1
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Chevalier L, Klingelschmitt F, Mousseron L, Minc N. Mechanical strategies supporting growth and size diversity in Filamentous Fungi. Mol Biol Cell 2024; 35:br17. [PMID: 39046771 DOI: 10.1091/mbc.e24-04-0171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/25/2024] Open
Abstract
The stereotypical tip growth of filamentous fungi supports their lifestyles and functions. It relies on the polarized remodeling and expansion of a protective elastic cell wall (CW) driven by large cytoplasmic turgor pressure. Remarkably, hyphal filament diameters and cell elongation rates can vary extensively among different fungi. To date, however, how fungal cell mechanics may be adapted to support these morphological diversities while ensuring surface integrity remains unknown. Here, we combined super-resolution imaging and deflation assays to measure local CW thickness, elasticity and turgor in a set of fungal species spread on the evolutionary tree that spans a large range in cell size and growth speeds. While CW elasticity exhibited dispersed values, presumably reflecting differences in CW composition, both thickness and turgor scaled in dose-dependence with cell diameter and growth speeds. Notably, larger cells exhibited thinner lateral CWs, and faster cells thinner apical CWs. Counterintuitively, turgor pressure was also inversely scaled with cell diameter and tip growth speed, challenging the idea that turgor is the primary factor dictating tip elongation rates. We propose that fast-growing cells with rapid CW turnover have evolved strategies based on a less turgid cytoplasm and thin walls to safeguard surface integrity and survival.
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Affiliation(s)
- Louis Chevalier
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
- Equipe Labellisée LIGUE Contre le Cancer, 75013 Paris, France
| | - Flora Klingelschmitt
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
- Equipe Labellisée LIGUE Contre le Cancer, 75013 Paris, France
| | - Ludovic Mousseron
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
- Equipe Labellisée LIGUE Contre le Cancer, 75013 Paris, France
| | - Nicolas Minc
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013 Paris, France
- Equipe Labellisée LIGUE Contre le Cancer, 75013 Paris, France
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2
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Ohairwe ME, Živanović BD, Rojas ER. A fitness landscape instability governs the morphological diversity of tip-growing cells. Cell Rep 2024; 43:113961. [PMID: 38531367 DOI: 10.1016/j.celrep.2024.113961] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 01/12/2024] [Accepted: 02/28/2024] [Indexed: 03/28/2024] Open
Abstract
Cellular morphology affects many aspects of cellular and organismal physiology. This makes it challenging to dissect the evolutionary basis for specific morphologies since various cellular functions may exert competing selective pressures on this trait, and the influence of these pressures will depend on the specific mechanisms of morphogenesis. In this light, we combined experiment and theory to investigate the complex basis for morphological diversity among tip-growing cells from across the tree of life. We discovered that an instability in the widespread mechanism of "inflationary" tip growth leads directly to a bifurcation in the common fitness landscape of tip-growing cells, which imposes a strict global constraint on their morphologies. This result rationalizes the morphology of an enormous diversity of important fungal, plant, protistan, and bacterial systems. More broadly, our study elucidates the principle that strong evolutionary constraints on complex traits, like biological form, may emerge from emergent instabilities within developmental systems.
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Affiliation(s)
- Maxim E Ohairwe
- Department of Biology, New York University, New York, NY 10003, USA
| | - Branka D Živanović
- Institute for Multidisciplinary Research, University of Belgrade, Belgrade, Serbia
| | - Enrique R Rojas
- Department of Biology, New York University, New York, NY 10003, USA.
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3
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Lemière J, Chang F. Quantifying turgor pressure in budding and fission yeasts based upon osmotic properties. Mol Biol Cell 2023; 34:ar133. [PMID: 37903220 PMCID: PMC10848946 DOI: 10.1091/mbc.e23-06-0215] [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: 06/07/2023] [Revised: 10/02/2023] [Accepted: 10/11/2023] [Indexed: 11/01/2023] Open
Abstract
Walled cells, such as plants, fungi, and bacteria cells, possess a high internal hydrostatic pressure, termed turgor pressure, that drives volume growth and contributes to cell shape determination. Rigorous measurement of turgor pressure, however, remains challenging, and reliable quantitative measurements, even in budding yeast are still lacking. Here, we present a simple and robust experimental approach to access turgor pressure in yeasts based upon the determination of isotonic concentration using protoplasts as osmometers. We propose three methods to identify the isotonic condition - three-dimensional cell volume, cytoplasmic fluorophore intensity, and mobility of a cytGEMs nano-rheology probe - that all yield consistent values. Our results provide turgor pressure estimates of 1.0 ± 0.1 MPa for Schizosaccharomyces pombe, 0.49 ± 0.01 MPa for Schizosaccharomyces japonicus, 0.5 ± 0.1 MPa for Saccharomyces cerevisiae W303a and 0.31 ± 0.03 MPa for Saccharomyces cerevisiae BY4741. Large differences in turgor pressure and nano-rheology measurements between the Saccharomyces cerevisiae strains demonstrate how fundamental biophysical parameters can vary even among wild-type strains of the same species. These side-by-side measurements of turgor pressure in multiple yeast species provide critical values for quantitative studies on cellular mechanics and comparative evolution.
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Affiliation(s)
- Joël Lemière
- Department of Cell and Tissue Biology, University of California, San Francisco, CA 94143
| | - Fred Chang
- Department of Cell and Tissue Biology, University of California, San Francisco, CA 94143
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4
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Lemière J, Chang F. Quantifying turgor pressure in budding and fission yeasts based upon osmotic properties. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.07.544129. [PMID: 37333400 PMCID: PMC10274794 DOI: 10.1101/2023.06.07.544129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Walled cells, such as plants, fungi, and bacteria cells, possess a high internal hydrostatic pressure, termed turgor pressure, that drives volume growth and contributes to cell shape determination. Rigorous measurement of turgor pressure, however, remains challenging, and reliable quantitative measurements, even in budding yeast are still lacking. Here, we present a simple and robust experimental approach to access turgor pressure in yeasts based upon the determination of isotonic concentration using protoplasts as osmometers. We propose three methods to identify the isotonic condition - 3D cell volume, cytoplasmic fluorophore intensity, and mobility of a cytGEMs nano-rheology probe - that all yield consistent values. Our results provide turgor pressure estimates of 1.0 ± 0.1 MPa for S. pombe, 0.49 ± 0.01 MPa for S. japonicus, 0.5 ± 0.1 MPa for S. cerevisiae W303a and 0.31 ± 0.03 MPa for S. cerevisiae BY4741. Large differences in turgor pressure and nano-rheology measurements between the S. cerevisiae strains demonstrate how fundamental biophysical parameters can vary even among wildtype strains of the same species. These side-by-side measurements of turgor pressure in multiple yeast species provide critical values for quantitative studies on cellular mechanics and comparative evolution.
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Affiliation(s)
- Joël Lemière
- Department of Cell and Tissue Biology, University of San Francisco, CA, USA
| | - Fred Chang
- Department of Cell and Tissue Biology, University of San Francisco, CA, USA
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5
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Awada Z, Nedjar B. On a finite strain modeling of growth in budding yeast. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2023; 39:e3710. [PMID: 37070287 DOI: 10.1002/cnm.3710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 01/05/2023] [Accepted: 04/02/2023] [Indexed: 06/07/2023]
Abstract
Cell's ability to proliferate constitutes one of the most defining features of life. The proliferation occurs through a succession of events; the cell cycle, whereby the cell grows and divides. In this paper, focus is made on the growth step and we deal specifically with Saccharomyces cerevisiae yeast that reproduces by budding. For this, we develop a theoretical model to predict the growth powered by the turgor pressure. This cell is herein considered as a thin-walled structure with almost axisymmetrical shape. Due to its soft nature, the large deformation range is a priori assumed through a finite growth modeling framework. The used kinematics is based on the multiplicative decomposition of the deformation gradient into an elastically reversible part and a growth part. Constitutive equations are proposed where use is made of hyperelasticity together with a local evolution equation, this latter to describe the way growth takes place. In particular, two essential parameters are involved: a stress-like threshold, and a characteristic time. The developed model is extended to a shell approach as well. In a finite element context, representative numerical simulations examining stress-dependent growth are given and a parametric study is conducted to show the sensitivity with respect to the above mentioned parameters. Finally, a suggestion for natural contractile ring modeling closes this study.
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Affiliation(s)
- Zeinab Awada
- MAST (MAterial and STructures), EMGCU (Expérimenation en Modélisation pour le Génic Civil et Urdain), Université Gustave Eiffel, Marne-la-Vallée cedex 2, France
| | - Boumediene Nedjar
- MAST (MAterial and STructures), EMGCU (Expérimenation en Modélisation pour le Génic Civil et Urdain), Université Gustave Eiffel, Marne-la-Vallée cedex 2, France
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6
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Garner RM, Molines AT, Theriot JA, Chang F. Vast heterogeneity in cytoplasmic diffusion rates revealed by nanorheology and Doppelgänger simulations. Biophys J 2023; 122:767-783. [PMID: 36739478 PMCID: PMC10027447 DOI: 10.1016/j.bpj.2023.01.040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 12/22/2022] [Accepted: 01/30/2023] [Indexed: 02/05/2023] Open
Abstract
The cytoplasm is a complex, crowded, actively driven environment whose biophysical characteristics modulate critical cellular processes such as cytoskeletal dynamics, phase separation, and stem cell fate. Little is known about the variance in these cytoplasmic properties. Here, we employed particle-tracking nanorheology on genetically encoded multimeric 40 nm nanoparticles (GEMs) to measure diffusion within the cytoplasm of individual fission yeast (Schizosaccharomyces pombe) cellscells. We found that the apparent diffusion coefficients of individual GEM particles varied over a 400-fold range, while the differences in average particle diffusivity among individual cells spanned a 10-fold range. To determine the origin of this heterogeneity, we developed a Doppelgänger simulation approach that uses stochastic simulations of GEM diffusion that replicate the experimental statistics on a particle-by-particle basis, such that each experimental track and cell had a one-to-one correspondence with their simulated counterpart. These simulations showed that the large intra- and inter-cellular variations in diffusivity could not be explained by experimental variability but could only be reproduced with stochastic models that assume a wide intra- and inter-cellular variation in cytoplasmic viscosity. The simulation combining intra- and inter-cellular variation in viscosity also predicted weak nonergodicity in GEM diffusion, consistent with the experimental data. To probe the origin of this variation, we found that the variance in GEM diffusivity was largely independent of factors such as temperature, the actin and microtubule cytoskeletons, cell-cyle stage, and spatial locations, but was magnified by hyperosmotic shocks. Taken together, our results provide a striking demonstration that the cytoplasm is not "well-mixed" but represents a highly heterogeneous environment in which subcellular components at the 40 nm size scale experience dramatically different effective viscosities within an individual cell, as well as in different cells in a genetically identical population. These findings carry significant implications for the origins and regulation of biological noise at cellular and subcellular levels.
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Affiliation(s)
- Rikki M Garner
- Biophysics Program, Stanford University School of Medicine, Stanford, California; Department of Biology and Howard Hughes Medical Institute, University of Washington, Seattle, Washington; Marine Biological Laboratory, Woods Hole, Massachusetts.
| | - Arthur T Molines
- Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California; Marine Biological Laboratory, Woods Hole, Massachusetts.
| | - Julie A Theriot
- Biophysics Program, Stanford University School of Medicine, Stanford, California; Department of Biology and Howard Hughes Medical Institute, University of Washington, Seattle, Washington; Marine Biological Laboratory, Woods Hole, Massachusetts
| | - Fred Chang
- Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, California; Marine Biological Laboratory, Woods Hole, Massachusetts
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7
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Cell wall dynamics stabilize tip growth in a filamentous fungus. PLoS Biol 2023; 21:e3001981. [PMID: 36649360 PMCID: PMC9882835 DOI: 10.1371/journal.pbio.3001981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 01/27/2023] [Accepted: 12/22/2022] [Indexed: 01/18/2023] Open
Abstract
Hyphal tip growth allows filamentous fungi to colonize space, reproduce, or infect. It features remarkable morphogenetic plasticity including unusually fast elongation rates, tip turning, branching, or bulging. These shape changes are all driven from the expansion of a protective cell wall (CW) secreted from apical pools of exocytic vesicles. How CW secretion, remodeling, and deformation are modulated in concert to support rapid tip growth and morphogenesis while ensuring surface integrity remains poorly understood. We implemented subresolution imaging to map the dynamics of CW thickness and secretory vesicles in Aspergillus nidulans. We found that tip growth is associated with balanced rates of CW secretion and expansion, which limit temporal fluctuations in CW thickness, elongation speed, and vesicle amount, to less than 10% to 20%. Affecting this balance through modulations of growth or trafficking yield to near-immediate changes in CW thickness, mechanics, and shape. We developed a model with mechanical feedback that accounts for steady states of hyphal growth as well as rapid adaptation of CW mechanics and vesicle recruitment to different perturbations. These data provide unprecedented details on how CW dynamics emerges from material secretion and expansion, to stabilize fungal tip growth as well as promote its morphogenetic plasticity.
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8
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Municio-Diaz C, Muller E, Drevensek S, Fruleux A, Lorenzetti E, Boudaoud A, Minc N. Mechanobiology of the cell wall – insights from tip-growing plant and fungal cells. J Cell Sci 2022; 135:280540. [DOI: 10.1242/jcs.259208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ABSTRACT
The cell wall (CW) is a thin and rigid layer encasing the membrane of all plant and fungal cells. It ensures mechanical integrity by bearing mechanical stresses derived from large cytoplasmic turgor pressure, contacts with growing neighbors or growth within restricted spaces. The CW is made of polysaccharides and proteins, but is dynamic in nature, changing composition and geometry during growth, reproduction or infection. Such continuous and often rapid remodeling entails risks of enhanced stress and consequent damages or fractures, raising the question of how the CW detects and measures surface mechanical stress and how it strengthens to ensure surface integrity? Although early studies in model fungal and plant cells have identified homeostatic pathways required for CW integrity, recent methodologies are now allowing the measurement of pressure and local mechanical properties of CWs in live cells, as well as addressing how forces and stresses can be detected at the CW surface, fostering the emergence of the field of CW mechanobiology. Here, using tip-growing cells of plants and fungi as case study models, we review recent progress on CW mechanosensation and mechanical regulation, and their implications for the control of cell growth, morphogenesis and survival.
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Affiliation(s)
- Celia Municio-Diaz
- Université de Paris, CNRS, Institut Jacques Monod 1 , F-75006 Paris , France
- Equipe Labellisée LIGUE Contre le Cancer 2 , 75013 Paris , France
| | - Elise Muller
- LadHyX, CNRS, Ecole polytechnique, Institut Polytechnique de Paris 3 , 91128 Palaiseau Cedex , France
| | - Stéphanie Drevensek
- LadHyX, CNRS, Ecole polytechnique, Institut Polytechnique de Paris 3 , 91128 Palaiseau Cedex , France
| | - Antoine Fruleux
- LPTMS, CNRS, Université Paris-Saclay 4 , 91405 Orsay , France
| | - Enrico Lorenzetti
- LadHyX, CNRS, Ecole polytechnique, Institut Polytechnique de Paris 3 , 91128 Palaiseau Cedex , France
| | - Arezki Boudaoud
- LadHyX, CNRS, Ecole polytechnique, Institut Polytechnique de Paris 3 , 91128 Palaiseau Cedex , France
| | - Nicolas Minc
- Université de Paris, CNRS, Institut Jacques Monod 1 , F-75006 Paris , France
- Equipe Labellisée LIGUE Contre le Cancer 2 , 75013 Paris , France
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9
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Sinha D, Ivan D, Gibbs E, Chetluru M, Goss J, Chen Q. Fission yeast polycystin Pkd2p promotes cell size expansion and antagonizes the Hippo-related SIN pathway. J Cell Sci 2022; 135:274457. [PMID: 35099006 PMCID: PMC8919332 DOI: 10.1242/jcs.259046] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 01/14/2022] [Indexed: 11/20/2022] Open
Abstract
Polycystins are conserved mechanosensitive channels whose mutations lead to the common human renal disorder autosomal dominant polycystic kidney disease (ADPKD). Previously, we discovered that the plasma membrane-localized fission yeast polycystin homolog Pkd2p is an essential protein required for cytokinesis; however, its role remains unclear. Here, we isolated a novel temperature-sensitive pkd2 mutant, pkd2-B42. Among the strong growth defects of this mutant, the most striking was that many mutant cells often lost a significant portion of their volume in just 5 min followed by a gradual recovery, a process that we termed 'deflation'. Unlike cell lysis, deflation did not result in plasma membrane rupture and occurred independently of cell cycle progression. The tip extension of pkd2-B42 cells was 80% slower than that of wild-type cells, and their turgor pressure was 50% lower. Both pkd2-B42 and the hypomorphic depletion mutant pkd2-81KD partially rescued mutants of the septation initiation network (SIN), a yeast Hippo-related signaling pathway, by preventing cell lysis, enhancing septum formation and doubling the number of Sid2p and Mob1p molecules at the spindle pole bodies. We conclude that Pkd2p promotes cell size expansion during interphase by regulating turgor pressure and antagonizes the SIN during cytokinesis. This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Debatrayee Sinha
- Department of Biological Sciences, The University of Toledo, 2801 West Bancroft St, Toledo, OH 43606, USA
| | - Denisa Ivan
- Department of Biological Sciences, The University of Toledo, 2801 West Bancroft St, Toledo, OH 43606, USA
| | - Ellie Gibbs
- Department of Biological Sciences, Wellesley College, 106 Central Street, Wellesley, MA 02482, USA
| | - Madhurya Chetluru
- Department of Biological Sciences, The University of Toledo, 2801 West Bancroft St, Toledo, OH 43606, USA
| | - John Goss
- Department of Biological Sciences, Wellesley College, 106 Central Street, Wellesley, MA 02482, USA
| | - Qian Chen
- Department of Biological Sciences, The University of Toledo, 2801 West Bancroft St, Toledo, OH 43606, USA,Author for correspondence ()
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10
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Cells under pressure: how yeast cells respond to mechanical forces. Trends Microbiol 2022; 30:495-510. [PMID: 35000797 DOI: 10.1016/j.tim.2021.11.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 10/31/2021] [Accepted: 11/08/2021] [Indexed: 11/23/2022]
Abstract
In their natural habitats, unicellular fungal microbes are exposed to a myriad of mechanical cues such as shear forces from fluid flow, osmotic changes, and contact forces arising from microbial expansion in confined niches. While the rigidity of the cell wall is critical to withstand such external forces and balance high internal turgor pressure, it poses mechanical challenges during physiological processes such as cell growth, division, and mating that require cell wall remodeling. Thus, even organisms as simple as yeast have evolved complex signaling networks to sense and respond to intrinsic and extrinsic mechanical forces. In this review, we summarize the type and origin of mechanical forces experienced by unicellular yeast and discuss how these forces reorganize cell polarity and how pathogenic fungi exploit polarized assemblies to track weak spots in host tissues for successful penetration. We then describe mechanisms of force-sensing by conserved sets of mechanosensors. Finally, we elaborate downstream mechanotransduction mechanisms that orchestrate appropriate cellular responses, leading to improved mechanical fitness.
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11
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Bibeau JP, Galotto G, Wu M, Tüzel E, Vidali L. Quantitative cell biology of tip growth in moss. PLANT MOLECULAR BIOLOGY 2021; 107:227-244. [PMID: 33825083 PMCID: PMC8492783 DOI: 10.1007/s11103-021-01147-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 03/25/2021] [Indexed: 05/16/2023]
Abstract
KEY MESSAGE Here we review, from a quantitative point of view, the cell biology of protonemal tip growth in the model moss Physcomitrium patens. We focus on the role of the cytoskeleton, vesicle trafficking, and cell wall mechanics, including reviewing some of the existing mathematical models of tip growth. We provide a primer for existing cell biological tools that can be applied to the future study of tip growth in moss. Polarized cell growth is a ubiquitous process throughout the plant kingdom in which the cell elongates in a self-similar manner. This process is important for nutrient uptake by root hairs, fertilization by pollen, and gametophyte development by the protonemata of bryophytes and ferns. In this review, we will focus on the tip growth of moss cells, emphasizing the role of cytoskeletal organization, cytoplasmic zonation, vesicle trafficking, cell wall composition, and dynamics. We compare some of the existing knowledge on tip growth in protonemata against what is known in pollen tubes and root hairs, which are better-studied tip growing cells. To fully understand how plant cells grow requires that we deepen our knowledge in a variety of forms of plant cell growth. We focus this review on the model plant Physcomitrium patens, which uses tip growth as the dominant form of growth at its protonemal stage. Because mosses and vascular plants shared a common ancestor more than 450 million years ago, we anticipate that both similarities and differences between tip growing plant cells will provide mechanistic information of tip growth as well as of plant cell growth in general. Towards this mechanistic understanding, we will also review some of the existing mathematical models of plant tip growth and their applicability to investigate protonemal morphogenesis. We attempt to integrate the conclusions and data across cell biology and physical modeling to our current state of knowledge of polarized cell growth in P. patens and highlight future directions in the field.
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Affiliation(s)
- Jeffrey P Bibeau
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Giulia Galotto
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Min Wu
- Department of Mathematical Sciences, Worcester Polytechnic Institute, Worcester, MA, USA
- Bioinformatics and Computational Biology Program, Worcester Polytechnic Institute, Worcester, MA, USA
| | - Erkan Tüzel
- Bioengineering Department, Temple University, Philadelphia, PA, USA
| | - Luis Vidali
- Department of Biology and Biotechnology, Worcester Polytechnic Institute, Worcester, MA, USA.
- Bioinformatics and Computational Biology Program, Worcester Polytechnic Institute, Worcester, MA, USA.
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12
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Dumais J. Mechanics and hydraulics of pollen tube growth. THE NEW PHYTOLOGIST 2021; 232:1549-1565. [PMID: 34492127 DOI: 10.1111/nph.17722] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 08/21/2021] [Indexed: 06/13/2023]
Abstract
All kingdoms of life have evolved tip-growing cells able to mine their environment or deliver cargo to remote targets. The basic cellular processes supporting these functions are understood in increasing detail, but the multiple interactions between them lead to complex responses that require quantitative models to be disentangled. Here, I review the equations that capture the fundamental interactions between wall mechanics and cell hydraulics starting with a detailed presentation of James Lockhart's seminal model. The homeostatic feedbacks needed to maintain a steady tip velocity are then shown to offer a credible explanation for the pulsatile growth observed in some tip-growing cells. Turgor pressure emerges as a central variable whose role in the morphogenetic process has been a source of controversy for more than 50 yr. I argue that recasting Lockhart's work as a process of chemical stress relaxation can clarify how cells control tip growth and help us internalise the important but passive role played by turgor pressure in the morphogenetic process.
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Affiliation(s)
- Jacques Dumais
- Faculty of Engineering and Sciences, Universidad Adolfo Ibáñez, Av. Padre Hurtado 750, Viña del Mar, Region of Valparaíso, Chile
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13
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Neeli-Venkata R, Diaz CM, Celador R, Sanchez Y, Minc N. Detection of surface forces by the cell-wall mechanosensor Wsc1 in yeast. Dev Cell 2021; 56:2856-2870.e7. [PMID: 34666001 DOI: 10.1016/j.devcel.2021.09.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 07/13/2021] [Accepted: 09/24/2021] [Indexed: 11/19/2022]
Abstract
Surface receptors of animal cells, such as integrins, promote mechanosensation by forming clusters as signaling hubs that transduce tensile forces. Walled cells of plants and fungi also feature surface sensors, with long extracellular domains that are embedded in their cell walls (CWs) and are thought to detect injuries and promote repair. How these sensors probe surface forces remains unknown. By studying the conserved CW sensor Wsc1 in fission yeast, we uncovered the formation of micrometer-sized clusters at sites of force application onto the CW. Clusters assembled within minutes of CW compression, in dose dependence with mechanical stress and disassembled upon relaxation. Our data support that Wsc1 accumulates to sites of enhanced mechanical stress through reduced lateral diffusivity, mediated by the binding of its extracellular WSC domain to CW polysaccharides, independent of canonical polarity, trafficking, and downstream CW regulatory pathways. Wsc1 may represent an autonomous module to detect and transduce local surface forces onto the CW.
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Affiliation(s)
- Ramakanth Neeli-Venkata
- Université de Paris, CNRS, Institut Jacques Monod, 75006 Paris, France; Equipe Labellisée LIGUE Contre le Cancer, Paris, France
| | - Celia Municio Diaz
- Université de Paris, CNRS, Institut Jacques Monod, 75006 Paris, France; Equipe Labellisée LIGUE Contre le Cancer, Paris, France
| | - Ruben Celador
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca and Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Zacarías González, 37007 Salamanca, Spain
| | - Yolanda Sanchez
- Instituto de Biología Funcional y Genómica, CSIC/Universidad de Salamanca and Departamento de Microbiología y Genética, Universidad de Salamanca, C/ Zacarías González, 37007 Salamanca, Spain
| | - Nicolas Minc
- Université de Paris, CNRS, Institut Jacques Monod, 75006 Paris, France; Equipe Labellisée LIGUE Contre le Cancer, Paris, France.
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14
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Miller KE, Magliozzi JO, Picard NA, Moseley JB. Sequestration of the exocytic SNARE Psy1 into multiprotein nodes reinforces polarized morphogenesis in fission yeast. Mol Biol Cell 2021; 32:ar7. [PMID: 34347508 PMCID: PMC8684755 DOI: 10.1091/mbc.e20-05-0277] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 07/06/2021] [Accepted: 07/29/2021] [Indexed: 11/11/2022] Open
Abstract
Polarized morphogenesis is achieved by targeting or inhibiting growth in distinct regions. Rod-shaped fission yeast cells grow exclusively at their ends by restricting exocytosis and secretion to these sites. This growth pattern implies the existence of mechanisms that prevent exocytosis and growth along nongrowing cell sides. We previously identified a set of 50-100 megadalton-sized node structures along the sides of fission yeast cells that contained the interacting proteins Skb1 and Slf1. Here, we show that Skb1-Slf1 nodes contain the syntaxin-like soluble N-ethylmaleimide-sensitive factor attachment protein receptor Psy1, which mediates exocytosis in fission yeast. Psy1 localizes in a diffuse pattern at cell tips, where it likely promotes exocytosis and growth, but is sequestered in Skb1-Slf1 nodes at cell sides where growth does not occur. Mutations that prevent node assembly or inhibit Psy1 localization to nodes lead to aberrant exocytosis at cell sides and increased cell width. Genetic results indicate that this Psy1 node mechanism acts in parallel to actin cables and Cdc42 regulation. Our work suggests that sequestration of syntaxin-like Psy1 at nongrowing regions of the cell cortex reinforces cell morphology by restricting exocytosis to proper sites of polarized growth.
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Affiliation(s)
- Kristi E. Miller
- Department of Biochemistry and Cell Biology, the Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Joseph O. Magliozzi
- Department of Biochemistry and Cell Biology, the Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - Noelle A. Picard
- Department of Biochemistry and Cell Biology, the Geisel School of Medicine at Dartmouth, Hanover, NH 03755
| | - James B. Moseley
- Department of Biochemistry and Cell Biology, the Geisel School of Medicine at Dartmouth, Hanover, NH 03755
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15
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Gibbs E, Hsu J, Barth K, Goss JW. Characterization of the nanomechanical properties of the fission yeast (Schizosaccharomyces pombe) cell surface by atomic force microscopy. Yeast 2021; 38:480-492. [PMID: 33913187 PMCID: PMC9291503 DOI: 10.1002/yea.3564] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 04/14/2021] [Accepted: 04/23/2021] [Indexed: 11/11/2022] Open
Abstract
Variations in cell wall composition and biomechanical properties can contribute to the cellular plasticity required during complex processes such as polarized growth and elongation in microbial cells. This study utilizes atomic force microscopy (AFM) to map the cell surface topography of fission yeast, Schizosaccharomyces pombe, at the pole regions and to characterize the biophysical properties within these regions under physiological, hydrated conditions. High-resolution images acquired from AFM topographic scanning reveal decreased surface roughness at the cell poles. Force extension curves acquired by nanoindentation probing with AFM cantilever tips under low applied force revealed increased cell wall deformation and decreased cellular stiffness (cellular spring constant) at cell poles (17 ± 4 mN/m) relative to the main body of the cell that is not undergoing growth and expansion (44 ± 10 mN/m). These findings suggest that the increased deformation and decreased stiffness at regions of polarized growth at fission yeast cell poles provide the plasticity necessary for cellular extension. This study provides a direct biophysical characterization of the S. pombe cell surface by AFM, and it provides a foundation for future investigation of how the surface topography and local nanomechanical properties vary during different cellular processes.
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Affiliation(s)
- Ellie Gibbs
- Department of Biological Sciences, Wellesley College, Wellesley, MA, USA
| | - Justine Hsu
- Biochemistry Program, Wellesley College, Wellesley, MA, USA
| | - Kathryn Barth
- Biochemistry Program, Wellesley College, Wellesley, MA, USA
| | - John W Goss
- Department of Biological Sciences, Wellesley College, Wellesley, MA, USA.,Biochemistry Program, Wellesley College, Wellesley, MA, USA
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16
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Dünkler A, Leda M, Kromer JM, Neller J, Gronemeyer T, Goryachev AB, Johnsson N. Type V myosin focuses the polarisome and shapes the tip of yeast cells. J Cell Biol 2021; 220:211845. [PMID: 33656555 PMCID: PMC7933982 DOI: 10.1083/jcb.202006193] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 01/25/2021] [Accepted: 02/04/2021] [Indexed: 11/22/2022] Open
Abstract
The polarisome is a cortical proteinaceous microcompartment that organizes the growth of actin filaments and the fusion of secretory vesicles in yeasts and filamentous fungi. Polarisomes are compact, spotlike structures at the growing tips of their respective cells. The molecular forces that control the form and size of this microcompartment are not known. Here we identify a complex between the polarisome subunit Pea2 and the type V Myosin Myo2 that anchors Myo2 at the cortex of yeast cells. We discovered a point mutation in the cargo-binding domain of Myo2 that impairs the interaction with Pea2 and consequently the formation and focused localization of the polarisome. Cells carrying this mutation grow round instead of elongated buds. Further experiments and biophysical modeling suggest that the interactions between polarisome-bound Myo2 motors and dynamic actin filaments spatially focus the polarisome and sustain its compact shape.
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Affiliation(s)
- Alexander Dünkler
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, Ulm, Germany
| | - Marcin Leda
- Centre for Synthetic and Systems Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Jan-Michael Kromer
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, Ulm, Germany
| | - Joachim Neller
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, Ulm, Germany
| | - Thomas Gronemeyer
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, Ulm, Germany
| | - Andrew B Goryachev
- Centre for Synthetic and Systems Biology, Institute of Cell Biology, University of Edinburgh, Edinburgh, UK
| | - Nils Johnsson
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, Ulm, Germany
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17
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Balancing of the mitotic exit network and cell wall integrity signaling governs the development and pathogenicity in Magnaporthe oryzae. PLoS Pathog 2021; 17:e1009080. [PMID: 33411855 PMCID: PMC7817018 DOI: 10.1371/journal.ppat.1009080] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 01/20/2021] [Accepted: 10/20/2020] [Indexed: 11/25/2022] Open
Abstract
The fungal cell wall plays an essential role in maintaining cell morphology, transmitting external signals, controlling cell growth, and even virulence. Relaxation and irreversible stretching of the cell wall are the prerequisites of cell division and development, but they also inevitably cause cell wall stress. Both Mitotic Exit Network (MEN) and Cell Wall Integrity (CWI) are signaling pathways that govern cell division and cell stress response, respectively, how these pathways cross talk to govern and coordinate cellular growth, development, and pathogenicity remains not fully understood. We have identified MoSep1, MoDbf2, and MoMob1 as the conserved components of MEN from the rice blast fungus Magnaporthe oryzae. We have found that blocking cell division results in abnormal CWI signaling. In addition, we discovered that MoSep1 targets MoMkk1, a conserved key MAP kinase of the CWI pathway, through protein phosphorylation that promotes CWI signaling. Moreover, we provided evidence demonstrating that MoSep1-dependent MoMkk1 phosphorylation is essential for balancing cell division with CWI that maintains the dynamic stability required for virulence of the blast fungus. The cell wall is a relatively rigid structure for supporting the cell shape and against extracellular stresses. However, it also maintains plasticity to cope with cell division, growth, and differentiation. In the rice blast pathogenic fungus Magnaporthe oryzae, such differentiation corresponds directly to its virulence. Thus, how to balance the “strong for shaping” with the “malleable for growth and virulence” poses as an important question of both basic- and applied science of significance. We here report that the protein kinase MoSep1 links the Mitotic Exit Network (MEN) to the Cell Wall Integrity (CWI) signaling through the phosphorylation of the CWI MAP kinase kinase MoMkk1. We found that the MoSep1-dependent phosphorylation of MoMkk1 relieves the cell wall stress caused by cell division and that the MEN-CWI-mediated balance of rigid and remodeling of the cell wall is important in the growth, development, and virulence of the blast fungus. Our study provides a new evidence on how the blast fungus adapts to self-generated stress for growth and virulence and it sheds new light on the crosstalk between MEN and CWI signaling.
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18
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Taheraly S, Ershov D, Dmitrieff S, Minc N. An image analysis method to survey the dynamics of polar protein abundance in the regulation of tip growth. J Cell Sci 2020; 133:133/22/jcs252064. [PMID: 33257499 DOI: 10.1242/jcs.252064] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 10/14/2020] [Indexed: 11/20/2022] Open
Abstract
Tip growth is critical for the lifestyle of many walled cells. In yeast and fungi, this process is typically associated with the polarized deposition of conserved tip factors, including landmarks, Rho GTPases, cytoskeleton regulators, and membrane and cell wall remodelers. Because tip growth speeds may vary extensively between life cycles or species, we asked whether the local amount of specific polar elements could determine or limit tip growth speeds. Using the model fission yeast, we developed a quantitative image analysis pipeline to dynamically correlate single tip elongation speeds and polar protein abundance in large data sets. We found that polarity landmarks are typically diluted by growth. In contrast, tip growth speed is positively correlated with the local amount of factors related to actin, secretion or cell wall remodeling, but, surprisingly, exhibits long saturation plateaus above certain concentrations of those factors. Similar saturation observed for Spitzenkörper components in much faster growing fungal hyphae suggests that elements independent of canonical surface remodelers may limit single tip growth. This work provides standardized methods and resources to decipher the complex mechanisms that control cell growth.This article has an associated First Person interview with Sarah Taheraly, joint first author of the paper.
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Affiliation(s)
- Sarah Taheraly
- Université de Paris, CNRS, Institut Jacques Monod, 75013, Paris, France
| | - Dmitry Ershov
- Université de Paris, CNRS, Institut Jacques Monod, 75013, Paris, France
| | - Serge Dmitrieff
- Université de Paris, CNRS, Institut Jacques Monod, 75013, Paris, France
| | - Nicolas Minc
- Université de Paris, CNRS, Institut Jacques Monod, 75013, Paris, France
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19
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Poddar A, Sidibe O, Ray A, Chen Q. Calcium spikes accompany cleavage furrow ingression and cell separation during fission yeast cytokinesis. Mol Biol Cell 2020; 32:15-27. [PMID: 33175606 PMCID: PMC8098820 DOI: 10.1091/mbc.e20-09-0609] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The role of calcium signaling in cytokinesis has long remained ambiguous. Past studies of embryonic cell division discovered that calcium concentration increases transiently at the division plane just before cleavage furrow ingression, suggesting that these calcium transients could trigger contractile ring constriction. However, such calcium transients have only been found in animal embryos and their function remains controversial. We explored cytokinetic calcium transients in the fission yeast Schizosaccharomyces pombe by adopting GCaMP, a genetically encoded calcium indicator, to determine the intracellular calcium level of this model organism. We validated GCaMP as a highly sensitive calcium reporter in fission yeast, allowing us to capture calcium transients triggered by osmotic shocks. We identified a correlation between the intracellular calcium level and cell division, consistent with the existence of calcium transients during cytokinesis. Using time-lapse microscopy and quantitative image analysis, we discovered calcium spikes both at the start of cleavage furrow ingression and the end of cell separation. Inhibition of these calcium spikes slowed the furrow ingression and led to frequent lysis of daughter cells. We conclude that like the larger animal embryos, fission yeast triggers calcium transients that may play an important role in cytokinesis (197).
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Affiliation(s)
- Abhishek Poddar
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
| | - Oumou Sidibe
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
| | - Aniruddha Ray
- Department of Physics and Astronomy, University of Toledo, Toledo, OH 43606
| | - Qian Chen
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
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20
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Knapp BD, Odermatt P, Rojas ER, Cheng W, He X, Huang KC, Chang F. Decoupling of Rates of Protein Synthesis from Cell Expansion Leads to Supergrowth. Cell Syst 2019; 9:434-445.e6. [PMID: 31706948 PMCID: PMC6911364 DOI: 10.1016/j.cels.2019.10.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 07/02/2019] [Accepted: 09/30/2019] [Indexed: 01/02/2023]
Abstract
Cell growth is a complex process in which cells synthesize cellular components while they increase in size. It is generally assumed that the rate of biosynthesis must somehow be coordinated with the rate of growth in order to maintain intracellular concentrations. However, little is known about potential feedback mechanisms that could achieve proteome homeostasis or the consequences when this homeostasis is perturbed. Here, we identify conditions in which fission yeast cells are prevented from volume expansion but nevertheless continue to synthesize biomass, leading to general accumulation of proteins and increased cytoplasmic density. Upon removal of these perturbations, this biomass accumulation drove cells to undergo a multi-generational period of "supergrowth" wherein rapid volume growth outpaced biosynthesis, returning proteome concentrations back to normal within hours. These findings demonstrate a mechanism for global proteome homeostasis based on modulation of volume growth and dilution.
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Affiliation(s)
- Benjamin D Knapp
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA; Biophysics Program, Stanford University, Stanford, CA 94305, USA
| | - Pascal Odermatt
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Enrique R Rojas
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Wenpeng Cheng
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Xiangwei He
- Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310027, China
| | - Kerwyn Casey Huang
- Biophysics Program, Stanford University, Stanford, CA 94305, USA; Department of Bioengineering, Stanford University, Stanford, CA 94305, USA; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, San Francisco, CA 941586, USA.
| | - Fred Chang
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143, USA.
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21
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Systematic mapping of cell wall mechanics in the regulation of cell morphogenesis. Proc Natl Acad Sci U S A 2019; 116:13833-13838. [PMID: 31235592 DOI: 10.1073/pnas.1820455116] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Walled cells of plants, fungi, and bacteria come with a large range of shapes and sizes, which are ultimately dictated by the mechanics of their cell wall. This stiff and thin polymeric layer encases the plasma membrane and protects the cells mechanically by opposing large turgor pressure derived mechanical stresses. To date, however, we still lack a quantitative understanding for how local and/or global mechanical properties of the wall support cell morphogenesis. Here, we combine subresolution imaging and laser-mediated wall relaxation to quantitate subcellular values of wall thickness (h) and bulk elastic moduli (Y) in large populations of live mutant cells and in conditions affecting cell diameter in the rod-shaped model fission yeast. We find that lateral wall stiffness, defined by the surface modulus, σ = hY, robustly scales with cell diameter. This scaling is valid across tens of mutants spanning various functions-within the population of individual isogenic strains, along single misshaped cells, and even across the fission yeasts clade. Dynamic modulations of cell diameter by chemical and/or mechanical means suggest that the cell wall can rapidly adapt its surface mechanics, rendering stretched wall portions stiffer than unstretched ones. Size-dependent wall stiffening constrains diameter definition and limits size variations; it may also provide an efficient means to keep elastic strains in the wall below failure strains, potentially promoting cell survival. This quantitative set of data impacts our current understanding of the mechanics of cell walls and its contribution to morphogenesis.
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22
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Morris Z, Sinha D, Poddar A, Morris B, Chen Q. Fission yeast TRP channel Pkd2p localizes to the cleavage furrow and regulates cell separation during cytokinesis. Mol Biol Cell 2019; 30:1791-1804. [PMID: 31116668 PMCID: PMC6727746 DOI: 10.1091/mbc.e18-04-0270] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Force plays a central role in separating daughter cells during cytokinesis, the last stage of cell division. However, the mechanism of force sensing during cytokinesis remains unknown. Here we discovered that Pkd2p, a putative force-sensing transient receptor potential channel, localizes to the cleavage furrow during cytokinesis of the fission yeast, Schizosaccharomyces pombe. Pkd2p, whose human homologues are associated with autosomal polycystic kidney disease, is an essential protein whose localization depends on the contractile ring and the secretory pathway. We identified and characterized a novel pkd2 mutant pkd2-81KD. The pkd2 mutant cells show signs of osmotic stress, including temporary shrinking, paused turnover of the cytoskeletal structures, and hyperactivated mitogen-activated protein kinase signaling. During cytokinesis, although the contractile ring constricts more rapidly in the pkd2 mutant than the wild-type cells (50% higher), the cell separation in the mutant is slower and often incomplete. These cytokinesis defects are also consistent with misregulated turgor pressure. Finally, the pkd2 mutant exhibits strong genetic interactions with two mutants of the septation initiation network pathway, a signaling cascade essential for cytokinesis. We propose that Pkd2p modulates osmotic homeostasis and is potentially a novel regulator of cytokinesis.
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Affiliation(s)
- Zachary Morris
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
| | - Debatrayee Sinha
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
| | - Abhishek Poddar
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
| | - Brittni Morris
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
| | - Qian Chen
- Department of Biological Sciences, University of Toledo, Toledo, OH 43606
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23
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Xu B, Jilkine A. Modeling the Dynamics of Cdc42 Oscillation in Fission Yeast. Biophys J 2019; 114:711-722. [PMID: 29414716 DOI: 10.1016/j.bpj.2017.12.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 11/27/2017] [Accepted: 12/11/2017] [Indexed: 11/17/2022] Open
Abstract
Regulation of polarized cell growth is essential for many cellular processes, including spatial coordination of cell morphology changes during growth and division. We present a mathematical model of the core mechanism responsible for the regulation of polarized growth dynamics by the small GTPase Cdc42. The model is based on the competition of growth zones of Cdc42 localized at the cell tips for a common substrate (inactive Cdc42) that diffuses in the cytosol. We consider several potential ways of implementing negative feedback between Cd42 and its GEF in this model that would be consistent with the observed oscillations of Cdc42 in fission yeast. We analyze the bifurcations in this model as the cell length increases, and total amount of Cdc42 and GEF increase. Symmetric antiphase oscillations at two tips emerge via saddle-homoclinic bifurcations or Hopf bifurcations. We find that a stable oscillation and a stable steady state can coexist, which is consistent with the experimental finding that only 50% of bipolar cells oscillate. The mean amplitude and period can be tuned by parameters involved in the negative feedback. We link modifications in the parameters of the model to observed mutant phenotypes. Our model suggests that negative feedback is more likely to be acting through inhibition of GEF association rather than upregulation of GEF dissociation.
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Affiliation(s)
- Bin Xu
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, Indiana.
| | - Alexandra Jilkine
- Department of Applied and Computational Mathematics and Statistics, University of Notre Dame, Notre Dame, Indiana.
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24
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Gu Y, Oliferenko S. Cellular geometry scaling ensures robust division site positioning. Nat Commun 2019; 10:268. [PMID: 30664646 PMCID: PMC6341079 DOI: 10.1038/s41467-018-08218-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 12/19/2018] [Indexed: 11/16/2022] Open
Abstract
Cells of a specific cell type may divide within a certain size range. Yet, functionally optimal cellular organization is typically maintained across different cell sizes, a phenomenon known as scaling. The mechanisms underlying scaling and its physiological significance remain elusive. Here we approach this problem by interfering with scaling in the rod-shaped fission yeast Schizosaccharomyces japonicus that relies on cellular geometry cues to position the division site. We show that S. japonicus uses the Cdc42 polarity module to adjust its geometry to changes in the cell size. When scaling is prevented resulting in abnormal cellular length-to-width aspect ratio, cells exhibit severe division site placement defects. We further show that despite the generally accepted view, a similar scaling phenomenon can occur in the sister species, Schizosaccharomyces pombe. Our results demonstrate that scaling is required for normal cell function and delineate possible rules for cellular geometry maintenance in populations of proliferating cells. Cells divide within a given size range and can scale across differing cell sizes but mechanisms and function remain unclear. Here the authors show, despite the current dogma of fission yeast maintaining constant width, some fission yeast can scale their width and length, impacting the positioning of the cell division site.
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Affiliation(s)
- Ying Gu
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK.,Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, SE1 1UL, UK
| | - Snezhana Oliferenko
- The Francis Crick Institute, 1 Midland Road, London, NW1 1AT, UK. .,Randall Centre for Cell and Molecular Biophysics, School of Basic and Medical Biosciences, King's College London, London, SE1 1UL, UK.
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25
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Hemelryck MV, Bernal R, Ispolatov Y, Dumais J. Lily Pollen Tubes Pulse According to a Simple Spatial Oscillator. Sci Rep 2018; 8:12135. [PMID: 30108317 PMCID: PMC6092427 DOI: 10.1038/s41598-018-30635-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Accepted: 06/07/2018] [Indexed: 11/23/2022] Open
Abstract
Polar growth is a fundamental mode of cell morphogenesis observed in nearly all major groups of organisms. Among polarly growing cells, the angiosperm pollen tubes have emerged as powerful experimental systems in large part because of their oscillatory growth, which provides a window into the network of interactions regulating morphogenesis. Empirical studies of oscillatory pollen tubes have sought to uncover the temporal sequence of cellular and molecular events that constitutes an oscillatory cycle. Here we show that in lily pollen tubes the distance or wavelength (λ = 6.3 ± 1.7 μm) over which an oscillatory cycle unfolds is more robust than the period of oscillation (τ = 39.1 ± 17.6 s) (n = 159 cells). Moreover, the oscillatory cycle is divided into slow and fast phases, with each phase unfolding over precisely one half of the wavelength. Using these observations, we show that a simple spatial bi-oscillator predicts the most common modes of oscillation observed in pollen tubes. These results call into question the traditional view of pollen tube morphogenesis as a temporal succession of cellular events. Space, not time, may be the most natural metric to inteprete the morphogenetic dynamics of these cells.
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Affiliation(s)
| | - Roberto Bernal
- Departamento de Física, Universidad de Santiago de Chile, Santiago, 9170124, Chile
| | - Yaroslav Ispolatov
- Departamento de Física, Universidad de Santiago de Chile, Santiago, 9170124, Chile
| | - Jacques Dumais
- Facultad de Ingeniería y Ciencias, Universidad Adolfo Ibáñez, Viña del Mar, Region V, Chile.
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26
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Julien JD, Boudaoud A. Elongation and shape changes in organisms with cell walls: A dialogue between experiments and models. ACTA ACUST UNITED AC 2018; 1:34-42. [PMID: 32743126 PMCID: PMC7388974 DOI: 10.1016/j.tcsw.2018.04.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 04/06/2018] [Accepted: 04/08/2018] [Indexed: 11/28/2022]
Abstract
The generation of anisotropic shapes occurs during morphogenesis of almost all organisms. With the recent renewal of the interest in mechanical aspects of morphogenesis, it has become clear that mechanics contributes to anisotropic forms in a subtle interaction with various molecular actors. Here, we consider plants, fungi, oomycetes, and bacteria, and we review the mechanisms by which elongated shapes are generated and maintained. We focus on theoretical models of the interplay between growth and mechanics, in relation with experimental data, and discuss how models may help us improve our understanding of the underlying biological mechanisms.
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Affiliation(s)
- Jean-Daniel Julien
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, 46 allée d'Italie, 69364 Lyon Cedex 07, France.,Laboratoire de Physique, Univ. Lyon, ENS de Lyon, UCB Lyon 1, CNRS, 46 allée d'Italie, 69364 Lyon Cedex 07, France
| | - Arezki Boudaoud
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, 46 allée d'Italie, 69364 Lyon Cedex 07, France
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27
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Davì V, Tanimoto H, Ershov D, Haupt A, De Belly H, Le Borgne R, Couturier E, Boudaoud A, Minc N. Mechanosensation Dynamically Coordinates Polar Growth and Cell Wall Assembly to Promote Cell Survival. Dev Cell 2018; 45:170-182.e7. [DOI: 10.1016/j.devcel.2018.03.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 02/05/2018] [Accepted: 03/26/2018] [Indexed: 02/03/2023]
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28
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Banavar SP, Gomez C, Trogdon M, Petzold LR, Yi TM, Campàs O. Mechanical feedback coordinates cell wall expansion and assembly in yeast mating morphogenesis. PLoS Comput Biol 2018; 14:e1005940. [PMID: 29346368 PMCID: PMC5790295 DOI: 10.1371/journal.pcbi.1005940] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 01/30/2018] [Accepted: 12/22/2017] [Indexed: 11/18/2022] Open
Abstract
The shaping of individual cells requires a tight coordination of cell mechanics and growth. However, it is unclear how information about the mechanical state of the wall is relayed to the molecular processes building it, thereby enabling the coordination of cell wall expansion and assembly during morphogenesis. Combining theoretical and experimental approaches, we show that a mechanical feedback coordinating cell wall assembly and expansion is essential to sustain mating projection growth in budding yeast (Saccharomyces cerevisiae). Our theoretical results indicate that the mechanical feedback provided by the Cell Wall Integrity pathway, with cell wall stress sensors Wsc1 and Mid2 increasingly activating membrane-localized cell wall synthases Fks1/2 upon faster cell wall expansion, stabilizes mating projection growth without affecting cell shape. Experimental perturbation of the osmotic pressure and cell wall mechanics, as well as compromising the mechanical feedback through genetic deletion of the stress sensors, leads to cellular phenotypes that support the theoretical predictions. Our results indicate that while the existence of mechanical feedback is essential to stabilize mating projection growth, the shape and size of the cell are insensitive to the feedback.
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Affiliation(s)
- Samhita P. Banavar
- Department of Physics, University of California, Santa Barbara, Santa Barbara, California, United States of America
- California NanoSystems Institute, University of California, Santa Barbara, Santa Barbara, California, United States of America
| | - Carlos Gomez
- California NanoSystems Institute, University of California, Santa Barbara, Santa Barbara, California, United States of America
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California, United States of America
| | - Michael Trogdon
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, California, United States of America
| | - Linda R. Petzold
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, California, United States of America
- Center for Bioengineering, University of California, Santa Barbara, Santa Barbara, United States of America
| | - Tau-Mu Yi
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California, United States of America
| | - Otger Campàs
- California NanoSystems Institute, University of California, Santa Barbara, Santa Barbara, California, United States of America
- Department of Molecular, Cell and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California, United States of America
- Department of Mechanical Engineering, University of California, Santa Barbara, Santa Barbara, California, United States of America
- Center for Bioengineering, University of California, Santa Barbara, Santa Barbara, United States of America
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29
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ER-PM Contacts Restrict Exocytic Sites for Polarized Morphogenesis. Curr Biol 2017; 28:146-153.e5. [PMID: 29290560 DOI: 10.1016/j.cub.2017.11.055] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Revised: 10/31/2017] [Accepted: 11/22/2017] [Indexed: 01/04/2023]
Abstract
Spatial control of exocytosis underlies polarized cell morphogenesis. In rod-shaped fission yeast, exocytic vesicles are conveyed along the actin cytoskeleton by myosin V motors toward growing cell ends [1, 2], the major sites for exocytosis. However, actomyosin-based vesicle delivery is dispensable for polarized secretion and cylindrical cell shape of fission yeast [3]. Thus, additional mechanisms should function in the spatial confinement of exocytosis. Here we report a novel role of endoplasmic reticulum (ER)-plasma membrane (PM) contacts in restricting exocytic sites for polarized fission yeast morphogenesis. We show that fission yeast cells deficient in both ER-PM contacts and actomyosin-based secretory vesicle transport display aberrant globular cell shape due to delocalized exocytosis. By artificially manipulating the strength and extent of ER-PM contacts in wild-type and mutant cells that exhibit induced ectopic exocytosis, we demonstrate that exocytosis and ER-PM contact formation are spatially incompatible. Furthermore, extensive ER-PM junctions at the non-growing lateral cell cortex prevent the PM from exocytic vesicle tethering and hence attenuate growth potential at cell sides. We thus propose that ER-PM contacts function as a new morphogenetic module by limiting exocytosis to growing cell tips in fission yeast. A similar mechanism could apply to other cell types with prominent ER-PM contacts.
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30
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Luo N, Yan A, Liu G, Guo J, Rong D, Kanaoka MM, Xiao Z, Xu G, Higashiyama T, Cui X, Yang Z. Exocytosis-coordinated mechanisms for tip growth underlie pollen tube growth guidance. Nat Commun 2017; 8:1687. [PMID: 29162819 PMCID: PMC5698331 DOI: 10.1038/s41467-017-01452-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 09/19/2017] [Indexed: 12/12/2022] Open
Abstract
Many tip-growing cells are capable of responding to guidance cues, during which cells precisely steer their growth toward the source of guidance signals. Though several players in signal perception have been identified, little is known about the downstream signaling that controls growth direction during guidance. Here, using combined modeling and experimental studies, we demonstrate that the growth guidance of Arabidopsis pollen tubes is regulated by the signaling network that controls tip growth. Tip-localized exocytosis plays a key role in this network by integrating guidance signals with the ROP1 Rho GTPase signaling and coordinating intracellular signaling with cell wall mechanics. This model reproduces the high robustness and responsiveness of pollen tube guidance and explains the connection between guidance efficiency and the parameters of the tip growth system. Hence, our findings establish an exocytosis-coordinated mechanism underlying the cellular pathfinding guided by signal gradients and the mechanistic linkage between tip growth and guidance.
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Affiliation(s)
- Nan Luo
- Horticultural Biology and Metabolomics Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
- Department of Botany and Plant Sciences, Institute of Integrated Genome Biology, University of California, Riverside, CA, 92521, USA
| | - An Yan
- Department of Botany and Plant Sciences, Institute of Integrated Genome Biology, University of California, Riverside, CA, 92521, USA
| | - Gang Liu
- Department of Botany and Plant Sciences, Institute of Integrated Genome Biology, University of California, Riverside, CA, 92521, USA
| | - Jingzhe Guo
- Horticultural Biology and Metabolomics Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China
- Department of Botany and Plant Sciences, Institute of Integrated Genome Biology, University of California, Riverside, CA, 92521, USA
| | - Duoyan Rong
- Department of Botany and Plant Sciences, Institute of Integrated Genome Biology, University of California, Riverside, CA, 92521, USA
| | - Masahiro M Kanaoka
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Zhen Xiao
- Department of Botany and Plant Sciences, Institute of Integrated Genome Biology, University of California, Riverside, CA, 92521, USA
- Department of Statistics, University of California, Riverside, CA, 92521, USA
| | - Guanshui Xu
- Department of Mechanical Engineering, University of California, Riverside, CA, 92521, USA
| | - Tetsuya Higashiyama
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
- Institute of Transformative Bio-Molecules (WPI-ITbM), Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601, Japan
| | - Xinping Cui
- Department of Botany and Plant Sciences, Institute of Integrated Genome Biology, University of California, Riverside, CA, 92521, USA
- Department of Statistics, University of California, Riverside, CA, 92521, USA
| | - Zhenbiao Yang
- Horticultural Biology and Metabolomics Center, Haixia Institute of Science and Technology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China.
- Department of Botany and Plant Sciences, Institute of Integrated Genome Biology, University of California, Riverside, CA, 92521, USA.
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31
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Chang F. Forces that shape fission yeast cells. Mol Biol Cell 2017; 28:1819-1824. [PMID: 28684607 PMCID: PMC5541833 DOI: 10.1091/mbc.e16-09-0671] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 04/18/2017] [Accepted: 04/18/2017] [Indexed: 11/11/2022] Open
Abstract
One of the major challenges of modern cell biology is to understand how cells are assembled from nanoscale components into micrometer-scale entities with a specific size and shape. Here I describe how our quest to understand the morphogenesis of the fission yeast Schizosaccharomyces pombe drove us to investigate cellular mechanics. These studies build on the view that cell shape arises from the physical properties of an elastic cell wall inflated by internal turgor pressure. Consideration of cellular mechanics provides new insights into not only mechanisms responsible for cell-shape determination and growth, but also cellular processes such as cytokinesis and endocytosis. Studies in yeast can help to illuminate approaches and mechanisms to study the mechanobiology of the cell surface in other cell types, including animal cells.
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Affiliation(s)
- Fred Chang
- Department of Cell and Tissue Biology, University of California, San Francisco, San Francisco, CA 94143
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32
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Abstract
A conserved molecular machinery centered on the Cdc42 GTPase regulates cell polarity in diverse organisms. Here we review findings from budding and fission yeasts that reveal both a conserved core polarity circuit and several adaptations that each organism exploits to fulfill the needs of its lifestyle. The core circuit involves positive feedback by local activation of Cdc42 to generate a cluster of concentrated GTP-Cdc42 at the membrane. Species-specific pathways regulate the timing of polarization during the cell cycle, as well as the location and number of polarity sites.
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Affiliation(s)
- Jian-Geng Chiou
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710;
| | - Mohan K Balasubramanian
- Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Daniel J Lew
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710;
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33
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Rowghanian P, Campàs O. Non-equilibrium Membrane Homeostasis in Expanding Cellular Domains. Biophys J 2017; 113:132-137. [PMID: 28700911 DOI: 10.1016/j.bpj.2017.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 05/19/2017] [Accepted: 06/02/2017] [Indexed: 01/01/2023] Open
Abstract
Many cell behaviors involve cell-shape transformations that impose considerable changes in the cell's surface area, requiring a constant adaptation of the cell's plasma membrane area to prevent cell lysis. Here, we theoretically describe the interplay between the plasma membrane dynamics and a physically connected cell cortex or wall, accounting for spatial variations in membrane recycling and tension. In-plane membrane net flows result naturally from these dynamics and, in the presence of an expanding cell cortex or wall, regions of converging or diverging flow patterns emerge. These flow patterns can potentially explain the spatial localization/segregation of membrane proteins in processes such as cell polarization. We also identify the relevant parameters that control membrane homeostasis and derive the range of parameters for which homeostatic states exist.
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Affiliation(s)
- P Rowghanian
- Department of Mechanical Engineering and California NanoSystems Institute, University of California, Santa Barbara, Santa Barbara, California
| | - O Campàs
- Department of Mechanical Engineering and California NanoSystems Institute, University of California, Santa Barbara, Santa Barbara, California.
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34
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Jia F, Ben Amar M, Billoud B, Charrier B. Morphoelasticity in the development of brown alga Ectocarpus siliculosus: from cell rounding to branching. J R Soc Interface 2017; 14:20160596. [PMID: 28228537 PMCID: PMC5332559 DOI: 10.1098/rsif.2016.0596] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 01/27/2017] [Indexed: 11/29/2022] Open
Abstract
A biomechanical model is proposed for the growth of the brown alga Ectocarpus siliculosus Featuring ramified uniseriate filaments, this alga has two modes of growth: apical growth and intercalary growth with branching. Apical growth occurs upon the mitosis of a young cell at one extremity and leads to a new tip cell followed by a cylindrical cell, whereas branching mainly occurs when a cylindrical cell becomes rounded and swells, forming a spherical cell. Given the continuous interplay between cell growth and swelling, a poroelastic model combining osmotic pressure and volumetric growth is considered for the whole cell, cytoplasm and cell wall. The model recovers the morphogenetic transformations of mature cells: transformation of a cylindrical shape into spherical shape with a volumetric increase, and then lateral branching. Our simulations show that the poro-elastic model, including the Mooney-Rivlin approach for hyper-elastic materials, can correctly reproduce the observations. In particular, branching appears to be a plasticity effect due to the high level of tension created after the increase in volume of mature cells.
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Affiliation(s)
- Fei Jia
- School of Manufacturing Science and Engineering, Southwest University of Science and Technology, Sichuan 621010, People's Republic of China
| | - Martine Ben Amar
- Laboratoire de Physique Statistique, Ecole Normale Supérieure, PSL Research University, Sorbonne Universités UPMC Univ Paris 06, CNRS, 24 rue Lhomond, 75005 Paris, France
- Institut Universitaire de Cancérologie, Faculté de médecine, Université Pierre et Marie Curie-Paris 6, 91 Bd de l'Hôpital, 75013 Paris, France
| | - Bernard Billoud
- UMR8227 CNRS-UPMC, Station Biologique, Place George Teissier, 29680 Roscoff, France
| | - Bénédicte Charrier
- UMR8227 CNRS-UPMC, Station Biologique, Place George Teissier, 29680 Roscoff, France
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35
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Sveiczer Á, Horváth A. How do fission yeast cells grow and connect growth to the mitotic cycle? Curr Genet 2016; 63:165-173. [DOI: 10.1007/s00294-016-0632-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Accepted: 07/09/2016] [Indexed: 01/30/2023]
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36
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Role and organization of the actin cytoskeleton during cell-cell fusion. Semin Cell Dev Biol 2016; 60:121-126. [PMID: 27476112 DOI: 10.1016/j.semcdb.2016.07.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 07/25/2016] [Accepted: 07/26/2016] [Indexed: 11/23/2022]
Abstract
Cell-cell fusion is a ubiquitous process that underlies fertilization and development of eukaryotes. This process requires fusogenic machineries to promote plasma membrane merging, and also relies on the organization of dedicated sub-cortical cytoskeletal assemblies. This review describes the role of actin structures, so called actin fusion foci, essential for the fusion of two distinct cell types: Drosophila myoblast cells, which fuse to form myotubes, and sexually differentiated cells of the fission yeast Schizosaccharomyces pombe, which fuse to form a zygote. I describe the respective composition and organization of the two structures, discuss their proposed role in promoting plasma membrane apposition, and consider the universality of similar structures for cell-cell fusion.
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37
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Martin-Urdiroz M, Deeks MJ, Horton CG, Dawe HR, Jourdain I. The Exocyst Complex in Health and Disease. Front Cell Dev Biol 2016; 4:24. [PMID: 27148529 PMCID: PMC4828438 DOI: 10.3389/fcell.2016.00024] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 03/11/2016] [Indexed: 01/23/2023] Open
Abstract
Exocytosis involves the fusion of intracellular secretory vesicles with the plasma membrane, thereby delivering integral membrane proteins to the cell surface and releasing material into the extracellular space. Importantly, exocytosis also provides a source of lipid moieties for membrane extension. The tethering of the secretory vesicle before docking and fusion with the plasma membrane is mediated by the exocyst complex, an evolutionary conserved octameric complex of proteins. Recent findings indicate that the exocyst complex also takes part in other intra-cellular processes besides secretion. These various functions seem to converge toward defining a direction of membrane growth in a range of systems from fungi to plants and from neurons to cilia. In this review we summarize the current knowledge of exocyst function in cell polarity, signaling and cell-cell communication and discuss implications for plant and animal health and disease.
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Affiliation(s)
| | - Michael J Deeks
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Connor G Horton
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Helen R Dawe
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
| | - Isabelle Jourdain
- Biosciences, College of Life and Environmental Sciences, University of Exeter Exeter, UK
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38
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Revilla-Guarinos MT, Martín-García R, Villar-Tajadura MA, Estravís M, Coll PM, Pérez P. Rga6 is a Fission Yeast Rho GAP Involved in Cdc42 Regulation of Polarized Growth. Mol Biol Cell 2016; 27:mbc.E15-12-0818. [PMID: 26960792 PMCID: PMC4850039 DOI: 10.1091/mbc.e15-12-0818] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Revised: 03/03/2016] [Accepted: 03/04/2016] [Indexed: 11/15/2022] Open
Abstract
Active Cdc42 is essential for the establishment of polarized growth. This GTPase is negatively regulated by the GTPase-activating proteins (GAPs), which are important for the spatial specificity of Cdc42 function. Rga4 is the only GAP described as negative regulator of fission yeast Cdc42. We report here that Rga6 is another fission yeast Cdc42 GAP which shares some functions with Rga4. Cells lacking Rga6 are viable but slightly shorter and broader than wild type, and cells lacking Rga6 and Rga4 simultaneously are rounded. In these cells, active Cdc42 is observed all around the membrane. These additive effects indicate that both GAPs collaborate in the spatial regulation of active Cdc42. Rga6 localizes to the plasma membrane forming clusters different from those formed by Rga4. A polybasic region at the Rga6 C-terminus is responsible for its membrane localization. Rga6-GFP fluorescence decreases considerably at the growing tips, and this decrease is dependent on the actin cables. Notably, in the absence of Rga6 the amplitude of active Cdc42 oscillations at the tips decreases, and less GTP-Cdc42 accumulates at the new end of the cells. We propose here that Rga6 collaborates with Rga4 to spatially restrict active Cdc42 at the cell tips and maintain cell dimensions.
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Affiliation(s)
- M Teresa Revilla-Guarinos
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) / Departamento de Microbiología y Genética, Universidad de Salamanca. Salamanca, Spain
| | - Rebeca Martín-García
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) / Departamento de Microbiología y Genética, Universidad de Salamanca. Salamanca, Spain
| | - M Antonia Villar-Tajadura
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) / Departamento de Microbiología y Genética, Universidad de Salamanca. Salamanca, Spain
| | - Miguel Estravís
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) / Departamento de Microbiología y Genética, Universidad de Salamanca. Salamanca, Spain
| | - Pedro M Coll
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) / Departamento de Microbiología y Genética, Universidad de Salamanca. Salamanca, Spain
| | - Pilar Pérez
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC) / Departamento de Microbiología y Genética, Universidad de Salamanca. Salamanca, Spain
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39
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Martín-García R, Santos B. The price of independence: cell separation in fission yeast. World J Microbiol Biotechnol 2016; 32:65. [PMID: 26931605 DOI: 10.1007/s11274-016-2021-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 01/29/2016] [Indexed: 12/28/2022]
Abstract
The ultimate goal of cell division is to give rise to two viable independent daughter cells. A tight spatial and temporal regulation between chromosome segregation and cytokinesis ensures the viability of the daughter cells. Schizosaccharomyces pombe, commonly known as fission yeast, has become a leading model organism for studying essential and conserved mechanisms of the eukaryotic cell division process. Like many other eukaryotic cells it divides by binary fission and the cleavage furrow undergoes ingression due to the contraction of an actomyosin ring. In contrast to mammalian cells, yeasts as cell-walled organisms, also need to form a division septum made of cell wall material to complete the process of cytokinesis. The division septum is deposited behind the constricting ring and it will constitute the new ends of the daughter cells. Cell separation also involves cell wall degradation and this process should be precisely regulated to avoid cell lysis. In this review, we will give a brief overview of the whole cytokinesis process in fission yeast, from the positioning and assembly of the contractile ring to the final step of cell separation, and the problems generated when these processes are not precise.
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Affiliation(s)
- Rebeca Martín-García
- Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas, University of Salamanca, 37007, Salamanca, Spain
| | - Beatriz Santos
- Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas, University of Salamanca, 37007, Salamanca, Spain.
- Departamento de Microbiología y Genética, University of Salamanca, 37007, Salamanca, Spain.
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