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Li X, Bruckmann A, Dresselhaus T, Begcy K. Heat stress at the bicellular stage inhibits sperm cell development and transport into pollen tubes. PLANT PHYSIOLOGY 2024; 195:2111-2128. [PMID: 38366643 PMCID: PMC11213256 DOI: 10.1093/plphys/kiae087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 01/18/2024] [Accepted: 01/23/2024] [Indexed: 02/18/2024]
Abstract
For successful double fertilization in flowering plants (angiosperms), pollen tubes deliver 2 nonmotile sperm cells toward female gametes (egg and central cell, respectively). Heatwaves, especially during the reproduction period, threaten male gametophyte (pollen) development, resulting in severe yield losses. Using maize (Zea mays) as a crop and grass model system, we found strong seed set reduction when moderate heat stress was applied for 2 d during the uni- and bicellular stages of pollen development. We show that heat stress accelerates pollen development and impairs pollen germination capabilities when applied at the unicellular stage. Heat stress at the bicellular stage impairs sperm cell development and transport into pollen tubes. To understand the course of the latter defects, we used marker lines and analyzed the transcriptomes of isolated sperm cells. Heat stress affected the expression of genes associated with transcription, RNA processing and translation, DNA replication, and the cell cycle. This included the genes encoding centromeric histone 3 (CENH3) and α-tubulin. Most genes that were misregulated encode proteins involved in the transition from metaphase to anaphase during pollen mitosis II. Heat stress also activated spindle assembly check point and meta- to anaphase transition genes in sperm cells. In summary, misregulation of the identified genes during heat stress at the bicellular stage results in sperm cell development and transport defects ultimately leading to sterility.
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Affiliation(s)
- Xingli Li
- Department of Cell Biology and Plant Biochemistry, University of Regensburg, 93053 Regensburg, Germany
| | - Astrid Bruckmann
- Department for Biochemistry I, Biochemistry Centre, University of Regensburg, 93053 Regensburg, Germany
| | - Thomas Dresselhaus
- Department of Cell Biology and Plant Biochemistry, University of Regensburg, 93053 Regensburg, Germany
| | - Kevin Begcy
- Environmental Horticulture Department, University of Florida, Gainesville, FL32611, USA
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2
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Iqbal A, Aslam S, Ahmed M, Khan F, Ali Q, Han S. Role of Actin Dynamics and GhACTIN1 Gene in Cotton Fiber Development: A Prototypical Cell for Study. Genes (Basel) 2023; 14:1642. [PMID: 37628693 PMCID: PMC10454433 DOI: 10.3390/genes14081642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Revised: 08/13/2023] [Accepted: 08/15/2023] [Indexed: 08/27/2023] Open
Abstract
Cotton crop is considered valuable for its fiber and seed oil. Cotton fiber is a single-celled outgrowth from the ovule epidermis, and it is a very dynamic cell for study. It has four distinct but overlapping developmental stages: initiation, elongation, secondary cell wall synthesis, and maturation. Among the various qualitative characteristics of cotton fiber, the important ones are the cotton fiber staple length, tensile strength, micronaire values, and fiber maturity. Actin dynamics are known to play an important role in fiber elongation and maturation. The current review gives an insight into the cotton fiber developmental stages, the qualitative traits associated with cotton fiber, and the set of genes involved in regulating these developmental stages and fiber traits. This review also highlights some prospects for how biotechnological approaches can improve cotton fiber quality.
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Affiliation(s)
- Adnan Iqbal
- School of Biological Sciences and Technology, Liupanshui Normal University, Liupanshui 553004, China;
- Plant Breeding and Acclimatization Institute—National Research Institute, Radzikow, 05-870 Blonie, Poland
| | - Sibgha Aslam
- Plant Breeding and Acclimatization Institute—National Research Institute, Radzikow, 05-870 Blonie, Poland
| | - Mukhtar Ahmed
- Government Boys College Sokasan, Higher Education Department, Azad Jammu and Kashmir, Bhimber 10040, Pakistan
| | - Fahad Khan
- Department of Plant Protection, Faculty of Agricultural Sciences, Ghazi University, Dera Ghazi Khan 33001, Pakistan
| | - Qurban Ali
- Department of Plant Breeding and Genetics, Faculty of Agricultural Sciences, University of the Punjab, Lahore 54590, Pakistan
| | - Shiming Han
- School of Biological Sciences and Technology, Liupanshui Normal University, Liupanshui 553004, China;
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3
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Chen J, Pan B, Li Z, Xu Y, Cao X, Jia J, Shen H, Sun L. Fruit shape loci sun, ovate, fs8.1 and their interactions affect seed size and shape in tomato. FRONTIERS IN PLANT SCIENCE 2023; 13:1091639. [PMID: 36714752 PMCID: PMC9879704 DOI: 10.3389/fpls.2022.1091639] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Accepted: 12/22/2022] [Indexed: 06/18/2023]
Abstract
Seed size and shape are not only critical for plant reproduction and dispersal, but also important agronomic traits. Tomato fruit shape loci sun, ovate and fs8.1 regulate the morphology of fruit, flower, leaf and stem, and recently their functions in seed morphogenesis have also been noticed. However, mechanism underlying seed morphology variation has not been systematically investigated yet. Thus, using the near isogenic lines (NILs) harboring one, two or three of the fruit shape loci, histological, physiological and transcriptional bases of seed morphology change have been studied. sun and ovate showed potential abilities in decreasing seed size, whereas, fs8.1 had a potential ability in increasing this parameter. Interactions between two loci and the interaction among three loci all led to significant decrease of seed size. All the loci significantly down-regulated seed shape index (SSI), except for sun/fs8.1 double NIL, which resulted in the reductions in both seed length and width and finally led to a decreased trend of SSI. Histologically, seed morphological changes were mainly attributed to the cell number variations. Transcriptional and physiological analyses discovered that phytohormone-, cytoskeleton- as well as sugar transportation- and degradation-related genes were involved in the regulation of seed morphology by the fruit shape loci.
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Affiliation(s)
- Jie Chen
- College of Horticulture, China Agricultural University, Beijing, China
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing, China
| | - Bingqing Pan
- College of Horticulture, China Agricultural University, Beijing, China
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing, China
| | - Zixiong Li
- College of Horticulture, China Agricultural University, Beijing, China
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing, China
| | - Yue Xu
- College of Horticulture, China Agricultural University, Beijing, China
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing, China
| | - Xiaomeng Cao
- College of Horticulture, China Agricultural University, Beijing, China
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing, China
| | - Jingjing Jia
- College of Horticulture, China Agricultural University, Beijing, China
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing, China
| | - Huolin Shen
- College of Horticulture, China Agricultural University, Beijing, China
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing, China
| | - Liang Sun
- College of Horticulture, China Agricultural University, Beijing, China
- Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University, Beijing, China
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4
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Fisher LAB, Schöck F. The unexpected versatility of ALP/Enigma family proteins. Front Cell Dev Biol 2022; 10:963608. [PMID: 36531944 PMCID: PMC9751615 DOI: 10.3389/fcell.2022.963608] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 11/22/2022] [Indexed: 12/04/2022] Open
Abstract
One of the most intriguing features of multicellular animals is their ability to move. On a cellular level, this is accomplished by the rearrangement and reorganization of the cytoskeleton, a dynamic network of filamentous proteins which provides stability and structure in a stationary context, but also facilitates directed movement by contracting. The ALP/Enigma family proteins are a diverse group of docking proteins found in numerous cellular milieus and facilitate these processes among others. In vertebrates, they are characterized by having a PDZ domain in combination with one or three LIM domains. The family is comprised of CLP-36 (PDLIM1), Mystique (PDLIM2), ALP (PDLIM3), RIL (PDLIM4), ENH (PDLIM5), ZASP (PDLIM6), and Enigma (PDLIM7). In this review, we will outline the evolution and function of their protein domains which confers their versatility. Additionally, we highlight their role in different cellular environments, focusing specifically on recent advances in muscle research using Drosophila as a model organism. Finally, we show the relevance of this protein family to human myopathies and the development of muscle-related diseases.
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5
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Zhang R, Qu X, Zhang M, Jiang Y, Dai A, Zhao W, Cao D, Lan Y, Yu R, Wang H, Huang S. The Balance between Actin-Bundling Factors Controls Actin Architecture in Pollen Tubes. iScience 2019; 16:162-176. [PMID: 31181400 PMCID: PMC6556835 DOI: 10.1016/j.isci.2019.05.026] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 04/29/2019] [Accepted: 05/21/2019] [Indexed: 11/19/2022] Open
Abstract
How actin-bundling factors cooperatively regulate shank-localized actin bundles remains largely unexplored. Here we demonstrate that FIM5 and PLIM2a/PLIM2b decorate shank-localized actin bundles and that loss of function of PLIM2a and/or PLIM2b suppresses phenotypes associated with fim5 mutants. Specifically, knockout of PLIM2a and/or PLIM2b partially suppresses the disorganized actin bundle and intracellular trafficking phenotype in fim5 pollen tubes. PLIM2a/PLIM2b generates thick but loosely packed actin bundles, whereas FIM5 generates thin but tight actin bundles that tend to be cross-linked into networks in vitro. Furthermore, PLIM2a/PLIM2b and FIM5 compete for binding to actin filaments in vitro, and PLIM2a/PLIM2b decorate disorganized actin bundles in fim5 pollen tubes. These data together suggest that the disorganized actin bundles in fim5 mutants are at least partially due to gain of function of PLIM2a/PLIM2b. Our data suggest that the balance between FIM5 and PLIM2a/PLIM2b is crucial for the normal bundling and organization of shank-localized actin bundles in pollen tubes. The transcription of PLIM2a and PLIM2b is upregulated in fim5 pollen tubes Downregulation of PLIM2a and/or PLIM2b suppresses the defects in fim5 pollen tubes Both FIM5 and PLIM2a/PLIM2b decorate shank-localized actin filaments FIM5 can inhibit the binding of PLIM2a and PLIM2b to actin filaments
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Affiliation(s)
- Ruihui Zhang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Xiaolu Qu
- 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
| | - Yuxiang Jiang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Anbang Dai
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Wanying Zhao
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Dai Cao
- School of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Yaxian Lan
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Rong Yu
- School of Life Sciences, Capital Normal University, Beijing 100048, China
| | - Hongwei Wang
- Ministry of Education Key Laboratory of Protein Sciences, Tsinghua-Peking Joint Center for Life Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Shanjin Huang
- Center for Plant Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China.
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6
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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: 30] [Impact Index Per Article: 6.0] [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.
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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.
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7
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Du TT, Dewey JB, Wagner EL, Cui R, Heo J, Park JJ, Francis SP, Perez-Reyes E, Guillot SJ, Sherman NE, Xu W, Oghalai JS, Kachar B, Shin JB. LMO7 deficiency reveals the significance of the cuticular plate for hearing function. Nat Commun 2019; 10:1117. [PMID: 30850599 PMCID: PMC6408450 DOI: 10.1038/s41467-019-09074-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Accepted: 02/15/2019] [Indexed: 12/25/2022] Open
Abstract
Sensory hair cells, the mechanoreceptors of the auditory and vestibular systems, harbor two specialized elaborations of the apical surface, the hair bundle and the cuticular plate. In contrast to the extensively studied mechanosensory hair bundle, the cuticular plate is not as well understood. It is believed to provide a rigid foundation for stereocilia motion, but specifics about its function, especially the significance of its integrity for long-term maintenance of hair cell mechanotransduction, are not known. We discovered that a hair cell protein called LIM only protein 7 (LMO7) is specifically localized in the cuticular plate and the cell junction. Lmo7 KO mice suffer multiple cuticular plate deficiencies, including reduced filamentous actin density and abnormal stereociliar rootlets. In addition to the cuticular plate defects, older Lmo7 KO mice develop abnormalities in inner hair cell stereocilia. Together, these defects affect cochlear tuning and sensitivity and give rise to late-onset progressive hearing loss.
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MESH Headings
- Actins/metabolism
- Animals
- Cochlea/physiology
- Disease Models, Animal
- Hair Cells, Auditory/physiology
- Hair Cells, Auditory/ultrastructure
- Hair Cells, Auditory, Inner/physiology
- Hair Cells, Auditory, Inner/ultrastructure
- Hearing/genetics
- Hearing/physiology
- Hearing Loss/etiology
- Hearing Loss/genetics
- Hearing Loss/physiopathology
- LIM Domain Proteins/deficiency
- LIM Domain Proteins/genetics
- LIM Domain Proteins/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Inbred CBA
- Mice, Knockout
- Microscopy, Electron, Scanning
- Stereocilia/genetics
- Stereocilia/physiology
- Stereocilia/ultrastructure
- Transcription Factors/deficiency
- Transcription Factors/genetics
- Transcription Factors/physiology
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Affiliation(s)
- Ting-Ting Du
- Department of Neuroscience, University of Virginia, Charlottesville, VA, 22908, USA
| | - James B Dewey
- Caruso Department of Otolaryngology-Head and Neck Surgery, University of Southern California, Los Angeles, CA, 90033, USA
| | - Elizabeth L Wagner
- Department of Neuroscience, University of Virginia, Charlottesville, VA, 22908, USA
| | - Runjia Cui
- National Institute for Deafness and Communications Disorders, National Institute of Health, Bethesda, MD, 20892, USA
| | - Jinho Heo
- Center for Cell Signaling and Department of Microbiology, Immunology and Cancer Biology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Jeong-Jin Park
- Biomolecular Analysis Facility, University of Virginia, Charlottesville, VA, 22908, USA
| | - Shimon P Francis
- Department of Neuroscience, University of Virginia, Charlottesville, VA, 22908, USA
| | - Edward Perez-Reyes
- Department of Pharmacology, University of Virginia, Charlottesville, VA, 22908, USA
| | - Stacey J Guillot
- Advanced Microscopy core, University of Virginia, Charlottesville, VA, 22908, USA
| | - Nicholas E Sherman
- Biomolecular Analysis Facility, University of Virginia, Charlottesville, VA, 22908, USA
| | - Wenhao Xu
- Genetically Engineered Murine Model (GEMM) core, University of Virginia, Charlottesville, VA, 22908, USA
| | - John S Oghalai
- Caruso Department of Otolaryngology-Head and Neck Surgery, University of Southern California, Los Angeles, CA, 90033, USA
| | - Bechara Kachar
- National Institute for Deafness and Communications Disorders, National Institute of Health, Bethesda, MD, 20892, USA
| | - Jung-Bum Shin
- Department of Neuroscience, University of Virginia, Charlottesville, VA, 22908, USA.
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8
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Zhang S, Wang C, Xie M, Liu J, Kong Z, Su H. Actin Bundles in The Pollen Tube. Int J Mol Sci 2018; 19:ijms19123710. [PMID: 30469514 PMCID: PMC6321563 DOI: 10.3390/ijms19123710] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 11/18/2018] [Accepted: 11/19/2018] [Indexed: 12/31/2022] Open
Abstract
The angiosperm pollen tube delivers two sperm cells into the embryo sac through a unique growth strategy, named tip growth, to accomplish fertilization. A great deal of experiments have demonstrated that actin bundles play a pivotal role in pollen tube tip growth. There are two distinct actin bundle populations in pollen tubes: the long, rather thick actin bundles in the shank and the short, highly dynamic bundles near the apex. With the development of imaging techniques over the last decade, great breakthroughs have been made in understanding the function of actin bundles in pollen tubes, especially short subapical actin bundles. Here, we tried to draw an overall picture of the architecture, functions and underlying regulation mechanism of actin bundles in plant pollen tubes.
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Affiliation(s)
- Shujuan Zhang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Chunbo Wang
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Min Xie
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Jinyu Liu
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Zhe Kong
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
| | - Hui Su
- Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education College of Life Science, Northwest University, Xi'an 710069, China.
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9
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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.
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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.
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10
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Han L, Li Y, Sun Y, Wang H, Kong Z, Xia G. The two domains of cotton WLIM1a protein are functionally divergent. SCIENCE CHINA-LIFE SCIENCES 2016; 59:206-12. [PMID: 26803305 DOI: 10.1007/s11427-016-5002-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 07/20/2015] [Indexed: 01/27/2023]
Affiliation(s)
- Libo Han
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China.
| | - Yuanbao Li
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yongduo Sun
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
- College of Life Sciences, University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Haiyun Wang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Zhaosheng Kong
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Guixian Xia
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100101, China
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11
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Srivastava V, Verma PK. Genome Wide Identification of LIM Genes in Cicer arietinum and Response of Ca-2LIMs in Development, Hormone and Pathogenic Stress. PLoS One 2015; 10:e0138719. [PMID: 26418014 PMCID: PMC4587737 DOI: 10.1371/journal.pone.0138719] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2015] [Accepted: 09/02/2015] [Indexed: 11/20/2022] Open
Abstract
The eukaryotic lineage-specific LIM protein (LIN11, ISL1, and MEC3) family play pivotal role in modulation of actin dynamics and transcriptional regulation. The systematic investigation of this family has not been carried in detail and rare in legumes. Current study involves the mining of Cicer arietinum genome for the genes coding for LIM domain proteins and displayed significant homology with LIM genes of other species. The analysis led to the identification of 15 members, which were positioned on chickpea chromosomes. The phylogenetic and motif analysis suggested their categorization into two sub-families i.e., Ca-2LIMs and Ca-DA1/DAR, which comprised of nine and six candidates, respectively. Further sub-categories of Ca-2LIMs were recognised as αLIM, βLIM, δLIM and γLIM. The LIM genes within their sub-families displayed conserved genomic and motif organization. The expression pattern of Ca-2LIMs across developmental and reproductive tissues demonstrated strong correlation with established consensus. The Ca-2LIM belongs to PLIM and GLIM (XLIM) was found highly expressed in floral tissue. Others showed ubiquitous expression pattern with their dominance in stem. Under hormonal and pathogenic conditions these LIMs were found to up-regulate during salicylic acid, abscisic acid and Ascochyta rabiei treatment or infection; and down-regulated in response to jasmonic acid treatment. The findings of this work, particularly in terms of modulation of LIM genes under biotic stress will open up the way to further explore and establish the role of chickpea LIMs in plant defense response.
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Affiliation(s)
- Vikas Srivastava
- Plant Immunity Laboratory, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India
| | - Praveen Kumar Verma
- Plant Immunity Laboratory, National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India
- * E-mail:
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12
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Moes D, Hoffmann C, Dieterle M, Moreau F, Neumann K, Papuga J, Furtado AT, Steinmetz A, Thomas C. The pH sensibility of actin-bundling LIM proteins is governed by the acidic properties of their C-terminal domain. FEBS Lett 2015; 589:2312-9. [PMID: 26226417 DOI: 10.1016/j.febslet.2015.07.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/17/2015] [Accepted: 07/17/2015] [Indexed: 11/22/2022]
Abstract
Actin-bundling Arabidopsis LIM proteins are subdivided into two subfamilies differing in their pH sensitivity. Widely-expressed WLIMs are active under low and high physiologically-relevant pH conditions, whereas pollen-enriched PLIMs are inactivated by pH values above 6.8. By a domain swapping approach we identified the C-terminal (Ct) domain of PLIMs as the domain responsible for pH responsiveness. Remarkably, this domain conferred pH sensitivity to LIM proteins, when provided "in trans" (i.e., as a single, independent, peptide), indicating that it operates through the interaction with another domain. An acidic 6xc-Myc peptide functionally mimicked the Ct domain of PLIMs and efficiently inhibited LIM actin bundling activity under high pH conditions. Together, our data suggest a model where PLIMs are regulated by an intermolecular interaction between their acidic Ct domain and another, yet unidentified, domain.
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Affiliation(s)
- Danièle Moes
- Department of Oncology, Luxembourg Institute of Health (L.I.H.), L-1526 Luxembourg, Luxembourg
| | - Céline Hoffmann
- Department of Oncology, Luxembourg Institute of Health (L.I.H.), L-1526 Luxembourg, Luxembourg
| | - Monika Dieterle
- Department of Oncology, Luxembourg Institute of Health (L.I.H.), L-1526 Luxembourg, Luxembourg
| | - Flora Moreau
- Department of Oncology, Luxembourg Institute of Health (L.I.H.), L-1526 Luxembourg, Luxembourg
| | - Katrin Neumann
- Department of Oncology, Luxembourg Institute of Health (L.I.H.), L-1526 Luxembourg, Luxembourg
| | - Jessica Papuga
- Department of Oncology, Luxembourg Institute of Health (L.I.H.), L-1526 Luxembourg, Luxembourg
| | - Angela Tavares Furtado
- Department of Oncology, Luxembourg Institute of Health (L.I.H.), L-1526 Luxembourg, Luxembourg
| | - André Steinmetz
- Department of Oncology, Luxembourg Institute of Health (L.I.H.), L-1526 Luxembourg, Luxembourg
| | - Clément Thomas
- Department of Oncology, Luxembourg Institute of Health (L.I.H.), L-1526 Luxembourg, Luxembourg.
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13
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Li L, Li Y, Wang NN, Li Y, Lu R, Li XB. Cotton LIM domain-containing protein GhPLIM1 is specifically expressed in anthers and participates in modulating F-actin. PLANT BIOLOGY (STUTTGART, GERMANY) 2015; 17:528-534. [PMID: 25294521 DOI: 10.1111/plb.12243] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 06/23/2014] [Indexed: 06/03/2023]
Abstract
As one form of actin binding protein (ABP), LIM domain protein can trigger the formation of actin bundles during plant growth and development. In this study, a cDNA (designated GhPLIM1) encoding a LIM domain protein with 216 amino acid residues was identified from a cotton flower cDNA library. Quantitative RT-PCR indicated that GhPLIM1 is specifically expressed in cotton anthers, and its expression levels are regulated during anther development of cotton. GhPLIM1:eGFP transformed cotton cells display a distributed network of eGFP fluorescence, suggesting that GhPLIM1 protein is mainly localised to the cell cytoskeleton. In vitro high-speed co-sedimentation and low co-sedimentation assays indicate that GhPLIM1 protein not only directly binds actin filaments but also bundles F-actin. Further biochemical experiments verified that GhPLIM1 protein can protect F-actin against depolymerisation by Lat B. Thus, our data demonstrate that GhPLIM1 functions as an actin binding protein (ABP) in modulating actin filaments in vitro, suggesting that GhPLIM1 may be involved in regulating the actin cytoskeleton required for pollen development in cotton.
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Affiliation(s)
- L Li
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
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14
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Hoffmann C, Moes D, Dieterle M, Neumann K, Moreau F, Tavares Furtado A, Dumas D, Steinmetz A, Thomas C. Live cell imaging reveals actin-cytoskeleton-induced self-association of the actin-bundling protein WLIM1. J Cell Sci 2014; 127:583-98. [PMID: 24284066 DOI: 10.1242/jcs.134536] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Crosslinking of actin filaments into bundles is essential for the assembly and stabilization of specific cytoskeletal structures. However, relatively little is known about the molecular mechanisms underlying actin bundle formation. The two LIM-domain-containing proteins define a novel and evolutionarily conserved family of actin-bundling proteins whose actin-binding and -crosslinking activities primarily rely on their LIM domains. Using TIRF microscopy, we describe real-time formation of actin bundles induced by tobacco NtWLIM1 in vitro. We show that NtWLIM1 binds to single filaments and subsequently promotes their interaction and zippering into tight bundles of mixed polarity. NtWLIM1-induced bundles grew by both elongation of internal filaments and addition of preformed fragments at their extremities. Importantly, these data are highly consistent with the modes of bundle formation and growth observed in transgenic Arabidopsis plants expressing a GFP-fused Arabidopsis AtWLIM1 protein. Using two complementary live cell imaging approaches, a close relationship between NtWLIM1 subcellular localization and self-association was established. Indeed, both BiFC and FLIM-FRET data revealed that, although unstable NtWLIM1 complexes can sporadically form in the cytosol, stable complexes concentrate along the actin cytoskeleton. Remarkably, disruption of the actin cytoskeleton significantly impaired self-association of NtWLIM1. In addition, biochemical analyses support the idea that F-actin facilitates the switch of purified recombinant NtWLIM1 from a monomeric to a di- or oligomeric state. On the basis of our data, we propose a model in which actin binding promotes the formation and stabilization of NtWLIM1 complexes, which in turn might drive the crosslinking of actin filaments.
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Affiliation(s)
- Céline Hoffmann
- Centre de Recherche Public-Santé, 84 Val Fleuri, L-1526 Luxembourg, Luxembourg
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15
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Clark KA, Kadrmas JL. Drosophila melanogaster muscle LIM protein and alpha-actinin function together to stabilize muscle cytoarchitecture: a potential role for Mlp84B in actin-crosslinking. Cytoskeleton (Hoboken) 2013; 70:304-16. [PMID: 23606669 PMCID: PMC3716849 DOI: 10.1002/cm.21106] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 03/04/2013] [Accepted: 03/06/2013] [Indexed: 02/06/2023]
Abstract
Stabilization of tissue architecture during development and growth is essential to maintain structural integrity. Because of its contractile nature, muscle is especially susceptible to physiological stresses, and has multiple mechanisms to maintain structural integrity. The Drosophila melanogaster Muscle LIM Protein (MLP), Mlp84B, participates in muscle maintenance, yet its precise mechanism of action is still controversial. Through a candidate approach, we identified α-actinin as a protein that functions with Mlp84B to ensure muscle integrity. α-actinin RNAi animals die primarily as pupae, and Mlp84B RNAi animals are adult viable. RNAi knockdown of Mlp84B and α-actinin together produces synergistic early larval lethality and destabilization of Z-line structures. We recapitulated these phenotypes using combinations of traditional loss-of-function alleles and single-gene RNAi. We observe that Mlp84B induces the formation of actin loops in muscle cell nuclei in the absence of nuclear α-actinin, suggesting Mlp84B has intrinsic actin cross-linking activity, which may complement α-actinin cross-linking activity at sites of actin filament anchorage. These results reveal a molecular mechanism for MLP stabilization of muscle and implicate reduced actin crosslinking as the primary destabilizing defect in MLP-associated cardiomyopathies. Our data support a model in which α-actinin and Mlp84B have important and overlapping functions at sites of actin filament anchorage to preserve muscle structure and function.
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Affiliation(s)
- Kathleen A. Clark
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112
- Department of Biology, University of Utah, Salt Lake City, UT 84112
- Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112
| | - Julie L. Kadrmas
- Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112
- Department of Oncological Sciences, University of Utah, Salt Lake City, UT 84112
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16
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Li Y, Jiang J, Li L, Wang XL, Wang NN, Li DD, Li XB. A cotton LIM domain-containing protein (GhWLIM5) is involved in bundling actin filaments. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2013; 66:34-40. [PMID: 23466745 DOI: 10.1016/j.plaphy.2013.01.018] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Accepted: 01/18/2013] [Indexed: 06/01/2023]
Abstract
LIM-domain proteins play important roles in cellular processes in eukaryotes. In this study, a LIM protein gene, GhWLIM5, was identified in cotton. Quantitative RT-PCR analysis showed that GhWLIM5 was expressed widely in different cotton tissues and had a peak in expression during fiber elongation. GFP fluorescence assay revealed that cotton cells expressing GhWLIM5:eGFP fusion gene displayed a network distribution of eGFP fluorescence, suggesting that GhWLIM5 protein is mainly localized to the cell cytoskeleton. When GhWLIM5:eGFP transformed cells were stained with rhodamine-phalloidin there was consistent overlap in eGFP and rhodamine-palloidin signals, demonstrating that GhWLIM5 protein is colocalized with the F-actin cytoskeleton. In addition, high-speed cosedimentation assay verified that GhWLIM5 directly bound actin filaments, while low cosedimentation assay and microscopic observation indicated that GhWLIM5 bundled F-actin in vitro. Increasing amounts of GhWLIM5 protein were able to protect F-actin from depolymerization in vitro in the presence of Lat B (an F-actin depolymerizer). Our results contribute to a better understanding of the biochemical role of GhWLIM5 in modulating the dynamic F-actin network in cotton.
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Affiliation(s)
- Yang Li
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, College of Life Sciences, Central China Normal University, Wuhan 430079, China
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17
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Zaban B, Maisch J, Nick P. Dynamic actin controls polarity induction de novo in protoplasts. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2013; 55:142-59. [PMID: 23127141 DOI: 10.1111/jipb.12001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Cell polarity and axes are central for plant morphogenesis. To study how polarity and axes are induced de novo, we investigated protoplasts of tobacco Nicotiana tabacum cv. BY-2 expressing fluorescently-tagged cytoskeletal markers. We standardized the system to such a degree that we were able to generate quantitative data on the temporal patterns of regeneration stages. The synthesis of a new cell wall marks the transition to the first stage of regeneration, and proceeds after a long preparatory phase within a few minutes. During this preparatory phase, the nucleus migrates actively, and cytoplasmic strands remodel vigorously. We probed this system for the effect of anti-cytoskeletal compounds, inducible bundling of actin, RGD-peptides, and temperature. Suppression of actin dynamics at an early stage leads to aberrant tripolar cells, whereas suppression of microtubule dynamics produces aberrant sausage-like cells with asymmetric cell walls. We integrated these data into a model, where the microtubular cytoskeleton conveys positional information between the nucleus and the membrane controlling the release or activation of components required for cell wall synthesis. Cell wall formation is followed by the induction of a new cell pole requiring dynamic actin filaments, and the new cell axis is manifested as elongation growth perpendicular to the orientation of the aligned cortical microtubules.
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Affiliation(s)
- Beatrix Zaban
- Botanical Institute, Molecular Cell Biology, Karlsruhe Institute of Technology, Kaiserstr. 2, D-76128 Karlsruhe, Germany.
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18
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Thomas C. Bundling actin filaments from membranes: some novel players. FRONTIERS IN PLANT SCIENCE 2012; 3:188. [PMID: 22936939 PMCID: PMC3426786 DOI: 10.3389/fpls.2012.00188] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2012] [Accepted: 08/01/2012] [Indexed: 05/04/2023]
Abstract
Progress in live-cell imaging of the cytoskeleton has significantly extended our knowledge about the organization and dynamics of actin filaments near the plasma membrane of plant cells. Noticeably, two populations of filamentous structures can be distinguished. On the one hand, fine actin filaments which exhibit an extremely dynamic behavior basically characterized by fast polymerization and prolific severing events, a process referred to as actin stochastic dynamics. On the other hand, thick actin bundles which are composed of several filaments and which are comparatively more stable although they constantly remodel as well. There is evidence that the actin cytoskeleton plays critical roles in trafficking and signaling at both the cell cortex and organelle periphery but the exact contribution of actin bundles remains unclear. A common view is that actin bundles provide the long-distance tracks used by myosin motors to deliver their cargo to growing regions and accordingly play a particularly important role in cell polarization. However, several studies support that actin bundles are more than simple passive highways and display multiple and dynamic roles in the regulation of many processes, such as cell elongation, polar auxin transport, stomatal and chloroplast movement, and defense against pathogens. The list of identified plant actin-bundling proteins is ever expanding, supporting that plant cells shape structurally and functionally different actin bundles. Here I review the most recently characterized actin-bundling proteins, with a particular focus on those potentially relevant to membrane trafficking and/or signaling.
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Affiliation(s)
- Clément Thomas
- Laboratory of Molecular and Cellular Oncology, Department of Oncology, Public Research Centre for Health (CRP-Santé)Luxembourg, Luxembourg
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19
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Ye J, Xu M. Actin bundler PLIM2s are involved in the regulation of pollen development and tube growth in Arabidopsis. JOURNAL OF PLANT PHYSIOLOGY 2012; 169:516-22. [PMID: 22209219 DOI: 10.1016/j.jplph.2011.11.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Revised: 11/23/2011] [Accepted: 11/23/2011] [Indexed: 05/21/2023]
Abstract
Microspores develop inside the anther, where they are surrounded by nourishing tapetal cells. However, many cellular processes occurring during microspore development in the locule are poorly characterized. The actin cytoskeleton is known to play a crucial role in various aspects of the plant developmental process. During pollen tube tip growth, actin cytoskeleton serves as an efficient molecular transportation track, although how it functions in pollen development is unknown. The plant actin bundler PLIM2s have been shown to regulate actin bundling in different cells. Here, we investigate the biological function of three Arabidopsis pollen-specific LIM proteins, PLIM2a, PLIM2b, and PLIM2c (collectively, PLIM2s), in pollen development and tube growth. Variable degrees of suppressed expression of the PLIM2s by RNA interference resulted in aberrant phenotypes. Complete suppression of the PLIM2s totally disrupted pollen development, producing abortive pollen grains and rendering the transgenic plants sterile. Partial suppression of the PLIM2s arrested pollen tube growth to a lesser extent, resulting in short and swollen pollen tubes. Finally, the PLIM2c promoter initiated expression in pollen during stamen filament elongation, and the PLIM2c protein was located on particle structures in the developing pollen grains in Arabidopsis. These suggest that the actin bundler, PLIM2s, are an important factor for Arabidopsis pollen development and tube growth.
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Affiliation(s)
- Jianrong Ye
- National Maize Improvement Center of China, China Agricultural University, 2 West Yuanmingyuan Road, Beijing 100193, PR China.
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20
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van der Honing HS, Kieft H, Emons AMC, Ketelaar T. Arabidopsis VILLIN2 and VILLIN3 are required for the generation of thick actin filament bundles and for directional organ growth. PLANT PHYSIOLOGY 2012; 158:1426-38. [PMID: 22209875 PMCID: PMC3291277 DOI: 10.1104/pp.111.192385] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 12/21/2011] [Indexed: 05/18/2023]
Abstract
In plant cells, actin filament bundles serve as tracks for myosin-dependent organelle movement and play a role in the organization of the cytoplasm. Although virtually all plant cells contain actin filament bundles, the role of the different actin-bundling proteins remains largely unknown. In this study, we investigated the role of the actin-bundling protein villin in Arabidopsis (Arabidopsis thaliana). We used Arabidopsis T-DNA insertion lines to generate a double mutant in which VILLIN2 (VLN2) and VLN3 transcripts are truncated. Leaves, stems, siliques, and roots of vln2 vln3 double mutant plants are twisted, which is caused by local differences in cell length. Microscopy analysis of the actin cytoskeleton showed that in these double mutant plants, thin actin filament bundles are more abundant while thick actin filament bundles are virtually absent. In contrast to full-length VLN3, truncated VLN3 lacking the headpiece region does not rescue the phenotype of the vln2 vln3 double mutant. Our results show that villin is involved in the generation of thick actin filament bundles in several cell types and suggest that these bundles are involved in the regulation of coordinated cell expansion.
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Affiliation(s)
- Hannie S. van der Honing
- Laboratory of Cell Biology, Wageningen University, 6708 PB Wageningen, The Netherlands (H.S.v.d.H., H.K., A.M.C.E., T.K.); and Department of Biomolecular Systems, Stichting voor Fundamenteel Onderzoek der Materie Institute for Atomic and Molecular Physics, 1098 SG Amsterdam, The Netherlands (A.M.C.E.)
| | - Henk Kieft
- Laboratory of Cell Biology, Wageningen University, 6708 PB Wageningen, The Netherlands (H.S.v.d.H., H.K., A.M.C.E., T.K.); and Department of Biomolecular Systems, Stichting voor Fundamenteel Onderzoek der Materie Institute for Atomic and Molecular Physics, 1098 SG Amsterdam, The Netherlands (A.M.C.E.)
| | - Anne Mie C. Emons
- Laboratory of Cell Biology, Wageningen University, 6708 PB Wageningen, The Netherlands (H.S.v.d.H., H.K., A.M.C.E., T.K.); and Department of Biomolecular Systems, Stichting voor Fundamenteel Onderzoek der Materie Institute for Atomic and Molecular Physics, 1098 SG Amsterdam, The Netherlands (A.M.C.E.)
| | - Tijs Ketelaar
- Laboratory of Cell Biology, Wageningen University, 6708 PB Wageningen, The Netherlands (H.S.v.d.H., H.K., A.M.C.E., T.K.); and Department of Biomolecular Systems, Stichting voor Fundamenteel Onderzoek der Materie Institute for Atomic and Molecular Physics, 1098 SG Amsterdam, The Netherlands (A.M.C.E.)
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21
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Zhang W, Zhao Y, Guo Y, Ye K. Plant actin-binding protein SCAB1 is dimeric actin cross-linker with atypical pleckstrin homology domain. J Biol Chem 2012; 287:11981-90. [PMID: 22356912 DOI: 10.1074/jbc.m111.338525] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
SCAB1 is a novel plant-specific actin-binding protein that binds, bundles, and stabilizes actin filaments and regulates stomatal movement. Here, we dissected the structure and function of SCAB1 by structural and biochemical approaches. We show that SCAB1 is composed of an actin-binding domain, two coiled-coil (CC) domains, and a fused immunoglobulin and pleckstrin homology (Ig-PH) domain. We determined crystal structures for the CC1 and Ig-PH domains at 1.9 and 1.7 Å resolution, respectively. The CC1 domain adopts an antiparallel helical hairpin that further dimerizes into a four-helix bundle. The CC2 domain also mediates dimerization. At least one of the coiled coils is required for actin binding, indicating that SCAB1 is a bivalent actin cross-linker. The key residues required for actin binding were identified. The PH domain lacks a canonical basic phosphoinositide-binding pocket but can bind weakly to inositol phosphates via a basic surface patch, implying the involvement of inositol signaling in SCAB1 regulation. Our results provide novel insights into the functional organization of SCAB1.
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Affiliation(s)
- Wei Zhang
- College of Biological Sciences, China Agricultural University, Beijing 10019, China
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22
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Hohenberger P, Eing C, Straessner R, Durst S, Frey W, Nick P. Plant actin controls membrane permeability. BIOCHIMICA ET BIOPHYSICA ACTA 2011; 1808:2304-12. [PMID: 21669183 DOI: 10.1016/j.bbamem.2011.05.019] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Revised: 05/26/2011] [Accepted: 05/27/2011] [Indexed: 10/18/2022]
Abstract
The biological effects of electric pulses with low rise time, high field strength, and durations in the nanosecond range (nsPEFs) have attracted considerable biotechnological and medical interest. However, the cellular mechanisms causing membrane permeabilization by nanosecond pulsed electric fields are still far from being understood. We investigated the role of actin filaments for membrane permeability in plant cells using cell lines where different degrees of actin bundling had been introduced by genetic engineering. We demonstrate that stabilization of actin increases the stability of the plasma membrane against electric permeabilization recorded by penetration of Trypan Blue into the cytoplasm. By use of a cell line expressing the actin bundling WLIM domain under control of an inducible promotor we can activate membrane stabilization by the glucocorticoid analog dexamethasone. By total internal reflection fluorescence microscopy we can visualize a subset of the cytoskeleton that is directly adjacent to the plasma membrane. We conclude that this submembrane cytoskeleton stabilizes the plasma membrane against permeabilization through electric pulses.
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Affiliation(s)
- Petra Hohenberger
- Botanical Institute, Karlsruhe Institute of Technology, Kaiserstr. 2, 76128 Karlsruhe, Germany
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23
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Zhao Y, Zhao S, Mao T, Qu X, Cao W, Zhang L, Zhang W, He L, Li S, Ren S, Zhao J, Zhu G, Huang S, Ye K, Yuan M, Guo Y. The plant-specific actin binding protein SCAB1 stabilizes actin filaments and regulates stomatal movement in Arabidopsis. THE PLANT CELL 2011; 23:2314-30. [PMID: 21719691 PMCID: PMC3160031 DOI: 10.1105/tpc.111.086546] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 05/28/2011] [Accepted: 06/10/2011] [Indexed: 05/18/2023]
Abstract
Microfilament dynamics play a critical role in regulating stomatal movement; however, the molecular mechanism underlying this process is not well understood. We report here the identification and characterization of STOMATAL CLOSURE-RELATED ACTIN BINDING PROTEIN1 (SCAB1), an Arabidopsis thaliana actin binding protein. Plants lacking SCAB1 were hypersensitive to drought stress and exhibited reduced abscisic acid-, H(2)O(2)-, and CaCl(2)-regulated stomatal movement. In vitro and in vivo analyses revealed that SCAB1 binds, stabilizes, and bundles actin filaments. SCAB1 shares sequence similarity only with plant proteins and contains a previously undiscovered actin binding domain. During stomatal closure, actin filaments switched from a radial orientation in open stomata to a longitudinal orientation in closed stomata. This switch took longer in scab1 plants than in wild-type plants and was correlated with the delay in stomatal closure seen in scab1 mutants in response to drought stress. Our results suggest that SCAB1 is required for the precise regulation of actin filament reorganization during stomatal closure.
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Affiliation(s)
- Yang Zhao
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
- National Institute of Biological Sciences, Beijing 102206, China
| | - Shuangshuang Zhao
- Key Laboratory of Plant Stress, Life Science College, Shandong Normal University, Jinan 250014, China
| | - Tonglin Mao
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Xiaolu Qu
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Wanhong Cao
- National Institute of Biological Sciences, Beijing 102206, China
| | - Li Zhang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Wei Zhang
- National Institute of Biological Sciences, Beijing 102206, China
| | - Liu He
- National Institute of Biological Sciences, Beijing 102206, China
| | - Sidi Li
- National Institute of Biological Sciences, Beijing 102206, China
| | - Sulin Ren
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Jinfeng Zhao
- National Institute of Biological Sciences, Beijing 102206, China
| | - Guoli Zhu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Shanjin Huang
- Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Keqiong Ye
- National Institute of Biological Sciences, Beijing 102206, China
| | - Ming Yuan
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
| | - Yan Guo
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China
- Address correspondence to
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24
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Tang Z, Zhang L, Yang D, Zhao C, Zheng Y. Cold stress contributes to aberrant cytokinesis during male meiosis I in a wheat thermosensitive genic male sterile line. PLANT, CELL & ENVIRONMENT 2011; 34:389-405. [PMID: 21062315 DOI: 10.1111/j.1365-3040.2010.02250.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The male sterility of a wheat thermosensitive genic male sterile (TGMS) line is strictly controlled by temperature. When the TGMS line BS366 was exposed to 10 °C from the pollen mother cell stage to the meiosis stage, a few pollen grains were formed and devoid of starch. We report here a large-scale transcriptomic study using the Affymetrix wheat GeneChip to follow gene expression in BS366 line anthers in response to cold stress. Notably, many cytoskeletal signaling components were gradually induced in response to cold stress in BS366 line anthers. However, the cytoskeleton-associated genes that play key roles in the dynamic organization of the cytoskeleton were dramatically repressed. Histological studies revealed that the separation of dyads occurred abnormally during male meiosis I, indicating defective male meiotic cytokinesis. Fluorescence labelling and subcellular histological observations revealed that the phragmoplast was defectively formed and the cell plate was abnormally assembled during meiosis I under cold stress. Based on the transcriptomic analysis and observations of characterized histological changes, our results suggest that cold stress repressed transcription of cytoskeleton dynamic factors and subsequently caused the defective cytokinesis during meiosis I. The results may explain the male sterility caused by low temperature in wheat TGMS lines.
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Affiliation(s)
- Zonghui Tang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
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25
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Day B, Henty JL, Porter KJ, Staiger CJ. The pathogen-actin connection: a platform for defense signaling in plants. ANNUAL REVIEW OF PHYTOPATHOLOGY 2011; 49:483-506. [PMID: 21495845 DOI: 10.1146/annurev-phyto-072910-095426] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
The cytoskeleton, a dynamic network of cytoplasmic polymers, plays a central role in numerous fundamental processes, such as development, reproduction, and cellular responses to biotic and abiotic stimuli. As a platform for innate immune responses in mammalian cells, the actin cytoskeleton is a central component in the organization and activation of host defenses, including signaling and cellular repair. In plants, our understanding of the genetic and biochemical responses in both pathogen and host that are required for virulence and resistance has grown enormously. Additional advances in live-cell imaging of cytoskeletal dynamics have markedly altered our view of actin turnover in plants. In this review, we outline current knowledge of host resistance following pathogen perception, both in terms of the genetic interactions that mediate defense signaling, as well as the biochemical and cellular processes that are required for defense signaling.
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Affiliation(s)
- Brad Day
- Department of Plant Pathology, Michigan State University, East Lansing, Michigan 48824-1311, USA.
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Blanchoin L, Boujemaa-Paterski R, Henty JL, Khurana P, Staiger CJ. Actin dynamics in plant cells: a team effort from multiple proteins orchestrates this very fast-paced game. CURRENT OPINION IN PLANT BIOLOGY 2010; 13:714-23. [PMID: 20970372 DOI: 10.1016/j.pbi.2010.09.013] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 08/27/2010] [Accepted: 09/23/2010] [Indexed: 05/21/2023]
Abstract
Gazing at a giant redwood tree in the Pacific Northwest, that has grown to enormous heights over centuries, does little to convince one that plants are built for speed and versatility. Even at the cellular level, a system of polymers-the cell skeleton or cytoskeleton-integrates signals and generates subcellular structures spanning scales of a few nanometers to hundreds of micrometers that coordinate cell growth. The term cytoskeleton itself connotes a stable structure. Clearly, this is not the case. Recent studies using advanced imaging modalities reveal the plant actin cytoskeleton to be a highly dynamic, ever changing assemblage of polymers. These insights along with growing evidence about the biochemical/biophysical properties of plant cytoskeletal polymers, especially those obtained by single filament imaging and reconstituted systems of purified proteins analyzed by total internal reflection fluorescence microscopy, allow the generation of a unique model for the dynamic turnover of actin filaments, termed stochastic dynamics. Here, we review several significant advances and highlight opportunities that will position plants at the vanguard of research on actin organization and turnover. A challenge for the future will be to apply the power of reverse-genetics in several model organisms to test the molecular details of this new model.
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Affiliation(s)
- Laurent Blanchoin
- Institut de Recherches en Technologies et Sciences pour le Vivant - iRTSV, Laboratoire de Phyiologie Cellulaire et Végétale, Commissariat à l'Energie Atomique /Centre National de la Recherche Scientifique/Institut National de la Recherche Agronomique/Université Joseph Fourier, CEA Grenoble, F38054, Grenoble, France.
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Papuga J, Hoffmann C, Dieterle M, Moes D, Moreau F, Tholl S, Steinmetz A, Thomas C. Arabidopsis LIM proteins: a family of actin bundlers with distinct expression patterns and modes of regulation. THE PLANT CELL 2010; 22:3034-52. [PMID: 20817848 PMCID: PMC2965535 DOI: 10.1105/tpc.110.075960] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Revised: 07/04/2010] [Accepted: 08/19/2010] [Indexed: 05/18/2023]
Abstract
Recently, a number of two LIM-domain containing proteins (LIMs) have been reported to trigger the formation of actin bundles, a major higher-order cytoskeletal assembly. Here, we analyzed the six Arabidopsis thaliana LIM proteins. Promoter-β-glucuronidase reporter studies revealed that WLIM1, WLIM2a, and WLIM2b are widely expressed, whereas PLIM2a, PLIM2b, and PLIM2c are predominantly expressed in pollen. LIM-green fluorescent protein (GFP) fusions all decorated the actin cytoskeleton and increased actin bundle thickness in transgenic plants and in vitro, although with different affinities and efficiencies. Remarkably, the activities of WLIMs were calcium and pH independent, whereas those of PLIMs were inhibited by high pH and, in the case of PLIM2c, by high [Ca(2+)]. Domain analysis showed that the C-terminal domain is key for the responsiveness of PLIM2c to pH and calcium. Regulation of LIM by pH was further analyzed in vivo by tracking GFP-WLIM1 and GFP-PLIM2c during intracellular pH modifications. Cytoplasmic alkalinization specifically promoted release of GFP-PLIM2c but not GFP-WLIM1, from filamentous actin. Consistent with these data, GFP-PLIM2c decorated long actin bundles in the pollen tube shank, a region of relatively low pH. Together, our data support a prominent role of Arabidopsis LIM proteins in the regulation of actin cytoskeleton organization and dynamics in sporophytic tissues and pollen.
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Affiliation(s)
| | | | | | | | | | | | | | - Clément Thomas
- Centre de Recherche Public-Santé, L-1526 Luxembourg, Luxembourg
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Zhang H, Qu X, Bao C, Khurana P, Wang Q, Xie Y, Zheng Y, Chen N, Blanchoin L, Staiger CJ, Huang S. Arabidopsis VILLIN5, an actin filament bundling and severing protein, is necessary for normal pollen tube growth. THE PLANT CELL 2010; 22:2749-67. [PMID: 20807879 PMCID: PMC2947167 DOI: 10.1105/tpc.110.076257] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
A dynamic actin cytoskeleton is essential for pollen germination and tube growth. However, the molecular mechanisms underlying the organization and turnover of the actin cytoskeleton in pollen remain poorly understood. Villin plays a key role in the formation of higher-order structures from actin filaments and in the regulation of actin dynamics in eukaryotic cells. It belongs to the villin/gelsolin/fragmin superfamily of actin binding proteins and is composed of six gelsolin-homology domains at its core and a villin headpiece domain at its C terminus. Recently, several villin family members from plants have been shown to sever, cap, and bundle actin filaments in vitro. Here, we characterized a villin isovariant, Arabidopsis thaliana VILLIN5 (VLN5), that is highly and preferentially expressed in pollen. VLN5 loss-of-function retarded pollen tube growth and sensitized actin filaments in pollen grains and tubes to latrunculin B. In vitro biochemical analyses revealed that VLN5 is a typical member of the villin family and retains a full suite of activities, including barbed-end capping, filament bundling, and calcium-dependent severing. The severing activity was confirmed with time-lapse evanescent wave microscopy of individual actin filaments in vitro. We propose that VLN5 is a major regulator of actin filament stability and turnover that functions in concert with oscillatory calcium gradients in pollen and therefore plays an integral role in pollen germination and tube growth.
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Affiliation(s)
- Hua Zhang
- Center for Signal Transduction and Metabolomics, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaolu Qu
- Center for Signal Transduction and Metabolomics, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chanchan Bao
- Center for Signal Transduction and Metabolomics, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Parul Khurana
- Department of Biological Sciences and Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907-2064
| | - Qiannan Wang
- Center for Signal Transduction and Metabolomics, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yurong Xie
- Center for Signal Transduction and Metabolomics, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Yiyan Zheng
- Center for Signal Transduction and Metabolomics, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Graduate School of Chinese Academy of Sciences, Beijing, 100049, China
| | - Naizhi Chen
- Center for Signal Transduction and Metabolomics, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
| | - Laurent Blanchoin
- Institut de Recherches en Technologie et Sciences pour le Vivant, Laboratoire de Physiologie Cellulaire Végétale, Commissariat à l’Energie Atomique/Centre National de la Recherche Scientifique/Université Joseph Fourier, F38054 Grenoble, France
| | - Christopher J. Staiger
- Department of Biological Sciences and Bindley Bioscience Center, Purdue University, West Lafayette, Indiana 47907-2064
| | - Shanjin Huang
- Center for Signal Transduction and Metabolomics, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
- Address correspondence to
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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: 121] [Impact Index Per Article: 8.6] [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.
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Affiliation(s)
- Christopher J Staiger
- Department of Biological Sciences and Bindley Bioscience Center, Purdue University, West Lafayette, IN 47907-2064, USA.
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Thomas C, Tholl S, Moes D, Dieterle M, Papuga J, Moreau F, Steinmetz A. Actin bundling in plants. ACTA ACUST UNITED AC 2009; 66:940-57. [DOI: 10.1002/cm.20389] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Glycine-rich region regulates cysteine-rich protein 1 binding to actin cytoskeleton. Biochem Biophys Res Commun 2009; 380:484-8. [PMID: 19284992 DOI: 10.1016/j.bbrc.2009.01.125] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Accepted: 01/16/2009] [Indexed: 11/22/2022]
Abstract
Cysteine-rich protein 1 (CRP1) has a unique structure with two well separated LIM domains, each followed by a glycine-rich region. Although CRP1 has been shown to interact with actin-binding proteins and actin filaments, the mechanism regulating localization to the actin cytoskeleton in cells is not clear. Experiments using truncated forms showed that the first LIM domain and glycine-rich region are necessary for CRP1 bundling of actin filaments and localization to the actin cytoskeleton. Furthermore, domain swapping experiments replacing the first glycine-rich region with the second resulted in the loss of CRP1 bundling activity and localization to the actin cytoskeleton, identifying seven critical amino acid residues. These results highlight the importance of the first glycine-rich region for CRP1 bundling activity and localization to the actin cytoskeleton. In addition, this work identifies the first LIM domain and glycine-rich region as a distinct actin filament bundling module.
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Wang HJ, Wan AR, Jauh GY. An actin-binding protein, LlLIM1, mediates calcium and hydrogen regulation of actin dynamics in pollen tubes. PLANT PHYSIOLOGY 2008; 147:1619-36. [PMID: 18480376 PMCID: PMC2492651 DOI: 10.1104/pp.108.118604] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Actin microfilaments are crucial for polar cell tip growth, and their configurations and dynamics are regulated by the actions of various actin-binding proteins (ABPs). We explored the function of a lily (Lilium longiflorum) pollen-enriched LIM domain-containing protein, LlLIM1, in regulating the actin dynamics in elongating pollen tube. Cytological and biochemical assays verified LlLIM1 functioning as an ABP, promoting filamentous actin (F-actin) bundle assembly and protecting F-actin against latrunculin B-mediated depolymerization. Overexpressed LlLIM1 significantly disturbed pollen tube growth and morphology, with multiple tubes protruding from one pollen grain and coaggregation of FM4-64-labeled vesicles and Golgi apparatuses at the subapex of the tube tip. Moderate expression of LlLIM1 induced an oscillatory formation of asterisk-shaped F-actin aggregates that oscillated with growth period but in different phases at the subapical region. These results suggest that the formation of LlLIM1-mediated overstabilized F-actin bundles interfered with endomembrane trafficking to result in growth retardation. Cosedimentation assays revealed that the binding affinity of LlLIM1 to F-actin was simultaneously regulated by both pH and Ca(2+): LlLIM1 showed a preference for F-actin binding under low pH and low Ca(2+) concentration. The potential functions of LlLIM1 as an ABP sensitive to pH and calcium in integrating endomembrane trafficking, oscillatory pH, and calcium circumstances to regulate tip-focused pollen tube growth are discussed.
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Affiliation(s)
- Huei-Jing Wang
- Institute of Plant and Microbial Biology, Academia Sinica, Nankang, Taipei 115, Taiwan, Republic of China
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Thomas C, Dieterle M, Gatti S, Hoffmann C, Moreau F, Papuga J, Steinmetz A. Actin bundling via LIM domains. PLANT SIGNALING & BEHAVIOR 2008; 3:320-1. [PMID: 19841658 PMCID: PMC2634270 DOI: 10.4161/psb.3.5.5310] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2007] [Accepted: 11/19/2007] [Indexed: 05/21/2023]
Abstract
The LIM domain is defined as a protein-protein interaction module involved in the regulation of diverse cellular processes including gene expression and cytoskeleton organization. We have recently shown that the tobacco WLIM1, a two LIM domain-containing protein, is able to bind to, stabilize and bundle actin filaments, suggesting that it participates to the regulation of actin cytoskeleton structure and dynamics. In the December issue of the Journal of Biological Chemistry we report a domain analysis that specifically ascribes the actin-related activities of WLIM1 to its two LIM domains. Results suggest that LIM domains function synergistically in the full-length protein to achieve optimal activities. Here we briefly summarize relevant data regarding the actin-related properties/functions of two LIM domain-containing proteins in plants and animals. In addition, we provide further evidence of cooperative effects between LIM domains by transiently expressing a chimeric multicopy WLIM1 protein in BY2 cells.
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Affiliation(s)
- Clément Thomas
- Centre de Recherche Public-Santé; Val Fleuri 84; L-1526; Luxembourg
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Zheng B, Wen JK, Han M. hhLIM is a novel F-actin binding protein involved in actin cytoskeleton remodeling. FEBS J 2008; 275:1568-1578. [PMID: 18331358 DOI: 10.1111/j.1742-4658.2008.06315.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Human heart LIM protein (hhLIM) is a newly cloned protein. In vitro analyses showed that green fluorescent protein (GFP)-tagged hhLIM protein accumulated in the cytoplasm of C2C12 cells and colocalized with F-actin, indicating that hhLIM is an actin-binding protein in C2C12 cells. Overexpression of hhLIM-GFP in C2C12 cells significantly stabilized actin filaments and delayed depolymerization of the actin cytoskeleton induced by cytochalasin B treatment. Expression of hhLIM-GFP in C2C12 cells also induced significant changes in the organization of the actin cytoskeleton, specifically, fewer and thicker actin bundles than in control cells, suggesting that hhLIM functions as an actin-bundling protein. This hypothesis was confirmed using low-speed co-sedimentation assays and direct observation of F-actin bundles that formed in vitro in the presence of hhLIM. hhLIM has two LIM domains. To identify the essential regions and sites for association, a series of truncated mutants was constructed which showed that LIM domain 2 has the same activity as full-length hhLIM. To further characterize the binding sites, the LIM domain was functionally destructed by replacing cysteine with serine in domain 2, and results showed that the second LIM domain plays a central role in bundling of F-actin. Taken together, these data identify hhLIM as an actin-binding protein that increases actin cytoskeleton stability by promoting bundling of actin filaments.
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Affiliation(s)
- Bin Zheng
- Department of Biochemistry and Molecular Biology, Hebei Medical University, Shijiazhuang, China
| | - Jin-Kun Wen
- Department of Biochemistry and Molecular Biology, Hebei Medical University, Shijiazhuang, China
| | - Mei Han
- Department of Biochemistry and Molecular Biology, Hebei Medical University, Shijiazhuang, China
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