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Li J, Szymanski DB, Kim T. Probing stress-regulated ordering of the plant cortical microtubule array via a computational approach. BMC PLANT BIOLOGY 2023; 23:308. [PMID: 37291489 DOI: 10.1186/s12870-023-04252-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 04/27/2023] [Indexed: 06/10/2023]
Abstract
BACKGROUND Morphological properties of tissues and organs rely on cell growth. The growth of plant cells is determined by properties of a tough outer cell wall that deforms anisotropically in response to high turgor pressure. Cortical microtubules bias the mechanical anisotropy of a cell wall by affecting the trajectories of cellulose synthases in the wall that polymerize cellulose microfibrils. The microtubule cytoskeleton is often oriented in one direction at cellular length-scales to regulate growth direction, but the means by which cellular-scale microtubule patterns emerge has not been well understood. Correlations between the microtubule orientation and tensile forces in the cell wall have often been observed. However, the plausibility of stress as a determining factor for microtubule patterning has not been directly evaluated to date. RESULTS Here, we simulated how different attributes of tensile forces in the cell wall can orient and pattern the microtubule array in the cortex. We implemented a discrete model with transient microtubule behaviors influenced by local mechanical stress in order to probe the mechanisms of stress-dependent patterning. Specifically, we varied the sensitivity of four types of dynamic behaviors observed on the plus end of microtubules - growth, shrinkage, catastrophe, and rescue - to local stress. Then, we evaluated the extent and rate of microtubule alignments in a two-dimensional computational domain that reflects the structural organization of the cortical array in plant cells. CONCLUSION Our modeling approaches reproduced microtubule patterns observed in simple cell types and demonstrated that a spatial variation in the magnitude and anisotropy of stress can mediate mechanical feedback between the wall and of the cortical microtubule array.
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Affiliation(s)
- Jing Li
- Weldon School of Biomedical Engineering, Purdue University, 206 S Martin Jischke Dr, West Lafayette, IN, 47907, USA
| | - Daniel B Szymanski
- Botany and Plant Pathology, Biological Sciences, Purdue University, 915 West State Street, West Lafayette, IN, 47907, USA.
| | - Taeyoon Kim
- Weldon School of Biomedical Engineering, Purdue University, 206 S Martin Jischke Dr, West Lafayette, IN, 47907, USA.
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2
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Documentation of Microtubule Collisions with Myosin VIII ATM1 Containing Membrane-Associated Structures. Methods Mol Biol 2023; 2604:77-88. [PMID: 36773226 DOI: 10.1007/978-1-0716-2867-6_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
Collisions of microtubules with membrane-associated structures containing myosin VIII were recently described, and these data suggested that such collisions can happen between microtubules and other membrane-associated proteins. Such collisions may contribute to a coordinated organization between microtubules and membrane-associated proteins especially in cases of low lateral diffusion rates of the protein. Coordinated organization of cortical cytoskeleton and membrane structures can have consequences on membrane compartmentalization and downstream signaling. Here we describe a way to analyze collisions of cortical microtubules and membrane-associated proteins by confocal microscopy. In addition, we describe a tool to measure and quantify these collisions.
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3
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Wang LM, Goodman MB, Kuhl E. Image-based axon model highlights heterogeneity in initiation of damage. Biophys J 2023; 122:9-19. [PMID: 36461640 PMCID: PMC9822833 DOI: 10.1016/j.bpj.2022.11.2946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 07/29/2022] [Accepted: 11/28/2022] [Indexed: 12/03/2022] Open
Abstract
Head injury simulations predict the occurrence of traumatic brain injury by placing a threshold on the calculated strains for axon tracts within the brain. However, a current roadblock to accurate injury prediction is the selection of an appropriate axon damage threshold. While several computational studies have used models of the axon cytoskeleton to investigate damage initiation, these models all employ an idealized, homogeneous axonal geometry. This homogeneous geometry with regularly spaced microtubules, evenly distributed throughout the model, overestimates axon strength because, in reality, the axon cytoskeleton is heterogeneous. In the heterogeneous cytoskeleton, the weakest cross section determines the initiation of failure, but these weak spots are not present in a homogeneous model. Addressing one source of heterogeneity in the axon cytoskeleton, we present a new semiautomated image analysis pipeline for using serial-section transmission electron micrographs to reconstruct the microtubule geometry of an axon. The image analysis procedure locates microtubules within the images, traces them throughout the image stack, and reconstructs the microtubule structure as a finite element mesh. We demonstrate the image analysis approach using a C. elegans touch receptor neuron due to the availability of high-quality serial-section transmission electron micrograph data sets. The results of the analysis highlight the heterogeneity of the microtubule structure in the spatial variation of both microtubule number and length. Simulations comparing this image-based geometry with homogeneous geometries show that structural heterogeneity in the image-based model creates significant spatial variation in deformation. The homogeneous geometries, on the other hand, deform more uniformly. Since no single homogeneous model can replicate the mechanical behavior of the image-based model, our results argue that heterogeneity in axon microtubule geometry should be considered in determining accurate axon failure thresholds.
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Affiliation(s)
- Lucy M Wang
- Department of Mechanical Engineering, Stanford University, Stanford, California.
| | - Miriam B Goodman
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California
| | - Ellen Kuhl
- Department of Mechanical Engineering, Stanford University, Stanford, California
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4
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Bar-Sinai S, Belausov E, Dwivedi V, Sadot E. Collisions of Cortical Microtubules with Membrane Associated Myosin VIII Tail. Cells 2022; 11:cells11010145. [PMID: 35011707 PMCID: PMC8750215 DOI: 10.3390/cells11010145] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Revised: 12/26/2021] [Accepted: 12/29/2021] [Indexed: 02/04/2023] Open
Abstract
The distribution of myosin VIII ATM1 tail in association with the plasma membrane is often observed in coordination with that of cortical microtubules (MTs). The prevailing hypothesis is that coordination between the organization of cortical MTs and proteins in the membrane results from the inhibition of free lateral diffusion of the proteins by barriers formed by MTs. Since the positioning of myosin VIII tail in the membrane is relatively stable, we ask: can it affect the organization of MTs? Myosin VIII ATM1 tail co-localized with remorin 6.6, the position of which in the plasma membrane is also relatively stable. Overexpression of myosin VIII ATM1 tail led to a larger fraction of MTs with a lower rate of orientation dispersion. In addition, collisions between MTs and cortical structures labeled by ATM1 tail or remorin 6.6 were observed. Collisions between EB1 labeled MTs and ATM1 tail clusters led to four possible outcomes: 1—Passage of MTs through the cluster; 2—Decreased elongation rate; 3—Disengagement from the membrane followed by a change in direction; and 4—retraction. EB1 tracks became straighter in the presence of ATM1 tail. Taken together, collisions of MTs with ATM1 tail labeled structures can contribute to their coordinated organization.
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5
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Chen J, Chu Z, Han H, Patterson E, Yu Q, Powles S. Diversity of α-tubulin transcripts in Lolium rigidum. PEST MANAGEMENT SCIENCE 2021; 77:970-977. [PMID: 32991064 DOI: 10.1002/ps.6109] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 09/18/2020] [Accepted: 09/29/2020] [Indexed: 05/24/2023]
Abstract
BACKGROUND Tubulin, the target site of dinitroaniline herbicides, is encoded by small gene families in plants. To better characterize the mechanisms of target-site resistance to dinitroaniline herbicides in the globally important weedy species Lolium rigidum, attempts were made to amplify and sequence α-tubulin transcripts. RESULTS Four α-tubulin isoforms (TUA1, TUA2, TUA3 and TUA4) were identified in L. rigidum. Variations in the number and sequence of transcripts encoding these α-tubulin proteins were found in individuals from the two L. rigidum populations examined. Within and among populations, differences in the 5'- and 3'-untranslated regions of cDNA in TUA3 and TUA4 were identified. Furthermore, a novel double mutation, Arg-390-Cys+Asp-442-Glu, in the TUA3 transcript was identified and has the potential to confer dinitroaniline resistance. CONCLUSION This research reveals the complexity of the α-tubulin gene family in individuals/populations of the cross-pollinated weedy species L. rigidum, and highlights the need for better understanding of the molecular architecture of tubulin gene families for detecting resistance point mutations. Although TUA4 is a commonly expressed α-tubulin isoform containing most frequently reported resistance mutations, other mutant tubulin isoforms may also have a role in conferring dinitroaniline resistance.
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Affiliation(s)
- Jinyi Chen
- Australian Herbicide Resistance Initiative, School of Agriculture and Environment, University of Western Australia, Perth, Western Australia, Australia
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, USA
| | - Zhizhan Chu
- College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Heping Han
- Australian Herbicide Resistance Initiative, School of Agriculture and Environment, University of Western Australia, Perth, Western Australia, Australia
| | - Eric Patterson
- Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, USA
| | - Qin Yu
- Australian Herbicide Resistance Initiative, School of Agriculture and Environment, University of Western Australia, Perth, Western Australia, Australia
| | - Stephen Powles
- Australian Herbicide Resistance Initiative, School of Agriculture and Environment, University of Western Australia, Perth, Western Australia, Australia
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Yang Q, Wan X, Wang J, Zhang Y, Zhang J, Wang T, Yang C, Ye Z. The loss of function of HEL, which encodes a cellulose synthase interactive protein, causes helical and vine-like growth of tomato. HORTICULTURE RESEARCH 2020; 7:180. [PMID: 33328443 PMCID: PMC7603515 DOI: 10.1038/s41438-020-00402-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2020] [Revised: 07/21/2020] [Accepted: 07/27/2020] [Indexed: 05/08/2023]
Abstract
Helical growth is an economical way for plant to obtain resources. The classic microtubule-microfibril alignment model of Arabidopsis helical growth involves restriction of the appropriate orientation of cellulose microfibrils appropriately in the cell walls. However, the molecular mechanism underlying tomato helical growth remains unknown. Here, we identified a spontaneous tomato helical (hel) mutant with right-handed helical cotyledons and petals but left-handed helical stems and true leaves. Genetic analysis revealed that the hel phenotype was controlled by a single recessive gene. Using map-based cloning, we cloned the HEL gene, which encodes a cellulose interacting protein homologous to CSI1 of Arabidopsis. We identified a 27 bp fragment replacement that generated a premature stop codon. Transgenic experiments showed that the helical growth phenotype could be restored by the allele of this gene from wild-type Pyriforme. In contrast, the knockout mutation of HEL in Pyriforme via CRISPR/Cas9 resulted in helical growth. These findings shed light on the molecular control of the helical growth of tomato.
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Affiliation(s)
- Qihong Yang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Xiaoshuai Wan
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Jiaying Wang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Yuyang Zhang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Junhong Zhang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Taotao Wang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China
| | - Changxian Yang
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China.
| | - Zhibiao Ye
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Wuhan, 430070, China.
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True JH, Shaw SL. Exogenous Auxin Induces Transverse Microtubule Arrays Through TRANSPORT INHIBITOR RESPONSE1/AUXIN SIGNALING F-BOX Receptors. PLANT PHYSIOLOGY 2020; 182:892-907. [PMID: 31767691 PMCID: PMC6997688 DOI: 10.1104/pp.19.00928] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 11/10/2019] [Indexed: 05/12/2023]
Abstract
Auxin plays a central role in controlling plant cell growth and morphogenesis. Application of auxin to light-grown seedlings elicits both axial growth and transverse patterning of the cortical microtubule cytoskeleton in hypocotyl cells. Microtubules respond to exogenous auxin within 5 min, although repatterning of the array does not initiate until 30 min after application and is complete by 2 h. To examine the requirements for auxin-induced microtubule array patterning, we used an Arabidopsis (Arabidopsis thaliana) double auxin f-box (afb) receptor mutant, afb4-8 afb5-5, that responds to conventional auxin (indole-3-acetic acid) but has a strongly diminished response to the auxin analog, picloram. We show that 5 µm picloram induces immediate changes to microtubule density and later transverse microtubule patterning in wild-type plants, but does not cause microtubule array reorganization in the afb4-8 afb5-5 mutant. Additionally, a dominant mutant (axr2-1) for the auxin coreceptor AUXIN RESPONSIVE2 (AXR2) was strongly suppressed for auxin-induced microtubule array reorganization, providing additional evidence that auxin functions through a transcriptional pathway for transverse patterning. We observed that brassinosteroid application mimicked the auxin response, showing both early and late microtubule array effects, and induced transverse patterning in the axr2-1 mutant. Application of auxin to the brassinosteroid synthesis mutant, diminuto1, induced transverse array patterning but did not produce significant axial growth. Thus, exogenous auxin induces transverse microtubule patterning through the TRANSPORT INHIBITOR 1/AUXIN F-BOX (TIR1/AFB) transcriptional pathway and can act independently of brassinosteroids.
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Affiliation(s)
- Jillian H True
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Sidney L Shaw
- Department of Biology, Indiana University, Bloomington, Indiana 47405
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8
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Zhong R, Cui D, Ye ZH. Secondary cell wall biosynthesis. THE NEW PHYTOLOGIST 2019; 221:1703-1723. [PMID: 30312479 DOI: 10.1111/nph.15537] [Citation(s) in RCA: 142] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2018] [Accepted: 09/28/2018] [Indexed: 05/19/2023]
Abstract
Contents Summary 1703 I. Introduction 1703 II. Cellulose biosynthesis 1705 III. Xylan biosynthesis 1709 IV. Glucomannan biosynthesis 1713 V. Lignin biosynthesis 1714 VI. Concluding remarks 1717 Acknowledgements 1717 References 1717 SUMMARY: Secondary walls are synthesized in specialized cells, such as tracheary elements and fibers, and their remarkable strength and rigidity provide strong mechanical support to the cells and the plant body. The main components of secondary walls are cellulose, xylan, glucomannan and lignin. Biochemical, molecular and genetic studies have led to the discovery of most of the genes involved in the biosynthesis of secondary wall components. Cellulose is synthesized by cellulose synthase complexes in the plasma membrane and the recent success of in vitro synthesis of cellulose microfibrils by a single recombinant cellulose synthase isoform reconstituted into proteoliposomes opens new doors to further investigate the structure and functions of cellulose synthase complexes. Most genes involved in the glycosyl backbone synthesis, glycosyl substitutions and acetylation of xylan and glucomannan have been genetically characterized and the biochemical properties of some of their encoded enzymes have been investigated. The genes and their encoded enzymes participating in monolignol biosynthesis and modification have been extensively studied both genetically and biochemically. A full understanding of how secondary wall components are synthesized will ultimately enable us to produce plants with custom-designed secondary wall composition tailored to diverse applications.
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Affiliation(s)
- Ruiqin Zhong
- Department of Plant Biology, University of Georgia, Athens, GA, 30602, USA
| | - Dongtao Cui
- Department of Chemistry, University of Georgia, Athens, GA, 30602, USA
| | - Zheng-Hua Ye
- Department of Plant Biology, University of Georgia, Athens, GA, 30602, USA
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Thoms D, Vineyard L, Elliott A, Shaw SL. CLASP Facilitates Transitions between Cortical Microtubule Array Patterns. PLANT PHYSIOLOGY 2018; 178:1551-1567. [PMID: 30327382 PMCID: PMC6288741 DOI: 10.1104/pp.18.00961] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 10/07/2018] [Indexed: 05/23/2023]
Abstract
Acentrosomal plant microtubule arrays form patterns at the cell cortex that influence cellular morphogenesis by templating the deposition of cell wall materials, but the molecular basis by which the microtubules form the cortical array patterns remains largely unknown. Loss of the Arabidopsis (Arabidopsis thaliana) microtubule-associated protein, CYTOPLASMIC LINKER ASSOCIATED PROTEIN (AtCLASP), results in cellular growth anisotropy defects in hypocotyl cells. We examined the microtubule array patterning in atclasp-1 null mutants and discovered a significant defect in the timing of transitions between array patterns but no substantive defect in the array patterns per se. Detailed analysis and computational modeling of the microtubule dynamics in two atclasp-1 fluorescent tubulin marker lines revealed marker-dependent effects on depolymerization and catastrophe frequency predicted to alter the steady-state microtubule population. Quantitative in vivo analysis of the underlying microtubule array architecture showed that AtCLASP is required to maintain the number of growing microtubule plus ends during transitions between array patterns. We propose that AtCLASP plays a critical role in cellular morphogenesis through actions on new microtubules that facilitate array transitions.
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Affiliation(s)
- David Thoms
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Laura Vineyard
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Andrew Elliott
- Department of Biology, Indiana University, Bloomington, Indiana 47405
| | - Sidney L Shaw
- Department of Biology, Indiana University, Bloomington, Indiana 47405
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Elliott A, Shaw SL. A Cycloheximide-Sensitive Step in Transverse Microtubule Array Patterning. PLANT PHYSIOLOGY 2018; 178:684-698. [PMID: 30154175 PMCID: PMC6181046 DOI: 10.1104/pp.18.00672] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Accepted: 08/19/2018] [Indexed: 05/21/2023]
Abstract
The growth properties of individual cells within a tissue determine plant morphology, and the organization of the cytoskeleton, particularly the microtubule arrays, determines cellular growth properties. We investigated the mechanisms governing the formation of transverse microtubule array patterns in axially growing Arabidopsis (Arabidopsis thaliana) epidermal hypocotyl cells. Using quantitative imaging approaches, we mapped the transition of the cortical microtubule arrays into a transverse coaligned pattern after induction with auxin and gibberellic acid. Hormone induction led to an early loss of microtubule plus end density and a rotation toward oblique patterns. Beginning 30 min after induction, transverse microtubules appeared at the cell's midzone concurrently with the loss of longitudinal polymers, eventually progressing apically and basally to remodel the array pattern. Based on the timing and known hormone-signaling pathways, we tested the hypothesis that the later events require de novo gene expression and, thus, constitute a level of genetic control over transverse patterning. We found that the presence of the translation inhibitor cycloheximide (CHX) resulted in a selective and reversible loss of transverse patterns that were replaced with radial-like pinwheel arrays exhibiting a split bipolar architecture centered at the cell's midzone. Experiments using hormone induction and CHX revealed that pinwheel arrays occur when transverse microtubules increase at the midzone but longitudinal microtubules in the split bipolar architecture are not suppressed. We propose that a key regulatory mechanism for creating the transverse microtubule coalignment in axially growing hypocotyls involves the expression of a CHX-sensitive factor that acts to suppress the nucleation of the longitudinally oriented polymers.
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Affiliation(s)
- Andrew Elliott
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405
| | - Sidney L Shaw
- Department of Biology, Indiana University, Bloomington, Indiana 47405
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11
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Oda Y. Emerging roles of cortical microtubule-membrane interactions. JOURNAL OF PLANT RESEARCH 2018; 131:5-14. [PMID: 29170834 DOI: 10.1007/s10265-017-0995-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 10/25/2017] [Indexed: 05/04/2023]
Abstract
Plant cortical microtubules have crucial roles in cell wall development. Cortical microtubules are tightly anchored to the plasma membrane in a highly ordered array, which directs the deposition of cellulose microfibrils by guiding the movement of the cellulose synthase complex. Cortical microtubules also interact with several endomembrane systems to regulate cell wall development and other cellular events. Recent studies have identified new factors that mediate interactions between cortical microtubules and endomembrane systems including the plasma membrane, endosome, exocytic vesicles, and endoplasmic reticulum. These studies revealed that cortical microtubule-membrane interactions are highly dynamic, with specialized roles in developmental and environmental signaling pathways. A recent reconstructive study identified a novel function of the cortical microtubule-plasma membrane interaction, which acts as a lateral fence that defines plasma membrane domains. This review summarizes recent advances in our understanding of the mechanisms and functions of cortical microtubule-membrane interactions.
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Affiliation(s)
- Yoshihisa Oda
- Center for Frontier Research, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka, 411-8540, Japan.
- Department of Genetics, SOKENDAI (The Graduate University for Advanced Studies), 1111 Yata, Mishima, Shizuoka, 411-8540, Japan.
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12
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Elliott A, Shaw SL. Microtubule Array Patterns Have a Common Underlying Architecture in Hypocotyl Cells. PLANT PHYSIOLOGY 2018; 176:307-325. [PMID: 28894021 PMCID: PMC5761787 DOI: 10.1104/pp.17.01112] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Accepted: 09/07/2017] [Indexed: 05/08/2023]
Abstract
Microtubules at the plant cell cortex influence cell shape by patterning the deposition of cell wall materials. The elongated cells of the hypocotyl create a variety of microtubule array patterns with differing degrees of polymer coalignment and orientation to the cell's growth axis. To gain insight into the mechanisms driving array organization, we investigated the underlying microtubule array architecture in light-grown epidermal cells with explicit reference to array pattern. We discovered that all nontransverse patterns share a common underlying array architecture, having a core unimodal peak of coaligned microtubules in a split bipolarized arrangement. The growing microtubule plus ends extend toward the cell's apex and base with a region of antiparallel microtubule overlap at the cell's midzone. This core coalignment continuously shifts between ±30° from the cell's longitudinal growth axis, forming a continuum of longitudinal and oblique arrays. Transverse arrays exhibit the same unimodal core coalignment but form local domains of microtubules polymerizing in the same direction rather than a split bipolarized architecture. Quantitative imaging experiments and analysis of katanin mutants showed that the longitudinal arrays are created from microtubules originating on the outer periclinal cell face, pointing to a cell-directed, rather than self-organizing, mechanism for specifying the major array pattern classes in the hypocotyl cell.
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Affiliation(s)
- Andrew Elliott
- Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405
| | - Sidney L Shaw
- Department of Biology, Indiana University, Bloomington, Indiana 47405
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13
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Kimura S, Kodama Y. Actin-dependence of the chloroplast cold positioning response in the liverwort Marchantia polymorpha L. PeerJ 2016; 4:e2513. [PMID: 27703856 PMCID: PMC5045877 DOI: 10.7717/peerj.2513] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Accepted: 09/01/2016] [Indexed: 12/22/2022] Open
Abstract
The subcellular positioning of chloroplasts can be changed by alterations in the environment such as light and temperature. For example, in leaf mesophyll cells, chloroplasts localize along anticlinal cell walls under high-intensity light, and along periclinal cell walls under low-intensity light. These types of positioning responses are involved in photosynthetic optimization. In light-mediated chloroplast positioning responses, chloroplasts move to the appropriate positions in an actin-dependent manner, although some exceptions also depend on microtubule. Even under low-intensity light, at low temperature (e.g., 5°C), chloroplasts localize along anticlinal cell walls; this phenomenon is termed chloroplast cold positioning. In this study, we analyzed whether chloroplast cold positioning is dependent on actin filaments and/or microtubules in the liverwort Marchantia polymorpha L. When liverwort cells were treated with drugs for the de-polymerization of actin filaments, chloroplast cold positioning was completely inhibited. In contrast, chloroplast cold positioning was not affected by treatment with a drug for the de-polymerization of microtubules. These observations indicate the actin-dependence of chloroplast cold positioning in M. polymorpha. Actin filaments during the chloroplast cold positioning response were visualized by using fluorescent probes based on fluorescent proteins in living liverwort cells, and thus, their behavior during the chloroplast cold positioning response was documented.
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Affiliation(s)
- Shun Kimura
- Center for Bioscience Research and Education, Utsunomiya University , Utsunomiya , Tochigi , Japan
| | - Yutaka Kodama
- Center for Bioscience Research and Education, Utsunomiya University , Utsunomiya , Tochigi , Japan
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14
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Takeuchi M, Karahara I, Kajimura N, Takaoka A, Murata K, Misaki K, Yonemura S, Staehelin LA, Mineyuki Y. Single microfilaments mediate the early steps of microtubule bundling during preprophase band formation in onion cotyledon epidermal cells. Mol Biol Cell 2016; 27:1809-20. [PMID: 27053663 PMCID: PMC4884071 DOI: 10.1091/mbc.e15-12-0820] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 03/30/2016] [Indexed: 12/11/2022] Open
Abstract
The preprophase band (PPB) is a cytokinetic apparatus that determines the site of cell division in plants. It originates as a broad band of microtubules (MTs) in G2 and narrows to demarcate the future division site during late prophase. Studies with fluorescent probes have shown that PPBs contain F-actin during early stages of their development but become actin depleted in late prophase. Although this suggests that actins contribute to the early stages of PPB formation, how actins contribute to PPB-MT organization remains unsolved. To address this question, we used electron tomography to investigate the spatial relationship between microfilaments (MFs) and MTs at different stages of PPB assembly in onion cotyledon epidermal cells. We demonstrate that the PPB actins observed by fluorescence microscopy correspond to short, single MFs. A majority of the MFs are bound to MTs, with a subset forming MT-MF-MT bridging structures. During the later stages of PPB assembly, the MF-mediated links between MTs are displaced by MT-MT linkers as the PPB MT arrays mature into tightly packed MT bundles. On the basis of these observations, we propose that the primary function of actins during PPB formation is to mediate the initial bundling of the PPB MTs.
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Affiliation(s)
- Miyuki Takeuchi
- Graduate School of Life Science, University of Hyogo, Himeji 671-2201, Japan Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan
| | - Ichirou Karahara
- Graduate School of Science and Engineering, University of Toyama, Toyama 930-8555, Japan
| | - Naoko Kajimura
- Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Ibaraki 567-0047, Japan
| | - Akio Takaoka
- Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Ibaraki 567-0047, Japan
| | - Kazuyoshi Murata
- National Institute for Physiological Sciences, Okazaki 444-8585, Japan
| | - Kazuyo Misaki
- RIKEN Center for Life Science Technologies, Kobe 650-0047, Japan
| | | | - L Andrew Staehelin
- Molecular, Cellular and Developmental Biology, University of Colorado, Boulder, CO 80309-0347
| | - Yoshinobu Mineyuki
- Graduate School of Life Science, University of Hyogo, Himeji 671-2201, Japan
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15
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Mace A, Wang W. Modelling the role of catastrophe, crossover and katanin‐mediated severing in the self‐organisation of plant cortical microtubules. IET Syst Biol 2015; 9:277-84. [DOI: 10.1049/iet-syb.2015.0022] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Alex Mace
- School of Computing SciencesUniversity of East AngliaNorwichNorfolkNR4 7TJUK
| | - Wenjia Wang
- School of Computing SciencesUniversity of East AngliaNorwichNorfolkNR4 7TJUK
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16
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Rodríguez VM, Soengas P, Alonso-Villaverde V, Sotelo T, Cartea ME, Velasco P. Effect of temperature stress on the early vegetative development of Brassica oleracea L. BMC PLANT BIOLOGY 2015; 15:145. [PMID: 26077340 PMCID: PMC4467057 DOI: 10.1186/s12870-015-0535-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Accepted: 05/28/2015] [Indexed: 05/04/2023]
Abstract
BACKGROUND Due to its biennual life cycle Brassica oleracea is especially exposed to seasonal changes in temperature that could limit its growth and fitness. Thermal stress could limit plant growth, leaf development and photosynthesis. We evaluated the performance of two local populations of B. oleracea: one population of cabbage (B. oleracea capitata group) and one population of kale (B. oleracea acephala group) under limiting low and high temperatures. RESULTS There were differences between crops and how they responded to high and low temperature stress. Low temperatures especially affect photosynthesis and fresh weight. Stomatal conductance and the leaf water content were dramatically reduced and plants produce smaller and thicker leaves. Under high temperatures there was a reduction of the weight that could be associated to a general impairment of the photosynthetic activity. CONCLUSIONS Although high temperatures significantly reduced the dry weight of seedlings, in general terms, low temperature had a higher impact in B. oleracea physiology than high temperature. Interestingly, our results suggest that the capitata population is less sensitive to changes in air temperature than the acephala population.
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Affiliation(s)
- Víctor M Rodríguez
- Group of Genetics, Breeding and Biochemistry of Brassicas. Misión Biológica de Galicia (MBG-CSIC), Apartado 28, 36080, Pontevedra, Spain.
| | - Pilar Soengas
- Group of Genetics, Breeding and Biochemistry of Brassicas. Misión Biológica de Galicia (MBG-CSIC), Apartado 28, 36080, Pontevedra, Spain.
| | | | - Tamara Sotelo
- Group of Genetics, Breeding and Biochemistry of Brassicas. Misión Biológica de Galicia (MBG-CSIC), Apartado 28, 36080, Pontevedra, Spain.
| | - María E Cartea
- Group of Genetics, Breeding and Biochemistry of Brassicas. Misión Biológica de Galicia (MBG-CSIC), Apartado 28, 36080, Pontevedra, Spain.
| | - Pablo Velasco
- Group of Genetics, Breeding and Biochemistry of Brassicas. Misión Biológica de Galicia (MBG-CSIC), Apartado 28, 36080, Pontevedra, Spain.
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17
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Eren EC, Dixit R, Gautam N. Stochastic models for plant microtubule self-organization and structure. J Math Biol 2015; 71:1353-85. [PMID: 25700800 DOI: 10.1007/s00285-015-0860-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 01/04/2015] [Indexed: 11/29/2022]
Abstract
One of the key enablers of shape and growth in plant cells is the cortical microtubule (CMT) system, which is a polymer array that forms an appropriately-structured scaffolding in each cell. Plant biologists have shown that stochastic dynamics and simple rules of interactions between CMTs can lead to a coaligned CMT array structure. However, the mechanisms and conditions that cause CMT arrays to become organized are not well understood. It is prohibitively time-consuming to use actual plants to study the effect of various genetic mutations and environmental conditions on CMT self-organization. In fact, even computer simulations with multiple replications are not fast enough due to the spatio-temporal complexity of the system. To redress this shortcoming, we develop analytical models and methods for expeditiously computing CMT system metrics that are related to self-organization and array structure. In particular, we formulate a mean-field model to derive sufficient conditions for the organization to occur. We show that growth-prone dynamics itself is sufficient to lead to organization in presence of interactions in the system. In addition, for such systems, we develop predictive methods for estimation of system metrics such as expected average length and number of CMTs over time, using a stochastic fluid-flow model, transient analysis, and approximation algorithms tailored to our problem. We illustrate the effectiveness of our approach through numerical test instances and discuss biological insights.
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Affiliation(s)
- Ezgi C Eren
- PROS, Inc, 3100 Main Street, Suite #900, Houston, TX, 77002, USA.
| | - Ram Dixit
- Department of Biology, Washington University in St. Louis, Campus Box 1137, St. Louis, MO, 63130-1137, USA.
| | - Natarajan Gautam
- Department of Industrial and Systems Engineering, Texas A&M University, Mailstop 3131, College Station, TX, 77843-3131, USA.
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18
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Mazars C, Brière C, Grat S, Pichereaux C, Rossignol M, Pereda-Loth V, Eche B, Boucheron-Dubuisson E, Le Disquet I, Medina FJ, Graziana A, Carnero-Diaz E. Microgravity induces changes in microsome-associated proteins of Arabidopsis seedlings grown on board the international space station. PLoS One 2014; 9:e91814. [PMID: 24618597 PMCID: PMC3950288 DOI: 10.1371/journal.pone.0091814] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Accepted: 02/14/2014] [Indexed: 11/18/2022] Open
Abstract
The "GENARA A" experiment was designed to monitor global changes in the proteome of membranes of Arabidopsis thaliana seedlings subjected to microgravity on board the International Space Station (ISS). For this purpose, 12-day-old seedlings were grown either in space, in the European Modular Cultivation System (EMCS) under microgravity or on a 1 g centrifuge, or on the ground. Proteins associated to membranes were selectively extracted from microsomes and identified and quantified through LC-MS-MS using a label-free method. Among the 1484 proteins identified and quantified in the 3 conditions mentioned above, 80 membrane-associated proteins were significantly more abundant in seedlings grown under microgravity in space than under 1 g (space and ground) and 69 were less abundant. Clustering of these proteins according to their predicted function indicates that proteins associated to auxin metabolism and trafficking were depleted in the microsomal fraction in µg space conditions, whereas proteins associated to stress responses, defence and metabolism were more abundant in µg than in 1 g indicating that microgravity is perceived by plants as a stressful environment. These results clearly indicate that a global membrane proteomics approach gives a snapshot of the cell status and its signaling activity in response to microgravity and highlight the major processes affected.
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Affiliation(s)
- Christian Mazars
- Laboratoire de Recherches en Sciences Végétales, Université de Toulouse UPS, CNRS UMR5546, Castanet-Tolosan, France
- * E-mail:
| | - Christian Brière
- Laboratoire de Recherches en Sciences Végétales, Université de Toulouse UPS, CNRS UMR5546, Castanet-Tolosan, France
| | - Sabine Grat
- Laboratoire de Recherches en Sciences Végétales, Université de Toulouse UPS, CNRS UMR5546, Castanet-Tolosan, France
| | - Carole Pichereaux
- Institut de Pharmacologie et de Biologie Structurale IPBS CNRS, Fédération de Recherche 3450 Agrobiosciences Interactions et Biodiversités Plateforme Protéomique Génopole Toulouse Midi Pyrénées, Toulouse, France
| | - Michel Rossignol
- Institut de Pharmacologie et de Biologie Structurale IPBS CNRS, Fédération de Recherche 3450 Agrobiosciences Interactions et Biodiversités Plateforme Protéomique Génopole Toulouse Midi Pyrénées, Toulouse, France
| | | | | | | | - Isabel Le Disquet
- UR5-PCMP-EAC 7180 CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Paris, France
| | | | - Annick Graziana
- Laboratoire de Recherches en Sciences Végétales, Université de Toulouse UPS, CNRS UMR5546, Castanet-Tolosan, France
| | - Eugénie Carnero-Diaz
- UR5-PCMP-EAC 7180 CNRS, Université Pierre et Marie Curie-Sorbonne Universités, Paris, France
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19
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Struk S, Dhonukshe P. MAPs: cellular navigators for microtubule array orientations in Arabidopsis. PLANT CELL REPORTS 2014; 33:1-21. [PMID: 23903948 DOI: 10.1007/s00299-013-1486-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Revised: 07/14/2013] [Accepted: 07/18/2013] [Indexed: 05/24/2023]
Abstract
Microtubules are subcellular nanotubes composed of α- and β-tubulin that arise from microtubule nucleation sites, mainly composed of γ-tubulin complexes [corrected]. Cell wall encased plant cells have evolved four distinct microtubule arrays that regulate cell division and expansion. Microtubule-associated proteins, the so called MAPs, construct, destruct and reorganize microtubule arrays thus regulating their spatiotemporal transitions during the cell cycle. By physically binding to microtubules and/or modulating their functions, MAPs control microtubule dynamic instability and/or interfilament cross talk. We survey the recent analyses of Arabidopsis MAPs such as MAP65, MOR1, CLASP, katanin, TON1, FASS, TRM, TAN1 and kinesins in terms of their effects on microtubule array organizations and plant development.
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Affiliation(s)
- Sylwia Struk
- Department of Plant Systems Biology, VIB, 9052, Ghent, Belgium
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20
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Oda Y, Fukuda H. The dynamic interplay of plasma membrane domains and cortical microtubules in secondary cell wall patterning. FRONTIERS IN PLANT SCIENCE 2013; 4:511. [PMID: 24381577 PMCID: PMC3865431 DOI: 10.3389/fpls.2013.00511] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Accepted: 11/28/2013] [Indexed: 05/21/2023]
Abstract
Patterning of the cellulosic cell wall underlies the shape and function of plant cells. The cortical microtubule array plays a central role in the regulation of cell wall patterns. However, the regulatory mechanisms by which secondary cell wall patterns are established through cortical microtubules remain to be fully determined. Our recent study in xylem vessel cells revealed that a mutual inhibitory interaction between cortical microtubules and distinct plasma membrane domains leads to distinctive patterning in secondary cell walls. Our research revealed that the recycling of active and inactive ROP proteins by a specific GAP and GEF pair establishes distinct de novo plasma membrane domains. Active ROP recruits a plant-specific microtubule-associated protein, MIDD1, which mediates the mutual interaction between cortical microtubules and plasma membrane domains. In this mini review, we summarize recent research regarding secondary wall patterning, with a focus on the emerging interplay between plasma membrane domains and cortical microtubules through MIDD1 and ROP.
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Affiliation(s)
- Yoshihisa Oda
- Department of Biological Sciences, Graduate School of Science, The University of TokyoTokyo, Japan
- Precursory Research for Embryonic Science and Technology, Japan Science and Technology AgencySaitama, Japan
| | - Hiroo Fukuda
- Department of Biological Sciences, Graduate School of Science, The University of TokyoTokyo, Japan
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21
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Hepler PK, Pickett-Heaps JD, Gunning BES. Some retrospectives on early studies of plant microtubules. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2013; 75:189-201. [PMID: 23496242 DOI: 10.1111/tpj.12176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 02/20/2013] [Accepted: 03/12/2013] [Indexed: 06/01/2023]
Abstract
We pay tribute to the seminal paper 'A microtubule in plant cell fine structure' by Myron C. Ledbetter and Keith R. Porter (1963) by summarizing the very limited knowledge of plant cell ultrastructure that we had prior to that publication, and, by way of our three retrospective accounts, show how this paper stimulated and influenced subsequent research on plant microtubules. Micrographs of historical interest are presented that are either previously unpublished or from primary publications.
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Affiliation(s)
- Peter K Hepler
- Biology Department, University of Massachusetts, Amherst, MA 00103, USA
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22
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Liu C, Qi X, Zhao Q, Yu J. Characterization and functional analysis of the potato pollen-specific microtubule-associated protein SBgLR in tobacco. PLoS One 2013; 8:e60543. [PMID: 23536914 PMCID: PMC3607588 DOI: 10.1371/journal.pone.0060543] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 02/26/2013] [Indexed: 01/16/2023] Open
Abstract
Microtubule-associated proteins play a crucial role in the regulation of microtubule dynamics, and are very important for plant cell and organ development. SBgLR is a potato pollen-specific protein, with five imperfect V-V-E-K-K-N/E-E repetitive motifs that are responsible for microtubule binding activity. In present study, SBgLR showed typical microtubule-associated protein characteristics; it bound tubulin and microtubules, and colocalized with microtubules in vitro. We also found that SBgLR could form oligomers, and that both the SBgLR monomers and oligomers bundle microtubules in vitro. Constitutive expression of SBgLR in tobacco caused curving and right-handed twisting root growth, abnormal directional cell expansion and cell layer arrangement, and pollen abortion. Immunofluorescence staining assays revealed that microtubule organization is altered in root epidermal cells in SBgLR-overexpressing lines. These suggest that SBgLR functions as a microtubule-associated protein in pollen development. Our results indicate that normal organization of MTs may be crucial for pollen development.
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Affiliation(s)
- Chen Liu
- State Key Laboratory for Agro-biotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Xin Qi
- State Key Laboratory for Agro-biotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Qian Zhao
- State Key Laboratory for Agro-biotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
| | - Jingjuan Yu
- State Key Laboratory for Agro-biotechnology, College of Biological Sciences, China Agricultural University, Beijing, China
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23
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Lindeboom JJ, Lioutas A, Deinum EE, Tindemans SH, Ehrhardt DW, Emons AMC, Vos JW, Mulder BM. Cortical microtubule arrays are initiated from a nonrandom prepattern driven by atypical microtubule initiation. PLANT PHYSIOLOGY 2013; 161:1189-201. [PMID: 23300168 PMCID: PMC3585589 DOI: 10.1104/pp.112.204057] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Accepted: 01/04/2013] [Indexed: 05/23/2023]
Abstract
The ordered arrangement of cortical microtubules in growing plant cells is essential for anisotropic cell expansion and, hence, for plant morphogenesis. These arrays are dismantled when the microtubule cytoskeleton is rearranged during mitosis and reassembled following completion of cytokinesis. The reassembly of the cortical array has often been considered as initiating from a state of randomness, from which order arises at least partly through self-organizing mechanisms. However, some studies have shown evidence for ordering at early stages of array assembly. To investigate how cortical arrays are initiated in higher plant cells, we performed live-cell imaging studies of cortical array assembly in tobacco (Nicotiana tabacum) Bright Yellow-2 cells after cytokinesis and drug-induced disassembly. We found that cortical arrays in both cases did not initiate randomly but with a significant overrepresentation of microtubules at diagonal angles with respect to the cell axis, which coincides with the predominant orientation of the microtubules before their disappearance from the cell cortex in preprophase. In Arabidopsis (Arabidopsis thaliana) root cells, recovery from drug-induced disassembly was also nonrandom and correlated with the organization of the previous array, although no diagonal bias was observed in these cells. Surprisingly, during initiation, only about one-half of the new microtubules were nucleated from locations marked by green fluorescent protein-γ-tubulin complex protein2-tagged γ-nucleation complexes (γ-tubulin ring complex), therefore indicating that a large proportion of early polymers was initiated by a noncanonical mechanism not involving γ-tubulin ring complex. Simulation studies indicate that the high rate of noncanonical initiation of new microtubules has the potential to accelerate the rate of array repopulation.
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Affiliation(s)
- Jelmer J Lindeboom
- Laboratory of Cell Biology, Wageningen University, 6708 PB Wageningen, The Netherlands.
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24
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Stoppin-Mellet V, Fache V, Portran D, Martiel JL, Vantard M. MAP65 coordinate microtubule growth during bundle formation. PLoS One 2013; 8:e56808. [PMID: 23437247 PMCID: PMC3578873 DOI: 10.1371/journal.pone.0056808] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Accepted: 01/15/2013] [Indexed: 12/27/2022] Open
Abstract
Microtubules (MTs) are highly dynamical structures that play a crucial role in cell physiology. In cooperation with microtubule-associated proteins (MAPs), MTs form bundles endowing cells with specific mechanisms to control their shape or generate forces. Whether the dynamics of MTs is affected by the lateral connections that MAPs make between MTs during bundle formation is still under debate. Using in vitro reconstitution of MT bundling, we analyzed the dynamics of MT bundles generated by two plant MAP65 (MAP65-1/4), MAP65-1 being the plant ortholog of vertebrate PRC1 and yeast Ase1. MAP65-1/4 limit the amplitude of MT bundle depolymerization and increase the elongation phases. The subsequent sustained elongation of bundles is governed by the coordination of MT growth, so that MT ends come in close vicinity. We develop a model based on the assumption that both MAP65-1/4 block MT depolymerization. Model simulations reveal that rescue frequencies are higher between parallel than between anti-parallel MTs. In consequence the polarity of bundled MTs by MAP65 controls the amplitude of bundle's growth. Our results illustrate how MAP-induced MT-bundling, which is finely tuned by MT polarity, robustly coordinates MT elongation within bundles.
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Affiliation(s)
- Virginie Stoppin-Mellet
- Laboratoaire de Physiologie Cellulaire & Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), Centre National de la Recherche Scientifique/Commissariat à l’énergie atomique et aux énergies alternatives/Institut National de la Recherche Agronomique/Université Joseph Fourier (CNRS/CEA/INRA/UJF), Grenoble, France
- * E-mail: (VSM) (VS); (MV) (MV)
| | - Vincent Fache
- Laboratoaire de Physiologie Cellulaire & Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), Centre National de la Recherche Scientifique/Commissariat à l’énergie atomique et aux énergies alternatives/Institut National de la Recherche Agronomique/Université Joseph Fourier (CNRS/CEA/INRA/UJF), Grenoble, France
| | - Didier Portran
- Laboratoaire de Physiologie Cellulaire & Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), Centre National de la Recherche Scientifique/Commissariat à l’énergie atomique et aux énergies alternatives/Institut National de la Recherche Agronomique/Université Joseph Fourier (CNRS/CEA/INRA/UJF), Grenoble, France
| | - Jean-Louis Martiel
- Laboratoaire de Physiologie Cellulaire & Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), Centre National de la Recherche Scientifique/Commissariat à l’énergie atomique et aux énergies alternatives/Institut National de la Recherche Agronomique/Université Joseph Fourier (CNRS/CEA/INRA/UJF), Grenoble, France
| | - Marylin Vantard
- Laboratoaire de Physiologie Cellulaire & Végétale, Institut de Recherches en Technologies et Sciences pour le Vivant (iRTSV), Centre National de la Recherche Scientifique/Commissariat à l’énergie atomique et aux énergies alternatives/Institut National de la Recherche Agronomique/Université Joseph Fourier (CNRS/CEA/INRA/UJF), Grenoble, France
- * E-mail: (VSM) (VS); (MV) (MV)
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25
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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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26
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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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27
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Di Sole F, Vadnagara K, Moe OW, Babich V. Calcineurin homologous protein: a multifunctional Ca2+-binding protein family. Am J Physiol Renal Physiol 2012; 303:F165-79. [PMID: 22189947 PMCID: PMC3404583 DOI: 10.1152/ajprenal.00628.2011] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2012] [Accepted: 05/17/2012] [Indexed: 12/13/2022] Open
Abstract
The calcineurin homologous protein (CHP) belongs to an evolutionarily conserved Ca(2+)-binding protein subfamily. The CHP subfamily is composed of CHP1, CHP2, and CHP3, which in vertebrates share significant homology at the protein level with each other and between other Ca(2+)-binding proteins. The CHP structure consists of two globular domains containing from one to four EF-hand structural motifs (calcium-binding regions composed of two helixes, E and F, joined by a loop), the myristoylation, and nuclear export signals. These structural features are essential for the function of the three members of the CHP subfamily. Indeed, CHP1-CHP3 have multiple and diverse essential functions, ranging from the regulation of the plasma membrane Na(+)/H(+) exchanger protein function, to carrier vesicle trafficking and gene transcription. The diverse functions attributed to the CHP subfamily rendered an understanding of its action highly complex and often controversial. This review provides a comprehensive and organized examination of the properties and physiological roles of the CHP subfamily with a view to revealing a link between CHP diverse functions.
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Affiliation(s)
- Francesca Di Sole
- Department of Internal Medicine, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd., Dallas, TX 75390-8885, USA.
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28
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Tulin A, McClerklin S, Huang Y, Dixit R. Single-molecule analysis of the microtubule cross-linking protein MAP65-1 reveals a molecular mechanism for contact-angle-dependent microtubule bundling. Biophys J 2012; 102:802-9. [PMID: 22385851 DOI: 10.1016/j.bpj.2012.01.008] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2011] [Revised: 01/04/2012] [Accepted: 01/09/2012] [Indexed: 11/29/2022] Open
Abstract
Bundling of microtubules (MTs) is critical for the formation of complex MT arrays. In land plants, the interphase cortical MTs form bundles specifically following shallow-angle encounters between them. To investigate how cells select particular MT contact angles for bundling, we used an in vitro reconstitution approach consisting of dynamic MTs and the MT-cross-linking protein MAP65-1. We found that MAP65-1 binds to MTs as monomers and inherently targets antiparallel MTs for bundling. Dwell-time analysis showed that the affinity of MAP65-1 for antiparallel overlapping MTs is about three times higher than its affinity for single MTs and parallel overlapping MTs. We also found that purified MAP65-1 exclusively selects shallow-angle MT encounters for bundling, indicating that this activity is an intrinsic property of MAP65-1. Reconstitution experiments with mutant MAP65-1 proteins with different numbers of spectrin repeats within the N-terminal rod domain showed that the length of the rod domain is a major determinant of the range of MT bundling angles. The length of the rod domain also determined the distance between MTs within a bundle. Together, our data show that the rod domain of MAP65-1 acts both as a spacer and as a structural element that specifies the MT encounter angles that are conducive for bundling.
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Affiliation(s)
- Amanda Tulin
- Biology Department, Washington University in St. Louis, St. Louis, Missouri, USA
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29
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Eren EC, Gautam N, Dixit R. Computer simulation and mathematical models of the noncentrosomal plant cortical microtubule cytoskeleton. Cytoskeleton (Hoboken) 2012; 69:144-54. [PMID: 22266809 DOI: 10.1002/cm.21009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Revised: 01/17/2012] [Accepted: 01/18/2012] [Indexed: 11/11/2022]
Abstract
There is rising interest in modeling the noncentrosomal cortical microtubule cytoskeleton of plant cells, particularly its organization into ordered arrays and the mechanisms that facilitate this organization. In this review, we discuss quantitative models of this highly complex and dynamic structure both at a cellular and molecular level. We report differences in methodologies and assumptions of different models as well as their controversial results. Our review provides insights for future studies to resolve these controversies, in addition to underlining the common results between various models. We also highlight the need to compare the results from simulation and mathematical models with quantitative data from biological experiments in order to test the validity of the models and to further improve them. It is our hope that this review will serve to provide guidelines for how to combine quantitative and experimental techniques to develop higher-level models of the plant cytoskeleton in the future.
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Affiliation(s)
- Ezgi Can Eren
- Department of Industrial and Systems Engineering, Texas A&M University, College Station, Texas, USA
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30
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Fujita M, Lechner B, Barton DA, Overall RL, Wasteneys GO. The missing link: do cortical microtubules define plasma membrane nanodomains that modulate cellulose biosynthesis? PROTOPLASMA 2012; 249 Suppl 1:S59-67. [PMID: 22057629 DOI: 10.1007/s00709-011-0332-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 10/04/2011] [Indexed: 05/08/2023]
Abstract
Cellulose production is a crucial aspect of plant growth and development. It is functionally linked to cortical microtubules, which self-organize into highly ordered arrays often situated in close proximity to plasma membrane-bound cellulose synthase complexes (CSCs). Although most models put forward to explain the microtubule-cellulose relationship have considered mechanisms by which cortical microtubule arrays influence the orientation of cellulose microfibrils, little attention has been paid to how microtubules affect the physicochemical properties of cellulose. A recent study using the model system Arabidopsis, however, indicates that microtubules can modulate the crystalline and amorphous content of cellulose microfibrils. Microtubules are required during rapid growth for reducing crystalline content, which is predicted to increase the degree to which cellulose is tethered by hemicellulosic polysaccharides. Such tethering is, in turn, critical for maintaining unidirectional cell expansion. In this article, we hypothesize that cortical microtubules influence the crystalline content of cellulose either by controlling plasma membrane fluidity or by modulating the deposition of noncellulosic wall components in the vicinity of the CSCs. We discuss the current limitations of imaging technology to address these hypotheses and identify the image acquisition and processing strategies that will integrate live imaging with super resolution three-dimensional information.
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Affiliation(s)
- Miki Fujita
- Department of Botany, The University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
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31
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CHAN J. Microtubule and cellulose microfibril orientation during plant cell and organ growth. J Microsc 2011; 247:23-32. [DOI: 10.1111/j.1365-2818.2011.03585.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
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32
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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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Lucas JR, Courtney S, Hassfurder M, Dhingra S, Bryant A, Shaw SL. Microtubule-associated proteins MAP65-1 and MAP65-2 positively regulate axial cell growth in etiolated Arabidopsis hypocotyls. THE PLANT CELL 2011; 23:1889-903. [PMID: 21551389 PMCID: PMC3123956 DOI: 10.1105/tpc.111.084970] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2011] [Revised: 04/05/2011] [Accepted: 04/18/2011] [Indexed: 05/18/2023]
Abstract
The Arabidopsis thaliana MAP65-1 and MAP65-2 genes are members of the larger eukaryotic MAP65/ASE1/PRC gene family of microtubule-associated proteins. We created fluorescent protein fusions driven by native promoters that colocalized MAP65-1 and MAP65-2 to a subset of interphase microtubule bundles in all epidermal hypocotyl cells. MAP65-1 and MAP65-2 labeling was highly dynamic within microtubule bundles, showing episodes of linear extension and retraction coincident with microtubule growth and shortening. Dynamic colocalization of MAP65-1/2 with polymerizing microtubules provides in vivo evidence that plant cortical microtubules bundle through a microtubule-microtubule templating mechanism. Analysis of etiolated hypocotyl length in map65-1 and map65-2 mutants revealed a critical role for MAP65-2 in modulating axial cell growth. Double map65-1 map65-2 mutants showed significant growth retardation with no obvious cell swelling, twisting, or morphological defects. Surprisingly, interphase microtubules formed coaligned arrays transverse to the plant growth axis in dark-grown and GA(4)-treated light-grown map65-1 map65-2 mutant plants. We conclude that MAP65-1 and MAP65-2 play a critical role in the microtubule-dependent mechanism for specifying axial cell growth in the expanding hypocotyl, independent of any mechanical role in microtubule array organization.
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Intracellular Movements: Integration at the Cellular Level as Reflected in the Organization of Organelle Movements. MECHANICAL INTEGRATION OF PLANT CELLS AND PLANTS 2011. [DOI: 10.1007/978-3-642-19091-9_4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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35
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Ruelland E, Zachowski A. How plants sense temperature. ENVIRONMENTAL AND EXPERIMENTAL BOTANY 2010. [PMID: 0 DOI: 10.1016/j.envexpbot.2010.05.011] [Citation(s) in RCA: 164] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
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36
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Shaw SL, Lucas J. Intrabundle microtubule dynamics in the Arabidopsis cortical array. Cytoskeleton (Hoboken) 2010; 68:56-67. [PMID: 20960529 DOI: 10.1002/cm.20495] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 09/09/2010] [Accepted: 10/07/2010] [Indexed: 11/06/2022]
Abstract
We tested the general hypothesis that bundling stabilizes the dynamic properties of the constituent microtubules (MTs) in vivo. We quantified the assembly dynamics of bundled and unbundled MTs in the interphase cortical array of Arabidopsis hypocotyl cells using high dynamic range spinning disk confocal microscopy. We find no evidence that bundled MTs are stabilized against depolymerization through changes to their dynamic properties. Our observations of MT plus and minus ends indicate that both bundled and unbundled polymers undergo persistent treadmilling in this system. We conclude that the temporal persistence of MT subassemblies in the Arabidopsis cortical array is largely dependent upon recruitment or nucleation of new treadmilling MTs and not on polymer stabilization. Monte Carlo simulations suggest that small differences discovered in the dynamic properties between bundled and unbundled polymers would produce relatively small macroscopic effects on the larger MT array.
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Affiliation(s)
- Sidney L Shaw
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA.
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37
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Hawkins RJ, Tindemans SH, Mulder BM. Model for the orientational ordering of the plant microtubule cortical array. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 82:011911. [PMID: 20866652 DOI: 10.1103/physreve.82.011911] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Indexed: 05/13/2023]
Abstract
The plant microtubule cortical array is a striking feature of all growing plant cells. It consists of a more or less homogeneously distributed array of highly aligned microtubules connected to the inner side of the plasma membrane and oriented transversely to the cell growth axis. Here, we formulate a continuum model to describe the origin of orientational order in such confined arrays of dynamical microtubules. The model is based on recent experimental observations that show that a growing cortical microtubule can interact through angle dependent collisions with pre-existing microtubules that can lead either to co-alignment of the growth, retraction through catastrophe induction or crossing over the encountered microtubule. We identify a single control parameter, which is fully determined by the nucleation rate and intrinsic dynamics of individual microtubules. We solve the model analytically in the stationary isotropic phase, discuss the limits of stability of this isotropic phase, and explicitly solve for the ordered stationary states in a simplified version of the model.
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Affiliation(s)
- Rhoda J Hawkins
- FOM Institute AMOLF, Science Park 104, 1098 XG Amsterdam, The Netherlands.
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38
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Eren EC, Dixit R, Gautam N. A three-dimensional computer simulation model reveals the mechanisms for self-organization of plant cortical microtubules into oblique arrays. Mol Biol Cell 2010; 21:2674-84. [PMID: 20519434 PMCID: PMC2912353 DOI: 10.1091/mbc.e10-02-0136] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
We use a 3D computer simulation model that is based on experimental data to understand how the noncentrosomal plant cortical microtubules self-organize into specific ordered patterns in both wild-type and mutant plants. The noncentrosomal cortical microtubules (CMTs) of plant cells self-organize into a parallel three-dimensional (3D) array that is oriented transverse to the cell elongation axis in wild-type plants and is oblique in some of the mutants that show twisted growth. To study the mechanisms of CMT array organization, we developed a 3D computer simulation model based on experimentally observed properties of CMTs. Our computer model accurately mimics transverse array organization and other fundamental properties of CMTs observed in rapidly elongating wild-type cells as well as the defective CMT phenotypes observed in the Arabidopsis mor1-1 and fra2 mutants. We found that CMT interactions, boundary conditions, and the bundling cutoff angle impact the rate and extent of CMT organization, whereas branch-form CMT nucleation did not significantly impact the rate of CMT organization but was necessary to generate polarity during CMT organization. We also found that the dynamic instability parameters from twisted growth mutants were not sufficient to generate oblique CMT arrays. Instead, we found that parameters regulating branch-form CMT nucleation and boundary conditions at the end walls are important for forming oblique CMT arrays. Together, our computer model provides new mechanistic insights into how plant CMTs self-organize into specific 3D arrangements.
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Affiliation(s)
- Ezgi Can Eren
- Department of Industrial and Systems Engineering, Texas A&M University, College Station, TX 77843, USA
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39
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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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40
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Allard JF, Wasteneys GO, Cytrynbaum EN. Mechanisms of self-organization of cortical microtubules in plants revealed by computational simulations. Mol Biol Cell 2009; 21:278-86. [PMID: 19910489 PMCID: PMC2808237 DOI: 10.1091/mbc.e09-07-0579] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Microtubules confined to the two-dimensional cortex of elongating plant cells must form a parallel yet dispersed array transverse to the elongation axis for proper cell wall expansion. Some of these microtubules exhibit free minus-ends, leading to migration at the cortex by hybrid treadmilling. Collisions between microtubules can result in plus-end entrainment ("zippering") or rapid depolymerization. Here, we present a computational model of cortical microtubule organization. We find that plus-end entrainment leads to self-organization of microtubules into parallel arrays, whereas catastrophe-inducing collisions do not. Catastrophe-inducing boundaries (e.g., upper and lower cross-walls) can tune the orientation of an ordered array to a direction transverse to elongation. We also find that changes in dynamic instability parameters, such as in mor1-1 mutants, can impede self-organization, in agreement with experimental data. Increased entrainment, as seen in clasp-1 mutants, conserves self-organization, but delays its onset and fails to demonstrate increased ordering. We find that branched nucleation at acute angles off existing microtubules results in distinctive sparse arrays and infer either that microtubule-independent or coparallel nucleation must dominate. Our simulations lead to several testable predictions, including the effects of reduced microtubule severing in katanin mutants.
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Affiliation(s)
- Jun F Allard
- Institute of Applied Mathematics and Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z2
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41
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BARTON D, GARDINER J, OVERALL R. Towards correlative imaging of plant cortical microtubule arrays: combining ultrastructure with real-time microtubule dynamics. J Microsc 2009; 235:241-51. [DOI: 10.1111/j.1365-2818.2009.03224.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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42
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Chan J, Sambade A, Calder G, Lloyd C. Arabidopsis cortical microtubules are initiated along, as well as branching from, existing microtubules. THE PLANT CELL 2009; 21:2298-306. [PMID: 19706794 PMCID: PMC2751946 DOI: 10.1105/tpc.109.069716] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2009] [Revised: 08/05/2009] [Accepted: 08/13/2009] [Indexed: 05/18/2023]
Abstract
The principles by which cortical microtubules self-organize into a global template hold important implications for cell wall patterning. Microtubules move along bundles of microtubules, and neighboring bundles tend to form mobile domains that flow in a common direction. The bundles themselves move slowly and for longer than the individual microtubules, with domains describing slow rotary patterns. Despite this tendency for colinearity, microtubules have been seen to branch off extant microtubules at approximately 45 degrees . To examine this paradoxical behavior, we investigated whether some microtubules may be born on and grow along extant microtubule(s). The plus-end markers Arabidopsis thaliana end binding protein 1a, AtEB1a-GFP, and Arabidopsis SPIRAL1, SPR1-GFP, allowed microtubules of known polarity to be distinguished from underlying microtubules. This showed that the majority of microtubules do branch but in a direction heavily biased toward the plus end of the mother microtubule: few grow backward, consistent with the common polarity of domains. However, we also found that a significant proportion of emergent comets do follow the axes of extant microtubules, both at sites of apparent microtubule nucleation and at cross-over points. These phenomena help explain the persistence of bundles and counterbalance the tendency to branch.
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Affiliation(s)
- Jordi Chan
- Department of Cell and Developmental Biology, John Ines Centre, Colney, Norwich, NR4 7UH, United Kingdom.
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43
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Abstract
Cytokinesis is the terminal step of the cell cycle during which a mother cell divides into daughter cells. Often, the machinery of cytokinesis is positioned in such a way that daughter cells are born roughly equal in size. However, in many specialized cell types or under certain environmental conditions, the cell division machinery is placed at nonmedial positions to produce daughter cells of different sizes and in many cases of different fates. Here we review the different mechanisms that position the division machinery in prokaryotic and eukaryotic cell types. We also describe cytokinesis-positioning mechanisms that are not adequately explained by studies in model organisms and model cell types.
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Affiliation(s)
- Snezhana Oliferenko
- Temasek Life Sciences Laboratory and the Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
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44
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Wolff J. Plasma membrane tubulin. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1788:1415-33. [PMID: 19328773 DOI: 10.1016/j.bbamem.2009.03.013] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Revised: 03/13/2009] [Accepted: 03/19/2009] [Indexed: 01/17/2023]
Abstract
The association of tubulin with the plasma membrane comprises multiple levels of penetration into the bilayer: from integral membrane protein, to attachment via palmitoylation, to surface binding, and to microtubules attached by linker proteins to proteins in the membrane. Here we discuss the soundness and weaknesses of the chemical and biochemical evidence marshaled to support these associations, as well as the mechanisms by which tubulin or microtubules may regulate functions at the plasma membrane.
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Affiliation(s)
- J Wolff
- Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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45
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Ho AYY, Day DA, Brown MH, Marc J. Arabidopsis phospholipase Dδ as an initiator of cytoskeleton-mediated signalling to fundamental cellular processes. FUNCTIONAL PLANT BIOLOGY : FPB 2009; 36:190-198. [PMID: 32688638 DOI: 10.1071/fp08222] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Accepted: 12/10/2008] [Indexed: 06/11/2023]
Abstract
Phospholipase D (PLD), in combination with the cytoskeleton, plays a key role in plant signal transduction. One isotype of the multigene Arabidopsis PLD family, AtPLDδ, has been implicated in binding microtubules, although the molecular details of the mechanism and identities of potential interaction partners are unclear. We constructed a GFP-AtPLDδ reporter gene, stably transformed it into an Arabidopsis suspension cell line, and used epitope-tagged affinity pull-down assays to isolate a complex of co-purifying proteins. Mass spectrometry analysis of the complex revealed a set of proteins including β-tubulin, actin 7, HSP70, clathrin heavy chain, ATP synthase subunits, and a band 7-4/flotillin homologue. Sequence alignments with defined tubulin- and actin-binding regions from human HsPLD2 revealed highly homologous regions in all 12 AtPLD isotypes, suggesting direct interactions of AtPLDδ with tubulin and actin, while interactions with the remaining partners are likely to be mediated by the cytoskeleton. We propose that AtPLDδ acts through a complex of cytoskeletal and partner proteins to modulate fundamental cellular processes such as cytoskeletal rearrangements, vesicular trafficking, assembly of Golgi apparatus, mitosis and cytokinesis.
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Affiliation(s)
- Angela Y Y Ho
- School of Biological Sciences, Macleay Building A12, University of Sydney, Sydney, NSW 2006, Australia
| | - David A Day
- School of Biological Sciences, Macleay Building A12, University of Sydney, Sydney, NSW 2006, Australia
| | - Melissa H Brown
- School of Biological Sciences, Macleay Building A12, University of Sydney, Sydney, NSW 2006, Australia
| | - Jan Marc
- School of Biological Sciences, Macleay Building A12, University of Sydney, Sydney, NSW 2006, Australia
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46
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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: 128] [Impact Index Per Article: 8.5] [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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47
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Ambrose JC, Cyr R. Mitotic spindle organization by the preprophase band. MOLECULAR PLANT 2008; 1:950-60. [PMID: 19825595 DOI: 10.1093/mp/ssn054] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
In higher plants, the preprophase band (PPB) of microtubules (MTs) forecasts the cell division site prior to mitosis and specifies the organization of MTs into a bipolar prophase spindle surrounding the nucleus. However, the mechanisms governing this PPB-dependent establishment of bipolarity are unclear. Here, we present evidence from live cell imaging studies that suggest a role for the MTs bridging the PPB and the prophase nucleus in mediating this function. Results from drug treatments, along with genetic evidence from null kinesin plants, suggest that these MTs contribute to the bipolarity, orientation, and position of the prophase spindle. Specifically, the absence of these bridge MTs is associated with lack of bipolarity, while non-uniform distributions of bridge MTs correlate with prophase spindle migration, deformation, and enhanced bipolarity toward the region of highest bridge MT density. This behavior does not require actomyosin-based forces, and is enhanced by suppressing MT dynamics with taxol. These observations occur during late prophase, and are coincident with the gradual closing of annular spindle poles. Based on these data, we describe a hypothetical mechanism for bridge MT-dependent organization of prophase spindles.
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Affiliation(s)
- J Christian Ambrose
- The Pennsylvania State University, Department of Biology, University Park, PA 16802, USA
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48
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Lindeboom J, Mulder BM, Vos JW, Ketelaar T, Emons AMC. Cellulose microfibril deposition: coordinated activity at the plant plasma membrane. J Microsc 2008; 231:192-200. [PMID: 18778417 DOI: 10.1111/j.1365-2818.2008.02035.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Plant cell wall production is a membrane-bound process. Cell walls are composed of cellulose microfibrils, embedded inside a matrix of other polysaccharides and glycoproteins. The cell wall matrix is extruded into the existing cell wall by exocytosis. This same process also inserts the cellulose synthase complexes into the plasma membrane. These complexes, the nanomachines that produce the cellulose microfibrils, move inside the plasma membrane leaving the cellulose microfibrils in their wake. Cellulose microfibril angle is an important determinant of cell development and of tissue properties and as such relevant for the industrial use of plant material. Here, we provide an integrated view of the events taking place in the not more than 100 nm deep area in and around the plasma membrane, correlating recent results provided by the distinct field of plant cell biology. We discuss the coordinated activities of exocytosis, endocytosis, and movement of cellulose synthase complexes while producing cellulose microfibrils and the link of these processes to the cortical microtubules.
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Affiliation(s)
- J Lindeboom
- Laboratory of Plant Cell Biology, Wageningen University, Arboretumlaan 4, 6703 BD, Wageningen, The Netherlands
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49
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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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50
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Ambrose JC, Wasteneys GO. CLASP modulates microtubule-cortex interaction during self-organization of acentrosomal microtubules. Mol Biol Cell 2008; 19:4730-7. [PMID: 18716054 DOI: 10.1091/mbc.e08-06-0665] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
CLASP proteins associate with either the plus ends or sidewalls of microtubules depending on the subcellular location and cell type. In plant cells, CLASP's distribution along the full length of microtubules corresponds with the uniform anchorage of microtubules to the cell cortex. Using live cell imaging, we show here that loss of CLASP in Arabidopsis thaliana results in partial detachment of microtubules from the cortex. The detached portions undergo extensive waving, distortion, and changes in orientation, particularly when exposed to the forces of cytoplasmic streaming. These deviations from the normal linear polymerization trajectories increase the likelihood of intermicrotubule encounters that are favorable for subsequent bundle formation. Consistent with this, cortical microtubules in clasp-1 leaf epidermal cells are hyper-parallel. On the basis of these data, we identify a novel mechanism where modulation of CLASP activity governs microtubule-cortex attachment, thereby contributing to self-organization of cortical microtubules.
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