1
|
Xu Y, Huang S. Control of the Actin Cytoskeleton Within Apical and Subapical Regions of Pollen Tubes. Front Cell Dev Biol 2020; 8:614821. [PMID: 33344460 PMCID: PMC7744591 DOI: 10.3389/fcell.2020.614821] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 11/13/2020] [Indexed: 01/07/2023] Open
Abstract
In flowering plants, sexual reproduction involves a double fertilization event, which is facilitated by the delivery of two non-motile sperm cells to the ovule by the pollen tube. Pollen tube growth occurs exclusively at the tip and is extremely rapid. It strictly depends on an intact actin cytoskeleton, and is therefore an excellent model for uncovering the molecular mechanisms underlying dynamic actin cytoskeleton remodeling. There has been a long-term debate about the organization and dynamics of actin filaments within the apical and subapical regions of pollen tube tips. By combining state-of-the-art live-cell imaging with the usage of mutants which lack different actin-binding proteins, our understanding of the origin, spatial organization, dynamics and regulation of actin filaments within the pollen tube tip has greatly improved. In this review article, we will summarize the progress made in this area.
Collapse
Affiliation(s)
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing, China
| |
Collapse
|
2
|
Qian D, Xiang Y. Actin Cytoskeleton as Actor in Upstream and Downstream of Calcium Signaling in Plant Cells. Int J Mol Sci 2019; 20:ijms20061403. [PMID: 30897737 PMCID: PMC6471457 DOI: 10.3390/ijms20061403] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 03/14/2019] [Accepted: 03/15/2019] [Indexed: 01/04/2023] Open
Abstract
In plant cells, calcium (Ca2+) serves as a versatile intracellular messenger, participating in several fundamental and important biological processes. Recent studies have shown that the actin cytoskeleton is not only an upstream regulator of Ca2+ signaling, but also a downstream regulator. Ca2+ has been shown to regulates actin dynamics and rearrangements via different mechanisms in plants, and on this basis, the upstream signaling encoded within the Ca2+ transient can be decoded. Moreover, actin dynamics have also been proposed to act as an upstream of Ca2+, adjust Ca2+ oscillations, and establish cytosolic Ca2+ ([Ca2+]cyt) gradients in plant cells. In the current review, we focus on the advances in uncovering the relationship between the actin cytoskeleton and calcium in plant cells and summarize our current understanding of this relationship.
Collapse
Affiliation(s)
- Dong Qian
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.
| | - Yun Xiang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.
| |
Collapse
|
3
|
Zhu J, Nan Q, Qin T, Qian D, Mao T, Yuan S, Wu X, Niu Y, Bai Q, An L, Xiang Y. Higher-Ordered Actin Structures Remodeled by Arabidopsis ACTIN-DEPOLYMERIZING FACTOR5 Are Important for Pollen Germination and Pollen Tube Growth. MOLECULAR PLANT 2017; 10:1065-1081. [PMID: 28606871 DOI: 10.1016/j.molp.2017.06.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 06/02/2017] [Accepted: 06/05/2017] [Indexed: 06/07/2023]
Abstract
Dynamics of the actin cytoskeleton are essential for pollen germination and pollen tube growth. ACTIN-DEPOLYMERIZING FACTORs (ADFs) typically contribute to actin turnover by severing/depolymerizing actin filaments. Recently, we demonstrated that Arabidopsis subclass III ADFs (ADF5 and ADF9) evolved F-actin-bundling function from conserved F-actin-depolymerizing function. However, little is known about the physiological function, the evolutional significance, and the actin-bundling mechanism of these neofunctionalized ADFs. Here, we report that loss of ADF5 function caused delayed pollen germination, retarded pollen tube growth, and increased sensitive to latrunculin B (LatB) treatment by affecting the generation and maintenance of actin bundles. Examination of actin filament dynamics in living cells revealed that the bundling frequency was significantly decreased in adf5 pollen tubes, consistent with its biochemical functions. Further biochemical and genetic complementation analyses demonstrated that both the N- and C-terminal actin-binding domains of ADF5 are required for its physiological and biochemical functions. Interestingly, while both are atypical actin-bundling ADFs, ADF5, but not ADF9, plays an important role in mature pollen physiological activities. Taken together, our results suggest that ADF5 has evolved the function of bundling actin filaments and plays an important role in the formation, organization, and maintenance of actin bundles during pollen germination and pollen tube growth.
Collapse
Affiliation(s)
- Jingen Zhu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Qiong Nan
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Tao Qin
- State Key Laboratory of Plant Physiology and Biochemistry, Department of Plant Sciences, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Dong Qian
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Tonglin Mao
- State Key Laboratory of Plant Physiology and Biochemistry, Department of Plant Sciences, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Shunjie Yuan
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Xiaorong Wu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yue Niu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Qifeng Bai
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Lizhe An
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Yun Xiang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.
| |
Collapse
|
4
|
Ichikawa M, Iwano M, Sato MH. Nuclear membrane localization during pollen development and apex-focused polarity establishment of SYP124/125 during pollen germination in Arabidopsis thaliana. PLANT REPRODUCTION 2015; 28:143-151. [PMID: 26111864 DOI: 10.1007/s00497-015-0265-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 06/12/2015] [Indexed: 06/04/2023]
Abstract
Establishment of apex-polarity. Elongation of the pollen tube is a highly coordinated process involving polarized secretion of cell wall and membrane materials to the apical region. We investigated changes in the localization of soluble NSF attachment proteins (SNAREs) in developing pollen grains and the pollen tube for transgenic Arabidopsis expressing pollen-specific plasma-membrane Qa-SNAREs (SYP124, 125 and 131) fused with the green fluorescent protein (GFP). The expression of SYP124 and SYP125 was firstly detected in the microspore nuclear membrane during pollen mitosis II. Although SYP124, 125 and 131 accumulated throughout the cytosol in the mature pollen grain, GFP-SYP124 and GFP-SYP125 were highly concentrated in the apical or subapical regions of the elongating pollen tube with slightly different localization patterns, whereas GFP-SYP131 was uniformly localized to the plasma membrane of the pollen tube. The apex-focused polarity of GFP-SYP125 was established coincident with formation of a Ca(2+) gradient before pollen germination. These results suggest that SNAREs function differentially in the same cells and that at least two distinct membrane transport pathways are involved in the pollen development and the pollen tube germination and elongation.
Collapse
Affiliation(s)
- Mie Ichikawa
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, 606-8522, Japan
| | - Megumi Iwano
- Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma, Nara, 630-0101, Japan
- The Institute of Scientific and Industrial Research, Osaka University, Mihogaoka 8-1, Ibaraki, Osaka, 567-0047, Japan
| | - Masa H Sato
- Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto, 606-8522, Japan.
| |
Collapse
|
5
|
Qian D, Nan Q, Yang Y, Li H, Zhou Y, Zhu J, Bai Q, Zhang P, An L, Xiang Y. Gelsolin-Like Domain 3 Plays Vital Roles in Regulating the Activities of the Lily Villin/Gelsolin/Fragmin Superfamily. PLoS One 2015; 10:e0143174. [PMID: 26587673 PMCID: PMC4654503 DOI: 10.1371/journal.pone.0143174] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Accepted: 11/02/2015] [Indexed: 02/08/2023] Open
Abstract
The villin/gelsolin/fragmin superfamily is a major group of Ca2+-dependent actin-binding proteins (ABPs) involved in various cellular processes. Members of this superfamily typically possess three or six tandem gelsolin-like (G) domains, and each domain plays a distinct role in actin filament dynamics. Although the activities of most G domains have been characterized, the biochemical function of the G3 domain remains poorly understood. In this study, we carefully compared the detailed biochemical activities of ABP29 (a new member of this family that contains the G1-G2 domains of lily ABP135) and ABP135G1-G3 (which contains the G1-G3 domains of lily ABP135). In the presence of high Ca2+ levels in vitro (200 and 10 μM), ABP135G1-G3 exhibited greater actin severing and/or depolymerization and nucleating activities than ABP29, and these proteins had similar actin capping activities. However, in the presence of low levels of Ca2+ (41 nM), ABP135G1-G3 had a weaker capping activity than ABP29. In addition, ABP29 inhibited F-actin depolymerization, as shown by dilution-mediated depolymerization assay, differing from the typical superfamily proteins. In contrast, ABP135G1-G3 accelerated F-actin depolymerization. All of these results demonstrate that the G3 domain plays specific roles in regulating the activities of the lily villin/gelsolin/fragmin superfamily proteins.
Collapse
Affiliation(s)
- Dong Qian
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Qiong Nan
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Yueming Yang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Hui Li
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Yuelong Zhou
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Jingen Zhu
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Qifeng Bai
- College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
| | - Pan Zhang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Lizhe An
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| | - Yun Xiang
- MOE Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, 730000, China
| |
Collapse
|
6
|
Qu X, Jiang Y, Chang M, Liu X, Zhang R, Huang S. Organization and regulation of the actin cytoskeleton in the pollen tube. FRONTIERS IN PLANT SCIENCE 2015; 5:786. [PMID: 25620974 PMCID: PMC4287052 DOI: 10.3389/fpls.2014.00786] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/29/2014] [Accepted: 12/17/2014] [Indexed: 05/18/2023]
Abstract
Proper organization of the actin cytoskeleton is crucial for pollen tube growth. However, the precise mechanisms by which the actin cytoskeleton regulates pollen tube growth remain to be further elucidated. The functions of the actin cytoskeleton are dictated by its spatial organization and dynamics. However, early observations of the distribution of actin filaments at the pollen tube apex were quite perplexing, resulting in decades of controversial debate. Fortunately, due to improvements in fixation regimens for staining actin filaments in fixed pollen tubes, as well as the adoption of appropriate markers for visualizing actin filaments in living pollen tubes, this issue has been resolved and has given rise to the consensus view of the spatial distribution of actin filaments throughout the entire pollen tube. Importantly, recent descriptions of the dynamics of individual actin filaments in the apical region have expanded our understanding of the function of actin in regulation of pollen tube growth. Furthermore, careful documentation of the function and mode of action of several actin-binding proteins expressed in pollen have provided novel insights into the regulation of actin spatial distribution and dynamics. In the current review, we summarize our understanding of the organization, dynamics, and regulation of the actin cytoskeleton in the pollen tube.
Collapse
Affiliation(s)
- Xiaolu Qu
- Center for Plant Biology, School of Life Sciences, Tsinghua UniversityBeijing, China
| | - Yuxiang Jiang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany – Chinese Academy of SciencesBeijing, China
| | - Ming Chang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany – Chinese Academy of SciencesBeijing, China
| | - Xiaonan Liu
- Key Laboratory of Plant Molecular Physiology, Institute of Botany – Chinese Academy of SciencesBeijing, China
| | - Ruihui Zhang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany – Chinese Academy of SciencesBeijing, China
| | - Shanjin Huang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany – Chinese Academy of SciencesBeijing, China
| |
Collapse
|
7
|
Huang S, Qu X, Zhang R. Plant villins: versatile actin regulatory proteins. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2015; 57:40-9. [PMID: 25294278 DOI: 10.1111/jipb.12293] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2014] [Accepted: 10/01/2014] [Indexed: 05/03/2023]
Abstract
Regulation of actin dynamics is a central theme in cell biology that is important for different aspects of cell physiology. Villin, a member of the villin/gelsolin/fragmin superfamily of proteins, is an important regulator of actin. Villins contain six gelsolin homology domains (G1-G6) and an extra headpiece domain. In contrast to their mammalian counterparts, plant villins are expressed widely, implying that plant villins play a more general role in regulating actin dynamics. Some plant villins have a defined role in modifying actin dynamics in the pollen tube; most of their in vivo activities remain to be ascertained. Recently, our understanding of the functions and mechanisms of action for plant villins has progressed rapidly, primarily due to the advent of Arabidopsis thaliana genetic approaches and imaging capabilities that can visualize actin dynamics at the single filament level in vitro and in living plant cells. In this review, we focus on discussing the biochemical activities and modes of regulation of plant villins. Here, we present current understanding of the functions of plant villins. Finally, we highlight some of the key unanswered questions regarding the functions and regulation of plant villins for future research.
Collapse
Affiliation(s)
- Shanjin Huang
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, the Chinese Academy of Sciences, Beijing, 100093, China
| | | | | |
Collapse
|
8
|
Wang J, Qian D, Fan T, Jia H, An L, Xiang Y. Arabidopsis actin capping protein (AtCP) subunits have different expression patterns, and downregulation of AtCPB confers increased thermotolerance of Arabidopsis after heat shock stress. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2012; 193-194:110-119. [PMID: 22794924 DOI: 10.1016/j.plantsci.2012.06.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 04/30/2012] [Accepted: 06/04/2012] [Indexed: 05/16/2023]
Abstract
As a heterodimer actin-binding protein, capping protein is composed of α and β subunits, and can stabilize the actin filament cytoskeleton by binding to F-actin ends to inhibit G-actin addition or loss from that end. Until now, studies on plant capping protein have focused on biochemical functions in vitro, and so the expression patterns and physiological functions of actin capping protein in Arabidopsis (AtCP) are poorly understood. In the present study, real-time quantitative PCR and Western blot analysis showed that although AtCP α and β subunits (i.e. AtCPA and AtCPB) were expressed in various tissues, their expression patterns were significantly different. GUS staining further indicated they were present in different parts of the same organs. We also demonstrated that the expression levels of both subunits were induced by heat shock stress. However, only the atcpβ-mutant showed enhanced thermotolerance, and confocal microscopy showed that the actin filaments of the atcpβ-mutant were much more complete than that in the wild-type and the atcpα-mutant after heat treatment at 45 °C for 40 and 45 min. In conclusion, these results demonstrated that AtCPA and AtCPB showed distinct expression patterns in vivo, and that downregulation of AtCPB conferred increased plant thermotolerance after heat shock stress.
Collapse
Affiliation(s)
- Jue Wang
- Key Laboratory of Arid and Grassland Agroecology of Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.
| | - Dong Qian
- Key Laboratory of Arid and Grassland Agroecology of Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Tingting Fan
- Key Laboratory of Arid and Grassland Agroecology of Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Honglei Jia
- Key Laboratory of Arid and Grassland Agroecology of Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou 730000, China
| | - Lizhe An
- Key Laboratory of Arid and Grassland Agroecology of Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.
| | - Yun Xiang
- Key Laboratory of Arid and Grassland Agroecology of Ministry of Education, School of Life Sciences, Lanzhou University, Lanzhou 730000, China.
| |
Collapse
|
9
|
Xue XH, Guo CQ, Du F, Lu QL, Zhang CM, Ren HY. AtFH8 is involved in root development under effect of low-dose latrunculin B in dividing cells. MOLECULAR PLANT 2011; 4:264-78. [PMID: 21307369 DOI: 10.1093/mp/ssq085] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Formins have been paid much attention for their potent nucleating activity. However, the connection between the in vivo functions of AtFHs (Arabidopsis thaliana formin homologs) and their effects on actin organization is poorly understood. In this study, we characterized the bundling activity of AtFH8 in vitro and in vivo. Biochemical analysis showed that AtFH8(FH1FH2) could form dimers and bundle preformed actin filaments or induce stellar structures during actin polymerization. Expression of truncated forms of AtFH8 and immunolocalization analysis showed that AtFH8 localized primarily to nuclear envelope in interphase and to the new cell wall after cytokinesis, depending primarily on its N-terminal transmembrane domain. GUS histochemical staining showed AtFH8 was predominantly expressed in Arabidopsis root meristem, vasculature, and outgrowth points of lateral roots. The primary root growth and lateral root initiation of atfh8 could be decreased by latrunculin B (LatB). Analysis of the number of dividing cells in Arabidopsis root tips showed that much fewer dividing cells in Lat B-treated atfh8 plants than wild-type plants, which indicates that AtFH8 was involved in cell division. Actin cytoskeleton in root meristem of atfh8-1 was more sensitive to LatB treatment than that of wild-type. Altogether, our results indicate that AtFH8 is an actin filament nucleator and bundler that functions in cell division and root development.
Collapse
Affiliation(s)
- Xiu-Hua Xue
- Key Laboratory of Cell Proliferation and Regulation Biology of Ministry of Education, College of Life Science, Beijing Normal University, Beijing 100875, China
| | | | | | | | | | | |
Collapse
|
10
|
|
11
|
|
12
|
Khurana P, Henty JL, Huang S, Staiger AM, Blanchoin L, Staiger CJ. Arabidopsis VILLIN1 and VILLIN3 have overlapping and distinct activities in actin bundle formation and turnover. THE PLANT CELL 2010; 22:2727-48. [PMID: 20807878 PMCID: PMC2947172 DOI: 10.1105/tpc.110.076240] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2010] [Revised: 07/29/2010] [Accepted: 08/17/2010] [Indexed: 05/20/2023]
Abstract
Actin filament bundles are higher-order cytoskeletal structures that are crucial for the maintenance of cellular architecture and cell expansion. They are generated from individual actin filaments by the actions of bundling proteins like fimbrins, LIMs, and villins. However, the molecular mechanisms of dynamic bundle formation and turnover are largely unknown. Villins belong to the villin/gelsolin/fragmin superfamily and comprise at least five isovariants in Arabidopsis thaliana. Different combinations of villin isovariants are coexpressed in various tissues and cells. It is not clear whether these isovariants function together and act redundantly or whether they have unique activities. VILLIN1 (VLN1) is a simple filament-bundling protein and is Ca(2+) insensitive. Based on phylogenetic analyses and conservation of Ca(2+) binding sites, we predict that VLN3 is a Ca(2+)-regulated villin capable of severing actin filaments and contributing to bundle turnover. The bundling activity of both isovariants was observed directly with time-lapse imaging and total internal reflection fluorescence (TIRF) microscopy in vitro, and the mechanism mimics the "catch and zipper" action observed in vivo. Using time-lapse TIRF microscopy, we observed and quantified the severing of individual actin filaments by VLN3 at physiological calcium concentrations. Moreover, VLN3 can sever actin filament bundles in the presence of VLN1 when calcium is elevated to micromolar levels. Collectively, these results demonstrate that two villin isovariants have overlapping and distinct activities.
Collapse
Affiliation(s)
- Parul Khurana
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-2064
| | - Jessica L. Henty
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-2064
| | - Shanjin Huang
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-2064
| | - Andrew M. Staiger
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-2064
| | - Laurent Blanchoin
- Institut de Recherches en Technologie et Sciences pour le Vivant, Commissariat à l'Energie Atomique/Centre National de la Recherche Scientifique/Institut National de la Recherche Agronomique/Université Joseph Fourier, Commissariat à l’Energie Atomique Grenoble, F38054 Grenoble, France
| | - Christopher J. Staiger
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907-2064
- The Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907
- Address correspondence to
| |
Collapse
|
13
|
Staiger CJ, Poulter NS, Henty JL, Franklin-Tong VE, Blanchoin L. Regulation of actin dynamics by actin-binding proteins in pollen. JOURNAL OF EXPERIMENTAL BOTANY 2010; 61:1969-86. [PMID: 20159884 DOI: 10.1093/jxb/erq012] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
A dynamic network of polymers, the actin cytoskeleton, co-ordinates numerous fundamental cellular processes. In pollen tubes, organelle movements and cytoplasmic streaming, organization of the tip zone, vesicle trafficking, and tip growth have all been linked to actin-based function. Further, during the self-incompatibility response of Papaver rhoeas, destruction of the cytoskeleton is a primary target implicated in the rapid cessation of pollen tube growth and alterations in actin dynamics are associated with the initiation of programmed cell death. Surprisingly, these diverse cellular processes are accomplished with only a small amount of filamentous actin and a huge pool of polymerizable monomers. These observations hint at incredibly fast and complex actin dynamics in pollen. To understand the molecular mechanisms regulating actin dynamics in plant cells, the abundant actin monomer-binding proteins, a major filament nucleator, a family of bundling and severing proteins, and a modulator of growth at the barbed-end of actin filaments have been characterized biochemically. The activities of these proteins are generally consistent with textbook models for actin turnover. For example, the three monomer-binding proteins, profilin, ADF, and CAP, are thought to function synergistically to enhance turnover and the exchange of subunits between monomer and polymer pools. How individual actin filaments behave in living cells, however, remains largely unexplored. Actin dynamics were examined using variable angle epifluorescence microscopy (VAEM) in expanding hypocotyl epidermal cells. Our observations of single filament behaviour are not consistent with filament turnover by treadmilling, but rather represent a novel property called stochastic dynamics. A new model for the dynamic control of actin filament turnover in plant cells is presented.
Collapse
Affiliation(s)
- Christopher J Staiger
- Department of Biological Sciences and Bindley Bioscience Center, Purdue University, West Lafayette, IN 47907-2064, USA.
| | | | | | | | | |
Collapse
|