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Yang L, Liu J, Wong CK, Lim BL. Movement of Lipid Droplets in the Arabidopsis Pollen Tube Is Dependent on the Actomyosin System. PLANTS (BASEL, SWITZERLAND) 2023; 12:2489. [PMID: 37447050 DOI: 10.3390/plants12132489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 06/23/2023] [Accepted: 06/26/2023] [Indexed: 07/15/2023]
Abstract
The growth of pollen tubes, which depends on actin filaments, is pivotal for plant reproduction. Pharmacological experiments showed that while oryzalin and brefeldin A treatments had no significant effect on the lipid droplets (LDs) trafficking, while 2,3-butanedione monoxime (BDM), latrunculin B, SMIFH2, and cytochalasin D treatments slowed down LDs trafficking, in such a manner that only residual wobbling was observed, suggesting that trafficking of LDs in pollen tube is related to F-actin. While the trafficking of LDs in the wild-type pollen tubes and in myo11-2, myo11b1-1, myo11c1-1, and myo11c2-1 single mutants and myo11a1-1/myo11a2-1 double mutant were normal, their trafficking slowed down in a myosin-XI double knockout (myo11c1-1/myo11c2-1) mutant. These observations suggest that Myo11C1 and Myo11C2 motors are involved in LDs movement in pollen tubes, and they share functional redundancy. Hence, LDs movement in Arabidopsis pollen tubes relies on the actomyosin system.
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Affiliation(s)
- Lang Yang
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China
| | - Jinhong Liu
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China
| | - Ching-Kiu Wong
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China
| | - Boon Leong Lim
- School of Biological Sciences, University of Hong Kong, Pokfulam, Hong Kong, China
- State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China
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2
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Duan Z, Tominaga M. Actin-myosin XI: an intracellular control network in plants. Biochem Biophys Res Commun 2018; 506:403-408. [PMID: 29307817 DOI: 10.1016/j.bbrc.2017.12.169] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 12/31/2017] [Indexed: 11/29/2022]
Abstract
Actin is one of the three major cytoskeletal components in eukaryotic cells. Myosin XI is an actin-based motor protein in plant cells. Organelles are attached to myosin XI and translocated along the actin filaments. This dynamic actin-myosin XI system plays a major role in subcellular organelle transport and cytoplasmic streaming. Previous studies have revealed that myosin-driven transport and the actin cytoskeleton play essential roles in plant cell growth. Recent data have indicated that the actin-myosin XI cytoskeleton is essential for not only cell growth but also reproductive processes and responses to the environment. In this review, we have summarized previous reports regarding the role of the actin-myosin XI cytoskeleton in cytoplasmic streaming and plant development and recent advances in the understanding of the functions of actin-myosin XI cytoskeleton in Arabidopsis thaliana.
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Affiliation(s)
- Zhongrui Duan
- Faculty of Education and Integrated Arts and Sciences, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan
| | - Motoki Tominaga
- Faculty of Education and Integrated Arts and Sciences, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan; Major in Integrative Bioscience and Biomedical Engineering, Graduate School of Science and Engineering, Waseda University, 2-2 Wakamatsu-cho, Shinjuku-ku, Tokyo, 162-8480, Japan.
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3
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Qu X, Zhang R, Zhang M, Diao M, Xue Y, Huang S. Organizational Innovation of Apical Actin Filaments Drives Rapid Pollen Tube Growth and Turning. MOLECULAR PLANT 2017; 10:930-947. [PMID: 28502709 DOI: 10.1016/j.molp.2017.05.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Revised: 04/15/2017] [Accepted: 05/01/2017] [Indexed: 06/07/2023]
Abstract
Polarized tip growth is a fundamental cellular process in many eukaryotes. In this study, we examined the dynamic restructuring of the actin cytoskeleton and its relationship to vesicle transport during pollen tip growth in Arabidopsis. We found that actin filaments originating from the apical membrane form a specialized structure consisting of longitudinally aligned actin bundles at the cortex and inner cytoplasmic filaments with a distinct distribution. Using actin-based pharmacological treatments and genetic mutants in combination with FRAP (fluorescence recovery after photobleaching) technology to visualize the transport of vesicles within the growth domain of pollen tubes, we demonstrated that cortical actin filaments facilitate tip-ward vesicle transport. We also discovered that the inner apical actin filaments prevent backward movement of vesicles, thus ensuring that sufficient vesicles accumulate at the pollen tube tip to support the rapid growth of the pollen tube. The combinatorial effect of cortical and internal apical actin filaments perfectly explains the generation of the inverted "V" cone-shaped vesicle distribution pattern at the pollen tube tip. When pollen tubes turn, apical actin filaments at the facing side undergo depolymerization and repolymerization to reorient the apical actin structure toward the new growth direction. This actin restructuring precedes vesicle accumulation and changes in tube morphology. Thus, our study provides new insights into the functional relationship between actin dynamics and vesicle transport during rapid and directional pollen tube growth.
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Affiliation(s)
- Xiaolu Qu
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Ruihui Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Meng Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China; Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Min Diao
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China; Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Yongbiao Xue
- State Key Laboratory of Molecular Developmental Biology, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China; Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing 100101, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China; Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China.
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4
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Di Donato M, Amari K. Analysis of the role of myosins in targeting proteins to plasmodesmata. Methods Mol Biol 2015; 1217:283-93. [PMID: 25287211 DOI: 10.1007/978-1-4939-1523-1_19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
Plasmodesmata (PD) are dynamic cell wall microchannels that facilitate the intercellular trafficking of RNA and protein macromolecules playing cell nonautonomous roles in the orchestration of plant development, growth, and plant defense. The trafficking of macromolecules and organelles within cells depends on cytoskeletal components and their associated motor proteins. Plant viruses evolved to hijack this transport system to move their infectious genomes to PD. Current efforts concentrate on dissecting the role of specific myosin motors in transporting plant or viral proteins to the channels. Here we describe a method that addresses the role of specific myosins by expression of myosin tails that cause the repression of myosin activity in a dominant-negative manner. As an example, we explain the use of myosin tails from Nicotiana benthamiana to address the role of N. benthamiana myosins in the targeting of PLASMODESMATA-LOCATED PROTEIN 1 (PDLP1) to PD.
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Affiliation(s)
- Martin Di Donato
- Department of Biology-Plant Biology, University of Fribourg, CH-1700, Fribourg, Switzerland
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5
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Era A, Kutsuna N, Higaki T, Hasezawa S, Nakano A, Ueda T. Microtubule stability affects the unique motility of F-actin in Marchantia polymorpha. JOURNAL OF PLANT RESEARCH 2013; 126:113-119. [PMID: 22678689 DOI: 10.1007/s10265-012-0496-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2011] [Accepted: 04/20/2012] [Indexed: 06/01/2023]
Abstract
Actin microfilaments play crucial roles in diverse plant functions. Some specific cellular processes require interaction between F-actin and microtubules, and it is believed that there are direct or indirect connections between F-actin and microtubules. We previously reported that actin microfilaments exhibit unique dynamic motility in cells of the liverwort, Marchantia polymorpha; the relevance of this activity to microtubules has not been explored. To examine whether the dynamics of F-actin in M. polymorpha were somehow regulated by microtubules, we investigated the effects of stabilization or destabilization of microtubules on dynamics of actin bundles, which were visualized by Lifeact-Venus. To our surprise, both stabilization and destabilization of microtubules exerted similar effects on F-actin motility; apparent sliding movement of F-actin in M. polymorpha cells was accelerated by both oryzalin and paclitaxel, with the effect of paclitaxel more evident than that of oryzalin. Immunofluorescence staining revealed that some F-actin bundles were arrayed along with microtubules in M. polymorpha thallus cells. These results suggest that microtubules play regulatory roles in the unique F-actin dynamics in M. polymorpha.
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Affiliation(s)
- Atsuko Era
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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6
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White RG, Barton DA. The cytoskeleton in plasmodesmata: a role in intercellular transport? JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:5249-66. [PMID: 21862484 DOI: 10.1093/jxb/err227] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Actin and myosin are components of the plant cell cytoskeleton that extend from cell to cell through plasmodesmata (PD), but it is unclear how they are organized within the cytoplasmic sleeve or how they might behave as regulatory elements. Early work used antibodies to locate actin and myosin to PD, at the electron microscope level, or to pitfields (aggregations of PD in the cell wall), using immunofluorescence techniques. More recently, a green fluorescent protein (GFP)-tagged plant myosin VIII was located specifically at PD-rich pitfields in cell walls. Application of actin or myosin disrupters may modify the conformation of PD and alter rates of cell-cell transport, providing evidence for a role in regulating PD permeability. Intriguingly, there is now evidence of differentiation between types of PD, some of which open in response to both actin and myosin disrupters, and others which are unaffected by actin disrupters or which close in response to myosin inhibitors. Viruses also interact with elements of the cytoskeleton for both intracellular and intercellular transport. The precise function of the cytoskeleton in PD may change during cell development, and may not be identical in all tissue types, or even in all PD within a single cell. Nevertheless, it is likely that actin- and myosin-associated proteins play a key role in regulating cell-cell transport, by interacting with cargo and loading it into PD, and may underlie the capacity for one-way transport across particular cell and tissue boundaries.
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Affiliation(s)
- Rosemary G White
- Commonwealth Scientific and Industrial Research Organisation, Division of Plant Industry, Canberra, ACT 2601, Australia.
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7
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Hydrodynamic property of the cytoplasm is sufficient to mediate cytoplasmic streaming in the Caenorhabditis elegans embryo. Proc Natl Acad Sci U S A 2011; 108:11900-5. [PMID: 21730185 DOI: 10.1073/pnas.1101853108] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cytoplasmic streaming is a type of intracellular transport widely seen in nature. Cytoplasmic streaming in Caenorhabditis elegans at the one-cell stage is bidirectional; the flow near the cortex ("cortical flow") is oriented toward the anterior, whereas the flow in the central region ("cytoplasmic flow") is oriented toward the posterior. Both cortical flow and cytoplasmic flow depend on non-muscle-myosin II (NMY-2), which primarily localizes in the cortex. The manner in which NMY-2 proteins drive cytoplasmic flow in the opposite direction from remote locations has not been fully understood. In this study, we demonstrated that the hydrodynamic properties of the cytoplasm are sufficient to mediate the forces generated by the cortical myosin to drive bidirectional streaming throughout the cytoplasm. We quantified the flow velocities of cytoplasmic streaming using particle image velocimetry (PIV) and conducted a three-dimensional hydrodynamic simulation using the moving particle semiimplicit method. Our simulation quantitatively reconstructed the quantified flow velocity distribution resolved through PIV analysis. Furthermore, our PIV analyses detected microtubule-dependent flows during the pronuclear migration stage. These flows were reproduced via hydrodynamic interactions between moving pronuclei and the cytoplasm. The agreement of flow dynamics in vivo and in simulation indicates that the hydrodynamic properties of the cytoplasm are sufficient to mediate cytoplasmic streaming in C. elegans embryos.
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8
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Klima A, Foissner I. Actin-dependent deposition of putative endosomes and endoplasmic reticulum during early stages of wound healing in characean internodal cells. PLANT BIOLOGY (STUTTGART, GERMANY) 2011; 13:590-601. [PMID: 21668600 PMCID: PMC3284245 DOI: 10.1111/j.1438-8677.2010.00413.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
We investigated the behaviour of organelles stained with FM1-43 (putative endosomes) and/or LysoTracker Red (LTred; acidic compartments) and of the endoplasmic reticulum (ER) during healing of puncture and UV-induced wounds in internodal cells of Nitella flexilis and Chara corallina. Immediately after puncture, wounds were passively sealed with a plug of solid vacuolar inclusions, onto which a bipartite wound wall was actively deposited. The outer, callose-containing amorphous layer consisted of remnants of FM1-43- and LTred-labelled organelles, ER cisternae and polysaccharide-containing secretory vesicles, which became deposited in the absence of membrane retrieval (compound exocytosis). During formation of the inner cellulosic layer, exocytosis of secretory vesicles with the newly formed plasma membrane is coupled to endocytosis via coated vesicles. Migration of FM1-43- and LTred-stained organelles, ER and secretory vesicles towards the cell cortex and deposition of a bipartite wound wall could also be induced by spot-like irradiation with ultraviolet light. Cytochalasin D reversibly inhibited the accumulation and deposition of organelles. Our study indicates that active actin-dependent deposition of putative recycling endosomes is required for wound healing (plasma membrane repair) and supports the hypothesis that deposition of ER cisternae helps to restore wounding-disturbed Ca(2+) metabolism.
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Affiliation(s)
- A Klima
- Division of Plant Physiology, Department of Cell Biology, University of Salzburg, Hellbrunnerstrasse 34, Salzburg, Austria
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Radford JE, White RG. Inhibitors of myosin, but not actin, alter transport through Tradescantia plasmodesmata. PROTOPLASMA 2011; 248:205-16. [PMID: 21113638 DOI: 10.1007/s00709-010-0244-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2010] [Accepted: 11/10/2010] [Indexed: 05/13/2023]
Abstract
Actin and myosin are components of plasmodesmata, the cytoplasmic channels between plant cells, but their role in regulating these channels is unclear. Here, we investigated the role of myosin in regulating plasmodesmata in a well-studied, simple system comprising single filaments of cells which form stamen hairs in Tradescantia virginiana flowers. Effects of myosin inhibitors were assessed by analysing cell-to-cell movement of fluorescent tracers microinjected into treated cells. Incubation in the myosin inhibitor, 2,3-butanedione monoxime (BDM) or injection of anti-myosin antibodies increased cell-cell transport of fluorescent dextrans, while treatment with the myosin inhibitor N-ethylmaleimide (NEM) decreased cell-cell transport. Pretreatment with the callose synthesis inhibitor, deoxy-D: -glucose (DDG), enhanced transport induced by BDM treatment or injection of myosin antibodies but did not relieve NEM-induced reduction in transport. In contrast to the myosin inhibitors, cell-to-cell transport was unaffected by treatment with the actin polymerisation inhibitor, latrunculin B, after controlling for callose synthesis with DDG. Transport was increased following azide treatment, and reduced after injection of ATP, as in previous studies. We propose that myosin detachment from actin, induced by BDM, opens T. virginiana plasmodesmata whereas the firm attachment of myosin to actin, promoted by NEM, closes them.
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Affiliation(s)
- Janine E Radford
- Department of Biological Sciences, Monash University, Melbourne, VIC, 3800, Australia
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10
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van der Honing HS, de Ruijter NCA, Emons AMC, Ketelaar T. Actin and myosin regulate cytoplasm stiffness in plant cells: a study using optical tweezers. THE NEW PHYTOLOGIST 2010; 185:90-102. [PMID: 19761443 DOI: 10.1111/j.1469-8137.2009.03017.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Here, we produced cytoplasmic protrusions with optical tweezers in mature BY-2 suspension cultured cells to study the parameters involved in the movement of actin filaments during changes in cytoplasmic organization and to determine whether stiffness is an actin-related property of plant cytoplasm. Optical tweezers were used to create cytoplasmic protrusions resembling cytoplasmic strands. Simultaneously, the behavior of the actin cytoskeleton was imaged. After actin filament depolymerization, less force was needed to create cytoplasmic protrusions. During treatment with the myosin ATPase inhibitor 2,3-butanedione monoxime, more trapping force was needed to create and maintain cytoplasmic protrusions. Thus, the presence of actin filaments and, even more so, the deactivation of a 2,3-butanedione monoxime-sensitive factor, probably myosin, stiffens the cytoplasm. During 2,3-butanedione monoxime treatment, none of the tweezer-formed protrusions contained filamentous actin, showing that a 2,3-butanedione monoxime-sensitive factor, probably myosin, is responsible for the movement of actin filaments, and implying that myosin serves as a static cross-linker of actin filaments when its motor function is inhibited. The presence of actin filaments does not delay the collapse of cytoplasmic protrusions after tweezer release. Myosin-based reorganization of the existing actin cytoskeleton could be the basis for new cytoplasmic strand formation, and thus the production of an organized cytoarchitecture.
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Affiliation(s)
- Hannie S van der Honing
- Laboratory of Plant Cell Biology, Wageningen University, Building 107, Radix W1, Droevendaalsesteeg 1, 6708PB Wageningen, The Netherlands
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11
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Natesan SKA, Sullivan JA, Gray JC. Myosin XI is required for actin-associated movement of plastid stromules. MOLECULAR PLANT 2009; 2:1262-72. [PMID: 19995729 DOI: 10.1093/mp/ssp078] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Stromules are highly dynamic stroma-filled tubules extending from the surface of plastids and occasionally interconnecting individual plastids, allowing the movement of complex biological molecules between the interconnected plastids. Experiments with inhibitors of cytoskeleton assembly have indicated the involvement of an actin-based system in stromule movement. However, the motor protein associated with the system had not been identified. Here, we present direct evidence that myosin XI is involved in the formation and movement of stromules in tobacco leaves. Application of 2,3-butanedione 2-monoxime, an inhibitor of myosin ATPase activity, resulted in the loss of stromules from tobacco leaf epidermal cells. Transient RNA interference of myosin XI in leaves of Nicotiana benthamiana also resulted in the loss of stromules from epidermal cells, without any effect on transcripts for actin or myosin VIII. Transient expression of a GFP-tagged myosin XI tail domain in tobacco leaf epidermal cells showed that the fusion protein localized to the chloroplast envelope, as well as to mitochondria and other organelles. Our findings identify myosin XI as a key protein involved in the formation and movement of stromules.
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Affiliation(s)
- Senthil Kumar A Natesan
- Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK
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12
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Henson JH, Cheung D, Fried CA, Shuster CB, McClellan MK, Voss MK, Sheridan JT, Oldenbourg R. Structure and dynamics of an Arp2/3 complex-independent component of the lamellipodial actin network. ACTA ACUST UNITED AC 2009; 66:679-92. [PMID: 19530177 DOI: 10.1002/cm.20398] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Sea urchin coelomocytes contain an unusually broad lamellipodial region and have served as a useful model experimental system for studying the process of actin-based retrograde/centripetal flow. In the current study the small molecule drug 2,3-butanedione monoxime (BDM) was employed as a means of delocalizing the Arp2/3 complex from the cell edge in an effort to investigate the Arp2/3 complex-independent aspects of retrograde flow. Digitally-enhanced phase contrast, fluorescence and polarization light microscopy, along with rotary shadow transmission electron microscopy methods demonstrated that BDM treatment resulted in the centripetal displacement of the Arp2/3 complex and the associated dendritic lamellipodial (LP) actin network from the cell edge. In its wake there remained an array of elongate actin filaments organized into concave arcs that displayed retrograde flow at approximately one quarter the normal rate. Actin polymerization inhibitor experiments indicated that these arcs were generated by polymerization at the cell edge, while active myosin-based contraction in BDM treated cells was demonstrated by localization with antiphospho-myosin regulatory light chain (MRLC) antibody, the retraction of the cytoskeleton in the presence of BDM, and the response of the BDM arcs to laser-based severing. The results suggest that BDM treatment reveals an Arp2/3 complex-independent actin structure in coelomocytes consisting of elongate filaments integrated into the LP network and that these filaments represent a potential connection between the LP network and the central cytoskeleton.
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Affiliation(s)
- John H Henson
- Department of Biology, Dickinson College, Carlisle, PA 17013, USA.
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13
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Zheng M, Beck M, Müller J, Chen T, Wang X, Wang F, Wang Q, Wang Y, Baluška F, Logan DC, Šamaj J, Lin J. Actin turnover is required for myosin-dependent mitochondrial movements in Arabidopsis root hairs. PLoS One 2009; 4:e5961. [PMID: 19536333 PMCID: PMC2694364 DOI: 10.1371/journal.pone.0005961] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2009] [Accepted: 05/19/2009] [Indexed: 12/04/2022] Open
Abstract
Background Previous studies have shown that plant mitochondrial movements are myosin-based along actin filaments, which undergo continuous turnover by the exchange of actin subunits from existing filaments. Although earlier studies revealed that actin filament dynamics are essential for many functions of the actin cytoskeleton, there are little data connecting actin dynamics and mitochondrial movements. Methodology/Principal Findings We addressed the role of actin filament dynamics in the control of mitochondrial movements by treating cells with various pharmaceuticals that affect actin filament assembly and disassembly. Confocal microscopy of Arabidopsis thaliana root hairs expressing GFP-FABD2 as an actin filament reporter showed that mitochondrial distribution was in agreement with the arrangement of actin filaments in root hairs at different developmental stages. Analyses of mitochondrial trajectories and instantaneous velocities immediately following pharmacological perturbation of the cytoskeleton using variable-angle evanescent wave microscopy and/or spinning disk confocal microscopy revealed that mitochondrial velocities were regulated by myosin activity and actin filament dynamics. Furthermore, simultaneous visualization of mitochondria and actin filaments suggested that mitochondrial positioning might involve depolymerization of actin filaments on the surface of mitochondria. Conclusions/Significance Base on these results we propose a mechanism for the regulation of mitochondrial speed of movements, positioning, and direction of movements that combines the coordinated activity of myosin and the rate of actin turnover, together with microtubule dynamics, which directs the positioning of actin polymerization events.
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Affiliation(s)
- Maozhong Zheng
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- Graduate School of Chinese Academy of Sciences, Beijing, China
| | - Martina Beck
- Institute of Cellular and Molecular Botany, Rheinische Friedrich-Wilhelms-University Bonn, Department of Plant Cell Biology, Bonn, Germany
| | - Jens Müller
- Institute of Cellular and Molecular Botany, Rheinische Friedrich-Wilhelms-University Bonn, Department of Plant Cell Biology, Bonn, Germany
| | - Tong Chen
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Xiaohua Wang
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- Graduate School of Chinese Academy of Sciences, Beijing, China
| | - Feng Wang
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- Graduate School of Chinese Academy of Sciences, Beijing, China
| | - Qinli Wang
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Yuqing Wang
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- Graduate School of Chinese Academy of Sciences, Beijing, China
| | - František Baluška
- Institute of Cellular and Molecular Botany, Rheinische Friedrich-Wilhelms-University Bonn, Department of Plant Cell Biology, Bonn, Germany
- Institute of Botany, Slovak Academy of Sciences, Bratislava, Slovak Republic
| | - David C. Logan
- Department of Biology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Jozef Šamaj
- Institute of Cellular and Molecular Botany, Rheinische Friedrich-Wilhelms-University Bonn, Department of Plant Cell Biology, Bonn, Germany
- Institute of Plant Genetics and Biotechnology, Slovak Academy of Sciences, Nitra, Slovak Republic
- Faculty of Science, Palacký University Olomouc, Olomouc, Czech Republic
| | - Jinxing Lin
- Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- * E-mail:
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Era A, Tominaga M, Ebine K, Awai C, Saito C, Ishizaki K, Yamato KT, Kohchi T, Nakano A, Ueda T. Application of Lifeact reveals F-actin dynamics in Arabidopsis thaliana and the liverwort, Marchantia polymorpha. PLANT & CELL PHYSIOLOGY 2009; 50:1041-8. [PMID: 19369273 PMCID: PMC2694730 DOI: 10.1093/pcp/pcp055] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Accepted: 04/10/2009] [Indexed: 05/18/2023]
Abstract
Actin plays fundamental roles in a wide array of plant functions, including cell division, cytoplasmic streaming, cell morphogenesis and organelle motility. Imaging the actin cytoskeleton in living cells is a powerful methodology for studying these important phenomena. Several useful probes for live imaging of filamentous actin (F-actin) have been developed, but new versatile probes are still needed. Here, we report the application of a new probe called Lifeact for visualizing F-actin in plant cells. Lifeact is a short peptide comprising 17 amino acids that was derived from yeast Abp140p. We used a Lifeact-Venus fusion protein for staining F-actin in Arabidopsis thaliana and were able to observe dynamic rearrangements of the actin meshwork in root hair cells. We also used Lifeact-Venus to visualize the actin cytoskeleton in the liverwort Marchantia polymorpha; this revealed unique and dynamic F-actin motility in liverwort cells. Our results suggest that Lifeact could be a useful tool for studying the actin cytoskeleton in a wide range of plant lineages.
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Affiliation(s)
- Atsuko Era
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033 Japan
| | - Motoki Tominaga
- Molecular Membrane Biology Laboratory, RIKEN Advanced Science Institute, Wako, Saitama, 351-0198 Japan
| | - Kazuo Ebine
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033 Japan
| | - Chie Awai
- Molecular Membrane Biology Laboratory, RIKEN Advanced Science Institute, Wako, Saitama, 351-0198 Japan
| | - Chieko Saito
- Molecular Membrane Biology Laboratory, RIKEN Advanced Science Institute, Wako, Saitama, 351-0198 Japan
| | | | | | - Takayuki Kohchi
- Graduate School of Biostudies, Kyoto University, Kyoto, 606-8502 Japan
| | - Akihiko Nakano
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033 Japan
- Molecular Membrane Biology Laboratory, RIKEN Advanced Science Institute, Wako, Saitama, 351-0198 Japan
| | - Takashi Ueda
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Bunkyo-ku, Tokyo, 113-0033 Japan
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Foissner I, Menzel D, Wasteneys GO. Microtubule-dependent motility and orientation of the cortical endoplasmic reticulum in elongating characean internodal cells. ACTA ACUST UNITED AC 2009; 66:142-55. [PMID: 19137584 DOI: 10.1002/cm.20337] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Motility of the endoplasmic reticulum (ER) is predominantly microtubule- dependent in animal cells but thought to be entirely actomyosin-dependent in plant cells. Using live cell imaging and transmission electron microscopy to examine ER motility and structural organization in giant internodal cells of characean algae, we discovered that at the onset of cell elongation, the cortical ER situated near the plasma membrane formed a tight meshwork of predominantly transverse ER tubules that frequently coaligned with microtubules. Microtubule depolymerization increased mesh size and decreased the dynamics of the cortical ER. In contrast, perturbing the cortical actin array with cytochalasins did not affect the transverse orientation but decreased mesh size and increased ER dynamics. Our data suggest that myosin-dependent ER motility is confined to the ER strands in the streaming endoplasm, while the more sedate cortical ER uses microtubule-based mechanisms for organization and motility during early stages of cell elongation. We show further that the ER has an inherent, NEM-sensitive dynamics which can be altered via interaction with the cytoskeleton and that tubule formation and fusion events are cytoskeleton-independent.
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Affiliation(s)
- Ilse Foissner
- Department of Cell Biology, University of Salzburg, Austria.
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16
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Staiger CJ, Sheahan MB, Khurana P, Wang X, McCurdy DW, Blanchoin L. Actin filament dynamics are dominated by rapid growth and severing activity in the Arabidopsis cortical array. ACTA ACUST UNITED AC 2009; 184:269-80. [PMID: 19171759 PMCID: PMC2654301 DOI: 10.1083/jcb.200806185] [Citation(s) in RCA: 189] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Metazoan cells harness the power of actin dynamics to create cytoskeletal arrays that stimulate protrusions and drive intracellular organelle movements. In plant cells, the actin cytoskeleton is understood to participate in cell elongation; however, a detailed description and molecular mechanism(s) underpinning filament nucleation, growth, and turnover are lacking. Here, we use variable-angle epifluorescence microscopy (VAEM) to examine the organization and dynamics of the cortical cytoskeleton in growing and nongrowing epidermal cells. One population of filaments in the cortical array, which most likely represent single actin filaments, is randomly oriented and highly dynamic. These filaments grow at rates of 1.7 µm/s, but are generally short-lived. Instead of depolymerization at their ends, actin filaments are disassembled by severing activity. Remodeling of the cortical actin array also features filament buckling and straightening events. These observations indicate a mechanism inconsistent with treadmilling. Instead, cortical actin filament dynamics resemble the stochastic dynamics of an in vitro biomimetic system for actin assembly.
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Affiliation(s)
- Christopher J Staiger
- Department of Biological Sciences, Hansen Life Sciences Research Building, Purdue University, West Lafayette, IN 47907, USA
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17
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Yokota E, Ueda S, Tamura K, Orii H, Uchi S, Sonobe S, Hara-Nishimura I, Shimmen T. An isoform of myosin XI is responsible for the translocation of endoplasmic reticulum in tobacco cultured BY-2 cells. JOURNAL OF EXPERIMENTAL BOTANY 2008; 60:197-212. [PMID: 19039101 PMCID: PMC3071767 DOI: 10.1093/jxb/ern280] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Revised: 10/14/2008] [Accepted: 10/16/2008] [Indexed: 05/18/2023]
Abstract
The involvement of myosin XI in generating the motive force for cytoplasmic streaming in plant cells is becoming evident. For a comprehensive understanding of the physiological roles of myosin XI isoforms, it is necessary to elucidate the properties and functions of each isoform individually. In tobacco cultured BY-2 cells, two types of myosins, one composed of 175 kDa heavy chain (175 kDa myosin) and the other of 170 kDa heavy chain (170 kDa myosin), have been identified biochemically and immunocytochemically. From sequence analyses of cDNA clones encoding heavy chains of 175 kDa and 170 kDa myosin, both myosins have been classified as myosin XI. Immunocytochemical studies using a polyclonal antibody against purified 175 kDa myosin heavy chain showed that the 175 kDa myosin is distributed throughout the cytoplasm as fine dots in interphase BY-2 cells. During mitosis, some parts of 175 kDa myosin were found to accumulate in the pre-prophase band (PPB), spindle, the equatorial plane of a phragmoplast and on the circumference of daughter nuclei. In transgenic BY-2 cells, in which an endoplasmic reticulum (ER)-specific retention signal, HDEL, tagged with green fluorescent protein (GFP) was stably expressed, ER showed a similar behaviour to that of 175 kDa myosin. Furthermore, this myosin was co-fractionated with GFP-ER by sucrose density gradient centrifugation. From these findings, it was suggested that the 175 kDa myosin is a molecular motor responsible for translocating ER in BY-2 cells.
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Affiliation(s)
- Etsuo Yokota
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Harima Science Park City, Hyogo 678-1297, Japan.
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18
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Klima A, Foissner I. FM dyes label sterol-rich plasma membrane domains and are internalized independently of the cytoskeleton in characean internodal cells. PLANT & CELL PHYSIOLOGY 2008; 49:1508-21. [PMID: 18757863 DOI: 10.1093/pcp/pcn122] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
We applied the endocytic markers FM1-43, FM4-64 and filipin to internodal cells of the green alga Chara corallina. Both FM dyes stained stable, long-living plasma membrane patches with a diameter of up to 1 microm. After 5 min, FM dyes labeled cortical, trembling structures up to 500 nm in size. After 15 min, FM dyes localized to endoplasmic organelles up to 1 microm in diameter, which migrated actively along actin bundles or participated in cytoplasmic mass streaming. After 30-60 min, FM fluorescence appeared in the membrane of small, endoplasmic vacuoles but not in that of the central vacuole. Some of the FM-labeled organelles were also stained by neutral red and lysotracker yellow, indicative of acidic compartments. Filipin, a sterol-specific marker, likewise labeled plasma membrane domains which co-localized with the FM patches. However, internalization of filipin could not be observed. KCN, cytochalasin D, latrunculin B and oryzalin had no effect on size, shape and distribution of FM- and filipin-labeled plasma membrane domains. Internalization of FM dyes was inhibited by KCN but not by drugs which interfere with the actin or microtubule cytoskeleton. Our data indicate that the plasma membrane of characean internodal cells contains discrete domains which are enriched in sterols and probably correspond to clusters of lipid rafts. The inhibitor experiments suggest that FM uptake is active but independent of actin filaments, actin polymerization and microtubules. The possible function of the sterol-rich, FM labeled plasma membrane areas and the significance of actin-independent FM internalization (via endocytosis or energy-dependent flippases) are discussed.
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Affiliation(s)
- Andreas Klima
- Department of Cell Biology, Division of Plant Physiology, University of Salzburg, Hellbrunnerstrasse 34, A-5020 Salzburg, Austria
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19
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Shimmen T. The sliding theory of cytoplasmic streaming: fifty years of progress. JOURNAL OF PLANT RESEARCH 2007; 120:31-43. [PMID: 17252175 DOI: 10.1007/s10265-006-0061-0] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2006] [Accepted: 11/22/2006] [Indexed: 05/08/2023]
Abstract
Fifty years ago, an important paper appeared in Botanical Magazine Tokyo. Kamiya and Kuroda proposed a sliding theory for the mechanism of cytoplasmic streaming. This pioneering study laid the basis for elucidation of the molecular mechanism of cytoplasmic streaming--the motive force is generated by the sliding of myosin XI associated with organelles along actin filaments, using the hydrolysis energy of ATP. The role of the actin-myosin system in various plant cell functions is becoming evident. The present article reviews progress in studies on cytoplasmic streaming over the past 50 years.
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Affiliation(s)
- Teruo Shimmen
- Department of Life Science, Graduate School of Life Science, University of Hyogo, Harima Science Park City, Hyogo 678-1297, Japan.
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20
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Sumoza-Toledo A, Gillespie PG, Romero-Ramirez H, Ferreira-Ishikawa HC, Larson RE, Santos-Argumedo L. Differential localization of unconventional myosin I and nonmuscle myosin II during B cell spreading. Exp Cell Res 2006; 312:3312-22. [PMID: 16919270 DOI: 10.1016/j.yexcr.2006.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Revised: 07/01/2006] [Accepted: 07/07/2006] [Indexed: 02/06/2023]
Abstract
Cross-linking of CD44 in vitro promotes chemokinesis and actin-based dendrite formation in T and B cells. However, the mechanisms by which the adhesion molecule CD44 induces cytoskeleton activation in lymphocytes are still poorly understood. In this study, we have investigated whether myosin isoforms are involved in CD44-dependent dendrite formation in activated B cells. Pharmacological inhibition of myosin with 2,3-butanedione monoxime strongly affected spreading and dendrite formation, suggesting that these cellular motors may participate in these phenomena. Furthermore, immunofluorescence analysis showed differences in subcellular localization of class I and class II myosin during B cell spreading. In response to CD44 cross-linking, myosin-1c was polarized to lamellipodia, where F-actin was high. In contrast, the distribution of cytosplasmic nonmuscle class II myosin was not altered. Expressions of myosin-1c and II were also demonstrated in B cells by Western blot. Although the inhibition of PLCgamma, PI3K and MEK-1 activation affected the spreading and dendrite formation in activated B cells, only PLCgamma and MEK-1 inhibition correlated with absence of myosin-1c polarization. Additionally, myosin-1c polarization was observed upon cross-linking of other surface molecules, suggesting a common mechanism for B cell spreading. This work shows that class I and class II myosin are expressed in B cells, are differentially distributed, and may participate in the morphological changes of these cells.
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Affiliation(s)
- Adriana Sumoza-Toledo
- Department of Molecular Biomedicine, Centro de Investigación y Estudios Avanzados, Av. IPN #2508. Col. Zacatenco. CP 07360, México, D.F., México
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21
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Mancuso S, Barlow PW, Volkmann D, Baluska F. Actin turnover-mediated gravity response in maize root apices: gravitropism of decapped roots implicates gravisensing outside of the root cap. PLANT SIGNALING & BEHAVIOR 2006; 1:52-8. [PMID: 19521476 PMCID: PMC2633879 DOI: 10.4161/psb.1.2.2432] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Accepted: 10/31/2005] [Indexed: 05/08/2023]
Abstract
The dynamic actin cytoskeleton has been proposed to be linked to gravity sensing in plants but the mechanistic understanding of these processes remains unknown. We have performed detailed pharmacological analyses of the role of the dynamic actin cytoskeleton in gravibending of maize (Zea mays) root apices. Depolymerization of actin filaments with two drugs having different mode of their actions, cytochalasin D and latrunculin B, stimulated root gravibending. By contrast, drug-induced stimulation of actin polymerization and inhibition of actin turnover, using two different agents phalloidin and jasplakinolide, compromised the root gravibending. Importantly, all these actin drugs inhibited root growth to similar extents suggesting that high actin turnover is essential for the gravity-related growth responses rather than for the general growth process. Both latrunculin B and cytochalasin D treatments inhibited root growth but restored gravibending of the decapped root apices, indicating that there is a strong potential for effective actin-mediated gravity sensing outside the cap. This elusive gravity sensing outside the root cap is dependent not only on the high rate of actin turnover but also on weakening of myosin activities, as general inhibition of myosin ATPases induced stimulation of gravibending of the decapped root apices. Collectively, these data provide evidence for the actin turnover-mediated gravity sensing outside the root cap.
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Affiliation(s)
- Stefano Mancuso
- Electrophysiology Laboratory; Department of Horticulture; University of Florence; Sesto Fiorentino, Italy
| | - Peter W Barlow
- School of Biological Sciences; University of Bristol; Woodland Road; Bristol, UK
| | - Dieter Volkmann
- Rheinische Friedrich-Wilhelms-University of Bonn; Institute of Cellular and Molecular Botany; Bonn, Germany
| | - Frantisek Baluska
- Rheinische Friedrich-Wilhelms-University of Bonn; Institute of Cellular and Molecular Botany; Bonn, Germany
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22
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Sheahan MB, McCurdy DW, Rose RJ. Mitochondria as a connected population: ensuring continuity of the mitochondrial genome during plant cell dedifferentiation through massive mitochondrial fusion. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2005; 44:744-55. [PMID: 16297067 DOI: 10.1111/j.1365-313x.2005.02561.x] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Mitochondrial fusion in plants and its role in development are poorly understood. Cultured tobacco mesophyll protoplasts provide an excellent experimental system for visualizing mitochondrial dynamics. Before protoplasts first divide, mitochondria undergo a phase of extensive elongation before fission causes an increase in number, followed by actin filament (AF)-dependent dispersion that distributes mitochondria uniformly throughout the cytoplasm. Here, by fusing protoplasts containing either green fluorescent protein- or MitoTracker-labelled mitochondria, we show that elongation results from fusion during early (4-8 h) protoplast culture. This massive mitochondrial fusion (MMF) leads to near-complete mixing of the mitochondrial population within 24 h. Staining isolated mitochondria with 4',6-diamidino-2-phenylindole (DAPI) revealed that in freshly prepared protoplasts mitochondrial nucleoids were unequally distributed, with many mitochondria failing to stain with DAPI, suggesting the presence of an incomplete mitochondrial genome. Following MMF, nucleoids were distributed evenly throughout the population, thereby ensuring continuity of the mitochondrial genome in daughter cells. Massive mitochondrial fusion appears to be specific to dedifferentiation, since it also occurs in mesophyll protoplasts of Arabidopsis and Medicago but not in protoplasts from already dedifferentiated cells such as BY-2 or callus cultures. Efficient MMF requires an inner membrane electrical gradient, cytoplasmic protein synthesis, microtubules and functional kinesin but not ATP or AFs, indicating fundamental differences from mitochondrial fusion in non-plant systems. Our studies reveal that individual mitochondria are connected over time by fusion events, a finding that allows a clearer interpretation of how novel mitochondrial genotypes develop following cell fusion, and indicates that developmentally regulated fusion ensures continuity of the mitochondrial genome.
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Affiliation(s)
- Michael B Sheahan
- School of Environmental and Life Sciences, The University of Newcastle, Callaghan, NSW, Australia
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23
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Frantzios G, Galatis B, Apostolakos P. Aluminium causes variable responses in actin filament cytoskeleton of the root tip cells of Triticum turgidum. PROTOPLASMA 2005; 225:129-40. [PMID: 16228895 DOI: 10.1007/s00709-005-0100-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2004] [Accepted: 12/22/2004] [Indexed: 05/04/2023]
Abstract
The effects of aluminium on the actin filament (AF) cytoskeleton of Triticum turgidum meristematic root tip cells were examined. In short treatments (up to 2 h) with 50-1000 microM AlCl3.6H2O, interphase cells displayed numerous AFs arrayed in thick bundles that lined the plasmalemma and traversed the endoplasm in different directions. Measurements using digital image analysis and assessment of the overall AF fluorescence revealed that, in short treatments, the affected cells possessed 25-30% more AFs than the untreated ones. The thick AF bundles were not formed in the Al-treated cells in the presence of the myosin inhibitors 2,3-butanedione monoxime (BDM) and 1-(5-iodonaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine (ML-7), a fact suggesting that myosins are involved in AF bundling. In longer Al treatments, the AF bundles were disorganised, forming granular actin accumulations, a process that was completed after 4 h of treatment. In the Al-treated cells, increased amounts of callose were uniformly deposited along the whole surface of the cell walls. In contrast, callose formed local deposits in the Al-treated cells in the presence of cytochalasin B, BDM, or ML-7. These results favour the hypothesis that the actomyosin system in the Al-treated cells, among other roles, participates in the mechanism controlling callose deposition.
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Affiliation(s)
- G Frantzios
- Department of Botany, Faculty of Biology, University of Athens, Athens, Greece
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