1
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Saltini M, Deinum EE. Microtubule simulations in plant biology: A field coming to maturity. CURRENT OPINION IN PLANT BIOLOGY 2024; 81:102596. [PMID: 38981324 DOI: 10.1016/j.pbi.2024.102596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 05/24/2024] [Accepted: 06/10/2024] [Indexed: 07/11/2024]
Abstract
The plant cortical microtubule array is an important determinant of cell wall structure and, therefore, plant morphology and physiology. The array consists of dynamic microtubules interacting through frequent collisions. Since the discovery by Dixit and Cyr (2004) that the outcome of such collisions depends on the collision angle, computer simulations have been indispensable in studying array behaviour. Over the last decade, the available simulation tools have drastically improved: multiple high-quality simulation platforms exist with specific strengths and applications. Here, we review how these platforms differ on the critical aspects of microtubule nucleation, flexibility, and local orienting cues; and how such differences affect array behaviour. Building upon concepts and control parameters from theoretical models of collective microtubule behaviour, we conclude that all these factors matter in the debate about what is most important for orienting the array: local cues like mechanical stresses or global cues deriving from the cell geometry.
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Affiliation(s)
- Marco Saltini
- Mathematical & Statistical Methods (Biometris), Plant Science Group, Wageningen University, 6708 PB Wageningen, the Netherlands
| | - Eva E Deinum
- Mathematical & Statistical Methods (Biometris), Plant Science Group, Wageningen University, 6708 PB Wageningen, the Netherlands.
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2
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Feiguelman G, Cui X, Sternberg H, Hur EB, Higa T, Oda Y, Fu Y, Yalovsky S. Microtubule-associated ROP interactors affect microtubule dynamics and modulate cell wall patterning and root hair growth. Development 2022; 149:279331. [PMID: 36314989 PMCID: PMC9845754 DOI: 10.1242/dev.200811] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Accepted: 10/24/2022] [Indexed: 11/22/2022]
Abstract
Rho of plant (ROP) proteins and the interactor of constitutively active ROP (ICR) family member ICR5/MIDD1 have been implicated to function as signaling modules that regulate metaxylem secondary cell wall patterning. Yet, loss-of-function mutants of ICR5 and its closest homologs have not been studied and, hence, the functions of these ICR family members are not fully established. Here, we studied the functions of ICR2 and its homolog ICR5. We show that ICR2 is a microtubule-associated protein that affects microtubule dynamics. Secondary cell wall pits in the metaxylem of Arabidopsis icr2 and icr5 single mutants and icr2 icr5 double mutants are smaller than those in wild-type Col-0 seedlings; however, they are remarkably denser, implying a complex function of ICRs in secondary cell wall patterning. ICR5 has a unique function in protoxylem secondary cell wall patterning, whereas icr2, but not icr5, mutants develop split root hairs, demonstrating functional diversification. Taken together, our results show that ICR2 and ICR5 have unique and cooperative functions as microtubule-associated proteins and as ROP effectors.
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Affiliation(s)
- Gil Feiguelman
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Xiankui Cui
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Hasana Sternberg
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Eliran Ben Hur
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Takeshi Higa
- Department of Gene Phenomics and Function, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan
| | - Yoshihisa Oda
- Department of Gene Phenomics and Function, National Institute of Genetics, Mishima, Shizuoka 411-8540, Japan,Department of Genetics, School of Life Science, The Graduate University for Advanced Studies, SOKENDAI, Mishima, Shizuoka 411-8540, Japan
| | - Ying Fu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China,Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education, Beijing 100193, China
| | - Shaul Yalovsky
- School of Plant Sciences and Food Security, Tel Aviv University, Tel Aviv 6997801, Israel,Author for correspondence (; )
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3
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Saltini M, Mulder BM. A plausible mechanism for longitudinal lock-in of the plant cortical microtubule array after light-induced reorientation. QUANTITATIVE PLANT BIOLOGY 2021; 2:e9. [PMID: 37077209 PMCID: PMC10095967 DOI: 10.1017/qpb.2021.9] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 03/30/2021] [Accepted: 04/21/2021] [Indexed: 05/03/2023]
Abstract
The light-induced reorientation of the cortical microtubule array in dark-grown Arabidopsis thaliana hypocotyl cells is a striking example of the dynamical plasticity of the microtubule cytoskeleton. A consensus model, based on katanin-mediated severing at microtubule crossovers, has been developed that successfully describes the onset of the observed switch between a transverse and longitudinal array orientation. However, we currently lack an understanding of why the newly populated longitudinal array direction remains stable for longer times and re-equilibration effects would tend to drive the system back to a mixed orientation state. Using both simulations and analytical calculations, we show that the assumption of a small orientation-dependent shift in microtubule dynamics is sufficient to explain the long-term lock-in of the longitudinal array orientation. Furthermore, we show that the natural alternative hypothesis that there is a selective advantage in severing longitudinal microtubules, is neither necessary nor sufficient to achieve cortical array reorientation, but is able to accelerate this process significantly.
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Affiliation(s)
- Marco Saltini
- Department of Ecology and Genetics, Animal Ecology, Uppsala University, Uppsala, Sweden
- Author for correspondence: M. Saltini, E-mail:
| | - Bela M. Mulder
- Living Matter Department, AMOLF, Amsterdam, The Netherlands
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4
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Molines AT, Marion J, Chabout S, Besse L, Dompierre JP, Mouille G, Coquelle FM. EB1 contributes to microtubule bundling and organization, along with root growth, in Arabidopsis thaliana. Biol Open 2018; 7:bio.030510. [PMID: 29945874 PMCID: PMC6124560 DOI: 10.1242/bio.030510] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Microtubules are involved in plant development and adaptation to their environment, but the sustaining molecular mechanisms remain elusive. Microtubule-end-binding 1 (EB1) proteins participate in directional root growth in Arabidopsis thaliana. However, a connection to the underlying microtubule array has not been established yet. We show here that EB1 proteins contribute to the organization of cortical microtubules in growing epidermal plant cells, without significant modulation of microtubule dynamics. Using super-resolution stimulated emission depletion (STED) microscopy and an original quantification approach, we also demonstrate a significant reduction of apparent microtubule bundling in cytoplasmic-EB1-deficient plants, suggesting a function for EB1 in the interaction between adjacent microtubules. Furthermore, we observed root growth defects in EB1-deficient plants, which are not related to cell division impairment. Altogether, our results support a role for EB1 proteins in root development, in part by maintaining the organization of cortical microtubules. This article has an associated First Person interview with the first author of the paper. Summary: EB1 proteins affect cortical-microtubule bundling and organization in Arabidopsis thaliana, without significant modulation of microtubule dynamics. They also participate in root growth, further linking microtubules to plant development.
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Affiliation(s)
- Arthur T Molines
- Department of Cell Biology, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France
| | - Jessica Marion
- Department of Cell Biology, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France
| | - Salem Chabout
- Institut Jean-Pierre Bourgin (IJPB), INRA - AgroParisTech, 78026 Versailles Cedex, France
| | - Laetitia Besse
- Light Microscopy Facility, Imagerie-Gif, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France
| | - Jim P Dompierre
- Light Microscopy Facility, Imagerie-Gif, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France
| | - Grégory Mouille
- Institut Jean-Pierre Bourgin (IJPB), INRA - AgroParisTech, 78026 Versailles Cedex, France
| | - Frédéric M Coquelle
- Department of Cell Biology, Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette Cedex, France
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5
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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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6
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Wang C, Liu W, Wang G, Li J, Dong L, Han L, Wang Q, Tian J, Yu Y, Gao C, Kong Z. KTN80 confers precision to microtubule severing by specific targeting of katanin complexes in plant cells. EMBO J 2017; 36:3435-3447. [PMID: 28978669 DOI: 10.15252/embj.201796823] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Revised: 08/31/2017] [Accepted: 09/08/2017] [Indexed: 11/09/2022] Open
Abstract
The microtubule (MT)-severing enzyme katanin triggers dynamic reorientation of cortical MT arrays that play crucial functions during plant cell morphogenesis, such as cell elongation, cell wall biosynthesis, and hormonal signaling. MT severing specifically occurs at crossover or branching nucleation sites in living Arabidopsis cells. This differs from the random severing observed along the entire length of single MTs in vitro and strongly suggests that a precise control mechanism must exist in vivo However, how katanin senses and cleaves at MT crossover and branching nucleation sites in vivo has remained unknown. Here, we show that the katanin p80 subunit KTN80 confers precision to MT severing by specific targeting of the katanin p60 subunit KTN1 to MT cleavage sites and that KTN1 is required for oligomerization of functional KTN80-KTN1 complexes that catalyze severing. Moreover, our findings suggest that the katanin complex in Arabidopsis is composed of a hexamer of KTN1-KTN80 heterodimers that sense MT geometry to confer precise MT severing. Our findings shed light on the precise control mechanism of MT severing in plant cells, which may be relevant for other eukaryotes.
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Affiliation(s)
- Chaofeng Wang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Weiwei Liu
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Guangda Wang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Jun Li
- University of Chinese Academy of Sciences, Beijing, China.,State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Li Dong
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Libo Han
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Qi Wang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Juan Tian
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Yanjun Yu
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Caixia Gao
- State Key Laboratory of Plant Cell and Chromosome Engineering, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, China
| | - Zhaosheng Kong
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
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7
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Zhang Q, Song P, Qu Y, Wang P, Jia Q, Guo L, Zhang C, Mao T, Yuan M, Wang X, Zhang W. Phospholipase Dδ negatively regulates plant thermotolerance by destabilizing cortical microtubules in Arabidopsis. PLANT, CELL & ENVIRONMENT 2017; 40:2220-2235. [PMID: 28710795 DOI: 10.1111/pce.13023] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/30/2017] [Accepted: 07/02/2017] [Indexed: 05/20/2023]
Abstract
The pattern of cortical microtubule arrays plays an important role in plant growth and adaptation in response to hormonal and environmental changes. Cortical microtubules are connected with the plasma membrane (PM); however, how the membrane affects cortical microtubule organization is not well understood. Here, we showed that phospholipase Dδ (PLDδ) was associated with the PM and co-localized with microtubules in cells. In vitro analysis revealed that PLDδ bound to microtubules, resulting in microtubule disorganization. Site-specific mutations that decreased PLDδ enzymatic activity impaired its effects on destabilizing microtubule organization. Heat shock transiently activated PLDδ, without any change of its PM localization, triggering microtubule dissociation from PM and depolymerization and seedling death in Arabidopsis, but these effects were alleviated in pldδ knockout mutants. Complementation of pldδ with wild-type PLDδ, but not mutated PLDδ, restored the phenotypes of microtubules and seedling survival to those of wild-type Arabidopsis. Thus, we conclude that the PM-associated PLDδ negatively regulates plant thermotolerance via destabilizing cortical microtubules, in an activity-dependent manner, rather than its subcellular translocation.
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Affiliation(s)
- Qun Zhang
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Ping Song
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Yana Qu
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Peipei Wang
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Qianru Jia
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Liang Guo
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China
| | - Chuanpeng Zhang
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
| | - Tonglin Mao
- College of Biology, China Agricultural University, Beijing, 100083, China
| | - Ming Yuan
- College of Biology, China Agricultural University, Beijing, 100083, China
| | - Xuemin Wang
- Department of Biology, University of Missouri, St Louis, MO, 63121, USA
- Donald Danforth Plant Science Center, St Louis, MO, 63132, USA
| | - Wenhua Zhang
- College of Life Sciences, State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China
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8
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Torisawa T, Taniguchi D, Ishihara S, Oiwa K. Spontaneous Formation of a Globally Connected Contractile Network in a Microtubule-Motor System. Biophys J 2017; 111:373-385. [PMID: 27463139 PMCID: PMC4968425 DOI: 10.1016/j.bpj.2016.06.010] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 04/19/2016] [Accepted: 06/08/2016] [Indexed: 11/01/2022] Open
Abstract
Microtubule (MT) networks play key roles in cell division, intracellular transport, and cell motility. These functions of MT networks occur through interactions between MTs and various associated proteins, notably motor proteins that bundle and slide MTs. Our objective in this study was to address the question of how motors determine the nature of MT networks. We conducted in vitro assays using homotetrameric kinesin Eg5, a motor protein involved in the formation and maintenance of the mitotic spindle. The mixing of Eg5 and MTs produced a range of spatiotemporal dynamics depending on the motor/filament ratio. Low motor/filament ratios produced globally connected static MT networks with sparsely distributed contractile active nodes (motor-accumulating points with radially extending MTs). Increasing the motor/filament ratio facilitated the linking of contractile active nodes and led to a global contraction of the network. When the motor/filament ratio was further increased, densely distributed active nodes formed local clusters and segmented the network into pieces with their strong contractile forces. Altering the properties of the motor through the use of chimeric Eg5, which has kinesin-1 heads, resulted in the generation of many isolated asters. These results suggest that the spatial distribution of contractile active nodes determines the dynamics of MT-motor networks. We then developed a coarse-grained model of MT-motor networks and identified two essential features for reproducing the experimentally observed patterns: an accumulation of motors that form the active nodes necessary to generate contractile forces, and a nonlinear dependency of contractile force on motor densities. Our model also enabled us to characterize the mechanical properties of the contractile network. Our study provides insight into how local motor-MT interactions generate the spatiotemporal dynamics of macroscopic network structures.
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Affiliation(s)
- Takayuki Torisawa
- National Institute of Information and Communications Technology, Advanced ICT Research Institute, Kobe, Hyogo, Japan
| | | | - Shuji Ishihara
- Department of Physics, Meiji University, Kawasaki, Kanagawa, Japan
| | - Kazuhiro Oiwa
- National Institute of Information and Communications Technology, Advanced ICT Research Institute, Kobe, Hyogo, Japan.
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9
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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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10
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Steiner A, Müller L, Rybak K, Vodermaier V, Facher E, Thellmann M, Ravikumar R, Wanner G, Hauser MT, Assaad FF. The Membrane-Associated Sec1/Munc18 KEULE is Required for Phragmoplast Microtubule Reorganization During Cytokinesis in Arabidopsis. MOLECULAR PLANT 2016; 9:528-540. [PMID: 26700031 DOI: 10.1016/j.molp.2015.12.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 10/28/2015] [Accepted: 12/03/2015] [Indexed: 06/05/2023]
Abstract
Cytokinesis, the partitioning of the cytoplasm following nuclear division, requires extensive coordination between membrane trafficking and cytoskeletal dynamics. In plants, the onset of cytokinesis is characterized by the assembly of a bipolar microtubule array, the phragmoplast, and of a transient membrane compartment, the cell plate. Little is known about the coordination between membrane deposition at the cell plate and the dynamics of phragmoplast microtubules. In this study, we monitor the localization dynamics of microtubule and membrane markers throughout cytokinesis. Our spatiotemporal resolution is consistent with the general view that microtubule dynamics drive membrane movements. Nonetheless, we provide evidence for active sorting at the cell plate and show that this is, at least in part, mediated by the TRAPPII tethering complex. We also characterize phragmoplast microtubule organization and cell plate formation in a suite of cytokinesis-defective mutants. Of four mutant lines with defects in phragmoplast microtubule organization, only mor1 microtubule-associated mutants exhibited aberrant cell plates. Conversely, the mutants with the strongest impairment in phragmoplast microtubule reorganization are keule alleles, which have a primary defect in membrane fusion. Our findings identify the SEC1/Munc18 protein KEULE as a central regulatory node in the coordination of membrane and microtubule dynamics during plant cytokinesis.
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Affiliation(s)
- Alexander Steiner
- Botany Department, School of Life Sciences, Technische Universität München, Emil-Ramann-Street 4, 85354 Freising, Germany
| | - Lin Müller
- Botany Department, School of Life Sciences, Technische Universität München, Emil-Ramann-Street 4, 85354 Freising, Germany
| | - Katarzyna Rybak
- Botany Department, School of Life Sciences, Technische Universität München, Emil-Ramann-Street 4, 85354 Freising, Germany
| | - Vera Vodermaier
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | - Eva Facher
- Department Biologie I, Ludwig-Maximillians Universität, 82152 Planegg-Martinsried, Germany
| | - Martha Thellmann
- Botany Department, School of Life Sciences, Technische Universität München, Emil-Ramann-Street 4, 85354 Freising, Germany
| | - Raksha Ravikumar
- Botany Department, School of Life Sciences, Technische Universität München, Emil-Ramann-Street 4, 85354 Freising, Germany
| | - Gerhard Wanner
- Department Biologie I, Ludwig-Maximillians Universität, 82152 Planegg-Martinsried, Germany
| | - Marie-Theres Hauser
- Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, 1190 Vienna, Austria
| | - Farhah F Assaad
- Botany Department, School of Life Sciences, Technische Universität München, Emil-Ramann-Street 4, 85354 Freising, Germany.
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11
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Abstract
Microtubules mediate important cellular processes by forming highly ordered arrays. Organization of these networks is achieved by nucleating and anchoring microtubules at centrosomes and other structures collectively known as microtubule-organizing centers (MTOCs). However, the diverse microtubule configurations found in different cell types may not be generated and maintained by MTOCs alone. Work over the last few years has revealed a mechanism that has the capacity to generate cell-type-specific microtubule arrays independently of a specific organizer: nucleation of microtubules from the lateral surface of pre-existing microtubules. This type of nucleation requires cooperation between two different multi-subunit protein complexes, augmin and the γ-tubulin ring complex (γTuRC). Here we review recent molecular insight into microtubule-dependent nucleation and discuss the possibility that the augmin-γTuRC module, initially described in mitosis, may broadly contribute to microtubule organization also in non-mitotic cells.
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Affiliation(s)
- Carlos Sánchez-Huertas
- Institute for Research in Biomedicine (IRB Barcelona), C/ Baldiri Reixac 10, Barcelona, Spain
| | - Jens Lüders
- Institute for Research in Biomedicine (IRB Barcelona), C/ Baldiri Reixac 10, Barcelona, Spain.
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12
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Khuc Trong P, Doerflinger H, Dunkel J, St Johnston D, Goldstein RE. Cortical microtubule nucleation can organise the cytoskeleton of Drosophila oocytes to define the anteroposterior axis. eLife 2015; 4. [PMID: 26406117 PMCID: PMC4580948 DOI: 10.7554/elife.06088] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 08/14/2015] [Indexed: 02/02/2023] Open
Abstract
Many cells contain non-centrosomal arrays of microtubules (MTs), but the assembly, organisation and function of these arrays are poorly understood. We present the first theoretical model for the non-centrosomal MT cytoskeleton in Drosophila oocytes, in which bicoid and oskar mRNAs become localised to establish the anterior-posterior body axis. Constrained by experimental measurements, the model shows that a simple gradient of cortical MT nucleation is sufficient to reproduce the observed MT distribution, cytoplasmic flow patterns and localisation of oskar and naive bicoid mRNAs. Our simulations exclude a major role for cytoplasmic flows in localisation and reveal an organisation of the MT cytoskeleton that is more ordered than previously thought. Furthermore, modulating cortical MT nucleation induces a bifurcation in cytoskeletal organisation that accounts for the phenotypes of polarity mutants. Thus, our three-dimensional model explains many features of the MT network and highlights the importance of differential cortical MT nucleation for axis formation. DOI:http://dx.doi.org/10.7554/eLife.06088.001 Cells contain a network of filaments known as microtubules that serve as tracks along which proteins and other materials can be moved from one location to another. For example, molecules called messenger ribonucleic acids (or mRNAs for short) are made in the nucleus and are then moved to various locations around the cell. Each mRNA molecule encodes the instructions needed to make a particular protein and the network of microtubules allows these molecules to be directed to wherever these proteins are needed. In female fruit flies, an mRNA called bicoid is moved to one end (called the anterior end) of a developing egg cell, while another mRNA called oskar is moved to the opposite (posterior) end. These mRNAs determine which ends of the cell will give rise to the head and the abdomen if the egg is fertilized. The microtubules start to form at sites near the inner face of the membrane that surrounds the cell, known as the cortex. From there, the microtubules grow towards the interior of the egg cell. However, it is not clear how this allows bicoid, oskar and other mRNAs to be moved to the correct locations. Khuc Trong et al. used a combination of computational and experimental techniques to develop a model of how microtubules form in the egg cells of fruit flies. The model produces a very similar arrangement of microtubules as observed in living cells and can reproduce the patterns of bicoid and oskar RNA movements. This study suggests that microtubules are more highly organised than previously thought. Furthermore, Khuc Trong et al.'s findings indicate that the anchoring of microtubules in the cortex is sufficient to direct bicoid and oskar RNAs to the opposite ends of the cell. The next challenge will be to find out how the microtubules are linked to the cortex and how this is regulated. DOI:http://dx.doi.org/10.7554/eLife.06088.002
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Affiliation(s)
- Philipp Khuc Trong
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom
| | - Hélène Doerflinger
- Wellcome Trust/Cancer Research UK Gurdon Institute, Henry Wellcome Building of Cancer and Developmental Biology, University of Cambridge, Cambridge, United Kingdom
| | - Jörn Dunkel
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom
| | - Daniel St Johnston
- Wellcome Trust/Cancer Research UK Gurdon Institute, Henry Wellcome Building of Cancer and Developmental Biology, University of Cambridge, Cambridge, United Kingdom
| | - Raymond E Goldstein
- Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge, United Kingdom
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Nakamura M. Microtubule nucleating and severing enzymes for modifying microtubule array organization and cell morphogenesis in response to environmental cues. THE NEW PHYTOLOGIST 2015; 205:1022-7. [PMID: 25729799 DOI: 10.1111/nph.12932] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
In higher plants, reorientation of cortical microtubule arrays has been postulated to be of importance for modifying cell growth to adapt to environmental conditions. However, the process of microtubule reorientation is largely unknown. Recent genetic and live cell imaging studies of microtubule dynamics shed light on the regulatory mechanisms of microtubule molecular nucleation and severing apparatuses, which are required for array reorientation in response to blue light signaling. Branching nucleation from γ-tubulin complexes creates a small population of discordant microtubules that are acted on by KATANIN-mediated severing in two ways. KATANIN releases microtubules from nucleation sites and rapidly amplifies discordant microtubules by severing at microtubule crossovers. In this review, I focus on the molecular details of these two enzymes, which enable microtubule array transition.
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14
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Breuer D, Ivakov A, Sampathkumar A, Hollandt F, Persson S, Nikoloski Z. Quantitative analyses of the plant cytoskeleton reveal underlying organizational principles. J R Soc Interface 2015; 11:20140362. [PMID: 24920110 DOI: 10.1098/rsif.2014.0362] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The actin and microtubule (MT) cytoskeletons are vital structures for cell growth and development across all species. While individual molecular mechanisms underpinning actin and MT dynamics have been intensively studied, principles that govern the cytoskeleton organization remain largely unexplored. Here, we captured biologically relevant characteristics of the plant cytoskeleton through a network-driven imaging-based approach allowing us to quantitatively assess dynamic features of the cytoskeleton. By introducing suitable null models, we demonstrate that the plant cytoskeletal networks exhibit properties required for efficient transport, namely, short average path lengths and high robustness. We further show that these advantageous features are maintained during temporal cytoskeletal rearrangements. Interestingly, man-made transportation networks exhibit similar properties, suggesting general laws of network organization supporting diverse transport processes. The proposed network-driven analysis can be readily used to identify organizational principles of cytoskeletons in other organisms.
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Affiliation(s)
- David Breuer
- Systems Biology and Mathematical Modeling, Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, Potsdam 14476, Germany
| | - Alexander Ivakov
- Plant Cell Walls, Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, Potsdam 14476, Germany
| | - Arun Sampathkumar
- Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge CB2 1LR, UK
| | - Florian Hollandt
- Systems Biology and Mathematical Modeling, Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, Potsdam 14476, Germany
| | - Staffan Persson
- Plant Cell Walls, Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, Potsdam 14476, Germany ARC Centre of Excellence in Plant Cell Walls, School of Botany, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Zoran Nikoloski
- Systems Biology and Mathematical Modeling, Max Planck Institute of Molecular Plant Physiology, Am Muehlenberg 1, Potsdam 14476, Germany
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15
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Augmin Triggers Microtubule-Dependent Microtubule Nucleation in Interphase Plant Cells. Curr Biol 2014; 24:2708-13. [DOI: 10.1016/j.cub.2014.09.053] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 09/04/2014] [Accepted: 09/22/2014] [Indexed: 11/19/2022]
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16
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Komis G, Mistrik M, Šamajová O, Doskočilová A, Ovečka M, Illés P, Bartek J, Šamaj J. Dynamics and organization of cortical microtubules as revealed by superresolution structured illumination microscopy. PLANT PHYSIOLOGY 2014; 165:129-48. [PMID: 24686112 PMCID: PMC4012574 DOI: 10.1104/pp.114.238477] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 03/28/2014] [Indexed: 05/07/2023]
Abstract
Plants employ acentrosomal mechanisms to organize cortical microtubule arrays essential for cell growth and differentiation. Using structured illumination microscopy (SIM) adopted for the optimal documentation of Arabidopsis (Arabidopsis thaliana) hypocotyl epidermal cells, dynamic cortical microtubules labeled with green fluorescent protein fused to the microtubule-binding domain of the mammalian microtubule-associated protein MAP4 and with green fluorescent protein-fused to the alpha tubulin6 were comparatively recorded in wild-type Arabidopsis plants and in the mitogen-activated protein kinase mutant mpk4 possessing the former microtubule marker. The mpk4 mutant exhibits extensive microtubule bundling, due to increased abundance and reduced phosphorylation of the microtubule-associated protein MAP65-1, thus providing a very useful genetic tool to record intrabundle microtubule dynamics at the subdiffraction level. SIM imaging revealed nano-sized defects in microtubule bundling, spatially resolved microtubule branching and release, and finally allowed the quantification of individual microtubules within cortical bundles. Time-lapse SIM imaging allowed the visualization of subdiffraction, short-lived excursions of the microtubule plus end, and dynamic instability behavior of both ends during free, intrabundle, or microtubule-templated microtubule growth and shrinkage. Finally, short, rigid, and nondynamic microtubule bundles in the mpk4 mutant were observed to glide along the parent microtubule in a tip-wise manner. In conclusion, this study demonstrates the potential of SIM for superresolution time-lapse imaging of plant cells, showing unprecedented details accompanying microtubule dynamic organization.
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Affiliation(s)
- George Komis
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University Olomouc, 783 71 Olomouc, Czech Republic (G.K., O.Š., A.D., M.O., P.I., J.Š.)
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, 779 00 Olomouc, Czech Republic (M.M., J.B.); and
- Danish Cancer Society Research Center, DK–2100 Copenhagen, Denmark (J.B.)
| | - Martin Mistrik
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University Olomouc, 783 71 Olomouc, Czech Republic (G.K., O.Š., A.D., M.O., P.I., J.Š.)
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, 779 00 Olomouc, Czech Republic (M.M., J.B.); and
- Danish Cancer Society Research Center, DK–2100 Copenhagen, Denmark (J.B.)
| | - Olga Šamajová
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University Olomouc, 783 71 Olomouc, Czech Republic (G.K., O.Š., A.D., M.O., P.I., J.Š.)
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, 779 00 Olomouc, Czech Republic (M.M., J.B.); and
- Danish Cancer Society Research Center, DK–2100 Copenhagen, Denmark (J.B.)
| | - Anna Doskočilová
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University Olomouc, 783 71 Olomouc, Czech Republic (G.K., O.Š., A.D., M.O., P.I., J.Š.)
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, 779 00 Olomouc, Czech Republic (M.M., J.B.); and
- Danish Cancer Society Research Center, DK–2100 Copenhagen, Denmark (J.B.)
| | - Miroslav Ovečka
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University Olomouc, 783 71 Olomouc, Czech Republic (G.K., O.Š., A.D., M.O., P.I., J.Š.)
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, 779 00 Olomouc, Czech Republic (M.M., J.B.); and
- Danish Cancer Society Research Center, DK–2100 Copenhagen, Denmark (J.B.)
| | - Peter Illés
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University Olomouc, 783 71 Olomouc, Czech Republic (G.K., O.Š., A.D., M.O., P.I., J.Š.)
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, 779 00 Olomouc, Czech Republic (M.M., J.B.); and
- Danish Cancer Society Research Center, DK–2100 Copenhagen, Denmark (J.B.)
| | - Jiri Bartek
- Centre of the Region Haná for Biotechnological and Agricultural Research, Department of Cell Biology, Faculty of Science, Palacký University Olomouc, 783 71 Olomouc, Czech Republic (G.K., O.Š., A.D., M.O., P.I., J.Š.)
- Institute of Molecular and Translational Medicine, Faculty of Medicine and Dentistry, Palacký University Olomouc, 779 00 Olomouc, Czech Republic (M.M., J.B.); and
- Danish Cancer Society Research Center, DK–2100 Copenhagen, Denmark (J.B.)
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Abstract
Historically, cell biologists studied organisms that represented a reasonable sampling of life's diversity, whereas recently research has narrowed into a few model systems. As a result, the cells of plants have been relatively neglected. Here I choose three examples to illustrate how plants have been informative and could be even more so. Owing to their ease of imaging and genetic tractability, multicellular plant model systems provide a unique opportunity to address long-standing questions in cell biology.
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Affiliation(s)
- Magdalena Bezanilla
- Department of Biology, University of Massachusetts Amherst, Amherst, MA 01003, USA.
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18
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Hashimoto T. A ring for all: γ-tubulin-containing nucleation complexes in acentrosomal plant microtubule arrays. CURRENT OPINION IN PLANT BIOLOGY 2013; 16:698-703. [PMID: 24075308 DOI: 10.1016/j.pbi.2013.09.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 08/24/2013] [Accepted: 09/04/2013] [Indexed: 06/02/2023]
Abstract
The construction of dynamic polar microtubules from 13 protofilaments consisting of α-tubulin and β-tubulin heterodimers requires a preformed nucleation seed that specifies subcellular localization and timing of microtubule polymerization in vivo. An evolutionarily conserved γ-tubulin-containing ring complex is recruited to the lateral wall of preexisting microtubules or outer nuclear membranes in plant cells, and is then activated as a template for new microtubules of defined geometry. Specific regulators are thought to target/activate the ring complex to nucleate nascent microtubules in distinct polymerization patterns, as seen in interphase and mitotic arrays. The augmin complex, which was initially identified in metazoan cells, recruits the ring complex to plant mitotic microtubules, where new polymers are abundantly generated at shallow angles.
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Affiliation(s)
- Takashi Hashimoto
- Nara Institute of Science and Technology, Graduate School of Biological Sciences, Japan.
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19
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Haikonen T, Rajamäki ML, Valkonen JPT. Interaction of the microtubule-associated host protein HIP2 with viral helper component proteinase is important in infection with potato virus A. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2013; 26:734-44. [PMID: 23489059 DOI: 10.1094/mpmi-01-13-0023-r] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Microtubules (MT) outline and maintain the overall shape of cells and can reorganize cellular membranes to serve as sites of RNA virus replication. Here, we provide data on involvement of an MT-associated protein in infection of plants with a potyvirus, Potato virus A (PVA), representing the largest family of plant-infecting RNA viruses. Our results showed that helper-component proteinase (HCpro)-interacting protein 2 (HIP2) of potato (Solanum tuberosum) is an MT-associated protein similar to Arabidopsis SPR2. Virus-induced silencing of HIP2 in Nicotiana benthamiana resulted in a spiral-like growth phenotype, similar to the Arabidopsis spr2 mutant, and the spr2 phenotype in Arabidopsis was complemented with potato HIP2. HCpro of PVA interacted with HIP2 of potato and tobacco (Nicotiana tabacum). The interaction was detected by bimolecular fluorescence complementation in PVA-infected leaves on MT and MT intersections at the cell cortex. HIP2-HCpro interaction was determined by the C-proximal α-helix-rich domain of HIP2, whereas the N-proximal putative TOG domain and the central coiled-coil domain of HIP2 controlled HIP2 dimerization and binding to MT. Accumulation of PVA was significantly reduced in the HIP2-silenced leaves of N. benthamiana, which indicates that HIP2-HCpro interactions are important for virus infection.
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Affiliation(s)
- Tuuli Haikonen
- Department of Agricultural Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland
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20
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Cao L, Wang L, Zheng M, Cao H, Ding L, Zhang X, Fu Y. Arabidopsis AUGMIN subunit8 is a microtubule plus-end binding protein that promotes microtubule reorientation in hypocotyls. THE PLANT CELL 2013; 25:2187-201. [PMID: 23735294 PMCID: PMC3723620 DOI: 10.1105/tpc.113.113472] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
In plant cells, cortical microtubules provide tracks for cellulose-synthesizing enzymes and regulate cell division, growth, and morphogenesis. The role of microtubules in these essential cellular processes depends on the spatial arrangement of the microtubules. Cortical microtubules are reoriented in response to changes in cell growth status and cell shape. Therefore, an understanding of the mechanism that underlies the change in microtubule orientation will provide insight into plant cell growth and morphogenesis. This study demonstrated that AUGMIN subunit8 (AUG8) in Arabidopsis thaliana is a novel microtubule plus-end binding protein that participates in the reorientation of microtubules in hypocotyls when cell elongation slows down. AUG8 bound to the plus ends of microtubules and promoted tubulin polymerization in vitro. In vivo, AUG8 was recruited to the microtubule branch site immediately before nascent microtubules branched out. It specifically associated with the plus ends of growing cortical microtubules and regulated microtubule dynamics, which facilitated microtubule reorientation when microtubules changed their growth trajectory or encountered obstacle microtubules during microtubule reorientation. This study thus reveals a novel mechanism underlying microtubule reorientation that is critical for modulating cell elongation in Arabidopsis.
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Affiliation(s)
- Lingyan Cao
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Linhai Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Min Zheng
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Hong Cao
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Lian Ding
- Department of Vegetable Sciences, Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, China Agricultural University, Beijing 100193, China
| | - Xiaolan Zhang
- Department of Vegetable Sciences, Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, China Agricultural University, Beijing 100193, China
| | - Ying Fu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
- Address correspondence to
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21
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Bouxsein NF, Carroll-Portillo A, Bachand M, Sasaki DY, Bachand GD. A continuous network of lipid nanotubes fabricated from the gliding motility of kinesin powered microtubule filaments. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:2992-2999. [PMID: 23391254 DOI: 10.1021/la304238u] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Synthetic interconnected lipid nanotube networks were fabricated on the millimeter scale based on the simple, cooperative interaction between phospholipid vesicles and kinesin-microtubule (MT) transport systems. More specifically, taxol-stabilized MTs, in constant 2D motion via surface absorbed kinesin, extracted and extended lipid nanotube networks from large Lα phase multilamellar liposomes (5-25 μm). Based on the properties of the inverted motility geometry, the total size of these nanofluidic networks was limited by MT surface density, molecular motor energy source (ATP), and total amount and physical properties of lipid source material. Interactions between MTs and extended lipid nanotubes resulted in bifurcation of the nanotubes and ultimately the generation of highly branched networks of fluidically connected nanotubes. The network bifurcation was easily tuned by changing the density of microtubules on the surface to increase or decrease the frequency of branching. The ability of these networks to capture nanomaterials at the membrane surface with high fidelity was subsequently demonstrated using quantum dots as a model system. The diffusive transport of quantum dots was also characterized with respect to using these nanotube networks for mass transport applications.
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Affiliation(s)
- Nathan F Bouxsein
- Center for Integrated Nanotechnology, Sandia National Laboratories, Albuquerque, New Mexico 87123, USA
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22
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Vineyard L, Elliott A, Dhingra S, Lucas JR, Shaw SL. Progressive transverse microtubule array organization in hormone-induced Arabidopsis hypocotyl cells. THE PLANT CELL 2013; 25:662-76. [PMID: 23444330 PMCID: PMC3608785 DOI: 10.1105/tpc.112.107326] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2012] [Revised: 01/31/2013] [Accepted: 02/08/2013] [Indexed: 05/21/2023]
Abstract
The acentriolar cortical microtubule arrays in dark-grown hypocotyl cells organize into a transverse coaligned pattern that is critical for axial plant growth. In light-grown Arabidopsis thaliana seedlings, the cortical array on the outer (periclinal) cell face creates a variety of array patterns with a significant bias (>3:1) for microtubules polymerizing edge-ward and into the side (anticlinal) faces of the cell. To study the mechanisms required for creating the transverse coalignment, we developed a dual-hormone protocol that synchronously induces ∼80% of the light-grown hypocotyl cells to form transverse arrays over a 2-h period. Repatterning occurred in two phases, beginning with an initial 30 to 40% decrease in polymerizing plus ends prior to visible changes in the array pattern. Transverse organization initiated at the cell's midzone by 45 min after induction and progressed bidirectionally toward the apical and basal ends of the cell. Reorganization corrected the edge-ward bias in polymerization and proceeded without transiting through an obligate intermediate pattern. Quantitative comparisons of uninduced and induced microtubule arrays showed a limited deconstruction of the initial periclinal array followed by a progressive array reorganization to transverse coordinated between the anticlinal and periclinal cell faces.
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Affiliation(s)
- Laura Vineyard
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Andrew Elliott
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Sonia Dhingra
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Jessica R. Lucas
- Department of Biology, Santa Clara University, Santa Clara, California 95053
| | - Sidney L. Shaw
- Department of Biology, Indiana University, Bloomington, Indiana 47405
- Address correspondence to
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23
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Live-Cell Imaging of Microtubules and Microtubule-Associated Proteins in Arabidopsis thaliana. Methods Cell Biol 2013. [DOI: 10.1016/b978-0-12-407757-7.00015-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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24
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Juranić M, Srilunchang KO, Krohn NG, Leljak-Levanić D, Sprunck S, Dresselhaus T. Germline-specific MATH-BTB substrate adaptor MAB1 regulates spindle length and nuclei identity in maize. THE PLANT CELL 2012; 24:4974-91. [PMID: 23250449 PMCID: PMC3556970 DOI: 10.1105/tpc.112.107169] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2012] [Revised: 11/05/2012] [Accepted: 11/28/2012] [Indexed: 05/03/2023]
Abstract
Germline and early embryo development constitute ideal model systems to study the establishment of polarity, cell identity, and asymmetric cell divisions (ACDs) in plants. We describe here the function of the MATH-BTB domain protein MAB1 that is exclusively expressed in the germ lineages and the zygote of maize (Zea mays). mab1 (RNA interference [RNAi]) mutant plants display chromosome segregation defects and short spindles during meiosis that cause insufficient separation and migration of nuclei. After the meiosis-to-mitosis transition, two attached nuclei of similar identity are formed in mab1 (RNAi) mutants leading to an arrest of further germline development. Transient expression studies of MAB1 in tobacco (Nicotiana tabacum) Bright Yellow-2 cells revealed a cell cycle-dependent nuclear localization pattern but no direct colocalization with the spindle apparatus. MAB1 is able to form homodimers and interacts with the E3 ubiquitin ligase component Cullin 3a (CUL3a) in the cytoplasm, likely as a substrate-specific adapter protein. The microtubule-severing subunit p60 of katanin was identified as a candidate substrate for MAB1, suggesting that MAB1 resembles the animal key ACD regulator Maternal Effect Lethal 26 (MEL-26). In summary, our findings provide further evidence for the importance of posttranslational regulation for asymmetric divisions and germline progression in plants and identified an unstable key protein that seems to be involved in regulating the stability of a spindle apparatus regulator(s).
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Affiliation(s)
- Martina Juranić
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, 93053 Regensburg, Germany
- Department of Molecular Biology, Faculty of Science and Mathematics, University of Zagreb, 10000 Zagreb, Croatia
| | | | - Nádia Graciele Krohn
- Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirao Preto 14040-903, Brazil
| | - Dunja Leljak-Levanić
- Department of Molecular Biology, Faculty of Science and Mathematics, University of Zagreb, 10000 Zagreb, Croatia
| | - Stefanie Sprunck
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, 93053 Regensburg, Germany
| | - Thomas Dresselhaus
- Cell Biology and Plant Biochemistry, Biochemie-Zentrum Regensburg, University of Regensburg, 93053 Regensburg, Germany
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25
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Bringmann M, Landrein B, Schudoma C, Hamant O, Hauser MT, Persson S. Cracking the elusive alignment hypothesis: the microtubule-cellulose synthase nexus unraveled. TRENDS IN PLANT SCIENCE 2012; 17:666-74. [PMID: 22784824 PMCID: PMC3492759 DOI: 10.1016/j.tplants.2012.06.003] [Citation(s) in RCA: 77] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 06/06/2012] [Accepted: 06/08/2012] [Indexed: 05/02/2023]
Abstract
Directed plant cell growth is governed by deposition and alterations of cell wall components under turgor pressure. A key regulatory element of anisotropic growth, and hence cell shape, is the directional deposition of cellulose microfibrils. The microfibrils are synthesized by plasma membrane-located cellulose synthase complexes that co-align with and move along cortical microtubules. That the parallel relation between cortical microtubules and extracellular microfibrils is causal has been named the alignment hypothesis. Three recent studies revealed that the previously identified pom2 mutant codes for a large cellulose synthases interacting (CSI1) protein which also binds cortical microtubules. This review summarizes these findings, provides structure-function models and discusses the inferred mechanisms in the context of plant growth.
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Affiliation(s)
- Martin Bringmann
- Max-Planck-Institute for Molecular Plant Physiology, Am Muehlenberg 1, 14476 Potsdam, Germany
| | - Benoit Landrein
- Laboratoire de Reproduction et Développement des Plantes, INRA, CNRS, ENS, UCB Lyon 1, 46 Allée d’Italie, 69364 Lyon Cedex 07, France
- Laboratoire Joliot Curie, CNRS, ENS Lyon, UCB Lyon 1, Université de Lyon, 46 Allée, d’Italie, 69364 Lyon Cedex 07, France
| | - Christian Schudoma
- Max-Planck-Institute for Molecular Plant Physiology, Am Muehlenberg 1, 14476 Potsdam, Germany
| | - Olivier Hamant
- Laboratoire de Reproduction et Développement des Plantes, INRA, CNRS, ENS, UCB Lyon 1, 46 Allée d’Italie, 69364 Lyon Cedex 07, France
- Laboratoire Joliot Curie, CNRS, ENS Lyon, UCB Lyon 1, Université de Lyon, 46 Allée, d’Italie, 69364 Lyon Cedex 07, France
| | - Marie-Theres Hauser
- Institut of Applied Genetics and Cell Biology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria
| | - Staffan Persson
- Max-Planck-Institute for Molecular Plant Physiology, Am Muehlenberg 1, 14476 Potsdam, Germany
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Lee AHY, Hurley B, Felsensteiner C, Yea C, Ckurshumova W, Bartetzko V, Wang PW, Quach V, Lewis JD, Liu YC, Börnke F, Angers S, Wilde A, Guttman DS, Desveaux D. A bacterial acetyltransferase destroys plant microtubule networks and blocks secretion. PLoS Pathog 2012; 8:e1002523. [PMID: 22319451 PMCID: PMC3271077 DOI: 10.1371/journal.ppat.1002523] [Citation(s) in RCA: 127] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 12/21/2011] [Indexed: 02/06/2023] Open
Abstract
The eukaryotic cytoskeleton is essential for structural support and intracellular transport, and is therefore a common target of animal pathogens. However, no phytopathogenic effector has yet been demonstrated to specifically target the plant cytoskeleton. Here we show that the Pseudomonas syringae type III secreted effector HopZ1a interacts with tubulin and polymerized microtubules. We demonstrate that HopZ1a is an acetyltransferase activated by the eukaryotic co-factor phytic acid. Activated HopZ1a acetylates itself and tubulin. The conserved autoacetylation site of the YopJ / HopZ superfamily, K289, plays a critical role in both the avirulence and virulence function of HopZ1a. Furthermore, HopZ1a requires its acetyltransferase activity to cause a dramatic decrease in Arabidopsis thaliana microtubule networks, disrupt the plant secretory pathway and suppress cell wall-mediated defense. Together, this study supports the hypothesis that HopZ1a promotes virulence through cytoskeletal and secretory disruption. Many bacterial pathogens disrupt key components of host physiology by injecting virulence proteins (or “effectors”) via a needle-like structure, called the type III secretion system, directly into eukaryotic cells. The YopJ / HopZ superfamily of type III secreted effector proteins is found in pathogens of both animals and plants providing an excellent opportunity to address how a family of type III secreted effectors can promote pathogenesis in hosts from two kingdoms. YopJ from the animal pathogen Yersinia pestis is an acetyltransferase that targets signaling components of innate immunity and prevents their activation. Here we show that HopZ1a, from the phytopathogen Pseudomonas syringae is an acetyltransferase that binds plant tubulin. Like YopJ, the eukaryotic cofactor phytic acid activates the acetyltransferase activity of HopZ1a. In addition, we demonstrate that activated HopZ1a can acetylate tubulin, a major constituent of the eukaryotic cytoskeleton. In plants, activated HopZ1a causes a dramatic destruction of microtubule networks, inhibits protein secretion, and ultimately suppresses cell wall-mediated defense. Our study emphasizes the functional diversification of this important type III effector family in plant and animal hosts using a conserved acetyltransferase activity.
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Affiliation(s)
- Amy Huei-Yi Lee
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
| | - Brenden Hurley
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Corinna Felsensteiner
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
| | - Carmen Yea
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | | | - Verena Bartetzko
- Institut für Biologie, Lehrstuhl für Biochemie, Friedrich Alexander Universität Erlangen-Nürnberg, Germany
| | - Pauline W. Wang
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
| | - Van Quach
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Jennifer D. Lewis
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Yulu C. Liu
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Frederik Börnke
- Institut für Biologie, Lehrstuhl für Biochemie, Friedrich Alexander Universität Erlangen-Nürnberg, Germany
| | - Stephane Angers
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Andrew Wilde
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - David S. Guttman
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (DSG); (DD)
| | - Darrell Desveaux
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
- Centre for the Analysis of Genome Evolution & Function, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (DSG); (DD)
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Li J, Wang X, Qin T, Zhang Y, Liu X, Sun J, Zhou Y, Zhu L, Zhang Z, Yuan M, Mao T. MDP25, a novel calcium regulatory protein, mediates hypocotyl cell elongation by destabilizing cortical microtubules in Arabidopsis. THE PLANT CELL 2011; 23:4411-27. [PMID: 22209764 PMCID: PMC3269874 DOI: 10.1105/tpc.111.092684] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The regulation of hypocotyl elongation is important for plant growth. Microtubules play a crucial role during hypocotyl cell elongation. However, the molecular mechanism underlying this process is not well understood. In this study, we describe a novel Arabidopsis thaliana microtubule-destabilizing protein 25 (MDP25) as a negative regulator of hypocotyl cell elongation. We found that MDP25 directly bound to and destabilized microtubules to enhance microtubule depolymerization in vitro. The seedlings of mdp25 mutant Arabidopsis lines had longer etiolated hypocotyls. In addition, MDP25 overexpression resulted in significant overall shortening of hypocotyl cells, which exhibited destabilized cortical microtubules and abnormal cortical microtubule orientation, suggesting that MDP25 plays a crucial role in the negative regulation of hypocotyl cell elongation. Although MDP25 localized to the plasma membrane under normal conditions, increased calcium levels in cells caused MDP25 to partially dissociate from the plasma membrane and move into the cytosol. Cellular MDP25 bound to and destabilized cortical microtubules, resulting in their reorientation, and subsequently inhibited hypocotyl cell elongation. Our results suggest that MDP25 exerts its function on cortical microtubules by responding to cytoplasmic calcium levels to mediate hypocotyl cell elongation.
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28
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Centrosomes, microtubules and neuronal development. Mol Cell Neurosci 2011; 48:349-58. [DOI: 10.1016/j.mcn.2011.05.004] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 05/12/2011] [Accepted: 05/15/2011] [Indexed: 11/24/2022] Open
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Liu P, Qi M, Xue X, Ren H. Dynamics and functions of the actin cytoskeleton during the plant cell cycle. ACTA ACUST UNITED AC 2011. [DOI: 10.1007/s11434-011-4801-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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30
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Ambrose C, Allard JF, Cytrynbaum EN, Wasteneys GO. A CLASP-modulated cell edge barrier mechanism drives cell-wide cortical microtubule organization in Arabidopsis. Nat Commun 2011; 2:430. [PMID: 21847104 PMCID: PMC3265373 DOI: 10.1038/ncomms1444] [Citation(s) in RCA: 188] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2011] [Accepted: 07/20/2011] [Indexed: 11/09/2022] Open
Abstract
It is well known that the parallel order of microtubules in the plant cell cortex defines the direction of cell expansion, yet it remains unclear how microtubule orientation is controlled, especially on a cell-wide basis. Here we show through 4D imaging and computational modelling that plant cell polyhedral geometry provides spatial input that determines array orientation and heterogeneity. Microtubules depolymerize when encountering sharp cell edges head-on, whereas those oriented parallel to those sharp edges remain. Edge-induced microtubule depolymerization, however, is overcome by the microtubule-associated protein CLASP, which accumulates at specific cell edges, enables microtubule growth around sharp edges and promotes formation of microtubule bundles that span adjacent cell faces. By computationally modelling dynamic 'microtubules on a cube' with edges differentially permissive to microtubule passage, we show that the CLASP-edge complex is a 'tuneable' microtubule organizer, with the inherent flexibility to generate the numerous cortical array patterns observed in nature.
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Affiliation(s)
- Chris Ambrose
- Department of Botany, The University of British Columbia, Vancouver, British Columbia, V6T 1Z4 Canada
| | - Jun F. Allard
- Department of Mathematics, The University of British Columbia, Vancouver, British Columbia, V6T 1Z4 Canada
| | - Eric N. Cytrynbaum
- Department of Mathematics, The University of British Columbia, Vancouver, British Columbia, V6T 1Z4 Canada
| | - Geoffrey O. Wasteneys
- Department of Botany, The University of British Columbia, Vancouver, British Columbia, V6T 1Z4 Canada
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31
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Deinum EE, Tindemans SH, Mulder BM. Taking directions: the role of microtubule-bound nucleation in the self-organization of the plant cortical array. Phys Biol 2011; 8:056002. [PMID: 21791726 DOI: 10.1088/1478-3975/8/5/056002] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The highly aligned cortical microtubule array of interphase plant cells is a key regulator of anisotropic cell expansion. Recent computational and analytical work has shown that the non-equilibrium self-organization of this structure can be understood on the basis of experimentally observed collisional interactions between dynamic microtubules attached to the plasma membrane. Most of these approaches assumed that new microtubules are homogeneously and isotropically nucleated on the cortical surface. Experimental evidence, however, shows that nucleation mostly occurs from other microtubules and under specific relative angles. Here, we investigate the impact of directed microtubule-bound nucleations on the alignment process using computer simulations. The results show that microtubule-bound nucleations can increase the degree of alignment achieved, decrease the timescale of the ordering process and widen the regime of dynamic parameters for which the system can self-organize. We establish that the major determinant of this effect is the degree of co-alignment of the nucleations with the parent microtubule. The specific role of sideways branching nucleations appears to allow stronger alignment while maintaining a measure of overall spatial homogeneity. Finally, we investigate the suggestion that observed persistent rotation of microtubule domains can be explained through a handedness bias in microtubule-bound nucleations, showing that this is possible only for an extreme bias and over a limited range of parameters.
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Affiliation(s)
- Eva E Deinum
- Department of Biomolecular Systems, FOM institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.
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32
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The Preprophase Band and Division Site Determination in Land Plants. THE PLANT CYTOSKELETON 2011. [DOI: 10.1007/978-1-4419-0987-9_7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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33
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Mirabet V, Das P, Boudaoud A, Hamant O. The role of mechanical forces in plant morphogenesis. ANNUAL REVIEW OF PLANT BIOLOGY 2011; 62:365-85. [PMID: 21332360 DOI: 10.1146/annurev-arplant-042110-103852] [Citation(s) in RCA: 103] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The shape of an organism relies on a complex network of genetic regulations and on the homeostasis and distribution of growth factors. In parallel to the molecular control of growth, shape changes also involve major changes in structure, which by definition depend on the laws of mechanics. Thus, to understand morphogenesis, scientists have turned to interdisciplinary approaches associating biology and physics to investigate the contribution of mechanical forces in morphogenesis, sometimes re-examining theoretical concepts that were laid out by early physiologists. Major advances in the field have notably been possible thanks to the development of computer simulations and live quantitative imaging protocols in recent years. Here, we present the mechanical basis of shape changes in plants, focusing our discussion on undifferentiated tissues. How can growth be translated into a quantified geometrical output? What is the mechanical basis of cell and tissue growth? What is the contribution of mechanical forces in patterning?
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Affiliation(s)
- Vincent Mirabet
- INRA, CNRS, ENS, Université de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
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34
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Goodwin SS, Vale RD. Patronin regulates the microtubule network by protecting microtubule minus ends. Cell 2010; 143:263-74. [PMID: 20946984 DOI: 10.1016/j.cell.2010.09.022] [Citation(s) in RCA: 187] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 07/12/2010] [Accepted: 09/13/2010] [Indexed: 11/18/2022]
Abstract
Tubulin assembles into microtubule polymers that have distinct plus and minus ends. Most microtubule plus ends in living cells are dynamic; the transitions between growth and shrinkage are regulated by assembly-promoting and destabilizing proteins. In contrast, minus ends are generally not dynamic, suggesting their stabilization by some unknown protein. Here, we have identified Patronin (also known as ssp4) as a protein that stabilizes microtubule minus ends in Drosophila S2 cells. In the absence of Patronin, minus ends lose subunits through the actions of the Kinesin-13 microtubule depolymerase, leading to a sparse interphase microtubule array and short, disorganized mitotic spindles. In vitro, the selective binding of purified Patronin to microtubule minus ends is sufficient to protect them against Kinesin-13-induced depolymerization. We propose that Patronin caps and stabilizes microtubule minus ends, an activity that serves a critical role in the organization of the microtubule cytoskeleton.
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Affiliation(s)
- Sarah S Goodwin
- The Howard Hughes Medical Institute and Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158-2200, USA
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35
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Fache V, Gaillard J, Van Damme D, Geelen D, Neumann E, Stoppin-Mellet V, Vantard M. Arabidopsis kinetochore fiber-associated MAP65-4 cross-links microtubules and promotes microtubule bundle elongation. THE PLANT CELL 2010; 22:3804-15. [PMID: 21119057 PMCID: PMC3015114 DOI: 10.1105/tpc.110.080606] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 10/27/2010] [Accepted: 11/10/2010] [Indexed: 05/02/2023]
Abstract
The acentrosomal plant mitotic spindle is uniquely structured in that it lacks opposing centrosomes at its poles and is equipped with a connective preprophase band that regulates the spatial framework for spindle orientation and mobility. These features are supported by specialized microtubule-associated proteins and motors. Here, we show that Arabidopsis thaliana MAP65-4, a non-motor microtubule associated protein (MAP) that belongs to the evolutionarily conserved MAP65 family, specifically associates with the forming mitotic spindle during prophase and with the kinetochore fibers from prometaphase to the end of anaphase. In vitro, MAP65-4 induces microtubule (MT) bundling through the formation of cross-bridges between adjacent MTs both in polar and antipolar orientations. The association of MAP65-4 with an MT bundle is concomitant with its elongation. Furthermore, MAP65-4 modulates the MT dynamic instability parameters of individual MTs within a bundle, mainly by decreasing the frequency of catastrophes and increasing the frequency of rescue events, and thereby supports the progressive lengthening of MT bundles over time. These properties are in line with its role of initiating kinetochore fibers during prospindle formation.
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Affiliation(s)
- Vincent Fache
- Institut de Recherches en Technologies et Sciences pour le Vivant, Commissariat à l’Energie Atomique/Centre National de la Recherche Scientifique/Institut National de la Recherche Agronomique/Université Joseph Fourier, 38054 Grenoble, France
| | - Jérémie Gaillard
- Institut de Recherches en Technologies et Sciences pour le Vivant, Commissariat à l’Energie Atomique/Centre National de la Recherche Scientifique/Institut National de la Recherche Agronomique/Université Joseph Fourier, 38054 Grenoble, France
| | - Daniel Van Damme
- Department of Plant Systems Biology, VIB, B-9052 Ghent, Belgium
- Department of Plant Biotechnology and Genetics, Ghent University, B-9052 Ghent, Belgium
| | - Danny Geelen
- Department of Plant Production, Ghent University, B-9000 Ghent, Belgium
| | - Emmanuelle Neumann
- Institut de Biologie Structurale, Commissariat à l’Energie Atomique/Centre National de la Recherche Scientifique/Université Joseph Fourier, 38027 Grenoble, France
| | - Virginie Stoppin-Mellet
- Institut de Recherches en Technologies et Sciences pour le Vivant, Commissariat à l’Energie Atomique/Centre National de la Recherche Scientifique/Institut National de la Recherche Agronomique/Université Joseph Fourier, 38054 Grenoble, France
| | - Marylin Vantard
- Institut de Recherches en Technologies et Sciences pour le Vivant, Commissariat à l’Energie Atomique/Centre National de la Recherche Scientifique/Institut National de la Recherche Agronomique/Université Joseph Fourier, 38054 Grenoble, France
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36
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Mutations of cellulose synthase (CESA1) phosphorylation sites modulate anisotropic cell expansion and bidirectional mobility of cellulose synthase. Proc Natl Acad Sci U S A 2010; 107:17188-93. [PMID: 20855602 DOI: 10.1073/pnas.1012348107] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The CESA1 component of cellulose synthase is phosphorylated at sites clustered in two hypervariable regions of the protein. Mutations of the phosphorylated residues to Ala (A) or Glu (E) alter anisotropic cell expansion and cellulose synthesis in rapidly expanding roots and hypocotyls. Expression of T166E, S686E, or S688E mutants of CESA1 fully rescued the temperature sensitive cesA1-1 allele (rsw1) at a restrictive temperature whereas mutations to A at these positions caused defects in anisotropic cell expansion. However, mutations to E at residues surrounding T166 (i.e., S162, T165, and S167) caused opposite effects. Live-cell imaging of fluorescently labeled CESA showed close correlations between tissue or cell morphology and patterns of bidirectional motility of CESA complexes in the plasma membrane. In the WT, CESA complexes moved at similar velocities in both directions along microtubule tracks. By contrast, the rate of movement of CESA particles was directionally asymmetric in mutant lines that exhibited abnormal tissue or cell expansion, and the asymmetry was removed upon depolymerizing microtubules with oryzalin. This suggests that phosphorylation of CESA differentially affects a polar interaction with microtubules that may regulate the length or quantity of a subset of cellulose microfibrils and that this, in turn, alters microfibril structure in the primary cell wall resulting in or contributing to the observed defect in anisotropic cell expansion.
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37
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Abstract
Microtubules assemble into arrays of bundled filaments that are critical for multiple steps in cell division, including anaphase and cytokinesis. Recent structural and functional studies, including two papers in this issue of Cell (Bieling et al., 2010; Subramanian et al., 2010), demonstrate how the MAP65 protein PRC1 crosslinks microtubules and cooperates with kinesin motors to control the dynamics and size of bundled regions.
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Affiliation(s)
- Claire E Walczak
- Medical Sciences, Indiana University, Bloomington, IN 47405, USA.
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38
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Wood Cell-Wall Structure Requires Local 2D-Microtubule Disassembly by a Novel Plasma Membrane-Anchored Protein. Curr Biol 2010; 20:1197-202. [DOI: 10.1016/j.cub.2010.05.038] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2010] [Revised: 04/13/2010] [Accepted: 05/03/2010] [Indexed: 11/24/2022]
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39
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Pytela J, Kato T, Hashimoto T. Mitogen-activated protein kinase phosphatase PHS1 is retained in the cytoplasm by nuclear extrusion signal-dependent and independent mechanisms. PLANTA 2010; 231:1311-22. [PMID: 20224945 DOI: 10.1007/s00425-010-1135-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2009] [Accepted: 02/22/2010] [Indexed: 05/13/2023]
Abstract
The organization of plant microtubule arrays is thought to be regulated by phosphorylation and other signaling cascades, but the molecular components involved are largely unknown. We have previously found that a dominant missense mutation (phs1-1) in a putative kinase-docking motif of an Arabidopsis PHS1 phosphatase, which belongs to the mitogen-activated protein kinase phosphatase (MKP) family, compromises the stability of cortical microtubules. We here report that suppressor screening of phs1-1 recovered several intragenic recessive mutations in PHS1. In contrast to our previous report, null alleles of PHS1 were almost indistinguishable from the wild type in morphology, but their roots skewed to the abnormal direction when grew in the presence of low doses of a microtubule-destabilizing drug. PHS1 is mainly expressed in elongating cells, where the protein was distributed in the cytoplasm, predominantly in a microsomal fraction. Recruitment of green fluorescent protein-tagged PHS1 in endomembrane aggregates after treatment with brefeldin A or in an endomembrane-organization mutant suggests that an association with endomembranes retains PHS1 in the cytoplasm. A nuclear export signal identified in the C-terminal tail also contributes to the robust cytoplasmic retention of PHS1.
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Affiliation(s)
- Jaromir Pytela
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, 630-0192 Nara, Japan
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40
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Szymanski DB, Cosgrove DJ. Dynamic coordination of cytoskeletal and cell wall systems during plant cell morphogenesis. Curr Biol 2010; 19:R800-11. [PMID: 19906582 DOI: 10.1016/j.cub.2009.07.056] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Underlying the architectural complexity of plants are diverse cell types that, under the microscope, easily reveal relationships between cell structure and specialized functions. Much less obvious are the mechanisms by which the cellular growth machinery and mechanical properties of the cell interact to dictate cell shape. The recent combined use of mutants, genomic analyses, sophisticated spectroscopies, and live cell imaging is providing new insight into how cytoskeletal systems and cell wall biosynthetic activities are integrated during morphogenesis. The purpose of this review is to discuss the unique geometric properties and physical processes that regulate plant cell expansion, then to overlay on this mechanical system some of the recent discoveries about the protein machines and cellular polymers that regulate cell shape. In the end, we hope to make clear that there are many interesting opportunities to develop testable mathematical models that improve our understanding of how subcellular structures, protein motors, and extracellular polymers can exert effects at spatial scales that span cells, tissues, and organs.
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Affiliation(s)
- Daniel B Szymanski
- Department of Agronomy, Lily Hall of Life Sciences, 915 West State Street, Purdue University, West Lafayette, IN 47907, USA.
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41
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Abstract
Morphogenesis in living organisms relies on the integration of both biochemical and mechanical signals. During the last decade, attention has been mainly focused on the role of biochemical signals in patterning and morphogenesis, leaving the contribution of mechanics largely unexplored. Fortunately, the development of new tools and approaches has made it possible to re-examine these processes. In plants, shape is defined by two local variables: growth rate and growth direction. At the level of the cell, these variables depend on both the cell wall and turgor pressure. Multidisciplinary approaches have been used to understand how these cellular processes are integrated in the growing tissues. These include quantitative live imaging to measure growth rate and direction in tissues with cellular resolution. In parallel, stress patterns have been artificially modified and their impact on strain and cell behavior been analysed. Importantly, computational models based on analogies with continuum mechanics systems have been useful in interpreting the results. In this review, we will discuss these issues focusing on the shoot apical meristem, a population of stem cells that is responsible for the initiation of the aerial organs of the plant.
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Affiliation(s)
- Olivier Hamant
- Laboratoire de Reproduction et Développement des Plantes, INRA, CNRS, ENS, Université de Lyon, Lyon Cedex 07, France.
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42
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Nakamura M, Hashimoto T. A mutation in the Arabidopsis γ-tubulin-containing complex causes helical growth and abnormal microtubule branching. J Cell Sci 2009; 122:2208-17. [DOI: 10.1242/jcs.044131] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Plant cortical microtubules are mainly nucleated on previously established microtubules, grow at a narrow range of angles to the wall of mother microtubules, and eventually are released from the nucleation sites. These nucleation events are thought to be regulated by γ-tubulin-containing complexes. We here show that a null mutation of Arabidopsis GCP2, a core subunit of the γ-tubulin-containing complex, severely impaired the development of male and female gametophytes. However, a missense mutation in the conserved grip1 motif, called spiral3, caused a left-handed helical organization of cortical microtubule arrays, and severe right-handed helical growth. The spiral3 mutation compromises interaction between GCP2 and GCP3, another subunit of the complex, in yeast. In the spiral3 mutant, microtubule dynamics and nucleation efficiency were not markedly affected, but nucleating angles were wider and more divergently distributed. A spiral3 katanin double mutant had swollen and twisted epidermal cells, and showed that the microtubule minus ends were not released from the nucleation sites, although the nucleating angles distributed in a similar manner to those in spiral3. These results show that Arabidopsis GCP2 has an important role in precisely positioning the γ-tubulin-containing complex on pre-existing microtubules and in the proper organization of cortical arrays.
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Affiliation(s)
- Masayoshi Nakamura
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
| | - Takashi Hashimoto
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara 630-0192, Japan
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Andreeva Z, Ho AYY, Barthet MM, Potocký M, Bezvoda R, Žárský V, Marc J. Phospholipase D family interactions with the cytoskeleton: isoform delta promotes plasma membrane anchoring of cortical microtubules. FUNCTIONAL PLANT BIOLOGY : FPB 2009; 36:600-612. [PMID: 32688673 DOI: 10.1071/fp09024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Accepted: 04/25/2009] [Indexed: 05/06/2023]
Abstract
Phospholipase D (PLD) is a key enzyme in signal transduction - mediating plant responses to various environmental stresses including drought and salinity. Isotype PLDδ interacts with the microtubule cytoskeleton, although it is unclear if, or how, each of the 12 PLD isotypes in Arabidopsis may be involved mechanistically. We employed RNA interference in epidermal cells of Allium porrum L. (leek) leaves, in which the developmental reorientation of cortical microtubule arrays to a longitudinal direction is highly sensitive to experimental manipulation. Using particle bombardment and transient transformation with synthetic siRNAs targeting AtPLDα, β, γ, δ, ॉ and ζ, we examined the effect of 'cross-target' silencing orthologous A. porrum genes on microtubule reorientation dynamics during cell elongation. Co-transformation of individual siRNAs together with a GFP-MBD microtubule-reporter gene revealed that siRNAs targeting AtPLDδ promoted, whereas siRNAs targeting AtPLDβ and γ reduced, longitudinal microtubule orientation in A. porrum. These PLD isotypes, therefore, interact, directly or indirectly, with the cytoskeleton and the microtubule-plasma membrane interface. The unique response of PLDδ to silencing, along with its exclusive localisation to the plasma membrane, indicates that this isotype is specifically involved in promoting microtubule-membrane anchorage.
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Affiliation(s)
- Zornitza Andreeva
- School of Biological Sciences, Macleay Building A12, University of Sydney, Sydney, NSW 2006, Australia
| | - Angela Y Y Ho
- School of Biological Sciences, Macleay Building A12, University of Sydney, Sydney, NSW 2006, Australia
| | - Michelle M Barthet
- School of Biological Sciences, Macleay Building A12, University of Sydney, Sydney, NSW 2006, Australia
| | - Martin Potocký
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Radek Bezvoda
- Department of Plant Physiology, Faculty of Science, Charles University, Viničná 5, 128 44 Prague 2, Czech Republic
| | - Viktor Žárský
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, Rozvojová 263, 165 02 Prague 6, Czech Republic
| | - Jan Marc
- School of Biological Sciences, Macleay Building A12, University of Sydney, Sydney, NSW 2006, Australia
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44
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Arabidopsis cortical microtubules position cellulose synthase delivery to the plasma membrane and interact with cellulose synthase trafficking compartments. Nat Cell Biol 2009; 11:797-806. [PMID: 19525940 DOI: 10.1038/ncb1886] [Citation(s) in RCA: 461] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Accepted: 05/20/2009] [Indexed: 01/10/2023]
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Braun M, Drummond DR, Cross RA, McAinsh AD. The kinesin-14 Klp2 organizes microtubules into parallel bundles by an ATP-dependent sorting mechanism. Nat Cell Biol 2009; 11:724-30. [PMID: 19430466 DOI: 10.1038/ncb1878] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Accepted: 02/24/2009] [Indexed: 11/08/2022]
Abstract
The dynamic organization of microtubules into parallel arrays allows interphase cells to set up multi-lane highways for intracellular transport and M-phase cells to build the mitotic and meiotic spindles. Here we show that a minimally reconstituted system composed of Klp2, a kinesin-14 from the fission yeast Schizosaccharomyces pombe, together with microtubules assembled from purified S. pombe tubulin, autonomously assembles bundles of parallel microtubules. Bundles form by an ATP-dependent sorting mechanism that requires the full-length Klp2 motor. By this mechanism, antiparallel-overlapped microtubules slide over one another until they dissociate from the bundles, whereas parallel-overlapped microtubules are selectively trapped by an energy-dissipating force-balance mechanism. Klp2-driven microtubule sorting provides a robust pathway for the organization of microtubules into parallel arrays. In vivo evidence indicates that Klp2 is required for the proper organization of S. pombe interphase microtubules into bipolar arrays of parallel-overlapped microtubules, suggesting that kinesin-14-dependent microtubule sorting may have wide biological importance.
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Affiliation(s)
- Marcus Braun
- Chromosome Segregation Laboratory, Marie Curie Research Institute, The Chart, Oxted, RH8 0TL, Surrey, UK
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Müller S, Wright AJ, Smith LG. Division plane control in plants: new players in the band. Trends Cell Biol 2009; 19:180-8. [PMID: 19285867 DOI: 10.1016/j.tcb.2009.02.002] [Citation(s) in RCA: 90] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2008] [Revised: 02/02/2009] [Accepted: 02/02/2009] [Indexed: 01/03/2023]
Abstract
Unique mechanisms are used to orient cell division planes in plants. A cortical ring of cytoskeletal filaments called the preprophase band (PPB) predicts the future division plane during G2 and is disassembled as the mitotic spindle forms, leaving behind a 'cortical division site' (CDS) that guides the placement of the new cell wall (cell plate) during cytokinesis. The molecular features of the CDS have remained elusive for decades. Recently, a few proteins have at last been identified that are specifically localized to or excluded from the CDS and that participate in the orientation, attachment or maturation of cell plates. Recent progress has also been made in identifying proteins needed for PPB formation and thus for division plane establishment.
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Affiliation(s)
- Sabine Müller
- Zentrum für Molekularbiologie der Pflanzen, Universität Tübingen, Auf der Morgenstelle, Germany.
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Affiliation(s)
- Karen Lyle
- Department of Cell and Tissue Biology, University of California, San Francisco, CA 94143, USA
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48
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Spatial organization of plant cortical microtubules: close encounters of the 2D kind. Trends Cell Biol 2009; 19:62-71. [PMID: 19144522 DOI: 10.1016/j.tcb.2008.11.004] [Citation(s) in RCA: 129] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 11/24/2008] [Accepted: 11/27/2008] [Indexed: 01/22/2023]
Abstract
The shape of plant cells depends on cortical microtubules. Their freedom from central microtubule organizing centres provides a powerful experimental system to study microtubule self-organization. New ideas have emerged from live-cell imaging of microtubules, particularly in the model system Arabidopsis thaliana, revealing the importance of encounters between microtubules in driving self-organization. Encounters are modulated by intrinsic microtubule-assembly dynamics, along with polymer activities that include cortical attachment, bundling and severing. Balancing the activities of microtubule-associated proteins (such as MOR1, CLASP, MAP65s and katanins) that control these processes is crucial for fine-tuning the organization of microtubule arrays. Too much or too little of any given activity tips the balance, with often dramatic effects on array organization, cell morphogenesis and even organ chirality.
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Bratman SV, Chang F. Mechanisms for maintaining microtubule bundles. Trends Cell Biol 2008; 18:580-6. [PMID: 18951798 DOI: 10.1016/j.tcb.2008.09.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Revised: 09/04/2008] [Accepted: 09/05/2008] [Indexed: 10/21/2022]
Abstract
The dynamics of microtubules (MTs) are crucial to many of their functions. Certain MT structures, such as the mitotic spindle apparatus, exhibit high MT turnover yet maintain their mass stably through long periods of time. Here, we highlight what are emerging as two important mechanisms for maintaining MT bundles: the first, MT nucleation from pre-existing MTs by means of gamma-tubulin-containing complexes; and the second, MT 'rescue' by the stabilizing protein CLASP. As examples, we describe recent advances in understanding the assembly and maintenance of simple MT bundles in fission yeast and plant cells, which have implications for the bundles of the animal mitotic spindle.
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Affiliation(s)
- Scott V Bratman
- Microbiology Department, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA
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Sainsbury F, Collings DA, Mackun K, Gardiner J, Harper JDI, Marc J. Developmental reorientation of transverse cortical microtubules to longitudinal directions: a role for actomyosin-based streaming and partial microtubule-membrane detachment. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2008; 56:116-31. [PMID: 18557839 DOI: 10.1111/j.1365-313x.2008.03574.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Transversely oriented cortical microtubules in elongating cells typically reorient themselves towards longitudinal directions at the end of cell elongation. We have investigated the reorientation mechanism along the outer epidermal wall in maturing leek (Allium porrum L.) leaves using a GFP-MBD microtubule reporter gene and fluorescence microscopy. Incubating leaf segments for 14-18 h with the anti-actin or anti-actomyosin agents, 20 microm cytochalasin D or 20 mM 2,3-butanedione monoxime, inhibited the normal developmental reorientation of microtubules to the longitudinal direction. Observation of living cells revealed a small subpopulation of microtubules with their free ends swinging into oblique or longitudinal directions, before continuing to assemble in the new direction. Electron microscopy confirmed that longitudinal microtubules are partly detached from the plasma membrane. Incubating leaf segments with 0.2% 1 degree-butanol, an activator of phospholipase D, which has been implicated in plasma membrane-microtubule anchoring, promoted the reorientation, presumably by promoting microtubule detachment from the membrane. Stabilizing microtubules with 10 microm taxol also promoted longitudinal orientation, even in the absence of cytoplasmic streaming. These results were consistent with confocal microscopy of live cells before and after drug treatments, which also revealed that the slow (days) global microtubule reorientation is superimposed over short-term (hours) regional cycling in a clockwise and an anti-clockwise direction. We propose that partial detachment of transverse microtubules from the plasma membrane in maturing cells exposes them to hydrodynamic forces of actomyosin-driven cytoplasmic streaming, which bends or shifts pivoting microtubules into longitudinal directions, and thus provides an impetus to push microtubule dynamics in the new direction.
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Affiliation(s)
- Frank Sainsbury
- School of Biological Sciences, University of Sydney, Sydney, NSW 2006, Australia
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