universidad Católica de Chile, 7820436, Santiago, Chile
| | - Ilenne D. Del Valle
- Departamento
de Genética Molecular y Microbiología, Facultad de Ciencias
Biológicas, Pontificia Universidad Católica de Chile, 8331150, Santiago, Chile
| | - Anton Kan
- Department
of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, United Kingdom
| | - Atri Choksi
- Department
of Bioengineering, Stanford University, Stanford, California 94305, United States,
| | - Drew Endy
- Department
of Bioengineering, Stanford University, Stanford, California 94305, United States,
| | - Jim Haseloff
- Department
of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, United Kingdom
| | - Timothy J. Rudge
- Escuela
de Ingeniería, Pontificia Universidad Católica de Chile, 7820436, Santiago, Chile
| | - Fernan Federici
- Departamento
de Genética Molecular y Microbiología, Facultad de Ciencias
Biológicas, Pontificia Universidad Católica de Chile, 8331150, Santiago, Chile
- Department
of Plant Sciences, University of Cambridge, Downing Street, Cambridge, CB2 3EA, United Kingdom
- Fondo
de Desarrollo de Areas Prioritarias Center for Genome Regulation,
Millennium Nucleus Center for Plant Systems and Synthetic Biology, Pontificia Universidad Católica de Chile, 7820436, Santiago, Chile
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22
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Sugioka K, Hamill DR, Lowry JB, McNeely ME, Enrick M, Richter AC, Kiebler LE, Priess JR, Bowerman B. Centriolar SAS-7 acts upstream of SPD-2 to regulate centriole assembly and pericentriolar material formation. eLife 2017; 6. [PMID: 28092264 PMCID: PMC5342823 DOI: 10.7554/elife.20353] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 01/15/2017] [Indexed: 12/30/2022] Open
Abstract
The centriole/basal body is a eukaryotic organelle that plays essential roles in cell division and signaling. Among five known core centriole proteins, SPD-2/Cep192 is the first recruited to the site of daughter centriole formation and regulates the centriolar localization of the other components in C. elegans and in humans. However, the molecular basis for SPD-2 centriolar localization remains unknown. Here, we describe a new centriole component, the coiled-coil protein SAS-7, as a regulator of centriole duplication, assembly and elongation. Intriguingly, our genetic data suggest that SAS-7 is required for daughter centrioles to become competent for duplication, and for mother centrioles to maintain this competence. We also show that SAS-7 binds SPD-2 and regulates SPD-2 centriolar recruitment, while SAS-7 centriolar localization is SPD-2-independent. Furthermore, pericentriolar material (PCM) formation is abnormal in sas-7 mutants, and the PCM-dependent induction of cell polarity that defines the anterior-posterior body axis frequently fails. We conclude that SAS-7 functions at the earliest step in centriole duplication yet identified and plays important roles in the orchestration of centriole and PCM assembly. DOI:http://dx.doi.org/10.7554/eLife.20353.001
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Affiliation(s)
- Kenji Sugioka
- Institute of Molecular Biology, University of Oregon, Eugene, United States
| | - Danielle R Hamill
- Department of Zoology, Ohio Wesleyan University, Delaware, United States
| | - Joshua B Lowry
- Institute of Molecular Biology, University of Oregon, Eugene, United States
| | - Marie E McNeely
- Department of Zoology, Ohio Wesleyan University, Delaware, United States
| | - Molly Enrick
- Department of Zoology, Ohio Wesleyan University, Delaware, United States
| | - Alyssa C Richter
- Department of Zoology, Ohio Wesleyan University, Delaware, United States
| | - Lauren E Kiebler
- Department of Zoology, Ohio Wesleyan University, Delaware, United States
| | - James R Priess
- Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, United States.,Molecular and Cellular Biology Program, University of Washington, Seattle, United States.,Department of Biology, University of Washington, Seattle, United States
| | - Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene, United States
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23
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Lam AK, Phillips BT. Wnt Signaling Polarizes C. elegans Asymmetric Cell Divisions During Development. Results Probl Cell Differ 2017; 61:83-114. [PMID: 28409301 PMCID: PMC6057142 DOI: 10.1007/978-3-319-53150-2_4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Asymmetric cell division is a common mode of cell differentiation during the invariant lineage of the nematode, C. elegans. Beginning at the four-cell stage, and continuing throughout embryogenesis and larval development, mother cells are polarized by Wnt ligands, causing an asymmetric inheritance of key members of a Wnt/β-catenin signal transduction pathway termed the Wnt/β-catenin asymmetry pathway. The resulting daughter cells are distinct at birth with one daughter cell activating Wnt target gene expression via β-catenin activation of TCF, while the other daughter displays transcriptional repression of these target genes. Here, we seek to review the body of evidence underlying a unified model for Wnt-driven asymmetric cell division in C. elegans, identify global themes that occur during asymmetric cell division, as well as highlight tissue-specific variations. We also discuss outstanding questions that remain unanswered regarding this intriguing mode of asymmetric cell division.
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Affiliation(s)
- Arielle Koonyee Lam
- Interdisciplinary Graduate Program in Molecular and Cellular Biology, University of Iowa, Iowa City, IA, USA
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24
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Wu HY, Nazockdast E, Shelley MJ, Needleman DJ. Forces positioning the mitotic spindle: Theories, and now experiments. Bioessays 2016; 39. [PMID: 28026040 DOI: 10.1002/bies.201600212] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The position of the spindle determines the position of the cleavage plane, and is thus crucial for cell division. Although spindle positioning has been extensively studied, the underlying forces ultimately responsible for moving the spindle remain poorly understood. A recent pioneering study by Garzon-Coral et al. uses magnetic tweezers to perform the first direct measurements of the forces involved in positioning the mitotic spindle. Combining this with molecular perturbations and geometrical effects, they use their data to argue that the forces that keep the spindle in its proper position for cell division arise from astral microtubules growing and pushing against the cell's cortex. Here, we review these ground-breaking experiments, the various biomechanical models for spindle positioning that they seek to differentiate, and discuss new questions raised by these measurements.
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Affiliation(s)
- Hai-Yin Wu
- Department of Physics, Harvard University, Cambridge, MA, USA
- Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, MA, USA
| | - Ehssan Nazockdast
- Center for Computational Biology, Simons Foundation, New York, NY, USA
| | - Michael J Shelley
- Center for Computational Biology, Simons Foundation, New York, NY, USA
- Courant Institute of Mathematical Sciences, New York University, New York, NY, USA
| | - Daniel J Needleman
- Faculty of Arts and Sciences Center for Systems Biology, Harvard University, Cambridge, MA, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, USA
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25
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Reymann AC, Staniscia F, Erzberger A, Salbreux G, Grill SW. Cortical flow aligns actin filaments to form a furrow. eLife 2016; 5:e17807. [PMID: 27719759 PMCID: PMC5117871 DOI: 10.7554/elife.17807] [Citation(s) in RCA: 103] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 10/07/2016] [Indexed: 01/27/2023] Open
Abstract
Cytokinesis in eukaryotic cells is often accompanied by actomyosin cortical flow. Over 30 years ago, Borisy and White proposed that cortical flow converging upon the cell equator compresses the actomyosin network to mechanically align actin filaments. However, actin filaments also align via search-and-capture, and to what extent compression by flow or active alignment drive furrow formation remains unclear. Here, we quantify the dynamical organization of actin filaments at the onset of ring assembly in the C. elegans zygote, and provide a framework for determining emergent actomyosin material parameters by the use of active nematic gel theory. We characterize flow-alignment coupling, and verify at a quantitative level that compression by flow drives ring formation. Finally, we find that active alignment enhances but is not required for ring formation. Our work characterizes the physical mechanisms of actomyosin ring formation and highlights the role of flow as a central organizer of actomyosin network architecture.
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Affiliation(s)
- Anne-Cecile Reymann
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
| | - Fabio Staniscia
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
| | - Anna Erzberger
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
| | - Guillaume Salbreux
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
- The Francis Crick Institute, London, United Kingdom
| | - Stephan W Grill
- Biotechnology Center, Technische Universität Dresden, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
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26
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Li F, Subramanian K, Chen M, Tyson JJ, Cao Y. A stochastic spatiotemporal model of a response-regulator network in the Caulobacter crescentus cell cycle. Phys Biol 2016; 13:035007. [PMID: 27345750 DOI: 10.1088/1478-3975/13/3/035007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The asymmetric cell division cycle in Caulobacter crescentus is controlled by an elaborate molecular mechanism governing the production, activation and spatial localization of a host of interacting proteins. In previous work, we proposed a deterministic mathematical model for the spatiotemporal dynamics of six major regulatory proteins. In this paper, we study a stochastic version of the model, which takes into account molecular fluctuations of these regulatory proteins in space and time during early stages of the cell cycle of wild-type Caulobacter cells. We test the stochastic model with regard to experimental observations of increased variability of cycle time in cells depleted of the divJ gene product. The deterministic model predicts that overexpression of the divK gene blocks cell cycle progression in the stalked stage; however, stochastic simulations suggest that a small fraction of the mutants cells do complete the cell cycle normally.
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Affiliation(s)
- Fei Li
- Departments of Computer Science, Virginia Tech, Blacksburg, VA 24061,USA
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27
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Abstract
Gametogenesis in animal oocytes reduces the diploid genome content of germline precursors to a haploid state in gametes by discarding ¾ of the duplicated chromosomes through a sequence of two meiotic cell divisions called meiosis I and II. The assembly of the microtubule-based spindle structure that mediates this reduction in genome content remains poorly understood compared to our knowledge of mitotic spindle assembly and function. In this review, we consider the diversity of oocyte meiotic spindle assembly and structure across animal phylogeny, review recent advances in our understanding of how animal oocytes assemble spindles in the absence of the centriole-based microtubule-organizing centers that dominate mitotic spindle assembly, and discuss different models for how chromosomes are captured and moved to achieve chromosome segregation during oocyte meiotic cell division.
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Affiliation(s)
- Aaron F Severson
- Department of Biological, Geological, and Environmental Sciences, Center for Gene Regulation in Health and Disease, Cleveland State University, Cleveland, Ohio, USA
| | - George von Dassow
- Oregon Institute of Marine Biology, University of Oregon, Charleston, Oregon, USA
| | - Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, USA.
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28
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Dynamic Opposition of Clustered Proteins Stabilizes Cortical Polarity in the C. elegans Zygote. Dev Cell 2016; 35:131-42. [PMID: 26460948 DOI: 10.1016/j.devcel.2015.09.006] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 08/05/2015] [Accepted: 09/10/2015] [Indexed: 12/13/2022]
Abstract
Dynamic maintenance of cell polarity is essential for development and physiology. Here we combine experiments and modeling to elucidate mechanisms that maintain cortical polarity in the C. elegans zygote. We show that polarity is dynamically stabilized by two coupled cross-inhibitory feedback loops: one involves the oligomeric scaffold PAR-3 and the kinase PAR-1, and the other involves CDC-42 and its putative GAP CHIN-1. PAR-3 and CDC-42 are both required locally to recruit PAR-6/PKC-3, which inhibits PAR-1 (shown previously) and inhibits local growth/accumulation of CHIN-1 clusters. Conversely, PAR-1 inhibits local accumulation of PAR-3 oligomers, while CHIN-1 inhibits CDC-42 (shown previously), such that either PAR-1 or CHIN-1 can prevent recruitment of PAR-6/PKC-3, but loss of both causes complete loss of polarity. Ultrasensitive dependence of CHIN-1 cluster growth on PAR-6/PKC-3 endows this core circuit with bistable dynamics, while transport of CHIN-1 clusters by cortical flow can stabilize the AP boundary against diffusive spread of PAR-6/PKC-3.
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29
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Barr J, Yakovlev KV, Shidlovskii Y, Schedl P. Establishing and maintaining cell polarity with mRNA localization in Drosophila. Bioessays 2016; 38:244-53. [PMID: 26773560 DOI: 10.1002/bies.201500088] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
How cell polarity is established and maintained is an important question in diverse biological contexts. Molecular mechanisms used to localize polarity proteins to distinct domains are likely context-dependent and provide a feedback loop in order to maintain polarity. One such mechanism is the localized translation of mRNAs encoding polarity proteins, which will be the focus of this review and may play a more important role in the establishment and maintenance of polarity than is currently known. Localized translation of mRNAs encoding polarity proteins can be used to establish polarity in response to an external signal, and to maintain polarity by local production of polarity determinants. The importance of this mechanism is illustrated by recent findings, including orb2-dependent localized translation of aPKC mRNA at the apical end of elongating spermatid tails in the Drosophila testis, and the apical localization of stardust A mRNA in Drosophila follicle and embryonic epithelia.
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Affiliation(s)
- Justinn Barr
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA
| | - Konstantin V Yakovlev
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology RAS, Moscow, Russia.,A.V. Zhirmunsky Institute of Marine Biology, FEB RAS Laboratory of Cytotechnology, Vladivostok, Russia
| | - Yulii Shidlovskii
- Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology RAS, Moscow, Russia
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, Princeton, NJ, USA.,Laboratory of Gene Expression Regulation in Development, Institute of Gene Biology RAS, Moscow, Russia
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30
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Mao Q, Lecuit T. Mechanochemical Interplay Drives Polarization in Cellular and Developmental Systems. Curr Top Dev Biol 2016; 116:633-57. [DOI: 10.1016/bs.ctdb.2015.11.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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Ajduk A, Zernicka-Goetz M. Polarity and cell division orientation in the cleavage embryo: from worm to human. Mol Hum Reprod 2015; 22:691-703. [PMID: 26660321 PMCID: PMC5062000 DOI: 10.1093/molehr/gav068] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 11/25/2015] [Indexed: 01/01/2023] Open
Abstract
Cleavage is a period after fertilization, when a 1-cell embryo starts developing into a multicellular organism. Due to a series of mitotic divisions, the large volume of a fertilized egg is divided into numerous smaller, nucleated cells—blastomeres. Embryos of different phyla divide according to different patterns, but molecular mechanism of these early divisions remains surprisingly conserved. In the present paper, we describe how polarity cues, cytoskeleton and cell-to-cell communication interact with each other to regulate orientation of the early embryonic division planes in model animals such as Caenorhabditis elegans, Drosophila and mouse. We focus particularly on the Par pathway and the actin-driven cytoplasmic flows that accompany it. We also describe a unique interplay between Par proteins and the Hippo pathway in cleavage mammalian embryos. Moreover, we discuss the potential meaning of polarity, cytoplasmic dynamics and cell-to-cell communication as quality biomarkers of human embryos.
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Affiliation(s)
- Anna Ajduk
- Department of Embryology, Faculty of Biology, University of Warsaw, Miecznikowa 1, 02-096 Warsaw, Poland
| | - Magdalena Zernicka-Goetz
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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Oriented cell division: new roles in guiding skin wound repair and regeneration. Biosci Rep 2015; 35:BSR20150225. [PMID: 26582817 PMCID: PMC4708010 DOI: 10.1042/bsr20150225] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2015] [Accepted: 11/12/2015] [Indexed: 01/14/2023] Open
Abstract
Tissue morphogenesis depends on precise regulation and timely co-ordination of cell division and also on the control of the direction of cell division. Establishment of polarity division axis, correct alignment of the mitotic spindle, segregation of fate determinants equally or unequally between daughter cells, are essential for the realization of oriented cell division. Furthermore, oriented cell division is regulated by intrinsic cues, extrinsic cues and other cues, such as cell geometry and polarity. However, dysregulation of cell division orientation could lead to abnormal tissue development and function. In the present study, we review recent studies on the molecular mechanism of cell division orientation and explain their new roles in skin repair and regeneration.
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Subramanian K, Paul MR, Tyson JJ. Dynamical Localization of DivL and PleC in the Asymmetric Division Cycle of Caulobacter crescentus: A Theoretical Investigation of Alternative Models. PLoS Comput Biol 2015; 11:e1004348. [PMID: 26186202 PMCID: PMC4505887 DOI: 10.1371/journal.pcbi.1004348] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Accepted: 05/20/2015] [Indexed: 11/18/2022] Open
Abstract
Cell-fate asymmetry in the predivisional cell of Caulobacter crescentus requires that the regulatory protein DivL localizes to the new pole of the cell where it up-regulates CckA kinase, resulting in a gradient of CtrA~P across the cell. In the preceding stage of the cell cycle (the "stalked" cell), DivL is localized uniformly along the cell membrane and maintained in an inactive form by DivK~P. It is unclear how DivL overcomes inhibition by DivK~P in the predivisional cell simply by changing its location to the new pole. It has been suggested that co-localization of DivL with PleC phosphatase at the new pole is essential to DivL's activity there. However, there are contrasting views on whether the bifunctional enzyme, PleC, acts as a kinase or phosphatase at the new pole. To explore these ambiguities, we formulated a mathematical model of the spatiotemporal distributions of DivL, PleC and associated proteins (DivJ, DivK, CckA, and CtrA) during the asymmetric division cycle of a Caulobacter cell. By varying localization profiles of DivL and PleC in our model, we show how the physiologically observed spatial distributions of these proteins are essential for the transition from a stalked cell to a predivisional cell. Our simulations suggest that PleC is a kinase in predivisional cells, and that, by sequestering DivK~P, the kinase form of PleC enables DivL to be reactivated at the new pole. Hence, co-localization of PleC kinase and DivL is essential to establishing cellular asymmetry. Our simulations reproduce the experimentally observed spatial distribution and phosphorylation status of CtrA in wild-type and mutant cells. Based on the model, we explore novel combinations of mutant alleles, making predictions that can be tested experimentally.
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Affiliation(s)
- Kartik Subramanian
- Graduate Program in Genetics, Bioinformatics and Computational Biology, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
| | - Mark R. Paul
- Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
| | - John J. Tyson
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
- Virginia Bioinformatics Institute, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States of America
- * E-mail:
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Abstract
Actomyosin-mediated contractility is a highly conserved mechanism for generating mechanical stress in animal cells and underlies muscle contraction, cell migration, cell division and tissue morphogenesis. Whereas actomyosin-mediated contractility in striated muscle is well understood, the regulation of such contractility in non-muscle and smooth muscle cells is less certain. Our increased understanding of the mechanics of actomyosin arrays that lack sarcomeric organization has revealed novel modes of regulation and force transmission. This work also provides an example of how diverse mechanical behaviours at cellular scales can arise from common molecular components, underscoring the need for experiments and theories to bridge the molecular to cellular length scales.
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Ho VWS, Wong MK, An X, Guan D, Shao J, Ng HCK, Ren X, He K, Liao J, Ang Y, Chen L, Huang X, Yan B, Xia Y, Chan LLH, Chow KL, Yan H, Zhao Z. Systems-level quantification of division timing reveals a common genetic architecture controlling asynchrony and fate asymmetry. Mol Syst Biol 2015; 11:814. [PMID: 26063786 PMCID: PMC4501849 DOI: 10.15252/msb.20145857] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Coordination of cell division timing is crucial for proper cell fate specification and tissue growth. However, the differential regulation of cell division timing across or within cell types during metazoan development remains poorly understood. To elucidate the systems-level genetic architecture coordinating division timing, we performed a high-content screening for genes whose depletion produced a significant reduction in the asynchrony of division between sister cells (ADS) compared to that of wild-type during Caenorhabditis elegans embryogenesis. We quantified division timing using 3D time-lapse imaging followed by computer-aided lineage analysis. A total of 822 genes were selected for perturbation based on their conservation and known roles in development. Surprisingly, we find that cell fate determinants are not only essential for establishing fate asymmetry, but also are imperative for setting the ADS regardless of cellular context, indicating a common genetic architecture used by both cellular processes. The fate determinants demonstrate either coupled or separate regulation between the two processes. The temporal coordination appears to facilitate cell migration during fate specification or tissue growth. Our quantitative dataset with cellular resolution provides a resource for future analyses of the genetic control of spatial and temporal coordination during metazoan development.
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Affiliation(s)
- Vincy Wing Sze Ho
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Ming-Kin Wong
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Xiaomeng An
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Daogang Guan
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Jiaofang Shao
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Hon Chun Kaoru Ng
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Xiaoliang Ren
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Kan He
- Department of Biology, Hong Kong Baptist University, Hong Kong, China Center for Stem Cell and Translational Medicine, School of Life Sciences Anhui University, Hefei, China
| | - Jinyue Liao
- Division of Life Science and Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Yingjin Ang
- Division of Life Science and Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Long Chen
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - Xiaotai Huang
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - Bin Yan
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Yiji Xia
- Department of Biology, Hong Kong Baptist University, Hong Kong, China
| | - Leanne Lai Hang Chan
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - King Lau Chow
- Division of Life Science and Division of Biomedical Engineering, The Hong Kong University of Science and Technology, Hong Kong, China
| | - Hong Yan
- Department of Electronic Engineering, City University of Hong Kong, Hong Kong, China
| | - Zhongying Zhao
- Department of Biology, Hong Kong Baptist University, Hong Kong, China State Key Laboratory of Environmental and Biological Analysis, Hong Kong Baptist University, Hong Kong, China
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Salinas-Saavedra M, Stephenson TQ, Dunn CW, Martindale MQ. Par system components are asymmetrically localized in ectodermal epithelia, but not during early development in the sea anemone Nematostella vectensis. EvoDevo 2015; 6:20. [PMID: 26101582 PMCID: PMC4476184 DOI: 10.1186/s13227-015-0014-6] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 03/12/2015] [Indexed: 11/10/2022] Open
Abstract
Background The evolutionary origins of cell polarity in metazoan embryos are unclear. In most bilaterian animals, embryonic and cell polarity are set up during embryogenesis with the same molecules being utilized to regulate tissue polarity at different life stages. Atypical protein kinase C (aPKC), lethal giant larvae (Lgl), and Partitioning-defective (Par) proteins are conserved components of cellular polarization, and their role in establishing embryonic asymmetry and tissue polarity have been widely studied in model bilaterian groups. However, the deployment and role of these proteins in animals outside Bilateria has not been studied. We address this by characterizing the localization of different components of the Par system during early development of the sea anemone Nematostella vectensis, a member of the clade Cnidaria, the sister group to bilaterian animals. Results Immunostaining using specific N. vectensis antibodies and the overexpression of mRNA-reporter constructs show that components of the N. vectensis Par system (NvPar-1, NvPar-3, NvPar-6, NvaPKC, and NvLgl) distribute throughout the microtubule cytoskeleton of eggs and early embryos without clear polarization along any embryonic axis. However, they become asymmetrically distributed at later stages, when the embryo forms an ectodermal epithelial layer. NvLgl and NvPar-1 localize in the basolateral cortex, and NvaPKC, NvPar-6, and NvPar-3 at the apical zone of the cell in a manner seen in bilaterian animals. Conclusions The cnidarian N. vectensis exhibits clear polarity at all stages of early embryonic development, which appears to be established independent of the Par system reported in many bilaterian embryos. However, in N. vectensis, using multiple immunohistochemical and fluorescently labeled markers in vivo, components of this system are deployed to organize epithelial cell polarity at later stages of development. This suggests that Par system proteins were co-opted to organize early embryonic cell polarity at the base of the Bilateria and that, therefore, different molecular mechanisms operate in early cnidarian embryogenesis. Electronic supplementary material The online version of this article (doi:10.1186/s13227-015-0014-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Miguel Salinas-Saavedra
- The Whitney Laboratory for Marine Bioscience, University of Florida, 9505 N, Ocean Shore Blvd, St. Augustine, FL 32080-8610 USA
| | - Thomas Q Stephenson
- The Whitney Laboratory for Marine Bioscience, University of Florida, 9505 N, Ocean Shore Blvd, St. Augustine, FL 32080-8610 USA
| | - Casey W Dunn
- Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912 USA
| | - Mark Q Martindale
- The Whitney Laboratory for Marine Bioscience, University of Florida, 9505 N, Ocean Shore Blvd, St. Augustine, FL 32080-8610 USA
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37
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Stam S, Alberts J, Gardel ML, Munro E. Isoforms Confer Characteristic Force Generation and Mechanosensation by Myosin II Filaments. Biophys J 2015; 108:1997-2006. [PMID: 25902439 PMCID: PMC4407263 DOI: 10.1016/j.bpj.2015.03.030] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 01/27/2015] [Accepted: 03/02/2015] [Indexed: 12/21/2022] Open
Abstract
Myosin II isoforms with varying mechanochemistry and filament size interact with filamentous actin (F-actin) arrays to generate contractile forces in muscle and nonmuscle cells. How myosin II force production is shaped by isoform-specific motor properties and environmental stiffness remains poorly understood. Here, we used computer simulations to analyze force production by an ensemble of myosin motors against an elastically tethered actin filament. We found that force output depends on two timescales: the duration of F-actin attachment, which varies sharply with the ensemble size, motor duty ratio, and external load; and the time to build force, which scales with the ensemble stall force, gliding speed, and environmental stiffness. Although force-dependent kinetics were not required to sense changes in stiffness, the myosin catch bond produced positive feedback between the attachment time and force to trigger switch-like transitions from transient attachments, generating small forces, to high-force-generating runs. Using parameters representative of skeletal muscle myosin, nonmuscle myosin IIB, and nonmuscle myosin IIA revealed three distinct regimes of behavior, respectively: 1) large assemblies of fast, low-duty ratio motors rapidly build stable forces over a large range of environmental stiffness; 2) ensembles of slow, high-duty ratio motors serve as high-affinity cross-links with force buildup times that exceed physiological timescales; and 3) small assemblies of low-duty ratio motors operating at intermediate speeds are poised to respond sharply to changes in mechanical context-at low force or stiffness, they serve as low-affinity cross-links, but they can transition to force production via the positive-feedback mechanism described above. Together, these results reveal how myosin isoform properties may be tuned to produce force and respond to mechanical cues in their environment.
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Affiliation(s)
- Samantha Stam
- Biophysical Sciences Graduate Program, University of Washington, Friday Harbor, Washington; Institute for Biophysical Dynamics, University of Washington, Friday Harbor, Washington
| | - Jon Alberts
- Center for Cell Dynamics, University of Washington, Friday Harbor, Washington
| | - Margaret L Gardel
- Institute for Biophysical Dynamics, University of Washington, Friday Harbor, Washington; Physics Department, University of Chicago, Chicago, Illinois; James Franck Institute, University of Chicago, Chicago, Illinois; Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois.
| | - Edwin Munro
- Institute for Biophysical Dynamics, University of Washington, Friday Harbor, Washington; Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois.
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38
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Griffin EE. Cytoplasmic localization and asymmetric division in the early embryo of Caenorhabditis elegans. WILEY INTERDISCIPLINARY REVIEWS-DEVELOPMENTAL BIOLOGY 2015; 4:267-82. [PMID: 25764455 DOI: 10.1002/wdev.177] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Revised: 12/16/2014] [Accepted: 01/04/2015] [Indexed: 11/09/2022]
Abstract
During the initial cleavages of the Caenorhabditis elegans embryo, a series of rapid and invariant asymmetric cell divisions pattern the fate, size, and position of four somatic blastomeres and a single germline blastomere. These asymmetric divisions are orchestrated by a collection of maternally deposited factors that are initially symmetrically distributed in the newly fertilized embryo. Maturation of the sperm-derived centrosome in the posterior cytoplasm breaks this symmetry by triggering a dramatic and highly stereotyped partitioning of these maternal factors. A network of conserved cell polarity regulators, the PAR proteins, form distinct anterior and posterior domains at the cell cortex. From these domains, the PAR proteins direct the segregation of somatic and germline factors into opposing regions of the cytoplasm such that, upon cell division, they are preferentially inherited by the somatic blastomere or the germline blastomere, respectively. The segregation of these factors is controlled, at least in part, by a series of reaction-diffusion mechanisms that are asymmetrically deployed along the anterior/posterior axis. The characterization of these mechanisms has important implications for our understanding of how cells are polarized and how spatial organization is generated in the cytoplasm. For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Erik E Griffin
- Department of Biological Sciences, Dartmouth College, Hanover, NH, USA
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39
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Abu Shah E, Malik-Garbi M, Keren K. Reconstitution of cortical actin networks within water-in-oil emulsions. Methods Cell Biol 2015; 128:287-301. [DOI: 10.1016/bs.mcb.2015.01.011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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40
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Keikhaee MR, Nash EB, O'Rourke SM, Bowerman B. A semi-dominant mutation in the general splicing factor SF3a66 causes anterior-posterior axis reversal in one-cell stage C. elegans embryos. PLoS One 2014; 9:e106484. [PMID: 25188372 PMCID: PMC4154684 DOI: 10.1371/journal.pone.0106484] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2014] [Accepted: 07/31/2014] [Indexed: 11/19/2022] Open
Abstract
Establishment of anterior-posterior polarity in one-cell stage Caenorhabditis elegans embryos depends in part on astral microtubules. As the zygote enters mitosis, these microtubules promote the establishment of a posterior pole by binding to and protecting a cytoplasmic pool of the posterior polarity protein PAR-2 from phosphorylation by the cortically localized anterior polarity protein PKC-3. Prior to activation of the sperm aster, the oocyte Meiosis I and II spindles assemble and function, usually at the future anterior pole, but these meiotic spindle microtubules fail to establish posterior polarity through PAR-2. Here we show that a semi-dominant mutation in the general splicing factor SF3a66 can lead to a reversed axis of AP polarity that depends on PAR-2 and possibly on close proximity of oocyte meiotic spindles with the cell cortex. One possible explanation is that reduced levels of PKC-3, due to a general splicing defect, can result in axis reversal due to a failure to prevent oocyte meiotic spindle microtubules from interfering with AP axis formation.
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Affiliation(s)
- Mohammad R. Keikhaee
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Eric B. Nash
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Sean M. O'Rourke
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
| | - Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon, United States of America
- * E-mail:
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41
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Landmann F, Foster JM, Michalski ML, Slatko BE, Sullivan W. Co-evolution between an endosymbiont and its nematode host: Wolbachia asymmetric posterior localization and AP polarity establishment. PLoS Negl Trop Dis 2014; 8:e3096. [PMID: 25165813 PMCID: PMC4148215 DOI: 10.1371/journal.pntd.0003096] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 07/03/2014] [Indexed: 01/07/2023] Open
Abstract
While bacterial symbionts influence a variety of host cellular responses throughout development, there are no documented instances in which symbionts influence early embryogenesis. Here we demonstrate that Wolbachia, an obligate endosymbiont of the parasitic filarial nematodes, is required for proper anterior-posterior polarity establishment in the filarial nematode B. malayi. Characterization of pre- and post-fertilization events in B. malayi reveals that, unlike C. elegans, the centrosomes are maternally derived and produce a cortical-based microtubule organizing center prior to fertilization. We establish that Wolbachia rely on these cortical microtubules and dynein to concentrate at the posterior cortex. Wolbachia also rely on PAR-1 and PAR-3 polarity cues for normal concentration at the posterior cortex. Finally, we demonstrate that Wolbachia depletion results in distinct anterior-posterior polarity defects. These results provide a striking example of endosymbiont-host co-evolution operating on the core initial developmental event of axis determination. Filarial nematodes are responsible for a number of neglected tropical diseases. The vast majority of these human parasites harbor the bacterial endosymbiont Wolbachia. Wolbachia are essential for filarial nematode survival and reproduction, and thus are a promising anti-filarial drug target. Understanding the molecular and cellular basis of Wolbachia-nematode interactions will facilitate the development of a new class of drugs that specifically disrupt these interactions. Here we focus on Wolbachia segregation patterns and interactions with the host cytoskeleton during early embryogenesis. Our studies indicate that centrosomes are maternally inherited in filarial nematodes resulting in a posterior microtubule-organizing center of maternal origin, unique to filarial nematodes. This microtubule-organizing center facilitates the concentration of Wolbachia at the posterior pole. We find that the microtubule motor dynein is required for the proper posterior Wolbachia localization. In addition, we demonstrate that Wolbachia rely on polarity signals in the egg for their preferential localization at the posterior pole. Conversely, Wolbachia are required for normal embryonic axis determination and Wolbachia removal leads to distinct anterior-posterior embryonic polarity defects. To our knowledge, this is the first example of a bacterial endosymbiont required for normal host embryogenesis.
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Affiliation(s)
- Frederic Landmann
- Department of Molecular, Cell and Developmental Biology, Sinsheimer Labs, University of California, Santa Cruz, California, United States of America
- Centre de Recherche de Biochimie Macromoléculaire, CNRS, Montpellier, France
- * E-mail:
| | - Jeremy M. Foster
- Molecular Parasitology, New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Michelle L. Michalski
- Department of Biology and Microbiology, University of Wisconsin Oshkosh, Oshkosh, Wisconsin, United States of America
| | - Barton E. Slatko
- Molecular Parasitology, New England Biolabs, Ipswich, Massachusetts, United States of America
| | - William Sullivan
- Department of Molecular, Cell and Developmental Biology, Sinsheimer Labs, University of California, Santa Cruz, California, United States of America
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Blum M, Feistel K, Thumberger T, Schweickert A. The evolution and conservation of left-right patterning mechanisms. Development 2014; 141:1603-13. [PMID: 24715452 DOI: 10.1242/dev.100560] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Morphological asymmetry is a common feature of animal body plans, from shell coiling in snails to organ placement in humans. The signaling protein Nodal is key for determining this laterality. Many vertebrates, including humans, use cilia for breaking symmetry during embryonic development: rotating cilia produce a leftward flow of extracellular fluids that induces the asymmetric expression of Nodal. By contrast, Nodal asymmetry can be induced flow-independently in invertebrates. Here, we ask when and why flow evolved. We propose that flow was present at the base of the deuterostomes and that it is required to maintain organ asymmetry in otherwise perfectly bilaterally symmetrical vertebrates.
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Affiliation(s)
- Martin Blum
- Institute of Zoology, University of Hohenheim, 70593 Stuttgart, Germany
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43
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Xu S, Tyagi S, Schedl P. Spermatid cyst polarization in Drosophila depends upon apkc and the CPEB family translational regulator orb2. PLoS Genet 2014; 10:e1004380. [PMID: 24830287 PMCID: PMC4022466 DOI: 10.1371/journal.pgen.1004380] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 03/28/2014] [Indexed: 12/22/2022] Open
Abstract
Mature Drosophila sperm are highly polarized cells—on one side is a nearly 2 mm long flagellar tail that comprises most of the cell, while on the other is the sperm head, which carries the gamete's genetic information. The polarization of the sperm cells commences after meiosis is complete and the 64-cell spermatid cyst begins the process of differentiation. The spermatid nuclei cluster to one side of the cyst, while the flagellar axonemes grows from the other. The elongating spermatid bundles are also polarized with respect to the main axis of the testis; the sperm heads are always oriented basally, while the growing tails extend apically. This orientation within the testes is important for transferring the mature sperm into the seminal vesicles. We show here that orienting cyst polarization with respect to the main axis of the testis depends upon atypical Protein Kinase C (aPKC), a factor implicated in polarity decisions in many different biological contexts. When apkc activity is compromised in the male germline, the direction of cyst polarization within this organ is randomized. Significantly, the mechanisms used to spatially restrict apkc activity to the apical side of the spermatid cyst are different from the canonical cross-regulatory interactions between this kinase and other cell polarity proteins that normally orchestrate polarization. We show that the asymmetric accumulation of aPKC protein in the cyst depends on an mRNA localization pathway that is regulated by the Drosophila CPEB protein Orb2. orb2 is required to properly localize and activate the translation of apkc mRNAs in polarizing spermatid cysts. We also show that orb2 functions not only in orienting cyst polarization with respect to the apical-basal axis of the testis, but also in the process of polarization itself. One of the orb2 targets in this process is its own mRNA. Moreover, the proper execution of this orb2 autoregulatory pathway depends upon apkc. After completion of meiosis, the 64 cells in the spermatid cyst begin differentiating into sperm. Sperm are highly polarized cells and a critical step in their differentiation is spermatid cyst polarization. Spermatids are also polarized within the testis, with the heads of the elongating spermatids located basally, while the tails extend apically. We show that aPKC accumulates preferentially on the apical side of the cyst during polarization and is required to correctly orient cyst polarization with respect to the apical-basal axis of the testis. Unexpectedly, aPKC activity is spatially restricted by a mechanism that depends upon the CPEB family translational regulator orb2. orb2 is required to asymmetrically localize and activate the translation of apkc mRNAs during spermatid differentiation. In addition to correctly orienting the direction of cyst polarization, orb2 is required for the process of polarization itself. One of the orb2 regulatory targets in this process is its own mRNA, and this autoregulatory activity depends, in turn, upon apkc.
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Affiliation(s)
- Shuwa Xu
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Sanjay Tyagi
- Public Health Research Institute, New Jersey Medical School, Rutgers University, Newark, New Jersey, United States of America
| | - Paul Schedl
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- Institute of Gene Biology, RAS, Moscow, Russia
- * E-mail:
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44
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Abstract
The actin cortex plays a pivotal role in cell division, in generating and maintaining cell polarity and in motility. In all these contexts, the cortical network has to break symmetry to generate polar cytoskeletal dynamics. Despite extensive research, the mechanisms responsible for regulating cortical dynamics in vivo and inducing symmetry breaking are still unclear. Here we introduce a reconstituted system that self-organizes into dynamic actin cortices at the inner interface of water-in-oil emulsions. This artificial system undergoes spontaneous symmetry breaking, driven by myosin-induced cortical actin flows, which appears remarkably similar to the initial polarization of the embryo in many species. Our in vitro model system recapitulates the rich dynamics of actin cortices in vivo, revealing the basic biophysical and biochemical requirements for cortex formation and symmetry breaking. Moreover, this synthetic system paves the way for further exploration of artificial cells towards the realization of minimal model systems that can move and divide. DOI:http://dx.doi.org/10.7554/eLife.01433.001 Cells are extremely complex because they have to perform a vast number of processes. However, this also makes it difficult for researchers to figure out how the individual parts of the cell work. There is interest, therefore, in developing simple artificial cells that can accurately mimic how specific parts of a cell behave. An important process for a cell is called polarization. This is where the contents of the cell arrange themselves in a way that is not symmetrical. Polarization is necessary for many cellular functions, and is particularly important during embryonic development where it helps to form the complex shape of the developing embryo. The cytoskeleton—a dynamic structure that supports the cell and enables it to move—is crucial for polarization. An important part of the cytoskeleton is the actin cortex. This is a thin active sheet made up of a network of tiny filaments of a protein called actin that assembles at the inner face of the cell membrane. Many aspects of the structure and behavior of the actin cortex are not understood. Abu Shah and Keren have now developed an artificial cell system using aqueous droplets surrounded by oil that can reproduce the behavior of actin cortices in real cells. An actin cortex forms upon the localization of specific nucleation factors at the inner surface of the droplets. The artificial cortices are capable of spontaneous symmetry breaking, similar to the initial polarization in embryonic cells during development. This symmetry breaking is driven by molecular motors called myosins and depends on the connectivity of the actin network in the cortex. Experiments on the artificial cells also rule out several other mechanisms that have been proposed to explain symmetry breaking. The work of Abu Shah and Keren represents a further step towards the goal of creating simple artificial cells that can move and divide. DOI:http://dx.doi.org/10.7554/eLife.01433.002
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Affiliation(s)
- Enas Abu Shah
- Department of Physics, Technion-Israel Institute of Technology, Haifa, Israel The Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, Israel
| | - Kinneret Keren
- Department of Physics, Technion-Israel Institute of Technology, Haifa, Israel The Russell Berrie Nanotechnology Institute, Technion-Israel Institute of Technology, Haifa, Israel Network Biology Research Laboratories, Technion-Israel Institute of Technology, Haifa, Israel
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45
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Abstract
High and low nuclear levels of the conserved transcriptional regulator β-catenin distinguish multiple sister cell fates to specify endoderm and mesoderm during early embryogenesis in a chordate embryo.
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Affiliation(s)
- Stephan Q Schneider
- Department of Genetics, Development and Cell Biology, 503 Science Hall II, Iowa State University, Ames, IA 50011, USA.
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46
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Beloussov LV. Morphogenesis can be driven by properly parametrised mechanical feedback. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2013; 36:132. [PMID: 24264054 DOI: 10.1140/epje/i2013-13132-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 06/23/2013] [Accepted: 10/15/2013] [Indexed: 06/02/2023]
Abstract
A fundamental problem of morphogenesis is whether it presents itself as a succession of links that are each driven by its own specific cause-effect relationship, or whether all of the links can be embraced by a common law that is possible to formulate in physical terms. We suggest that a common biophysical background for most, if not all, morphogenetic processes is based upon feedback between mechanical stresses (MS) that are imposed to a given part of a developing embryo by its other parts and MS that are actively generated within that part. The latter are directed toward hyper-restoration (restoration with an overshoot) of the initial MS values. We show that under mechanical constraints imposed by other parts, these tendencies drive forth development. To provide specificity for morphogenetic reactions, this feedback should be modulated by long-term parameters and/or initial conditions that are set up by genetic factors. The experimental and model data related to this concept are reviewed.
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Affiliation(s)
- L V Beloussov
- Laboratory of Developmental Biophysics, Faculty of Biology, Moscow State University, 119992, Moscow, Russia,
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47
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Brennan LD, Roland T, Morton DG, Fellman SM, Chung S, Soltani M, Kevek JW, McEuen PM, Kemphues KJ, Wang MD. Small molecule injection into single-cell C. elegans embryos via carbon-reinforced nanopipettes. PLoS One 2013; 8:e75712. [PMID: 24086620 PMCID: PMC3784451 DOI: 10.1371/journal.pone.0075712] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 08/16/2013] [Indexed: 11/19/2022] Open
Abstract
The introduction of chemical inhibitors into living cells at specific times in development is a useful method for investigating the roles of specific proteins or cytoskeletal components in developmental processes. Some embryos, such as those of Caenorhabditis elegans, however, possess a tough eggshell that makes introducing drugs and other molecules into embryonic cells challenging. We have developed a procedure using carbon-reinforced nanopipettes (CRNPs) to deliver molecules into C. elegans embryos with high temporal control. The use of CRNPs allows for cellular manipulation to occur just subsequent to meiosis II with minimal damage to the embryo. We have used our technique to replicate classical experiments using latrunculin A to inhibit microfilaments and assess its effects on early polarity establishment. Our injections of latrunculin A confirm the necessity of microfilaments in establishing anterior-posterior polarity at this early stage, even when microtubules remain intact. Further, we find that latrunculin A treatment does not prevent association of PAR-2 or PAR-6 with the cell cortex. Our experiments demonstrate the application of carbon-reinforced nanopipettes to the study of one temporally-confined developmental event. The use of CRNPs to introduce molecules into the embryo should be applicable to investigations at later developmental stages as well as other cells with tough outer coverings.
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Affiliation(s)
- Lucy D. Brennan
- Department of Physics - Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York, United States of America
| | - Thibault Roland
- Department of Physics - Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York, United States of America
- Howard Hughes Medical Institute, Cornell University, Ithaca, New York, United States of America
| | - Diane G. Morton
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Shanna M. Fellman
- Department of Physics - Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York, United States of America
- Howard Hughes Medical Institute, Cornell University, Ithaca, New York, United States of America
| | - SueYeon Chung
- Department of Physics - Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York, United States of America
- Howard Hughes Medical Institute, Cornell University, Ithaca, New York, United States of America
| | - Mohammad Soltani
- Department of Physics - Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York, United States of America
- Howard Hughes Medical Institute, Cornell University, Ithaca, New York, United States of America
| | - Joshua W. Kevek
- Department of Physics - Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York, United States of America
| | - Paul M. McEuen
- Department of Physics - Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York, United States of America
| | - Kenneth J. Kemphues
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
- * E-mail: (MDW); (KJK)
| | - Michelle D. Wang
- Department of Physics - Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York, United States of America
- Howard Hughes Medical Institute, Cornell University, Ithaca, New York, United States of America
- * E-mail: (MDW); (KJK)
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48
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Pettersson S, Forchheimer R, Larsson JÅ. Meta-Boolean models of asymmetric division patterns in the C. elegans intestinal lineage: Implications for the posterior boundary of intestinal twist. WORM 2013; 2:e23701. [PMID: 24058861 PMCID: PMC3670462 DOI: 10.4161/worm.23701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 01/14/2013] [Indexed: 11/24/2022]
Abstract
The intestine of Caenorhabditis elegans is derived from 20 cells that are organized into nine intestinal rings. During embryogenesis, three of the rings rotate approximately 90 degrees in a process known as intestinal twist. The underlying mechanisms for this morphological event are not fully known, but it has been demonstrated that both left-right and anterior-posterior asymmetry is required for intestinal twist to occur. We have recently presented a rule-based meta-Boolean tree model intended to describe complex lineages. In this report we apply this model to the E lineage of C. elegans, specifically targeting the asymmetric anterior-posterior division patterns within the lineage. The resulting model indicates that cells with the same factor concentration are located next to each other in the intestine regardless of lineage origin. In addition, the shift in factor concentrations coincides with the boundary for intestinal twist. When modeling lit-1 mutant data according to the same principle, the factor distributions in each cell are altered, yet the concurrence between the shift in concentration and intestinal twist remains. This pattern suggests that intestinal twist is controlled by a threshold mechanism. In the current paper we present the factor concentrations for all possible combinations of symmetric and asymmetric divisions in the E lineage and relate these to the potential threshold by studying existing data for wild-type and mutant embryos. Finally, we discuss how the resulting models can serve as a basis for experimental design in order to reveal the underlying mechanisms of intestinal twist.
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Affiliation(s)
- Sofia Pettersson
- Division of Information Coding; Department of Electrical Engineering; Linköping University; Linköping, Sweden
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49
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Abstract
Asymmetric cell division (ACD), a mechanism for cell-type diversification in both prokaryotes and eukaryotes, is accomplished through highly coordinated cell-fate segregation, genome partitioning, and cell division. Whereas important paradigms have arisen from the study of animal embryonic divisions, the strategies for choreographing the dynamic subprocesses are, in fact, highly varied. This review examines divergent mechanisms of ACD across different kingdoms. Examples discussed show that there is no obligatory hierarchy among the dynamic events and that asymmetry can emerge from each event, but cell polarization more often occurs as the initial instructive process for patterning ACD especially in the multicellular context.
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Affiliation(s)
- Rong Li
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA.
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50
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Abstract
Asymmetric cell division (ACD) produces two daughter cells with distinct fates or characteristics. Many adult stem cells use ACD as a means of maintaining stem cell number and thus tissue homeostasis. Here, we review recent progress on ACD, discussing conservation between stem and non-stem cell systems, molecular mechanisms, and the biological meaning of ACD.
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