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Deng X, Peng FL, Tang X, Lee YRJ, Lin HH, Liu B. The Arabidopsis BUB1/MAD3 family protein BMF3 requires BUB3.3 to recruit CDC20 to kinetochores in spindle assembly checkpoint signaling. Proc Natl Acad Sci U S A 2024; 121:e2322677121. [PMID: 38466841 PMCID: PMC10963012 DOI: 10.1073/pnas.2322677121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 02/13/2024] [Indexed: 03/13/2024] Open
Abstract
The spindle assembly checkpoint (SAC) ensures faithful chromosome segregation during cell division by monitoring kinetochore-microtubule attachment. Plants produce both sequence-conserved and diverged SAC components, and it has been largely unknown how SAC activation leads to the assembly of these proteins at unattached kinetochores to prevent cells from entering anaphase. In Arabidopsis thaliana, the noncanonical BUB3.3 protein was detected at kinetochores throughout mitosis, unlike MAD1 and the plant-specific BUB1/MAD3 family protein BMF3 that associated with unattached chromosomes only. When BUB3.3 was lost by a genetic mutation, mitotic cells often entered anaphase with misaligned chromosomes and presented lagging chromosomes after they were challenged by low doses of the microtubule depolymerizing agent oryzalin, resulting in the formation of micronuclei. Surprisingly, BUB3.3 was not required for the kinetochore localization of other SAC proteins or vice versa. Instead, BUB3.3 specifically bound to BMF3 through two internal repeat motifs that were not required for BMF3 kinetochore localization. This interaction enabled BMF3 to recruit CDC20, a downstream SAC target, to unattached kinetochores. Taken together, our findings demonstrate that plant SAC utilizes unconventional protein interactions for arresting mitosis, with BUB3.3 directing BMF3's role in CDC20 recruitment, rather than the recruitment of BUB1/MAD3 proteins observed in fungi and animals. This distinct mechanism highlights how plants adapted divergent versions of conserved cell cycle machinery to achieve specialized SAC control.
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Affiliation(s)
- Xingguang Deng
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu610064, China
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA95616
| | - Felicia Lei Peng
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA95616
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA19104
| | - Xiaoya Tang
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu610064, China
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA95616
| | - Hong-Hui Lin
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu610064, China
| | - Bo Liu
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA95616
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2
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Deng X, He Y, Tang X, Liu X, Lee YRJ, Liu B, Lin H. A coadapted KNL1 and spindle assembly checkpoint axis orchestrates precise mitosis in Arabidopsis. Proc Natl Acad Sci U S A 2024; 121:e2316583121. [PMID: 38170753 PMCID: PMC10786300 DOI: 10.1073/pnas.2316583121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Accepted: 11/30/2023] [Indexed: 01/05/2024] Open
Abstract
The kinetochore scaffold 1 (KNL1) protein recruits spindle assembly checkpoint (SAC) proteins to ensure accurate chromosome segregation during mitosis. Despite such a conserved function among eukaryotic organisms, its molecular architectures have rapidly evolved so that the functional mode of plant KNL1 is largely unknown. To understand how SAC signaling is regulated at kinetochores, we characterized the function of the KNL1 gene in Arabidopsis thaliana. The KNL1 protein was detected at kinetochores throughout the mitotic cell cycle, and null knl1 mutants were viable and fertile but exhibited severe vegetative and reproductive defects. The mutant cells showed serious impairments of chromosome congression and segregation, that resulted in the formation of micronuclei. In the absence of KNL1, core SAC proteins were no longer detected at the kinetochores, and the SAC was not activated by unattached or misaligned chromosomes. Arabidopsis KNL1 interacted with SAC essential proteins BUB3.3 and BMF3 through specific regions that were not found in known KNL1 proteins of other species, and recruited them independently to kinetochores. Furthermore, we demonstrated that upon ectopic expression, the KNL1 homolog from the dicot tomato was able to functionally substitute KNL1 in A. thaliana, while others from the monocot rice or moss associated with kinetochores but were not functional, as reflected by sequence variations of the kinetochore proteins in different plant lineages. Our results brought insights into understanding the rapid evolution and lineage-specific connection between KNL1 and the SAC signaling molecules.
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Affiliation(s)
- Xingguang Deng
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu610064, China
| | - Ying He
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu610064, China
| | - Xiaoya Tang
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu610064, China
| | - Xianghong Liu
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu610064, China
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA95616
| | - Bo Liu
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA95616
| | - Honghui Lin
- Ministry of Education Key Laboratory for Bio-Resource and Eco-Environment, College of Life Sciences, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu610064, China
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Chiu CL, Hong SY, Tan Y, Lee YRJ, Shih YP, Tepper CG, Lo SH. C-terminal tensin-like ( CTEN) knockin alleviates cystic kidney defects in Tensin-1 knockout mice. Genes Dis 2023; 10:643-646. [PMID: 37396551 PMCID: PMC10308109 DOI: 10.1016/j.gendis.2022.05.035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 04/08/2022] [Accepted: 05/30/2022] [Indexed: 11/26/2022] Open
Affiliation(s)
- Chun-Lung Chiu
- Department of Biochemistry and Molecular Medicine, University of California-Davis, Sacramento, CA 95817, USA
| | - Shiao-Ya Hong
- Department of Biochemistry and Molecular Medicine, University of California-Davis, Sacramento, CA 95817, USA
| | - Ying Tan
- Department of Biochemistry and Molecular Medicine, University of California-Davis, Sacramento, CA 95817, USA
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, University of California-Davis, Davis, CA 95616, USA
| | - Yi-Ping Shih
- Department of Biochemistry and Molecular Medicine, University of California-Davis, Sacramento, CA 95817, USA
| | - Clifford G. Tepper
- Department of Biochemistry and Molecular Medicine, University of California-Davis, Sacramento, CA 95817, USA
| | - Su Hao Lo
- Department of Plant Biology, University of California-Davis, Davis, CA 95616, USA
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Lee YRJ, Yamada S, Lo SH. Phase transition of tensin-1 during the focal adhesion disassembly and cell division. Proc Natl Acad Sci U S A 2023; 120:e2303037120. [PMID: 37011205 PMCID: PMC10104483 DOI: 10.1073/pnas.2303037120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Accepted: 03/09/2023] [Indexed: 04/05/2023] Open
Abstract
Biomolecular condensates are nonmembranous structures that are mainly formed through liquid-liquid phase separation. Tensins are focal adhesion (FA) proteins linking the actin cytoskeleton to integrin receptors. Here, we report that GFP-tagged tensin-1 (TNS1) proteins phase-separate to form biomolecular condensates in cells. Live-cell imaging showed that new TNS1 condensates are budding from the disassembling ends of FAs, and the presence of these condensates is cell cycle dependent. TNS1 condensates dissolve immediately prior to mitosis and rapidly reappear while postmitotic daughter cells establish new FAs. TNS1 condensates contain selected FA proteins and signaling molecules such as pT308Akt but not pS473Akt, suggesting previously unknown roles of TNS1 condensates in disassembling FAs, as the storage of core FA components and the signaling intermediates.
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Affiliation(s)
- Yuh-Ru Julie Lee
- Department of Plant Biology, University of California, Davis, CA95616
| | - Soichiro Yamada
- Department of Biomedical Engineering, University of California, Davis, CA95616
| | - Su Hao Lo
- Department of Biochemistry and Molecular Medicine, University of California, Davis, CA95817
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Lee YRJ, Huang CH, Liu B. Confocal Microscopic Assays of Mitotically Active Proteins in an Agrobacterial Infiltration-Based, Cell Division-Enabled Leaf System of Tobacco (Nicotiana benthamiana). Methods Mol Biol 2023; 2604:103-111. [PMID: 36773228 DOI: 10.1007/978-1-0716-2867-6_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
Abstract
The production of tissues and organs in plants is brought about by mitotic cell divisions, starting from the zygote. Successful mitosis and cytokinesis harness the functional input of proteins that are expressed in cell cycle-dependent manners to regulate cytoskeletal reorganization and intracellular motility. Fluorescence microscopic assays of mitotically active proteins have been dependent on time-consuming transformation experiments in a host plant or cultured cells. To facilitate the detection and observation of cell cycle-dependent localization and dynamics of plant proteins, we demonstrate, in this chapter, a transiently induced cell division system in Nicotiana benthamiana, named the cell division-enabled leaf system (CDELS). Plasmid constructs which express the D-type cyclin along with a fluorescent fusion protein(s) of interest are delivered to the leaves of N. benthamiana by agrobacterial infiltration. Ectopic expression of cyclin D induces leaf epidermal cells to re-enter mitosis and subsequently cytokinesis, allowing the dynamic localization of fluorescent fusion protein(s) to be observed throughout the course of mitotic cell division using live-cell fluorescence microscopy. This effective approach not only allows one to detect mitotic activities of novel proteins but also record their dynamics and relationship with others during mitosis and cytokinesis in a greatly shortened period of time.
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Affiliation(s)
- Yuh-Ru Julie Lee
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA
| | - Calvin H Huang
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA
| | - Bo Liu
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA.
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Hotta T, Lee YRJ, Higaki T, Hashimoto T, Liu B. Two Kinesin-14A Motors Oligomerize to Drive Poleward Microtubule Convergence for Acentrosomal Spindle Morphogenesis in Arabidopsis thaliana. Front Cell Dev Biol 2022; 10:949345. [PMID: 35982853 PMCID: PMC9380777 DOI: 10.3389/fcell.2022.949345] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 06/16/2022] [Indexed: 11/13/2022] Open
Abstract
Plant cells form acentrosomal spindles with microtubules (MTs) converged toward two structurally undefined poles by employing MT minus end-directed Kinesin-14 motors. To date, it is unclear whether the convergent bipolar MT array assumes unified poles in plant spindles, and if so, how such a goal is achieved. Among six classes of Kinesin-14 motors in Arabidopsis thaliana, the Kinesin-14A motors ATK1 (KatA) and ATK5 share the essential function in spindle morphogenesis. To understand how the two functionally redundant Kinesin-14A motors contributed to the spindle assembly, we had ATK1-GFP and ATK5-GFP fusion proteins expressed in their corresponding null mutants and found that they were functionally comparable to their native forms. Although ATK1 was a nuclear protein and ATK5 cytoplasmic prior to nuclear envelop breakdown, at later mitotic stages, the two motors shared similar localization patterns of uniform association with both spindle and phragmoplast MTs. We found that ATK1 and ATK5 were rapidly concentrated toward unified polar foci when cells were under hyperosmotic conditions. Concomitantly, spindle poles became perfectly focused as if there were centrosome-like MT-organizing centers where ATK1 and ATK5 were highly enriched and at which kinetochore fibers pointed. The separation of ATK1/ATK5-highlighted MTs from those of kinetochore fibers suggested that the motors translocated interpolar MTs. Our protein purification and live-cell imaging results showed that ATK1 and ATK5 are associated with each other in vivo. The stress-induced spindle pole convergence was also accompanied by poleward accumulation of the MT nucleator γ-tubulin. These results led to the conclusion that the two Kinesin-14A motors formed oligomeric motor complexes that drove MT translocation toward the spindle pole to establish acentrosomal spindles with convergent poles.
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Affiliation(s)
- Takashi Hotta
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, Davis, CA, United States
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, United States
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Japan
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, Davis, CA, United States
| | - Takumi Higaki
- Faculty of Advanced Science and Technology, Kumamoto University, Kumamoto, Japan
- International Research Organization for Advanced Science and Technology, Kumamoto University, Kumamoto, Japan
| | - Takashi Hashimoto
- Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Japan
| | - Bo Liu
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, Davis, CA, United States
- *Correspondence: Bo Liu,
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Abstract
In contrast to well-studied fungal and animal cells, plant cells assemble bipolar spindles that exhibit a great deal of plasticity in the absence of structurally defined microtubule-organizing centers like the centrosome. While plants employ some evolutionarily conserved proteins to regulate spindle morphogenesis and remodeling, many essential spindle assembly factors found in vertebrates are either missing or not required for producing the plant bipolar microtubule array. Plants also produce proteins distantly related to their fungal and animal counterparts to regulate critical events such as the spindle assembly checkpoint. Plant spindle assembly initiates with microtubule nucleation on the nuclear envelope followed by bipolarization into the prophase spindle. After nuclear envelope breakdown, kinetochore fibers are assembled and unified into the spindle apparatus with convergent poles. Of note, compared to fungal and animal systems, relatively little is known about how plant cells remodel the spindle microtubule array during anaphase. Uncovering mitotic functions of novel proteins for spindle assembly in plants will illuminate both common and divergent mechanisms employed by different eukaryotic organisms to segregate genetic materials.
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Affiliation(s)
- Bo Liu
- Department of Plant Biology, University of California, Davis, California, USA; ,
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, University of California, Davis, California, USA; ,
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8
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Xu J, Lee YRJ, Liu B. Establishment of a mitotic model system by transient expression of the D-type cyclin in differentiated leaf cells of tobacco (Nicotiana benthamiana). New Phytol 2020; 226:1213-1220. [PMID: 31679162 DOI: 10.1111/nph.16309] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 10/28/2019] [Indexed: 05/12/2023]
Abstract
Investigations of plant cell division would greatly benefit from a fast, inducible system. Therefore, we aimed to establish a mitotic model by transiently expressing D-type cyclins in tobacco leaf cells. Two different D-type cyclins, CYCD3;1 and CYCD4;2 from Arabidopsis thaliana, were expressed by agrobacterial infiltration in the cells of expanded leaves in tobacco (Nicotiana benthamiana). Leaf pavement cells were examined after cyclin expression while target and reference (histone or tubulin) proteins were marked by fluorescent protein-tagging. Ectopic expression of the D-type cyclin induced pavement cells to re-enter cell division by establishing mitotic microtubule arrays. The induced leaf cells expressed M phase-specific genes of Arabidopsis encoding the mitotic kinase AtAurora 1, the microtubule-associated proteins AtEDE1 and AtMAP65-4, and the vesicle fusion protein AtKNOLLE by recognizing their genomic elements. Their distinct localizations at spindle poles (AtAurora1), spindle microtubules (AtEDE1), phragmoplast microtubules (AtMAP65-4) and the cell plate (AtKNOLLE) were indistinguishable from those in their native Arabidopsis cells. The dividing cells also revealed two rice (Oryza sativa) microtubule-associated proteins in the phragmoplast and uncovered a novel spindle-associated microtubule motor protein. Hence, this cell division-enabled leaf system predicts hypothesized cell cycle-dependent functions of heterologous genes by reporting the dynamics of encoded proteins.
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Affiliation(s)
- Jie Xu
- Key Laboratory of Crop Physiology, Ecology, and Genetic Breeding of the Ministry of Education, Jiangxi Agricultural University, Nanchang, Jiangxi, 330045, China
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, 95616, USA
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, 95616, USA
| | - Bo Liu
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, 95616, USA
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Wu ZY, Chiu CL, Lo E, Lee YRJ, Yamada S, Lo SH. Hyperactivity of Mek in TNS1 knockouts leads to potential treatments for cystic kidney diseases. Cell Death Dis 2019; 10:871. [PMID: 31740667 PMCID: PMC6861224 DOI: 10.1038/s41419-019-2119-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 09/28/2019] [Accepted: 11/05/2019] [Indexed: 12/29/2022]
Abstract
Cystic kidney disease is the progressive development of multiple fluid-filled cysts that may severely compromise kidney functions and lead to renal failure. TNS1 (tensin-1) knockout mice develop cystic kidneys and die from renal failure. Here, we have established TNS1-knockout MDCK cells and applied 3D culture system to investigate the mechanism leading to cyst formation. Unlike wild-type MDCK cells, which form cysts with a single lumen, TNS1-knockout cysts contain multiple lumens and upregulated Mek/Erk activities. The multiple lumen phenotype and Mek/Erk hyperactivities are rescued by re-expression of wild-type TNS1 but not the TNS1 mutant lacking a fragment essential for its cell–cell junction localization. Furthermore, Mek inhibitor treatments restore the multiple lumens back to single lumen cysts. Mek/Erk hyperactivities are also detected in TNS1-knockout mouse kidneys. Treatment with the Mek inhibitor trametinib significantly reduces the levels of interstitial infiltrates, fibrosis and dilated tubules in TNS1-knockout kidneys. These studies establish a critical role of subcellular localization of TNS1 in suppressing Mek/Erk signaling and maintaining lumenogenesis, and provide potential therapeutic strategies by targeting the Mek/Erk pathway for cystic kidney diseases.
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Affiliation(s)
- Zong-Ye Wu
- Department of Biochemistry and Molecular Medicine, University of California-Davis, Sacramento, CA, 95817, USA
| | - Chun-Lung Chiu
- Department of Biochemistry and Molecular Medicine, University of California-Davis, Sacramento, CA, 95817, USA
| | - Ethan Lo
- Department of Biochemistry and Molecular Medicine, University of California-Davis, Sacramento, CA, 95817, USA
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, University of California-Davis, Davis, CA, 95616, USA
| | - Soichiro Yamada
- Department of Biomedical Engineering, University of California-Davis, Davis, CA, 95616, USA
| | - Su Hao Lo
- Department of Biochemistry and Molecular Medicine, University of California-Davis, Sacramento, CA, 95817, USA.
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Lee YRJ, Liu B. Microtubule nucleation for the assembly of acentrosomal microtubule arrays in plant cells. New Phytol 2019; 222:1705-1718. [PMID: 30681146 DOI: 10.1111/nph.15705] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 01/07/2019] [Indexed: 05/15/2023]
Abstract
Contents Summary I. Introduction II. MT arrays in plant cells III. γ-Tubulin and MT nucleation IV. MT nucleation sites or flexible MTOCs in plant cells V. MT-dependent MT nucleation VI. Generating new MTs for spindle assembly VII. Generation of MTs for phragmoplast expansion during cytokinesis VIII. MT generation for the cortical MT array IX. MT nucleation: looking forward Acknowledgements References SUMMARY: Cytoskeletal microtubules (MTs) have a multitude of functions including intracellular distribution of molecules and organelles, cell morphogenesis, as well as segregation of the genetic material and separation of the cytoplasm during cell division among eukaryotic organisms. In response to internal and external cues, eukaryotic cells remodel their MT network in a regulated manner in order to assemble physiologically important arrays for cell growth, cell proliferation, or for cells to cope with biotic or abiotic stresses. Nucleation of new MTs is a critical step for MT remodeling. Although many key factors contributing to MT nucleation and organization are well conserved in different kingdoms, the centrosome, representing the most prominent microtubule organizing centers (MTOCs), disappeared during plant evolution as angiosperms lack the structure. Instead, flexible MTOCs may emerge on the plasma membrane, the nuclear envelope, and even organelles depending on types of cells and organisms and/or physiological conditions. MT-dependent MT nucleation is particularly noticeable in plant cells because it accounts for the primary source of MT generation for assembling spindle, phragmoplast, and cortical arrays when the γ-tubulin ring complex is anchored and activated by the augmin complex. It is intriguing what proteins are associated with plant-specific MTOCs and how plant cells activate or inactivate MT nucleation activities in spatiotemporally regulated manners.
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Affiliation(s)
- Yuh-Ru Julie Lee
- Department of Plant Biology, University of California, Davis, CA, 95616, USA
| | - Bo Liu
- Department of Plant Biology, University of California, Davis, CA, 95616, USA
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Zhang H, Deng X, Sun B, Van SL, Kang Z, Lin H, Lee YRJ, Liu B. Publisher Correction: Role of the BUB3 protein in phragmoplast microtubule reorganization during cytokinesis. Nat Plants 2018; 4:731. [PMID: 30087424 DOI: 10.1038/s41477-018-0215-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In the version of this Article originally published, the affiliation for author Yuh-Ru Julie Lee was incorrect; the correct affiliation is '2Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA'. This has now been amended in all versions of the Article.
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Affiliation(s)
- Hongchang Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA
| | - Xingguang Deng
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA
- College of Life Sciences, Sichuan University, Chengdu, Sichuan, China
| | - Baojuan Sun
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA
- Vegetable Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China
| | - Sonny Lee Van
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Honghui Lin
- College of Life Sciences, Sichuan University, Chengdu, Sichuan, China
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA
| | - Bo Liu
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA.
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Zhang H, Deng X, Sun B, Lee Van S, Kang Z, Lin H, Lee YRJ, Liu B. Role of the BUB3 protein in phragmoplast microtubule reorganization during cytokinesis. Nat Plants 2018; 4:485-494. [PMID: 29967519 DOI: 10.1038/s41477-018-0192-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Accepted: 06/04/2018] [Indexed: 05/15/2023]
Abstract
The evolutionarily conserved WD40 protein budding uninhibited by benzimidazole 3 (BUB3) is known for its function in spindle assembly checkpoint control. In the model plant Arabidopsis thaliana, nearly identical BUB3;1 and BUB3;2 proteins decorated the phragmoplast midline through interaction with the microtubule-associated protein MAP65-3 during cytokinesis. BUB3;1 and BUB3;2 interacted with the carboxy-terminal segment of MAP65-3 (but not MAP65-1), which harbours its microtubule-binding domain for its post-mitotic localization. Reciprocally, BUB3;1 and BUB3;2 also regulated MAP65-3 localization in the phragmoplast by enhancing its microtubule association. In the bub3;1 bub3;2 double mutant, MAP65-3 localization was often dissipated away from the phragmoplast midline and abolished upon treatment of low doses of the cytokinesis inhibitory drug caffeine that were tolerated by the control plant. The phragmoplast microtubule array exhibited uncoordinated expansion pattern in the double mutant cells as the phragmoplast edge reached the parental plasma membrane at different times in different areas. Upon caffeine treatment, phragmoplast expansion was halted as if the microtubule array was frozen. As a result, cytokinesis was abolished due to failed cell plate assembly. Our findings have uncovered a novel function of the plant BUB3 in MAP65-3-dependent microtubule reorganization during cytokinesis.
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Affiliation(s)
- Hongchang Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, China
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA
| | - Xingguang Deng
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA
- College of Life Sciences, Sichuan University, Chengdu, Sichuan, China
| | - Baojuan Sun
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA
- Vegetable Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China
| | - Sonny Lee Van
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA
| | - Zhensheng Kang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, China
| | - Honghui Lin
- College of Life Sciences, Sichuan University, Chengdu, Sichuan, China
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA.
| | - Bo Liu
- Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA, USA.
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Lee YRJ, Hiwatashi Y, Hotta T, Xie T, Doonan JH, Liu B. The Mitotic Function of Augmin Is Dependent on Its Microtubule-Associated Protein Subunit EDE1 in Arabidopsis thaliana. Curr Biol 2017; 27:3891-3897.e4. [DOI: 10.1016/j.cub.2017.11.030] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Revised: 09/30/2017] [Accepted: 11/09/2017] [Indexed: 01/13/2023]
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Lv S, Miao H, Luo M, Li Y, Wang Q, Julie Lee YR, Liu B. CAPPI: A Cytoskeleton-Based Localization Assay Reports Protein-Protein Interaction in Living Cells by Fluorescence Microscopy. Mol Plant 2017; 10:1473-1476. [PMID: 28939449 DOI: 10.1016/j.molp.2017.09.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 09/01/2017] [Accepted: 09/10/2017] [Indexed: 06/07/2023]
Affiliation(s)
- Sulian Lv
- Department of Plant Biology, University of California, Davis, CA 95616, USA; Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Huiying Miao
- Department of Plant Biology, University of California, Davis, CA 95616, USA; Department of Horticulture, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Ming Luo
- Department of Plant Biology, University of California, Davis, CA 95616, USA; Biotechnology Research Center, Southwest University, Chongqing, 400716, China
| | - Yinxin Li
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, China
| | - Qiaomei Wang
- Department of Horticulture, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Bo Liu
- Department of Plant Biology, University of California, Davis, CA 95616, USA.
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15
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Lee YRJ, Qiu W, Liu B. Kinesin motors in plants: from subcellular dynamics to motility regulation. Curr Opin Plant Biol 2015; 28:120-126. [PMID: 26556761 DOI: 10.1016/j.pbi.2015.10.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 09/30/2015] [Accepted: 10/07/2015] [Indexed: 06/05/2023]
Abstract
Plants produce enormous forms of the microtubule (MT)-based motor kinesins that have been inspiring plant cell biologists to uncover their functions in relation to plant growth and development. Subcellular localization of kinesin proteins detected through live-cell imaging or immunofluorescence microscopy has provided great insights into the functions of these motors. Dozens of mitotic kinesins exhibit particularly splendid localization patterns from chromosomes and kinetochores to MT arrays like the preprophase band, spindle poles, the spindle midzone, phragmoplast distal ends, and the phragmoplast midzone. Different subcellular localizations indicate distinct functions of these motors that are yet to be characterized. The localization difference between plant kinesins and their animal counterparts implies mechanistic differences in mitosis and cytokinesis between the two kingdoms. When many forms of kinesins are present simultaneously, it becomes critical that their motility is differentially regulated with spatial and temporal precision. Insights into regulatory mechanisms of motors can often be brought about by in vitro single-molecule biophysical studies. Significant advances are expected in this area in the coming years owing to rapid technological advances that are being brought to various model plants.
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Affiliation(s)
- Yuh-Ru Julie Lee
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Weihong Qiu
- Departments of Physics and Biophysics & Biochemistry, Oregon State University, Covallis, OR 97331, USA
| | - Bo Liu
- Department of Plant Biology, University of California, Davis, CA 95616, USA.
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16
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Kong Z, Ioki M, Braybrook S, Li S, Ye ZH, Julie Lee YR, Hotta T, Chang A, Tian J, Wang G, Liu B. Kinesin-4 Functions in Vesicular Transport on Cortical Microtubules and Regulates Cell Wall Mechanics during Cell Elongation in Plants. Mol Plant 2015; 8:1011-23. [PMID: 25600279 DOI: 10.1016/j.molp.2015.01.004] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 01/02/2015] [Accepted: 01/07/2015] [Indexed: 05/20/2023]
Abstract
In plants, anisotropic cell expansion depends on cortical microtubules that serve as tracks along which macromolecules and vesicles are transported by the motor kinesins of unknown identities. We used cotton (Gossypium hirsutum) fibers that underwent robust elongation to discover kinesins that are involved in cell elongation and found Gh KINESIN-4A expressed abundantly. The motor was detected by immunofluorescence on vesicle-like structures that were associated with cortical microtubules. In Arabidopsis thaliana, the orthologous motor At KINESIN-4A/FRA1, previously implicated in cellulose deposition during secondary growth in fiber cells, was examined by live-cell imaging in cells expressing the fluorescently tagged functional protein. The motor decorated vesicle-like particles that exhibit a linear movement along cortical microtubules with an average velocity of 0.89 μm/min, which was significantly different from those linked to cellulose biosynthesis. We also discovered that At KINESIN-4A/FRA1 and the related At KINESIN-4C play redundant roles in cell wall mechanics, cell elongation, and the axial growth of various vegetative and reproductive organs, as the loss of At KINESIN-4C greatly enhanced the defects caused by a null mutation at the KINESIN-4A/FRA1 locus. The double mutant displayed a lack of cell wall softening at normal stages of rapid cell elongation. Furthermore, enhanced deposition of arabinose-containing carbohydrate was detected in the kinesin-4 mutants. Our findings established a connection between the Kinesin-4-based transport of cargoes containing non-cellulosic components along cortical microtubules and cell wall mechanics and cell elongation in flowering plants.
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Affiliation(s)
- Zhaosheng Kong
- Department of Plant Biology, University of California, Davis, CA 95616, USA; State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Motohide Ioki
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Siobhan Braybrook
- Sainsbury Laboratory Cambridge, University of Cambridge, Cambridge CB2 1LR, UK
| | - Shundai Li
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, State College, PA 16802, USA
| | - Zheng-Hua Ye
- Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Takashi Hotta
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Anny Chang
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Juan Tian
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Guangda Wang
- State Key Laboratory of Plant Genomics, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Bo Liu
- Department of Plant Biology, University of California, Davis, CA 95616, USA.
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17
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Lee YRJ, Liu B. The rise and fall of the phragmoplast microtubule array. Curr Opin Plant Biol 2013; 16:757-63. [PMID: 24172707 DOI: 10.1016/j.pbi.2013.10.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 10/15/2013] [Accepted: 10/16/2013] [Indexed: 05/21/2023]
Abstract
The cytokinetic apparatus, the phragmoplast, contains a bipolar microtubule (MT) framework that has the MT plus ends concentrated at or near the division site. This anti-parallel MT array provides tracks for the transport of Golgi-derived vesicles toward the plus ends so that materials enclosed are subsequently deposited at the division site. Here we will discuss a proposed model of the centrifugal expansion of the phragmoplast that takes place concomitantly with the assembly of the cell plate, the ultimate product of vesicle fusion. The expansion is a result of continuous MT assembly at the phragmoplast periphery while the MTs toward the center of the phragmoplast are disassembled. These events are the result of MT-dependent MT polymerization, bundling of anti-parallel MTs coming from opposite sides of the division plane that occurs selectively at the phragmoplast periphery, positioning of the plus ends of cross-linked MTs at or near the division site by establishing a minimal MT-overlapping zone, and debundling of anti-parallel MTs that is triggered by phosphorylation of MT-associated proteins. The debundled MTs are disassembled at last by factors including the MT severing enzyme katanin.
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Affiliation(s)
- Yuh-Ru Julie Lee
- Department of Plant Biology, University of California, Davis, CA 95616, USA
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18
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Ho CMK, Lee YRJ, Kiyama LD, Dinesh-Kumar SP, Liu B. Arabidopsis microtubule-associated protein MAP65-3 cross-links antiparallel microtubules toward their plus ends in the phragmoplast via its distinct C-terminal microtubule binding domain. Plant Cell 2012; 24:2071-85. [PMID: 22570443 PMCID: PMC3442588 DOI: 10.1105/tpc.111.092569] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 04/11/2012] [Accepted: 04/23/2012] [Indexed: 05/19/2023]
Abstract
Plant cytokinesis is brought about by the phragmoplast, which contains an antiparallel microtubule (MT) array. The MT-associated protein MAP65-3 acts as an MT-bundling factor that specifically cross-links antiparallel MTs near their plus ends. MAP65 family proteins contain an N-terminal dimerization domain and C-terminal MT interaction domain. Compared with other MAP65 isoforms, MAP65-3 contains an extended C terminus. A MT binding site was discovered in the region between amino acids 496 and 588 and found to be essential for the organization of phragmoplast MTs. The frequent cytokinetic failure caused by loss of MAP65-3 was not rescued by ectopic expression of MAP65-1 under the control of the MAP65-3 promoter, indicating nonoverlapping functions between the two isoforms. In the presence of MAP65-3, however, ectopic MAP65-1 appeared in the phragmoplast midline. We show that MAP65-1 could acquire the function of MAP65-3 when the C terminus of MAP65-3, which contains the MT binding site, was grafted to it. Our results also show that MAP65-1 and MAP65-3 may share redundant functions in MT stabilization. Such a stabilization effect was likely brought about by MT binding and bundling. We conclude that MAP65-3 contains a distinct C-terminal MT binding site with a specific role in cross-linking antiparallel MTs toward their plus ends in the phragmoplast.
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Affiliation(s)
| | | | | | | | - Bo Liu
- Address correspondence to
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19
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Hotta T, Kong Z, Ho CMK, Zeng CJT, Horio T, Fong S, Vuong T, Lee YRJ, Liu B. Characterization of the Arabidopsis augmin complex uncovers its critical function in the assembly of the acentrosomal spindle and phragmoplast microtubule arrays. Plant Cell 2012; 24:1494-509. [PMID: 22505726 PMCID: PMC3398559 DOI: 10.1105/tpc.112.096610] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 03/10/2012] [Accepted: 03/20/2012] [Indexed: 05/19/2023]
Abstract
Plant cells assemble the bipolar spindle and phragmoplast microtubule (MT) arrays in the absence of the centrosome structure. Our recent findings in Arabidopsis thaliana indicated that AUGMIN subunit3 (AUG3), a homolog of animal dim γ-tubulin 3, plays a critical role in γ-tubulin-dependent MT nucleation and amplification during mitosis. Here, we report the isolation of the entire plant augmin complex that contains eight subunits. Among them, AUG1 to AUG6 share low sequence similarity with their animal counterparts, but AUG7 and AUG8 share homology only with proteins of plant origin. Genetic analyses indicate that the AUG1, AUG2, AUG4, and AUG5 genes are essential, as stable mutations in these genes could only be transmitted to heterozygous plants. The sterile aug7-1 homozygous mutant in which AUG7 expression is significantly reduced exhibited pleiotropic phenotypes of seriously retarded vegetative and reproductive growth. The aug7-1 mutation caused delocalization of γ-tubulin in the mitotic spindle and phragmoplast. Consequently, spindles were abnormally elongated, and their poles failed to converge, as MTs were splayed to discrete positions rendering deformed arrays. In addition, the mutant phragmoplasts often had disorganized MT bundles with uneven edges. We conclude that assembly of MT arrays during plant mitosis depends on the augmin complex, which includes two plant-specific subunits.
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Affiliation(s)
- Takashi Hotta
- Department of Plant Biology, University of California, Davis, California 95616
| | - Zhaosheng Kong
- Department of Plant Biology, University of California, Davis, California 95616
| | - Chin-Min Kimmy Ho
- Department of Plant Biology, University of California, Davis, California 95616
| | - Cui Jing Tracy Zeng
- Department of Plant Biology, University of California, Davis, California 95616
| | - Tetsuya Horio
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045
| | - Sophia Fong
- Department of Plant Biology, University of California, Davis, California 95616
| | - Trang Vuong
- Department of Plant Biology, University of California, Davis, California 95616
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, University of California, Davis, California 95616
| | - Bo Liu
- Department of Plant Biology, University of California, Davis, California 95616
- Address correspondence to
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20
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Ho CMK, Hotta T, Guo F, Roberson RW, Lee YRJ, Liu B. Interaction of antiparallel microtubules in the phragmoplast is mediated by the microtubule-associated protein MAP65-3 in Arabidopsis. Plant Cell 2011; 23:2909-23. [PMID: 21873565 PMCID: PMC3180800 DOI: 10.1105/tpc.110.078204] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Revised: 06/28/2011] [Accepted: 08/04/2011] [Indexed: 05/18/2023]
Abstract
In plant cells, microtubules (MTs) in the cytokinetic apparatus phragmoplast exhibit an antiparallel array and transport Golgi-derived vesicles toward MT plus ends located at or near the division site. By transmission electron microscopy, we observed that certain antiparallel phragmoplast MTs overlapped and were bridged by electron-dense materials in Arabidopsis thaliana. Robust MT polymerization, reported by fluorescently tagged End Binding1c (EB1c), took place in the phragmoplast midline. The engagement of antiparallel MTs in the central spindle and phragmoplast was largely abolished in mutant cells lacking the MT-associated protein, MAP65-3. We found that endogenous MAP65-3 was selectively detected on the middle segments of the central spindle MTs at late anaphase. When MTs exhibited a bipolar appearance with their plus ends placed in the middle, MAP65-3 exclusively decorated the phragmoplast midline. A bacterially expressed MAP65-3 protein was able to establish the interdigitation of MTs in vitro. MAP65-3 interacted with antiparallel microtubules before motor Kinesin-12 did during the establishment of the phragmoplast MT array. Thus, MAP65-3 selectively cross-linked interdigitating MTs (IMTs) to allow antiparallel MTs to be closely engaged in the phragmoplast. Although the presence of IMTs was not essential for vesicle trafficking, they were required for the phragmoplast-specific motors Kinesin-12 and Phragmoplast-Associated Kinesin-Related Protein2 to interact with MT plus ends. In conclusion, we suggest that the phragmoplast contains IMTs and highly dynamic noninterdigitating MTs, which work in concert to bring about cytokinesis in plant cells.
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Affiliation(s)
- Chin-Min Kimmy Ho
- Department of Plant Biology, University of California, Davis, CA 95616
| | - Takashi Hotta
- Department of Plant Biology, University of California, Davis, CA 95616
| | - Fengli Guo
- Department of Plant Biology, University of California, Davis, CA 95616
| | | | - Yuh-Ru Julie Lee
- Department of Plant Biology, University of California, Davis, CA 95616
| | - Bo Liu
- Department of Plant Biology, University of California, Davis, CA 95616
- Address correspondence to
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21
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Kimmy Ho CM, Hotta T, Kong Z, Tracy Zeng CJ, Sun J, Julie Lee YR, Liu B. Augmin plays a critical role in organizing the spindle and phragmoplast microtubule arrays in Arabidopsis. Plant Cell 2011; 23:2606-18. [PMID: 21750235 PMCID: PMC3226208 DOI: 10.1105/tpc.111.086892] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2011] [Revised: 06/12/2011] [Accepted: 06/28/2011] [Indexed: 05/19/2023]
Abstract
In higher plant cells, microtubules (MTs) are nucleated and organized in a centrosome-independent manner. It is unclear whether augmin-dependent mechanisms underlie spindle MT organization in plant cells as they do in animal cells. When AUGMIN subunit3 (AUG3), which encodes a homolog of animal dim γ-tubulin 3/human augmin-like complex, subunit 3, was disrupted in Arabidopsis thaliana, gametogenesis frequently failed due to defects in cell division. Compared with the control microspores, which formed bipolar spindles at the cell periphery, the mutant cells often formed peripheral half spindles that only attached to condensed chromosomes or formed elongated spindles with unfocused interior poles. In addition, defective cells exhibited disorganized phragmoplast MT arrays, which caused aborted cytokinesis. The resulting pollen grains were either shrunken or contained two nuclei in an undivided cytoplasm. AUG3 was localized along MTs in the spindle and phragmoplast, and its signal was pronounced in anaphase spindle poles. An AUG3-green fluorescent protein fusion exhibited a dynamic distribution pattern, similar to that of the γ-tubulin complex protein2. When AUG3 was enriched from seedlings by affinity chromatography, AUG1 was detected by immunoblotting, suggesting an augmin-like complex was present in vivo. We conclude that augmin plays a critical role in MT organization during plant cell division.
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Affiliation(s)
- Chin-Min Kimmy Ho
- Department of Plant Biology, University of California, Davis, California 95616
| | - Takashi Hotta
- Department of Plant Biology, University of California, Davis, California 95616
| | - Zhaosheng Kong
- Department of Plant Biology, University of California, Davis, California 95616
| | - Cui Jing Tracy Zeng
- Department of Plant Biology, University of California, Davis, California 95616
| | - Jie Sun
- Department of Plant Biology, University of California, Davis, California 95616
- College of Agriculture, Shihezi University, Shihezi, Xinjiang 832003, China
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, University of California, Davis, California 95616
| | - Bo Liu
- Department of Plant Biology, University of California, Davis, California 95616
- Address correspondence to
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22
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Liu B, Ho CMK, Lee YRJ. Microtubule Reorganization during Mitosis and Cytokinesis: Lessons Learned from Developing Microgametophytes in Arabidopsis Thaliana. Front Plant Sci 2011; 2:27. [PMID: 22639587 PMCID: PMC3355579 DOI: 10.3389/fpls.2011.00027] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Accepted: 06/21/2011] [Indexed: 05/13/2023]
Abstract
In angiosperms, mitosis and cytokinesis take place in the absence of structurally defined microtubule-organizing centers and the underlying mechanisms are largely unknown. In the spindle and phragmoplast, microtubule reorganization depends on microtubule-interacting factors like the γ-tubulin complex. Because of their critical functions in cell division, loss-of-function mutations in the corresponding genes are often homozygous or sporophytic lethal. However, a number of mutations like gem1, gcp2, and nedd1 can be maintained in heterozygous mutants in Arabidopsis thaliana. When mutant microspores produced by a heterozygous parent undergo pollen mitosis I, they are amenable for phenotypic characterization by fluorescence microscopy. The results would allow us to pinpoint at specific functions of particular proteins in microtubule reorganization that are characteristic to specific stages of mitosis and cytokinesis. Conclusions made in the developing microgametophytes can be extrapolated to somatic cells regarding mechanisms that regulate nuclear migration, spindle pole formation, phragmoplast assembly, and cell division plane determination.
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Affiliation(s)
- Bo Liu
- Department of Plant Biology, University of CaliforniaDavis, CA, USA
- *Correspondence: Bo Liu, Department of Plant Biology, University of California, 1 Shields Avenue, Davis, CA 95616, USA. e-mail:
| | | | - Yuh-Ru Julie Lee
- Department of Plant Biology, University of CaliforniaDavis, CA, USA
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23
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Kong Z, Hotta T, Lee YRJ, Horio T, Liu B. The {gamma}-tubulin complex protein GCP4 is required for organizing functional microtubule arrays in Arabidopsis thaliana. Plant Cell 2010; 22:191-204. [PMID: 20118227 PMCID: PMC2828712 DOI: 10.1105/tpc.109.071191] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2009] [Revised: 12/19/2009] [Accepted: 01/13/2010] [Indexed: 05/18/2023]
Abstract
Microtubule (MT) nucleation and organization depend on the evolutionarily conserved protein gamma -tubulin, which forms a complex with GCP2-GCP6 (GCP for gamma -Tubulin Complex Protein). To date, it is still unclear how GCP4-GCP6 (the non-core GCPs) may be involved in acentrosomal MT nucleation in plant cells. We found that GCP4 was associated with gamma -tubulin in vivo in Arabidopsis thaliana. When GCP4 expression was repressed by an artificial microRNA, transgenic plants exhibited phenotypes of dwarfism and reduced organ size. In mitotic cells, it was observed that the gamma -tubulin signal associated with the mitotic spindle, and the phragmoplast was depleted when GCP4 was downregulated. Consequently, MTs failed to converge at unified spindle poles, and the bipolar phragmoplast MT array frequently had discrete bundles with extended minus ends, resulting in failed cytokinesis as reflected by cell wall stubs in leaf epidermal cells. In addition, cortical MTs in swollen guard cells and pavement cells of the leaf epidermis became hyperparallel and bundled, which was likely caused by frequent MT nucleation with shallow angles on the wall of extant MTs. Therefore, our results support the notion that GCP4 is an indispensable component for the function of gamma -tubulin in MT nucleation and organization in plant cells.
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Affiliation(s)
- Zhaosheng Kong
- Department of Plant Biology, University of California, Davis, California 95616
| | - Takashi Hotta
- Department of Plant Biology, University of California, Davis, California 95616
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, University of California, Davis, California 95616
| | - Tetsuya Horio
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas 66045
| | - Bo Liu
- Department of Plant Biology, University of California, Davis, California 95616
- Address correspondence to
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24
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Guo L, Ho CMK, Kong Z, Lee YRJ, Qian Q, Liu B. Evaluating the microtubule cytoskeleton and its interacting proteins in monocots by mining the rice genome. Ann Bot 2009; 103:387-402. [PMID: 19106179 PMCID: PMC2707338 DOI: 10.1093/aob/mcn248] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 10/20/2008] [Accepted: 11/17/2008] [Indexed: 05/20/2023]
Abstract
BACKGROUND Microtubules (MTs) are assembled by heterodimers of alpha- and beta-tubulins, which provide tracks for directional transport and frameworks for the spindle apparatus and the phragmoplast. MT nucleation and dynamics are regulated by components such as the gamma-tubulin complex which are conserved among eukaryotes, and other components which are unique to plants. Following remarkable progress made in the model plant Arabidopsis thaliana toward revealing key components regulating MT activities, the completed rice (Oryza sativa) genome has prompted a survey of the MT cytoskeleton in this important crop as a model for monocots. SCOPE The rice genome contains three alpha-tubulin genes, eight beta-tubulin genes and a single gamma-tubulin gene. A functional gamma-tubulin ring complex is expected to form in rice as genes encoding all components of the complex are present. Among proteins that interact with MTs, compared with A. thaliana, rice has more genes encoding some members such as the MAP65/Ase1p/PRC1 family, but fewer for the motor kinesins, the end-binding protein EB1 and the mitotic kinase Aurora. Although most known MT-interacting factors have apparent orthologues in rice, no orthologues of arabidopsis RIC1 and MAP18 have been identified in rice. Among all proteins surveyed here, only a few have had their functions characterized by genetic means in rice. Elucidating functions of proteins of the rice MT cytoskeleton, aided by recent technical advances made in this model monocot, will greatly advance our knowledge of how monocots employ their MTs to regulate their growth and form.
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Affiliation(s)
- Longbiao Guo
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Chin-Min Kimmy Ho
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Zhaosheng Kong
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Yuh-Ru Julie Lee
- Department of Plant Biology, University of California, Davis, CA 95616, USA
| | - Qian Qian
- State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China
| | - Bo Liu
- Department of Plant Biology, University of California, Davis, CA 95616, USA
- For correspondence. E-mail:
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25
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Bisgrove SR, Lee YRJ, Liu B, Peters NT, Kropf DL. The microtubule plus-end binding protein EB1 functions in root responses to touch and gravity signals in Arabidopsis. Plant Cell 2008; 20:396-410. [PMID: 18281505 PMCID: PMC2276450 DOI: 10.1105/tpc.107.056846] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2007] [Revised: 01/20/2008] [Accepted: 01/31/2008] [Indexed: 05/19/2023]
Abstract
Microtubules function in concert with associated proteins that modify microtubule behavior and/or transmit signals that effect changes in growth. To better understand how microtubules and their associated proteins influence growth, we analyzed one family of microtubule-associated proteins, the END BINDING1 (EB1) proteins, in Arabidopsis thaliana (EB1a, EB1b, and EB1c). We find that antibodies directed against EB1 proteins colocalize with microtubules in roots, an observation that confirms previous reports using EB1-GFP fusions. We also find that T-DNA insertion mutants with reduced expression from EB1 genes have roots that deviate toward the left on vertical or inclined plates. Mutant roots also exhibit extended horizontal growth before they bend downward after tracking around an obstacle or after a 90 degrees clockwise reorientation of the root. These observations suggest that leftward deviations in root growth may be the result of delayed responses to touch and/or gravity signals. Root lengths and widths are normal, indicating that the delay in bend formation is not due to changes in the overall rate of growth. In addition, the genotype with the most severe defects responds to low doses of microtubule inhibitors in a manner indistinguishable from the wild type, indicating that microtubule integrity is not a major contributor to the leftward deviations in mutant root growth.
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Affiliation(s)
- Sherryl R Bisgrove
- Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6.
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26
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Lee YRJ, Li Y, Liu B. Two Arabidopsis phragmoplast-associated kinesins play a critical role in cytokinesis during male gametogenesis. Plant Cell 2007; 19:2595-605. [PMID: 17720869 PMCID: PMC2002617 DOI: 10.1105/tpc.107.050716] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
In plant cells, cytokinesis is brought about by the phragmoplast. The phragmoplast has a dynamic microtubule array of two mirrored sets of microtubules, which are aligned perpendicularly to the division plane with their plus ends located at the division site. It is not well understood how the phragmoplast microtubule array is organized. In Arabidopsis thaliana, two homologous microtubule motor kinesins, PAKRP1/Kinesin-12A and PAKRP1L/Kinesin-12B, localize exclusively at the juxtaposing plus ends of the antiparallel microtubules in the middle region of the phragmoplast. When either kinesin was knocked out by T-DNA insertions, mutant plants did not show a noticeable defect. However, in the absence of both kinesins, postmeiotic development of the male gametophyte was severely inhibited. In dividing microspores of the double mutant, microtubules often became disorganized following chromatid segregation and failed to form an antiparallel microtubule array between reforming nuclei. Consequently, the first postmeiotic cytokinesis was abolished without the formation of a cell plate, which led to failures in the birth of the generative cell and, subsequently, the sperm. Thus, our results indicate that Kinesin-12A and Kinesin-12B jointly play a critical role in the organization of phragmoplast microtubules during cytokinesis in the microspore that is essential for cell plate formation. Furthermore, we conclude that Kinesin-12 members serve as dynamic linkers of the plus ends of antiparallel microtubules in the phragmoplast.
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Affiliation(s)
- Yuh-Ru Julie Lee
- Section of Plant Biology, University of California, Davis, California 95616, USA
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Lu L, Lee YRJ, Pan R, Maloof JN, Liu B. An internal motor kinesin is associated with the Golgi apparatus and plays a role in trichome morphogenesis in Arabidopsis. Mol Biol Cell 2004; 16:811-23. [PMID: 15574882 PMCID: PMC545913 DOI: 10.1091/mbc.e04-05-0400] [Citation(s) in RCA: 114] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Members of the kinesin superfamily are microtubule-based motor proteins that transport molecules/organelles along microtubules. We have identified similar internal motor kinesins, Kinesin-13A, from the cotton Gossypium hirsutum and Arabidopsis thaliana. Their motor domains share high degree of similarity with those of internal motor kinesins of animals and protists in the MCAK/Kinesin13 subfamily. However, no significant sequence similarities were detected in sequences outside the motor domain. In Arabidopsis plants carrying the T-DNA knockout kinesin-13a-1 and kinesin-13a-2 mutations at the Kinesin-13A locus, >70% leaf trichomes had four branches, whereas wild-type trichomes had three. Immunofluorescent results showed that AtKinesin-13A and GhKinesin-13A localized to entire Golgi stacks. In both wild-type and kinesin-13a mutant cells, the Golgi stacks were frequently associated with microtubules and with actin microfilaments. Aggregation/clustering of Golgi stacks was often observed in the kinesin-13a mutant trichomes and other epidermal cells. This suggested that the distribution of the Golgi apparatus in cell cortex might require microtubules and Kinesin-13A, and the organization of Golgi stacks could play a regulatory role in trichome morphogenesis. Our results also indicate that plant kinesins in the MCAK/Kinesin-13 subfamily have evolved to take on different tasks than their animal counterparts.
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Affiliation(s)
- Ling Lu
- Section of Plant Biology, University of California, Davis, Davis, CA 95616, USA
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Lee YRJ, Liu B. Cytoskeletal motors in Arabidopsis. Sixty-one kinesins and seventeen myosins. Plant Physiol 2004; 136:3877-83. [PMID: 15591445 PMCID: PMC535821 DOI: 10.1104/pp.104.052621] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2004] [Revised: 10/28/2004] [Accepted: 11/01/2004] [Indexed: 05/17/2023]
Affiliation(s)
- Yuh-Ru Julie Lee
- Section of Plant Biology, University of California, Davis, California 95616, USA
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Liu B, Xiang X, Lee YRJ. The requirement of the LC8 dynein light chain for nuclear migration and septum positioning is temperature dependent in Aspergillus nidulans. Mol Microbiol 2003; 47:291-301. [PMID: 12519184 DOI: 10.1046/j.1365-2958.2003.03285.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In the filamentous fungus Aspergillus nidulans, the multisubunit motor complex cytoplasmic dynein plays essential roles in nuclear migration and septum positioning. The 8 kDa light chain, LC8, the smallest subunit, is conserved among eukaryotic organisms. Besides being a component in the dynein complex, LC8 also interacts with a wide spectrum of mammalian and viral proteins. To date, the function of this small polypeptide is not well understood. To address this issue, we have created a deletion mutation (DeltanudG) at the nudG locus encoding LC8 in A. nidulans. At 42 degrees C, the DeltanudG mutant forms minute colonies lacking asexual reproduction: this phenotype resembles the phenotype of the dynein heavy chain null mutant. The mutant nuclei largely clustered in the spore body after conidial germination, and the septum was often assembled distally toward the hyphal apex, whereas a control germling has its nuclei distributed along the hypha and the septum formed near the spore body. When the mutant was grown at 23 degrees C, however, its colony resembled a control one, and so did the patterns of nuclear distribution and septum positioning. Elevation of the growth temperature gradually reduced colony size and abolished asexual sporulation. After a period of growth at 23 degrees C that allowed the nuclei to move out of the spore end, a temperature shift to 42 degrees C prevented newly divided nuclei from migrating apart, suggesting that LC8/NUDG was required for both initiating and maintaining dynein motor functions at elevated temperatures. A functional GFP-NUDA fusion was used to test whether LC8/NUDG is required for DHC (dynein heavy chain)/NUDA localization. We found that at 23 degrees C GFP-NUDA localized to the hyphal apex and the septation site in DeltanudG cells as in control cells. Such localizations were absent at 42 degrees C in mutant cells, but not in control cells. We conclude that LC8 plays a role in DHC localization/function, and the requirement for such a role in A. nidulans cells is temperature dependent.
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Affiliation(s)
- Bo Liu
- Section of Plant Biology, University of California, One Shields Avenue, Davis, CA 95616, USA.
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