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Deinum EE, Jacobs B. Rho of Plants patterning: linking mathematical models and molecular diversity. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:1274-1288. [PMID: 37962515 PMCID: PMC10901209 DOI: 10.1093/jxb/erad447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 11/08/2023] [Indexed: 11/15/2023]
Abstract
ROPs (Rho of Plants) are plant specific small GTPases involved in many membrane patterning processes and play important roles in the establishment and communication of cell polarity. These small GTPases can produce a wide variety of patterns, ranging from a single cluster in tip-growing root hairs and pollen tubes to an oriented stripe pattern controlling protoxylem cell wall deposition. For an understanding of what controls these various patterns, models are indispensable. Consequently, many modelling studies on small GTPase patterning exist, often focusing on yeast or animal cells. Multiple patterns occurring in plants, however, require the stable co-existence of multiple active ROP clusters, which does not occur with the most common yeast/animal models. The possibility of such patterns critically depends on the precise model formulation. Additionally, different small GTPases are usually treated interchangeably in models, even though plants possess two types of ROPs with distinct molecular properties, one of which is unique to plants. Furthermore, the shape and even the type of ROP patterns may be affected by the cortical cytoskeleton, and cortex composition and anisotropy differ dramatically between plants and animals. Here, we review insights into ROP patterning from modelling efforts across kingdoms, as well as some outstanding questions arising from these models and recent experimental findings.
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Affiliation(s)
- Eva E Deinum
- Mathematical and Statistical Methods (Biometris), Plant Science Group, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Bas Jacobs
- Mathematical and Statistical Methods (Biometris), Plant Science Group, Wageningen University, 6708 PB Wageningen, The Netherlands
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2
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Murshed M, Wei D, Gu Y, Wang J. Simulation of microtubule-cytoplasm interaction revealed the importance of fluid dynamics in determining the organization of microtubules. PLANT DIRECT 2023; 7:e505. [PMID: 37502315 PMCID: PMC10368657 DOI: 10.1002/pld3.505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 03/24/2023] [Accepted: 05/30/2023] [Indexed: 07/29/2023]
Abstract
Although microtubules in plant cells have been extensively studied, the mechanisms that regulate the spatial organization of microtubules are poorly understood. We hypothesize that the interaction between microtubules and cytoplasmic flow plays an important role in the assembly and orientation of microtubules. To test this hypothesis, we developed a new computational modeling framework for microtubules based on theory and methods from the fluid-structure interaction. We employed the immersed boundary method to track the movement of microtubules in cytoplasmic flow. We also incorporated details of the encounter dynamics when two microtubules collide with each other. We verified our computational model through several numerical tests before applying it to the simulation of the microtubule-cytoplasm interaction in a growing plant cell. Our computational investigation demonstrated that microtubules are primarily oriented in the direction orthogonal to the axis of cell elongation. We validated the simulation results through a comparison with the measurement from laboratory experiments. We found that our computational model, with further calibration, was capable of generating microtubule orientation patterns that were qualitatively and quantitatively consistent with the experimental results. The computational model proposed in this study can be naturally extended to many other cellular systems that involve the interaction between microstructures and the intracellular fluid.
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Affiliation(s)
- Mohammad Murshed
- Department of MathematicsUniversity of Tennessee at ChattanoogaChattanoogaTennesseeUSA
| | - Donghui Wei
- Department of Biochemistry and Molecular BiologyPennsylvania State UniversityState CollegePennsylvaniaUSA
| | - Ying Gu
- Department of Biochemistry and Molecular BiologyPennsylvania State UniversityState CollegePennsylvaniaUSA
| | - Jin Wang
- Department of MathematicsUniversity of Tennessee at ChattanoogaChattanoogaTennesseeUSA
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3
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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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4
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Zhou Q, Fu Z, Li M, Shen Q, Sun C, Feng Y, Liu Y, Jiang J, Qin T, Mao T, Hearne SJ, Wang G, Tang J. Maize tubulin folding cofactor B is required for cell division and cell growth through modulating microtubule homeostasis. THE NEW PHYTOLOGIST 2023. [PMID: 36843261 DOI: 10.1111/nph.18839] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 02/20/2023] [Indexed: 06/18/2023]
Abstract
Tubulin folding cofactors (TFCs) are required for tubulin folding, α/β tubulin heterodimer formation, and microtubule (MT) dynamics in yeast and mammals. However, the functions of their plant counterparts remain to be characterized. We identified a natural maize crumpled kernel mutant, crk2, which exhibits reductions in endosperm cell number and size, as well as embryo/seedling lethality. Map-based cloning and functional complementation confirmed that ZmTFCB is causal for the mutation. ZmTFCB is targeted mainly to the cytosol. It facilitates α-tubulin folding and heterodimer formation through sequential interactions with the cytosolic chaperonin-containing TCP-1 ε subunit ZmCCT5 and ZmTFCE, thus affecting the organization of both the spindle and phragmoplast MT array and the cortical MT polymerization and array formation, which consequently mediated cell division and cell growth. We detected a physical association between ZmTFCB and the maize MT plus-end binding protein END-BINDING1 (ZmEB1), indicating that ZmTFCB1 may modulate MT dynamics by sequestering ZmEB1. Our data demonstrate that ZmTFCB is required for cell division and cell growth through modulating MT homeostasis, an evolutionarily conserved machinery with some species-specific divergence.
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Affiliation(s)
- Qingqian Zhou
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Zhiyuan Fu
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Mengyuan Li
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Qingwen Shen
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Canran Sun
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Yijian Feng
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Yang Liu
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Jianjun Jiang
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Tao Qin
- College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Tonglin Mao
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Sarah Jane Hearne
- CIMMYT, KM 45 Carretera Mexico-Veracruz, El Batan, Texcoco, Estado de México, 56237, Mexico
| | - Guifeng Wang
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
| | - Jihua Tang
- National Key Laboratory of Wheat and Maize Crops Science/Collaborative Innovation Center of Henan Grain Crops/College of Agronomy, Henan Agricultural University, Zhengzhou, 450046, China
- The Shennong Laboratory, Zhengzhou, Henan, 450002, China
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5
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Autran D, Bassel GW, Chae E, Ezer D, Ferjani A, Fleck C, Hamant O, Hartmann FP, Jiao Y, Johnston IG, Kwiatkowska D, Lim BL, Mahönen AP, Morris RJ, Mulder BM, Nakayama N, Sozzani R, Strader LC, ten Tusscher K, Ueda M, Wolf S. What is quantitative plant biology? QUANTITATIVE PLANT BIOLOGY 2021; 2:e10. [PMID: 37077212 PMCID: PMC10095877 DOI: 10.1017/qpb.2021.8] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2020] [Revised: 04/07/2021] [Accepted: 04/07/2021] [Indexed: 05/03/2023]
Abstract
Quantitative plant biology is an interdisciplinary field that builds on a long history of biomathematics and biophysics. Today, thanks to high spatiotemporal resolution tools and computational modelling, it sets a new standard in plant science. Acquired data, whether molecular, geometric or mechanical, are quantified, statistically assessed and integrated at multiple scales and across fields. They feed testable predictions that, in turn, guide further experimental tests. Quantitative features such as variability, noise, robustness, delays or feedback loops are included to account for the inner dynamics of plants and their interactions with the environment. Here, we present the main features of this ongoing revolution, through new questions around signalling networks, tissue topology, shape plasticity, biomechanics, bioenergetics, ecology and engineering. In the end, quantitative plant biology allows us to question and better understand our interactions with plants. In turn, this field opens the door to transdisciplinary projects with the society, notably through citizen science.
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Affiliation(s)
- Daphné Autran
- DIADE, University of Montpellier, IRD, CIRAD, Montpellier, France
| | - George W. Bassel
- School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Eunyoung Chae
- Department of Biological Sciences, National University of Singapore, Singapore, Singapore
| | - Daphne Ezer
- The Alan Turing Institute, London, United Kingdom
- Department of Statistics, University of Warwick, Coventry, United Kingdom
- Department of Biology, University of York, York, United Kingdom
| | - Ali Ferjani
- Department of Biology, Tokyo Gakugei University, Tokyo, Japan
| | - Christian Fleck
- Freiburg Center for Data Analysis and Modeling (FDM), University of Freiburg, Breisgau, Germany
| | - Olivier Hamant
- Laboratoire de Reproduction et Développement des Plantes, École normale supérieure (ENS) de Lyon, Université Claude Bernard Lyon (UCBL), Lyon, France
- Institut national de recherche pour l’agriculture, l’alimentation et l’environnement (INRAE), CNRS, Université de Lyon, Lyon, France
- Author for correspondence: O. Hamant and A. P. Mahönen, E-mail: ,
| | | | - Yuling Jiao
- State Key Laboratory of Plant Genomics and National Center for Plant Gene Research (Beijing), Institute of Genetics and Developmental Biology, The Innovative Academy of Seed Design, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | | | - Dorota Kwiatkowska
- Institute of Biology, Biotechnology and Environment Protection, Faculty of Natural Sciences, University of Silesia in Katowice, Katowice, Poland
| | - Boon L. Lim
- School of Biological Sciences, University of Hong Kong, Hong Kong, China
| | - Ari Pekka Mahönen
- Institute of Biotechnology, HiLIFE, University of Helsinki, Helsinki, Finland
- Organismal and Evolutionary Biology Research Programme, Faculty of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland
- Viikki Plant Science Centre, University of Helsinki, Helsinki, Finland
| | - Richard J. Morris
- Computational and Systems Biology, John Innes Centre, Norwich, United Kingdom
| | - Bela M. Mulder
- Department of Living Matter, Institute AMOLF, Amsterdam, The Netherlands
| | - Naomi Nakayama
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Ross Sozzani
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, North CarolinaUSA
| | - Lucia C. Strader
- Department of Biology, Duke University, Durham, North Carolina, USA
- NSF Science and Technology Center for Engineering Mechanobiology, Department of Biology, Washington University in St. Louis, St. Louis, MissouriUSA
| | - Kirsten ten Tusscher
- Theoretical Biology, Department of Biology, Utrecht University, Utrecht, The Netherlands
| | - Minako Ueda
- Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Sebastian Wolf
- Centre for Organismal Studies (COS) Heidelberg, Heidelberg University, Heidelberg, Germany
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6
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Jacobs B, Molenaar J, Deinum EE. Robust banded protoxylem pattern formation through microtubule-based directional ROP diffusion restriction. J Theor Biol 2020; 502:110351. [PMID: 32505828 DOI: 10.1016/j.jtbi.2020.110351] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 04/07/2020] [Accepted: 05/27/2020] [Indexed: 12/28/2022]
Abstract
In plant vascular tissue development, different cell wall patterns are formed, offering different mechanical properties optimised for different growth stages. Critical in these patterning processes are Rho of Plants (ROP) proteins, a class of evolutionarily conserved small GTPase proteins responsible for local membrane domain formation in many organisms. While te spotted metaxylem pattern can easily be understood as a result of a Turing-style reaction-diffusion mechanism, it remains an open question how the consistent orientation of evenly spaced bands and spirals as found in protoxylem is achieved. We hypothesise that this orientation results from an interaction between ROPs and an array of transversely oriented cortical microtubules that acts as a directional diffusion barrier. Here, we explore this hypothesis using partial differential equation models with anisotropic ROP diffusion and show that a horizontal microtubule array acting as a vertical diffusion barrier to active ROP can yield a horizontally banded ROP pattern. We then study the underlying mechanism in more detail, finding that it can only orient curved pattern features but not straight lines. This implies that, once formed, banded and spiral patterns cannot be reoriented by this mechanism. Finally, we observe that ROPs and microtubules together only form ultimately static patterns if the interaction is implemented with sufficient biological realism.
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Affiliation(s)
- Bas Jacobs
- Biometris, Department for Mathematical and Statistical Methods, Wageningen University, Wageningen, The Netherlands
| | - Jaap Molenaar
- Biometris, Department for Mathematical and Statistical Methods, Wageningen University, Wageningen, The Netherlands
| | - Eva E Deinum
- Biometris, Department for Mathematical and Statistical Methods, Wageningen University, Wageningen, The Netherlands.
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7
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Zhou R, Liu H, Ju T, Dixit R. Quantifying the polymerization dynamics of plant cortical microtubules using kymograph analysis. Methods Cell Biol 2020; 160:281-293. [PMID: 32896322 DOI: 10.1016/bs.mcb.2020.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The plant cortical microtubule array is a dynamic structure that confers cell shape and enables plants to alter their growth and development in response to internal and external cues. Cells use a variety of microtubule regulatory proteins to spatially and temporally modulate the intrinsic polymerization dynamics of cortical microtubules to arrange them into specific configurations and to reshape arrays to adapt to changing conditions. To obtain mechanistic insight into how particular microtubule regulatory proteins mediate the dynamic (re)structuring of cortical microtubule arrays, we need to measure their effect on the dynamics of cortical microtubules. In this chapter, we describe new ImageJ plugins to generate kymographs from time-lapse images and to analyze them to measure the parameters that quantitatively describe cortical microtubule dynamics.
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Affiliation(s)
- Rudy Zhou
- Department of Computer Science and Engineering, Washington University in St. Louis, St. Louis, MO, United States; Department of Biology and Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, United States
| | - Han Liu
- Department of Computer Science and Engineering, Washington University in St. Louis, St. Louis, MO, United States; Department of Biology and Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, United States
| | - Tao Ju
- Department of Computer Science and Engineering, Washington University in St. Louis, St. Louis, MO, United States.
| | - Ram Dixit
- Department of Biology and Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, United States.
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8
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Ovečka M, Luptovčiak I, Komis G, Šamajová O, Samakovli D, Šamaj J. Spatiotemporal Pattern of Ectopic Cell Divisions Contribute to Mis-Shaped Phenotype of Primary and Lateral Roots of katanin1 Mutant. FRONTIERS IN PLANT SCIENCE 2020; 11:734. [PMID: 32582258 PMCID: PMC7296145 DOI: 10.3389/fpls.2020.00734] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 05/07/2020] [Indexed: 05/04/2023]
Abstract
Pattern formation, cell proliferation, and directional cell growth, are driving factors of plant organ shape, size, and overall vegetative development. The establishment of vegetative morphogenesis strongly depends on spatiotemporal control and synchronization of formative and proliferative cell division patterns. In this context, the progression of cell division and the regulation of cell division plane orientation are defined by molecular mechanisms converging to the proper positioning and temporal reorganization of microtubule arrays such as the preprophase microtubule band, the mitotic spindle and the cytokinetic phragmoplast. By focusing on the tractable example of primary root development and lateral root emergence in Arabidopsis thaliana, genetic studies have highlighted the importance of mechanisms underlying microtubule reorganization in the establishment of the root system. In this regard, severe alterations of root growth, and development found in extensively studied katanin1 mutants of A. thaliana (fra2, lue1, and ktn1-2), were previously attributed to defective rearrangements of cortical microtubules and aberrant cell division plane reorientation. How KATANIN1-mediated microtubule severing contributes to tissue patterning and organ morphogenesis, ultimately leading to anisotropy in microtubule organization is a trending topic under vigorous investigation. Here we addressed this issue during root development, using advanced light-sheet fluorescence microscopy (LSFM) and long-term imaging of ktn1-2 mutant expressing the GFP-TUA6 microtubule marker. This method allowed spatial and temporal monitoring of cell division patterns in growing roots. Analysis of acquired multidimensional data sets revealed the occurrence of ectopic cell divisions in various tissues including the calyptrogen and the protoxylem of the main root, as well as in lateral root primordia. Notably the ktn1-2 mutant exhibited excessive longitudinal cell divisions (parallel to the root axis) at ectopic positions. This suggested that changes in the cell division pattern and the occurrence of ectopic cell divisions contributed significantly to pleiotropic root phenotypes of ktn1-2 mutant. LSFM provided evidence that KATANIN1 is required for the spatiotemporal control of cell divisions and establishment of tissue patterns in living A. thaliana roots.
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9
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Schneider R, Sampathkumar A, Persson S. Quantification of Cytoskeletal Dynamics in Time-Lapse Recordings. ACTA ACUST UNITED AC 2019; 4:e20091. [PMID: 31091014 DOI: 10.1002/cppb.20091] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The cytoskeleton is key to many essential processes in a plant cell, e.g., growth, division, and defense. Contrary to what "skeleton" implies, the cytoskeleton is highly dynamic, and is able to re-organize itself continuously. The advent of live-cell microscopy and the development of genetically encoded fluorophores enabled detailed observation of the organization and dynamics of the cytoskeleton. Despite the biological importance of the cytoskeletal dynamics, quantitative analyses remain laborious endeavors that only a handful of research teams regularly conduct. With this protocol, we provide a standardized step-by-step guide to analyze the dynamics of microtubules. We provide example data and code for post-processing in Fiji that enables researchers to modify and adapt the routine to their needs. More such tools are needed to quantitatively assess the cytoskeleton and thus to better understand cell biology. © 2019 by John Wiley & Sons, Inc.
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Affiliation(s)
- René Schneider
- Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Arun Sampathkumar
- Max Planck Institute of Molecular Plant Physiology, Potsdam, Germany
| | - Staffan Persson
- School of Biosciences, University of Melbourne, Parkville, Victoria, Australia
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10
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Lindeboom JJ, Nakamura M, Saltini M, Hibbel A, Walia A, Ketelaar T, Emons AMC, Sedbrook JC, Kirik V, Mulder BM, Ehrhardt DW. CLASP stabilization of plus ends created by severing promotes microtubule creation and reorientation. J Cell Biol 2019; 218:190-205. [PMID: 30377221 PMCID: PMC6314540 DOI: 10.1083/jcb.201805047] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 09/04/2018] [Accepted: 10/17/2018] [Indexed: 12/23/2022] Open
Abstract
Central to the building and reorganizing cytoskeletal arrays is creation of new polymers. Although nucleation has been the major focus of study for microtubule generation, severing has been proposed as an alternative mechanism to create new polymers, a mechanism recently shown to drive the reorientation of cortical arrays of higher plants in response to blue light perception. Severing produces new plus ends behind the stabilizing GTP-cap. An important and unanswered question is how these ends are stabilized in vivo to promote net microtubule generation. Here we identify the conserved protein CLASP as a potent stabilizer of new plus ends created by katanin severing in plant cells. Clasp mutants are defective in cortical array reorientation. In these mutants, both rescue of shrinking plus ends and the stabilization of plus ends immediately after severing are reduced. Computational modeling reveals that it is the specific stabilization of severed ends that best explains CLASP's function in promoting microtubule amplification by severing and array reorientation.
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Affiliation(s)
- Jelmer J Lindeboom
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA
- Laboratory of Cell Biology, Wageningen University, Wageningen, Netherlands
| | - Masayoshi Nakamura
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA
- Institute of Transformative Bio-Molecules, Nagoya University, Nagoya, Japan
| | | | - Anneke Hibbel
- Laboratory of Cell Biology, Wageningen University, Wageningen, Netherlands
| | - Ankit Walia
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA
- Sainsbury Laboratory, University of Cambridge, Cambridge, UK
| | - Tijs Ketelaar
- Laboratory of Cell Biology, Wageningen University, Wageningen, Netherlands
| | - Anne Mie C Emons
- Laboratory of Cell Biology, Wageningen University, Wageningen, Netherlands
- Institute AMOLF, Amsterdam, Netherlands
| | - John C Sedbrook
- School of Biological Sciences, Illinois State University, Normal, IL
| | - Viktor Kirik
- School of Biological Sciences, Illinois State University, Normal, IL
| | - Bela M Mulder
- Laboratory of Cell Biology, Wageningen University, Wageningen, Netherlands
- Institute AMOLF, Amsterdam, Netherlands
| | - David W Ehrhardt
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA
- Department of Biology, Stanford University, Stanford, CA
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11
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A Plausible Microtubule-Based Mechanism for Cell Division Orientation in Plant Embryogenesis. Curr Biol 2018; 28:3031-3043.e2. [PMID: 30245102 DOI: 10.1016/j.cub.2018.07.025] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 05/18/2018] [Accepted: 07/09/2018] [Indexed: 01/27/2023]
Abstract
Oriented cell divisions are significant in plant morphogenesis because plant cells are embedded in cell walls and cannot relocate. Cell divisions follow various regular orientations, but the underlying mechanisms have not been clarified. We propose that cell-shape-dependent self-organization of cortical microtubule arrays is able to provide a mechanism for determining planes of early tissue-generating divisions and may form the basis for robust control of cell division orientation in the embryo. To show this, we simulate microtubules on actual cell surface shapes, from which we derive a minimal set of three rules for proper array orientation. The first rule captures the effects of cell shape alone on microtubule organization, the second rule describes the regulation of microtubule stability at cell edges, and the third rule includes the differential effect of auxin on local microtubule stability. These rules generate early embryonic division plane orientations and potentially offer a framework for understanding patterned cell divisions in plant morphogenesis.
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12
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Chakrabortty B, Blilou I, Scheres B, Mulder BM. A computational framework for cortical microtubule dynamics in realistically shaped plant cells. PLoS Comput Biol 2018; 14:e1005959. [PMID: 29394250 PMCID: PMC5812663 DOI: 10.1371/journal.pcbi.1005959] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 02/14/2018] [Accepted: 01/05/2018] [Indexed: 01/07/2023] Open
Abstract
Plant morphogenesis is strongly dependent on the directional growth and the subsequent oriented division of individual cells. It has been shown that the plant cortical microtubule array plays a key role in controlling both these processes. This ordered structure emerges as the collective result of stochastic interactions between large numbers of dynamic microtubules. To elucidate this complex self-organization process a number of analytical and computational approaches to study the dynamics of cortical microtubules have been proposed. To date, however, these models have been restricted to two dimensional planes or geometrically simple surfaces in three dimensions, which strongly limits their applicability as plant cells display a wide variety of shapes. This limitation is even more acute, as both local as well as global geometrical features of cells are expected to influence the overall organization of the array. Here we describe a framework for efficiently simulating microtubule dynamics on triangulated approximations of arbitrary three dimensional surfaces. This allows the study of microtubule array organization on realistic cell surfaces obtained by segmentation of microscopic images. We validate the framework against expected or known results for the spherical and cubical geometry. We then use it to systematically study the individual contributions of global geometry, cell-edge induced catastrophes and cell-face induced stability to array organization in a cuboidal geometry. Finally, we apply our framework to analyze the highly non-trivial geometry of leaf pavement cells of Arabidopsis thaliana, Nicotiana benthamiana and Hedera helix. We show that our simulations can predict multiple features of the microtubule array structure in these cells, revealing, among others, strong constraints on the orientation of division planes.
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Affiliation(s)
- Bandan Chakrabortty
- Plant Developmental Biology, Wageningen University, Wageningen, The Netherlands
- Department of Living Matter, Institute AMOLF, Amsterdam, The Netherlands
| | - Ikram Blilou
- Laboratory of plant cell and developmental biology, King Abdullah University of Science and Technology, Thuwal, Kingdom of Saudi Arabia
| | - Ben Scheres
- Plant Developmental Biology, Wageningen University, Wageningen, The Netherlands
| | - Bela M. Mulder
- Department of Living Matter, Institute AMOLF, Amsterdam, The Netherlands
- Cell Biology, Wageningen University, Wageningen, The Netherlands
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13
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How selective severing by katanin promotes order in the plant cortical microtubule array. Proc Natl Acad Sci U S A 2017. [PMID: 28630321 DOI: 10.1073/pnas.1702650114] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Plant morphogenesis requires differential and often asymmetric growth. A key role in controlling anisotropic expansion of individual cells is played by the cortical microtubule array. Although highly organized, the array can nevertheless rapidly change in response to internal and external cues. Experiments have identified the microtubule-severing enzyme katanin as a central player in controlling the organizational state of the array. Katanin action is required both for normal alignment and the adaptation of array orientation to mechanical, environmental, and developmental stimuli. How katanin fulfills its controlling role, however, remains poorly understood. On the one hand, from a theoretical perspective, array ordering depends on the "weeding out" of discordant microtubules through frequent catastrophe-inducing collisions among microtubules. Severing would reduce average microtubule length and lifetime, and consequently weaken the driving force for alignment. On the other hand, it has been suggested that selective severing at microtubule crossovers could facilitate the removal of discordant microtubules. Here we show that this apparent conflict can be resolved by systematically dissecting the role of all of the relevant interactions in silico. This procedure allows the identification of the sufficient and necessary conditions for katanin to promote array alignment, stresses the critical importance of the experimentally observed selective severing of the "crossing" microtubule at crossovers, and reveals a hitherto not appreciated role for microtubule bundling. We show how understanding the underlying mechanism can aid with interpreting experimental results and designing future experiments.
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14
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Provart NJ, Alonso J, Assmann SM, Bergmann D, Brady SM, Brkljacic J, Browse J, Chapple C, Colot V, Cutler S, Dangl J, Ehrhardt D, Friesner JD, Frommer WB, Grotewold E, Meyerowitz E, Nemhauser J, Nordborg M, Pikaard C, Shanklin J, Somerville C, Stitt M, Torii KU, Waese J, Wagner D, McCourt P. 50 years of Arabidopsis research: highlights and future directions. THE NEW PHYTOLOGIST 2016; 209:921-44. [PMID: 26465351 DOI: 10.1111/nph.13687] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 08/24/2015] [Indexed: 05/14/2023]
Abstract
922 I. 922 II. 922 III. 925 IV. 925 V. 926 VI. 927 VII. 928 VIII. 929 IX. 930 X. 931 XI. 932 XII. 933 XIII. Natural variation and genome-wide association studies 934 XIV. 934 XV. 935 XVI. 936 XVII. 937 937 References 937 SUMMARY: The year 2014 marked the 25(th) International Conference on Arabidopsis Research. In the 50 yr since the first International Conference on Arabidopsis Research, held in 1965 in Göttingen, Germany, > 54 000 papers that mention Arabidopsis thaliana in the title, abstract or keywords have been published. We present herein a citational network analysis of these papers, and touch on some of the important discoveries in plant biology that have been made in this powerful model system, and highlight how these discoveries have then had an impact in crop species. We also look to the future, highlighting some outstanding questions that can be readily addressed in Arabidopsis. Topics that are discussed include Arabidopsis reverse genetic resources, stock centers, databases and online tools, cell biology, development, hormones, plant immunity, signaling in response to abiotic stress, transporters, biosynthesis of cells walls and macromolecules such as starch and lipids, epigenetics and epigenomics, genome-wide association studies and natural variation, gene regulatory networks, modeling and systems biology, and synthetic biology.
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Affiliation(s)
- Nicholas J Provart
- Department of Cell & Systems Biology/CAGEF, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Jose Alonso
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, 27695, USA
| | - Sarah M Assmann
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA
| | | | - Siobhan M Brady
- Department of Plant Biology, University of California, Davis, CA, 95616, USA
| | - Jelena Brkljacic
- Arabidopsis Biological Resource Center, The Ohio State University, Columbus, OH, 43210, USA
| | - John Browse
- Institute of Biological Chemistry, Washington State University, Pullman, WA, 99164, USA
| | - Clint Chapple
- Department of Biochemistry, Purdue University, West Lafayette, IN, 47907, USA
| | - Vincent Colot
- Departement de Biologie École Normale Supérieure, Biologie Moleculaire des Organismes Photosynthetiques, F-75230, Paris, France
| | - Sean Cutler
- Department of Botany and Plant Sciences, University of California, Riverside, CA, 92507, USA
| | - Jeff Dangl
- Department of Biology and Howard Hughes Medical Institute, Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - David Ehrhardt
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - Joanna D Friesner
- Department of Plant Biology, Agricultural Sustainability Institute, University of California, Davis, CA, 95616, USA
| | - Wolf B Frommer
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA, 94305, USA
| | - Erich Grotewold
- Center for Applied Plant Science, The Ohio State University, Columbus, OH, 43210, USA
| | - Elliot Meyerowitz
- Division of Biology and Biological Engineering and Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Jennifer Nemhauser
- Department of Biology, University of Washington, Seattle, WA, 98195, USA
| | - Magnus Nordborg
- Gregor Mendel Institute of Molecular Plant Biology, A-1030, Vienna, Austria
| | - Craig Pikaard
- Department of Biology, Indiana University, Bloomington, IN, 47405, USA
| | - John Shanklin
- Biology Department, Brookhaven National Laboratory, Upton, NY, 11973, USA
| | - Chris Somerville
- Energy Biosciences Institute, University of California, Berkeley, CA, 94704, USA
| | - Mark Stitt
- Metabolic Networks Department, Max Planck Institute for Molecular Plant Physiology, D-14476, Potsdam, Germany
| | - Keiko U Torii
- Department of Biology, University of Washington, Seattle, WA, 98195, USA
| | - Jamie Waese
- Department of Cell & Systems Biology/CAGEF, University of Toronto, Toronto, ON, M5S 3B2, Canada
| | - Doris Wagner
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Peter McCourt
- Department of Cell & Systems Biology/CAGEF, University of Toronto, Toronto, ON, M5S 3B2, Canada
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15
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Zhang HM, Talbot MJ, McCurdy DW, Patrick JW, Offler CE. Calcium-dependent depletion zones in the cortical microtubule array coincide with sites of, but do not regulate, wall ingrowth papillae deposition in epidermal transfer cells. JOURNAL OF EXPERIMENTAL BOTANY 2015; 66:6021-33. [PMID: 26136268 PMCID: PMC4566988 DOI: 10.1093/jxb/erv317] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Trans-differentiation to a transfer-cell morphology is characterized by the localized deposition of wall ingrowth papillae that protrude into the cytosol. Whether the cortical microtubule array directs wall ingrowth papillae formation was investigated using a Vicia faba cotyledon culture system in which their adaxial epidermal cells were spontaneously induced to trans-differentiate to transfer cells. During deposition of wall ingrowth papillae, the aligned cortical microtubule arrays in precursor epidermal cells were reorganized into a randomized array characterized by circular depletion zones. Concurrence of the temporal appearance, spatial pattern, and size of depletion zones and wall ingrowth papillae was consistent with each papilla occupying a depletion zone. Surprisingly, microtubules appeared not to regulate construction of wall ingrowth papillae, as neither depolymerization nor stabilization of cortical microtubules changed their deposition pattern or morphology. Moreover, the size and spatial pattern of depletion zones was unaltered when the formation of wall ingrowth papillae was blocked by inhibiting cellulose biosynthesis. In contrast, the depletion zones were absent when the cytosolic calcium plumes, responsible for directing wall ingrowth papillae formation, were blocked or dissipated. Thus, we conclude that the depletion zones within the cortical microtubule array result from localized depolymerization of microtubules initiated by elevated cytosolic Ca(2+) levels at loci where wall ingrowth papillae are deposited. The physiological significance of the depletion zones as a mechanism to accommodate the construction of wall ingrowth papillae without compromising maintenance of the plasma membrane-microtubule inter-relationship is discussed.
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Affiliation(s)
- Hui-ming Zhang
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Mark J Talbot
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia CSIRO Agriculture, Canberra, ACT 2601, Australia
| | - David W McCurdy
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - John W Patrick
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Christina E Offler
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
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16
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Abstract
In living cells, the architecture of the microtubule cytoskeleton is intimately linked to its function. The principles determining how microtubules arrange in space are, however, still not fully understood. Biochemical activities controlling microtubule nucleation and dynamics as well as mechanochemical activities exerted by molecular motors and the dynamic microtubules themselves are known to be critical for the correct spatial organization of the microtubule cytoskeleton. In vitro reconstitution approaches have revealed the morphogenetic properties of these activities in minimal systems. In most cases, such in vitro experiments were performed in experimental chambers of spatial dimensions that exceeded typical cell sizes by orders of magnitude. Here, we describe a method for the fluorescence microscopic study of the effects of spatial confinement on the self-organization of purified motors and microtubules that are encapsulated in micrometer-sized lipid-monolayered droplets emulsified in oil. In the future, this experimental setup can be extended in several ways. Additional proteins can be added, either to the lumen or to the boundary of the microcontainers, and the droplets can be transformed into liposomes. Such more complex in vitro reconstitutions would be another step closer to mimicking intracellular cytoskeleton organization.
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Affiliation(s)
- Hella Baumann
- London Research Institute, Cancer Research UK, London, UK
| | - Thomas Surrey
- London Research Institute, Cancer Research UK, London, UK
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17
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Liu Z, Persson S, Zhang Y. The connection of cytoskeletal network with plasma membrane and the cell wall. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2015; 57:330-40. [PMID: 25693826 PMCID: PMC4405036 DOI: 10.1111/jipb.12342] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 02/14/2015] [Indexed: 05/18/2023]
Abstract
The cell wall provides external support of the plant cells, while the cytoskeletons including the microtubules and the actin filaments constitute an internal framework. The cytoskeletons contribute to the cell wall biosynthesis by spatially and temporarily regulating the transportation and deposition of cell wall components. This tight control is achieved by the dynamic behavior of the cytoskeletons, but also through the tethering of these structures to the plasma membrane. This tethering may also extend beyond the plasma membrane and impact on the cell wall, possibly in the form of a feedback loop. In this review, we discuss the linking components between the cytoskeletons and the plasma membrane, and/or the cell wall. We also discuss the prospective roles of these components in cell wall biosynthesis and modifications, and aim to provide a platform for further studies in this field.
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Affiliation(s)
- Zengyu Liu
- Max-Planck Institute for Molecular Plant Physiology14476 Potsdam, Germany
| | - Staffan Persson
- Max-Planck Institute for Molecular Plant Physiology14476 Potsdam, Germany
- ARC Centre of Excellence in Plant Cell Walls, School of Botany, University of MelbourneParkville, 3010, Victoria, Australia
| | - Yi Zhang
- Max-Planck Institute for Molecular Plant Physiology14476 Potsdam, Germany
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18
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Abstract
Microtubules (MTs) are highly conserved polar polymers that are key elements of the eukaryotic cytoskeleton and are essential for various cell functions. αβ-tubulin, a heterodimer containing one structural GTP and one hydrolysable and exchangeable GTP, is the building block of MTs and is formed by the sequential action of several molecular chaperones. GTP hydrolysis in the MT lattice is mechanistically coupled with MT growth, thus giving MTs a metastable and dynamic nature. MTs adopt several distinct higher-order organizations that function in cell division and cell morphogenesis. Small molecular weight compounds that bind tubulin are used as herbicides and as research tools to investigate MT functions in plant cells. The de novo formation of MTs in cells requires conserved γ-tubulin-containing complexes and targeting/activating regulatory proteins that contribute to the geometry of MT arrays. Various MT regulators and tubulin modifications control the dynamics and organization of MTs throughout the cell cycle and in response to developmental and environmental cues. Signaling pathways that converge on the regulation of versatile MT functions are being characterized.
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Affiliation(s)
- Takashi Hashimoto
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Takayama 8916-5, Ikoma, Nara 630-0192, Japan
- Address correspondence to
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19
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The Effect of Anisotropic Microtubule-Bound Nucleations on Ordering in the Plant Cortical Array. Bull Math Biol 2014; 76:2907-22. [DOI: 10.1007/s11538-014-0039-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 10/13/2014] [Indexed: 11/26/2022]
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20
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Walia A, Nakamura M, Moss D, Kirik V, Hashimoto T, Ehrhardt DW. GCP-WD mediates γ-TuRC recruitment and the geometry of microtubule nucleation in interphase arrays of Arabidopsis. Curr Biol 2014; 24:2548-55. [PMID: 25438942 DOI: 10.1016/j.cub.2014.09.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2014] [Revised: 07/26/2014] [Accepted: 09/02/2014] [Indexed: 11/30/2022]
Abstract
Many differentiated animal cells, and all higher plant cells, build interphase microtubule arrays of specific architectures without benefit of a central organizer, such as a centrosome, to control the location and geometry of microtubule nucleation. These acentrosomal arrays support essential cell functions such as morphogenesis, but the mechanisms by which the new microtubules are positioned and oriented are poorly understood. In higher plants, nucleation of microtubules arises from distributed γ-tubulin ring complexes (γ-TuRCs) at the cell cortex that are associated primarily with existing microtubules and from which new microtubules are nucleated in a geometrically bimodal fashion, either in parallel to the mother microtubule or as a branching event at a mean angle of approximately 40° to the mother microtubule. By imaging the dynamics of individual nucleation events in Arabidopsis, we found that a conserved peripheral protein of the γ-TuRC, GCP-WD/NEDD1, associated with motile γ-TuRCs and localized to nucleation events. Knockdown of this essential protein resulted in reduction of γ-TuRC recruitment to cortical microtubules and total nucleation frequency, showing that GCP-WD controls γ-TuRC positioning and function in these interphase arrays. Further, we discovered an unexpected role for GCP-WD in determining the geometry of microtubule-dependent microtubule nucleation, where it acts to increase the likelihood of branching over parallel nucleation. Cells with normally complex patterns of cortical array organization constructed simpler arrays with cell-wide ordering, suggesting that control of nucleation frequency, positioning, and geometry by GCP-WD allows plant cells to build alternative cortical array architectures.
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Affiliation(s)
- Ankit Walia
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Masayoshi Nakamura
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Dorianne Moss
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Viktor Kirik
- School of Biological Sciences, Illinois State University, Normal, IL 61710, USA
| | - Takashi Hashimoto
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630-0192, Japan
| | - David W Ehrhardt
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA; Department of Biology, Stanford University, Stanford, CA 94305, USA.
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21
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Baumann H, Surrey T. Motor-mediated cortical versus astral microtubule organization in lipid-monolayered droplets. J Biol Chem 2014; 289:22524-35. [PMID: 24966327 PMCID: PMC4139258 DOI: 10.1074/jbc.m114.582015] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Revised: 06/20/2014] [Indexed: 01/19/2023] Open
Abstract
The correct spatial organization of microtubules is of crucial importance for determining the internal architecture of eukaryotic cells. Microtubules are arranged in space by a multitude of biochemical activities and by spatial constraints imposed by the cell boundary. The principles underlying the establishment of distinct intracellular architectures are only poorly understood. Here, we studied the effect of spatial confinement on the self-organization of purified motors and microtubules that are encapsulated in lipid-monolayered droplets in oil, varying in diameter from 5-100 μm, which covers the size range of typical cell bodies. We found that droplet size alone had a major organizing influence. The presence of a microtubule-crosslinking motor protein decreased the number of accessible types of microtubule organizations. Depending on the degree of spatial confinement, the presence of the motor caused either the formation of a cortical array of bent microtubule bundles or the generation of single microtubule asters in the droplets. These are two of the most prominent forms of microtubule arrangements in plant and metazoan cells. Our results provide insights into the combined organizing influence of spatial constraints and cross-linking motor activities determining distinct microtubule architectures in a minimal biomimetic system. In the future, this simple lipid-monolayered droplet system characterized here can be expanded readily to include further biochemical activities or used as the starting point for the investigation of motor-mediated microtubule organization inside liposomes surrounded by a deformable lipid bilayer.
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Affiliation(s)
- Hella Baumann
- From the London Research Institute, Cancer Research UK, 44 Lincoln's Inn Fields, London WC2A 3LY, United Kingdom
| | - Thomas Surrey
- From the London Research Institute, Cancer Research UK, 44 Lincoln's Inn Fields, London WC2A 3LY, United Kingdom
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22
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Microtubule networks for plant cell division. SYSTEMS AND SYNTHETIC BIOLOGY 2014; 8:187-94. [PMID: 25136380 DOI: 10.1007/s11693-014-9142-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Revised: 03/21/2014] [Accepted: 03/24/2014] [Indexed: 10/25/2022]
Abstract
During cytokinesis the cytoplasm of a cell is divided to form two daughter cells. In animal cells, the existing plasma membrane is first constricted and then abscised to generate two individual plasma membranes. Plant cells on the other hand divide by forming an interior dividing wall, the so-called cell plate, which is constructed by localized deposition of membrane and cell wall material. Construction starts in the centre of the cell at the locus of the mitotic spindle and continues radially towards the existing plasma membrane. Finally the membrane of the cell plate and plasma membrane fuse to form two individual plasma membranes. Two microtubule-based cytoskeletal networks, the phragmoplast and the pre-prophase band (PPB), jointly control cytokinesis in plants. The bipolar microtubule array of the phragmoplast regulates cell plate deposition towards a cortical position that is templated by the ring-shaped microtubule array of the PPB. In contrast to most animal cells, plants do not use centrosomes as foci of microtubule growth initiation. Instead, plant microtubule networks are striking examples of self-organizing systems that emerge from physically constrained interactions of dispersed microtubules. Here we will discuss how microtubule-based activities including growth, shrinkage, severing, sliding, nucleation and bundling interrelate to jointly generate the required ordered structures. Evidence mounts that adapter proteins sense the local geometry of microtubules to locally modulate the activity of proteins involved in microtubule growth regulation and severing. Many of the proteins and mechanisms involved have roles in other microtubule assemblies as well, bestowing broader relevance to insights gained from plants.
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